NASA Astrophysics Data System (ADS)
Kulkanarni, Akshay Kishor
We present results of three-dimensional (3D) simulations of magnetohydrodynamic (MHD) instabilities at the accretion disk-magnetosphere boundary in accreting magnetized stars. The instability is Rayleigh-Taylor, and develops for a fairly broad range of accretion rates and stellar rotation rates and magnetic fields. It manifests itself in the form of tall, thin tongues of plasma that penetrate the magnetosphere in the equatorial plane, instead of flowing around the magnetosphere as in the canonical accretion picture. The shape and number of the tongues changes with time on the inner-disk dynamical timescale. In contrast with funnel flows, which deposit matter mainly in the polar region, the tongues deposit matter much closer to the stellar equator. The instability appears for relatively small misalignment angles, theta ≲ 30°, between the star's rotation and magnetic axes, and is associated with relatively high accretion rates. We then calculate the photometric variability due to emission from the hot spots that the accreting matter produces on the stellar surface. For neutron stars, we take relativistic effects into account in calculating the observed energy flux. Our goal is to compare the features of the lightcurve during stable and unstable accretion, and to look for possible quasi-periodic oscillations (QPOs), which produce broad peaks in the Fourier power spectra of these objects. The lightcurves during stable accretion show periodicity at the star's frequency and sometimes twice that, due to the presence of two funnel streams that produce antipodal hotspots near the magnetic poles. On the other hand, lightcurves during unstable accretion are more chaotic due to the stochastic behaviour of the tongues, and produce noisier power spectra. However, the power spectra do show some signs of quasi-periodic variability. Most importantly, the rotation frequency of the tongues and the resulting hotspots is close to the inner-disk orbital frequency, except in the most
Three-Dimensional DNA Nanostructures Assembled from DNA Star Motifs.
Tian, Cheng; Zhang, Chuan
2017-01-01
Tile-based DNA self-assembly is a promising method in DNA nanotechnology and has produced a wide range of nanostructures by using a small set of unique DNA strands. DNA star motif, as one of DNA tiles, has been employed to assemble varieties of symmetric one-, two-, three-dimensional (1, 2, 3D) DNA nanostructures. Herein, we describe the design principles, assembly methods, and characterization methods of 3D DNA nanostructures assembled from the DNA star motifs.
Star-triangle relation for a three-dimensional model
Bazhanov, V.V. Institute for High Eenrgy Physics, Protvino, Moscow Region ); Baxter, R.J. Australian National Univ., Canberra )
1993-06-01
The solvable sl(n)-chiral Potts model can be interpreted as a three-dimensional lattice model with local interactions. To within a minor modification of the boundary conditions it is an Ising-type model on the body-centered cubic lattice with two- and three-spin interactions. The corresponding local Boltzmann weights obey a number of simple relations, including a restricted star-triangle relation, which is a modified version of the well-known star-triangle relation appearing in two-dimensional models. It is shown that these relations lead to remarkable symmetry properties of the Boltzmann weight function of an elementary cube of the lattice, related to the spatial symmetry group of the cubic lattice. These symmetry properties allow one to prove the commutativity of the row-to-row transfer matrices, bypassing the tetrahedron relation. The partition function per site for the infinite lattice is calculated exactly. 20 refs., 4 figs.
Three dimensional global modeling of atmospheric CO2
NASA Technical Reports Server (NTRS)
Fung, I.; Hansen, J.; Rind, D.
1983-01-01
A model was developed to study the prospects of extracting information on carbon dioxide sources and sinks from observed CO2 variations. The approach uses a three dimensional global transport model, based on winds from a 3-D general circulation model (GCM), to advect CO2 noninteractively, i.e., as a tracer, with specified sources and sinks of CO2 at the surface. The 3-D model employed is identified and biosphere, ocean and fossil fuel sources and sinks are discussed. Some preliminary model results are presented.
Pliocene three-dimensional global ocean temperature reconstruction
Dowsett, H.J.; Robinson, M.M.; Foley, K.M.
2009-01-01
A snapshot of the thermal structure of the mid-Piacenzian ocean is obtained by combining the Pliocene Research, Interpretation and Synoptic Mapping Project (PRISM3) multiproxy sea-surface temperature (SST) reconstruction with bottom water tempera-5 ture estimates produced using Mg/Ca paleothermometry. This reconstruction assumes a Pliocene water mass framework similar to that which exists today, with several important modifications. The area of formation of present day North Atlantic Deep Water (NADW) was expanded and extended further north toward the Arctic Ocean during the mid-Piacenzian relative to today. This, combined with a deeper Greenland-Scotland Ridge, allowed a greater volume of warmer NADW to enter the Atlantic Ocean. In the Southern Ocean, the Polar Front Zone was expanded relative to present day, but shifted closer to the Antarctic continent. This, combined with at least seasonal reduction in sea ice extent, resulted in decreased Antarctic BottomWater (AABW) production (relative to present day) as well as possible changes in the depth of intermediate wa15 ters. The reconstructed mid-Piacenzian three-dimensional ocean was warmer overall than today, and the hypothesized aerial extent of water masses appears to fit the limited stable isotopic data available for this time period. ?? Author(s) 2009.
Pliocene three-dimensional global ocean temperature reconstruction
Dowsett, H.J.; Robinson, M.M.; Foley, K.M.
2009-01-01
The thermal structure of the mid-Piacenzian ocean is obtained by combining the Pliocene Research, Interpretation and Synoptic Mapping Project (PRISM3) multiproxy sea-surface temperature (SST) reconstruction with bottom water temperature estimates from 27 locations produced using Mg/Ca paleothermometry based upon the ostracod genus Krithe. Deep water temperature estimates are skewed toward the Atlantic Basin (63% of the locations) and represent depths from 1000m to 4500 m. This reconstruction, meant to serve as a validation data set as well as an initialization for coupled numerical climate models, assumes a Pliocene water mass framework similar to that which exists today, with several important modifications. The area of formation of present day North Atlantic Deep Water (NADW) was expanded and extended further north toward the Arctic Ocean during the mid-Piacenzian relative to today. This, combined with a deeper Greenland-Scotland Ridge, allowed a greater volume of warmer NADW to enter the Atlantic Ocean. In the Southern Ocean, the Polar Front Zone was expanded relative to present day, but shifted closer to the Antarctic continent. This, combined with at least seasonal reduction in sea ice extent, resulted in decreased Antarctic Bottom Water (AABW) production (relative to present day) as well as possible changes in the depth of intermediate waters. The reconstructed mid-Piacenzian three-dimensional ocean was warmer overall than today, and the hypothesized aerial extent of water masses appears to fit the limited stable isotopic data available for this time period. ?? Author(s) 2009.
A THREE-DIMENSIONAL MODEL ASSESSMENT OF THE GLOBAL DISTRIBUTION OF HEXACHLOROBENZENE
The distributions of persistent organic pollutants (POPs) in the global environment have been studied typically with box/fugacity models with simplified treatments of atmospheric transport processes1. Such models are incapable of simulating the complex three-dimensional mechanis...
Three dimensional global modeling of atmospheric CO2
NASA Technical Reports Server (NTRS)
Hanse, J.; Fung, I.; Rind, D.
1984-01-01
The initial attempts to model the atmospheric CO2 distribution, including couplings to the ocean and biosphere as sources and sinks of atmospheric CO2, encourage the notion that this approach will lead to useful quantitative constraints on CO2 fluxes. Realization of this objective will require: (1) continued improvement in the realism of the global transport modeling; (2) extended timeline of atmospheric CO2 monitoring, which improved precision and improved definition of the uncertainties in the measured CO2 amounts; and (3) given an accurate knowledge of model capabilities and limitations and given a good understanding of CO2 observations and their limitations, there is a need for good ideas concerning what quantitative information on the carbon cycle can be inferred from global modeling.
The Stellar Cusp in the Galactic Center: Three-Dimensional Orbits of Stars
NASA Astrophysics Data System (ADS)
Chappell, Samantha; Ghez, Andrea M.; Boehle, Anna; Yelda, Sylvana; Sitarski, Breann; Witzel, Gunther; Do, Tuan; Lu, Jessica R.; Morris, Mark; Becklin, Eric E.
2015-01-01
We present new findings from our long term study of the nuclear star cluster around the Galaxy's central supermassive blackhole (SMBH). Measurements where made using speckle and laser guided adaptive optics imaging and integral field spectroscopy on the Keck telescopes. We report 13 new measurable accelerating sources around the SMBH, down to ~17 mag in K band, only 4 of which are known to be young stars, the rest are either known to be old stars or have yet to be spectral typed. Thus we more than double the number of measured accelerations for the known old stars and unknown spectral type population (increasing the number from 6 to 15). Previous observations suggest a flat density profile of late-type stars, contrary to the theorized Bahcall-Wolf cusp (Bahcall & Wolf 1976, 1977; Buchholz et al. 2009; Do et al. 2009; Bartko et al. 2010). With three-dimensional orbits of significantly accelerating sources, we will be able to better characterize the stellar cusp in the Galactic center, including the slope of the stellar density profile.
NASA Astrophysics Data System (ADS)
Xu, Li; Zhang, Ping; Zhang, Zhifei
2013-06-01
Motivated by Beale (Commun Pure Appl Math 34:359-392, 1981; Arch Ration Mech Anal 84:307-352, 1983/1984), we investigate the global well-posedness of a free boundary problem of a three-dimensional incompressible viscoelastic fluid system in an infinite strip and with surface tension on the upper free boundary, provided that the initial data is sufficiently close to the equilibrium state.
THE THREE-DIMENSIONAL EVOLUTION TO CORE COLLAPSE OF A MASSIVE STAR
Couch, Sean M.; Chatzopoulos, Emmanouil; Arnett, W. David; Timmes, F. X.
2015-07-20
We present the first three-dimensional (3D) simulation of the final minutes of iron core growth in a massive star, up to and including the point of core gravitational instability and collapse. We capture the development of strong convection driven by violent Si burning in the shell surrounding the iron core. This convective burning builds the iron core to its critical mass and collapse ensues, driven by electron capture and photodisintegration. The non-spherical structure and motion generated by 3D convection is substantial at the point of collapse, with convective speeds of several hundreds of km s{sup −1}. We examine the impact of such physically realistic 3D initial conditions on the core-collapse supernova mechanism using 3D simulations including multispecies neutrino leakage and find that the enhanced post-shock turbulence resulting from 3D progenitor structure aids successful explosions. We conclude that non-spherical progenitor structure should not be ignored, and should have a significant and favorable impact on the likelihood for neutrino-driven explosions. In order to make simulating the 3D collapse of an iron core feasible, we were forced to make approximations to the nuclear network making this effort only a first step toward accurate, self-consistent 3D stellar evolution models of the end states of massive stars.
1985-04-23
8217 geodetic networks; three, dimensional geodesy, satellite geodesy, NAVSTAR Global Positioning System,’ GPS , interferometry 20. ABSTRACT (Continue on reverse...8217 - - .. . . . . . . . . . . . . . -t INTRODUCTION GPS interferometry is a method by which three-dimensional relative-position vectors between observing stations can be
Neutron Star Population Dynamics. II. Three-dimensional Space Velocities of Young Pulsars
NASA Astrophysics Data System (ADS)
Cordes, J. M.; Chernoff, David F.
1998-09-01
We use astrometric, distance, and spindown data on pulsars to (1) estimate three-dimensional velocity components, birth distances from the Galactic plane, and ages of individual objects; (2) determine the distribution of space velocities and the scale height of pulsar progenitors; (3) test spindown laws for pulsars; (4) test for correlations between space velocities and other pulsar parameters; and (5) place empirical requirements on mechanisms than can produce high-velocity neutron stars. Our approach incorporates measurement errors, uncertainties in distances, deceleration in the Galactic potential, and differential Galactic rotation. We focus on a sample of proper motion measurements of young (<10 Myr) pulsars whose trajectories may be accurately and simply modeled. This sample of 49 pulsars excludes millisecond pulsars and other objects that may have undergone accretion-driven spinup. We estimate velocity components and birth z distance on a case-by-case basis assuming that the actual age equals the conventional spindown age for a braking index n = 3, no torque decay, and birth periods much shorter than present-day periods. Every sample member could have originated within 0.3 kpc of the Galactic plane while still having reasonable present-day peculiar radial velocities. For the 49 object sample, the scale height of the progenitors is ~0.13 kpc, and the three-dimensional velocities are distributed in two components with characteristic speeds of 175+19-24 km s-1 and 700+300-132 km s-1, representing ~86% and ~14% of the population, respectively. The sample velocities are inconsistent with a single-component Gaussian model and are well described by a two-component Gaussian model but do not require models of additional complexity. From the best-fit distribution, we estimate that about 20% of the known pulsars will escape the Galaxy, assuming an escape speed of 500 km s-1. The best-fit, dual-component model, if augmented by an additional, low-velocity (<50 km s-1
NASA Astrophysics Data System (ADS)
Chen, Hui; Fang, Daoyuan; Zhang, Ting
2017-02-01
In this paper, we investigate the global well-posedness for the three dimensional inhomogeneous incompressible Navier-Stokes system with axisymmetric initial data. We obtain the global existence and uniqueness of the axisymmetric solution provided that |a0/r|_{∞} and |u0^{θ}|3 {are sufficiently small}. Furthermore, if {u_0 in L1} and {ru^{θ}0in L1 \\cap L2} , we have the decay estimate |u^{θ}(t)|22 + < t rangle |nabla(u^{θ}e_{θ})(t)|22 + t< t rangle(|ut^{θ}(t)|22 + |Δ(u^{θ}e_{θ})(t)|22) ≤q C < trangle^{-5/2}, quad forall t > 0.
NASA Astrophysics Data System (ADS)
Lihoreau, Mathieu; Ings, Thomas C.; Chittka, Lars; Reynolds, Andy M.
2016-07-01
Simulated annealing is a powerful stochastic search algorithm for locating a global maximum that is hidden among many poorer local maxima in a search space. It is frequently implemented in computers working on complex optimization problems but until now has not been directly observed in nature as a searching strategy adopted by foraging animals. We analysed high-speed video recordings of the three-dimensional searching flights of bumblebees (Bombus terrestris) made in the presence of large or small artificial flowers within a 0.5 m3 enclosed arena. Analyses of the three-dimensional flight patterns in both conditions reveal signatures of simulated annealing searches. After leaving a flower, bees tend to scan back-and forth past that flower before making prospecting flights (loops), whose length increases over time. The search pattern becomes gradually more expansive and culminates when another rewarding flower is found. Bees then scan back and forth in the vicinity of the newly discovered flower and the process repeats. This looping search pattern, in which flight step lengths are typically power-law distributed, provides a relatively simple yet highly efficient strategy for pollinators such as bees to find best quality resources in complex environments made of multiple ephemeral feeding sites with nutritionally variable rewards.
A three-dimensional high Mach number asymmetric magnetopause model from global MHD simulation
NASA Astrophysics Data System (ADS)
Liu, Z.-Q.; Lu, J. Y.; Wang, C.; Kabin, K.; Zhao, J. S.; Wang, M.; Han, J. P.; Wang, J. Y.; Zhao, M. X.
2015-07-01
The numerical results from a physics-based global magnetohydrodynamic (MHD) model are used to examine the effect of the interplanetary magnetic field (IMF), solar wind dynamic pressure, and dipole tilt angle on the size and shape of the magnetopause. The subsolar magnetopause is identified using the plasma velocity and density, the cusps are identified using the thermal pressure, and the whole shape of the magnetopause is determined with the three-dimensional streamlines traced through the simulation domain. The magnetopause surface obtained from the simulations is fitted with a three-dimensional surface function controlled by ten configuration parameters, which provide a description of the subsolar magnetopause, the cusp geometry, the flaring angle, the azimuthal asymmetry, the north-south asymmetry, and the twisting angle of the magnetopause. Effects of the IMF, solar wind dynamic pressure, and dipole tilt angle on the configuration parameters are analyzed and fitted by relatively simple functions. It is found that the solar wind dynamic pressure mainly affects the magnetopause size; the IMF mainly controls the magnetopause flaring angle, azimuthal asymmetry, and twisting angle; and the dipole tilt angle mainly affects the magnetopause north-south asymmetry and the cusp geometry. The model is validated by comparing with available empirical models and observational results, and it is demonstrated that the new model can describe the magnetopause for typical solar wind conditions.
Lihoreau, Mathieu; Ings, Thomas C; Chittka, Lars; Reynolds, Andy M
2016-07-27
Simulated annealing is a powerful stochastic search algorithm for locating a global maximum that is hidden among many poorer local maxima in a search space. It is frequently implemented in computers working on complex optimization problems but until now has not been directly observed in nature as a searching strategy adopted by foraging animals. We analysed high-speed video recordings of the three-dimensional searching flights of bumblebees (Bombus terrestris) made in the presence of large or small artificial flowers within a 0.5 m(3) enclosed arena. Analyses of the three-dimensional flight patterns in both conditions reveal signatures of simulated annealing searches. After leaving a flower, bees tend to scan back-and forth past that flower before making prospecting flights (loops), whose length increases over time. The search pattern becomes gradually more expansive and culminates when another rewarding flower is found. Bees then scan back and forth in the vicinity of the newly discovered flower and the process repeats. This looping search pattern, in which flight step lengths are typically power-law distributed, provides a relatively simple yet highly efficient strategy for pollinators such as bees to find best quality resources in complex environments made of multiple ephemeral feeding sites with nutritionally variable rewards.
Lihoreau, Mathieu; Ings, Thomas C.; Chittka, Lars; Reynolds, Andy M.
2016-01-01
Simulated annealing is a powerful stochastic search algorithm for locating a global maximum that is hidden among many poorer local maxima in a search space. It is frequently implemented in computers working on complex optimization problems but until now has not been directly observed in nature as a searching strategy adopted by foraging animals. We analysed high-speed video recordings of the three-dimensional searching flights of bumblebees (Bombus terrestris) made in the presence of large or small artificial flowers within a 0.5 m3 enclosed arena. Analyses of the three-dimensional flight patterns in both conditions reveal signatures of simulated annealing searches. After leaving a flower, bees tend to scan back-and forth past that flower before making prospecting flights (loops), whose length increases over time. The search pattern becomes gradually more expansive and culminates when another rewarding flower is found. Bees then scan back and forth in the vicinity of the newly discovered flower and the process repeats. This looping search pattern, in which flight step lengths are typically power-law distributed, provides a relatively simple yet highly efficient strategy for pollinators such as bees to find best quality resources in complex environments made of multiple ephemeral feeding sites with nutritionally variable rewards. PMID:27459948
Slab1.0: A three-dimensional model of global subduction zone geometries
Hayes, G.P.; Wald, D.J.; Johnson, R.L.
2012-01-01
We describe and present a new model of global subduction zone geometries, called Slab1.0. An extension of previous efforts to constrain the two-dimensional non-planar geometry of subduction zones around the focus of large earthquakes, Slab1.0 describes the detailed, non-planar, three-dimensional geometry of approximately 85% of subduction zones worldwide. While the model focuses on the detailed form of each slab from their trenches through the seismogenic zone, where it combines data sets from active source and passive seismology, it also continues to the limits of their seismic extent in the upper-mid mantle, providing a uniform approach to the definition of the entire seismically active slab geometry. Examples are shown for two well-constrained global locations; models for many other regions are available and can be freely downloaded in several formats from our new Slab1.0 website, http://on.doi.gov/ d9ARbS. We describe improvements in our two-dimensional geometry constraint inversion, including the use of average active source seismic data profiles in the shallow trench regions where data are otherwise lacking, derived from the interpolation between other active source seismic data along-strike in the same subduction zone. We include several analyses of the uncertainty and robustness of our three-dimensional interpolation methods. In addition, we use the filtered, subduction-related earthquake data sets compiled to build Slab1.0 in a reassessment of previous analyses of the deep limit of the thrust interface seismogenic zone for all subduction zones included in our global model thus far, concluding that the width of these seismogenic zones is on average 30% larger than previous studies have suggested. Copyright 2011 by the American Geophysical Union.
Global climate changes as forecast by Goddard Institute for Space Studies three-dimensional model
NASA Technical Reports Server (NTRS)
Hansen, J.; Fung, I.; Lacis, A.; Rind, D.; Lebedeff, S.; Ruedy, R.; Russell, G.
1988-01-01
The global climate effects of time-dependent atmospheric trace gas and aerosol variations are simulated by NASA-Goddard's three-dimensional climate model II, which possesses 8 x 10-deg horizontal resolution, for the cases of a 100-year control run and three different atmospheric composition scenarios in which trace gas growth is respectively a continuation of current exponential trends, a reduced linear growth, and a rapid curtailment of emissions due to which net climate forcing no longer increases after the year 2000. The experiments begin in 1958, run to the present, and encompass measured or estimated changes in CO2, CH4, N2O, chlorofluorocarbons, and stratospheric aerosols. It is shown that the greenhouse warming effect may be clearly identifiable in the 1990s.
NASA Astrophysics Data System (ADS)
Rastigejev, Y.; Semakin, A. N.
2013-12-01
Accurate numerical simulations of global scale three-dimensional atmospheric chemical transport models (CTMs) are essential for studies of many important atmospheric chemistry problems such as adverse effect of air pollutants on human health, ecosystems and the Earth's climate. These simulations usually require large CPU time due to numerical difficulties associated with a wide range of spatial and temporal scales, nonlinearity and large number of reacting species. In our previous work we have shown that in order to achieve adequate convergence rate and accuracy, the mesh spacing in numerical simulation of global synoptic-scale pollution plume transport must be decreased to a few kilometers. This resolution is difficult to achieve for global CTMs on uniform or quasi-uniform grids. To address the described above difficulty we developed a three-dimensional Wavelet-based Adaptive Mesh Refinement (WAMR) algorithm. The method employs a highly non-uniform adaptive grid with fine resolution over the areas of interest without requiring small grid-spacing throughout the entire domain. The method uses multi-grid iterative solver that naturally takes advantage of a multilevel structure of the adaptive grid. In order to represent the multilevel adaptive grid efficiently, a dynamic data structure based on indirect memory addressing has been developed. The data structure allows rapid access to individual points, fast inter-grid operations and re-gridding. The WAMR method has been implemented on parallel computer architectures. The parallel algorithm is based on run-time partitioning and load-balancing scheme for the adaptive grid. The partitioning scheme maintains locality to reduce communications between computing nodes. The parallel scheme was found to be cost-effective. Specifically we obtained an order of magnitude increase in computational speed for numerical simulations performed on a twelve-core single processor workstation. We have applied the WAMR method for numerical
Three-Dimensional Nuclear Chart--Understanding Nuclear Physics and Nucleosynthesis in Stars
ERIC Educational Resources Information Center
Koura, Hiroyuki
2014-01-01
Three-dimensional (3D) nuclear charts were created using toy blocks, which represent the atomic masses per nucleon number and the total half-lives for each nucleus in the entire region of the nuclear mass. The bulk properties of the nuclei can be easily understood by using these charts. Subsequently, these charts were used in outreach activities…
Evolution of flux ropes in the magnetotail: A three-dimensional global hybrid simulation
Lu, S.; Lin, Y.; Wang, X. Y.; Lu, Q. M. Huang, C.; Wu, M. Y.; Wang, S.; Wang, R. S.
2015-05-15
Flux ropes in the Earth's magnetotail are widely believed to play a crucial role in energy transport during substorms and the generation of energetic particles. Previous kinetic simulations are limited to the local-scale regime, and thus cannot be used to study the structure associated with the geomagnetic field and the global-scale evolution of the flux ropes. Here, the evolution of flux ropes in the magnetotail under a steady southward interplanetary magnetic field are studied with a newly developed three-dimensional global hybrid simulation model for dynamics ranging from the ion Larmor radius to the global convection time scales. Magnetic reconnection with multiple X-lines is found to take place in the near-tail current sheet at geocentric solar magnetospheric distances x=−30R{sub E}∼−15R{sub E} around the equatorial plane (z=0). The magnetotail reconnection layer is turbulent, with a nonuniform structure and unsteady evolution, and exhibits properties of typical collisionless fast reconnection with the Hall effect. A number of small-scale flux ropes are generated through the multiple X-line reconnection. The diameter of the flux ropes is several R{sub E}, and the spatial scale of the flux ropes in the dawn-dusk direction is on the order of several R{sub E} and does not extend across the entire section of the magnetotail, contrary to previous models and MHD simulation results and showing the importance of the three-dimensional effects. The nonuniform and unsteady multiple X-line reconnection with particle kinetic effects leads to various kinds of flux rope evolution: The small-scale flux ropes propagate earthward or tailward after formation, and eventually merge into the near-Earth region or the mid-/distant-tail plasmoid, respectively. During the propagation, some of the flux ropes can be tilted in the geocentric solar magnetospheric (x,y) plane with respect to the y (dawn-dusk) axis. Coalescence between flux ropes is also observed. At the same time, the
GLOBAL NON-SPHERICAL OSCILLATIONS IN THREE-DIMENSIONAL 4π SIMULATIONS OF THE H-INGESTION FLASH
Herwig, Falk; Woodward, Paul R.; Lin, Pei-Hung; Knox, Mike; Fryer, Chris
2014-09-01
We performed three-dimensional simulations of proton-rich material entrainment into {sup 12}C-rich He-shell flash convection and the subsequent H-ingestion flash that took place in the post-asymptotic giant branch star Sakurai's object. Observations of the transient nature and anomalous abundance features are available to validate our method and assumptions, with the aim of applying them to very low-metallicity stars in the future. We include nuclear energy feedback from H burning and cover the full 4π geometry of the shell. Runs on 768{sup 3} and 1536{sup 3} grids agree well with each other and have been followed for 1500 minutes and 1200 minutes. After an 850 minute long quiescent entrainment phase, the simulations enter into a global non-spherical oscillation that is launched and sustained by individual ignition events of H-rich fluid pockets. Fast circumferential flows collide at the antipode and cause the formation and localized ignition of the next H-overabundant pocket. The cycle repeats for more than a dozen times while its amplitude decreases. During the global oscillation, the entrainment rate increases temporarily by a factor of ≈100. Entrained entropy quenches convective motions in the upper layer until the burning of entrained H establishes a separate convection zone. The lower-resolution run hints at the possibility that another global oscillation, perhaps even more violent, will follow. The location of the H-burning convection zone agrees with a one-dimensional model in which the mixing efficiency is calibrated to reproduce the light curve. The simulations have been performed at the NSF Blue Waters supercomputer at NCSA.
Global three-dimensional simulation and radiative forcing of various aerosol species with GCM
NASA Astrophysics Data System (ADS)
Takemura, Toshihiko; Okamoto, Hajime; Numaguti, Atusi; Suzuki, Kentaroh; Higurashi, Akiko; Nakajima, Teruyuki
2001-02-01
A global three-dimensional transport model that can simultaneously treat main tropospheric aerosols, i.e., carbonaceous (organic and black carbons), sulfate, soil dust, and sea salt, is developed. It is coupled with a Center for Climate System Research (CCSR)/National Institute for Enviormental Studies (NIES) atmospheric general circulation model (AGCM), and the meteorological field of wind, temperature, and specific humidity can be nudged by reanalysis data. Simulated results are compared with not only observations for aerosol concentrations but also the optical thickness and Angstrom exponent retrieved from remote sensing data such as National Oceanic and Atmospheric Administration (NOAA)/Advanced Very High Resolution Radiometer (AVHRR) and Aerosol Robotic Network (AERONET). A general agreement is found between simulated results and observations spatially seasonally, and quantitatively. The present model is also coupled with the radiative process over both the solar and thermal regions. The annual and global mean radiative forcing by anthropogenic aerosols from fossil fuel sources is estimated to be -0.5 W m-2 over the clear sky for the direct effect and -2.0 W m-2 for the indirect effect.
NASA Technical Reports Server (NTRS)
Liu, Hongyu; Crawford, James H.; Pierce, Robert B.; Norris, Peter; Platnick, Steven E.; Chen, Gao; Logan, Jennifer A.; Yantosca, Robert M.; Evans, Mat J.; Kittaka, Chieko; Feng, Yan; Tie, Xuexi
2006-01-01
Clouds exert an important influence on tropospheric photochemistry through modification of solar radiation that determines photolysis frequencies (J-values). We assess the radiative effect of clouds on photolysis frequencies and key oxidants in the troposphere with a global three-dimensional (3-D) chemical transport model (GEOS-CHEM) driven by assimilated meteorological observations from the Goddard Earth Observing System data assimilation system (GEOS DAS) at the NASA Global Modeling and Assimilation Office (GMAO). We focus on the year of 2001 with the GEOS-3 meteorological observations. Photolysis frequencies are calculated using the Fast-J radiative transfer algorithm. The GEOS-3 global cloud optical depth and cloud fraction are evaluated and generally consistent with the satellite retrieval products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the International Satellite Cloud Climatology Project (ISCCP). Results using the linear assumption, which assumes linear scaling of cloud optical depth with cloud fraction in a grid box, show global mean OH concentrations generally increase by less than 6% because of the radiative effect of clouds. The OH distribution shows much larger changes (with maximum decrease of approx.20% near the surface), reflecting the opposite effects of enhanced (weakened) photochemistry above (below) clouds. The global mean photolysis frequencies for J[O1D] and J[NO2] in the troposphere change by less than 5% because of clouds; global mean O3 concentrations in the troposphere increase by less than 5%. This study shows tropical upper tropospheric O3 to be less sensitive to the radiative effect of clouds than previously reported (approx.5% versus approx.20-30%). These results emphasize that the dominant effect of clouds is to influence the vertical redistribution of the intensity of photochemical activity while global average effects remain modest, again contrasting with previous studies. Differing vertical distributions
NASA Astrophysics Data System (ADS)
Ngwira, Chigomezyo M.; Pulkkinen, Antti; Kuznetsova, Maria M.; Glocer, Alex
2014-06-01
There is a growing concern over possible severe societal consequences related to adverse space weather impacts on man-made technological infrastructure. In the last two decades, significant progress has been made toward the first-principles modeling of space weather events, and three-dimensional (3-D) global magnetohydrodynamics (MHD) models have been at the forefront of this transition, thereby playing a critical role in advancing our understanding of space weather. However, the modeling of extreme space weather events is still a major challenge even for the modern global MHD models. In this study, we introduce a specially adapted University of Michigan 3-D global MHD model for simulating extreme space weather events with a Dst footprint comparable to the Carrington superstorm of September 1859 based on the estimate by Tsurutani et. al. (2003). Results are presented for a simulation run with "very extreme" constructed/idealized solar wind boundary conditions driving the magnetosphere. In particular, we describe the reaction of the magnetosphere-ionosphere system and the associated induced geoelectric field on the ground to such extreme driving conditions. The model setup is further tested using input data for an observed space weather event of Halloween storm October 2003 to verify the MHD model consistence and to draw additional guidance for future work. This extreme space weather MHD model setup is designed specifically for practical application to the modeling of extreme geomagnetically induced electric fields, which can drive large currents in ground-based conductor systems such as power transmission grids. Therefore, our ultimate goal is to explore the level of geoelectric fields that can be induced from an assumed storm of the reported magnitude, i.e., Dst˜=-1600 nT.
Upper ocean ecosystem dynamics and iron cycling in a global three-dimensional model
NASA Astrophysics Data System (ADS)
Moore, J. Keith; Doney, Scott C.; Lindsay, Keith
2004-12-01
A global three-dimensional marine ecosystem model with several key phytoplankton functional groups, multiple limiting nutrients, explicit iron cycling, and a mineral ballast/organic matter parameterization is run within a global ocean circulation model. The coupled biogeochemistry/ecosystem/circulation (BEC) model reproduces known basin-scale patterns of primary and export production, biogenic silica production, calcification, chlorophyll, macronutrient and dissolved iron concentrations. The model captures observed high nitrate, low chlorophyll (HNLC) conditions in the Southern Ocean, subarctic and equatorial Pacific. Spatial distributions of nitrogen fixation are in general agreement with field data, with total N-fixation of 55 Tg N. Diazotrophs directly account for a small fraction of primary production (0.5%) but indirectly support 10% of primary production and 8% of sinking particulate organic carbon (POC) export. Diatoms disproportionately contribute to export of POC out of surface waters, but CaCO3 from the coccolithophores is the key driver of POC flux to the deep ocean in the model. An iron source from shallow ocean sediments is found critical in preventing iron limitation in shelf regions, most notably in the Arctic Ocean, but has a relatively localized impact. In contrast, global-scale primary production, export production, and nitrogen fixation are all sensitive to variations in atmospheric mineral dust inputs. The residence time for dissolved iron in the upper ocean is estimated to be a few years to a decade. Most of the iron utilized by phytoplankton is from subsurface sources supplied by mixing, entrainment, and ocean circulation. However, owing to the short residence time of iron in the upper ocean, this subsurface iron pool is critically dependent on continual replenishment from atmospheric dust deposition and, to a lesser extent, lateral transport from shelf regions.
Hall effect control of magnetotail dawn-dusk asymmetry: A three-dimensional global hybrid simulation
NASA Astrophysics Data System (ADS)
Lu, San; Lin, Y.; Angelopoulos, V.; Artemyev, A. V.; Pritchett, P. L.; Lu, Quanming; Wang, X. Y.
2016-12-01
Magnetotail reconnection and related phenomena (e.g., flux ropes, dipolarizing flux bundles, flow bursts, and particle injections) occur more frequently on the duskside than on the dawnside. Because this asymmetry can directly result in dawn-dusk asymmetric space weather effects, uncovering its physical origin is important for better understanding, modeling, and prediction of the space weather phenomena. However, the cause of this pervasive asymmetry is unclear. Using three-dimensional global hybrid simulations, we demonstrate that the Hall physics in the magnetotail current sheet is responsible for the asymmetry. The current sheet thins progressively under enhanced global convection; when its thickness reaches ion kinetic scales, some ions are decoupled from the magnetized electrons (the Hall effect). The resultant Hall electric field Ez is directed toward the neutral plane. The Hall effect is stronger (grows faster) on the duskside; i.e., more ions become unmagnetized there and do not comove with the magnetized dawnward Ez × Bx drifting electrons, thus creating a larger additional cross-tail current intensity jy (in addition to the diamagnetic current) on the duskside, compared to the dawnside. The stronger Hall effect strength on the duskside is controlled by the higher ion temperature, thinner current sheet, and smaller normal magnetic field Bz there. These asymmetric current sheet properties are in turn controlled by two competing processes that correspond to the Hall effect: (1) the dawnward E × B drift of the magnetic flux and magnetized ions and electrons and (2) the transient motion of the unmagnetized ions which do not execute E × B drift.
Jiang, Yan-Fei; Stone, James M.; Davis, Shane W.
2014-12-01
We study super-Eddington accretion flows onto black holes using a global three-dimensional radiation magneto-hydrodynamical simulation. We solve the time-dependent radiative transfer equation for the specific intensities to accurately calculate the angular distribution of the emitted radiation. Turbulence generated by the magneto-rotational instability provides self-consistent angular momentum transfer. The simulation reaches inflow equilibrium with an accretion rate ∼220 L {sub Edd}/c {sup 2} and forms a radiation-driven outflow along the rotation axis. The mechanical energy flux carried by the outflow is ∼20% of the radiative energy flux. The total mass flux lost in the outflow is about 29% of the net accretion rate. The radiative luminosity of this flow is ∼10 L {sub Edd}. This yields a radiative efficiency ∼4.5%, which is comparable to the value in a standard thin disk model. In our simulation, vertical advection of radiation caused by magnetic buoyancy transports energy faster than photon diffusion, allowing a significant fraction of the photons to escape from the surface of the disk before being advected into the black hole. We contrast our results with the lower radiative efficiencies inferred in most models, such as the slim disk model, which neglect vertical advection. Our inferred radiative efficiencies also exceed published results from previous global numerical simulations, which did not attribute a significant role to vertical advection. We briefly discuss the implications for the growth of supermassive black holes in the early universe and describe how these results provided a basis for explaining the spectrum and population statistics of ultraluminous X-ray sources.
Flock, M.; Dzyurkevich, N.; Klahr, H.; Turner, N. J.; Henning, Th.
2011-07-10
We present full 2{pi} global three-dimensional stratified magnetohydrodynamic (MHD) simulations of accretion disks. We interpret our results in the context of protoplanetary disks. We investigate the turbulence driven by the magnetorotational 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 in those 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 the calculations because fluctuating radial pressure gradients lead to changes in the orbital frequency, comparable in importance to the stress gradients that drive the meridional flows in viscous models. The net mass flow rate is well reproduced by a viscous model using the mean stress distribution taken from the MHD calculation. The strength of the mean turbulent magnetic field is inversely proportional to the radius, so the fields are approximately force-free on the largest scales. Consequently, the accretion stress falls off as the inverse square of the radius.
A three-dimensional global dynamical and chemical model of methane
Tie, Xuexi.
1990-01-01
A three-dimensional global chemical and dynamical methane model was generated which includes horizontal and vertical advection, diffusion, chemical reactions, and surface release terms. The input winds and sinks vary with the seasons and a lone seasonal variation in the source is introduced to simulate rice paddy release. The calculated results are compared with measured methane horizontal distributions, vertical profiles, latitudinal distributions, and zonal cross sections. The calculated surface horizontal distributions are consistent with methane measurement at 23 stations from about 76 degrees N to the south pole. The calculated surface methane shows a maximum around Asia in the rice harvest season. However, there are essentially no measured methane values in this area to compare with these calculations. In the lower troposphere of the Northern Hemisphere, methane exhibits a seasonal cycle which is mainly driven by the seasonal cycles of the die releases, the chemical sinks, and transport. There are two rice production seasons which produced, according to the calculations, an increase in the methane transport to the northeast of the rice productions areas in eastern Asia. In the lower troposphere of the Southern Hemisphere, the methane seasonal cycle exhibits a maximum in September and a maximum in March which are mainly driven by the seasonal cycles of the chemical sinks. However, in the upper troposphere, the methane cycle is mainly influenced by transport. In the stratosphere, methane flows readily between the Northern Hemisphere and the Southern Hemisphere. The calculated methane has a maximum around 20 degrees N in July and 20 degrees S in January. Methane measured by satellite (Nimbus 7) shows similar spatial and temporal features.
NASA Astrophysics Data System (ADS)
Chicheportiche, Jérèmie; Merle, Xavier; Gloerfelt, Xavier; Robinet, Jean-Christophe
2008-07-01
The first bifurcation in a lid-driven cavity characterized by three-dimensional Taylor-Görtler-Like instabilities is investigated for a cubical cavity with spanwise periodic boundary conditions at Re=1000. The modes predicted by a global linear stability analysis are compared to the results of a direct numerical simulation. The amplification rate, and the shape of the three-dimensional perturbation fields from the direct numerical simulation are in very good agreement with the characteristics of the steady S1 mode from the stability analysis, showing that this mode dominates the other unstable unsteady modes. To cite this article: J. Chicheportiche et al., C. R. Mecanique 336 (2008).
Development of a three-dimensional Navier-Stokes code on CDC star-100 computer
NASA Technical Reports Server (NTRS)
Vatsa, V. N.; Goglia, G. L.
1978-01-01
A three-dimensional code in body-fitted coordinates was developed using MacCormack's algorithm. The code is structured to be compatible with any general configuration, provided that the metric coefficients for the transformation are available. The governing equations are developed in primitive variables in order to facilitate the incorporation of physical boundary conditions and turbulence-closure models. MacCormack's two-step, unsplit, time-marching algorithm is used to solve the unsteady Navier-Stokes equations until steady-state solution is achieved. Cases discussed include (1) flat plate in supersonic free stream; (2) supersonic flow along an axial corner; (3) subsonic flow in an axial corner at M infinity = 0.95; and (4) supersonic flow in an axial corner at M infinity 1.5.
NASA Astrophysics Data System (ADS)
Lin, Y.; Wang, X. Y.; Lu, S.; Perez, J. D.; Lu, Q.
2014-09-01
Dynamics of the near-Earth magnetotail associated with substorms during a period of extended southward interplanetary magnetic field is studied using a three-dimensional (3-D) global hybrid simulation model that includes both the dayside and nightside magnetosphere, for the first time, with physics from the ion kinetic to the global Alfvénic convection scales. It is found that the dayside reconnection leads to the penetration of the dawn-dusk electric field through the magnetopause and thus a thinning of the plasma sheet, followed by the magnetotail reconnection with 3-D, multiple flux ropes. Ion kinetic physics is found to play important roles in the magnetotail dynamics, which leads to the following results: (1) Hall electric fields in the thin current layer cause a systematic dawnward ion drift motion and thus a dawn-dusk asymmetry of the plasma sheet with a higher (lower) density on the dawnside (duskside). Correspondingly, more reconnection occurs on the duskside. Bidirectional fast ions are generated due to acceleration in reconnection, and more high-speed earthward flow injections are found on the duskside than the dawnside. Such finding of the dawn-dusk asymmetry is consistent with recent satellite observations. (2) The injected ions undergo the magnetic gradient and curvature drift in the dipole-like field, forming a ring current. (3) Ion particle distributions reveal multiple populations/beams at various distances in the tail. (4) Dipolarization of the tail magnetic field takes place due to the pileup of the injected magnetic fluxes and thermal pressure of injected ions, where the fast earthward flow is stopped. Oscillation of the dipolarization front is developed at the fast-flow braking, predominantly on the dawnside. (5) Kinetic compressional wave turbulence is present around the dipolarization front. The cross-tail currents break into small-scale structures with k⟂ρi˜1, where k⟂ is the perpendicular wave number. A sharp dip of magnetic field
Brun, A. S. E-mail: palacios@graal.univ-montp2.fr
2009-09-10
With the development of one-dimensional stellar evolution codes including rotation and the increasing number of observational data for stars of various evolutionary stages, it becomes more and more possible to follow the evolution of the rotation profile and angular momentum distribution in stars. In this context, understanding the interplay between rotation and convection in the very extended envelopes of giant stars is very important considering that all low- and intermediate-mass stars become red giants after the central hydrogen burning phase. In this paper, we analyze the interplay between rotation and convection in the envelope of red giant stars using three-dimensional numerical experiments. We make use of the Anelastic Spherical Harmonics code to simulate the inner 50% of the envelope of a low-mass star on the red giant branch. We discuss the organization and dynamics of convection, and put a special emphasis on the distribution of angular momentum in such a rotating extended envelope. To do so, we explore two directions of the parameter space, namely, the bulk rotation rate and the Reynolds number with a series of four simulations. We find that turbulent convection in red giant stars is dynamically rich, and that it is particularly sensitive to the rotation rate of the star. Reynolds stresses and meridional circulation establish various differential rotation profiles (either cylindrical or shellular) depending on the convective Rossby number of the simulations, but they all agree that the radial shear is large. Temperature fluctuations are found to be large and in the slowly rotating cases, a dominant l = 1 temperature dipole influences the convective motions. Both baroclinic effects and turbulent advection are strong in all cases and mostly oppose one another.
A three-dimensional orbit for the binary star Alpha Andromedae
NASA Astrophysics Data System (ADS)
Branham, Richard L., Jr.
2017-01-01
Stars that are both spectroscopic and optical binaries present a means to determine simultaneously the masses of the components and the distance of the system independent of trigonometric parallax. Alpha Andromedae (Alpheratz) represents such a system and, moreover, the primary is the brightest of the mercury-manganese stars. An orbit, based on 42 interferometric observations and 378 radial velocities, is calculated to solve for 10 parameters: the six coefficients of the apparent ellipse, the constant of areal velocity, the systemic velocity, and the semi-amplitudes. From these, one calculates the orbit of the binary, its period and time of periastron passage, the masses of the components, and the distance of the system. The dynamical parallax does not differ greatly from the trigonometric parallax found from Hipparcos.
Wang, Chao; Xu, Yuci; Li, Weihua; Lin, Zhiqun
2016-08-09
The influence of star-like architecture on phase behavior of star-like block copolymer under cylindrical confinement differs largely from the bulk (i.e., nonconfinement). A set of intriguing self-assembled morphologies and the corresponding phase diagrams of star-like (AB)f diblock copolymers with different numbers of arms f (i.e., f = 3, 9, 15, and 21) in four scenarios (ϕA = 0.3 and V0 > 0; ϕA = 0.3 and V0 < 0; ϕA = 0.7 and V0 > 0; and ϕA = 0.7 and V0 < 0 (where ϕA is the volume fraction of A block) and V0 < 0 and V0 > 0 represent that the pore wall of cylindrical confinement prefers the inner A block (i.e., A-preferential) and B block (i.e., B-preferential), respectively) were for the first time scrutinized by employing the pseudospectral method of self-consistent mean-field theory. Surprisingly, a new nanoscopic phase, that is, perforated-lamellae-on-cylinder (denoted PC), was observed in star-like (AB)3 diblock copolymer at ϕA = 0.3 and V0 > 0. With a further increase in f, a single lamellae (denoted L1) was found to possess a larger phase region. Under the confinement of A-preferential wall (i.e., V0 < 0) at ϕA = 0.3, PC phase became metastable and its free energy increased as f increased. Quite intriguingly, when ϕA = 0.7 and V0 > 0, where an inverted cylinder was formed in bulk, the PC phase became stable, and its free energy decreased as f increased, suggesting the propensity to form PC phase under this condition. Moreover, in stark contrast to the phase transition of C1 → L1 → PC (C1, a single cylindrical microdmain) at ϕA = 0.3 and V0 > 0, when subjected to the A-preferential wall (ϕA = 0.7), a different phase transition sequence (i.e., C1 → PC → L1) was identified due to the formation of a double-layer structure. On the basis of our calculations, the influence of star-like architecture on (AB)f diblock copolymer under the imposed cylindrical confinement, particularly the shift of the phase boundaries as a function of f, was thoroughly
Parking simulation of three-dimensional multi-sized star-shaped particles
NASA Astrophysics Data System (ADS)
Zhu, Zhigang; Chen, Huisu; Xu, Wenxiang; Liu, Lin
2014-04-01
The shape and size of particles may have a great impact on the microstructure as well as the physico-properties of particulate composites. However, it is challenging to configure a parking system of particles to a geometrical shape that is close to realistic grains in particulate composites. In this work, with the assistance of x-ray tomography and a spherical harmonic series, we present a star-shaped particle that is close to realistic arbitrary-shaped grains. To realize such a hard particle parking structure, an inter-particle overlapping detection algorithm is introduced. A serial sectioning approach is employed to visualize the particle parking structure for the purpose of justifying the reliability of the overlapping detection algorithm. Furthermore, the validity of the area and perimeter of solids in any arbitrary section of a plane calculated using a numerical method is verified by comparison with those obtained using an image analysis approach. This contribution is helpful to further understand the dependence of the micro-structure and physico-properties of star-shaped particles on the realistic geometrical shape.
Stereographic projection for three-dimensional global discontinuous Galerkin atmospheric modeling
NASA Astrophysics Data System (ADS)
Blaise, Sébastien; Lambrechts, Jonathan; Deleersnijder, Eric
2015-09-01
A method to solve the three-dimensional compressible Navier-Stokes equations on the sphere is suggested, based on a stereographic projection with a high-order mapping of the elements from the stereographic space to the sphere. The projection is slightly modified, in order to take into account the domain thickness without introducing any approximation about the aspect ratio (deep-atmosphere). In a discontinuous Galerkin framework, the elements alongside the equator are exactly represented using a nonpolynomial geometry, in order to avoid the numerical issues associated with the seam connecting the two hemispheres. This is an crucial point, necessary to avoid mass loss and spurious deviations of the velocity. The resulting model is validated on idealized three-dimensional atmospheric test cases on the sphere, demonstrating the good convergence properties of the scheme, its mass conservation, and its satisfactory behavior in terms of accuracy and low numerical dissipation. A simulation is performed on a variable resolution unstructured grid, producing accurate results despite a substantial reduction of the number of elements.
NASA Astrophysics Data System (ADS)
Jacyszyn-Dobrzeniecka, A. M.; Skowron, D. M.; Mróz, P.; Soszyński, I.; Udalski, A.; Pietrukowicz, P.; Skowron, J.; Poleski, R.; Kozłowski, S.; Wyrzykowski, Ł.; Pawlak, M.; Szymański, M. K.; Ulaczyk, K.
2017-03-01
We present a three-dimensional analysis of a sample of 22 859 type ab RR Lyr stars in the Magellanic System from the OGLE-IV Collection of RR Lyr stars. The distance to each object was calculated based on its photometric metallicity and a theoretical relation between color, absolute magnitude and metallicity. The LMC RR Lyr distribution is very regular and does not show any substructures. We demonstrate that the bar found in previous studies may be an overdensity caused by blending and crowding effects. The halo is asymmetrical with a higher stellar density in its north-eastern area, which is also located closer to us. Triaxial ellipsoids were fitted to surfaces of a constant number density. Ellipsoids farther from the LMC center are less elongated and slightly rotated toward the SMC. The inclination and position angle change significantly with the a axis size. The median axis ratio is 1:1.23:1.45. The RR Lyr distribution in the SMC has a very regular, ellipsoidal shape and does not show any substructures or asymmetries. All triaxial ellipsoids fitted to surfaces of a constant number density have virtually the same shape (axis ratio) and are elongated along the line-of-sight. The median axis ratio is 1:1.10:2.13. The inclination angle is very small and thus the position angle is not well defined. We present the distribution of RR Lyr stars in the Magellanic Bridge area, showing that the Magellanic Clouds' halos overlap. A comparison of the distributions of RR Lyr stars and Classical Cepheids shows that the former are significantly more spread and distributed regularly, while the latter are very clumped and form several distinct substructures.
A-star algorithm based path planning for the glasses-free three-dimensional display system
NASA Astrophysics Data System (ADS)
Yang, Bin; Sang, Xinzhu; Xing, Shujun; Cui, Huilong; Yan, Binbin; Yu, Chongxiu; Dou, Wenhua; Xiao, Liquan
2016-10-01
A-Star (A*) algorithm is a heuristic directed search algorithm to evaluate the cost of moving along a particular path in the search space, which can get the shortest path. Here, path planning between any two points on the map is carried out. The STAGE tool is used to manually add way points on the map and determine their spatial location. The adjacent waypoint with a waypoint ID is connected by the line segment to form the navigation graph. A* algorithm can search the navigation graph to find the shortest path from a starting point to the destination. The A* algorithm can restart searching for path from a certain point, and the complex path can be divided in a plurality of frames. Since the navigation graph consists of the movable space, it is considered the obstacle formed by static objects in the scene, and collision detection between the character and static objects is not considered. A-star algorithm based path planning is experimentally demonstrated on a glasses-free three-dimensional display equipment, so that 3D effect of path finding can be perceived.
Three-dimensional global MHD modeling of a coronal mass ejection interacting with the solar wind
NASA Astrophysics Data System (ADS)
An, J.; Inoue, S.; Magara, T.; Lee, H.; Kang, J.; Hayashi, K.; Tanaka, T.; Den, M.
2013-12-01
We developed a three-dimensional (3D) magnetohydrodynamic (MHD) code to reproduce the structure of the solar wind, the propagation of a coronal mass ejection (CME), and the interaction between them. This MHD code is based on the finite volume method and total diminishing (TVD) scheme with an unstructured grid system. In particular, this grid system can avoid the singularity at the north and south poles and relax tight CFL conditions around the poles, both of which would arise in the spherical coordinate system (Tanaka 1995). In this study, we constructed a model of the solar wind driven by the physical values at 50 solar radii obtained from the MHD tomographic method (Hayashi et al. 2003) where an interplanetary scintillation (IPS) observational data is used. By comparing the result to the observational data obtained from the near-Earth OMNI dataset, we confirmed that our simulation reproduces the velocity, temperature and density profiles obtained from the near-Earth OMNI dataset. We then insert a spheromak-type CME (Kataoka et al. 2009) into our solar-wind model and investigate the propagation process of the CME interacting with the solar wind. In particular, we discuss how the magnetic twist accumulated in a CME affects the CME-solar wind interaction.
NASA Astrophysics Data System (ADS)
Collet, R.; Hayek, W.; Asplund, M.; Nordlund, Å.; Trampedach, R.; Gudiksen, B.
2011-04-01
Context. Three-dimensional (3D) radiative hydrodynamic model atmospheres of metal-poor late-type stars are characterized by cooler upper photospheric layers than their one-dimensional counterparts. This property of 3D model atmospheres can dramatically affect the determination of elemental abundances from temperature-sensitive spectral features, with profound consequences on galactic chemical evolution studies. Aims: We investigate whether the cool surface temperatures predicted by 3D model atmospheres of metal-poor stars can be ascribed to approximations in the treatment of scattering during the modelling phase. Methods: We use the Bifrost code to construct 3D model atmospheres of metal-poor stars and test three different ways to handle scattering in the radiative transfer equation. As a first approach, we solve iteratively the radiative transfer equation for the general case of a source function with a coherent scattering term, treating scattering in a correct and consistent way. As a second approach, we solve the radiative transfer equation in local thermodynamic equilibrium approximation, neglecting altogether the contribution of continuum scattering to extinction in the optically thin layers; this has been the default mode in our previous 3D modelling as well as in present Stagger-Code models. As our third and final approach, we treat continuum scattering as pure absorption everywhere, which is the standard case in the 3D modelling by the CO5BOLD collaboration. Results: For all simulations, we find that the second approach produces temperature structures with cool upper photospheric layers very similar to the case in which scattering is treated correctly. In contrast, treating scattering as pure absorption leads instead to significantly hotter and shallower temperature stratifications. The main differences in temperature structure between our published models computed with the Stagger- and Bifrost codes and those generated with the CO5BOLD code can be traced
On global classical solutions of the three dimensional relativistic Vlasov-Darwin system
NASA Astrophysics Data System (ADS)
Li, Xiuting; Zhang, Xianwen
2016-08-01
We study the Cauchy problem of the relativistic Vlasov-Darwin system with generalized variables proposed by Sospedra-Alfonso et al. ["Global classical solutions of the relativistic Vlasov-Darwin system with small Cauchy data: the generalized variables approach," Arch. Ration. Mech. Anal. 205, 827-869 (2012)]. We prove global existence of a non-negative classical solution to the Cauchy problem in three space variables under small perturbation of the initial datum, and as a consequence, we obtain that nearly spherically symmetric solutions with required regularity exist globally in time.
NASA Astrophysics Data System (ADS)
Krivolutsky, A. A.; Cherepanova, L. A.; V'yushkova, T. Yu.; Repnev, A. I.
2015-07-01
We describe the three-dimensional numerical global photochemical model CHARM-I (CHemical Atmospheric Research Model with Ions) and the results of numerical calculations of global distributions of neutral and charged atmospheric trace gases (in the height range of up to 90 km), such as ozone, nitrogen oxides, electrons, and positive and negative ions. This model is an improved version of the CHARM three-dimensional photochemical model of neutral components with additional reactions with the involvement of ions (a total of 200 photochemical reactions). The model incorporates UV-radiation fluxes on the Lyman-α line and galactic cosmic rays as ionizing factors. The neutral components are calculated with the method of "chemical families" and the concentrations of charged components are calculated by the electroneutrality condition at each time step. The spatial transport of chemically active species is described in the model by the Prather scheme. The developed model makes it also possible to take into account solar flares and particle precipitations in the ionospheric D-region.
NASA Astrophysics Data System (ADS)
Alexander, M. Joan
2015-08-01
Satellite limb-sounding methods provide the best global temperature data available for simultaneous measurement of gravity wave horizontal and vertical structures needed to estimate momentum flux and constrain wave effects on general circulation. Gravity waves vary in the three spatial dimensions and time, so the ideal measurement observes all three dimensions at high resolution nearly simultaneously. High Resolution Dynamics Limb Sounder (HIRDLS) measurements give near-simultaneous profiles in close proximity and at high vertical resolution, but these coincident profiles lie only along the plane of the measurement track. Here we combine HIRDLS and radio occultation data sets to obtain three-dimensional properties of gravity waves on a global scale as well as seasonal variations. The results show dramatic changes from previous estimates using either data set alone. Changes include much larger momentum fluxes and latitudinal variations in propagation direction that support an enhanced role for gravity wave forcing of middle atmosphere circulation.
GLOBAL STAR FORMATION REVISITED
Silk, Joseph; Norman, Colin E-mail: norman@stsci.edu
2009-07-20
A general treatment of disk star formation is developed from a dissipative multiphase model, with the dominant dissipation due to cloud collisions. The Schmidt-Kennicutt (SK) law emerges naturally for star-forming disks and starbursts. We predict that there should be an inverse correlation between Tully-Fisher law and SK law residuals. The model is extended to include a multiphase treatment of supernova feedback that leads to a turbulent pressure-regulated generalization of the star formation law and is applicable to gas-rich starbursts. Enhanced pressure, as expected in merger-induced star formation, enhances star formation efficiency. An upper limit is derived for the disk star formation rate in starbursts that depends on the ratio of global ISM to cloud pressures. We extend these considerations to the case where the interstellar gas pressure in the inner galaxy is dominated by outflows from a central active galactic nucleus (AGN). During massive spheroid formation, AGN-driven winds trigger star formation, resulting in enhanced supernova feedback and outflows. The outflows are comparable to the AGN-boosted star formation rate and saturate in the super-Eddington limit. Downsizing of both SMBH and spheroids is a consequence of AGN-driven positive feedback. Bondi accretion feeds the central black hole with a specific accretion rate that is proportional to the black hole mass. AGN-enhanced star formation is mediated by turbulent pressure and relates spheroid star formation rate to black hole accretion rate. The relation between black hole mass and spheroid velocity dispersion has a coefficient (Salpeter time to gas consumption time ratio) that provides an arrow of time. Highly efficient, AGN-boosted star formation can occur at high redshift.
Global strong solution to the three-dimensional liquid crystal flows of Q-tensor model
NASA Astrophysics Data System (ADS)
Xiao, Yao
2017-02-01
A complex hydrodynamic system that models the fluid of nematic liquid crystals in a bounded domain in R3 is studied. The system is a forced incompressible Navier-Stokes equation coupled with a parabolic type equation of Q-tensors. We invoke the maximal regularity of the Stokes operators and parabolic operators in Besov spaces to obtain the local strong solution if the initial Q-tensor is not too "wild". In addition, it is showed that such solution can be extended to a global one if the initial data is a sufficiently small perturbation around the trivial equilibrium state. Finally, it is proved that the global strong solution obtained here is identical to those weak solutions obtained in Paicu and Zarnescu [26].
Mezentsev, Alexandre; Amundson, Sally A.
2011-01-01
Accumulating data suggest that the biological responses to high and low doses of radiation are qualitatively different, necessitating the direct study of low-dose responses to better understand potential risks. Most such studies have used two-dimensional culture systems, which may not fully represent responses in three-dimensional tissues. To gain insight into low-dose responses in tissue, we have profiled global gene expression in EPI-200, a three-dimensional tissue model that imitates the structure and function of human epidermis, at 4, 16 and 24 h after exposure to high (2.5 Gy) and low (0.1 Gy) doses of low-LET protons. The most significant gene ontology groups among genes altered in expression were consistent with effects observed at the tissue level, where the low dose was associated with recovery and tissue repair, while the high dose resulted in loss of structural integrity and terminal differentiation. Network analysis of the significantly responding genes suggested that TP53 dominated the response to 2.5 Gy, while HNF4A, a novel transcription factor not previously associated with radiation response, was most prominent in the low-dose response. HNF4A protein levels and phosphorylation were found to increase in tissues and cells after low- but not high-dose irradiation. PMID:21486161
Stancliffe, Richard J.; Lattanzio, John C.; Heap, Stuart A.; Campbell, Simon W.; Dearborn, David S. P.
2011-12-01
We use the three-dimensional (3D) stellar structure code DJEHUTY to model the ingestion of protons into the intershell convection zone of a 1 M{sub Sun} asymptotic giant branch star of metallicity Z = 10{sup -4}. We have run two simulations: a low-resolution one of around 300,000 zones and a high-resolution one consisting of 2,000,000 zones. Both simulations have been evolved for about 4 hr of stellar time. We observe the existence of fast, downward flowing plumes that are able to transport hydrogen into close proximity to the helium-burning shell before burning takes place. The intershell in the 3D model is richer in protons than the 1D model by several orders of magnitude and so we obtain substantially higher hydrogen-burning luminosities-over 10{sup 8} L{sub Sun} in the high-resolution simulation-than are found in the 1D model. Convective velocities in these simulations are over ten times greater than the predictions of mixing length theory, though the 3D simulations have greater energy generation due to the enhanced hydrogen burning. We find no evidence of the convective zone splitting into two, though this could be as a result of insufficient spatial resolution or because the models have not been evolved for long enough. We suggest that the 1D mixing length theory and particularly the use of a diffusion algorithm for mixing do not give an accurate picture of these events. An advective mixing scheme may give a better representation of the transport processes seen in the 3D models.
Calibrating a global three-dimensional biogeochemical ocean model (MOPS-1.0)
NASA Astrophysics Data System (ADS)
Kriest, Iris; Sauerland, Volkmar; Khatiwala, Samar; Srivastav, Anand; Oschlies, Andreas
2017-01-01
Global biogeochemical ocean models contain a variety of different biogeochemical components and often much simplified representations of complex dynamical interactions, which are described by many ( ≈ 10 to ≈ 100) parameters. The values of many of these parameters are empirically difficult to constrain, due to the fact that in the models they represent processes for a range of different groups of organisms at the same time, while even for single species parameter values are often difficult to determine in situ. Therefore, these models are subject to a high level of parametric uncertainty. This may be of consequence for their skill with respect to accurately describing the relevant features of the present ocean, as well as their sensitivity to possible environmental changes. We here present a framework for the calibration of global biogeochemical ocean models on short and long timescales. The framework combines an offline approach for transport of biogeochemical tracers with an estimation of distribution algorithm (Covariance Matrix Adaption Evolution Strategy, CMA-ES). We explore the performance and capability of this framework by five different optimizations of six biogeochemical parameters of a global biogeochemical model, simulated over 3000 years. First, a twin experiment explores the feasibility of this approach. Four optimizations against a climatology of observations of annual mean dissolved nutrients and oxygen determine the extent to which different setups of the optimization influence model fit and parameter estimates. Because the misfit function applied focuses on the large-scale distribution of inorganic biogeochemical tracers, parameters that act on large spatial and temporal scales are determined earliest, and with the least spread. Parameters more closely tied to surface biology, which act on shorter timescales, are more difficult to determine. In particular, the search for optimum zooplankton parameters can benefit from a sound knowledge of
Application of a global variational analysis to quasi three-dimensional temperature retrievals
NASA Technical Reports Server (NTRS)
Dalcher, A.; Kalnay, E.; Halem, M.
1983-01-01
The Halen and Kalnay (1983) hypothesis that the application of global variational analysis to clear column radiances will result in a reduction of both observational noise and data gaps is tested, together with the hypothesis of these authors that the estimate of clear column radiances furnished by the variational analysis can yield a useful reduction of the data gaps in the retrieved temperatures. In the first of two experiments conducted, attention is given to whether the nonlinearity of the temperature retrieval method is sufficiently strong to result in more accurate temperature retrievals. In the second experiment, realistic subgrid scale cloud fields and observational and temperature errors are included in the simulation system.
Mitchell, B.
1990-12-01
A one-dimensional radiative transfer model was used to compute the global radiative budget at the top of the atmosphere (TOA) and the surface for January and July. 1979. The model was also used to determine the global cloud radiative forcing for all clouds and for high and low cloud layers. In the computations. the authors used the monthly cloud data derived from the Air Force Three-Dimensional Cloud Nephanalysis (3DNEPH). These data were used in conjunction with conventional temperature and humidity profiles analyzed during the 1979 First GARP (Global Atmospheric Research Program) Global Experiment (FGGE) year. Global surface albedos were computed from available data and were included in the radiative transfer analysis. Comparisons of the model-produced outgoing solar and infrared fluxes with those derived from Nimbus 7 Earth Radiation Budget (ERS) data were made to validate the radiative model and cloud cover. For reflected solar and emitted infrared (IR) flux, differences within 20 w/sq m meters were shown.
Leek, E Charles; Roberts, Mark; Oliver, Zoe J; Cristino, Filipe; Pegna, Alan J
2016-08-01
Here we investigated the time course underlying differential processing of local and global shape information during the perception of complex three-dimensional (3D) objects. Observers made shape matching judgments about pairs of sequentially presented multi-part novel objects. Event-related potentials (ERPs) were used to measure perceptual sensitivity to 3D shape differences in terms of local part structure and global shape configuration - based on predictions derived from hierarchical structural description models of object recognition. There were three types of different object trials in which stimulus pairs (1) shared local parts but differed in global shape configuration; (2) contained different local parts but shared global configuration or (3) shared neither local parts nor global configuration. Analyses of the ERP data showed differential amplitude modulation as a function of shape similarity as early as the N1 component between 146-215ms post-stimulus onset. These negative amplitude deflections were more similar between objects sharing global shape configuration than local part structure. Differentiation among all stimulus types was reflected in N2 amplitude modulations between 276-330ms. sLORETA inverse solutions showed stronger involvement of left occipitotemporal areas during the N1 for object discrimination weighted towards local part structure. The results suggest that the perception of 3D object shape involves parallel processing of information at local and global scales. This processing is characterised by relatively slow derivation of 'fine-grained' local shape structure, and fast derivation of 'coarse-grained' global shape configuration. We propose that the rapid early derivation of global shape attributes underlies the observed patterns of N1 amplitude modulations.
Optimal estimation of regional N2O emissions using a three-dimensional global model
NASA Astrophysics Data System (ADS)
Huang, J.; Golombek, A.; Prinn, R.
2004-12-01
In this study, we use the MATCH (Model of Atmospheric Transport and Chemistry) model and Kalman filtering techniques to optimally estimate N2O emissions from seven source regions around the globe. The MATCH model was used with NCEP assimilated winds at T62 resolution (192 longitude by 94 latitude surface grid, and 28 vertical levels) from July 1st 1996 to December 31st 2000. The average concentrations of N2O in the lowest four layers of the model were then compared with the monthly mean observations from six national/global networks (AGAGE, CMDL (HATS), CMDL (CCGG), CSIRO, CSIR and NIES), at 48 surface sites. A 12-month-running-mean smoother was applied to both the model results and the observations, due to the fact that the model was not able to reproduce the very small observed seasonal variations. The Kalman filter was then used to solve for the time-averaged regional emissions of N2O for January 1st 1997 to June 30th 2000. The inversions assume that the model stratospheric destruction rates, which lead to a global N2O lifetime of 130 years, are correct. It also assumes normalized emission spatial distributions from each region based on previous studies. We conclude that the global N2O emission flux is about 16.2 TgN/yr, with {34.9±1.7%} from South America and Africa, {34.6±1.5%} from South Asia, {13.9±1.5%} from China/Japan/South East Asia, {8.0±1.9%} from all oceans, {6.4±1.1%} from North America and North and West Asia, {2.6±0.4%} from Europe, and {0.9±0.7%} from New Zealand and Australia. The errors here include the measurement standard deviation, calibration differences among the six groups, grid volume/measurement site mis-match errors estimated from the model, and a procedure to account approximately for the modeling errors.
Evaluation and intercomparison of three-dimensional global marine carbon cycle models
Caldeira, K., LLNL
1998-07-01
The addition of carbon dioxide to the atmosphere from fossil fuel burning and deforestation has profound implications for the future of the earth`s climate and hence for humankind itself. Society is looking toward the community of environmental scientists to predict the consequences of increased atmospheric carbon dioxide so that sound input can be provided to economists, environmental engineers, and, ultimately, policy makers. Environmental scientists have responded to this challenge through the creation of several ambitious, highly-coordinated programs, each focused on a different aspect of the climate system. Recognizing that numerical models, be they relatively simple statistical-empirical models or highly complex process-oriented models, are the only means for predicting the future of the climate system, all of these programs include the development of accurate, predictive models as a central goal. The Joint Global Ocean Flux Study (JGOFS) is one such program, and was built on the well-founded premise that biological, chemical and physical oceanographic processes have a profound influence on the C0{sub 2} content of the atmosphere. The, cap-stone, phase of JGOFS, the Synthesis and Modeling Project (SMP), is charged with the development of models that can be used in the prediction of future air-sea partitioning of C0{sub 2}. JGOFS, particularly the SMP phase, has a number of interim goals as well, including the determination of fluxes and inventories of carbon in the modern ocean that air germane to the air-sea partitioning of C0{sub 2}. Models have a role to play here too, because many of these fluxes and inventories, such as the distributions of anthropogenic dissolved inorganic carbon (DIC), new primary production and aphotic zone remineralization, while not amenable to direct observation on the large scale, can be determined using a variety of modeling approaches (Siegenthaler and Oeschger, 1987; Maier-Reimer and Hasselman, 1987, Bacastow and Maier
NASA Technical Reports Server (NTRS)
Kuznetsova, M.M.; Sibeck, D.; Hesse, M.; Rastatter, L.; Toth, G.
2008-01-01
We performed high resolution global MHD simulations of THEMIS dayside crossings events in May -June 2007. We found that magnetopause surface is not in steady-state even during extended periods of steady solar wind conditions. The so-called tilted reconnection lines become unstable due to formation of pressure bubbles, strong core field flux tubes, vortices, and traveling magnetic field cavities. The topology of FTEs differ from that in two dimension cartoons representing obliquely oriented quasi-2D flux rope. The structure of FTE is changing at spatial scales of 1 -2 Re. Closely located space probes can observe completely different signatures. Branches of bent flux rope can move in opposite directions. THEMIS and Cluster observations are consistent with signatures predicted by simulations.
Atherton, C.S.
1995-01-05
Two of the most important chemically reactive tropospheric gases are ozone (O{sub 3}) and the hydroxyl radical (OH). Although ozone in the stratosphere is a necessary protector against the sun`s radiation, tropospheric ozone is actually a pollutant which damages materials and vegetation, acts as a respiratory irritant, and is a greenhouse gas. One of the two main sources of ozone in the troposphere is photochemical production. The photochemistry is initiated when hydrocarbons and carbon monoxide (CO) react with nitrogen oxides (NO{sub x} = NO + NO{sub 2}) in the presence of sunlight. Reaction with the hydroxyl radical, OH, is the main sink for many tropospheric gases. The hydroxyl radical is highly reactive and has a lifetime on the order of seconds. Its formation is initiated by the photolysis of tropospheric ozone. Tropospheric chemistry involves a complex, non-linear set of chemical reactions between atmospheric species that vary substantially in time and space. To model these and other species on a global scale requires the use of a global, three-dimensional chemistry, transport, and deposition (CTD) model. In this work, I developed two such three dimensional CTD models. The first model incorporated the chemistry necessary to model tropospheric ozone production from the reactions of nitrogen oxides with carbon monoxide (CO) and methane (CH{sub 4}). The second also included longer-lived alkane species and the biogenic hydrocarbon isoprene, which is emitted by growing plants and trees. The models` ability to predict a number of key variables (including the concentration of O{sub 3}, OH, and other species) were evaluated. Then, several scenarios were simulated to understand the change in the chemistry of the troposphere since preindustrial times and the role of anthropogenic NO{sub x} on present day conditions.
NASA Astrophysics Data System (ADS)
Zimmerman, M. I.; Hsieh, S. W.; Brandt, P. C.; Vandegriff, J. D.; Stephens, G. K.; Toigo, A. D.; Keika, K.; Kusterer, M. B.; Demajistre, R.
2013-12-01
Extreme Ultra Violet (EUV) and Energetic neutral atom (ENA) imaging are powerful remote sensing tools utilized on, for example the IMAGE and TWINS missions, that provides global three-dimensional information about the structure, dynamics, and composition of Earth's plasmaspheric He+ and ring current ion distributions. Numerical retrieval techniques provide 3D distributions of quantities such as pressure and ion flux from ring current ENA images and the He+ distribution from EUV plasmasphere images. The tool includes an intuitive interface wnabling the user to select from a variety of prepared datasets, display and manipulate nested pressure isocontours, depict coincident spacecraft tracks and compare in-situ data with global distributions derived from images, and animate the pressure evolution of a magnetospheric storm. Therefore the tool is valuable for the validation and intercomparison between global and in-situ data and is broadly applicable to other derived global datasets and modeling results. Screenshot of the visualization tool including 3D isocontours of pressure inferred from IMAGE/HENA inversion data (left panel) and the equatorial inverted image intensity (right panel).
THREE-DIMENSIONAL KINETIC-MHD MODEL OF THE GLOBAL HELIOSPHERE WITH THE HELIOPAUSE-SURFACE FITTING
Izmodenov, V. V.; Alexashov, D. B.
2015-10-15
This paper provides a detailed description of the latest version of our model of the solar wind (SW) interaction with the local interstellar medium (LISM). This model has already been applied to the analysis of Lyα absorption spectra toward nearby stars and for analyses of Solar and Heliospheric Observatory/SWAN data. Katushkina et al. (this issue) used the model results to analyze IBEX-Lo data. At the same time, the details of this model have not yet been published. This is a three-dimensional (3D) kinetic-magnetohydrodynamical (MHD) model that takes into account SW and interstellar plasmas (including α particles in SW and helium ions in LISM), the solar and interstellar magnetic fields, and interstellar hydrogen atoms. The latitudinal dependence of SW and the actual flow direction of the interstellar gas with respect to the Sun are also taken into account in the model. It was very essential that our numerical code was developed in such a way that any numerical diffusion or reconnection across the heliopause were not allowed in the model. The heliospheric current sheet is a rotational discontinuity in the ideal MHD and can be treated kinematically. In the paper, we focus in particular on the effects of the heliospheric magnetic field and on the heliolatitudinal dependence of SW.
Wang, Hsiang-Hsu; Shang, Hsien; Gu, Pin-Gao; Bu, Defu
2014-07-20
The regular satellites found around Neptune (≈17 M{sub ⊕}) and Uranus (≈14.5 M{sub ⊕}) suggest that past gaseous circumplanetary disks may have co-existed with solids around sub-Neptune-mass protoplanets (<17 M{sub ⊕}). These disks have been shown to be cool, optically thin, and quiescent, with low surface densities and low viscosities. Numerical studies of the formation are difficult and technically challenging. As an introductory attempt, three-dimensional global simulations are performed to explore the formation of circumplanetary disks around sub-Neptune-mass protoplanets embedded within an isothermal protoplanetary disk at the inviscid limit of the fluid in the absence of self-gravity. Under such conditions, a sub-Neptune-mass protoplanet can reasonably have a rotationally supported circumplanetary disk. The size of the circumplanetary disk is found to be roughly one-tenth of the corresponding Hill radius, which is consistent with the orbital radii of irregular satellites found for Uranus. The protoplanetary gas accretes onto the circumplanetary disk vertically from high altitude and returns to the protoplanetary disk again near the midplane. This implies an open system in which the circumplanetary disk constantly exchanges angular momentum and material with its surrounding prenatal protoplanetary gas.
NASA Astrophysics Data System (ADS)
Riley, Douglas A.
We study the three-dimensional incompressible Navier- Stokes equations in a domain of the form W'×(0,e) . First, we assume W' is a C3 bounded domain and impose no-slip boundary conditions on 6W'×(0,e ) , and periodic conditions on W'×
Agosti, Valeria; Vitale, Carmine; Avella, Dario; Rucco, Rosaria; Santangelo, Gabriella; Sorrentino, Pierpaolo; Varriale, Pasquale; Sorrentino, Giuseppe
2016-04-01
The Global Postural Reeducation (GPR) method is a physical therapy based on the stretching of antigravity muscle chains with the parallel enhancement of the basal tone of antagonistic muscles addressed to improve static and dynamic stability. Through a three-dimensional motion analysis (3DMA) system, our study aims to investigate whether in Parkinson's disease (PD) patients a GPR program results in a more physiological gait pattern. The kinematic parameters of gait of twenty subjects with clinically diagnosed PD were calculated. The patients were randomly assigned to a study (10 or control (10) group. All subjects underwent neurological and 3DMA assessments at entry time (t 0), at 4 weeks (t 1, end of GPR program), and at 8 and 12 weeks (t 2 and t 3, follow-up evaluation). The study group underwent a four-week GPR program, three times a week, for 40 min individual sessions. Kinematic gait parameters of thigh (T), knee (K) and ankle (A) and UPDRS-III scores were evaluated. At the end of the GPR program, we observed an improvement of the kinematic gait pattern, documented by the increase in KΔc and TΔc values that respectively express the flexion amplitude of knee and thigh. The amelioration was persistent at follow-up assessments, with a parallel enhancement in clinical parameters. GPR intervention shows a long-term efficacy on gait pattern in PD patients. Furthermore, we validated 3DMA as a valuable tool to study the kinematics of gait thus refining the understanding of the effects of specific rehabilitation programs.
NASA Technical Reports Server (NTRS)
Balkanski, Yves J.; Jacob, Daniel J.; Gardner, Geraldine M.; Graustein, William C.; Turekian, Karl K.
1993-01-01
A global three-dimensional model is used to investigate the transport and tropospheric residence time of Pb-210, an aerosol tracer produced in the atmosphere by radioactive decay of Rn-222 emitted from soils. The model uses meteorological input with 4 deg x 5 deg horizontal resolution and 4-hour temporal resolution from the Goddard Institute for Space Studies general circulation model (GCM). It computes aerosol scavenging by convective precipitation as part of the wet convective mass transport operator in order to capture the coupling between vertical transport and rainout. Scavenging in convective precipitation accounts for 74% of the global Pb-210 sink in the model; scavenging in large-scale precipitation accounts for 12%, and scavenging in dry deposition accounts for 14%. The model captures 63% of the variance of yearly mean Pb-210 concentrations measured at 85 sites around the world with negligible mean bias, lending support to the computation of aerosol scavenging. There are, however, a number of regional and seasonal discrepancies that reflect in part anomalies in GCM precipitation. Computed residence times with respect to deposition for Pb-210 aerosol in the tropospheric column are about 5 days at southern midlatitudes and 10-15 days in the tropics; values at northern midlatitudes vary from about 5 days in winter to 10 days in summer. The residence time of Pb-210 produced in the lowest 0.5 km of atmosphere is on average four times shorter than that of Pb-210 produced in the upper atmosphere. Both model and observations indicate a weaker decrease of Pb-210 concentrations between the continental mixed layer and the free troposphere than is observed for total aerosol concentrations; an explanation is that Rn-222 is transported to high altitudes in wet convective updrafts, while aerosols and soluble precursors of aerosols are scavenged by precipitation in the updrafts. Thus Pb-210 is not simply a tracer of aerosols produced in the continental boundary layer, but
Lopez-Camara, D.; Lazzati, Davide; Morsony, Brian J.; Begelman, Mitchell C.
2013-04-10
We present the results of special relativistic, adaptive mesh refinement, 3D simulations of gamma-ray burst jets expanding inside a realistic stellar progenitor. Our simulations confirm that relativistic jets can propagate and break out of the progenitor star while remaining relativistic. This result is independent of the resolution, even though the amount of turbulence and variability observed in the simulations is greater at higher resolutions. We find that the propagation of the jet head inside the progenitor star is slightly faster in 3D simulations compared to 2D ones at the same resolution. This behavior seems to be due to the fact that the jet head in 3D simulations can wobble around the jet axis, finding the spot of least resistance to proceed. Most of the average jet properties, such as density, pressure, and Lorentz factor, are only marginally affected by the dimensionality of the simulations and therefore results from 2D simulations can be considered reliable.
NASA Astrophysics Data System (ADS)
Nucci, M. C.; Busso, M.
2014-06-01
The advection of thermonuclear ashes by magnetized domains emerging near the H shell was suggested to explain asymptotic giant branch (AGB) star abundances. Here we verify this idea quantitatively through exact MHD models. Starting with a simple two-dimensional (2D) geometry and in an inertia frame, we study plasma equilibria avoiding the complications of numerical simulations. We show that below the convective envelope of an AGB star, variable magnetic fields induce a natural expansion, permitted by the almost ideal MHD conditions, in which the radial velocity grows as the second power of the radius. We then study the convective envelope, where the complexity of macroturbulence allows only for a schematic analytical treatment. Here the radial velocity depends on the square root of the radius. We then verify the robustness of our results with 3D calculations for the velocity, showing that for both studied regions the solution previously found can be seen as a planar section of a more complex behavior, in which the average radial velocity retains the same dependency on the radius found in 2D. As a final check, we compare our results to approximate descriptions of buoyant magnetic structures. For realistic boundary conditions, the envelope crossing times are sufficient to disperse in the huge convective zone any material transported, suggesting magnetic advection as a promising mechanism for deep mixing. The mixing velocities are smaller than for convection but larger than for diffusion and adequate for extra mixing in red giants.
Balavigneswaran, Chelladurai Karthikeyan; Mahto, Sanjeev Kumar; Subia, Bano; Prabhakar, Arumugam; Mitra, Kheyanath; Rao, Vivek; Ganguli, Munia; Ray, Biswajit; Maiti, Pralay; Misra, Nira
2017-04-10
Biodegradable poly(lactic acid) (PLA) is widely used to fabricate 3D scaffolds for tissue regeneration. However, PLA lacks cell adhering functional moieties, which limit its successful application in tissue engineering. Herein, we have tailored the cell adhesive properties of star shaped poly(d,l-lactide) (ss-PDLLA) by grafting gelatin to their 4 arms. Grafting of gelatin on PDLLA backbone was confirmed by (1)H NMR and FTIR. The synthesized star shaped poly(d,l-lactide)-b-gelatin (ss-pLG) exhibited enhanced wettability and protein adsorption. The modification also facilitated better cell adhesion and proliferation on their respective polymer coated 2D substrates, compared to their respective unmodified ss-PDLLA. Further, 3D scaffolds were fabricated from gelatin grafted and unmodified polymers. The fabricated scaffolds were shown to be cytocompatible to 3T3-L1 cells and hemocompatible to red blood cells (RBCs). Cell proliferation was increased up to 2.5-fold in ss-pLG scaffolds compared to ss-PDLLA scaffolds. Furthermore, a significant increase in cell number reveals a high degree of infiltration of cells into the scaffolds, forming a viable and healthy 3D interconnected cell community. In addition to that, burst release of docetaxal (DTX) was observed from ss-pLG scaffolds. Hence, this new system of grafting polymers followed by fabricating 3D scaffolds could be utilized as a successful approach in a variety of applications where cell-containing depots are used.
Nucci, M. C.; Busso, M. E-mail: busso@fisica.unipg.it
2014-06-01
The advection of thermonuclear ashes by magnetized domains emerging near the H shell was suggested to explain asymptotic giant branch (AGB) star abundances. Here we verify this idea quantitatively through exact MHD models. Starting with a simple two-dimensional (2D) geometry and in an inertia frame, we study plasma equilibria avoiding the complications of numerical simulations. We show that below the convective envelope of an AGB star, variable magnetic fields induce a natural expansion, permitted by the almost ideal MHD conditions, in which the radial velocity grows as the second power of the radius. We then study the convective envelope, where the complexity of macroturbulence allows only for a schematic analytical treatment. Here the radial velocity depends on the square root of the radius. We then verify the robustness of our results with 3D calculations for the velocity, showing that for both studied regions the solution previously found can be seen as a planar section of a more complex behavior, in which the average radial velocity retains the same dependency on the radius found in 2D. As a final check, we compare our results to approximate descriptions of buoyant magnetic structures. For realistic boundary conditions, the envelope crossing times are sufficient to disperse in the huge convective zone any material transported, suggesting magnetic advection as a promising mechanism for deep mixing. The mixing velocities are smaller than for convection but larger than for diffusion and adequate for extra mixing in red giants.
Bisikalo, D.; Kaygorodov, P.; Ionov, D.; Shematovich, V.; Lammer, H.; Fossati, L.
2013-02-10
Hubble Space Telescope transit observations in the near-UV performed in 2009 made WASP-12b one of the most 'mysterious' exoplanets; the system presents an early ingress, which can be explained by the presence of optically thick matter located ahead of the planet at a distance of {approx}4-5 planet radii. This work follows previous attempts to explain this asymmetry with an exospheric outflow or a bow shock, induced by a planetary magnetic field, and provides a numerical solution of the early ingress, though we did not perform any radiative transfer calculation. We performed pure 3D gas dynamic simulations of the plasma interaction between WASP-12b and its host star and describe the flow pattern in the system. In particular, we show that the overfilling of the planet's Roche lobe leads to a noticeable outflow from the upper atmosphere in the direction of the L{sub 1} and L{sub 2} points. Due to the conservation of the angular momentum, the flow to the L{sub 1} point is deflected in the direction of the planet's orbital motion, while the flow toward L{sub 2} is deflected in the opposite direction, resulting in a non-axisymmetric envelope, surrounding the planet. The supersonic motion of the planet inside the stellar wind leads to the formation of a bow shock with a complex shape. The existence of the bow shock slows down the outflow through the L{sub 1} and L{sub 2} points, allowing us to consider a long-living flow structure that is in the steady state.
Three dimensional strained semiconductors
Voss, Lars; Conway, Adam; Nikolic, Rebecca J.; Leao, Cedric Rocha; Shao, Qinghui
2016-11-08
In one embodiment, an apparatus includes a three dimensional structure comprising a semiconductor material, and at least one thin film in contact with at least one exterior surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the three dimensional structure. In another embodiment, a method includes forming a three dimensional structure comprising a semiconductor material, and depositing at least one thin film on at least one surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the structure.
Kulinskii, V L
2010-10-07
We analyze the interrelation between the coexistence curve of the Lennard-Jones fluid and the Ising model in two and three dimensions within the global isomorphism approach proposed earlier [V. L. Kulinskii, J. Phys. Chem. B 114, 2852 (2010)]. In case of two dimensions, we use the exact Onsager result to construct the binodal of the corresponding Lennard-Jones fluid and compare it with the results of the simulations. In the three-dimensional case, we use available numerical results for the Ising model for the corresponding mapping. The possibility to observe the singularity of the binodal diameter is discussed.
NASA Technical Reports Server (NTRS)
Douglass, Anne R.; Rood, Richard B.; Jackman, Charles H.; Weaver, Clark J.
1994-01-01
Two-dimensional (zonally averaged) photochemical models are commonly used for calculations of ozone changes due to various perturbations. These include calculating the ozone change expected as a result of change in the lower stratospheric composition due to the exhaust of a fleet of supersonic aircraft flying in the lower stratosphere. However, zonal asymmetries are anticipated to be important to this sort of calculation. The aircraft are expected to be restricted from flying over land at supersonic speed due to sonic booms, thus the pollutant source will not be zonally symmetric. There is loss of pollutant through stratosphere/troposphere exchange, but these processes are spatially and temporally inhomogeneous. Asymmetry in the pollutant distribution contributes to the uncertainty in the ozone changes calculated with two dimensional models. Pollutant distributions for integrations of at least 1 year of continuous pollutant emissions along flight corridors are calculated using a three dimensional chemistry and transport model. These distributions indicate the importance of asymmetry in the pollutant distributions to evaluation of the impact of stratospheric aircraft on ozone. The implications of such pollutant asymmetries to assessment calculations are discussed, considering both homogeneous and heterogeneous reactions.
Richards, Mercedes T.; Agafonov, Michail I.; Sharova, Olga I. E-mail: agfn@nirfi.sci-nnov.ru
2012-11-20
Time-resolved H{alpha} spectra of magnetically active interacting binaries have been used to create three-dimensional (3D) Doppler tomograms by means of the Radioastronomical Approach. This is the first 3D reconstruction of {beta} Per, with RS Vul for comparison. These 3D tomograms have revealed evidence of the mass transfer process (gas stream, circumprimary emission, localized region, absorption zone), as well as loop prominences and coronal mass ejections (CMEs) in {beta} Per and RS Vul that could not be discovered from two-dimensional tomograms alone. The gas stream in both binaries may have been deflected beyond the central plane by the donor star's magnetic field. The stream was more elongated along the predicted trajectory in RS Vul than in {beta} Per, but not as pronounced as in U CrB (stream state). The loop prominence reached maximum V{sub z} velocities of {+-}155 km s{sup -1} in RS Vul compared to {+-}120 km s{sup -1} in {beta} Per, while the CME reached a maximum V{sub z} velocity of +150 km s{sup -1} in RS Vul and +100 km s{sup -1} in {beta} Per. The 3D tomograms show that the gas flows are not symmetric relative to the central plane and are not confined to that plane, a result confirmed by recent 15 GHz VLBI radio images of {beta} Per. Both the 3D H{alpha} tomography and the VLBI radio images support an earlier prediction of the superhump phenomenon in {beta} Per: that the gas between the stars is threaded with a magnetic field even though the hot B8V mass-gaining star is not known to have a magnetic field.
Lyra, Wladimir; Mac Low, Mordecai-Mark E-mail: mordecai@amnh.org
2012-09-01
It has been suggested that the transition between magnetorotationally active and dead zones in protoplanetary disks should be prone to the excitation of vortices via Rossby wave instability (RWI). However, the only numerical evidence for this has come from alpha disk models, where the magnetic field evolution is not followed, and the effect of turbulence is parameterized by Laplacian viscosity. We aim to establish the phenomenology of the flow in the transition in three-dimensional resistive-magnetohydrodynamical models. We model the transition by a sharp jump in resistivity, as expected in the inner dead zone boundary, using the PENCIL CODE to simulate the flow. We find that vortices are readily excited in the dead side of the transition. We measure the mass accretion rate finding similar levels of Reynolds stress at the dead and active zones, at the {alpha} Almost-Equal-To 10{sup -2} level. The vortex sits in a pressure maximum and does not migrate, surviving until the end of the simulation. A pressure maximum in the active zone also triggers the RWI. The magnetized vortex that results should be disrupted by parasitical magneto-elliptic instabilities, yet it subsists in high resolution. This suggests that either the parasitic modes are still numerically damped or that the RWI supplies vorticity faster than they can destroy it. We conclude that the resistive transition between the active and dead zones in the inner regions of protoplanetary disks, if sharp enough, can indeed excite vortices via RWI. Our results lend credence to previous works that relied on the alpha-disk approximation, and caution against the use of overly reduced azimuthal coverage on modeling this transition.
Thorstensen, Anders; Dalen, Håvard; Hala, Pavel; Kiss, Gabriel; D'hooge, Jan; Torp, Hans; Støylen, Asbjørn; Amundsen, Brage
2013-07-01
We aimed to compare three-dimensional (3D) and two-dimensional (2D) echocardiography in the evaluation of patients with recent myocardial infarction (MI), using late-enhancement magnetic resonance imaging (LE-MRI) as a reference method. Echocardiography and LE-MRI were performed approximately 1 month after first-time MI in 58 patients. Echocardiography was also performed on 35 healthy controls. Left ventricular (LV) ejection fraction by 3D echocardiography (3D-LVEF), 3D wall-motion score (WMS), 2D-WMS, 3D speckle tracking-based longitudinal, circumferential, transmural and area strain, and 2D speckle tracking-based longitudinal strain (LS) were measured. The global correlations to infarct size by LE-MRI were significantly higher (P < 0.03) for 3D-WMS and 2D-WMS compared with 3D-LVEF and the 4 different measurements of 3D strain, and 2D global longitudinal strain (GLS) was more closely correlated to LE-MRI than 3D GLS (P < 0.03). The segmental correlations to infarct size by LE-MRI were also significantly higher (P < 0.04) for 3D-WMS, 2D-WMS, and 2D LS compared with the other indices. Three-dimensional WMS showed a sensitivity of 76% and a specificity of 72% for identification of LV infarct size >12%, and a sensitivity of 73% and a specificity of 95% for identification of segments with transmural infarct extension. Three-dimensional WMS and 2D gray-scale echocardiography showed the strongest correlations to LE-MRI. The tested 3D strain method suffers from low temporal and spatial resolution in 3D acquisitions and added diagnostic value could not be proven.
NASA Astrophysics Data System (ADS)
Xiao, X.; Prinn, R. G.; Fraser, P. J.; Weiss, R. F.; Simmonds, P. G.; O'Doherty, S.; Miller, B. R.; Salameh, P. K.; Harth, C. M.; Krummel, P. B.; Golombek, A.; Porter, L. W.; Butler, J. H.; Elkins, J. W.; Dutton, G. S.; Hall, B. D.; Steele, L. P.; Wang, R. H. J.; Cunnold, D. M.
2010-11-01
Carbon tetrachloride (CCl4) has substantial stratospheric ozone depletion potential and its consumption is controlled under the Montreal Protocol and its amendments. We implement a Kalman filter using atmospheric CCl4 measurements and a 3-dimensional chemical transport model to estimate the interannual regional industrial emissions and seasonal global oceanic uptake of CCl4 for the period of 1996-2004. The Model of Atmospheric Transport and Chemistry (MATCH), driven by offline National Center for Environmental Prediction (NCEP) reanalysis meteorological fields, is used to simulate CCl4 mole fractions and calculate their sensitivities to regional sources and sinks using a finite difference approach. High frequency observations from the Advanced Global Atmospheric Gases Experiment (AGAGE) and the Earth System Research Laboratory (ESRL) of the National Oceanic and Atmospheric Administration (NOAA) and low frequency flask observations are together used to constrain the source and sink magnitudes, estimated as factors that multiply the a priori fluxes. Although industry data imply that the global industrial emissions were substantially declining with large interannual variations, the optimized results show only small interannual variations and a small decreasing trend. The global surface CCl4 mole fractions were declining in this period because the CCl4 oceanic and stratospheric sinks exceeded the industrial emissions. Compared to the a priori values, the inversion results indicate substantial increases in industrial emissions originating from the South Asian/Indian and Southeast Asian regions, and significant decreases in emissions from the European and North American regions.
NASA Astrophysics Data System (ADS)
Xiao, X.; Prinn, R. G.; Fraser, P. J.; Weiss, R. F.; Simmonds, P. G.; O'Doherty, S.; Miller, B. R.; Salameh, P. K.; Harth, C. M.; Krummel, P. B.; Golombek, A.; Porter, L. W.; Elkins, J. W.; Dutton, G. S.; Hall, B. D.; Steele, L. P.; Wang, R. H. J.; Cunnold, D. M.
2010-05-01
Carbon tetrachloride (CCl4) has substantial stratospheric ozone depletion potential and its consumption is controlled under the Montreal Protocol and its amendments. We implement a Kalman filter using atmospheric CC14 measurements and a 3-dimensional chemical transport model to estimate the interannual regional industrial emissions and seasonal global oceanic uptake of CCl4 for the period of 1996-2004. The Model of Atmospheric Transport and Chemistry (MATCH), driven by offline National Center for Environmental Prediction (NCEP) reanalysis meteorological fields, is used to simulate CCl4 mole fractions and calculate their sensitivities to regional sources and sinks using a finite difference approach. High frequency observations from the Advanced Global Atmospheric Gases Experiment (AGAGE) and NOAA Earth System Research Laboratory (ESRL) and low frequency flask observations are together used to constrain the source and sink magnitudes, estimated as factors that multiply the a priori fluxes. Although industry data imply that the global industrial emissions were substantially declining with large interannual variations, the optimized results show only small interannual variations and a small decreasing trend. The global surface CCl4 mole fractions were declining in this period because the CCl4 oceanic and stratospheric sinks exceeded the industrial emissions. Compared to the a priori values, the inversion results indicate substantial increases in industrial emissions originating from the South Asian/Indian and Southeast Asian regions, and significant decreases in emissions from the European and North American regions.
NASA Astrophysics Data System (ADS)
Scott, D. K.; Neilsen, T. L.; Weston, C.; Frazier, C.; Smith, T.; Shumway, A.
2015-12-01
Global measurements of vertically-resolved atmospheric wind profiles offer the potential for improved weather forecasts and superior predictions of atmospheric wind patterns. A small-satellite constellation that uses a Fourier Transform Spectrometer (FTS) instrument onboard 12U CubeSats can provide measurements of global tropospheric wind profiles from space at a very low cost. These small satellites are called FTS CubeSats. This presentation will describe a spacecraft concept that provides a stable, robust platform to host the FTS payload. Of importance to the payload are power, data, station keeping, thermal, and accommodations that enable high spectral measurements to be made from a LEO orbit. The spacecraft concept draws on Space Dynamics Laboratory (SDL) heritage and the recent success of the Dynamic Ionosphere Cubesat Experiment (DICE) and HyperAngular Rainbow Polarimeter (HARP) missions. Working with team members, SDL built a prototype observatory (spacecraft and payload) for testing and proof of concept.
Assimilation of SeaWiFS Ocean Chlorophyll Data into a Three-Dimensional Global Ocean Model
NASA Technical Reports Server (NTRS)
Gregg, Watson W.
2005-01-01
Assimilation of satellite ocean color data is a relatively new phenomenon in ocean sciences. However, with routine observations from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), launched in late 1997, and now with new data from the Moderate Resolution Imaging Spectroradometer (MODIS) Aqua, there is increasing interest in ocean color data assimilation. Here SeaWiFS chlorophyll data were assimilated with an established thre-dimentional global ocean model. The assimilation improved estimates of hlorophyll and primary production relative to a free-run (no assimilation) model. This represents the first attempt at ocean color data assimilation using NASA satellites in a global model. The results suggest the potential of assimilation of satellite ocean chlorophyll data for improving models.
NASA Astrophysics Data System (ADS)
Rusomarov, N.; Kochukhov, O.; Piskunov, N.; Jeffers, S. V.; Johns-Krull, C. M.; Keller, C. U.; Makaganiuk, V.; Rodenhuis, M.; Snik, F.; Stempels, H. C.; Valenti, J. A.
2013-10-01
Context. High-resolution spectropolarimetric observations provide simultaneous information about stellar magnetic field topologies and three-dimensional distributions of chemical elements. High-quality spectra in the Stokes IQUV parameters are currently available for very few early-type magnetic chemically peculiar stars. Here we present analysis of a unique full Stokes vector spectropolarimetric data set, acquired for the cool magnetic Ap star HD 24712 with a recently commissioned spectropolarimeter. Aims: The goal of our work is to examine the circular and linear polarization signatures inside spectral lines and to study variation of the stellar spectrum and magnetic observables as a function of rotational phase. Methods: HD 24712 was observed with the HARPSpol instrument at the 3.6-m ESO telescope over a period of 2010-2011. We achieved full rotational phase coverage with 43 individual Stokes parameter observations. The resulting spectra have a signal-to-noise ratio of 300-600 and resolving power exceeding 105. The multiline technique of least-squares deconvolution (LSD) was applied to combine information from the spectral lines of Fe-peak and rare earth elements. Results: We used the HARPSPol spectra of HD 24712 to study the morphology of the Stokes profile shapes in individual spectral lines and in LSD Stokes profiles corresponding to different line masks. From the LSD Stokes V profiles we measured the longitudinal component of the magnetic field, ⟨Bz⟩, with an accuracy of 5-10 G. We also determined the net linear polarization from the LSD Stokes Q and U profiles. Combining previous ⟨Bz⟩ measurements with our data allowed us to determine an improved rotational period of the star, Prot = 12.45812 ± 0.00019 d. We also measured the longitudinal magnetic field from the cores of Hα and Hβ lines. The analysis of ⟨Bz⟩ measurements showed no evidence for a significant radial magnetic field gradient in the atmosphere of HD 24712. We used our ⟨Bz⟩ and
Do, T.; Martinez, G. D.; Bullock, J.; Kaplinghat, M.; Peter, A. H. G.; Yelda, S.; Ghez, A.; Phifer, K.; Lu, J. R.
2013-12-10
We present three-dimensional (3D) kinematic observations of stars within the central 0.5 pc of the Milky Way (MW) nuclear star cluster (NSC) using adaptive optics imaging and spectroscopy from the Keck telescopes. Recent observations have shown that the cluster has a shallower surface density profile than expected for a dynamically relaxed cusp, leading to important implications for its formation and evolution. However, the true 3D profile of the cluster is unknown due to the difficulty in de-projecting the stellar number counts. Here, we use spherical Jeans modeling of individual proper motions and radial velocities to constrain, for the first time, the de-projected spatial density profile, cluster velocity anisotropy, black hole mass (M {sub BH}), and distance to the Galactic center (R {sub 0}) simultaneously. We find that the inner stellar density profile of the late-type stars, ρ(r)∝r {sup –γ}, have a power law slope γ=0.05{sub −0.60}{sup +0.29}, much more shallow than the frequently assumed Bahcall-Wolf slope of γ = 7/4. The measured slope will significantly affect dynamical predictions involving the cluster, such as the dynamical friction time scale. The cluster core must be larger than 0.5 pc, which disfavors some scenarios for its origin. Our measurement of M{sub BH}=5.76{sub −1.26}{sup +1.76}×10{sup 6} M {sub ☉} and R{sub 0}=8.92{sub −0.55}{sup +0.58} kpc is consistent with that derived from stellar orbits within 1'' of Sgr A*. When combined with the orbit of S0-2, the uncertainty on R {sub 0} is reduced by 30% (8.46{sub −0.38}{sup +0.42} kpc). We suggest that the MW NSC can be used in the future in combination with stellar orbits to significantly improve constraints on R {sub 0}.
NASA Technical Reports Server (NTRS)
Strahan, Susan E.; Douglass, Anne R.
2004-01-01
The Global Modeling Initiative (GMI) has integrated two 36-year simulations of an ozone recovery scenario with an offline chemistry and tra nsport model using two different meteorological inputs. Physically ba sed diagnostics, derived from satellite and aircraft data sets, are d escribed and then used to evaluate the realism of temperature and transport processes in the simulations. Processes evaluated include barri er formation in the subtropics and polar regions, and extratropical w ave-driven transport. Some diagnostics are especially relevant to sim ulation of lower stratospheric ozone, but most are applicable to any stratospheric simulation. The global temperature evaluation, which is relevant to gas phase chemical reactions, showed that both sets of me teorological fields have near climatological values at all latitudes and seasons at 30 hPa and below. Both simulations showed weakness in upper stratospheric wave driving. The simulation using input from a g eneral circulation model (GMI(GCM)) showed a very good residual circulation in the tropics and Northern Hemisphere. The simulation with inp ut from a data assimilation system (GMI(DAS)) performed better in the midlatitudes than it did at high latitudes. Neither simulation forms a realistic barrier at the vortex edge, leading to uncertainty in the fate of ozone-depleted vortex air. Overall, tracer transport in the offline GML(GCM) has greater fidelity throughout the stratosphere tha n it does in the GMI(DAS)
Easter, R.C.; Saylor, R.D.; Chapman, E.G.
1993-12-01
The GChM atmospheric chemistry and transport model has been used to analyze the mid-tropospheric CO dataset obtained from NASA`s Measurement of Air Pollution by Satellites (MAPS) program. Fourteen simulations with a 3.75 horizontal resolution have been performed, including a base case and 13 sensitivity runs. The model reproduces many, but not all, of the major features of the MAPS dataset. Locations of peak CO mixing ratios associated with biomass burning as observed in the MAPS experiment are slightly farther south than the model result, indicating either greater horizontal transport than present in the model representation or a spatial difference between the location of modeled biomass fires and actual fires. The current version of GChM was shown to be relatively insensitive to the magnitude of the prescribed NO{sub x} and O{sub 3} global distributions and very insensitive to the depth of the mixed layer as parameterized in the model. Cloud convective transport was shown to play an important role in venting boundary layer CO to the free troposphere. This result agrees with prior meteorological analyses of the MAPS dataset that have-indirectly inferred the presence of convective activity through satellite-based information. Work is continuing to analyze the results of these simulations further and to perform more detailed comparisons between model results and MAPS data.
NASA Astrophysics Data System (ADS)
Kovács, Tamás; Feng, Wuhu; Totterdill, Anna; Plane, John M. C.; Dhomse, Sandip; Gómez-Martín, Juan Carlos; Stiller, Gabriele P.; Haenel, Florian J.; Smith, Christopher; Forster, Piers M.; García, Rolando R.; Marsh, Daniel R.; Chipperfield, Martyn P.
2017-01-01
We have used the Whole Atmosphere Community Climate Model (WACCM), with an updated treatment of loss processes, to determine the atmospheric lifetime of sulfur hexafluoride (SF6). The model includes the following SF6 removal processes: photolysis, electron attachment and reaction with mesospheric metal atoms. The Sodankylä Ion Chemistry (SIC) model is incorporated into the standard version of WACCM to produce a new version with a detailed D region ion chemistry with cluster ions and negative ions. This is used to determine a latitude- and altitude-dependent scaling factor for the electron density in the standard WACCM in order to carry out multi-year SF6 simulations. The model gives a mean SF6 lifetime over an 11-year solar cycle (τ) of 1278 years (with a range from 1120 to 1475 years), which is much shorter than the currently widely used value of 3200 years, due to the larger contribution (97.4 %) of the modelled electron density to the total atmospheric loss. The loss of SF6 by reaction with mesospheric metal atoms (Na and K) is far too slow to affect the lifetime. We investigate how this shorter atmospheric lifetime impacts the use of SF6 to derive stratospheric age of air. The age of air derived from this shorter lifetime SF6 tracer is longer by 9 % in polar latitudes at 20 km compared to a passive SF6 tracer. We also present laboratory measurements of the infrared spectrum of SF6 and find good agreement with previous studies. We calculate the resulting radiative forcings and efficiencies to be, on average, very similar to those reported previously. Our values for the 20-, 100- and 500-year global warming potentials are 18 000, 23 800 and 31 300, respectively.
NASA Technical Reports Server (NTRS)
Cai, DongSheng; Tao, Weinfeng; Yan, Xiaoyang; Lembege, Bertrand; Nishikawa, Ken-Ichi
2007-01-01
Using a three-dimensional full electromagnetic particle model (EMPM), we have performed global simulations of the interaction between the solar wind and the terrestrial magnetosphere, and have investigated its asymptotic stability. The distance between the dayside magnetopause subsolar point and the Earth center, R(sub mp) is measured, as the intensity of southward IMF |B(sub z)| is slowly varying. Based on the field topology theory, one analyzes the variation of R(sub mp) as a reference index of the dynamics of this interaction, when IMF |B(sub z)| successively increases and decreases to its original value. Two striking results are observed. First, as the IMF |B(sub z)| increases above a critical value, the variation of R(sub mp) suddenly changes (so called 'bifurcation' process in field topology). Above this critical value, the overall magnetic field topology changes drastically and is identified as being the signature of magnetic reconnection at the subsolar point on the magnetopause. Second, this subsolar point recovers its original location R(sub mp) by following different paths as the IMF |B(sub z)| value increases (from zero to a maximum fixed value) and decreases (from this maximum to zero) passing through some critical values. These different paths are the signature of 'hysteresis' effect, and are characteristic of the so-called 'subcritical-type' bifurcation. This hysteresis signature indicates that dissipation processes take place via an energy transfer from the solar wind to the magnetosphere by some irreversible way, which leads to a drastic change in the magnetospheric field topology. This hysteresis is interpreted herein as a consequence of the magnetic reconnection taking place at the dayside magnetopause. The field topology reveals to be a very powerful tool to analyze the signatures of three-dimensional magnetic reconnection without the obligation for determining the mechanisms responsible for, and the consequences of the reconnection on the
NASA Technical Reports Server (NTRS)
Taylor, John A.; Brasseur, G. P.; Zimmerman, P. R.; Cicerone, R. J.
1991-01-01
Sources and sinks of methane and methyl chloroform are investigated using a global three-dimensional Lagrangian tropospheric tracer transport model with parameterized hydroxyl and temperature fields. Using the hydroxyl radical field calibrated to the methyl chloroform observations, the globally averaged release of methane and its spatial and temporal distribution were investigated. Two source function models of the spatial and temporal distribution of the flux of methane to the atmosphere were developed. The first model was based on the assumption that methane is emitted as a proportion of net primary productivity (NPP). The second model identified source regions for methane from rice paddies, wetlands, enteric fermentation, termites, and biomass burning based on high-resolution land use data. The most significant difference between the two models were predictions of methane fluxes over China and South East Asia, the location of most of the world's rice paddies, indicating that either the assumption that a uniform fraction of NPP is converted to methane is not valid for rice paddies, or that NPP is underestimated for rice paddies, or that present methane emission estimates from rice paddies are too high.
NASA Astrophysics Data System (ADS)
Takenaka, H.; Komatsu, M.; Toyokuni, G.; Nakamura, T.; Okamoto, T.
2015-12-01
A simple and efficient finite-difference scheme is developed to compute seismic wave propagation for a partial spherical shell model of a three-dimensionally (3-D) heterogeneous global earth structure. This new scheme solves the elastodynamic equations in the "quasi-Cartesian" coordinate system similar to a local Cartesian one, instead of the spherical coordinate system, with a staggered-grid finite-difference method in time domain (FDTD) which is one of the most popular numerical methods in seismic motion simulations for local to regional scale models. The proposed scheme may be useful for modeling seismic wave propagation in a very large region of sub-global scale beyond regional and less than global ones, where the effects of roundness of earth cannot be ignored. In "quasi-Cartesian" coordinates, x, y, and z are set to be locally in directions of latitude, longitude and depth, respectively. The stencil for each of the x-derivatives then depends on the depth coordinate at the evaluation point, while the stencil for each of the y-derivatives varies with both coordinates of the depth and latitude. In order to reduce lateral variations of the horizontal finite-difference stencils over the computational domain, we move the target area to a location around the equator of the computational spherical coordinate system using a way similar to the conversion from equatorial coordinates to ecliptic coordinates. The developed scheme can be easily implemented in 3-D Cartesian FDTD codes for local to regional scale modeling by changing a very small part of the codes. Our scheme may be able to open a window for multi-scale modeling of seismic wave propagation in scales from sub-global to local one.
Three-dimensional metamaterials
Burckel, David Bruce
2012-06-12
A fabrication method is capable of creating canonical metamaterial structures arrayed in a three-dimensional geometry. The method uses a membrane suspended over a cavity with predefined pattern as a directional evaporation mask. Metallic and/or dielectric material can be evaporated at high vacuum through the patterned membrane to deposit resonator structures on the interior walls of the cavity, thereby providing a unit cell of micron-scale dimension. The method can produce volumetric metamaterial structures comprising layers of such unit cells of resonator structures.
Three dimensional quantum chromodynamics
NASA Astrophysics Data System (ADS)
Ferretti, G.; Rajeev, S. G.; Yang, Z.
1992-02-01
The subject of this talk is the study of the low energy behavior of three (2+1) dimensional Quantum Chromodynamics. We show the existence of a phase where parity is unbroken and the flavor group U(2n) is broken into a subgroup U(n)×U(n). We derive the low energy effective action for the theory and show that it has solitonic excitations with Fermi statistic, to be identified with the three dimensional ``baryon''. Finally, we study the current algebra for this effective action and we find a co-homologically nontrivial generalization of Kac-Moody algebras to three dimension.
Three Dimensional Dirac Semimetals
NASA Astrophysics Data System (ADS)
Zaheer, Saad
2014-03-01
Dirac points on the Fermi surface of two dimensional graphene are responsible for its unique electronic behavior. One can ask whether any three dimensional materials support similar pseudorelativistic physics in their bulk electronic spectra. This possibility has been investigated theoretically and is now supported by two successful experimental demonstrations reported during the last year. In this talk, I will summarize the various ways in which Dirac semimetals can be realized in three dimensions with primary focus on a specific theory developed on the basis of representations of crystal spacegroups. A three dimensional Dirac (Weyl) semimetal can appear in the presence (absence) of inversion symmetry by tuning parameters to the phase boundary separating a bulk insulating and a topological insulating phase. More generally, we find that specific rules governing crystal symmetry representations of electrons with spin lead to robust Dirac points at high symmetry points in the Brillouin zone. Combining these rules with microscopic considerations identifies six candidate Dirac semimetals. Another method towards engineering Dirac semimetals involves combining crystal symmetry and band inversion. Several candidate materials have been proposed utilizing this mechanism and one of the candidates has been successfully demonstrated as a Dirac semimetal in two independent experiments. Work carried out in collaboration with: Julia A. Steinberg, Steve M. Young, J.C.Y. Teo, C.L. Kane, E.J. Mele and Andrew M. Rappe.
Three dimensional interactive display
NASA Technical Reports Server (NTRS)
Vranish, John M. (Inventor)
2005-01-01
A three-dimensional (3-D) interactive display and method of forming the same, includes a transparent capaciflector (TC) camera formed on a transparent shield layer on the screen surface. A first dielectric layer is formed on the shield layer. A first wire layer is formed on the first dielectric layer. A second dielectric layer is formed on the first wire layer. A second wire layer is formed on the second dielectric layer. Wires on the first wire layer and second wire layer are grouped into groups of parallel wires with a turnaround at one end of each group and a sensor pad at the opposite end. An operational amplifier is connected to each of the sensor pads and the shield pad biases the pads and receives a signal from connected sensor pads in response to intrusion of a probe. The signal is proportional to probe location with respect to the monitor screen.
Three-Dimensional Complex Variables
NASA Technical Reports Server (NTRS)
Martin, E. Dale
1988-01-01
Report presents new theory of analytic functions of three-dimensional complex variables. While three-dimensional system subject to more limitations and more difficult to use than the two-dimensional system, useful in analysis of three-dimensional fluid flows, electrostatic potentials, and other phenomena involving harmonic functions.
Three dimensional Dirac semimetals
NASA Astrophysics Data System (ADS)
Zaheer, Saad
We extend the physics of graphene to three dimensional systems by showing that Dirac points can exist on the Fermi surface of realistic materials in three dimensions. Many of the exotic electronic properties of graphene can be ascribed to the pseudorelativistic behavior of its charge carriers due to two dimensional Dirac points on the Fermi surface. We show that certain nonsymmorphic spacegroups exhibit Dirac points among the irreducible representations of the appropriate little group at high symmetry points on the surface of the Brillouin zone. We provide a list of all Brillouin zone momenta in the 230 spacegroups that can host Dirac points. We describe microscopic considerations necessary to design materials in one of the candidate spacegroups such that the Dirac point appears at the Fermi energy without any additional non-Dirac-like Fermi pockets. We use density functional theory based methods to propose six new Dirac semimetals: BiO 2 and SbO2 in the beta-cristobalite lattice (spacegroup 227), and BiCaSiO4, BiMgSiO4, BiAlInO 4, and BiZnSiO4 in the distorted spinels lattice (spacegroup 74). Additionally we derive effective Dirac Hamiltonians given group representative operators as well as tight binding models incorporating spin-orbit coupling. Finally we study the Fermi surface of zincblende (spacegroup 216) HgTe which is effectively point-like at Gamma in the Brillouin zone and exhibits accidental degeneracies along a threefold rotation axis. Whereas compressive strain gaps the band structure into a topological insulator, tensile strain shifts the accidental degeneracies away from Gamma and enlarges the Fermi surface. States on the Fermi surface exhibit nontrivial spin texture marked by winding of spins around the threefold rotation axis and by spin vortices indicating a change in the winding number. This is confirmed by microscopic calculations performed in tensile strained HgTe and Hg0.5Zn 0.5 Te as well as k.p theory. We conclude with a summary of recent
Three-dimensional echocardiographic technology.
Salgo, Ivan S
2007-05-01
This article addresses the current state of the art of technology in three-dimensional echocardiography as it applies to transducer design, beam forming, display, and quantification. Because three-dimensional echocardiography encompasses many technical and clinical areas, this article reviews its strengths and limitations and concludes with an analysis of what to use when.
Three-dimensional separation and reattachment
NASA Technical Reports Server (NTRS)
Peake, D. J.; Tobak, M.
1982-01-01
The separation of three dimensional turbulent boundary layers from the lee of flight vehicles at high angles of attack is investigated. The separation results in dominant, large scale, coiled vortex motions that pass along the body in the general direction of the free stream. In all cases of three dimensional flow separation and reattachment, the assumption of continuous vector fields of skin friction lines and external flow streamlines, coupled with simple laws of topology, provides a flow grammar whose elemental constituents are the singular points: the nodes, spiral nodes (foci), and saddles. The phenomenon of three dimensional separation may be construed as either a local or a global event, depending on whether the skin friction line that becomes a line of separation originates at a node or a saddle point.
Topology of three-dimensional separated flows
NASA Technical Reports Server (NTRS)
Tobak, M.; Peake, D. J.
1981-01-01
Based on the hypothesis that patterns of skin-friction lines and external streamlines reflect the properties of continuous vector fields, topology rules define a small number of singular points (nodes, saddle points, and foci) that characterize the patterns on the surface and on particular projections of the flow (e.g., the crossflow plane). The restricted number of singular points and the rules that they obey are considered as an organizing principle whose finite number of elements can be combined in various ways to connect together the properties common to all steady three dimensional viscous flows. Introduction of a distinction between local and global properties of the flow resolves an ambiguity in the proper definition of a three dimensional separated flow. Adoption of the notions of topological structure, structural stability, and bifurcation provides a framework to describe how three dimensional separated flows originate and succeed each other as the relevant parameters of the problem are varied.
Three-dimensional separation and reattachment
NASA Technical Reports Server (NTRS)
Peake, D. J.; Tobak, M.
1982-01-01
The separation of three dimensional turbulent boundary layers from the lee of flight vehicles at high angles of attack is investigated. The separation results in dominant, large scale, coiled vortex motions that pass along the body in the general direction of the free stream. In all cases of three dimensional flow separation and reattachment, the assumption of continuous vector fields of skin friction lines and external flow streamlines, coupled with simple laws of topology, provides a flow grammar whose elemental constituents are the singular points: the nodes, spiral nodes (foci), and saddles. The phenomenon of three dimensional separation may be constrained as either a local or a global event, depending on whether the skin friction line that becomes a line of separation originates at a node or a saddle point.
NASA Astrophysics Data System (ADS)
Kim, Chang-Goo; Ostriker, Eve C.; Kim, Woong-Tae
2014-05-01
We use three-dimensional numerical hydrodynamic simulations of the turbulent, multiphase atomic interstellar medium (ISM) to construct and analyze synthetic H I 21 cm emission and absorption lines. Our analysis provides detailed tests of 21 cm observables as physical diagnostics of the atomic ISM. In particular, we construct (1) the "observed" spin temperature, T_{s, obs}(v_ch)≡ T_B(v_ch)/[1-e^{-τ (v_ch)}], and its optical-depth weighted mean T s, obs; (2) the absorption-corrected "observed" column density, N_H,obs∝ ∫ dv_chT_B(v_ch) τ (v_ch)/[1-e^{-τ (v_ch)}]; and (3) the "observed" fraction of cold neutral medium (CNM), f c, obs ≡ Tc /T s, obs for Tc the CNM temperature; we compare each observed parameter with true values obtained from line-of-sight (LOS) averages in the simulation. Within individual velocity channels, T s, obs(v ch) is within a factor 1.5 of the true value up to τ(v ch) ~ 10. As a consequence, N H, obs and T s, obs are, respectively, within 5% and 12% of the true values for 90% and 99% of LOSs. The optically thin approximation significantly underestimates N H for τ > 1. Provided that Tc is constrained, an accurate observational estimate of the CNM mass fraction can be obtained down to 20%. We show that T s, obs cannot be used to distinguish the relative proportions of warm and thermally unstable atomic gas, although the presence of thermally unstable gas can be discerned from 21 cm lines with 200 K <~ T s, obs(v ch) <~ 1000 K. Our mock observations successfully reproduce and explain the observed distribution of the brightness temperature, optical depth, and spin temperature in Roy et al. The threshold column density for CNM seen in observations is also reproduced by our mock observations. We explain this observed threshold behavior in terms of vertical equilibrium in the local Milky Way's ISM disk.
NASA Astrophysics Data System (ADS)
Dobrovolskas, V.; Kučinskas, A.; Bonifacio, P.; Caffau, E.; Ludwig, H.-G.; Steffen, M.; Spite, M.
2015-04-01
Context. Although oxygen is an important tracer of Galactic chemical evolution, measurements of its abundance in the atmospheres of the oldest Galactic stars are still scarce and rather imprecise. This is mainly because only a few spectral lines are available for the abundance diagnostics. At the lowest end of the metallicity scale, oxygen can only be measured in giant stars and in most of cases such measurements rely on a single forbidden [O i] 630 nm line that is very weak and frequently blended with telluric lines. Although molecular OH lines located in the ultraviolet and infrared could also be used for the diagnostics, oxygen abundances obtained from the OH lines and the [O i] 630 nm line are usually discrepant to a level of ~ 0.3-0.4 dex. Aims: We study the influence of convection on the formation of the infrared (IR) OH lines and the forbidden [O i] 630 nm line in the atmospheres of extremely metal-poor (EMP) red giant stars. Our ultimate goal is to clarify whether a realistic treatment of convection with state-of-the-art 3D hydrodynamical model atmospheres may help to bring the oxygen abundances obtained using the two indicators into closer agreement. Methods: We used high-resolution (R = 50 000) and high signal-to-noise ratio (S/N ≈ 200-600) spectra of four EMP red giant stars obtained with the VLT CRIRES spectrograph. For each EMP star, 4-14 IR OH vibrational-rotational lines located in the spectral range of 1514-1548 and 1595-1632 nm were used to determine oxygen abundances by employing standard 1D local thermodynamic equilibrium (LTE) abundance analysis methodology. We then corrected the 1D LTE abundances obtained from each individual OH line for the 3D hydrodynamical effects, which was done by applying 3D-1D LTE abundance corrections that were determined using 3D hydrodynamical CO5BOLD and 1D hydrostatic LHD model atmospheres. Results: We find that the influence of convection on the formation of [O i] 630 nm line in the atmospheres of EMP giants
NASA Astrophysics Data System (ADS)
Prakapavičius, D.; Kučinskas, A.; Dobrovolskas, V.; Klevas, J.; Steffen, M.; Bonifacio, P.; Ludwig, H.-G.; Spite, M.
2017-03-01
Context. Although oxygen is an important tracer of the early Galactic evolution, its abundance trends with metallicity are still relatively poorly known at [Fe/H] ≲ -2.5. This is in part due to a lack of reliable oxygen abundance indicators in the metal-poor stars, and in part due to shortcomings in 1D LTE abundance analyses where different abundance indicators, such as OH lines located in the UV and IR or the forbidden [O I] line at 630 nm, frequently provide inconsistent results. Aims: In this study, we determined the oxygen abundance in the metal-poor halo giant HD 122563 using a 3D hydrodynamical CO5BOLD model atmosphere. Our main goal was to understand whether a 3D LTE analysis can help to improve the reliability of oxygen abundances that are determined from OH UV lines in comparison to those obtained using standard 1D LTE methodology. Methods: The oxygen abundance in HD 122563 was determined using 71 OH UV lines located in the wavelength range between 308-330 nm. The analysis was performed using a high-resolution VLT UVES spectrum with a 1D LTE spectral line synthesis performed using the SYNTHE package and classical ATLAS9 model atmosphere. Subsequently, a 3D hydrodynamical CO5BOLD and 1D hydrostatic LHD model atmospheres were used to compute 3D-1D abundance corrections. For this, the microturbulence velocity used with the 1D LHD model atmosphere was derived from the hydrodynamical CO5BOLD model atmosphere of HD 122563. The obtained abundance corrections were then applied to determine 3D LTE oxygen abundances from each individual OH UV line. Results: As in previous studies, we found trends in the 1D LTE oxygen abundances determined from OH UV lines with line parameters, such as the line excitation potential, χ, and the line equivalent width, W. These trends become significantly less pronounced in 3D LTE. Using OH UV lines, we determined a 3D LTE oxygen abundance in HD 122563 of A(O)3D LTE = 6.23 ± 0.13 ([O/Fe] = 0.07 ± 0.13). This is in fair agreement
NASA Astrophysics Data System (ADS)
Kučinskas, A.; Steffen, M.; Ludwig, H.-G.; Dobrovolskas, V.; Ivanauskas, A.; Klevas, J.; Prakapavičius, D.; Caffau, E.; Bonifacio, P.
2013-01-01
Aims: We investigate the role of convection in the formation of atomic and molecular lines in the atmosphere of a red giant star. For this purpose we study the formation properties of spectral lines that belong to a number of astrophysically important tracer elements, including neutral and singly ionized atoms (Li I, N I, O I, Na I, Mg I, Al I, Si I, Si II, S I, K I, Ca I, Ca II, Ti I, Ti II, Cr I, Cr II, Mn I, Fe I, Fe II, Co I, Ni I, Zn I, Sr II, Ba II, and Eu II), and molecules (CH, CO, C2, NH, CN, and OH). Methods: We focus our investigation on a prototypical red giant located close to the red giant branch (RGB) tip (Teff = 3660 K, log g = 1.0, [M/H] = 0.0). We used two types of model atmospheres, 3D hydrodynamical and classical 1D, calculated with the CO5BOLD and LHD stellar atmosphere codes, respectively. Both codes share the same atmospheric parameters, chemical composition, equation of state, and opacities, which allowed us to make a strictly differential comparison between the line formation properties predicted in 3D and 1D. The influence of convection on the spectral line formation was assessed with the aid of 3D-1D abundance corrections, which measure the difference between the abundances of chemical species derived with the 3D hydrodynamical and 1D classical model atmospheres. Results: We find that convection plays a significant role in the spectral line formation in this particular red giant. The derived 3D-1D abundance corrections rarely exceed ± 0.1 dex when lines of neutral atoms and molecules are considered, which is in line with the previous findings for solar-metallicity red giants located on the lower RGB. The situation is different with lines that belong to ionized atoms, or to neutral atoms with high ionization potential. In both cases, the corrections for high-excitation lines (χ > 8 eV) may amount to Δ3D-1D ~ -0.4 dex. The 3D-1D abundance corrections generally show a significant wavelength dependence; in most cases they are smaller in
NASA Technical Reports Server (NTRS)
Golombek, Amram; Prinn, Ronald G.
1989-01-01
The annual percentage increases in concentrations of the chlorofluorocarbons CFC-113 (an industrial solvent) and CFC-22 (a refrigerant) are the highest among major chlorofluorocarbons in the atmosphere today. The present-day atmospheric lifetimes for these species are computed using a global three-dimensional dynamical-chemical model. The present-day lifetimes of both are long (15.5 years for CFC-22 and 136 or 195 years for CFC-113, depending on assumed O2 absorption cross sections), underscoring the need to decrease their emissions in order to minimize their future role in ozone destruction and greenhouse warming.
NASA Technical Reports Server (NTRS)
Taylor, Brian R.
2012-01-01
A novel, efficient air data calibration method is proposed for aircraft with limited envelopes. This method uses output-error optimization on three-dimensional inertial velocities to estimate calibration and wind parameters. Calibration parameters are based on assumed calibration models for static pressure, angle of attack, and flank angle. Estimated wind parameters are the north, east, and down components. The only assumptions needed for this method are that the inertial velocities and Euler angles are accurate, the calibration models are correct, and that the steady-state component of wind is constant throughout the maneuver. A two-minute maneuver was designed to excite the aircraft over the range of air data calibration parameters and de-correlate the angle-of-attack bias from the vertical component of wind. Simulation of the X-48B (The Boeing Company, Chicago, Illinois) aircraft was used to validate the method, ultimately using data derived from wind-tunnel testing to simulate the un-calibrated air data measurements. Results from the simulation were accurate and robust to turbulence levels comparable to those observed in flight. Future experiments are planned to evaluate the proposed air data calibration in a flight environment.
Three-dimensional marginal separation
NASA Technical Reports Server (NTRS)
Duck, Peter W.
1988-01-01
The three dimensional marginal separation of a boundary layer along a line of symmetry is considered. The key equation governing the displacement function is derived, and found to be a nonlinear integral equation in two space variables. This is solved iteratively using a pseudo-spectral approach, based partly in double Fourier space, and partly in physical space. Qualitatively, the results are similar to previously reported two dimensional results (which are also computed to test the accuracy of the numerical scheme); however quantitatively the three dimensional results are much different.
Three-dimensional stellarator codes
Garabedian, P. R.
2002-01-01
Three-dimensional computer codes have been used to develop quasisymmetric stellarators with modular coils that are promising candidates for a magnetic fusion reactor. The mathematics of plasma confinement raises serious questions about the numerical calculations. Convergence studies have been performed to assess the best configurations. Comparisons with recent data from large stellarator experiments serve to validate the theory. PMID:12140367
Three dimensional colorimetric assay assemblies
Charych, D.; Reichart, A.
2000-06-27
A direct assay is described using novel three-dimensional polymeric assemblies which change from a blue to red color when exposed to an analyte, in one case a flu virus. The assemblies are typically in the form of liposomes which can be maintained in a suspension, and show great intensity in their color changes. Their method of production is also described.
Three dimensional colorimetric assay assemblies
Charych, Deborah; Reichart, Anke
2000-01-01
A direct assay is described using novel three-dimensional polymeric assemblies which change from a blue to red color when exposed to an analyte, in one case a flu virus. The assemblies are typically in the form of liposomes which can be maintained in a suspension, and show great intensity in their color changes. Their method of production is also described.
Creating Three-Dimensional Scenes
ERIC Educational Resources Information Center
Krumpe, Norm
2005-01-01
Persistence of Vision Raytracer (POV-Ray), a free computer program for creating photo-realistic, three-dimensional scenes and a link for Mathematica users interested in generating POV-Ray files from within Mathematica, is discussed. POV-Ray has great potential in secondary mathematics classrooms and helps in strengthening students' visualization…
Three-Dimensional Lissajous Figures.
ERIC Educational Resources Information Center
D'Mura, John M.
1989-01-01
Described is a mechanically driven device for generating three-dimensional harmonic space figures with different frequencies and phase angles on the X, Y, and Z axes. Discussed are apparatus, viewing stereo pairs, equations of motion, and using space figures in classroom. (YP)
Three-dimensional perspective visualization
NASA Technical Reports Server (NTRS)
Hussey, Kevin
1991-01-01
It was demonstrated that image processing computer graphic techniques can provide an effective means of physiographic analysis of remotely sensed regions through the use of three-dimensional perspective rendering. THe methods used to simulate and animate three-dimensional surfaces from two-dimensional imagery and digital elevation models are explained. A brief historic look at JPL's efforts in this field and several examples of animations, illustrating the evolution of these techniques from 1985, are shown. JPL's current research in this area is discussed along with examples of technology transfer and potential commercial application. The software is part of the VICAR (Video Image Communication and Retrieval) image processing system which was developed at the Multimission Image Processing Laboratory of JPL.
Taylor, J.A. National Center for Atmospheric Research, Boulder, CO ); Brasseur, G.P.; Zimmerman, P.R.; Cicerone, R.J. )
1991-02-20
Using the hydroxyl radical field calibrated to the methyl chloroform observations, the globally averaged release of methane and its spatial and temporal distribution were investigated. Two source function models of the spatial and temporal distribution of the flux of methane to the atmosphere were developed. The first model was based on the assumption that methane is emitted as a proportion of net primary productivity (NPP). With the average hydroxyl radical concentration fixed, the methane source term was computed as {approximately}623 Tg CH{sub 4}, giving an atmospheric lifetime for methane {approximately}8.3 years. The second model identified source regions for methane from rice paddies, wetlands, enteric fermentation, termites, and biomass burning based on high-resolution land use data. This methane source distribution resulted in an estimate of the global total methane source of {approximately}611 Tg CH{sub 4}, giving an atmospheric lifetime for methane {approximately}8.5 years. The most significant difference between the two models were predictions of methane fluxes over China and South East Asia, the location of most of the world's rice paddies. Using a recent measurement of the reaction rate of hydroxyl radical and methane leads to estimates of the global total methane source for SF1 of {approximately}524 Tg CH{sub 4} giving an atmospheric lifetime of {approximately}10.0 years and for SF2{approximately}514 Tg CH{sub 4} yielding a lifetime of {approximately}10.2 years.
Quasicrystalline three-dimensional foams
NASA Astrophysics Data System (ADS)
Cox, S. J.; Graner, F.; Mosseri, R.; Sadoc, J.-F.
2017-03-01
We present a numerical study of quasiperiodic foams, in which the bubbles are generated as duals of quasiperiodic Frank–Kasper phases. These foams are investigated as potential candidates to the celebrated Kelvin problem for the partition of three-dimensional space with equal volume bubbles and minimal surface area. Interestingly, one of the computed structures falls close to (but still slightly above) the best known Weaire–Phelan periodic candidate. In addition we find a correlation between the normalized bubble surface area and the root mean squared deviation of the number of faces, giving an additional clue to understanding the main geometrical ingredients driving the Kelvin problem.
A fusion algorithm for building three-dimensional maps
NASA Astrophysics Data System (ADS)
Vokhmintsev, A.; Makovetskii, A.; Kober, V.; Sochenkov, I.; Kuznetsov, V.
2015-09-01
Recently various algorithms for building of three-dimensional maps of indoor environments have been proposed. In this work we use a Kinect camera that captures RGB images along with depth information for building three-dimensional dense maps of indoor environments. Commonly mapping systems consist of three components; that is, first, spatial alignment of consecutive data frames; second, detection of loop-closures, and finally, globally consistent alignment of the data sequence. It is known that three-dimensional point clouds are well suited for frame-to-frame alignment and for three-dimensional dense reconstruction without the use of valuable visual RGB information. A new fusion algorithm combining visual features and depth information for loop-closure detection followed by pose optimization to build global consistent maps is proposed. The performance of the proposed system in real indoor environments is presented and discussed.
Three-dimensional vortex methods
Greengard, C.A.
1984-08-01
Three-dimensional vortex methods for the computation of incompressible fluid flow are presented from a unified point of view. Reformulations of the filament method and of the method of Beale and Majda show them to be very similar algorithms; in both of them, the vorticity is evaluated by a discretization of the spatial derivative of the flow map. The fact that the filament method, the one which is most often used in practice, can be formulated as a version of the Beale and Majda algorithm in a curved coordinate system is used to give a convergence theorem for the filament method. The method of Anderson is also discussed, in which vorticity is evaluated by the exact differentiation of the approximate velocity field. It is shown that, in the inviscid version of this algorithm, each approximate vector of vorticity remains tangent to a material curve moving with the computed flow, with magnitude proportional to the stretching of this vortex line. This remains true even when time discretization is taken into account. It is explained that the expanding core vortex method converges to a system of equations different from the Navier-Stokes equations. Computations with the filament method of the inviscid interaction of two vortex rings are reported, both with single filaments in each ring and with a fully three-dimensional discretization of vorticity. The dependence on parameters is discussed, and convergence of the computed solutions is observed. 36 references, 4 figures.
Geroux, Christopher M.; Deupree, Robert G.
2015-02-10
Three-dimensional hydrodynamic simulations of full amplitude RR Lyrae stars have been computed for several models across the instability strip. The three-dimensional nature of the calculations allows convection to be treated without reference to a phenomenological approach such as the local mixing length theory. Specifically, the time-dependent interaction of large-scale eddies and radial pulsation is controlled by conservation laws, while the effects of smaller convective eddies are simulated by an eddy viscosity model. The light amplitudes for these calculations are quite similar to those of our previous two-dimensional calculations in the middle of the instability strip, but somewhat lower near the red edge, the fundamental blue edge, and for the one first overtone model we computed. The time-dependent interaction between the radial pulsation and the convective energy transport is essentially the same in three dimensions as it is in two dimensions. There are some differences between the light curves of the two- and three-dimensional simulations, particularly during decreasing light. Reasons for the differences, both numerical and physical, are explored.
Three-dimensional evolution of early solar nebula
NASA Technical Reports Server (NTRS)
Boss, Alan P.
1991-01-01
The progress is reported toward the goal of a complete theory of solar nebula formation, with an emphasis on three spatial dimension models of solar nebular formation and evolution. The following subject areas are covered: (1) initial conditions for protostellar collapse; (2) single versus binary star formation; (3) angular momentum transport mechanisms; (4) three dimensional solar nebula models; and (5) implications for planetary formation.
Differential rotation in solar-like stars from global simulations
Guerrero, G.; Kosovichev, A. G.; Smolarkiewicz, P. K.; Mansour, N. N. E-mail: sasha@sun.stanford.edu E-mail: nagi.n.mansour@nasa.gov
2013-12-20
To explore the physics of large-scale flows in solar-like stars, we perform three-dimensional anelastic simulations of rotating convection for global models with stratification resembling the solar interior. The numerical method is based on an implicit large-eddy simulation approach designed to capture effects from non-resolved small scales. We obtain two regimes of differential rotation, with equatorial zonal flows accelerated either in the direction of rotation (solar-like) or in the opposite direction (anti-solar). While the models with the solar-like differential rotation tend to produce multiple cells of meridional circulation, the models with anti-solar differential rotation result in only one or two meridional cells. Our simulations indicate that the rotation and large-scale flow patterns critically depend on the ratio between buoyancy and Coriolis forces. By including a sub-adiabatic layer at the bottom of the domain, corresponding to the stratification of a radiative zone, we reproduce a layer of strong radial shear similar to the solar tachocline. Similarly, enhanced super-adiabaticity at the top results in a near-surface shear layer located mainly at lower latitudes. The models reveal a latitudinal entropy gradient localized at the base of the convection zone and in the stable region, which, however, does not propagate across the convection zone. In consequence, baroclinicity effects remain small, and the rotation isocontours align in cylinders along the rotation axis. Our results confirm the alignment of large convective cells along the rotation axis in the deep convection zone and suggest that such 'banana-cell' pattern can be hidden beneath the supergranulation layer.
Three-dimensional display technologies.
Geng, Jason
2013-01-01
The physical world around us is three-dimensional (3D), yet traditional display devices can show only two-dimensional (2D) flat images that lack depth (i.e., the third dimension) information. This fundamental restriction greatly limits our ability to perceive and to understand the complexity of real-world objects. Nearly 50% of the capability of the human brain is devoted to processing visual information [Human Anatomy & Physiology (Pearson, 2012)]. Flat images and 2D displays do not harness the brain's power effectively. With rapid advances in the electronics, optics, laser, and photonics fields, true 3D display technologies are making their way into the marketplace. 3D movies, 3D TV, 3D mobile devices, and 3D games have increasingly demanded true 3D display with no eyeglasses (autostereoscopic). Therefore, it would be very beneficial to readers of this journal to have a systematic review of state-of-the-art 3D display technologies.
Three-dimensional coil inductor
Bernhardt, Anthony F.; Malba, Vincent
2002-01-01
A three-dimensional coil inductor is disclosed. The inductor includes a substrate; a set of lower electrically conductive traces positioned on the substrate; a core placed over the lower traces; a set of side electrically conductive traces laid on the core and the lower traces; and a set of upper electrically conductive traces attached to the side traces so as to form the inductor. Fabrication of the inductor includes the steps of forming a set of lower traces on a substrate; positioning a core over the lower traces; forming a set of side traces on the core; connecting the side traces to the lower traces; forming a set of upper traces on the core; and connecting the upper traces to the side traces so as to form a coil structure.
Three-dimensional aromatic networks.
Toyota, Shinji; Iwanaga, Tetsuo
2014-01-01
Three-dimensional (3D) networks consisting of aromatic units and linkers are reviewed from various aspects. To understand principles for the construction of such compounds, we generalize the roles of building units, the synthetic approaches, and the classification of networks. As fundamental compounds, cyclophanes with large aromatic units and aromatic macrocycles with linear acetylene linkers are highlighted in terms of transannular interactions between aromatic units, conformational preference, and resolution of chiral derivatives. Polycyclic cage compounds are constructed from building units by linkages via covalent bonds, metal-coordination bonds, or hydrogen bonds. Large cage networks often include a wide range of guest species in their cavity to afford novel inclusion compounds. Topological isomers consisting of two or more macrocycles are formed by cyclization of preorganized species. Some complicated topological networks are constructed by self-assembly of simple building units.
Three-dimensional vortex methods
NASA Astrophysics Data System (ADS)
Greengard, C. A.
1984-08-01
Reformulations of the filament method and of the method of Beale and Majda show them to be very similar algorithms. The method of Anderson in which vorticity is evaluated by the exact differentiation of the approximate velocity field is discussed. It is shown that, in the inviscid version of this algorithm, each approximate vector of vorticity remains tangent to a material curve moving with the computed flow, with magnitude proportional to the stretching of this vortex line. It is explained that the expanding core vortex method converges to a system of equations different from the Navier-Stokes equations. Computations with the filament method of the inviscid interaction of two vortex rings are reported, both with single filaments in each ring and with a fully three-dimensional discretization of vorticity. The dependence on parameters is discussed, and convergence of the computed solutions is observed.
Three dimensional magnetic abacus memory
Zhang, ShiLei; Zhang, JingYan; Baker, Alexander A.; Wang, ShouGuo; Yu, GuangHua; Hesjedal, Thorsten
2014-01-01
Stacking nonvolatile memory cells into a three-dimensional matrix represents a powerful solution for the future of magnetic memory. However, it is technologically challenging to access the data in the storage medium if large numbers of bits are stacked on top of each other. Here we introduce a new type of multilevel, nonvolatile magnetic memory concept, the magnetic abacus. Instead of storing information in individual magnetic layers, thereby having to read out each magnetic layer separately, the magnetic abacus adopts a new encoding scheme. It is inspired by the idea of second quantisation, dealing with the memory state of the entire stack simultaneously. Direct read operations are implemented by measuring the artificially engineered ‘quantised' Hall voltage, each representing a count of the spin-up and spin-down layers in the stack. This new memory system further allows for both flexible scaling of the system and fast communication among cells. The magnetic abacus provides a promising approach for future nonvolatile 3D magnetic random access memory. PMID:25146338
Three-dimensional colloidal lithography.
Nagai, Hironori; Poteet, Austen; Zhang, Xu A; Chang, Chih-Hao
2017-03-24
Light interactions with colloidal particles can generate a variety of complex three-dimensional (3D) intensity patterns, which can be utilized for nanolithography. The study of particle-light interactions can add more types of intensity patterns by manipulating key factors. Here we investigate a novel 3D nanolithography technique using colloidal particles under two-beam coherent illuminations. The fabricated 3D nanostructures are hollow, nested within periodic structures, and possess multiple chamber geometry. The effects of incident angles and particle size on the fabricated nanostructures were examined. The relative phase shift between particle position and interference pattern is identified as another significant parameter influencing the resultant nanostructures. A numerical model has been developed to show the evolution of nanostructure geometry with phase shifts, and experimental studies confirm the simulation results. Through the introduction of single colloidal particles, the fabrication capability of Lloyd's mirror interference can now be extended to fabrication of 3D nanostructure with complex shell geometry. The fabricated hollow nanostructures with grating background could find potential applications in the area of photonics, drug delivery, and nanofluidics.
Three-dimensional laser microvision.
Shimotahira, H; Iizuka, K; Chu, S C; Wah, C; Costen, F; Yoshikuni, Y
2001-04-10
A three-dimensional (3-D) optical imaging system offering high resolution in all three dimensions, requiring minimum manipulation and capable of real-time operation, is presented. The system derives its capabilities from use of the superstructure grating laser source in the implementation of a laser step frequency radar for depth information acquisition. A synthetic aperture radar technique was also used to further enhance its lateral resolution as well as extend the depth of focus. High-speed operation was made possible by a dual computer system consisting of a host and a remote microcomputer supported by a dual-channel Small Computer System Interface parallel data transfer system. The system is capable of operating near real time. The 3-D display of a tunneling diode, a microwave integrated circuit, and a see-through image taken by the system operating near real time are included. The depth resolution is 40 mum; lateral resolution with a synthetic aperture approach is a fraction of a micrometer and that without it is approximately 10 mum.
Three-Dimensional Laser Microvision
NASA Astrophysics Data System (ADS)
Shimotahira, Hiroshi; Iizuka, Keigo; Chu, Sun-Chun; Wah, Christopher; Costen, Furnie; Yoshikuni, Yuzo
2001-04-01
A three-dimensional (3-D) optical imaging system offering high resolution in all three dimensions, requiring minimum manipulation and capable of real-time operation, is presented. The system derives its capabilities from use of the superstructure grating laser source in the implementation of a laser step frequency radar for depth information acquisition. A synthetic aperture radar technique was also used to further enhance its lateral resolution as well as extend the depth of focus. High-speed operation was made possible by a dual computer system consisting of a host and a remote microcomputer supported by a dual-channel Small Computer System Interface parallel data transfer system. The system is capable of operating near real time. The 3-D display of a tunneling diode, a microwave integrated circuit, and a see-through image taken by the system operating near real time are included. The depth resolution is 40 m; lateral resolution with a synthetic aperture approach is a fraction of a micrometer and that without it is approximately 10 m.
Three-dimensional colloidal lithography
NASA Astrophysics Data System (ADS)
Nagai, Hironori; Poteet, Austen; Zhang, Xu A.; Chang, Chih-Hao
2017-03-01
Light interactions with colloidal particles can generate a variety of complex three-dimensional (3D) intensity patterns, which can be utilized for nanolithography. The study of particle–light interactions can add more types of intensity patterns by manipulating key factors. Here we investigate a novel 3D nanolithography technique using colloidal particles under two-beam coherent illuminations. The fabricated 3D nanostructures are hollow, nested within periodic structures, and possess multiple chamber geometry. The effects of incident angles and particle size on the fabricated nanostructures were examined. The relative phase shift between particle position and interference pattern is identified as another significant parameter influencing the resultant nanostructures. A numerical model has been developed to show the evolution of nanostructure geometry with phase shifts, and experimental studies confirm the simulation results. Through the introduction of single colloidal particles, the fabrication capability of Lloyd’s mirror interference can now be extended to fabrication of 3D nanostructure with complex shell geometry. The fabricated hollow nanostructures with grating background could find potential applications in the area of photonics, drug delivery, and nanofluidics.
Three-dimensional display technologies
Geng, Jason
2014-01-01
The physical world around us is three-dimensional (3D), yet traditional display devices can show only two-dimensional (2D) flat images that lack depth (i.e., the third dimension) information. This fundamental restriction greatly limits our ability to perceive and to understand the complexity of real-world objects. Nearly 50% of the capability of the human brain is devoted to processing visual information [Human Anatomy & Physiology (Pearson, 2012)]. Flat images and 2D displays do not harness the brain’s power effectively. With rapid advances in the electronics, optics, laser, and photonics fields, true 3D display technologies are making their way into the marketplace. 3D movies, 3D TV, 3D mobile devices, and 3D games have increasingly demanded true 3D display with no eyeglasses (autostereoscopic). Therefore, it would be very beneficial to readers of this journal to have a systematic review of state-of-the-art 3D display technologies. PMID:25530827
NASA Astrophysics Data System (ADS)
Beeck, B.; Schüssler, M.; Cameron, R. H.; Reiners, A.
2015-09-01
Context. Magnetic fields affect the local structure of the photosphere of stars. They can considerably influence the radiative properties near the optical surface, flow velocities, and the temperature and pressure profiles. This has an impact on observables such as limb darkening and spectral line profiles. Aims: We aim at understanding qualitatively the influence of small magnetic flux concentrations in unipolar plage regions on the centre-to-limb variation of the intensity and its contrast and on the shape of spectral line profiles in cool main-sequence stars. Methods: We analyse the bolometric and continuum intensity and its angular dependence of 24 radiative magnetohydrodynamic simulations of the near-surface layers of main-sequence stars with six different sets of stellar parameters (spectral types F to early M) and four different average magnetic field strengths (including the non-magnetic case). We also calculated disc-integrated profiles of three spectral lines. Results: The small magnetic flux concentrations formed in the magnetic runs of simulations have a considerable impact on the intensity and its centre-to-limb variation. In some cases, the difference in limb darkening between magnetic and non-magnetic runs is larger than the difference between the spectral types. Spectral lines are not only broadened owing to the Zeeman effect, but are also strongly affected by the modified thermodynamical structure and flow patterns. This indirect magnetic impact on the line profiles is often bigger than that of the Zeeman effect. Conclusions: The effects of the magnetic field on the radiation leaving the star can be considerable and is not restricted to spectral line broadening and polarisation by the Zeeman effect. The inhomogeneous structure of the magnetic field on small length scales and its impact on (and spatial correlation with) the local thermodynamical structure and the flow field near the surface influence the measurement of the global field properties
Three dimensional identification card and applications
NASA Astrophysics Data System (ADS)
Zhou, Changhe; Wang, Shaoqing; Li, Chao; Li, Hao; Liu, Zhao
2016-10-01
Three dimensional Identification Card, with its three-dimensional personal image displayed and stored for personal identification, is supposed be the advanced version of the present two-dimensional identification card in the future [1]. Three dimensional Identification Card means that there are three-dimensional optical techniques are used, the personal image on ID card is displayed to be three-dimensional, so we can see three dimensional personal face. The ID card also stores the three-dimensional face information in its inside electronics chip, which might be recorded by using two-channel cameras, and it can be displayed in computer as three-dimensional images for personal identification. Three-dimensional ID card might be one interesting direction to update the present two-dimensional card in the future. Three-dimension ID card might be widely used in airport custom, entrance of hotel, school, university, as passport for on-line banking, registration of on-line game, etc...
Three-dimensional map construction.
Jenks, G F; Brown, D A
1966-11-18
Three-dimensional maps are useful tools which have been neglected for some time. They shouldbe more commonly used, and familiarity with the techniques discussed in this article should dispel any qualms anyone might ve about needing artistic talent to nstruct them. The saving in time esulting from the use of an anamorphoser provides a further incentive. The anamorphoser transformations discussed above were all prepared by using straight slits, oriented at right angles to each other and placed so that all planes of the elements were parallel to each other. It is possible to vary these conditions in an infinite number of ways and thereby produce nonparallel tranceformations. Some of these variations are illustrated in Fig. 10. All the illustrations in Fig. 10 are transformations of the planimetric weather map shown in Fig. 8A. The variations used for the maps of Fig. 10 are as follows. (A) All planes parallel, with a curved rear slit; (B) all planes parallel, with curved slits front and rear; ( C) all planes parallel, with S-shaped rear slit; (D) all planes parallel, with an undulating rear slit; (E) all planes parallel, with curved front and undulating rear slit; (F) plane of the original rotated on the horizontal axis-both slits curved; (G) plane of the original rotated on thevertical axis- both slits curved; (H) plane of the original rotated on the horizontal axis -both slits straight. These are only a few of the many transformations which can be made with an anamorphoser, butthey do point toward some interesting possibilities. For example, it appears that maps based onone projection might be altered to satisfy the coordinates of a completely different projection. Note, for example, the change of parallels from concave to convex curves (Figs. 8A and 10A) and the change from converging meridians to diverging meridians (Figs. 8A and l0G). Similarly, the grids of maps B, F, and H of Fig. 10 approximate projections which are quite different from the original. Other
NASA Astrophysics Data System (ADS)
Edmondson, Justin K.
To understand the evolution of the solar corona and the generation of the solar wind, it is necessary to understand the structure and dynamics of the coronal magnetic field. Phenomenologically-based "quasi-steady" models have been developed under the assumption that the corona evolves as a time series of force-free equilibrium states determined by the normal-flux distribution at the photosphere. These models are successful at predicting the overall field polarity, global magnetic structures, and position of the heliospheric current sheet. However, the quasi-steady models cannot account for the observed bi-modal flow structure of the solar wind, nor several heliospheric observations with implications for the dynamics of the magnetic field. Motivated by these limitations, several researchers have proposed a fundamentally different paradigm for the evolution of the corona, the so-called interchange model. Based on the interchange reconnection (IR) process, this model predicts a structure for the coronal magnetic field which substantially differs from the quasi-steady view. Strictly speaking, IR describes three-dimensional (3D) null point reconnection, in which closed bipolar flux reconnects with coronal hole flux opening into the heliosphere. More generally, the 3D null point reconnection mechanism is a direct consequence of the nested multi-polar field structure which occurs ubiquitously throughout the entire corona. This dissertation aims to rigorously investigate the 3D null point reconnection mechanism and the consequences thereof on the coronal environment. To that end, we present several related simulations that examine current sheet formation and stability, as well as the consequences of this type of reconnection on the structure and dynamics of the global magnetic field. We show the field topology remains smooth during the evolutions, incompatible with predictions of the initially proposed interchange model. In addition, we demonstrate dynamic effects of IR
Three Dimensional Illustrating--Three-Dimensional Vision and Deception of Sensibility
ERIC Educational Resources Information Center
Szállassy, Noémi; Gánóczy, Anita; Kriska, György
2009-01-01
The wide-spread digital photography and computer use gave the opportunity for everyone to make three-dimensional pictures and to make them public. The new opportunities with three-dimensional techniques give chance for the birth of new artistic photographs. We present in detail the biological roots of three-dimensional visualization, the phenomena…
Lattice theory of three-dimensional cracks
NASA Technical Reports Server (NTRS)
Esterling, D. M.
1976-01-01
The problem of the stability of a three-dimensional crack is analyzed within a lattice-statics approximation. The consequence of introducing a jog into the crack face as well as the effects of various nonlinear-force laws are studied. The phenomenon of lattice trapping (upper and lower bounds on the applied stress for an equilibrium crack of given length) is again obtained. It is possible to obtain some physical insight into which aspects of the force law are critical for crack stability. In particular, the inadequacy of a thermodynamic approach - which relates the critical stress to a surface energy corresponding to the area under the cohesive-force-vs-displacement curve - is demonstrated. Surface energy is a global property of the cohesive-force law. Crack stability is sensitive to much more refined aspects of the cohesive-force law. Crack healing is sensitive to the long-range portion of the cohesive force. Crack expansion is sensitive to the position of the maximum in the cohesive-force relation.
Three-dimensional velocity measurements using LDA
NASA Astrophysics Data System (ADS)
Buchhave, Preben
The design requirements for and development of an LDA that measures the three components of the fluid velocity vector are described. The problems encountered in LDA measurements in highly turbulent flows, multivariate response, velocity bias, spatial resolution, temporal resolution, and dynamic range, are discussed. The use of the fringe and/or the reference beam methods to measure the three velocity components, and the use of color, frequency shift, and polarization to separate three velocity projections are examined. Consideration is given to the coordinate transformation, the presentation of three-dimensional LDA data, and the possibility of three-dimensional bias correction. Procedures for conducting three-dimensional LDA measurements are proposed.
Three Dimensional Optic Tissue Culture and Process
NASA Technical Reports Server (NTRS)
OConnor, Kim C. (Inventor); Spaulding, Glenn F. (Inventor); Goodwin, Thomas J. (Inventor); Aten, Laurie A. (Inventor); Francis, Karen M. (Inventor); Caldwell, Delmar R. (Inventor); Prewett, Tacey L. (Inventor); Fitzgerald, Wendy S. (Inventor)
1999-01-01
A process for artificially producing three-dimensional optic tissue has been developed. The optic cells are cultured in a bioireactor at low shear conditions. The tissue forms as normal, functional tissue grows with tissue organization and extracellular matrix formation.
Three dimensional optic tissue culture and process
NASA Technical Reports Server (NTRS)
Spaulding, Glenn F. (Inventor); Prewett, Tacey L. (Inventor); Goodwin, Thomas J. (Inventor); Francis, Karen M. (Inventor); Cardwell, Delmar R. (Inventor); Oconnor, Kim (Inventor); Fitzgerald, Wendy S. (Inventor); Aten, Laurie A. (Inventor)
1994-01-01
A process for artificially producing three-dimensional optic tissue has been developed. The optic cells are cultured in a bioreactor at low shear conditions. The tissue forms normal, functional tissue organization and extracellular matrix.
Three-Dimensional Dynamical Instabilities in Galactic Ionization Fronts
NASA Astrophysics Data System (ADS)
Whalen, Daniel J.; Norman, Michael L.
2008-01-01
Ionization front instabilities have long been of interest for their suspected role in a variety of phenomena in the Galaxy, from the formation of bright rims and "elephant trunks" in nebulae to triggered star formation in molecular clouds. Numerical treatments of these instabilities have historically been limited in both dimensionality and input physics, leaving important questions about their true evolution unanswered. We present the first three-dimensional radiation hydrodynamical calculations of both R-type (rarefied) and D-type (dense) ionization front instabilities in Galactic environments (i.e., solar-metallicity gas). Consistent with linear stability analyses of planar D-type fronts, our models exhibit many short-wavelength perturbations that grow at early times and later evolve into fewer large-wavelength structures. The simulations demonstrate that both self-consistent radiative transfer and three-dimensional flow introduce significant morphological differences to unstable modes when compared to earlier two-dimensional approximate models. We find that the amplitude of the instabilities in the nonlinear regime is primarily determined by the efficiency of cooling within the shocked neutral shell. Strong radiative cooling leads to long, extended structures with pronounced clumping, while weaker cooling leads to saturated modes that devolve into turbulent flows. These results suggest that expanding H II regions may either promote or provide turbulent support against the formation of later generations of stars, with potential consequences for star formation rates in the Galaxy today.
Vision in our three-dimensional world
2016-01-01
Many aspects of our perceptual experience are dominated by the fact that our two eyes point forward. Whilst the location of our eyes leaves the environment behind our head inaccessible to vision, co-ordinated use of our two eyes gives us direct access to the three-dimensional structure of the scene in front of us, through the mechanism of stereoscopic vision. Scientific understanding of the different brain regions involved in stereoscopic vision and three-dimensional spatial cognition is changing rapidly, with consequent influences on fields as diverse as clinical practice in ophthalmology and the technology of virtual reality devices. This article is part of the themed issue ‘Vision in our three-dimensional world’. PMID:27269595
Three-dimensional magnetic bubble memory system
NASA Technical Reports Server (NTRS)
Stadler, Henry L. (Inventor); Katti, Romney R. (Inventor); Wu, Jiin-Chuan (Inventor)
1994-01-01
A compact memory uses magnetic bubble technology for providing data storage. A three-dimensional arrangement, in the form of stacks of magnetic bubble layers, is used to achieve high volumetric storage density. Output tracks are used within each layer to allow data to be accessed uniquely and unambiguously. Storage can be achieved using either current access or field access magnetic bubble technology. Optical sensing via the Faraday effect is used to detect data. Optical sensing facilitates the accessing of data from within the three-dimensional package and lends itself to parallel operation for supporting high data rates and vector and parallel processing.
Three-dimensional displays and stereo vision.
Westheimer, Gerald
2011-08-07
Procedures for three-dimensional image reconstruction that are based on the optical and neural apparatus of human stereoscopic vision have to be designed to work in conjunction with it. The principal methods of implementing stereo displays are described. Properties of the human visual system are outlined as they relate to depth discrimination capabilities and achieving optimal performance in stereo tasks. The concept of depth rendition is introduced to define the change in the parameters of three-dimensional configurations for cases in which the physical disposition of the stereo camera with respect to the viewed object differs from that of the observer's eyes.
Fabrication of three dimensional microstructure fiber
NASA Astrophysics Data System (ADS)
Luo, Ying; Ma, Jie; Chen, Zhe; Lu, Huihui; Zhong, Yongchun
2015-05-01
A method of fabricating three dimensional (3D) microstructured fiber is presented. Polystyrene (PS) microspheres were coated around the surface of a micro-fiber through isothermal heating evaporation induced self-assembly method. Scanning electron microscopy (SEM) image shows that the colloidal crystal has continuous, uniform, and well-ordered face-centered cubic (FCC) structure, with [111] crystallographic direction normal to the surface of micro-fiber. This micro-fiber with three-dimensional photonic crystals structure is very useful in the applications of micro-fiber sensors or filters.
Three-dimensional stochastic vortex flows
NASA Astrophysics Data System (ADS)
Esposito, R.; Pulvirenti, M.
1989-08-01
It is well known that the dynamics of point vortices approximate, under suitable limits, the two-dimensional Euler flow for an ideal fluid. To find particle models for three-dimensional flows is a more intricate problem. A stochastic version of the algorithm introduced by Beale amd Maida (1982) for simulating the behavior of a three-dimensional Euler flow is introduced here, and convergence to the Navier-Stokes (NS) flow in R exp 3 is shown. The result is based on a stochastic Lagrangian picture of the NS equations.
Three-Dimensional Shallow Water Acoustics
2016-03-30
13-1-0026 entitled "Three- Dimensional Shallow Water Acoustics," Principal Investigator Dr. Ying-Tsong Lin. Sincerely, ;l1,J-Ju1 ~{hjM1...30/03/2016 01/01/2013-12/31/2015 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBERS Three-Dimensional Shallow Water Acoustics 5b, GRANT NUMBER N0001 4-13-1... Water Acoustics Dr. Ying-Tsong Lin Applied Ocean Physics and Engineering Department Woods Hole Oceanographic Institution, Woods Hole, MA 02543
Three-dimensional patterning methods and related devices
Putnam, Morgan C.; Kelzenberg, Michael D.; Atwater, Harry A.; Boettcher, Shannon W.; Lewis, Nathan S.; Spurgeon, Joshua M.; Turner-Evans, Daniel B.; Warren, Emily L.
2016-12-27
Three-dimensional patterning methods of a three-dimensional microstructure, such as a semiconductor wire array, are described, in conjunction with etching and/or deposition steps to pattern the three-dimensional microstructure.
Three-Dimensional Visualization of Particle Tracks.
ERIC Educational Resources Information Center
Julian, Glenn M.
1993-01-01
Suggests ways to bring home to the introductory physics student some of the excitement of recent discoveries in particle physics. Describes particle detectors and encourages the use of the Standard Model along with real images of particle tracks to determine three-dimensional views of tracks. (MVL)
Three Dimensional Display Of Meteorological Scientific Data
NASA Astrophysics Data System (ADS)
Grotch, Stanley L.
1988-01-01
Even a cursory reading of any daily newspaper shows that we are in the midst of a dramatic revolution in computer graphics. Virtually every day some new piece of hardware or software is announced, adding to the tools available to the working scientist. Three dimensional graphics form a significant part of this revolution having become virtually commonplace in advertising and on television.
Three-dimensional chiral photonic superlattices.
Thiel, M; Fischer, H; von Freymann, G; Wegener, M
2010-01-15
We investigate three-dimensional photonic superlattices composed of polymeric helices in various spatial checkerboard-like arrangements. Depending on the relative phase shift and handedness of the chiral building blocks, different circular-dichroism resonances appear or are suppressed. Samples corresponding to four different configurations are fabricated by direct laser writing. The measured optical transmittance spectra are in good agreement with numerical calculations.
Three-dimensional colorimetric assay assemblies
Charych, Deborah; Reichert, Anke
2001-01-01
A direct assay is described using novel three-dimensional polymeric assemblies which change from a blue to red color when exposed to an analyte, in one case a flue virus. The assemblies are typically in the form of liposomes which can be maintained in a suspension, and show great intensity in their color changes. Their method of production is also described.
Three-dimensional rf structure calculations
Cooper, R.K.; Browman, M.J.; Weiland, T.
1988-01-01
The calculation of three-dimensional rf structures is rapidly approaching adolescence, after having been in its infancy for the last four years. This paper will show the kinds of calculations that are currently being performed in the frequency domain and is a companion paper to one in which time-domain calculations are described. 13 refs., 14 figs.
Three-dimensional RF structure calculations
NASA Astrophysics Data System (ADS)
Cooper, R. K.; Browman, M. J.; Weiland, T.
1989-04-01
The calculation of three-dimensional rf structures is rapidly approaching adolescence, after having been in its infancy for the last four years. This paper will show the kinds of calculations that are currently being performed in the frequency domain and is a companion paper to one in which time-domain calculations are described.
Three dimensional reconnection in astrophysical plasmas
NASA Technical Reports Server (NTRS)
Spicer, D. S.
1990-01-01
Theoretical issues related to three-dimensional reconnection and its application to the space and astrophysical environment are reviewed. Consideration is given to the meaning of reconnection in three dimensions, the way in which periodic and nonperiodic magnetic topologies alter the physics of reconnections, and the effects of chaotic magnetic fields on the reconnection process.
[Three Dimensional Display in Nuclear Medicine].
Teraoka, Satomi; Souma, Tsutomu
2015-01-01
Imaging techniques to obtain a tomographic image in nuclear medicine such as PET and SPECT are widely used. It is necessary to interpreting all of the tomographic images obtained in order to accurately evaluate the individual lesion, whereas three dimensional display is often useful in order to overview and evaluate the feature of the entire lesion or disease such as the position, size and abnormal pattern. In Japan, the use of three dimensional image analysis workstation with an application of the co-registration and image fusion between the functional images such as PET or SPECT and anatomical images such as CT or MRI has been generalized. In addition, multimodality imaging system such as a PET/CT and SPECT/CT has been widespread. Therefore, it is expected to improve the diagnostic accuracy using three dimensionally image fusion to functional images with poor anatomical information. In this commentary, as an example of a three dimensional display that are commonly used in nuclear medicine examination in Japan, brain regions, cardiac region and bone and tumor region will be introduced separately.
Growing Three-Dimensional Cocultures Of Cells
NASA Technical Reports Server (NTRS)
Wolf, David A.; Goodwin, Thomas J.
1995-01-01
Laboratory process provides environmental conditions favoring simultaneous growth of cocultures of mammalian cells of more than one type. Cultures become three-dimensional tissuelike assemblies serving as organoid models of differentiation of cells. Process used, for example, to study growth of human colon cancers, starting from mixtures of normal colonic fibroblasts and partially differentiated colon adenocarcinoma cells.
Three-Dimensional Pointers for Stereoscopic Projection.
ERIC Educational Resources Information Center
Hayman, H. J. G.
1984-01-01
Because class size often limits student opportunity to handle individual models, teachers use stereoscopic projections to demonstrate structural features. Describes three-dimensional pointers for use with different projection systems so teachers can indicate a particular atom or bond to entire classes, avoiding the perspective problems inherent in…
Three-Dimensional Printing Surgical Applications
Griffin, Michelle F.; Butler, Peter E.
2015-01-01
Introduction: Three-dimensional printing, a technology used for decades in the industrial field, gains a lot of attention in the medical field for its potential benefits. With advancement of desktop printers, this technology is accessible and a lot of research is going on in the medical field. Objective: To evaluate its application in surgical field, which may include but not limited to surgical planning, surgical education, implants, and prosthesis, which are the focus of this review. Methods: Research was conducted by searching PubMed, Web of science, and other reliable sources. We included original articles and excluded articles based on animals, those more than 10 years old, and those not in English. These articles were evaluated, and relevant studies were included in this review. Discussion: Three-dimensional printing shows a potential benefit in surgical application. Printed implants were used in patient in a few cases and show successful results; however, longer follow-up and more trials are needed. Surgical and medical education is believed to be more efficient with this technology than the current practice. Printed surgical instrument and surgical planning are also believed to improve with three-dimensional printing. Conclusion: Three-dimensional printing can be a very powerful tool in the near future, which can aid the medical field that is facing a lot of challenges and obstacles. However, despite the reported results, further research on larger samples and analytical measurements should be conducted to ensure this technology's impact on the practice. PMID:26301002
Three-dimensional implicit lambda methods
NASA Technical Reports Server (NTRS)
Napolitano, M.; Dadone, A.
1983-01-01
This paper derives the three dimensional lambda-formulation equations for a general orthogonal curvilinear coordinate system and provides various block-explicit and block-implicit methods for solving them, numerically. Three model problems, characterized by subsonic, supersonic and transonic flow conditions, are used to assess the reliability and compare the efficiency of the proposed methods.
Optical Alignment of the Global Precipitation Measurement (GPM) Star Trackers
NASA Technical Reports Server (NTRS)
Hetherington, Samuel; Osgood, Dean; McMann, Joe; Roberts, Viki; Gill, James; Mclean, Kyle
2013-01-01
The optical alignment of the star trackers on the Global Precipitation Measurement (GPM) core spacecraft at NASA Goddard Space Flight Center (GSFC) was challenging due to the layout and structural design of the GPM Lower Bus Structure (LBS) in which the star trackers are mounted as well as the presence of the star tracker shades that blocked line-of-sight to the primary star tracker optical references. The initial solution was to negotiate minor changes in the original LBS design to allow for the installation of a removable item of ground support equipment (GSE) that could be installed whenever measurements of the star tracker optical references were needed. However, this GSE could only be used to measure secondary optical reference cube faces not used by the star tracker vendor to obtain the relationship information and matrix transformations necessary to determine star tracker alignment. Unfortunately, due to unexpectedly large orthogonality errors between the measured secondary adjacent cube faces and the lack of cube calibration data, we required a method that could be used to measure the same reference cube faces as originally measured by the vendor. We describe an alternative technique to theodolite auto-collimation for measurement of an optical reference mirror pointing direction when normal incidence measurements are not possible. This technique was used to successfully align the GPM star trackers and has been used on a number of other NASA flight projects. We also discuss alignment theory as well as a GSFC-developed theodolite data analysis package used to analyze angular metrology data.
Global diversity of brittle stars (Echinodermata: Ophiuroidea).
Stöhr, Sabine; O'Hara, Timothy D; Thuy, Ben
2012-01-01
This review presents a comprehensive overview of the current status regarding the global diversity of the echinoderm class Ophiuroidea, focussing on taxonomy and distribution patterns, with brief introduction to their anatomy, biology, phylogeny, and palaeontological history. A glossary of terms is provided. Species names and taxonomic decisions have been extracted from the literature and compiled in The World Ophiuroidea Database, part of the World Register of Marine Species (WoRMS). Ophiuroidea, with 2064 known species, are the largest class of Echinodermata. A table presents 16 families with numbers of genera and species. The largest are Amphiuridae (467), Ophiuridae (344 species) and Ophiacanthidae (319 species). A biogeographic analysis for all world oceans and all accepted species was performed, based on published distribution records. Approximately similar numbers of species were recorded from the shelf (n = 1313) and bathyal depth strata (1297). The Indo-Pacific region had the highest species richness overall (825 species) and at all depths. Adjacent regions were also relatively species rich, including the North Pacific (398), South Pacific (355) and Indian (316) due to the presence of many Indo-Pacific species that partially extended into these regions. A secondary region of enhanced species richness was found in the West Atlantic (335). Regions of relatively low species richness include the Arctic (73 species), East Atlantic (118), South America (124) and Antarctic (126).
Global Diversity of Brittle Stars (Echinodermata: Ophiuroidea)
Stöhr, Sabine; O'Hara, Timothy D.; Thuy, Ben
2012-01-01
This review presents a comprehensive overview of the current status regarding the global diversity of the echinoderm class Ophiuroidea, focussing on taxonomy and distribution patterns, with brief introduction to their anatomy, biology, phylogeny, and palaeontological history. A glossary of terms is provided. Species names and taxonomic decisions have been extracted from the literature and compiled in The World Ophiuroidea Database, part of the World Register of Marine Species (WoRMS). Ophiuroidea, with 2064 known species, are the largest class of Echinodermata. A table presents 16 families with numbers of genera and species. The largest are Amphiuridae (467), Ophiuridae (344 species) and Ophiacanthidae (319 species). A biogeographic analysis for all world oceans and all accepted species was performed, based on published distribution records. Approximately similar numbers of species were recorded from the shelf (n = 1313) and bathyal depth strata (1297). The Indo-Pacific region had the highest species richness overall (825 species) and at all depths. Adjacent regions were also relatively species rich, including the North Pacific (398), South Pacific (355) and Indian (316) due to the presence of many Indo-Pacific species that partially extended into these regions. A secondary region of enhanced species richness was found in the West Atlantic (335). Regions of relatively low species richness include the Arctic (73 species), East Atlantic (118), South America (124) and Antarctic (126). PMID:22396744
Three-dimensional bio-printing.
Gu, Qi; Hao, Jie; Lu, YangJie; Wang, Liu; Wallace, Gordon G; Zhou, Qi
2015-05-01
Three-dimensional (3D) printing technology has been widely used in various manufacturing operations including automotive, defence and space industries. 3D printing has the advantages of personalization, flexibility and high resolution, and is therefore becoming increasingly visible in the high-tech fields. Three-dimensional bio-printing technology also holds promise for future use in medical applications. At present 3D bio-printing is mainly used for simulating and reconstructing some hard tissues or for preparing drug-delivery systems in the medical area. The fabrication of 3D structures with living cells and bioactive moieties spatially distributed throughout will be realisable. Fabrication of complex tissues and organs is still at the exploratory stage. This review summarize the development of 3D bio-printing and its potential in medical applications, as well as discussing the current challenges faced by 3D bio-printing.
Real time three dimensional sensing system
Gordon, Steven J.
1996-01-01
The invention is a three dimensional sensing system which utilizes two flexibly located cameras for receiving and recording visual information with respect to a sensed object illuminated by a series of light planes. Each pixel of each image is converted to a digital word and the words are grouped into stripes, each stripe comprising contiguous pixels. One pixel of each stripe in one image is selected and an epi-polar line of that point is drawn in the other image. The three dimensional coordinate of each selected point is determined by determining the point on said epi-polar line which also lies on a stripe in the second image and which is closest to a known light plane.
Real time three dimensional sensing system
Gordon, S.J.
1996-12-31
The invention is a three dimensional sensing system which utilizes two flexibly located cameras for receiving and recording visual information with respect to a sensed object illuminated by a series of light planes. Each pixel of each image is converted to a digital word and the words are grouped into stripes, each stripe comprising contiguous pixels. One pixel of each stripe in one image is selected and an epi-polar line of that point is drawn in the other image. The three dimensional coordinate of each selected point is determined by determining the point on said epi-polar line which also lies on a stripe in the second image and which is closest to a known light plane. 7 figs.
Three-dimensional imaging modalities in endodontics
Mao, Teresa
2014-01-01
Recent research in endodontics has highlighted the need for three-dimensional imaging in the clinical arena as well as in research. Three-dimensional imaging using computed tomography (CT) has been used in endodontics over the past decade. Three types of CT scans have been studied in endodontics, namely cone-beam CT, spiral CT, and peripheral quantitative CT. Contemporary endodontics places an emphasis on the use of cone-beam CT for an accurate diagnosis of parameters that cannot be visualized on a two-dimensional image. This review discusses the role of CT in endodontics, pertaining to its importance in the diagnosis of root canal anatomy, detection of peri-radicular lesions, diagnosis of trauma and resorption, presurgical assessment, and evaluation of the treatment outcome. PMID:25279337
Bootstrapping the Three Dimensional Supersymmetric Ising Model.
Bobev, Nikolay; El-Showk, Sheer; Mazáč, Dalimil; Paulos, Miguel F
2015-07-31
We implement the conformal bootstrap program for three dimensional conformal field theories with N=2 supersymmetry and find universal constraints on the spectrum of operator dimensions in these theories. By studying the bounds on the dimension of the first scalar appearing in the operator product expansion of a chiral and an antichiral primary, we find a kink at the expected location of the critical three dimensional N=2 Wess-Zumino model, which can be thought of as a supersymmetric analog of the critical Ising model. Focusing on this kink, we determine, to high accuracy, the low-lying spectrum of operator dimensions of the theory, as well as the stress-tensor two-point function. We find that the latter is in an excellent agreement with an exact computation.
Three-dimensional effects on airfoils
NASA Technical Reports Server (NTRS)
Chevallier, J. P.
1983-01-01
The effects of boundary layer flows along the walls of wind tunnels were studied to validate the transfer of two dimensional calculations to three dimensional transonic flowfield calculations. Results from trials in various wind tunnels were examind to determine the effects of the wall boundary flow on the control surfaces of an airfoil. Models sliding along a groove in the wall of a channel at sub- and transonic speeds were examined, with the finding that with either nonuniformities in the groove, or even if the channel walls are uniform, the lateral boundary layer can cause variations in the central flow region or alter the onset of shock at the transition point. Models for the effects in both turbulence and in the absence of turbulence are formulated, and it is noted that the characteristics of individual wind tunnels must be studied to quantify any existing three dimensional effects.
Three dimensional fabrication at small size scales
Leong, Timothy G.; Zarafshar, Aasiyeh M.; Gracias, David H.
2010-01-01
Despite the fact that we live in a three-dimensional (3D) world and macroscale engineering is 3D, conventional sub-mm scale engineering is inherently two-dimensional (2D). New fabrication and patterning strategies are needed to enable truly three-dimensionally-engineered structures at small size scales. Here, we review strategies that have been developed over the last two decades that seek to enable such millimeter to nanoscale 3D fabrication and patterning. A focus of this review is the strategy of self-assembly, specifically in a biologically inspired, more deterministic form known as self-folding. Self-folding methods can leverage the strengths of lithography to enable the construction of precisely patterned 3D structures and “smart” components. This self-assembling approach is compared with other 3D fabrication paradigms, and its advantages and disadvantages are discussed. PMID:20349446
Three-dimensional imaging modalities in endodontics.
Mao, Teresa; Neelakantan, Prasanna
2014-09-01
Recent research in endodontics has highlighted the need for three-dimensional imaging in the clinical arena as well as in research. Three-dimensional imaging using computed tomography (CT) has been used in endodontics over the past decade. Three types of CT scans have been studied in endodontics, namely cone-beam CT, spiral CT, and peripheral quantitative CT. Contemporary endodontics places an emphasis on the use of cone-beam CT for an accurate diagnosis of parameters that cannot be visualized on a two-dimensional image. This review discusses the role of CT in endodontics, pertaining to its importance in the diagnosis of root canal anatomy, detection of peri-radicular lesions, diagnosis of trauma and resorption, presurgical assessment, and evaluation of the treatment outcome.
Three-dimensional metallic boron nitride.
Zhang, Shunhong; Wang, Qian; Kawazoe, Yoshiyuki; Jena, Puru
2013-12-04
Boron nitride (BN) and carbon are chemical analogues of each other and share similar structures such as one-dimensional nanotubes, two-dimensional nanosheets characterized by sp(2) bonding, and three-dimensional diamond structures characterized by sp(3) bonding. However, unlike carbon which can be metallic in one, two, and three dimensions, BN is an insulator, irrespective of its structure and dimensionality. On the basis of state-of-the-art theoretical calculations, we propose a tetragonal phase of BN which is both dynamically stable and metallic. Analysis of its band structure, density of states, and electron localization function confirms the origin of the metallic behavior to be due to the delocalized B 2p electrons. The metallicity exhibited in the studied three-dimensional BN structures can lead to materials beyond conventional ceramics as well as to materials with potential for applications in electronic devices.
Analysis of three-dimensional transonic compressors
NASA Technical Reports Server (NTRS)
Bourgeade, A.
1984-01-01
A method for computing the three-dimensional transonic flow around the blades of a compressor or of a propeller is given. The method is based on the use of the velocity potential, on the hypothesis that the flow is inviscid, irrotational and isentropic. The equation of the potential is solved in a transformed space such that the surface of the blade is mapped into a plane where the periodicity is implicit. This equation is in a nonconservative form and is solved with the help of a finite difference method using artificial time. A computer code is provided and some sample results are given in order to demonstrate the influence of three-dimensional effects and the blade's rotation.
Three dimensional contact/impact methodology
Kulak, R.F.
1987-01-01
The simulation of three-dimensional interface mechanics between reactor components and structures during static contact or dynamic impact is necessary to realistically evaluate their structural integrity to off-normal loads. In our studies of postulated core energy release events, we have found that significant structure-structure interactions occur in some reactor vessel head closure designs and that fluid-structure interactions occur within the reactor vessel. Other examples in which three-dimensional interface mechanics play an important role are: (1) impact response of shipping casks containing spent fuel, (2) whipping pipe impact on reinforced concrete panels or pipe-to-pipe impact after a pipe break, (3) aircraft crash on secondary containment structures, (4) missiles generated by turbine failures or tornados, and (5) drops of heavy components due to lifting accidents. The above is a partial list of reactor safety problems that require adequate treatment of interface mechanics and are discussed in this paper.
Three Dimensional Particle Tracking in Superfluid Helium
NASA Astrophysics Data System (ADS)
Megson, Peter
2016-11-01
Superfluid helium is a macroscopic quantum state which exhibits exotic physical properties, such as flow without friction and ballistic heat transport. Superfluid flow is irrotational except about line-like topological phase defects with quantized circulation, known as quatized vortices. The presence of these vortices and their dynamics is the dominating factor of turbulence in superfluid flows. One commonly studied regime of superfluid turbulence is thermal counterflow, where a local heat flux drives the formation and growth of a tangle of vortices. This talk will present experimental studies of counterflow turbulence performed using a multi-camera three-dimensional imaging apparatus with micron-sized ice tracer particles as well as fluorescent nanoparticles. In particular, we will discuss the measurement of three-dimensional velocties and their autocorrelations. Additionally, we are developing new techniques for optical studies of bulk superfluid helium, with particular focus on characterizing tracer particles and particle dispersal mechanisms. Funding from NSF DMR-1407472.
Global fitting of power spectra of solar-like stars
NASA Astrophysics Data System (ADS)
Neiner, C.; Appourchaux, T.
2004-01-01
Helioseismology has been able to provide the internal structure of the Sun and its dynamics. These inferences have been made possible by inverting the frequencies and rotational splitting of the p-mode oscillations. Thanks to asteroseismology, similar results can now be obtained for stars other than the Sun. For this purpose, we are developing a numerical code for global fitting of power spectra. The code is currently developed and tested on full-disk integrated solar data obtained with the SOHO/LOI instrument. It will then be applied to synthetic data from the hare-and-hound exercises of COROT. The final goal is to apply the technique to data of solar-like stars obtained with the COROT and Eddington satellites to infer the internal structure and dynamics of those stars.
Three-dimensional adjustment of trilateration data
NASA Technical Reports Server (NTRS)
Sung, L.-Y.; Jackson, D. D.
1985-01-01
The three-dimensional locations of the monuments in the USGS Hollister trilateration network were adjusted to fit line length observations observed in 1977, using a Bayesian approach, and incorporating prior elevation estimates as data in the adjustment procedure. No significant discrepancies in the measured line lengths were found, but significant elevation adjustments (up to 1.85 m) were needed to fit the length data.
Three-Dimensional Printing in Orthopedic Surgery.
Eltorai, Adam E M; Nguyen, Eric; Daniels, Alan H
2015-11-01
Three-dimensional (3D) printing is emerging as a clinically promising technology for rapid prototyping of surgically implantable products. With this commercially available technology, computed tomography or magnetic resonance images can be used to create graspable objects from 3D reconstructed images. Models can enhance patients' understanding of their pathology and surgeon preoperative planning. Customized implants and casts can be made to match an individual's anatomy. This review outlines 3D printing, its current applications in orthopedics, and promising future directions.
Mineralized Three-Dimensional Bone Constructs
NASA Technical Reports Server (NTRS)
Clarke, Mark S. F. (Inventor); Sundaresan, Alamelu (Inventor); Pellis, Neal R. (Inventor)
2013-01-01
The present disclosure provides ex vivo-derived mineralized three-dimensional bone constructs. The bone constructs are obtained by culturing osteoblasts and osteoclast precursors under randomized gravity vector conditions. Preferably, the randomized gravity vector conditions are obtained using a low shear stress rotating bioreactor, such as a High Aspect Ratio Vessel (HARV) culture system. The bone constructs of the disclosure have utility in physiological studies of bone formation and bone function, in drug discovery, and in orthopedics.
Mineralized three-dimensional bone constructs
NASA Technical Reports Server (NTRS)
Clarke, Mark S. F. (Inventor); Sundaresan, Alamelu (Inventor); Pellis, Neal R. (Inventor)
2011-01-01
The present disclosure provides ex vivo-derived mineralized three-dimensional bone constructs. The bone constructs are obtained by culturing osteoblasts and osteoclast precursors under randomized gravity vector conditions. Preferably, the randomized gravity vector conditions are obtained using a low shear stress rotating bioreactor, such as a High Aspect Ratio Vessel (HARV) culture system. The bone constructs of the disclosure have utility in physiological studies of bone formation and bone function, in drug discovery, and in orthopedics.
Real Imagery as a Three Dimensional Display
1991-12-01
under two categories--stereoscopic and autostereoscopic displays. The difference between these two displays is that autostereoscopic displays do not...require the use of special viewing glasses whereas stereoscopic displays do. In order to place a minimum incumbrance on the viewer, the autostereoscopic ...fooled into believing that the scene is three dimensional. This is accomplished even though the second view that normally comes with an autostereoscopic
Three-dimensional ballistocardiography in weightlessness
NASA Technical Reports Server (NTRS)
Scano, A.
1981-01-01
An experiment is described the aim of which is to record a three dimensional ballistocardiogram under the condition of weightlessness and to compare it with tracings recorded on the same subject on the ground as a means of clarifying the meaning of ballistocardiogram waves in different physiological and perphaps pathological conditions. Another purpose is to investigate cardiovascular and possibly fluid adaptations to weightlessness from data collected almost simultaneously on the same subjects during the other cardiovascular during the other cardiovascular and metabolic experiments.
Three-dimensional simulation of vortex breakdown
NASA Technical Reports Server (NTRS)
Kuruvila, G.; Salas, M. D.
1990-01-01
The integral form of the complete, unsteady, compressible, three-dimensional Navier-Stokes equations in the conservation form, cast in generalized coordinate system, are solved, numerically, to simulate the vortex breakdown phenomenon. The inviscid fluxes are discretized using Roe's upwind-biased flux-difference splitting scheme and the viscous fluxes are discretized using central differencing. Time integration is performed using a backward Euler ADI (alternating direction implicit) scheme. A full approximation multigrid is used to accelerate the convergence to steady state.
Three-dimensional display of document set
Lantrip, David B.; Pennock, Kelly A.; Pottier, Marc C.; Schur, Anne; Thomas, James J.; Wise, James A.
2006-09-26
A method for spatializing text content for enhanced visual browsing and analysis. The invention is applied to large text document corpora such as digital libraries, regulations and procedures, archived reports, and the like. The text content from these sources may e transformed to a spatial representation that preserves informational characteristics from the documents. The three-dimensional representation may then be visually browsed and analyzed in ways that avoid language processing and that reduce the analysts' effort.
Three-dimensional display of document set
Lantrip, David B [Oxnard, CA; Pennock, Kelly A [Richland, WA; Pottier, Marc C [Richland, WA; Schur, Anne [Richland, WA; Thomas, James J [Richland, WA; Wise, James A [Richland, WA
2001-10-02
A method for spatializing text content for enhanced visual browsing and analysis. The invention is applied to large text document corpora such as digital libraries, regulations and procedures, archived reports, and the like. The text content from these sources may be transformed to a spatial representation that preserves informational characteristics from the documents. The three-dimensional representation may then be visually browsed and analyzed in ways that avoid language processing and that reduce the analysts' effort.
Three-dimensional display of document set
Lantrip, David B.; Pennock, Kelly A.; Pottier, Marc C.; Schur, Anne; Thomas, James J.; Wise, James A.; York, Jeremy
2009-06-30
A method for spatializing text content for enhanced visual browsing and analysis. The invention is applied to large text document corpora such as digital libraries, regulations and procedures, archived reports, and the like. The text content from these sources may be transformed to a spatial representation that preserves informational characteristics from the documents. The three-dimensional representation may then be visually browsed and analyzed in ways that avoid language processing and that reduce the analysts' effort.
Three-Dimensional Dispaly Of Document Set
Lantrip, David B.; Pennock, Kelly A.; Pottier, Marc C.; Schur, Anne; Thomas, James J.; Wise, James A.
2003-06-24
A method for spatializing text content for enhanced visual browsing and analysis. The invention is applied to large text document corpora such as digital libraries, regulations and procedures, archived reports, and the like. The text content from these sources may be transformed to a spatial representation that preserves informational characteristics from the documents. The three-dimensional representation may then be visually browsed and analyzed in ways that avoid language processing and that reduce the analysts' effort.
Three Dimensional Inverse Synthetic Aperture Radar Imaging
1995-12-01
to upsample the projection data in order to get sufficient image quality. Working within these memory constraints, three-dimensional images were... metallic film on the windscreen in order to block reflections from the cockpit. Photographs and scale drawings of the model are shown in Figures 11 and...as well as spurious responses in the final image. Theoretically, sufficient resolution should have been available without upsampling the original data
Method and apparatus for three dimensional braiding
NASA Technical Reports Server (NTRS)
Farley, Gary L. (Inventor)
1997-01-01
A machine for three-dimensional braiding of fibers is provided in which carrier members travel on a curved, segmented and movable braiding surface. The carrier members are capable of independent, self-propelled motion along the braiding surface. Carrier member position on the braiding surface is controlled and monitored by computer. Also disclosed is a yarn take-up device capable of maintaining tension in the braiding fiber.
Method and apparatus for three dimensional braiding
NASA Technical Reports Server (NTRS)
Farley, Gary L. (Inventor)
1995-01-01
A machine for three-dimensional braiding of fibers is provided in which carrier members travel on a curved, segmented and movable braiding surface. The carrier members are capable of independent, self-propelled motion along the braiding surface. Carrier member position on the braiding surface is controlled and monitored by computer. Also disclosed is a yarn take-up device capable of maintaining tension in the braiding fiber.
Three-dimensional motor schema based navigation
NASA Technical Reports Server (NTRS)
Arkin, Ronald C.
1989-01-01
Reactive schema-based navigation is possible in space domains by extending the methods developed for ground-based navigation found within the Autonomous Robot Architecture (AuRA). Reformulation of two dimensional motor schemas for three dimensional applications is a straightforward process. The manifold advantages of schema-based control persist, including modular development, amenability to distributed processing, and responsiveness to environmental sensing. Simulation results show the feasibility of this methodology for space docking operations in a cluttered work area.
Three-Dimensional (3D) Distribution
2009-03-11
witnessed by ongoing efforts in both Afghanistan and Iraq , must turn distribution challenges into opportunities by mastering Three-Dimensional (3D...sustainment. 5 Joint Logistics Functions •Supply •Services •Maintenance •Transportation • Health Service Support •General Engineering Joint Personnel...Maintenance •Transportation • Health Service Support •Explosive Ordinance Disposal •Human Resource Support •Legal Support •Religious Support •Financial
Lossless compression for three-dimensional images
NASA Astrophysics Data System (ADS)
Tang, Xiaoli; Pearlman, William A.
2004-01-01
We investigate and compare the performance of several three-dimensional (3D) embedded wavelet algorithms on lossless 3D image compression. The algorithms are Asymmetric Tree Three-Dimensional Set Partitioning In Hierarchical Trees (AT-3DSPIHT), Three-Dimensional Set Partitioned Embedded bloCK (3D-SPECK), Three-Dimensional Context-Based Embedded Zerotrees of Wavelet coefficients (3D-CB-EZW), and JPEG2000 Part II for multi-component images. Two kinds of images are investigated in our study -- 8-bit CT and MR medical images and 16-bit AVIRIS hyperspectral images. First, the performances by using different size of coding units are compared. It shows that increasing the size of coding unit improves the performance somewhat. Second, the performances by using different integer wavelet transforms are compared for AT-3DSPIHT, 3D-SPECK and 3D-CB-EZW. None of the considered filters always performs the best for all data sets and algorithms. At last, we compare the different lossless compression algorithms by applying integer wavelet transform on the entire image volumes. For 8-bit medical image volumes, AT-3DSPIHT performs the best almost all the time, achieving average of 12% decreases in file size compared with JPEG2000 multi-component, the second performer. For 16-bit hyperspectral images, AT-3DSPIHT always performs the best, yielding average 5.8% and 8.9% decreases in file size compared with 3D-SPECK and JPEG2000 multi-component, respectively. Two 2D compression algorithms, JPEG2000 and UNIX zip, are also included for reference, and all 3D algorithms perform much better than 2D algorithms.
Three-dimensional magnetic field annihilation
NASA Astrophysics Data System (ADS)
Jardine, M.; Allen, H. R.; Grundy, R. E.
1993-11-01
We present a family of three-dimensional nonlinear solutions for magnetic field annihilation in a current sheet, including the effects of resistivity and viscosity. The different members of the family are characterized by the imposed vorticity of the flow that brings the field lines together. Since in a three- dimensional flow the vorticity can be increased by the stretching of vortex lines (an effect that is absent in two dimensions), we find some striking differences to our previous two-dimensional analysis. In both the two-dimensional and three-dimensional analyses, above a certain critical imposed vorticity omegacrit, the flow breaks up into cells with current sheet is completely altered. In the two-dimensional analysis, omegacrit is a steeply increasing function of the viscous Reynolds number R, whereas in the three-dimensional case, it quickly asymptotes to only omegacrit = 2v0/L where v0 and L are the characteristic velocity and length scale of the flow, respectively. The width of the current sheet, which depends on the speed at which field lines are carried into it, also responds differently to an increase in R. In two dimensions, the current sheet narrows for all vorticities, but three dimensions, it narrows when the imposed vorticity is negative and widens when it is positive. Also we find that the current density within the current sheet varies as the nature of the flow is changed, rather than being constant as in the the two-dimensional case. Finally, we find that there is a minimum value of the plasma beta betamin below which the plasma pressure is negative. For the nonsheared (neutral current sheet) case, betamin increases rapidly with the magnetic Reynolds number Rm such that this type of annihilation is only possible for a high-beta plasma. For a sheared magnetic field, however, betamin is much lower, making this type of annihilation more relevant to the sonar corona.
Three-Dimensional Shallow Water Acoustics
2015-09-30
1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Three-Dimensional Shallow Water Acoustics Dr. Ying...model to predict acoustic fluctuations and derive sound pressure sensitivity kernels due to 3-D sound speed perturbation in the water column. The...numerical method to be utilized is a tangent linear solution to predict acoustic fluctuations due to 3-D sound speed perturbation in the water column. This
Multiparallel Three-Dimensional Optical Microscopy
NASA Technical Reports Server (NTRS)
Nguyen, Lam K.; Price, Jeffrey H.; Kellner, Albert L.; Bravo-Zanoquera, Miguel
2010-01-01
Multiparallel three-dimensional optical microscopy is a method of forming an approximate three-dimensional image of a microscope sample as a collection of images from different depths through the sample. The imaging apparatus includes a single microscope plus an assembly of beam splitters and mirrors that divide the output of the microscope into multiple channels. An imaging array of photodetectors in each channel is located at a different distance along the optical path from the microscope, corresponding to a focal plane at a different depth within the sample. The optical path leading to each photodetector array also includes lenses to compensate for the variation of magnification with distance so that the images ultimately formed on all the photodetector arrays are of the same magnification. The use of optical components common to multiple channels in a simple geometry makes it possible to obtain high light-transmission efficiency with an optically and mechanically simple assembly. In addition, because images can be read out simultaneously from all the photodetector arrays, the apparatus can support three-dimensional imaging at a high scanning rate.
Three-dimensional printing of the retina
Lorber, Barbara; Hsiao, Wen-Kai; Martin, Keith R.
2016-01-01
Purpose of review Biological three-dimensional printing has received a lot of media attention over recent years with advances made in printing cellular structures, including skin and heart tissue for transplantation. Although limitations exist in creating functioning organs with this method, the hope has been raised that creating a functional retina to cure blindness is within reach. The present review provides an update on the advances made toward this goal. Recent findings It has recently been shown that two types of retinal cells, retinal ganglion cells and glial cells, can be successfully printed using a piezoelectric inkjet printer. Importantly, the cells remained viable and did not change certain phenotypic features as a result of the printing process. In addition, recent advances in the creation of complex and viable three-dimensional cellular structures have been made. Summary Some first promising steps toward the creation of a functional retina have been taken. It now needs to be investigated whether recent findings can be extended to other cells of the retina, including those derived from human tissue, and if a complex and viable retinal structure can be created through three-dimensional printing. PMID:27045545
Reconfigurable, braced, three-dimensional DNA nanostructures.
Goodman, Russell P; Heilemann, Mike; Doose, Sören; Erben, Christoph M; Kapanidis, Achillefs N; Turberfield, Andrew J
2008-02-01
DNA nanotechnology makes use of the exquisite self-recognition of DNA in order to build on a molecular scale. Although static structures may find applications in structural biology and computer science, many applications in nanomedicine and nanorobotics require the additional capacity for controlled three-dimensional movement. DNA architectures can span three dimensions and DNA devices are capable of movement, but active control of well-defined three-dimensional structures has not been achieved. We demonstrate the operation of reconfigurable DNA tetrahedra whose shapes change precisely and reversibly in response to specific molecular signals. Shape changes are confirmed by gel electrophoresis and by bulk and single-molecule Förster resonance energy transfer measurements. DNA tetrahedra are natural building blocks for three-dimensional construction; they may be synthesized rapidly with high yield of a single stereoisomer, and their triangulated architecture conveys structural stability. The introduction of shape-changing structural modules opens new avenues for the manipulation of matter on the nanometre scale.
Three-Dimensional Audio Client Library
NASA Technical Reports Server (NTRS)
Rizzi, Stephen A.
2005-01-01
The Three-Dimensional Audio Client Library (3DAudio library) is a group of software routines written to facilitate development of both stand-alone (audio only) and immersive virtual-reality application programs that utilize three-dimensional audio displays. The library is intended to enable the development of three-dimensional audio client application programs by use of a code base common to multiple audio server computers. The 3DAudio library calls vendor-specific audio client libraries and currently supports the AuSIM Gold-Server and Lake Huron audio servers. 3DAudio library routines contain common functions for (1) initiation and termination of a client/audio server session, (2) configuration-file input, (3) positioning functions, (4) coordinate transformations, (5) audio transport functions, (6) rendering functions, (7) debugging functions, and (8) event-list-sequencing functions. The 3DAudio software is written in the C++ programming language and currently operates under the Linux, IRIX, and Windows operating systems.
Three-dimensional deformation of orthodontic brackets
Melenka, Garrett W; Nobes, David S; Major, Paul W
2013-01-01
Braces are used by orthodontists to correct the misalignment of teeth in the mouth. Archwire rotation is a particular procedure used to correct tooth inclination. Wire rotation can result in deformation to the orthodontic brackets, and an orthodontic torque simulator has been designed to examine this wire–bracket interaction. An optical technique has been employed to measure the deformation due to size and geometric constraints of the orthodontic brackets. Images of orthodontic brackets are collected using a stereo microscope and two charge-coupled device cameras, and deformation of orthodontic brackets is measured using a three-dimensional digital image correlation technique. The three-dimensional deformation of orthodontic brackets will be evaluated. The repeatability of the three-dimensional digital image correlation measurement method was evaluated by performing 30 archwire rotation tests using the same bracket and archwire. Finally, five Damon 3MX and five In-Ovation R self-ligating brackets will be compared using this technique to demonstrate the effect of archwire rotation on bracket design. PMID:23762201
Three-Dimensional Imaging. Chapter 10
NASA Technical Reports Server (NTRS)
Kelso, R. M.; Delo, C.
1999-01-01
This chapter is concerned with three-dimensional imaging of fluid flows. Although relatively young, this field of research has already yielded an enormous range of techniques. These vary widely in cost and complexity, with the cheapest light sheet systems being within the budgets of most laboratories, and the most expensive Magnetic Resonance Imaging systems available to a select few. Taking the view that the most likely systems to be developed are those using light sheets, the authors will relate their knowledge and experience of such systems. Other systems will be described briefly and references provided. Flows are inherently three-dimensional in structure; even those generated around nominally 2-D surface geometry. It is becoming increasingly apparent to scientists and engineers that the three-dimensionalities, both large and small scale, are important in terms of overall flow structure and species, momentum, and energy transport. Furthermore, we are accustomed to seeing the world in three dimensions, so it is natural that we should wish to view, measure and interpret flows in three-dimensions. Unfortunately, 3-D images do not lend themselves to convenient presentation on the printed page, and this task is one of the challenges facing us.
Volumetric Three-Dimensional Display Systems
NASA Astrophysics Data System (ADS)
Blundell, Barry G.; Schwarz, Adam J.
2000-03-01
A comprehensive study of approaches to three-dimensional visualization by volumetric display systems This groundbreaking volume provides an unbiased and in-depth discussion on a broad range of volumetric three-dimensional display systems. It examines the history, development, design, and future of these displays, and considers their potential for application to key areas in which visualization plays a major role. Drawing substantially on material that was previously unpublished or available only in patent form, the authors establish the first comprehensive technical and mathematical formalization of the field, and examine a number of different volumetric architectures. System level design strategies are presented, from which proposals for the next generation of high-definition predictable volumetric systems are developed. To ensure that researchers will benefit from work already completed, they provide: * Descriptions of several recent volumetric display systems prepared from material supplied by the teams that created them * An abstract volumetric display system design paradigm * An historical summary of 90 years of development in volumetric display system technology * An assessment of the strengths and weaknesses of many of the systems proposed to date * A unified presentation of the underlying principles of volumetric display systems * A comprehensive bibliography Beautifully supplemented with 17 color plates that illustrate volumetric images and prototype displays, Volumetric Three-Dimensional Display Systems is an indispensable resource for professionals in imaging systems development, scientific visualization, medical imaging, computer graphics, aerospace, military planning, and CAD/CAE.
Three-Dimensional Magnetohydrodynamic Simulation of Slapper Initiation Systems
Christensen, J S; Hrousis, C A
2010-03-09
Although useful information can be gleaned from 2D and even 1D simulations of slapper type initiation systems, these systems are inherently three-dimensional and therefore require full 3D representation to model all relevant details. Further, such representation provides additional insight into optimizing the design of such devices from a first-principles perspective and can thereby reduce experimental costs. We discuss in this paper several ongoing efforts in modeling these systems, our pursuit of validation, and extension of these methods to other systems. Our results show the substantial dependence upon highly accurate global equations of state and resistivity models in these analyses.
Quantitative three-dimensional low-speed wake surveys
NASA Technical Reports Server (NTRS)
Brune, G. W.
1992-01-01
Theoretical and practical aspects of conducting three-dimensional wake measurements in large wind tunnels are reviewed with emphasis on applications in low-speed aerodynamics. Such quantitative wake surveys furnish separate values for the components of drag, such as profile drag and induced drag, but also measure lift without the use of a balance. In addition to global data, details of the wake flowfield as well as spanwise distributions of lift and drag are obtained. The paper demonstrates the value of this measurement technique using data from wake measurements conducted by Boeing on a variety of low-speed configurations including the complex high-lift system of a transport aircraft.
Three-dimensional stereo by photometric ratios
Wolff, L.B.; Angelopoulou, E.
1994-11-01
We present a methodology for corresponding a dense set of points on an object surface from photometric values for three-dimensional stereo computation of depth. The methodology utilizes multiple stereo pairs of images, with each stereo pair being taken of the identical scene but under different illumination. With just two stereo pairs of images taken under two different illumination conditions, a stereo pair of ratio images can be produced, one for the ratio of left-hand images and one for the ratio of right-hand images. We demonstrate how the photometric ratios composing these images can be used for accurate correspondence of object points. Object points having the same photometric ratio with respect to two different illumination conditions constitute a well-defined equivalence class of physical constraints defined by local surface orientation relative to illumination conditions. We formally show that for diffuse reflection the photometric ratio is invariant to varying camera characteristics, surface albedo, and viewpoint and that therefore the same photometric ratio in both images of a stereo pair implies the same equivalence class of physical constraints. The correspondence of photometric ratios along epipolar lines in a stereo pair of images under different illumination conditions is a correspondence of equivalent physical constraints, and the determination of depth from stereo can be performed. Whereas illumination planning is required, our photometric-based stereo methodology does not require knowledge of illumination conditions in the actual computation of three-dimensional depth and is applicable to perspective views. This technique extends the stereo determination of three-dimensional depth to smooth featureless surfaces without the use of precisely calibrated lighting. We demonstrate experimental depth maps from a dense set of points on smooth objects of known ground-truth shape, determined to within 1% depth accuracy.
Three-dimensional flow about penguin wings
NASA Astrophysics Data System (ADS)
Noca, Flavio; Sudki, Bassem; Lauria, Michel
2012-11-01
Penguins, contrary to airborne birds, do not need to compensate for gravity. Yet, the kinematics of their wings is highly three-dimensional and seems exceedingly complex for plain swimming. Is such kinematics the result of an evolutionary optimization or is it just a forced adaptation of an airborne flying apparatus to underwater swimming? Some answers will be provided based on flow dynamics around robotic penguin wings. Updates will also be presented on the development of a novel robotic arm intended to simulate penguin swimming and enable novel propulsion devices.
Three-dimensional ultrasonic colloidal crystals
NASA Astrophysics Data System (ADS)
Caleap, Mihai; Drinkwater, Bruce W.
2016-05-01
Colloidal assembly represents a powerful method for the fabrication of functional materials. In this article, we describe how acoustic radiation forces can guide the assembly of colloidal particles into structures that serve as microscopic elements in novel acoustic metadevices or act as phononic crystals. Using a simple three-dimensional orthogonal system, we show that a diversity of colloidal structures with orthorhombic symmetry can be assembled with megahertz-frequency (MHz) standing pressure waves. These structures allow rapid tuning of acoustic properties and provide a new platform for dynamic metamaterial applications.
Electrode With Porous Three-Dimensional Support
Bernard, Patrick; Dauchier, Jean-Michel; Simonneau, Olivier
1999-07-27
Electrode including a paste containing particles of electrochemically active material and a conductive support consisting of a three-dimensional porous material comprising strands delimiting contiguous pores communicating via passages, characterized in that the average width L in .mu.m of said passages is related to the average diameter .O slashed. in .mu.m of said particles by the following equation, in which W and Y are dimensionless coefficients: wherein W=0.16 Y=1.69 X=202.4 .mu.m and Z=80 .mu.m
Three-dimensional simulations of burning thermals
NASA Astrophysics Data System (ADS)
Aspden, Andy; Bell, John; Woosley, Stan
2010-11-01
Flame ignition in type Ia supernovae (SNe Ia) leads to isolated bubbles of burning buoyant fluid. As a bubble rises due to gravity, it becomes deformed by shear instabilities and transitions to a turbulent buoyant vortex ring. Morton, Taylor and Turner (1956) introduced the entrainment assumption, which can be applied to inert thermals. In this study, we use the entrainment assumption, suitably modified to account for burning, to predict the late-time asymptotic behaviour of these turbulent buoyant vortex rings in SNe Ia. The theory is validated against three- dimensional simulations with adaptive mesh refinement at effective resolutions up to 4096^3.
Three-dimensional relativistic electromagnetic subcycle solitons.
Esirkepov, Timur; Nishihara, Katsunobu; Bulanov, Sergei V; Pegoraro, Francesco
2002-12-30
Three-dimensional (3D) relativistic electromagnetic subcycle solitons were observed in 3D particle-in-cell simulations of an intense short-laser-pulse propagation in an underdense plasma. Their structure resembles that of an oscillating electric dipole with a poloidal electric field and a toroidal magnetic field that oscillate in phase with the electron density with frequency below the Langmuir frequency. On the ion time scale, the soliton undergoes a Coulomb explosion of its core, resulting in ion acceleration, and then evolves into a slowly expanding quasineutral cavity.
High resolution three-dimensional doping profiler
Thundat, Thomas G.; Warmack, Robert J.
1999-01-01
A semiconductor doping profiler provides a Schottky contact at one surface and an ohmic contact at the other. While the two contacts are coupled to a power source, thereby establishing an electrical bias in the semiconductor, a localized light source illuminates the semiconductor to induce a photocurrent. The photocurrent changes in accordance with the doping characteristics of the semiconductor in the illuminated region. By changing the voltage of the power source the depth of the depletion layer can be varied to provide a three dimensional view of the local properties of the semiconductor.
Localization and Dualities in Three-dimensional Superconformal Field Theories
NASA Astrophysics Data System (ADS)
Willett, Brian
In this thesis we apply the technique of localization to three-dimensional N = 2 superconformal field theories. We consider both theories which are exactly superconformal, and those which are believed to flow to nontrivial superconformal fixed points, for which we consider implicitly these fixed points. We find that in such theories, the partition function and certain supersymmetric observables, such as Wilson loops, can be computed exactly by a matrix model. This matrix model consists of an integral over g , the Lie algebra of the gauge group of the theory, of a certain product of 1-loop factors and classical contributions. One can also consider a space of supersymmetric deformations of the partition function corresponding to the set of abelian global symmetries. In the second part of the thesis we apply these results to test dualities. We start with the case of ABJM theory, which is dual to M-theory on an asymptotically AdS4 x S7 background. We extract strong coupling results in the field theory, which can be compared to semiclassical, weak coupling results in the gravity theory, and a nontrivial agreement is found. We also consider several classes of dualities between two three-dimensional field theories, namely, 3D mirror symmetry, Aharony duality, and Giveon-Kutasov duality. Here the dualities are typically between the IR limits of two Yang-Mills theories, which are strongly coupled in three dimensions since Yang-Mills theory is asymptotically free here. Thus the comparison is again very nontrivial, and relies on the exactness of the localization computation. We also compare the deformed partition functions, which tests the mapping of global symmetries of the dual theories. Finally, we discuss some recent progress in the understanding of general three-dimensional theories in the form of the F-theorem, a conjectured analogy to the a-theorem in four dimensions and c-theorem in two dimensions, which is closely related to the localization computation.
Symmetries in Three-Dimensional Superconformal Quantum Field Theories
NASA Astrophysics Data System (ADS)
Bashkirov, Denis
Many examples of gauge-gravity duality and quantum equivalences of different-looking three-dimensional Quantum Field Theories indicate the existence of continuous symmetries whose currents are not built from elementary, or perturbative, fields used to write down the Lagrangian. These symmetries are called hidden or nonperturbative. We describe a method for studying continuous symmetries in a large class of three-dimensional supersymmetric gauge theories which, in particular, enables one to explore nonperturbative global symmetries and supersymmetries. As an application of the method, we prove conjectured supersymmetry enhancement in strongly coupled ABJM theory from N = 6 to N = 8 and find additional nonperturbative evidence for its duality to the N = 8 U(N) SYM theory for the minimal value of the Chern-Simons coupling. Hidden supersymmetry is also shown to occur in N = 4 d = 3 SQCD with one fundamental and one adjoint hypermultiplets. An infinite family of N = 6 d = 3 ABJ theories is proved to have hidden N = 8 superconformal symmetry and hidden parity on the quantum level. We test several conjectural dualities between ABJ theories and theories proposed by Bagger and Lambert, and Gustavsson by comparing superconformal indices of these theories. Comparison of superconformal indices is also used to test dualities between N = 2 d = 3 theories proposed by Aharony, the analysis of whose chiral rings teaches some general lessons about nonperturbative chiral operators of strongly coupled 3d supersymmetric gauge theories. As another application of our method we consider examples of hidden global symmetries in a class of quiver three-dimensional N = 4 superconformal gauge theories. Finally, we point out to the relations between some basic propeties of superconformal N ≥ 6 theories and their symmetries. The results presented in this thesis were obtained in a series of papers [1, 2, 3, 4, 5].
Three-dimensional head anthropometric analysis
NASA Astrophysics Data System (ADS)
Enciso, Reyes; Shaw, Alex M.; Neumann, Ulrich; Mah, James
2003-05-01
Currently, two-dimensional photographs are most commonly used to facilitate visualization, assessment and treatment of facial abnormalities in craniofacial care but are subject to errors because of perspective, projection, lack metric and 3-dimensional information. One can find in the literature a variety of methods to generate 3-dimensional facial images such as laser scans, stereo-photogrammetry, infrared imaging and even CT however each of these methods contain inherent limitations and as such no systems are in common clinical use. In this paper we will focus on development of indirect 3-dimensional landmark location and measurement of facial soft-tissue with light-based techniques. In this paper we will statistically evaluate and validate a current three-dimensional image-based face modeling technique using a plaster head model. We will also develop computer graphics tools for indirect anthropometric measurements in a three-dimensional head model (or polygonal mesh) including linear distances currently used in anthropometry. The measurements will be tested against a validated 3-dimensional digitizer (MicroScribe 3DX).
Three-dimensional television: a broadcaster's perspective
NASA Astrophysics Data System (ADS)
Jolly, S. J. E.; Armstrong, M.; Salmon, R. A.
2009-02-01
The recent resurgence of interest in the stereoscopic cinema and the increasing availability to the consumer of stereoscopic televisions and computer displays are leading broadcasters to consider, once again, the feasibility of stereoscopic broadcasting. High Definition Television is now widely deployed, and the R&D departments of broadcasters and consumer electronics manufacturers are starting to plan future enhancements to the experience of television. Improving the perception of depth via stereoscopy is a strong candidate technology. In this paper we will consider the challenges associated with the production, transmission and display of different forms of "three-dimensional" television. We will explore options available to a broadcaster wishing to start a 3D service using the technologies available at the present time, and consider how they could be improved to enable many more television programmes to be recorded and transmitted in a 3D-compatible form, paying particular attention to scenarios such as live broadcasting, where the workflows developed for the stereoscopic cinema are inapplicable. We will also consider the opportunities available for broadcasters to reach audiences with "three-dimensional" content via other media in the near future: for example, distributing content via the existing stereoscopic cinema network, or over the Internet to owners of stereoscopic computer displays.
Two component-three dimensional catalysis
Schwartz, Michael; White, James H.; Sammells, Anthony F.
2002-01-01
This invention relates to catalytic reactor membranes having a gas-impermeable membrane for transport of oxygen anions. The membrane has an oxidation surface and a reduction surface. The membrane is coated on its oxidation surface with an adherent catalyst layer and is optionally coated on its reduction surface with a catalyst that promotes reduction of an oxygen-containing species (e.g., O.sub.2, NO.sub.2, SO.sub.2, etc.) to generate oxygen anions on the membrane. The reactor has an oxidation zone and a reduction zone separated by the membrane. A component of an oxygen containing gas in the reduction zone is reduced at the membrane and a reduced species in a reactant gas in the oxidation zone of the reactor is oxidized. The reactor optionally contains a three-dimensional catalyst in the oxidation zone. The adherent catalyst layer and the three-dimensional catalyst are selected to promote a desired oxidation reaction, particularly a partial oxidation of a hydrocarbon.
Nanowired three-dimensional cardiac patches
NASA Astrophysics Data System (ADS)
Dvir, Tal; Timko, Brian P.; Brigham, Mark D.; Naik, Shreesh R.; Karajanagi, Sandeep S.; Levy, Oren; Jin, Hongwei; Parker, Kevin K.; Langer, Robert; Kohane, Daniel S.
2011-11-01
Engineered cardiac patches for treating damaged heart tissues after a heart attack are normally produced by seeding heart cells within three-dimensional porous biomaterial scaffolds. These biomaterials, which are usually made of either biological polymers such as alginate or synthetic polymers such as poly(lactic acid) (PLA), help cells organize into functioning tissues, but poor conductivity of these materials limits the ability of the patch to contract strongly as a unit. Here, we show that incorporating gold nanowires within alginate scaffolds can bridge the electrically resistant pore walls of alginate and improve electrical communication between adjacent cardiac cells. Tissues grown on these composite matrices were thicker and better aligned than those grown on pristine alginate and when electrically stimulated, the cells in these tissues contracted synchronously. Furthermore, higher levels of the proteins involved in muscle contraction and electrical coupling are detected in the composite matrices. It is expected that the integration of conducting nanowires within three-dimensional scaffolds may improve the therapeutic value of current cardiac patches.
In-lab three-dimensional printing
Partridge, Roland; Conlisk, Noel; Davies, Jamie A.
2012-01-01
The development of the microscope in 1590 by Zacharias Janssenby and Hans Lippershey gave the world a new way of visualizing details of morphogenesis and development. More recent improvements in this technology including confocal microscopy, scanning electron microscopy (SEM) and optical projection tomography (OPT) have enhanced the quality of the resultant image. These technologies also allow a representation to be made of a developing tissue’s three-dimensional (3-D) form. With all these techniques however, the image is delivered on a flat two-dimensional (2-D) screen. 3-D printing represents an exciting potential to reproduce the image not simply on a flat screen, but in a physical, palpable three-dimensional structure. Here we explore the scope that this holds for exploring and interacting with the structure of a developing organ in an entirely novel way. As well as being useful for visualization, 3-D printers are capable of rapidly and cost-effectively producing custom-made structures for use within the laboratory. We here describe the advantages of producing hardware for a tissue culture system using an inexpensive in-lab printer. PMID:22652907
Three dimensional force balance of asymmetric droplets
NASA Astrophysics Data System (ADS)
Kim, Yeseul; Lim, Su Jin; Cho, Kun; Weon, Byung Mook
2016-11-01
An equilibrium contact angle of a droplet is determined by a horizontal force balance among vapor, liquid, and solid, which is known as Young's law. Conventional wetting law is valid only for axis-symmetric droplets, whereas real droplets are often asymmetric. Here we show that three-dimensional geometry must be considered for a force balance for asymmetric droplets. By visualizing asymmetric droplets placed on a free-standing membrane in air with X-ray microscopy, we are able to identify that force balances in one side and in other side control pinning behaviors during evaporation of droplets. We find that X-ray microscopy is powerful for realizing the three-dimensional force balance, which would be essential in interpretation and manipulation of wetting, spreading, and drying dynamics for asymmetric droplets. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2016R1D1A1B01007133).
Three-dimensional turbopump flowfield analysis
NASA Technical Reports Server (NTRS)
Sharma, O. P.; Belford, K. A.; Ni, R. H.
1992-01-01
A program was conducted to develop a flow prediction method applicable to rocket turbopumps. The complex nature of a flowfield in turbopumps is described and examples of flowfields are discussed to illustrate that physics based models and analytical calculation procedures based on computational fluid dynamics (CFD) are needed to develop reliable design procedures for turbopumps. A CFD code developed at NASA ARC was used as the base code. The turbulence model and boundary conditions in the base code were modified, respectively, to: (1) compute transitional flows and account for extra rates of strain, e.g., rotation; and (2) compute surface heat transfer coefficients and allow computation through multistage turbomachines. Benchmark quality data from two and three-dimensional cascades were used to verify the code. The predictive capabilities of the present CFD code were demonstrated by computing the flow through a radial impeller and a multistage axial flow turbine. Results of the program indicate that the present code operated in a two-dimensional mode is a cost effective alternative to full three-dimensional calculations, and that it permits realistic predictions of unsteady loadings and losses for multistage machines.
Three-dimensional terahertz wave imaging.
Zhang, X-C
2004-02-15
Pulsed terahertz (THz) wave sensing and imaging is a coherent measurement technology. Like radar, based on the phase and amplitude of the THz pulse at each frequency, THz waves provide temporal and spectroscopic information that allows us to develop various three-dimensional (3D) terahertz tomographic imaging modalities. The 3D THz tomographic imaging methods we investigated include THz time-of-flight tomography, THz computed tomography (CT) and THz binary lens tomography. THz time-of-flight uses the THz pulses as a probe beam to temporally mark the target, and then constructs a 3D image of the target using the THz waves scattered by the target. THz CT is based on geometrical optics and inspired from X-ray CT. THz binary lens tomography uses the frequency-dependent focal-length property of binary lenses to obtain tomographic images of an object. Three-dimensional THz imaging has potential in such applications as non-destructive inspection. The interaction between a coherent THz pulse and an object provides rich information about the object under study; therefore, 3D THz imaging can be used to inspect or characterize dielectric and semiconductor objects. For example, 3D THz imaging has been used to detect and identify the defects inside a Space Shuttle insulation tile.
Three-dimensional singular points in aerodynamics
NASA Technical Reports Server (NTRS)
Unal, Aynur
1988-01-01
When three-dimensional separation occurs on a body immersed in a flow governed by the incompressible Navier-Stokes equations, the geometrical surfaces formed by the three vector fields (velocity, vorticity and the skin-friction) and a scalar field (pressure) become interrelated through topological maps containing their respective singular points and extremal points. A mathematically consistent description of these singular points becomes inevitable when we want to study the geometry of the separation. A separated stream surface requires, for example, the existence of a saddle-type singular point on the skin-friction surface. This singular point is actually, in the proper language of mathematics, a saddle of index two. The index is a measure of the dimension of the outset (set leaving the singular point). Hence, when a saddle of index two is specified, a two dimensional surface that becomes separated from the osculating plane of the saddle is implied. The three-dimensional singular point is interpreted mathematically and the most common aerodynamical singular points are discussed through this perspective.
Three dimensional quantum geometry and deformed symmetry
NASA Astrophysics Data System (ADS)
Joung, E.; Mourad, J.; Noui, K.
2009-05-01
We study a three dimensional noncommutative space emerging in the context of three dimensional Euclidean quantum gravity. Our starting point is the assumption that the isometry group is deformed to the Drinfeld double D(SU(2)). We generalize to the deformed case the construction of E3 as the quotient of its isometry group ISU(2) by SU(2). We show that the algebra of functions on E3 becomes the noncommutative algebra of SU(2) distributions, C(SU(2))∗, endowed with the convolution product. This construction gives the action of ISU(2) on the algebra and allows the determination of plane waves and coordinate functions. In particular, we show the following: (i) plane waves have bounded momenta; (ii) to a given momentum are associated several SU(2) elements leading to an effective description of ϕ ɛC(SU(2))∗ in terms of several physical scalar fields on E3; (iii) their product leads to a deformed addition rule of momenta consistent with the bound on the spectrum. We generalize to the noncommutative setting the "local" action for a scalar field. Finally, we obtain, using harmonic analysis, another useful description of the algebra as the direct sum of the algebra of matrices. The algebra of matrices inherits the action of ISU(2): rotations leave the order of the matrices invariant, whereas translations change the order in a way we explicitly determine.
Three-dimensional orbit and physical parameters of HD 6840
NASA Astrophysics Data System (ADS)
Wang, Xiao-Li; Ren, Shu-Lin; Fu, Yan-Ning
2016-02-01
HD 6840 is a double-lined visual binary with an orbital period of ˜7.5 years. By fitting the speckle interferometric measurements made by the 6 m BTA telescope and 3.5 m WIYN telescope, Balega et al. gave a preliminary astrometric orbital solution of the system in 2006. Recently, Griffin derived a precise spectroscopic orbital solution from radial velocities observed with OPH and Cambridge Coravel. However, due to the low precision of the determined orbital inclination, the derived component masses are not satisfying. By adding the newly collected astrometric data in the Fourth Catalog of Interferometric Measurements of Binary Stars, we give a three-dimensional orbit solution with high precision and derive the preliminary physical parameters of HD 6840 via a simultaneous fit including both astrometric and radial velocity measurements.
Cyclic and multicyclic polymers by three-dimensional polycondensation.
Kricheldorf, Hans R
2009-08-18
The recent confirmation that polycondensations (and other step-growth polymerizations) of difunctional monomers involve cyclization reactions at any concentration and at any stage of the polymerization also has consequences for three-dimensional polycondensations on multifunctional monomers. It is demonstrated that tree-shaped (hyperbranched) oligomers are gradually transformed into star-shaped polymers with a cyclic core, when the conversion increases. Polycondensations of "a(2) + b(3)" or "a(2) + b(4)" monomer combinations yield multicyclic polymers, when gelation can be avoided. This new architecture may be subdivided into three groups: perfect multicycles free of functional groups, multicycles having b functions, and multicycles having "a" groups. The concrete examples discussed in this Account mainly concern polyethers and polyesters.
THREE-DIMENSIONAL RADIATION TRANSFER IN YOUNG STELLAR OBJECTS
Whitney, B. A.; Honor, J.; Robitaille, T. P.; Bjorkman, J. E.; Dong, R.; Wolff, M. J.; Wood, K.
2013-08-15
We have updated our publicly available dust radiative transfer code (HOCHUNK3D) to include new emission processes and various three-dimensional (3D) geometries appropriate for forming stars. The 3D geometries include warps and spirals in disks, accretion hotspots on the central star, fractal clumping density enhancements, and misaligned inner disks. Additional axisymmetric (2D) features include gaps in disks and envelopes, ''puffed-up inner rims'' in disks, multiple bipolar cavity walls, and iteration of disk vertical structure assuming hydrostatic equilibrium (HSEQ). We include the option for simple power-law envelope geometry, which, combined with fractal clumping and bipolar cavities, can be used to model evolved stars as well as protostars. We include non-thermal emission from polycyclic aromatic hydrocarbons (PAHs) and very small grains, and external illumination from the interstellar radiation field. The grid structure was modified to allow multiple dust species in each cell; based on this, a simple prescription is implemented to model dust stratification. We describe these features in detail, and show example calculations of each. Some of the more interesting results include the following: (1) outflow cavities may be more clumpy than infalling envelopes. (2) PAH emission in high-mass stars may be a better indicator of evolutionary stage than the broadband spectral energy distribution slope; and related to this, (3) externally illuminated clumps and high-mass stars in optically thin clouds can masquerade as young stellar objects. (4) Our HSEQ models suggest that dust settling is likely ubiquitous in T Tauri disks, in agreement with previous observations.
The three-dimensional structure of the infrared cirrus
NASA Technical Reports Server (NTRS)
Gaustad, John E.
1994-01-01
This project was carried out over a period of four years, beginning 6/15/89 and continuing through 9/15/93. Intermediate results have been reported as poster papers at several meetings of the American Astronomical Society. A brief summary was presented in April 1993 at a symposium on the infrared cirrus. The final results were published in late 1993. The measurements have been deposited in NASA's Astronomical Data Center. Briefly, the results are as follows: Using the IRAS data base, we surveyed the 1808 06-B9.5 stars in the Bright Star Catalog for extended excess emission at 60 micrometers, indicating the presence of heated dust (cirrus hotspots) at the location of the star. Measurements of the angular size and infrared flux at 12, 25, 60 and 100 micrometers were obtained for 302 objects. From these basic data we calculated the radius, absorption, optical depth, color temperature, and dust density for each object. Arguing that the stars are randomly distributed point probes of the ISM, we showed that the filling factor of the dust-bearing component of the ISM is 14.6 + 2.4 percent within 400 pc of the sun for clouds with an equivalent hydrogen density greater than 0.5 cm(exp -3). Above a density of 1.0 cm(exp -3) the density distribution function appears to follow a power law of index -1.25. Further, we showed that the dust is distributed more sparsely in a region near the sun about 60 pc wide and extending several hundred parsecs in the direction of longitudes 80-260 deg. The distances to the dust clouds were determined from the spectroscopic parallaxes of the embedded stars; when the HIPPARCOS parallaxes become available, we will be able to produce a more accurate three-dimensional view of the local ISM.
ERIC Educational Resources Information Center
Brown, Daniel
2013-01-01
Visualizing the three-dimensional distribution of stars within a constellation is highly challenging for both students and educators, but when carried out in an interactive collaborative way, it can create an ideal environment to explore common misconceptions about size and scale within astronomy. We present how the common tabletop activities…
Three-dimensional context regulation of metastasis.
Erler, Janine T; Weaver, Valerie M
2009-01-01
Tumor progression ensues within a three-dimensional microenvironment that consists of cellular and non-cellular components. The extracellular matrix (ECM) and hypoxia are two non-cellular components that potently influence metastasis. ECM remodeling and collagen cross-linking stiffen the tissue stroma to promote transformation, tumor growth, motility and invasion, enhance cancer cell survival, enable metastatic dissemination, and facilitate the establishment of tumor cells at distant sites. Matrix degradation can additionally promote malignant progression and metastasis. Tumor hypoxia is functionally linked to altered stromal-epithelial interactions. Hypoxia additionally induces the expression of pro-migratory, survival and invasion genes, and up-regulates expression of ECM components and modifying enzymes, to enhance tumor progression and metastasis. Synergistic interactions between matrix remodeling and tumor hypoxia influence common mechanisms that maximize tumor progression and cooperate to drive metastasis. Thus, clarifying the molecular pathways by which ECM remodeling and tumor hypoxia intersect to promote tumor progression should identify novel therapeutic targets.
Three-dimensional printing physiology laboratory technology
Sulkin, Matthew S.; Widder, Emily; Shao, Connie; Holzem, Katherine M.; Gloschat, Christopher; Gutbrod, Sarah R.
2013-01-01
Since its inception in 19th-century Germany, the physiology laboratory has been a complex and expensive research enterprise involving experts in various fields of science and engineering. Physiology research has been critically dependent on cutting-edge technological support of mechanical, electrical, optical, and more recently computer engineers. Evolution of modern experimental equipment is constrained by lack of direct communication between the physiological community and industry producing this equipment. Fortunately, recent advances in open source technologies, including three-dimensional printing, open source hardware and software, present an exciting opportunity to bring the design and development of research instrumentation to the end user, i.e., life scientists. Here we provide an overview on how to develop customized, cost-effective experimental equipment for physiology laboratories. PMID:24043254
AAOGlimpse: Three-dimensional Data Viewer
NASA Astrophysics Data System (ADS)
Shortridge, Keith
2011-10-01
AAOGlimpse is an experimental display program that uses OpenGL to display FITS data (and even JPEG images) as 3D surfaces that can be rotated and viewed from different angles, all in real-time. It is WCS-compliant and designed to handle three-dimensional data. Each plane in a data cube is surfaced in the same way, and the program allows the user to travel through a cube by 'peeling off' successive planes, or to look into a cube by suppressing the display of data below a given cutoff value. It can blink images and can superimpose images and contour maps from different sources using their world coordinate data. A limited socket interface allows communication with other programs.
Three-dimensional printing physiology laboratory technology.
Sulkin, Matthew S; Widder, Emily; Shao, Connie; Holzem, Katherine M; Gloschat, Christopher; Gutbrod, Sarah R; Efimov, Igor R
2013-12-01
Since its inception in 19th-century Germany, the physiology laboratory has been a complex and expensive research enterprise involving experts in various fields of science and engineering. Physiology research has been critically dependent on cutting-edge technological support of mechanical, electrical, optical, and more recently computer engineers. Evolution of modern experimental equipment is constrained by lack of direct communication between the physiological community and industry producing this equipment. Fortunately, recent advances in open source technologies, including three-dimensional printing, open source hardware and software, present an exciting opportunity to bring the design and development of research instrumentation to the end user, i.e., life scientists. Here we provide an overview on how to develop customized, cost-effective experimental equipment for physiology laboratories.
Versatile three-dimensional cryogenic micropositioning device
NASA Astrophysics Data System (ADS)
Heil, J.; Böhm, A.; Primke, M.; Wyder, P.
1996-01-01
A simple design for a mechanically driven three-dimensional cryogenic micropositioner is presented. The design is based on a parallelogram structure constructed from leaf springs and wires. Actuation is achieved by the elastic deformation of the parallelogram by screws. Positions within a volume of roughly (2 mm)3 are attainable. The precision and reproducibility of positioning are in the μm-range. The deviations from linearity are smaller than 10% for the whole working range and the deviation from orthogonality is smaller than 3°. Calibration measurements performed on a Cu-mesh with a lattice constant of 60 μm are presented. In an experiment investigating the ballistic transport of carriers in the semimetal Bi, two such devices are used. The first one is used as a scanning unit for an optical fiber and the second one is used as micropositioner for a Cu point contact.
Three-dimensional cultured glioma cell lines
NASA Technical Reports Server (NTRS)
Gonda, Steve R. (Inventor); Marley, Garry M. (Inventor)
1991-01-01
Three-dimensional glioma spheroids were produced in vitro with size and histological differentiation previously unattained. The spheroids were grown in liquid media suspension in a Johnson Space Center (JSC) Rotating Wall Bioreactor without using support matrices such as microcarrier beads. Spheroid volumes of greater than 3.5 cu mm and diameters of 2.5 mm were achieved with a viable external layer or rim of proliferating cells, a transitional layer beneath the external layer with histological differentiation, and a degenerative central region with a hypoxic necrotic core. Cell debris was evident in the degenerative central region. The necrotics centers of some of the spheroids had hyaline droplets. Granular bodies were detected predominantly in the necrotic center.
Multiscale modeling of three-dimensional genome
NASA Astrophysics Data System (ADS)
Zhang, Bin; Wolynes, Peter
The genome, the blueprint of life, contains nearly all the information needed to build and maintain an entire organism. A comprehensive understanding of the genome is of paramount interest to human health and will advance progress in many areas, including life sciences, medicine, and biotechnology. The overarching goal of my research is to understand the structure-dynamics-function relationships of the human genome. In this talk, I will be presenting our efforts in moving towards that goal, with a particular emphasis on studying the three-dimensional organization, the structure of the genome with multi-scale approaches. Specifically, I will discuss the reconstruction of genome structures at both interphase and metaphase by making use of data from chromosome conformation capture experiments. Computationally modeling of chromatin fiber at atomistic level from first principles will also be presented as our effort for studying the genome structure from bottom up.
Three-dimensional elastic lidar winds
Buttler, W.T.
1996-07-01
Maximum cross-correlation techniques have been used with satellite data to estimate winds and sea surface velocities for several years. Los Alamos National Laboratory (LANL) is currently using a variation of the basic maximum cross-correlation technique, coupled with a deterministic application of a vector median filter, to measure transverse winds as a function of range and altitude from incoherent elastic backscatter lidar data taken throughout large volumes within the atmospheric boundary layer. Hourly representations of three- dimensional wind fields, derived from elastic lidar data taken during an air-quality study performed in a region of complex terrain near Sunland Park, New Mexico, are presented and compared with results from an Environmental Protection Agency (EPA) approved laser doppler velocimeter. The wind fields showed persistent large scale eddies as well as general terrain following winds in the Rio Grande valley.
Automatic three-dimensional underground mine mapping
Huber, D.F.; Vandapel, N.
2006-01-15
For several years, our research group has been developing methods for automated modeling of three-dimensional environments. In September 2002, we were given the opportunity to demonstrate our mapping capability in an underground coal mine. The opportunity arose as a result of the Quecreek mine accident, in which an inaccurate map caused miners to breach an abandoned, water-filled mine, trapping them for several days. Our field test illustrates the feasibility and potential of high-resolution 3D mapping of an underground coal mine using a cart-mounted 3D laser scanner In this paper we present our experimental setup, the automatic 3D modeling method used, and the results of the field test.
Volumetric techniques: three-dimensional midface modeling
Pierzchała, Ewa; Placek, Waldemar
2014-01-01
Aging is a complex process caused by many factors. The most important factors include exposure to UV radiation, smoking, facial muscle movement, gravity, loss and displacement of fat and bone resorption. As a symptom of aging, face loses elasticity, volume and cheerful look. While changing face proportions, the dominant part of a face is its bottom instead of the mid part. The use of three-dimensional face modelling techniques, particularly the mid-face – tear through and cheeks, restores the skin firmness, volume and healthy look. For this purpose the hyaluronic acid is used, calcium hydroxyapatite, and L-polylactic acid fillers. Volumetric techniques require precision and proper selection of the filling agent to give a sense of satisfaction to both the patient and the doctor. PMID:25610354
Volumetric techniques: three-dimensional midface modeling.
Macierzyńska, Arleta; Pierzchała, Ewa; Placek, Waldemar
2014-12-01
Aging is a complex process caused by many factors. The most important factors include exposure to UV radiation, smoking, facial muscle movement, gravity, loss and displacement of fat and bone resorption. As a symptom of aging, face loses elasticity, volume and cheerful look. While changing face proportions, the dominant part of a face is its bottom instead of the mid part. The use of three-dimensional face modelling techniques, particularly the mid-face - tear through and cheeks, restores the skin firmness, volume and healthy look. For this purpose the hyaluronic acid is used, calcium hydroxyapatite, and L-polylactic acid fillers. Volumetric techniques require precision and proper selection of the filling agent to give a sense of satisfaction to both the patient and the doctor.
Quantum interferometry with three-dimensional geometry.
Spagnolo, Nicolò; Aparo, Lorenzo; Vitelli, Chiara; Crespi, Andrea; Ramponi, Roberta; Osellame, Roberto; Mataloni, Paolo; Sciarrino, Fabio
2012-01-01
Quantum interferometry uses quantum resources to improve phase estimation with respect to classical methods. Here we propose and theoretically investigate a new quantum interferometric scheme based on three-dimensional waveguide devices. These can be implemented by femtosecond laser waveguide writing, recently adopted for quantum applications. In particular, multiarm interferometers include "tritter" and "quarter" as basic elements, corresponding to the generalization of a beam splitter to a 3- and 4-port splitter, respectively. By injecting Fock states in the input ports of such interferometers, fringe patterns characterized by nonclassical visibilities are expected. This enables outperforming the quantum Fisher information obtained with classical fields in phase estimation. We also discuss the possibility of achieving the simultaneous estimation of more than one optical phase. This approach is expected to open new perspectives to quantum enhanced sensing and metrology performed in integrated photonics.
Quantum interferometry with three-dimensional geometry
Spagnolo, Nicolò; Aparo, Lorenzo; Vitelli, Chiara; Crespi, Andrea; Ramponi, Roberta; Osellame, Roberto; Mataloni, Paolo; Sciarrino, Fabio
2012-01-01
Quantum interferometry uses quantum resources to improve phase estimation with respect to classical methods. Here we propose and theoretically investigate a new quantum interferometric scheme based on three-dimensional waveguide devices. These can be implemented by femtosecond laser waveguide writing, recently adopted for quantum applications. In particular, multiarm interferometers include “tritter” and “quarter” as basic elements, corresponding to the generalization of a beam splitter to a 3- and 4-port splitter, respectively. By injecting Fock states in the input ports of such interferometers, fringe patterns characterized by nonclassical visibilities are expected. This enables outperforming the quantum Fisher information obtained with classical fields in phase estimation. We also discuss the possibility of achieving the simultaneous estimation of more than one optical phase. This approach is expected to open new perspectives to quantum enhanced sensing and metrology performed in integrated photonics. PMID:23181189
Scaffolding for Three-Dimensional Embryonic Vasculogenesis
NASA Astrophysics Data System (ADS)
Kraehenbuehl, Thomas P.; Aday, Sezin; Ferreira, Lino S.
Biomaterial scaffolds have great potential to support efficient vascular differentiation of embryonic stem cells. Vascular cell fate-specific biochemical and biophysical cues have been identified and incorporated into three-dimensional (3D) biomaterials to efficiently direct embryonic vasculogenesis. The resulting vascular-like tissue can be used for regenerative medicine applications, further elucidation of biophysical and biochemical cues governing vasculogenesis, and drug discovery. In this chapter, we give an overview on the following: (1) developmental cues for directed differentiation of human embryonic stem cells (hESCs) into vascular cells, (2) 3D vascular differentiation in embryoid bodies (EBs), (3) preparation of 3D scaffolds for the vascular differentiation of hESCs, and (4) the most significant studies combining scaffolding and hESCs for development of vascular-like tissue.
Three-Dimensional Gear Crack Propagation Studies
NASA Technical Reports Server (NTRS)
Lewicki, David G.; Sane, Ashok D.; Drago, Raymond J.; Wawrzynek, Paul A.
1998-01-01
Three-dimensional crack growth simulation was performed on a split-tooth gear design using boundary element modeling and linear elastic fracture mechanics. Initial cracks in the fillet of the teeth produced stress intensity factors of greater magnitude (and thus, greater crack growth rates) than those in the root or groove areas of the teeth. Crack growth simulation was performed on a case study to evaluate crack propagation paths. Tooth fracture was predicted from the crack growth simulation for an initial crack in the tooth fillet region. Tooth loads on the uncracked mesh of the split-tooth design were up to five times greater than those on the cracked mesh if equal deflections of the cracked and uncracked teeth were considered. Predicted crack shapes as well as crack propagation life are presented based on calculated stress intensity factors, mixed-mode crack propagation trajectory theories, and fatigue crack growth theories.
The Three-Dimensional EIT Wave
NASA Technical Reports Server (NTRS)
Thompson, B. J.; Biesecker, D. A.; Gilbert, H. R.; Lawrence, G. R.; Ofman, L.; Wu, S. T.; Warmuth, A.; Fisher, Richard R. (Technical Monitor)
2002-01-01
An EIT wave is an impulsive disturbance which has been observed in the EUV, Soft X-ray and white light corona, with corresponding observations in the chromosphere. The effects of these disturbances can be observed across the entire solar disk of the Sun, and throughout the inner heliosphere as well. However, the picture is not complete; observations alone do not establish a complete understanding of the nature of this three-dimensional phenomenon. A number of associated phenomena have been documented, though in most cases causality has not determined. Additionally, it is unclear which factors govern the impulse's ability to affect regions of the corona and heliosphere. We discuss the various observations and the models which provided links between the associated phenomena.
Three-dimensional hologram display system
NASA Technical Reports Server (NTRS)
Mintz, Frederick (Inventor); Chao, Tien-Hsin (Inventor); Bryant, Nevin (Inventor); Tsou, Peter (Inventor)
2009-01-01
The present invention relates to a three-dimensional (3D) hologram display system. The 3D hologram display system includes a projector device for projecting an image upon a display medium to form a 3D hologram. The 3D hologram is formed such that a viewer can view the holographic image from multiple angles up to 360 degrees. Multiple display media are described, namely a spinning diffusive screen, a circular diffuser screen, and an aerogel. The spinning diffusive screen utilizes spatial light modulators to control the image such that the 3D image is displayed on the rotating screen in a time-multiplexing manner. The circular diffuser screen includes multiple, simultaneously-operated projectors to project the image onto the circular diffuser screen from a plurality of locations, thereby forming the 3D image. The aerogel can use the projection device described as applicable to either the spinning diffusive screen or the circular diffuser screen.
Magneto Transport in Three Dimensional Carbon Nanostructures
NASA Astrophysics Data System (ADS)
Datta, Timir; Wang, Lei; Jaroszynski, Jan; Yin, Ming; Alameri, Dheyaa
Electrical properties of self-assembled three dimensional nanostructures are interesting topic. Here we report temperature dependence of magneto transport in such carbon nanostructures with periodic spherical voids. Specimens with different void diameters in the temperature range from 200 mK to 20 K were studied. Above 2 K, magnetoresistance, MR = [R(B) - R(0)] / R(0), crosses over from quadratic to a linear dependence with the increase of magnetic field [Wang et al., APL 2015; DOI:10.1063/1.4926606]. We observe MR to be non-saturating even up to 18 Tesla. Furthermore, MR demonstrates universality because all experimental data can be collapsed on to a single curve, as a universal function of B/T. Below 2 K, magnetoresistance saturates with increasing field. Quantum Hall like steps are also observed in this low temperature regime. Remarkably, MR of our sample displays orientation independence, an attractive feature for technological applications.
Three dimensional carbon-nanotube polymers.
Zhao, Zhisheng; Xu, Bo; Wang, Li-Min; Zhou, Xiang-Feng; He, Julong; Liu, Zhongyuan; Wang, Hui-Tian; Tian, Yongjun
2011-09-27
Eight fascinating sp(2)- and sp(3)-hybridized carbon allotropes have been uncovered using a newly developed ab initio particle-swarm optimization methodology for crystal structure prediction. These crystalline allotropes can be viewed respectively as three-dimensional (3D) polymers of (4,0), (5,0), (7,0), (8,0), (9,0), (3,3), (4,4), and (6,6) carbon nanotubes, termed 3D-(n, 0) or 3D-(n, n) carbons. The ground-state energy calculations show that the carbons all have lower energies than C(60) fullerene, and some are energetically more stable than the van der Waals packing configurations of their nanotube parents. Owing to their unique configurations, they have distinctive electronic properties, high Young's moduli, high tensile strength, ultrahigh hardness, good ductility, and low density, and may be potentially applied to a variety of needs.
Three-Dimensional Reflectance Traction Microscopy
Jones, Christopher A. R.; Groves, Nicholas Scott; Sun, Bo
2016-01-01
Cells in three-dimensional (3D) environments exhibit very different biochemical and biophysical phenotypes compared to the behavior of cells in two-dimensional (2D) environments. As an important biomechanical measurement, 2D traction force microscopy can not be directly extended into 3D cases. In order to quantitatively characterize the contraction field, we have developed 3D reflectance traction microscopy which combines confocal reflection imaging and partial volume correlation postprocessing. We have measured the deformation field of collagen gel under controlled mechanical stress. We have also characterized the deformation field generated by invasive breast cancer cells of different morphologies in 3D collagen matrix. In contrast to employ dispersed tracing particles or fluorescently-tagged matrix proteins, our methods provide a label-free, computationally effective strategy to study the cell mechanics in native 3D extracellular matrix. PMID:27304456
Three-dimensional image contrast using biospeckle
NASA Astrophysics Data System (ADS)
Godinho, Robson Pierangeli; Braga, Roberto A., Jr.
2010-09-01
The biospeckle laser (BSL) has been applied in many areas of knowledge and a variety of approaches has been presented to address the best results in biological and non-biological samples, in fast or slow activities, or else in defined flow of materials or in random activities. The methodologies accounted in the literature consider the apparatus used in the image assembling and the way the collected data is processed. The image processing steps presents in turn a variety of procedures with first or second order statistics analysis, and as well with different sizes of data collected. One way to access the biospeckle in defined flow, such as in capillary blood flow in alive animals, was the adoption of the image contrast technique which uses only one image from the illuminated sample. That approach presents some problems related to the resolution of the image, which is reduced during the image contrast processing. In order to help the visualization of the low resolution image formed by the contrast technique, this work presents the three-dimensional procedure as a reliable alternative to enhance the final image. The work based on a parallel processing, with the generation of a virtual map of amplitudes, and maintaining the quasi-online characteristic of the contrast technique. Therefore, it was possible to generate in the same display the observed material, the image contrast result and in addiction the three-dimensional image with adjustable options of rotation. The platform also offers to the user the possibility to access the 3D image offline.
Three Dimensional Structures in the Atmospheres of Cool Stars
NASA Technical Reports Server (NTRS)
Walter, Frederick M.
1997-01-01
This grant has supported my GHRS-related activities since 1990. This included both instrumental calibration activities and independent scientific research using the Goddard High Resolution Spectrograph on the Hubble Space Telescope. The activities under this grant are essentially complete. Publications to date which have resulted in whole or in part from this grant are included.
Scalar decay in a three-dimensional chaotic flow.
Ngan, K; Vanneste, J
2011-05-01
The decay of a passive scalar in a three-dimensional chaotic flow is studied using high-resolution numerical simulations. The (volume-preserving) flow considered is a three-dimensional extension of the randomized alternating sine flow employed extensively in studies of mixing in two dimensions. It is used to show that theoretical predictions for two-dimensional flows with small diffusivity carry over to three dimensions even though the stretching properties differ significantly. The variance decay rate, scalar field structure, and time evolution of statistical moments confirm that there are two distinct regimes of scalar decay: a locally controlled regime, which applies when the domain size is comparable to the characteristic length scale of the velocity field, and a globally controlled regime, which applies when the domain is larger. Asymptotic predictions for the variance decay rate in both regimes show excellent agreement with the numerical results. Consideration of both the forward flow and its time reverse makes it possible to compare the scalar evolution in flows with one or two expanding directions; simulations confirm the theoretical prediction that the decay rate of the scalar is the same in both flows, despite the very different scalar field structures.
Initial three-dimensional low-thrust trajectory design
NASA Astrophysics Data System (ADS)
Taheri, Ehsan; Abdelkhalik, Ossama
2016-02-01
This paper presents a method for rapid generation of three-dimensional low-thrust trajectories that utilizes Fourier series for shaping the position vector. The generated trajectories are feasible with respect to the given thrust acceleration constraints. An objective function is defined representing the overall mission cost, i.e. minimum ΔV . Four missions from Earth to Mars, the near Earth asteroid 1989ML, comet Tempel 1 and asteroid Dionysus are considered for assessing the performance of the algorithm. The selected missions present a range of various difficulties with different levels of thrust acceleration constraints. The Fourier series technique is flexible in generating various shapes rather than using one global shape. The proposed method is capable of rapid generation of sub-optimal feasible trajectories that are totally different from and comparable to the solutions of the state-of-the-art three-dimensional shape-based methods. This feature is quite favorable at the preliminary stages of low-thrust mission designs where various trajectory alternatives are required. The results also show that the obtained trajectories can be used as initial guesses for high fidelity optimal control tools.
NASA Astrophysics Data System (ADS)
Kaspi, Y.; Showman, A. P.
2014-04-01
The recent discoveries of terrestrial exoplanets and super Earths extending over a broad range of orbital and physical parameters, suggests that these planets will span a wide range of climatic regimes. Characterization of the atmospheres of warm super Earths has already begun and will be extended to smaller and more distant planets over the coming decade. The habitability of these worlds may be strongly affected by their three-dimensional atmospheric circulation regimes, since the global climate feedbacks that control the inner and outer edges of the habitable zone-including transitions to Snowballlike states and runaway-greenhouse feedbacks-depend on the equator-to-pole temperature differences, pattern of relative humidity, and other aspects of the dynamics. Here, using an idealized moist atmospheric general circulation model (GCM) including a hydrological cycle, we study the dynamical principles governing the atmospheric dynamics on such planets. We show how the planetary rotation rate, planetary mass, surface gravity, heat flux from a parent star and atmospheric mass affect the atmospheric circulation and temperature distribution on such planets. We elucidate the possible climatic regimes and diagnose the mechanisms controlling the formation of atmospheric jet streams, Hadley cells, and the equator-to-pole temperature differences. Finally, we discuss the implications for understanding how the atmospheric circulation influences the global-scale climate feedbacks that control the width of the habitable zone.
Three-dimensional Atmospheric Circulation and Climate of Terrestrial Exoplanets and Super Earths
NASA Astrophysics Data System (ADS)
Kaspi, Yohai; Showman, A. P.
2012-10-01
The recent discovery of super Earths and terrestrial exoplanets extending over a broad region of orbital and physical parameter space suggests that these planets will span a wide range of climatic regimes. Characterization of the atmospheres of warm super Earths has already begun and will be extended to smaller and more distant planets over the coming decade. The habitability of these worlds may be strongly affected by their three-dimensional atmospheric circulation regimes, since the global climate feedbacks that control the inner and outer edges of the habitable zone--including transitions to Snowball-like states and runaway-greenhouse feedbacks--depend on the equator-to-pole temperature differences, pattern of relative humidity, and other aspects of the dynamics. Here, using an idealized moist atmospheric general circulation model (GCM) including a hydrological cycle, we study the dynamical principles governing the atmospheric dynamics on such planets. In this presentation we will review how the planetary rotation rate, planetary mass, heat flux from a parent star and atmospheric mass affect the atmospheric circulation and temperature distribution on such planets. We will elucidate the possible climatic regimes and diagnose the mechanisms controlling the formation of atmospheric jet streams, Hadley cells, and the equator-to-pole temperature differences. Finally, we will discuss the implications for understanding how the atmospheric circulation influences the global-scale climate feedbacks that control the width of the habitable zone.
Three-Dimensional Polybenzobisoxazoles and Polybenzobisthiazoles
NASA Technical Reports Server (NTRS)
Bray, M.; Harruna, I. I.; Bota, K. B.
1997-01-01
Due to the poor compressive strength properties of high performance liquid crystalline polymers such as polybenzobisoxazoles (PBOs) and polybenzobisthiazoles (PBTs), we have prepared homopolymers and copolymers with PBO and PBT pendant groups on a central star-like unit, 2.7-diamino-9,9'-bis(4-aminophenyl)fluorene, in order to improve upon their compressive strength properties. The fluorene moiety was prepared by the reaction of 2,7-dinitro-9-fluorene with aniline and aniline hydrochloride, followed by reduction with palladium on carbon. The central star-like unit was characterized by FTIR, FTNMR, and elemental analysis. The PBO and PBT pendant groups were synthesized by the polycondensation of 4,6-diaminoresorcinol dihydrochloride with terephthaloyl chloride and 2,5-diamino-1,4-benzendithiol dihydrochloride with terephthaloyl chloride in poly(phosphoric acid), respectively. The resulting linear polymers containing the dicarboxylic end groups were attached to the central star-like unit by refluxing with 2,7-diamino-9,9'-bis(4-aminophenyl) fluorene to give the star-like polymers. The star-like PBO and PBT were soluble in methanesulfonic acid. Further characterization of the polymers is ongoing.
Primary and Secondary Three Dimensional Microbatteries
NASA Astrophysics Data System (ADS)
Cirigliano, Nicolas
Today's MEMS devices are limited more so by the batteries that supply their power than the fabrication methods used to build them. Thick battery electrodes are capable of providing adequate energy, but long and tortuous diffusion pathways lead to low power capabilities. On the other hand, thin film batteries can operate at significant current densities but require large surface areas to supply practical energy. This dilemma can be solved by either developing new high capacity materials or by engineering new battery designs that decouple power and energy. Three dimensional batteries redesign traditional configurations to create nonplanar interfaces between battery components. This can be done by introducing hierarchical structures into the electrode shape. Designs such as these provide a maximum surface area over which chemical reactions can occur. Furthermore, by maintaining small feature sizes, ion diffusion and electronic transport distances can remain minimal. Manipulating these properties ensures fast kinetics that are required for high power situations. Energy density is maximized by layering material in the vertical direction, thus ensuring a minimal footprint area. Three dimensional carbon electrodes are fabricated using basic MEMS techniques. A silicon mold is anisotropically etched to produce channels of a predetermined diameter. The channels are then filled using an infiltration technique with electrode slurry. Once dried, the mold is attached to a current collector and etched using a XeF2 process. Electrodes of varying feature sizes have been fabricated using this method with aspect ratios ranging from 3.5:1 to 7:1. 3D carbon electrodes are shown to obtain capacities over 8 mAh/cm2 at 0.1 mA/cm2, or nearly 700% higher than planar carbon electrodes. When assembled with a planar cathode, the battery cell produced an average discharge capacity of 40 J/cm 2 at a current density of 0.2 mA/cm2. This places the energy density values slightly less than thick
Nanoscale three-dimensional single particle tracking
NASA Astrophysics Data System (ADS)
Dupont, Aurélie; Lamb, Don C.
2011-11-01
Single particle tracking (SPT) in biological systems is a quickly growing field. Many new technologies are being developed providing new tracking capabilities, which also lead to higher demands and expectations for SPT. Following a single biomolecule as it performs its function provides quantitative mechanistic information that cannot be obtained in classical ensemble methods. From the 3D trajectory, information is available over the diffusional behavior of the particle and precise position information can also be used to elucidate interactions of the tracked particle with its surroundings. Thus, three-dimensional (3D) SPT is a very valuable tool for investigating cellular processes. This review presents recent progress in 3D SPT, from image-based techniques toward more sophisticated feedback approaches. We focus mainly on the feedback technique known as orbital tracking. We present here a modified version of the original orbital tracking in which the intensities from two z-planes are simultaneously measured allowing a concomitant wide-field imaging. The system can track single particles with a precision down to 5 nm in the x-y plane and 7 nm in the axial direction. The capabilities of the system are demonstrated using single virus tracing to follow the infection pathway of Prototype Foamy Virus in living cells.Single particle tracking (SPT) in biological systems is a quickly growing field. Many new technologies are being developed providing new tracking capabilities, which also lead to higher demands and expectations for SPT. Following a single biomolecule as it performs its function provides quantitative mechanistic information that cannot be obtained in classical ensemble methods. From the 3D trajectory, information is available over the diffusional behavior of the particle and precise position information can also be used to elucidate interactions of the tracked particle with its surroundings. Thus, three-dimensional (3D) SPT is a very valuable tool for
The Three-dimensional Structure of the Eta Carinae Homunculus
NASA Technical Reports Server (NTRS)
Steffen, W.; Teodoro, M.; Madura, T.I.; Groh, J.H.; Gull, T.R.; Mehner, A.; Corcoran, M.F.; Damineli, A.; Hamaguchi, K.
2014-01-01
We investigate, using the modeling code SHAPE, the three-dimensional structure of the bipolar Homunculus nebula surrounding Eta Carinae as mapped by new ESO VLT/X-Shooter observations of the H2 (lambda) = 2.12125 micrometers emission line. Our results reveal for the first time important deviations from the axisymmetric bipolar morphology: 1) circumpolar trenches in each lobe positioned point-symmetrically from the center and 2) offplanar protrusions in the equatorial region from each lobe at longitudinal (approximately 55 degrees) and latitudinal (10 degrees to 20 degrees) distances from the projected apastron direction of the binary orbit. The angular distance between the protrusions (approximately 110 degrees) is similar to the angular extent of each polar trench (approximately 130 degrees) and nearly equal to the opening angle of the wind-wind collision cavity (approximately 110 degrees). As in previous studies, we confirm a hole near the centre of each polar lobe and no detectable near-IR H2 emission from the thin optical skirt seen prominently in visible imagery. We conclude that the interaction between the outflows and/or radiation from the central binary stars and their orientation in space has had, and possibly still has, a strong influence on the Homunculus. This implies that prevailing theoretical models of the Homunculus are incomplete as most assume a single star origin that produces an axisymmetric nebula.We discuss how the newly found features might be related to the Homunculus ejection, the central binary and the interacting stellar winds.
Three-dimensional simulations of fracture dissolution
NASA Astrophysics Data System (ADS)
Starchenko, Vitaliy; Marra, Cameron J.; Ladd, Anthony J. C.
2016-09-01
Numerical studies of fracture dissolution are frequently based on two-dimensional models, where the fracture geometry is represented by an aperture field h(x,y). However, it is known that such models can break down when the spatial variations in aperture are rapid or large in amplitude; for example, in a rough fracture or when instabilities in the dissolution front develop into pronounced channels (or wormholes). Here we report a finite-volume implementation of a three-dimensional reactive transport model using the OpenFOAM® toolkit. Extensions to the OpenFOAM source code have been developed which displace and then relax the mesh in response to variations in the surface concentration; up to 100-fold increases in fracture aperture are possible without remeshing. Our code has simulated field-scale fractures with physical dimensions of about 10 m. We report simulations of smooth fractures, with small, well-controlled perturbations in fracture aperture introduced at the inlet. This allows for systematic convergence studies and for detailed comparisons with results from a two-dimensional model. Initially, the fracture aperture develops similarly in both models, but as local inhomogeneities develop the results start to diverge. We investigate numerically the onset of instabilities in the dissolution of fractures with small random variations in the initial aperture field. Our results show that elliptical cross sections, which are characteristic of karstic conduits, can develop very rapidly, on time scales of 10-20 years in calcite rocks.
Tip selection in three-dimensional dendrites
NASA Astrophysics Data System (ADS)
Foster, M. R.; Tanveer, S.
2004-11-01
Dendrites are well-known to have a fully three-dimensional structure, often with four equally-spaced fins emanating from the steady parabolic tip, the pattern for which has now a good theoretical foundation.(McFadden, Coriell & Sekerka, J. Crys. Growth) 208 (2000) The four fins are of course related to four-fold crystalline anisotropy of quite small magnitude. We follow Tanveer(Tanveer, S. Phys. Rev. A) 40 (1989) in carefully exploring the matching of the inner solution in the neighborhood of the singularity nearest the real line to the small-surface-energy regular perturbation expansion, in order to obtain the (selected) tip radius and the amplitude of the fin. We consider the case for which the anisotropy parameter, α, is much larger than a dimensionless capillary length to the 4/7 power. We confirm what was already found in a slightly different parameter range(Ben Amar & Brener, Phys. Rev. Lett.) 71 (1993)--that the inner equation is essentially that of the two-dimensional case, with azimuthally-dependent parameters. We compare our results with those of Ben Amar & Brener.
Three dimensional characterization and archiving system
Sebastian, R.L.; Clark, R.; Gallman, P.
1996-04-01
The Three Dimensional Characterization and Archiving System (3D-ICAS) is being developed as a remote system to perform rapid in situ analysis of hazardous organics and radionuclide contamination on structural materials. Coleman Research and its subcontractors, Thermedics Detection, Inc. (TD) and the University of Idaho (UI) are in the second phase of a three phase program to develop 3D-ICAS to support Decontamination and Decommissioning (D and D) operations. Accurate physical characterization of surfaces and the radioactive and organic is a critical D and D task. Surface characterization includes identification of potentially dangerous inorganic materials, such as asbestos and transite. Real-time remotely operable characterization instrumentation will significantly advance the analysis capabilities beyond those currently employed. Chemical analysis is a primary area where the characterization process will be improved. The 3D-ICAS system robotically conveys a multisensor probe near the surfaces to be inspected. The sensor position and orientation are monitored and controlled using coherent laser radar (CLR) tracking. The CLR also provides 3D facility maps which establish a 3D world view within which the robotic sensor system can operate.
Three-dimensional context regulation of metastasis
Erler, Janine T.; Weaver, Valerie M.
2009-01-01
Tumor progression ensues within a three-dimensional microenvironment that consists of cellular and non-cellular components. The extracellular matrix (ECM) and hypoxia are two non-cellular components that potently influence metastasis. ECM remodeling and collagen cross-linking stiffen the tissue stroma to promote transformation, tumor growth, motility and invasion, enhance cancer cell survival, enable metastatic dissemination, and facilitate the establishment of tumor cells at distant sites. Matrix degradation can additionally promote malignant progression and metastasis. Tumor hypoxia is functionally linked to altered stromal-epithelial interactions. Hypoxia additionally induces the expression of pro-migratory, survival and invasion genes, and up-regulates expression of ECM components and modifying enzymes, to enhance tumor progression and metastasis. Synergistic interactions between matrix remodeling and tumor hypoxia influence common mechanisms that maximize tumor progression and cooperate to drive metastasis. Thus, clarifying the molecular pathways by which ECM remodeling and tumor hypoxia intersect to promote tumor progression should identify novel therapeutic targets. PMID:18814043
Magnetophotonic response of three-dimensional opals.
Caicedo, José Manuel; Pascu, Oana; López-García, Martín; Canalejas, Víctor; Blanco, Alvaro; López, Cefe; Fontcuberta, Josep; Roig, Anna; Herranz, Gervasi
2011-04-26
Three-dimensional magnetophotonic crystals (3D-MPCs) are being postulated as appropriate platforms to tailor the magneto-optical spectral response of magnetic materials and to incorporate this functionality in a new generation of optical devices. By infiltrating self-assembled inverse opal structures with monodisperse nickel nanoparticles we have fabricated 3D-MPCs that show a sizable enhancement of the magneto-optical signal at frequencies around the stop-band edges of the photonic crystals. We have established a proper methodology to disentangle the intrinsic magneto-optical spectra from the nonmagnetic optical activity of the 3D-MPCs. The results of the optical and magneto-optical characterization are consistent with a homogeneous magnetic infiltration of the opal structure that gives rise to both a red-shift of the optical bandgap and a modification of the magneto-optical spectral response due to photonic bandgap effects. The results of our investigation demonstrate the potential of 3D-MPCs fabricated following the approach outlined here and offer opportunities to adapt the magneto-optical spectral response at optical frequencies by appropriate design of the opal structure or magnetic field strength.
A three-dimensional human walking model
NASA Astrophysics Data System (ADS)
Yang, Q. S.; Qin, J. W.; Law, S. S.
2015-11-01
A three-dimensional human bipedal walking model with compliant legs is presented in this paper. The legs are modeled with time-variant dampers, and the model is able to characterize the gait pattern of an individual using a minimal set of parameters. Feedback control, for both the forward and lateral movements, is implemented to regulate the walking performance of the pedestrian. The model provides an improvement over classic invert pendulum models. Numerical studies were undertaken to investigate the effects of leg stiffness and attack angle. Simulation results show that when walking at a given speed, increasing the leg stiffness with a constant attack angle results in a longer step length, a higher step frequency, a faster walking speed and an increase in both the peak vertical and lateral ground reaction forces. Increasing the attack angle with a constant leg stiffness results in a higher step frequency, a decrease in the step length, an increase in the total energy of the system and a decrease in both the peak vertical and lateral ground reaction forces.
Three-dimensional planning in craniomaxillofacial surgery
Rubio-Palau, Josep; Prieto-Gundin, Alejandra; Cazalla, Asteria Albert; Serrano, Miguel Bejarano; Fructuoso, Gemma Garcia; Ferrandis, Francisco Parri; Baró, Alejandro Rivera
2016-01-01
Introduction: Three-dimensional (3D) planning in oral and maxillofacial surgery has become a standard in the planification of a variety of conditions such as dental implants and orthognathic surgery. By using custom-made cutting and positioning guides, the virtual surgery is exported to the operating room, increasing precision and improving results. Materials and Methods: We present our experience in the treatment of craniofacial deformities with 3D planning. Software to plan the different procedures has been selected for each case, depending on the procedure (Nobel Clinician, Kodak 3DS, Simplant O&O, Dolphin 3D, Timeus, Mimics and 3-Matic). The treatment protocol is exposed step by step from virtual planning, design, and printing of the cutting and positioning guides to patients’ outcomes. Conclusions: 3D planning reduces the surgical time and allows predicting possible difficulties and complications. On the other hand, it increases preoperative planning time and needs a learning curve. The only drawback is the cost of the procedure. At present, the additional preoperative work can be justified because of surgical time reduction and more predictable results. In the future, the cost and time investment will be reduced. 3D planning is here to stay. It is already a fact in craniofacial surgery and the investment is completely justified by the risk reduction and precise results. PMID:28299272
Three-dimensional Diffusive Strip Method
NASA Astrophysics Data System (ADS)
Martinez-Ruiz, Daniel; Meunier, Patrice; Duchemin, Laurent; Villermaux, Emmanuel
2016-11-01
The Diffusive Strip Method (DSM) is a near-exact numerical method developed for mixing computations at large Péclet number in two-dimensions. The method consists in following stretched material lines to compute a-posteriori the resulting scalar field is extended here to three-dimensional flows, following surfaces. We describe its 3D peculiarities, and show how it applies to a simple Taylor-Couette configuration with non-rotating boundary conditions at the top end, bottom and outer cylinder. This flow produces an elaborate, although controlled, steady 3D flow which relies on the Ekman pumping arising from the rotation of the inner cylinder is both studied experimentally, and numerically modeled. A recurrent two-cells structure appears formed by stream tubes shaped as nested tori. A scalar blob in the flow experiences a Lagrangian oscillating dynamics with stretchings and compressions, driving the mixing process, and yielding both rapidly-mixed and nearly pure-diffusive regions. A triangulated-surface method is developed to calculate the blob elongation and scalar concentration PDFs through a single variable computation along the advected blob surface, capturing the rich evolution observed in the experiments.
Three-dimensional Printing in the Intestine.
Wengerter, Brian C; Emre, Gulus; Park, Jea Young; Geibel, John
2016-08-01
Intestinal transplantation remains a life-saving option for patients with severe intestinal failure. With the advent of advanced tissue engineering techniques, great strides have been made toward manufacturing replacement tissues and organs, including the intestine, which aim to avoid transplant-related complications. The current paradigm is to seed a biocompatible support material (scaffold) with a desired cell population to generate viable replacement tissue. Although this technique has now been extended by the three-dimensional (3D) printing of geometrically complex scaffolds, the overall approach is hindered by relatively slow turnover and negative effects of residual scaffold material, which affects final clinical outcome. Methods recently developed for scaffold-free 3D bioprinting may overcome such obstacles and should allow for rapid manufacture and deployment of "bioprinted organs." Much work remains before 3D bioprinted tissues can enter clinical use. In this brief review we examine the present state and future perspectives of this nascent technology before full clinical implementation.
Three-dimensional landing zone ladar
NASA Astrophysics Data System (ADS)
Savage, James; Goodrich, Shawn; Burns, H. N.
2016-05-01
Three-Dimensional Landing Zone (3D-LZ) refers to a series of Air Force Research Laboratory (AFRL) programs to develop high-resolution, imaging ladar to address helicopter approach and landing in degraded visual environments with emphasis on brownout; cable warning and obstacle avoidance; and controlled flight into terrain. Initial efforts adapted ladar systems built for munition seekers, and success led to a the 3D-LZ Joint Capability Technology Demonstration (JCTD) , a 27-month program to develop and demonstrate a ladar subsystem that could be housed with the AN/AAQ-29 FLIR turret flown on US Air Force Combat Search and Rescue (CSAR) HH-60G Pave Hawk helicopters. Following the JCTD flight demonstration, further development focused on reducing size, weight, and power while continuing to refine the real-time geo-referencing, dust rejection, obstacle and cable avoidance, and Helicopter Terrain Awareness and Warning (HTAWS) capability demonstrated under the JCTD. This paper summarizes significant ladar technology development milestones to date, individual LADAR technologies within 3D-LZ, and results of the flight testing.
PLOT3D- DRAWING THREE DIMENSIONAL SURFACES
NASA Technical Reports Server (NTRS)
Canright, R. B.
1994-01-01
PLOT3D is a package of programs to draw three-dimensional surfaces of the form z = f(x,y). The function f and the boundary values for x and y are the input to PLOT3D. The surface thus defined may be drawn after arbitrary rotations. However, it is designed to draw only functions in rectangular coordinates expressed explicitly in the above form. It cannot, for example, draw a sphere. Output is by off-line incremental plotter or online microfilm recorder. This package, unlike other packages, will plot any function of the form z = f(x,y) and portrays continuous and bounded functions of two independent variables. With curve fitting; however, it can draw experimental data and pictures which cannot be expressed in the above form. The method used is division into a uniform rectangular grid of the given x and y ranges. The values of the supplied function at the grid points (x, y) are calculated and stored; this defines the surface. The surface is portrayed by connecting successive (y,z) points with straight-line segments for each x value on the grid and, in turn, connecting successive (x,z) points for each fixed y value on the grid. These lines are then projected by parallel projection onto the fixed yz-plane for plotting. This program has been implemented on the IBM 360/67 with on-line CDC microfilm recorder.
Three-dimensional laser velocimeter simultaneity detector
NASA Technical Reports Server (NTRS)
Brown, James L. (Inventor)
1990-01-01
A three-dimensional laser Doppler velocimeter has laser optics for a first channel positioned to create a probe volume in space, and laser optics and for second and third channels, respectively, positioned to create entirely overlapping probe volumes in space. The probe volumes and overlap partially in space. The photodetector is positioned to receive light scattered by a particle present in the probe volume, while photodetectors and are positioned to receive light scattered by a particle present in the probe volume. The photodetector for the first channel is directly connected to provide a first channel analog signal to frequency measuring circuits. The first channel is therefore a primary channel for the system. Photodetectors and are respectively connected through a second channel analog signal attenuator to frequency measuring circuits and through a third channel analog signal attenuator to frequency measuring circuits. The second and third channels are secondary channels, with the second and third channels analog signal attenuators and controlled by the first channel measurement burst signal on line. The second and third channels analog signal attenuators and attenuate the second and third channels analog signals only when the measurement burst signal is false.
Three dimensional, multi-chip module
Bernhardt, A.F.; Petersen, R.W.
1992-12-31
The present invention relates to integrated circuit packaging technology, and particularly to three dimensional packages involving high density stacks of integrated circuits. A plurality of multi-chip modules are stacked and bonded around the perimeter by sold-bump bonds to adjacent modules on, for instance, three sides of the perimeter. The fourth side can be used for coolant distribution, for more interconnect structures, or other features, depending on particular design considerations of the chip set. The multi-chip modules comprise a circuit board, having a planarized interconnect structure formed on a first major surface, and integrated circuit chips bonded to the planarized interconnect surface. Around the periphery of each circuit board, long, narrow ``dummy chips`` are bonded to the finished circuit board to form a perimeter wall. The wall is higher than any of the chips on the circuit board, so that the flat back surface of the board above will only touch the perimeter wall. Module-to-module interconnect is laser-patterned on the sides of the boards and over the perimeter wall in the same way and at the same time that chip to board interconnect may be laser-patterned.
Three dimensional characterization and archiving system
Sebastian, R.L.; Clark, R.; Gallman, P.
1995-10-01
The Three Dimensional Characterization and Archiving System (3D-ICAS) is being developed as a remote system to perform rapid in situ analysis of hazardous organics and radionuclide contamination on structural materials. Coleman Research and its subcontractors, Thermedics Detection, Inc. (TD) and the University of Idaho (UI) are in the second phase of a three phase program to develop 3D-ICAS to support Decontamination and Decommissioning (D&D) operations. Accurate physical characterization of surfaces and the radioactive and organic is a critical D&D task. Surface characterization includes identification of potentially dangerous inorganic materials, such as asbestos and transite. The 3D-ICAS system robotically conveys a multisensor probe near the surface to be inspected. The sensor position and orientation are monitored and controlled by Coherent laser radar (CLR) tracking. The ICAS fills the need for high speed automated organic analysis by means of gas chromatography-mass spectrometry sensors, and also by radionuclide sensors which combines alpha, beta, and gamma counting.
FRET Imaging in Three-dimensional Hydrogels
Taboas, Juan M.
2016-01-01
Imaging of Förster resonance energy transfer (FRET) is a powerful tool for examining cell biology in real-time. Studies utilizing FRET commonly employ two-dimensional (2D) culture, which does not mimic the three-dimensional (3D) cellular microenvironment. A method to perform quenched emission FRET imaging using conventional widefield epifluorescence microscopy of cells within a 3D hydrogel environment is presented. Here an analysis method for ratiometric FRET probes that yields linear ratios over the probe activation range is described. Measurement of intracellular cyclic adenosine monophosphate (cAMP) levels is demonstrated in chondrocytes under forskolin stimulation using a probe for EPAC1 activation (ICUE1) and the ability to detect differences in cAMP signaling dependent on hydrogel material type, herein a photocrosslinking hydrogel (PC-gel, polyethylene glycol dimethacrylate) and a thermoresponsive hydrogel (TR-gel). Compared with 2D FRET methods, this method requires little additional work. Laboratories already utilizing FRET imaging in 2D can easily adopt this method to perform cellular studies in a 3D microenvironment. It can further be applied to high throughput drug screening in engineered 3D microtissues. Additionally, it is compatible with other forms of FRET imaging, such as anisotropy measurement and fluorescence lifetime imaging (FLIM), and with advanced microscopy platforms using confocal, pulsed, or modulated illumination. PMID:27500354
Three-dimensional modelling of Venus photochemistry
NASA Astrophysics Data System (ADS)
Stolzenbach, Aurélien; Lefèvre, Franck; Lebonnois, Sébastien; Määttänen, Anni; Bekki, Slimane
2014-05-01
We have developed a new code of the Venus atmospheric chemistry based on our photochemical model already in use for Mars (e.g., Lefèvre et al., J. Geophys. Res., 2004). For Venus, the code also includes a parameterized treatment of cloud microphysics that computes the composition of sulphuric acid droplets and their number density based on a given droplet size distribution in altitude. We coupled this photochemical-microphysical package to the LMD general circulation model of Venus (Lebonnois et al., J. Geophys. Res., 2010) with a sedimentation module recently added. We will describe preliminary results obtained with this first three-dimensional model of the Venus photochemistry. The space and time distribution of key chemical species as well as the modelled clouds characteristics will be detailed and compared to observations performed from Venus Express and from the Earth (e.g. Knollenberg and Hunten, J. Geophys. Res., 1980 ; Wilquet et al., J. Geophys. Res., 2009 ; Sandor et al., Icarus, 2012).
Three-Dimensional Modelling of Venus Photochemistry
NASA Astrophysics Data System (ADS)
Stolzenbach, A.; Lefèvre, F.; Lebonnois, S.; Maattanen, A. E.; Bekki, S.
2015-12-01
We have developed a new code of the Venus atmospheric chemistry based on our photochemical model already in use for Mars (e.g., Lefèvre et al., J. Geophys. Res., 2004). For Venus, the code also includes a parameterized treatment of cloud microphysics that computes the composition of sulphuric acid droplets and their number density based on a given droplet size distribution in altitude and latitude. We coupled this photochemical-microphysical package to the LMD general circulation model of Venus (Lebonnois et al., J. Geophys. Res., 2010) with a sedimentation module that takes into account the parametrized droplet size distribution. We will describe the results obtained with this first three-dimensional model of the Venus photochemistry. The space and time distribution of key chemical species as well as the modelled clouds characteristics will be detailed and compared to observations performed from Venus Express and from the Earth (e.g. Knollenberg and Hunten, J. Geophys. Res., 1980 ; Wilquet et al., J. Geophys. Res., 2009 ; Sandor et al., Icarus, 2012 ; Mahieux et al., PSS, 2014 ; Marcq et al., 2015, PSS).
Three-dimensional modeling of tsunami waves
Mader, C.L.
1985-01-01
Two- and three-dimensional, time-dependent, nonlinear, incompressible, viscous flow calculations of realistic models of tsunami wave formation and run up have been performed using the Los Alamos-developed SOLA-3D code. The results of the SOLA calculations are compared with shallow-water, long-wave calculations for the same problems using the SWAN code. Tsunami wave formation by a continental slope subsidence has been examined using the two numerical models. The SOLA waves were slower than the SWAN waves and the interaction with the shoreline was more complicated for the SOLA waves. In the SOLA calculation, the first wave was generated by the cavity being filled along the shoreline close to the source of motion. The second wave was generated by the cavity being filled from the deep water end. The two waves interacted along the shoreline resulting in the second wave being the largest wave with a velocity greater than the first wave. The second wave overtook the first wave at later times and greater distances from the source. In the SWAN calculation, the second wave was smaller than the first wave. 6 refs.
Three-dimensional visualization for large models
NASA Astrophysics Data System (ADS)
Roth, Michael W.
2001-09-01
High-resolution (0.3-1 m) digital-elevation data is widely available from commercial sources. Whereas the production of two-dimensional (2D) mapping products from such data is standard practice, the visualization of such three-dimensional (3D) data has been problematic. The basis for this problem is the same as that for the large-model problem in computer graphics-- large amounts of geometry are difficult for current rendering algorithms and hardware. This paper describes a cost-effective solution to this problem that has two parts. First is the employment of the latest in cost-effective 3D chips and video boards that have recently emerged. The second part is the employment of quad-tree data structures for efficient data storage and retrieval during rendering. The result is the capability for real-time display of large (over tens of millions of samples) digital elevation models on modest PC-based systems. This paper shows several demonstrations of this approach using airborne lidar data. The implication of this work is a paradigm shift for geo-spatial information systems--3D data can now be as easy to use as 2D data.
Three Dimensional Characterization of the Mundrabilla Meteorite
NASA Technical Reports Server (NTRS)
Gillies, Donald C.; Engel, H. Peter; Carpenter, P. K.
2003-01-01
The differentiated meteorite, Mundrabilla, exhibits a rare structure of primary kamacite/taenite, and at least 25 volume % of sulfide (troilite and daubreelite). The structure has been investigated in three dimensions using the technique of gamma-ray computed tomography (CT) with a radioactive (60)Co isotope as the source of the flux. Using CT, a 50 kg slab with dimensions 12.6 x 8.2 x approx. 70 cm has been sectioned at 1 mm intervals over 50 cm length, and the three dimensional structure is at present being evaluated. These data revealed, in addition to the metallic and troilite-rich phases, the presence and distribution of graphite-rich cones (up to 5 cm long), and small (1-2 mm), low density particles. The graphite cones are readily visible on the surfaces of many of the sections of Mundrabilla, while the smaller phases have a density (determined from CT) of approximately 2.9 g/cc, and are assumed to be silicate inclusions. CT spatial resolution is not adequate to elucidate the shapes of these particles. One can only state that they show no directionality and are equiaxed.
Two and three dimensional magnetotelluric inversion
Booker, J.
1993-01-01
Electrical conductivity depends on properties such as the presence of ionic fluids in interconnected pores that are difficult to sense with other remote sensing techniques. Thus improved imaging of underground electrical structure has wide practical importance in exploring for groundwater, mineral and geothermal resources, and in assessing the diffusion of fluids in oil fields and waste sites. Because the electromagnetic inverse problem is fundamentally multi-dimensional, most imaging algorithms saturate available computer power long before they can deal with the complete data set. We have developed an algorithm to directly invert large multi-dimensional data sets that is orders of magnitude faster than competing methods. We have proven that a two-dimensional (2D) version of the algorithm is highly effective for real data and have made substantial progress towards a three-dimensional (3D) version. We are proposing to cure identified shortcomings and substantially expand the utility of the existing 2D program, overcome identified difficulties with extending our method to three-dimensions (3D) and embark on an investigation of related EM imaging techniques which may have the potential for even further increasing resolution.
Three-Dimensional Optical Coherence Tomography
NASA Technical Reports Server (NTRS)
Gutin, Mikhail; Wang, Xu-Ming; Gutin, Olga
2009-01-01
Three-dimensional (3D) optical coherence tomography (OCT) is an advanced method of noninvasive infrared imaging of tissues in depth. Heretofore, commercial OCT systems for 3D imaging have been designed principally for external ophthalmological examination. As explained below, such systems have been based on a one-dimensional OCT principle, and in the operation of such a system, 3D imaging is accomplished partly by means of a combination of electronic scanning along the optical (Z) axis and mechanical scanning along the two axes (X and Y) orthogonal to the optical axis. In 3D OCT, 3D imaging involves a form of electronic scanning (without mechanical scanning) along all three axes. Consequently, the need for mechanical adjustment is minimal and the mechanism used to position the OCT probe can be correspondingly more compact. A 3D OCT system also includes a probe of improved design and utilizes advanced signal- processing techniques. Improvements in performance over prior OCT systems include finer resolution, greater speed, and greater depth of field.
Globographic visualisation of three dimensional joint angles.
Baker, Richard
2011-07-07
Three different methods for describing three dimensional joint angles are commonly used in biomechanics. The joint coordinate system and Cardan/Euler angles are conceptually quite different but are known to represent the same underlying mathematics. More recently the globographic method has been suggested as an alternative and this has proved particularly attractive for the shoulder joint. All three methods can be implemented in a number of ways leading to a choice of angle definitions. Very recently Rab has demonstrated that the globographic method is equivalent to one implementation of the joint coordinate system. This paper presents a rigorous analysis of the three different methods and proves their mathematical equivalence. The well known sequence dependence of Cardan/Euler is presented as equivalent to configuration dependence of the joint coordinate system and orientation dependence of globographic angles. The precise definition of different angle sets can be easily visualised using the globographic method using analogues of longitude, latitude and surface bearings with which most users will already be familiar. The method implicitly requires one axis of the moving segment to be identified as its principal axis and this can be extremely useful in helping define the most appropriate angle set to describe the orientation of any particular joint. Using this technique different angle sets are considered to be most appropriate for different joints and examples of this for the hip, knee, ankle, pelvis and axial skeleton are outlined.
Three dimensional imaging with randomly distributed sensors.
DaneshPanah, Mehdi; Javidi, Bahram; Watson, Edward A
2008-04-28
As a promising three dimensional passive imaging modality, Integral Imaging (II) has been investigated widely within the research community. In virtually all of such investigations, there is an implicit assumption that the collection of elemental images lie on a simple geometric surface (e.g. flat, concave, etc), also known as pickup surface. In this paper, we present a generalized framework for 3D II with arbitrary pickup surface geometry and randomly distributed sensor configuration. In particular, we will study the case of Synthetic Aperture Integral Imaging (SAII) with random location of cameras in space, while all cameras have parallel optical axes but different distances from the 3D scene. We assume that the sensors are randomly distributed in 3D volume of pick up space. For 3D reconstruction, a finite number of sensors with known coordinates are randomly selected from within this volume. The mathematical framework for 3D scene reconstruction is developed based on an affine transform representation of imaging under geometrical optics regime. We demonstrate the feasibility of the methods proposed here by experimental results. To the best of our knowledge, this is the first report on 3D imaging using randomly distributed sensors.
Generation of three-dimensional medical thermograms.
Chan, F H; So, A T; Lam, F K
1996-01-01
To visualise non-invasively human organs in their true form and shape has intrigued mankind for centuries. Three-dimensional (3D) imaging is one recent development that has brought us closer to fulfilling the age-old quest of non-invasive visualisation so that diagnoses by doctors can be efficiently enhanced. Nowadays, 3D CT and MRI images have been very popular. Thermography is an important medical imaging technique that displays the temperature distribution on the surface of a human organ and it has been proved to be significant in offering a unique physiological reflection of pathology that may confirm or enhance the anatomic findings of other diagnostic imaging modalities. It is the only imaging modality that can evaluate pain whereas plain radiographs, CT and MRI, etc. can only depict structural anatomic abnormalities that may not always coincide with patients' clinical complaints. It is against this background that 3D thermograms have been developed. A set of comprehensive calibration procedures for the 3-camera system have been designed based on different models for the optical and infrared cameras. The accuracy of the results is high enough to produce 3D thermograms that can be used to correlate with the 3D images from other medical imaging modalities. One important achievement of the system is that the resultant 3D images are absolutely dimensioned and hence, it is particularly favourable for fully autonomous applications with robots. The system can also provide an overall picture of both the structural abnormalities and nervous responses of patients.
Three dimensional characterization and archiving system
Sebastian, R.L.; Clark, R.; Gallman, P.
1995-12-01
The Three Dimensional Characterization and Archiving System (3D-ICAS) is being developed as a remote system to perform rapid in situ analysis of hazardous organics and radionuclide contamination on structural materials. Coleman Research and its subcontractors, Thermedics Detection, Inc. (TD) and the University of Idaho (UI) are in the second phase of a three phase program to develop 3D-ICAS to support Decontamination and Decommissioning (D&D) operations. Accurate physical characterization of surfaces and the radioactive and organic is a critical D&D task. Surface characterization includes identification of potentially dangerous inorganic materials, such as asbestos and transite. Real-time remotely operable characterization instrumentation will significantly advance the analysis capabilities beyond those currently employed. Chemical analysis is a primary area where the characterization process will be improved. Chemical analysis plays a vital role throughout the process of decontamination. Before clean-up operations can begin the site must be characterized with respect to the type and concentration of contaminants, and detailed site mapping must clarify areas of both high and low risk. During remediation activities chemical analysis provides a means to measure progress and to adjust clean-up strategy. Once the clean-up process has been completed the results of chemical analysis will verify that the site is in compliance with federal and local regulations.
Three-dimensional charge coupled device
Conder, Alan D.; Young, Bruce K. F.
1999-01-01
A monolithic three dimensional charged coupled device (3D-CCD) which utilizes the entire bulk of the semiconductor for charge generation, storage, and transfer. The 3D-CCD provides a vast improvement of current CCD architectures that use only the surface of the semiconductor substrate. The 3D-CCD is capable of developing a strong E-field throughout the depth of the semiconductor by using deep (buried) parallel (bulk) electrodes in the substrate material. Using backside illumination, the 3D-CCD architecture enables a single device to image photon energies from the visible, to the ultra-violet and soft x-ray, and out to higher energy x-rays of 30 keV and beyond. The buried or bulk electrodes are electrically connected to the surface electrodes, and an E-field parallel to the surface is established with the pixel in which the bulk electrodes are located. This E-field attracts charge to the bulk electrodes independent of depth and confines it within the pixel in which it is generated. Charge diffusion is greatly reduced because the E-field is strong due to the proximity of the bulk electrodes.
Three-Dimensional Imaging of Viral Infections.
Risco, Cristina; de Castro, Isabel Fernández; Sanz-Sánchez, Laura; Narayan, Kedar; Grandinetti, Giovanna; Subramaniam, Sriram
2014-11-01
Three-dimensional (3D) imaging technologies are beginning to have significant impact in the field of virology, as they are helping us understand how viruses take control of cells. In this article we review several methodologies for 3D imaging of cells and show how these technologies are contributing to the study of viral infections and the characterization of specialized structures formed in virus-infected cells. We include 3D reconstruction by transmission electron microscopy (TEM) using serial sections, electron tomography, and focused ion beam scanning electron microscopy (FIB-SEM). We summarize from these methods selected contributions to our understanding of viral entry, replication, morphogenesis, egress and propagation, and changes in the spatial architecture of virus-infected cells. In combination with live-cell imaging, correlative microscopy, and new techniques for molecular mapping in situ, the availability of these methods for 3D imaging is expected to provide deeper insights into understanding the structural and dynamic aspects of viral infection.
Three-Dimensional Frame Buffers For Interactive Analysis Of Three-Dimensional Data
NASA Astrophysics Data System (ADS)
Hunter, Gregory M.
1986-02-01
Two-dimensional data such as photos, x-rays, various types of satellite images, sonar, radar, seismic plots, etc., in many cases must be analyzed using frame buffers for purposes of medical diagnoses, crop estimates, mineral exploration, and so forth. In many cases the same types of sensors used to gather such samples in two dimensions can gather 3D data for even more effective analysis. Just as 2D arrays of data can be analyzed using frame buffers, three-dimensional data can be analyzed using SOLIDS-BUFFER memories. Image processors deal with samples from two-dimensional arrays and are based on frame buffers. The SOLIDS PROCESSOR system deals with samples from a three-dimensional volume, or solid, and is based on a 3D frame buffer. This paper focuses upon the SOLIDS-BUFFER system as used in the INSIGHT SOLIDS-PROCESSOR system from Phoenix Data Systems.
NASA Astrophysics Data System (ADS)
Mathur, S.; Hekker, S.; Trampedach, R.; Ballot, J.; Kallinger, T.; Buzasi, D.; García, R. A.; Huber, D.; Jiménez, A.; Mosser, B.; Bedding, T. R.; Elsworth, Y.; Régulo, C.; Stello, D.; Chaplin, W. J.; De Ridder, J.; Hale, S. J.; Kinemuchi, K.; Kjeldsen, H.; Mullally, F.; Thompson, S. E.
2011-11-01
The granulation pattern that we observe on the surface of the Sun is due to hot plasma rising to the photosphere where it cools down and descends back into the interior at the edges of granules. This is the visible manifestation of convection taking place in the outer part of the solar convection zone. Because red giants have deeper convection zones than the Sun, we cannot a priori assume that their granulation is a scaled version of solar granulation. Until now, neither observations nor one-dimensional analytical convection models could put constraints on granulation in red giants. With asteroseismology, this study can now be performed. We analyze ~1000 red giants that have been observed by Kepler during 13 months. We fit the power spectra with Harvey-like profiles to retrieve the characteristics of the granulation (timescale τgran and power P gran). We search for a correlation between these parameters and the global acoustic-mode parameter (the position of maximum power, νmax) as well as with stellar parameters (mass, radius, surface gravity (log g), and effective temperature (T eff)). We show that τeffvpropν-0.89 max and P granvpropν-1.90 max, which is consistent with the theoretical predictions. We find that the granulation timescales of stars that belong to the red clump have similar values while the timescales of stars in the red giant branch are spread in a wider range. Finally, we show that realistic three-dimensional simulations of the surface convection in stars, spanning the (T eff, log g) range of our sample of red giants, match the Kepler observations well in terms of trends.
Mathur, S.; Hekker, S.; Trampedach, R.; Ballot, J.; Kallinger, T.; Buzasi, D.; Garcia, R. A.; Jimenez, A.; Regulo, C.; Mosser, B.; Elsworth, Y.; Chaplin, W. J.; Hale, S. J.; De Ridder, J.; Kinemuchi, K.; Mullally, F.
2011-11-10
The granulation pattern that we observe on the surface of the Sun is due to hot plasma rising to the photosphere where it cools down and descends back into the interior at the edges of granules. This is the visible manifestation of convection taking place in the outer part of the solar convection zone. Because red giants have deeper convection zones than the Sun, we cannot a priori assume that their granulation is a scaled version of solar granulation. Until now, neither observations nor one-dimensional analytical convection models could put constraints on granulation in red giants. With asteroseismology, this study can now be performed. We analyze {approx}1000 red giants that have been observed by Kepler during 13 months. We fit the power spectra with Harvey-like profiles to retrieve the characteristics of the granulation (timescale {tau}{sub gran} and power P{sub gran}). We search for a correlation between these parameters and the global acoustic-mode parameter (the position of maximum power, {nu}{sub max}) as well as with stellar parameters (mass, radius, surface gravity (log g), and effective temperature (T{sub eff})). We show that {tau}{sub eff}{proportional_to}{nu}{sup -0.89}{sub max} and P{sub gran}{proportional_to}{nu}{sup -1.90}{sub max}, which is consistent with the theoretical predictions. We find that the granulation timescales of stars that belong to the red clump have similar values while the timescales of stars in the red giant branch are spread in a wider range. Finally, we show that realistic three-dimensional simulations of the surface convection in stars, spanning the (T{sub eff}, log g) range of our sample of red giants, match the Kepler observations well in terms of trends.
Three dimensional CAD model of the Ignitor machine
NASA Astrophysics Data System (ADS)
Orlandi, S.; Zanaboni, P.; Macco, A.; Sioli, V.; Risso, E.
1998-11-01
defind The final, global product of all the structural and thermomechanical design activities is a complete three dimensional CAD (AutoCAD and Intergraph Design Review) model of the IGNITOR machine. With this powerful tool, any interface, modification, or upgrading of the machine design is managed as an integrated part of the general effort aimed at the construction of the Ignitor facility. ind The activities that are underway, to complete the design of the core of the experiment and that will be described, concern the following: ind - the cryogenic cooling system, ind - the radial press, the center post, the mechanical supports (legs) of the entire machine, ind - the inner mechanical supports of major components such as the plasma chamber and the outer poloidal field coils.
Three-dimensional kinematic reconnection of plasmoids with nulls
NASA Technical Reports Server (NTRS)
Lau, Yun-Tung; Finn, John M.
1992-01-01
The global nonlinear dynamics of magnetic field lines in plasmoids with a pair of nulls, where B = 0, is studied. The aim of this analysis is to describe the separatrix surfaces on which singularities can occur in ideal magnetohydrodynamics because of topological changes in the field. These separatrix surfaces should locate the boundary layers associated with 3D reconnection in the presence of resistivity or inertia. It is found that the field lines exhibit chaotic scattering with several properties in common with plasmoid models without nulls (in which one component of the magnetic field never changes sign). In particular, the singular surfaces can be fractal, implying complex current density structures down to the dissipation scale. These generic features are expected to exist in typical coronal magnetic geometries exhibiting three-dimensional reconnection and the formation of current sheets.
Three-Dimensional Numerical Modeling of Magnetohydrodynamic Augmented Propulsion Experiment
NASA Technical Reports Server (NTRS)
Turner, M. W.; Hawk, C. W.; Litchford, R. J.
2009-01-01
Over the past several years, NASA Marshall Space Flight Center has engaged in the design and development of an experimental research facility to investigate the use of diagonalized crossed-field magnetohydrodynamic (MHD) accelerators as a possible thrust augmentation device for thermal propulsion systems. In support of this effort, a three-dimensional numerical MHD model has been developed for the purpose of analyzing and optimizing accelerator performance and to aid in understanding critical underlying physical processes and nonideal effects. This Technical Memorandum fully summarizes model development efforts and presents the results of pretest performance optimization analyses. These results indicate that the MHD accelerator should utilize a 45deg diagonalization angle with the applied current evenly distributed over the first five inlet electrode pairs. When powered at 100 A, this configuration is expected to yield a 50% global efficiency with an 80% increase in axial velocity and a 50% increase in centerline total pressure.
On the Secondary Instability of Three-Dimensional Boundary Layers
NASA Astrophysics Data System (ADS)
Janke, Erik; Balakumar, Ponnampalam
One of the possible transition scenarios in three-dimensional boundary layers, the saturation of stationary crossflow vortices and their secondary instability to high-frequency disturbances, is studied using the Parabolized Stability Equations (PSE) and Floquet theory. Starting from nonlinear PSE solutions, we investigate the region where a purely stationary crossflow disturbance saturates for its secondary instability characteristics utilizing global and local eigenvalue solvers that are based on the Implicitly Restarted Arnoldi Method and a Newton-Raphson technique, respectively. Results are presented for swept Hiemenz flow and the DLR swept flat plate experiment. The main focuses of this study are on the existence of multiple roots in the eigenvalue spectrum that could explain experimental observations of time-dependent occurrences of an explosive growth of traveling disturbances, on the origin of high-frequency disturbances, as well as on gaining more information about threshold amplitudes of primary disturbances necessary for the growth of secondary disturbances.
Split Bregman's algorithm for three-dimensional mesh segmentation
NASA Astrophysics Data System (ADS)
Habiba, Nabi; Ali, Douik
2016-05-01
Variational methods have attracted a lot of attention in the literature, especially for image and mesh segmentation. The methods aim at minimizing the energy to optimize both edge and region detections. We propose a spectral mesh decomposition algorithm to obtain disjoint but meaningful regions of an input mesh. The related optimization problem is nonconvex, and it is very difficult to find a good approximation or global optimum, which represents a challenge in computer vision. We propose an alternating split Bregman algorithm for mesh segmentation, where we extended the image-dedicated model to a three-dimensional (3-D) mesh one. By applying our scheme to 3-D mesh segmentation, we obtain fast solvers that can outperform various conventional ones, such as graph-cut and primal dual methods. A consistent evaluation of the proposed method on various public domain 3-D databases for different metrics is elaborated, and a comparison with the state-of-the-art is performed.
Three dimensional direct numerical simulation of complex jet flows
NASA Astrophysics Data System (ADS)
Shin, Seungwon; Kahouadji, Lyes; Juric, Damir; Chergui, Jalel; Craster, Richard; Matar, Omar
2016-11-01
We present three-dimensional simulations of two types of very challenging jet flow configurations. The first consists of a liquid jet surrounded by a faster coaxial air flow and the second consists of a global rotational motion. These computations require a high spatial resolution and are performed with a newly developed high performance parallel code, called BLUE, for the simulation of two-phase, multi-physics and multi-scale incompressible flows, tested on up to 131072 threads with excellent scalability performance. The method for the treatment of the fluid interfaces uses a hybrid Front Tracking/Level Set technique that defines the interface both by a discontinuous density field as well as by a local triangular Lagrangian mesh. Coriolis forces are taken into account and solved via an exact time-integration method that ensures numerical accuracy and stability. EPSRC UK Programme Grant EP/K003976/1.
Three-dimensional ring current decay model
NASA Technical Reports Server (NTRS)
Fok, Mei-Ching; Moore, Thomas E.; Kozyra, Janet U.; Ho, George C.; Hamilton, Douglas C.
1995-01-01
This work is an extension of a previous ring current decay model. In the previous work, a two-dimensional kinetic model was constructed to study the temporal variations of the equatorially mirroring ring current ions, considering charge exchange and Coulomb drag losses along drift paths in a magnetic dipole field. In this work, particles with arbitrary pitch angle are considered. By bounce averaging the kinetic equation of the phase space density, information along magnetic field lines can be inferred from the equator. The three-dimensional model is used to simulate the recovery phase of a model great magnetic storm, similar to that which occurred in early February 1986. The initial distribution of ring current ions (at the minimum Dst) is extrapolated to all local times from AMPTE/CCE spacecraft observations on the dawnside and duskside of the inner magnetosphere spanning the L value range L = 2.25 to 6.75. Observations by AMPTE/CCE of ring current distributions over subsequent orbits during the storm recovery phase are compared to model outputs. In general, the calculated ion fluxes are consistent with observations, except for H(+) fluxes at tens of keV, which are always overestimated. A newly invented visualization idea, designated as a chromogram, is used to display the spatial and energy dependence of the ring current ion differential flux. Important features of storm time ring current, such as day-night asymmetry during injection and drift hole on the dayside at low energies (less than 10 keV), are manifested in the chromogram representation. The pitch angle distribution is well fit by the function, J(sub o)(1 + Ay(sup n)), where y is sine of the equatorial pitch angle. The evolution of the index n is a combined effect of charge exchange loss and particle drift. At low energies (less than 30 keV), both drift dispersion and charge exchange are important in determining n.
Remote Dynamic Three-Dimensional Scene Reconstruction
Yang, You; Liu, Qiong; Ji, Rongrong; Gao, Yue
2013-01-01
Remote dynamic three-dimensional (3D) scene reconstruction renders the motion structure of a 3D scene remotely by means of both the color video and the corresponding depth maps. It has shown a great potential for telepresence applications like remote monitoring and remote medical imaging. Under this circumstance, video-rate and high resolution are two crucial characteristics for building a good depth map, which however mutually contradict during the depth sensor capturing. Therefore, recent works prefer to only transmit the high-resolution color video to the terminal side, and subsequently the scene depth is reconstructed by estimating the motion vectors from the video, typically using the propagation based methods towards a video-rate depth reconstruction. However, in most of the remote transmission systems, only the compressed color video stream is available. As a result, color video restored from the streams has quality losses, and thus the extracted motion vectors are inaccurate for depth reconstruction. In this paper, we propose a precise and robust scheme for dynamic 3D scene reconstruction by using the compressed color video stream and their inaccurate motion vectors. Our method rectifies the inaccurate motion vectors by analyzing and compensating their quality losses, motion vector absence in spatial prediction, and dislocation in near-boundary region. This rectification ensures the depth maps can be compensated in both video-rate and high resolution at the terminal side towards reducing the system consumption on both the compression and transmission. Our experiments validate that the proposed scheme is robust for depth map and dynamic scene reconstruction on long propagation distance, even with high compression ratio, outperforming the benchmark approaches with at least 3.3950 dB quality gains for remote applications. PMID:23667417
Three-dimensional Spontaneous Magnetic Reconnection
NASA Astrophysics Data System (ADS)
Beresnyak, Andrey
2017-01-01
Magnetic reconnection is best known from observations of the Sun where it causes solar flares. Observations estimate the reconnection rate as a small, but non-negligible fraction of the Alfvén speed, so-called fast reconnection. Until recently, the prevailing pictures of reconnection were either of resistivity or plasma microscopic effects, which was contradictory to the observed rates. Alternative pictures were either of reconnection due to the stochasticity of magnetic field lines in turbulence or the tearing instability of the thin current sheet. In this paper we simulate long-term three-dimensional nonlinear evolution of a thin, planar current sheet subject to a fast oblique tearing instability using direct numerical simulations of resistive-viscous magnetohydrodynamics. The late-time evolution resembles generic turbulence with a ‑5/3 power spectrum and scale-dependent anisotropy, so we conclude that the tearing-driven reconnection becomes turbulent reconnection. The turbulence is local in scale, so microscopic diffusivity should not affect large-scale quantities. This is confirmed by convergence of the reconnection rate toward ∼ 0.015{v}{{A}} with increasing Lundquist number. In this spontaneous reconnection, with mean field and without driving, the dissipation rate per unit area also converges to ∼ 0.006ρ {v}{{A}}3, and the dimensionless constants 0.015 and 0.006 are governed only by self-driven nonlinear dynamics of the sheared magnetic field. Remarkably, this also means that a thin current sheet has a universal fluid resistance depending only on its length to width ratio and to {v}{{A}}/c.
Three-dimensional topological insulator based nanospaser
NASA Astrophysics Data System (ADS)
Paudel, Hari P.; Apalkov, Vadym; Stockman, Mark I.
2016-04-01
After the discovery of the spaser (surface plasmon amplification by stimulated emission of radiation), first proposed by Bergman and Stockman in 2003, it has become possible to deliver optical energy beyond the diffraction limit and generate an intense source of an optical field. The spaser is a nanoplasmonic counterpart of a laser. One of the major advantages of the spaser is its size: A spaser is a truly nanoscopic device whose size can be made smaller than the skin depth of a material to a size as small as the nonlocality radius (˜1 nm). Recently, an electrically pumped graphene based nanospaser has been proposed that operates in the midinfrared region and utilizes a nanopatch of graphene as a source of plasmons and a quantum-well cascade as its gain medium. Here we propose an optically pumped nanospaser based on three-dimensional topological insulator (3D TI) materials, such as Bi2Se3 , that operates at an energy close to the bulk band-gap energy ˜0.3 eV and uses the surface as a source for plasmons and its bulk as a gain medium. Population inversion is obtained in the bulk and the radiative energy of the exciton recombination is transferred to the surface plasmons of the same material to stimulate spasing action. This is truly a nanoscale spaser as it utilizes the same material for dual purposes. We show theoretically the possibility of achieving spasing with a 3D TI. As the spaser operates in the midinfrared spectral region, it can be a useful device for a number of applications, such as nanoscopy, nanolithography, nanospectroscopy, and semiclassical information processing.
[Three-dimensional reconstruction of heart valves].
Flachskampf, F A; Kühl, H; Franke, A; Frielingsdorf, J; Klues, H; Krebs, W; Hanrath, P
1995-08-01
The reconstruction of three-dimensional data sets from two-dimensional echocardiographic images offers several fundamental advantages: 1. more complete data than present in the few standard 2D-view; 2. off-line generation of any desired plane, cut, or perspective after the data set has been acquired; 3. access to quantitative parameters like surface areas (e.g., of valve leaflets or portions of leaflets), volumes, and others, without geometric assumptions. The mitral valve has been the focus of several studies using various techniques of reconstruction of transthoracic or transesophageal images. These studies have shown the mitral annulus to be a non-planar, "saddle-shaped" structure, with an average distance of highest to lowest points of 14 mm in normals. This recognition of mitral annular non-planarity has led to a more stringent echocardiographic definition of mitral valve prolapse. Further studies have shown systolic shrinkage of mitral annular area by about 30% and systolic apico-basal translation of the annulus by approximately 1 cm in normals. In patients with dilated cardiomyopathy, the annulus is flattened, and both cyclic change in annular area and apico-basal translation are significantly reduced. 3D-studies of the left ventricular outflow tract in hypertrophic obstructive cardiomyopathy allow measurement of outflow tract and leaflet surface areas and dynamic spatial visualization of systolic anterior motion of the anterior mitral leaflet. Automated techniques to reconstruct the full grey value data set from a high number of parallel or rotational transesophageal planes allow impressive visualization of normal and diseased mitral and aortic valves or valve prostheses, with special emphasis on generating "surgical" views and perspectives, which cannot be obtained by conventional tomographic imaging.(ABSTRACT TRUNCATED AT 250 WORDS)
Three-dimensional discrete-time Lotka-Volterra models with an application to industrial clusters
NASA Astrophysics Data System (ADS)
Bischi, G. I.; Tramontana, F.
2010-10-01
We consider a three-dimensional discrete dynamical system that describes an application to economics of a generalization of the Lotka-Volterra prey-predator model. The dynamic model proposed is used to describe the interactions among industrial clusters (or districts), following a suggestion given by [23]. After studying some local and global properties and bifurcations in bidimensional Lotka-Volterra maps, by numerical explorations we show how some of them can be extended to their three-dimensional counterparts, even if their analytic and geometric characterization becomes much more difficult and challenging. We also show a global bifurcation of the three-dimensional system that has no two-dimensional analogue. Besides the particular economic application considered, the study of the discrete version of Lotka-Volterra dynamical systems turns out to be a quite rich and interesting topic by itself, i.e. from a purely mathematical point of view.
Three-dimensional carbon nanotube based photovoltaics
NASA Astrophysics Data System (ADS)
Flicker, Jack
2011-12-01
Photovoltaic (PV) cells with a three dimensional (3D) morphology are an exciting new research thrust with promise to create cheaper, more efficient solar cells. This work introduces a new type of 3D PV device based on carbon nanotube (CNT) arrays. These arrays are paired with the thin film heterojunction, CdTe/CdS, to form a complete 3D carbon nanotube PV device (3DCNTPV). Marriage of a complicated 3D structure with production methods traditionally used for planar CdTe solar cell is challenging. This work examines the problems associated with processing these types of cells and systematically alters production methods of the semiconductor layers and electrodes to increase the short circuit current (Isc), eliminate parasitic shunts, and increase the open circuit voltage (Voc). The main benefit of 3D solar cell is the ability to utilize multiple photon interactions with the solar cell surface. The three dimensionality allows photons to interact multiple times with the photoactive material, which increases the absorption and the overall power output over what is possible with a two dimensional (2D) morphology. To quantify the increased power output arising from these multiple photon interactions, a new absorption efficiency term, eta3D, is introduced. The theoretical basis behind this new term and how it relates to the absorption efficiency of a planar cell, eta 2D, is derived. A unique model for the average number of multiple photon impingements, Gamma, is proposed based on three categories of 3D morphology: an infinite trench, an enclosed box, and an array of towers. The derivation of eta3D and Gamma for these 3D PV devices gives a complete picture of the enhanced power output over 2D cells based on CNT array height, pitch, radius, and shape. This theory is validated by monte carlo simulations and experiment. This new type of 3D PV devices has been shown to work experimentally. The first 3DCNTPV cells created posses Isc values of 0.085 to 17.872mA/cm2 and Voc values
Three-Dimensional Morphology of a Coronal Prominence Cavity
NASA Technical Reports Server (NTRS)
Gibson, S. E.; Kucera, T. A.; Rastawicki, D.; Dove, J.; deToma, G.; Hao, J.; Hill, S.; Hudson, H. S.; Marque, C.; McIntosh, P. S.; Rachmeler, L.; Reeves, K. K.; Schmieder, B.; Schmit, D. J.; Seaton, D. B.; Sterling, A. C.; Tripathi, D.; Williams, D. R.; Zhang, M.
2010-01-01
We present a three-dimensional density model of coronal prominence cavities, and a morphological fit that has been tightly constrained by a uniquely well-observed cavity. Observations were obtained as part of an International Heliophysical Year campaign by instruments from a variety of space- and ground-based observatories, spanning wavelengths from radio to soft-X-ray to integrated white light. From these data it is clear that the prominence cavity is the limb manifestation of a longitudinally-extended polar-crown filament channel, and that the cavity is a region of low density relative to the surrounding corona. As a first step towards quantifying density and temperature from campaign spectroscopic data, we establish the three-dimensional morphology of the cavity. This is critical for taking line-of-sight projection effects into account, since cavities are not localized in the plane of the sky and the corona is optically thin. We have augmented a global coronal streamer model to include a tunnel-like cavity with elliptical cross-section and a Gaussian variation of height along the tunnel length. We have developed a semi-automated routine that fits ellipses to cross-sections of the cavity as it rotates past the solar limb, and have applied it to Extreme Ultraviolet Imager (EUVI) observations from the two Solar Terrestrial Relations Observatory (STEREO) spacecraft. This defines the morphological parameters of our model, from which we reproduce forward-modeled cavity observables. We find that cavity morphology and orientation, in combination with the viewpoints of the observing spacecraft, explains the observed variation in cavity visibility for the east vs. west limbs
Symmetry enrichment in three-dimensional topological phases
NASA Astrophysics Data System (ADS)
Ning, Shang-Qiang; Liu, Zheng-Xin; Ye, Peng
2016-12-01
While two-dimensional symmetry-enriched topological phases (SETs ) have been studied intensively and systematically, three-dimensional ones are still open issues. We propose an algorithmic approach of imposing global symmetry Gs on gauge theories (denoted by GT) with gauge group Gg. The resulting symmetric gauge theories are dubbed "symmetry-enriched gauge theories" (SEG), which may be served as low-energy effective theories of three-dimensional symmetric topological quantum spin liquids. We focus on SEGs with gauge group Gg=ZN1×ZN2×⋯ and onsite unitary symmetry group Gs=ZK1×ZK2×⋯ or Gs=U (1 ) ×ZK 1×⋯ . Each SEG(Gg,Gs) is described in the path-integral formalism associated with certain symmetry assignment. From the path-integral expression, we propose how to physically diagnose the ground-state properties (i.e., SET orders) of SEGs in experiments of charge-loop braidings (patterns of symmetry fractionalization) and the mixed multiloop braidings among deconfined loop excitations and confined symmetry fluxes. From these symmetry-enriched properties, one can obtain the map from SEGs to SETs . By giving full dynamics to background gauge fields, SEGs may be eventually promoted to a set of new gauge theories (denoted by GT*). Based on their gauge groups, GT*s may be further regrouped into different classes, each of which is labeled by a gauge group Gg*. Finally, a web of gauge theories involving GT,SEG,SET, and GT* is achieved. We demonstrate the above symmetry-enrichment physics and the web of gauge theories through many concrete examples.
Realistic three-dimensional radiative transfer simulations of observed precipitation
NASA Astrophysics Data System (ADS)
Adams, I. S.; Bettenhausen, M. H.
2013-12-01
Remote sensing observations of precipitation typically utilize a number of instruments on various platforms. Ground validation campaigns incorporate ground-based and airborne measurements to characterize and study precipitating clouds, while the precipitation measurement constellation envisioned by the Global Precipitation Measurement (GPM) mission includes measurements from differing space-borne instruments. In addition to disparities such as frequency channel selection and bandwidth, measurement geometry and resolution differences between observing platforms result in inherent inconsistencies between data products. In order to harmonize measurements from multiple passive radiometers, a framework is required that addresses these differences. To accomplish this, we have implemented a flexible three-dimensional radiative transfer model. As its core, the radiative transfer model uses the Atmospheric Radiative Transfer Simulator (ARTS) version 2 to solve the radiative transfer equation in three dimensions using Monte Carlo integration. Gaseous absorption is computed with MonoRTM and formatted into look-up tables for rapid processing. Likewise, scattering properties are pre-computed using a number of publicly available codes, such as T-Matrix and DDSCAT. If necessary, a melting layer model can be applied to the input profiles. Gaussian antenna beams estimate the spatial resolutions of the passive measurements, and realistic bandpass characteristics can be included to properly account for the spectral response of the simulated instrument. This work presents three-dimensional simulations of WindSat brightness temperatures for an oceanic rain event sampled by the Tropical Rainfall Measuring Mission (TRMM) satellite. The 2B-31 combined Precipitation Radar / TRMM Microwave Imager (TMI) retrievals provide profiles that are the input to the radiative transfer model. TMI brightness temperatures are also simulated. Comparisons between monochromatic, pencil beam simulations and
Numerical investigations in three-dimensional internal flows
NASA Technical Reports Server (NTRS)
Rose, William C.
1991-01-01
The present study is a preliminary investigation into the behavior of the flow within a 28 degree total geometric turning angle hypothetical Mach 10 inlet as calculated with the full three-dimensional Navier-Stokes equations. Comparison between the two-dimensional and three-dimensional solutions have been made. The overall compression is not significantly different between the two-dimensional and center plane three dimensional solutions. Approximately one-half to two-thirds of the inlet flow at the exit of the inlet behave nominally two-dimensionally. On the other hand, flow field non-uniformities in the three-dimensional solution indicate the potential significance of the sidewall boundary layer flows ingested into the inlet. The tailoring of the geometry at the inlet shoulder and on the cowl obtained in the two-dimensional parametric design study have also proved to be effective at controlling the boundary layer behavior in the three-dimensional code. The three-dimensional inlet solution remained started indicating that the two-dimensional design had a sufficient margin to allow for three-dimensional flow field effects. Although confidence is being gained in the use of SCRAM3D (three-dimensional full Navier-Stokes code) as applied to similar flow fields, the actual effects of the three-dimensional flow fields associated with sidewalls and wind tunnel installations can require verification with ground-based experiments.
Three-Dimensional Gear Crack Propagation Studied
NASA Technical Reports Server (NTRS)
Lewicki, David G.
1999-01-01
Gears used in current helicopters and turboprops are designed for light weight, high margins of safety, and high reliability. However, unexpected gear failures may occur even with adequate tooth design. To design an extremely safe system, the designer must ask and address the question, "What happens when a failure occurs?" With gear-tooth bending fatigue, tooth or rim fractures may occur. A crack that propagates through a rim will be catastrophic, leading to disengagement of the rotor or propeller, loss of an aircraft, and possible fatalities. This failure mode should be avoided. A crack that propagates through a tooth may or may not be catastrophic, depending on the design and operating conditions. Also, early warning of this failure mode may be possible because of advances in modern diagnostic systems. One concept proposed to address bending fatigue fracture from a safety aspect is a splittooth gear design. The prime objective of this design would be to control crack propagation in a desired direction such that at least half of the tooth would remain operational should a bending failure occur. A study at the NASA Lewis Research Center analytically validated the crack-propagation failsafe characteristics of a split-tooth gear. It used a specially developed three-dimensional crack analysis program that was based on boundary element modeling and principles of linear elastic fracture mechanics. Crack shapes as well as the crack-propagation life were predicted on the basis of the calculated stress intensity factors, mixed-mode crack-propagation trajectory theories, and fatigue crack-growth theories. The preceding figures show the effect of the location of initial cracks on crack propagation. Initial cracks in the fillet of the teeth produced stress intensity factors of greater magnitude (and thus, greater crack growth rates) than those in the root or groove areas of the teeth. Crack growth was simulated in a case study to evaluate crack-propagation paths. Tooth
Advanced Three-Dimensional Display System
NASA Technical Reports Server (NTRS)
Geng, Jason
2005-01-01
A desktop-scale, computer-controlled display system, initially developed for NASA and now known as the VolumeViewer(TradeMark), generates three-dimensional (3D) images of 3D objects in a display volume. This system differs fundamentally from stereoscopic and holographic display systems: The images generated by this system are truly 3D in that they can be viewed from almost any angle, without the aid of special eyeglasses. It is possible to walk around the system while gazing at its display volume to see a displayed object from a changing perspective, and multiple observers standing at different positions around the display can view the object simultaneously from their individual perspectives, as though the displayed object were a real 3D object. At the time of writing this article, only partial information on the design and principle of operation of the system was available. It is known that the system includes a high-speed, silicon-backplane, ferroelectric-liquid-crystal spatial light modulator (SLM), multiple high-power lasers for projecting images in multiple colors, a rotating helix that serves as a moving screen for displaying voxels [volume cells or volume elements, in analogy to pixels (picture cells or picture elements) in two-dimensional (2D) images], and a host computer. The rotating helix and its motor drive are the only moving parts. Under control by the host computer, a stream of 2D image patterns is generated on the SLM and projected through optics onto the surface of the rotating helix. The system utilizes a parallel pixel/voxel-addressing scheme: All the pixels of the 2D pattern on the SLM are addressed simultaneously by laser beams. This parallel addressing scheme overcomes the difficulty of achieving both high resolution and a high frame rate in a raster scanning or serial addressing scheme. It has been reported that the structure of the system is simple and easy to build, that the optical design and alignment are not difficult, and that the
Three dimensional Visualization of Jupiter's Equatorial Region
NASA Technical Reports Server (NTRS)
1997-01-01
Frames from a three dimensional visualization of Jupiter's equatorial region. The images used cover an area of 34,000 kilometers by 11,000 kilometers (about 21,100 by 6,800 miles) near an equatorial 'hotspot' similar to the site where the probe from NASA's Galileo spacecraft entered Jupiter's atmosphere on December 7th, 1995. These features are holes in the bright, reflective, equatorial cloud layer where warmer thermal emission from Jupiter's deep atmosphere can pass through. The circulation patterns observed here along with the composition measurements from the Galileo Probe suggest that dry air may be converging and sinking over these regions, maintaining their cloud-free appearance. The bright clouds to the right of the hotspot as well as the other bright features may be examples of upwelling of moist air and condensation.
This frame is a view to the southeast, from between the cloud layers and over the north center of the region. The tall white clouds in the lower cloud deck are probably much like large terrestrial thunderclouds. They may be regions where atmospheric water powers vertical convection over large horizontal distances.
Galileo is the first spacecraft to image Jupiter in near-infrared light (which is invisible to the human eye) using three filters at 727, 756, and 889 nanometers (nm). Because light at these three wavelengths is absorbed at different altitudes by atmospheric methane, a comparison of the resulting images reveals information about the heights of clouds in Jupiter's atmosphere. This information can be visualized by rendering cloud surfaces with the appropriate height variations.
The visualization reduces Jupiter's true cloud structure to two layers. The height of a high haze layer is assumed to be proportional to the reflectivity of Jupiter at 889 nm. The height of a lower tropospheric cloud is assumed to be proportional to the reflectivity at 727 nm divided by that at 756 nm. This model is overly simplistic, but is based on
Three dimensional Visualization of Jupiter's Equatorial Region
NASA Technical Reports Server (NTRS)
1997-01-01
Frames from a three dimensional visualization of Jupiter's equatorial region. The images used cover an area of 34,000 kilometers by 11,000 kilometers (about 21,100 by 6,800 miles) near an equatorial 'hotspot' similar to the site where the probe from NASA's Galileo spacecraft entered Jupiter's atmosphere on December 7th, 1995. These features are holes in the bright, reflective, equatorial cloud layer where warmer thermal emission from Jupiter's deep atmosphere can pass through. The circulation patterns observed here along with the composition measurements from the Galileo Probe suggest that dry air may be converging and sinking over these regions, maintaining their cloud-free appearance. The bright clouds to the right of the hotspot as well as the other bright features may be examples of upwelling of moist air and condensation.
This frame is a view to the northeast, from between the cloud layers and above the streaks in the lower cloud leading towards the hotspot. The upper haze layer has some features that match the lower cloud, such as the bright streak in the foreground of the frame. These are probably thick clouds that span several tens of vertical kilometers.
Galileo is the first spacecraft to image Jupiter in near-infrared light (which is invisible to the human eye) using three filters at 727, 756, and 889 nanometers (nm). Because light at these three wavelengths is absorbed at different altitudes by atmospheric methane, a comparison of the resulting images reveals information about the heights of clouds in Jupiter's atmosphere. This information can be visualized by rendering cloud surfaces with the appropriate height variations.
The visualization reduces Jupiter's true cloud structure to two layers. The height of a high haze layer is assumed to be proportional to the reflectivity of Jupiter at 889 nm. The height of a lower tropospheric cloud is assumed to be proportional to the reflectivity at 727 nm divided by that at 756 nm. This model is overly
Three dimensional Visualization of Jupiter's Equatorial Region
NASA Technical Reports Server (NTRS)
1997-01-01
Frames from a three dimensional visualization of Jupiter's equatorial region. The images used cover an area of 34,000 kilometers by 11,000 kilometers (about 21,100 by 6,800 miles) near an equatorial 'hotspot' similar to the site where the probe from NASA's Galileo spacecraft entered Jupiter's atmosphere on December 7th, 1995. These features are holes in the bright, reflective, equatorial cloud layer where warmer thermal emission from Jupiter's deep atmosphere can pass through. The circulation patterns observed here along with the composition measurements from the Galileo Probe suggest that dry air may be converging and sinking over these regions, maintaining their cloud-free appearance. The bright clouds to the right of the hotspot as well as the other bright features may be examples of upwelling of moist air and condensation.
This frame is a view to the west, from between the cloud layers and over the patchy white clouds to the east of the hotspot. This is probably an area where moist convection is occurring over large horizontal distances, similar to the atmosphere over the equatorial ocean on Earth. The clouds are high and thick, and are observed to change rapidly over short time scales.
Galileo is the first spacecraft to image Jupiter in near-infrared light (which is invisible to the human eye) using three filters at 727, 756, and 889 nanometers (nm). Because light at these three wavelengths is absorbed at different altitudes by atmospheric methane, a comparison of the resulting images reveals information about the heights of clouds in Jupiter's atmosphere. This information can be visualized by rendering cloud surfaces with the appropriate height variations.
The visualization reduces Jupiter's true cloud structure to two layers. The height of a high haze layer is assumed to be proportional to the reflectivity of Jupiter at 889 nm. The height of a lower tropospheric cloud is assumed to be proportional to the reflectivity at 727 nm divided by that at 756
Three dimensional Visualization of Jupiter's Equatorial Region
NASA Technical Reports Server (NTRS)
1997-01-01
Frames from a three dimensional visualization of Jupiter's equatorial region. The images used cover an area of 34,000 kilometers by 11,000 kilometers (about 21,100 by 6,800 miles) near an equatorial 'hotspot' similar to the site where the probe from NASA's Galileo spacecraft entered Jupiter's atmosphere on December 7th, 1995. These features are holes in the bright, reflective, equatorial cloud layer where warmer thermal emission from Jupiter's deep atmosphere can pass through. The circulation patterns observed here along with the composition measurements from the Galileo Probe suggest that dry air may be converging and sinking over these regions, maintaining their cloud-free appearance. The bright clouds to the right of the hotspot as well as the other bright features may be examples of upwelling of moist air and condensation.
This frame is a view from the southwest looking northeast, from an altitude just above the high haze layer. The streaks in the lower cloud leading towards the hotspot are visible. The upper haze layer is mostly flat, with notable small peaks that can be matched with features in the lower cloud. In reality, these areas may represent a continuous vertical cloud column.
Galileo is the first spacecraft to image Jupiter in near-infrared light (which is invisible to the human eye) using three filters at 727, 756, and 889 nanometers (nm). Because light at these three wavelengths is absorbed at different altitudes by atmospheric methane, a comparison of the resulting images reveals information about the heights of clouds in Jupiter's atmosphere. This information can be visualized by rendering cloud surfaces with the appropriate height variations.
The visualization reduces Jupiter's true cloud structure to two layers. The height of a high haze layer is assumed to be proportional to the reflectivity of Jupiter at 889 nm. The height of a lower tropospheric cloud is assumed to be proportional to the reflectivity at 727 nm divided by that at 756
Three dimensional Visualization of Jupiter's Equatorial Region
NASA Technical Reports Server (NTRS)
1997-01-01
Frames from a three dimensional visualization of Jupiter's equatorial region. The images used cover an area of 34,000 kilometers by 11,000 kilometers (about 21,100 by 6,800 miles) near an equatorial 'hotspot' similar to the site where the probe from NASA's Galileo spacecraft entered Jupiter's atmosphere on December 7th, 1995. These features are holes in the bright, reflective, equatorial cloud layer where warmer thermal emission from Jupiter's deep atmosphere can pass through. The circulation patterns observed here along with the composition measurements from the Galileo Probe suggest that dry air may be converging and sinking over these regions, maintaining their cloud-free appearance. The bright clouds to the right of the hotspot as well as the other bright features may be examples of upwelling of moist air and condensation.
This frame is a view to the northeast, from between the cloud layers and above the streaks in the lower cloud leading towards the hotspot. The hotspot is clearly visible as a deep blue feature. The cloud streaks end near the hotspot, consistent with the idea that clouds traveling along these streak lines descend and evaporate as they approach the hotspot. The upper haze layer is slightly bowed upwards above the hotspot.
Galileo is the first spacecraft to image Jupiter in near-infrared light (which is invisible to the human eye) using three filters at 727, 756, and 889 nanometers (nm). Because light at these three wavelengths is absorbed at different altitudes by atmospheric methane, a comparison of the resulting images reveals information about the heights of clouds in Jupiter's atmosphere. This information can be visualized by rendering cloud surfaces with the appropriate height variations.
The visualization reduces Jupiter's true cloud structure to two layers. The height of a high haze layer is assumed to be proportional to the reflectivity of Jupiter at 889 nm. The height of a lower tropospheric cloud is assumed to be proportional
Three dimensional Visualization of Jupiter's Equatorial Region
NASA Technical Reports Server (NTRS)
1997-01-01
Frames from a three dimensional visualization of Jupiter's equatorial region. The images used cover an area of 34,000 kilometers by 11,000 kilometers (about 21,100 by 6,800 miles) near an equatorial 'hotspot' similar to the site where the probe from NASA's Galileo spacecraft entered Jupiter's atmosphere on December 7th, 1995. These features are holes in the bright, reflective, equatorial cloud layer where warmer thermal emission from Jupiter's deep atmosphere can pass through. The circulation patterns observed here along with the composition measurements from the Galileo Probe suggest that dry air may be converging and sinking over these regions, maintaining their cloud-free appearance. The bright clouds to the right of the hotspot as well as the other bright features may be examples of upwelling of moist air and condensation.
This frame is a view from above and to the south of the visualized area, showing the entire model. The entire region is overlain by a thin, transparent haze. In places the haze is high and thick, especially to the east (to the right of) the hotspot.
Galileo is the first spacecraft to image Jupiter in near-infrared light (which is invisible to the human eye) using three filters at 727, 756, and 889 nanometers (nm). Because light at these three wavelengths is absorbed at different altitudes by atmospheric methane, a comparison of the resulting images reveals information about the heights of clouds in Jupiter's atmosphere. This information can be visualized by rendering cloud surfaces with the appropriate height variations.
The visualization reduces Jupiter's true cloud structure to two layers. The height of a high haze layer is assumed to be proportional to the reflectivity of Jupiter at 889 nm. The height of a lower tropospheric cloud is assumed to be proportional to the reflectivity at 727 nm divided by that at 756 nm. This model is overly simplistic, but is based on more sophisticated studies of Jupiter's cloud structure. The upper
The three-dimensional structure of the Eta Carinae Homunculus
NASA Astrophysics Data System (ADS)
Steffen, W.; Teodoro, M.; Madura, T. I.; Groh, J. H.; Gull, T. R.; Mehner, A.; Corcoran, M. F.; Damineli, A.; Hamaguchi, K.
2014-08-01
We investigate, using the modelling code SHAPE, the three-dimensional structure of the bipolar Homunculus nebula surrounding Eta Carinae as mapped by new ESO Very Large Telescope/X-Shooter observations of the H2 λ = 2.121 25 μm emission line. Our results reveal for the first time important deviations from the axisymmetric bipolar morphology: (1) circumpolar trenches in each lobe positioned point symmetrically from the centre and (2) off-planar protrusions in the equatorial region from each lobe at longitudinal (˜55°) and latitudinal (10°-20°) distances from the projected apastron direction of the binary orbit. The angular distance between the protrusions (˜110°) is similar to the angular extent of each polar trench (˜130°) and nearly equal to the opening angle of the wind-wind collision cavity (˜110°). As in previous studies, we confirm a hole near the centre of each polar lobe and no detectable near-IR H2 emission from the thin optical skirt seen prominently in visible imagery. We conclude that the interaction between the outflows and/or radiation from the central binary stars and their orientation in space has had, and possibly still has, a strong influence on the Homunculus. This implies that prevailing theoretical models of the Homunculus are incomplete as most assume a single-star origin that produces an axisymmetric nebula. We discuss how the newly found features might be related to the Homunculus ejection, the central binary, and the interacting stellar winds.
Three-dimensional parallel vortex rings in Bose-Einstein condensates
Crasovan, Lucian-Cornel; Perez-Garcia, Victor M.; Danaila, Ionut; Mihalache, Dumitru; Torner, Lluis
2004-09-01
We construct three-dimensional structures of topological defects hosted in trapped wave fields, in the form of vortex stars, vortex cages, parallel vortex lines, perpendicular vortex rings, and parallel vortex rings, and we show that the latter exist as robust stationary, collective states of nonrotating Bose-Einstein condensates. We discuss the stability properties of excited states containing several parallel vortex rings hosted by the condensate, including their dynamical and structural stability.
Pathogen Propagation in Cultured Three-Dimensional Tissue Mass
NASA Technical Reports Server (NTRS)
Goodwin, Thomas J. (Inventor); Spaulding, Glenn F. (Inventor); Wolf, David A. (Inventor)
2000-01-01
A process for propagating a pathogen in a three-dimensional tissue mass cultured at microgravity conditions in a culture vessel containing culture media and a culture matrix is provided. The three-dimensional tissue mass is inoculated with a pathogen and pathogen replication in the cells of the tissue mass achieved.
Three-dimensional imaging of the myocardium with isotopes
NASA Technical Reports Server (NTRS)
Budinger, T. F.
1975-01-01
Three methods of imaging the three-dimensional distribution of isotopes in the myocardium are discussed. Three-dimensional imaging was examined using multiple Anger-camera views. Longitudinal tomographic images with compensation for blurring were studied. Transverse-section reconstruction using coincidence detection of annihilation gammas from positron emitting isotopes was investigated.
Pathogen propagation in cultured three-dimensional tissue mass
NASA Technical Reports Server (NTRS)
Goodwin, Thomas J. (Inventor); Spaulding, Glenn F. (Inventor); Wolf, David A. (Inventor)
2000-01-01
A process for propagating a pathogen in a three-dimensional tissue mass cultured at microgravity conditions in a culture vessel containing culture media and a culture matrix is provided. The three-dimensional tissue mass is inoculated with a pathogen and pathogen replication in the cells of the tissue mass achieved.
Computer-Generated, Three-Dimensional Character Animation.
ERIC Educational Resources Information Center
Van Baerle, Susan Lynn
This master's thesis begins by discussing the differences between 3-D computer animation of solid three-dimensional, or monolithic, objects, and the animation of characters, i.e., collections of movable parts with soft pliable surfaces. Principles from two-dimensional character animation that can be transferred to three-dimensional character…
Scanning holographic microscopy of three-dimensional fluorescent specimens
Indebetouw, Guy; Zhong, Wenwei
2006-01-01
We demonstrate experimentally the three-dimensional reconstructions of fluorescent biological specimens using scanning holographic microscopy. Three-dimensional reconstructions with transverse resolution below about 1 μm of transmission and fluorescence emission images are presented and analyzed. The limitations of the method are discussed. PMID:16783434
Using three-dimensional spacetime diagrams in special relativity
NASA Astrophysics Data System (ADS)
Dray, Tevian
2013-08-01
We provide three examples of the use of geometric reasoning with three-dimensional spacetime diagrams, rather than algebraic manipulations using three-dimensional Lorentz transformations, to analyze problems in special relativity. The examples are the "rising manhole" paradox, the "moving spotlight" problem, and Einstein's light-clock derivation of time dilation.
Sierra Stars Observatory Network: An Accessible Global Network
NASA Astrophysics Data System (ADS)
Williams, Richard; Beshore, Edward
2011-03-01
The Sierra Stars Observatory Network (SSON) is a unique partnership among professional observatories that provides its users with affordable high-quality calibrated image data. SSON comprises observatories in the Northern and Southern Hemisphere and is in the process of expanding to a truly global network capable of covering the entire sky 24 hours a day in the near future. The goal of SSON is to serve the needs of science-based projects and programs. Colleges, universities, institutions, and individuals use SSON for their education and research projects. The mission of SSON is to promote and expand the use of its facilities among the thousands of colleges and schools worldwide that do not have access to professional-quality automated observatory systems to use for astronomy education and research. With appropriate leadership and guidance educators can use SSON to help teach astronomy and do meaningful scientific projects. The relatively small cost of using SSON for this type of work makes it affordable and accessible for educators to start using immediately. Remote observatory services like SSON need to evolve to better support education and research initiatives of colleges, institutions and individual investigators. To meet these needs, SSON is developing a sophisticated interactive scheduling system to integrate among the nodes of the observatory network. This will enable more dynamic observations, including immediate priority interrupts, acquiring moving objects using ephemeris data, and more.
A comparison of two- and three-dimensional imaging
NASA Astrophysics Data System (ADS)
Hall, Ernest; Rosselot, Donald; Aull, Mark; Balapa, Manohar
2006-10-01
Three dimensional visual recognition and measurement are important in many machine vision applications. In some cases, a stationary camera base is used and a three-dimensional model will permit the measurement of depth information from a scene. One important special case is stereo vision for human visualization or measurements. In cases in which the camera base is also in motion, a seven dimensional model may be used. Such is the case for navigation of an autonomous mobile robot. The purpose of this paper is to provide a computational view and introduction of three methods to three-dimensional vision. Models are presented for each situation and example computations and images are presented. The significance of this work is that it shows that various methods based on three-dimensional vision may be used for solving two and three dimensional vision problems. We hope this work will be slightly iconoclastic but also inspirational by encouraging further research in optical engineering.
Radiative transfer for a three-dimensional raining cloud
NASA Technical Reports Server (NTRS)
Haferman, J. L.; Krajewski, W. F.; Smith, T. F.; Sanchez, A.
1993-01-01
Satellite-sensor-based microwave brightness temperatures for a three-dimensional raining cloud over a reflecting surface are computed by using a radiative transfer model based on the discrete-ordinates solution procedure. The three-dimensional model applied to a plane layer is validated by comparison with results from a one-dimensional model that is available in the literature. Results examining the effects of cloud height, rainfall rate, surface reflectance, rainfall footprint area, and satellite viewing position on one- and three-dimensional brightness temperature calculations are reported. The numerical experiments indicate that, under certain conditions, three-dimensional effects are significant in the analysis of satellite-sensor-based rainfall retrieval algorithms. The results point to the need to consider carefully three-dimensional effects as well as surface reflectance effects when interpreting satellite-measured radiation data.
Virtual three-dimensional blackboard: three-dimensional finger tracking with a single camera
NASA Astrophysics Data System (ADS)
Wu, Andrew; Hassan-Shafique, Khurram; Shah, Mubarak; da Vitoria Lobo, N.
2004-01-01
We present a method for three-dimensional (3D) tracking of a human finger from a monocular sequence of images. To recover the third dimension from the two-dimensional images, we use the fact that the motion of the human arm is highly constrained owing to the dependencies between elbow and forearm and the physical constraints on joint angles. We use these anthropometric constraints to derive a 3D trajectory of a gesticulating arm. The system is fully automated and does not require human intervention. The system presented can be used as a visualization tool, as a user-input interface, or as part of some gesture-analysis system in which 3D information is important.
Leadership and organizational ethics: the three dimensional African perspectives.
Mathooko, Jude Mutuku
2013-01-01
This paper addresses the past, present and future aspects of African leadership and organizational ethics that have, are and will be key for any organization to sustain its systems and structures. Organizational ethics revolves around written and/or unwritten guidelines, ethical values, principles, rules and standards, that are drawn from the harmonious coexistence with the biosphere and it is how these elements are applied that dictates the style of leadership and the ethical thinking of the leaders. Africa has a wide range of complexities which are compounded by, inter alia, tribal divisiveness, selfish leadership, wealth inequality, and massive unemployment. Africans tend to draw their leadership and ethical practices and reflections from the events in the environment with which they have interacted for many years. However, in order to fully address and understand the African perspective in leadership and organizational ethics, a broad comprehension of the African diverse and complex landscape is needed through unravelling of the three dimensional existence of the people. African ethics, developed over time, unifies organizations and leadership since it is part of life and is practised, sub-consciously or unconsciously, by the people as they transform from one practice to the other, and during intergenerational transitions. Globalization, liberalization, technological changes and advancement, and market changes are rapidly transforming the environment in which organizations operate. In such a situation, an effective and true leader cannot be rigid but should be flexible, with the ability to use different leadership styles whenever the situation calls for it. Only those leaders with a three-dimensional perspective live inspiring lives, live with a cause and adopt organizational ethics and leadership styles that will stand the test of time. Despite Africa being the cradle of humankind, leadership and organizational ethics is still in its infancy and wanting, even
Leadership and organizational ethics: the three dimensional African perspectives
2013-01-01
This paper addresses the past, present and future aspects of African leadership and organizational ethics that have, are and will be key for any organization to sustain its systems and structures. Organizational ethics revolves around written and/or unwritten guidelines, ethical values, principles, rules and standards, that are drawn from the harmonious coexistence with the biosphere and it is how these elements are applied that dictates the style of leadership and the ethical thinking of the leaders. Africa has a wide range of complexities which are compounded by, inter alia, tribal divisiveness, selfish leadership, wealth inequality, and massive unemployment. Africans tend to draw their leadership and ethical practices and reflections from the events in the environment with which they have interacted for many years. However, in order to fully address and understand the African perspective in leadership and organizational ethics, a broad comprehension of the African diverse and complex landscape is needed through unravelling of the three dimensional existence of the people. African ethics, developed over time, unifies organizations and leadership since it is part of life and is practised, sub-consciously or unconsciously, by the people as they transform from one practice to the other, and during intergenerational transitions. Globalization, liberalization, technological changes and advancement, and market changes are rapidly transforming the environment in which organizations operate. In such a situation, an effective and true leader cannot be rigid but should be flexible, with the ability to use different leadership styles whenever the situation calls for it. Only those leaders with a three-dimensional perspective live inspiring lives, live with a cause and adopt organizational ethics and leadership styles that will stand the test of time. Despite Africa being the cradle of humankind, leadership and organizational ethics is still in its infancy and wanting, even
The three dimensional current system during substorms
NASA Astrophysics Data System (ADS)
Gjerloev, Jesper; Hoffman, Robert
2013-04-01
We present results from a comprehensive statistical study of the ionospheric current system and it's coupling to the magnetosphere during classical bulge type substorms. We identified 116 substorms and determined the global ionospheric current system before and during the substorm using the SuperMAG initiative and global auroral images obtained by the Polar VIS Earth camera. The westward electrojet (WEJ) is centered around 65 / 72 deg magnetic latitude post-midnight / pre-midnight. Thus, we find a distinct latitudinal shift between the locations of the westward electrojet at these local times. The spatiotemporal behavior of the WEJ differs at these two local times. Attempting to explain this significant finding we propose two possible simple current systems. 1) The classical substorm current wedge, which is a single 3D current system. The distinct poleward kink and the different spatiotemporal behavior, however, present considerable complications for this solution. 2) A new 3D current system that consists of 2 wedge type systems: the classical substorm current wedge in the pre-midnight region and another current wedge in the post-midnight region. The latter maps to the inner magnetosphere. To support the empirical modeling we performed Biot and Savart integrations to simulate the ground perturbations. We present results of the statistical study, show typical events, results from the simulations, and discuss the implications for our understanding of the 3D current system associated with substorms.
Digital Moon: A three-dimensional framework for lunar modeling
NASA Astrophysics Data System (ADS)
Paige, D. A.; Elphic, R. C.; Foote, E. J.; Meeker, S. R.; Siegler, M. A.; Vasavada, A. R.
2009-12-01
The Moon has a complex three-dimensional shape with significant large-scale and small-scale topographic relief. The Moon’s topography largely controls the distribution of incident solar radiation, as well as the scattered solar and infrared radiation fields. Topography also affects the Moon’s interaction with the space environment, its magnetic field, and the propagation of seismic waves. As more extensive and detailed lunar datasets become available, there is an increasing need to interpret and compare them with the results of physical models in a fully three-dimensional context. We have developed a three-dimensional framework for lunar modeling we call the Digital Moon. The goal of this work is to enable high fidelity physical modeling and visualization of the Moon in a parallel computing environment. The surface of the Moon is described by a continuous triangular mesh of arbitrary shape and spatial scale. For regions of limited geographic extent, it is convenient to employ meshes on a rectilinear grid. However for global-scale modeling, we employ a continuous geodesic gridding scheme (Teanby, 2008). Each element in the mesh surface is allowed to have a unique set of physical properties. Photon and particle interactions between mesh elements are modeled using efficient ray tracing algorithms. Heat, mass, photon and particle transfer within each mesh element are modeled in one dimension. Each compute node is assigned a portion of the mesh and collective interactions between elements are handled through network interfaces. We have used the model to calculate lunar surface and subsurface temperatures that can be compared directly with radiometric temperatures measured by the Diviner Lunar Radiometer Experiment on the Lunar Reconnaissance Orbiter. The model includes realistic surface photometric functions based on goniometric measurements of lunar soil samples (Foote and Paige, 2009), and one-dimensional thermal models based on lunar remote sensing and Apollo
NASA Astrophysics Data System (ADS)
Abe, Makito; Umemura, Masayuki; Hasegawa, Kenji
2016-12-01
We explore the possibility of the formation of globular clusters (GCs) under ultraviolet (UV) background radiation. One-dimensional spherical symmetric radiation hydrodynamics (RHD) simulations by Hasegawa et al. have demonstrated that the collapse of low-mass (106-7 M⊙) gas clouds exposed to intense UV radiation can lead to the formation of compact star clusters like GCs if gas clouds contract with supersonic infall velocities. However, three-dimensional effects, such as the anisotropy of background radiation and the inhomogeneity in gas clouds, have not been studied so far. In this paper, we perform three-dimensional RHD simulations in a semicosmological context, and reconsider the formation of compact star clusters in strong UV radiation fields. As a result, we find that although anisotropic radiation fields bring an elongated shadow of neutral gas, almost spherical compact star clusters can be procreated from a `supersonic infall' cloud, since photodissociating radiation suppresses the formation of hydrogen molecules in the shadowed regions and the regions are compressed by UV heated ambient gas. The properties of resultant star clusters match those of GCs. On the other hand, in weak UV radiation fields, dark-matter-dominated star clusters with low stellar density form due to the self-shielding effect as well as the positive feedback by ionizing photons. Thus, we conclude that the `supersonic infall' under a strong UV background is a potential mechanism to form GCs.
Three-dimensional aerodynamic shape optimization using discrete sensitivity analysis
NASA Technical Reports Server (NTRS)
Burgreen, Gregory W.
1995-01-01
An aerodynamic shape optimization procedure based on discrete sensitivity analysis is extended to treat three-dimensional geometries. The function of sensitivity analysis is to directly couple computational fluid dynamics (CFD) with numerical optimization techniques, which facilitates the construction of efficient direct-design methods. The development of a practical three-dimensional design procedures entails many challenges, such as: (1) the demand for significant efficiency improvements over current design methods; (2) a general and flexible three-dimensional surface representation; and (3) the efficient solution of very large systems of linear algebraic equations. It is demonstrated that each of these challenges is overcome by: (1) employing fully implicit (Newton) methods for the CFD analyses; (2) adopting a Bezier-Bernstein polynomial parameterization of two- and three-dimensional surfaces; and (3) using preconditioned conjugate gradient-like linear system solvers. Whereas each of these extensions independently yields an improvement in computational efficiency, the combined effect of implementing all the extensions simultaneously results in a significant factor of 50 decrease in computational time and a factor of eight reduction in memory over the most efficient design strategies in current use. The new aerodynamic shape optimization procedure is demonstrated in the design of both two- and three-dimensional inviscid aerodynamic problems including a two-dimensional supersonic internal/external nozzle, two-dimensional transonic airfoils (resulting in supercritical shapes), three-dimensional transport wings, and three-dimensional supersonic delta wings. Each design application results in realistic and useful optimized shapes.
High Performance, Three-Dimensional Bilateral Filtering
Bethel, E. Wes
2008-06-05
Image smoothing is a fundamental operation in computer vision and image processing. This work has two main thrusts: (1) implementation of a bilateral filter suitable for use in smoothing, or denoising, 3D volumetric data; (2) implementation of the 3D bilateral filter in three different parallelization models, along with parallel performance studies on two modern HPC architectures. Our bilateral filter formulation is based upon the work of Tomasi [11], but extended to 3D for use on volumetric data. Our three parallel implementations use POSIX threads, the Message Passing Interface (MPI), and Unified Parallel C (UPC), a Partitioned Global Address Space (PGAS) language. Our parallel performance studies, which were conducted on a Cray XT4 supercomputer and aquad-socket, quad-core Opteron workstation, show our algorithm to have near-perfect scalability up to 120 processors. Parallel algorithms, such as the one we present here, will have an increasingly important role for use in production visual analysis systems as the underlying computational platforms transition from single- to multi-core architectures in the future.
Three-dimensional data assimilation for ionospheric reference scenarios
NASA Astrophysics Data System (ADS)
Gerzen, Tatjana; Wilken, Volker; Minkwitz, David; Hoque, Mainul M.; Schlüter, Stefan
2017-02-01
The reliable estimation of ionospheric refraction effects is an important topic in the GNSS (Global Navigation Satellite Systems) positioning and navigation domain, especially in safety-of-life applications. This paper describes a three-dimensional ionosphere reconstruction approach that combines three data sources with an ionospheric background model: space- and ground-based total electron content (TEC) measurements and ionosonde observations. First the background model is adjusted by F2 layer characteristics, obtained from space-based ionospheric radio occultation (IRO) profiles and ionosonde data, and secondly the final electron density distribution is estimated by an algebraic reconstruction technique.The method described is validated by TEC measurements of independent ground-based GNSS stations, space-based TEC from the Jason 1 and 2 satellites, and ionosonde observations. A significant improvement is achieved by the data assimilation, with a decrease in the residual errors by up to 98 % compared to the initial guess of the background. Furthermore, the results underpin the capability of space-based measurements to overcome data gaps in reconstruction areas where less GNSS ground-station infrastructure exists.
Three-dimensional warping registration of the pelvis and prostate
NASA Astrophysics Data System (ADS)
Fei, Baowei; Kemper, Corey; Wilson, David L.
2002-05-01
We are investigating interventional MRI guided radio- frequency (RF) thermal ablation for the minimally invasive treatment of prostate cancer. Among many potential applications of registration, we wish to compare registered MR images acquired before and immediately after RF ablation in order to determine whether a tumor is adequately treated. Warping registration is desired to correct for potential deformations of the pelvic region and movement of the prostate. We created a two-step, three-dimensional (3D) registration algorithm using mutual information and thin plate spline (TPS) warping for MR images. First, automatic rigid body registration was used to capture the global transformation. Second, local warping registration was applied. Interactively placed control points were automatically optimized by maximizing the mutual information of corresponding voxels in small volumes of interest and by using a 3D TPS to express the deformation throughout the image volume. Images were acquired from healthy volunteers in different conditions simulating potential applications. A variety of evaluation methods showed that warping consistently improved registration for volume pairs whenever patient position or condition was purposely changed between acquisitions. A TPS transformation based on 180 control points generated excellent warping throughout the pelvis following rigid body registration. The prostate centroid displacement for a typical volume pair was reduced from 3.4 mm to 0.6 mm when warping was added.
Three-dimensional parabolic equation modeling of mesoscale eddy deflection.
Heaney, Kevin D; Campbell, Richard L
2016-02-01
The impact of mesoscale oceanography, including ocean fronts and eddies, on global scale low-frequency acoustics is examined using a fully three-dimensional parabolic equation model. The narrowband acoustic signal, for frequencies from 2 to 16 Hz, is simulated from a seismic event on the Kerguellen Plateau in the South Indian Ocean to an array of receivers south of Ascension Island in the South Atlantic, a distance of 9100 km. The path was chosen for its relevance to seismic detections from the HA10 Ascension Island station of the International Monitoring System, for its lack of bathymetric interaction, and for the dynamic oceanography encountered as the sound passes the Cape of Good Hope. The acoustic field was propagated through two years (1992 and 1993) of the eddy-permitting ocean state estimation ECCO2 (Estimating the Circulation and Climate of the Ocean, Phase II) system. The range of deflection of the back-azimuth was 1.8° with a root-mean-square of 0.34°. The refraction due to mesoscale oceanography could therefore have significant impacts upon localization of distant low-frequency sources, such as seismic or nuclear test events.
Three-Dimensional Neurophenotyping of Adult Zebrafish Behavior
Cachat, Jonathan; Stewart, Adam; Utterback, Eli; Hart, Peter; Gaikwad, Siddharth; Wong, Keith; Kyzar, Evan; Wu, Nadine; Kalueff, Allan V.
2011-01-01
The use of adult zebrafish (Danio rerio) in neurobehavioral research is rapidly expanding. The present large-scale study applied the newest video-tracking and data-mining technologies to further examine zebrafish anxiety-like phenotypes. Here, we generated temporal and spatial three-dimensional (3D) reconstructions of zebrafish locomotion, globally assessed behavioral profiles evoked by several anxiogenic and anxiolytic manipulations, mapped individual endpoints to 3D reconstructions, and performed cluster analysis to reconfirm behavioral correlates of high- and low-anxiety states. The application of 3D swim path reconstructions consolidates behavioral data (while increasing data density) and provides a novel way to examine and represent zebrafish behavior. It also enables rapid optimization of video tracking settings to improve quantification of automated parameters, and suggests that spatiotemporal organization of zebrafish swimming activity can be affected by various experimental manipulations in a manner predicted by their anxiolytic or anxiogenic nature. Our approach markedly enhances the power of zebrafish behavioral analyses, providing innovative framework for high-throughput 3D phenotyping of adult zebrafish behavior. PMID:21408171
A Three-Dimensional Model of the Yeast Genome
Duan, Zhijun; Andronescu, Mirela; Schutz, Kevin; Mcllwain, Sean; Kim, Yoo Jung; Lee, Choli; Shendure, Jay; Fields, Stanley; Blau, C. Anthony; Noble, William S.
2010-01-01
Layered on top of information conveyed by DNA sequence and chromatin are higher order structures that encompass portions of chromosomes, entire chromosomes, and even whole genomes1-3. Interphase chromosomes are not positioned randomly within the nucleus but instead adopt preferred conformations4-7. Disparate DNA elements co-localize into functionally defined aggregates or “factories” for transcription8 and DNA replication9. In budding yeast, Drosophila and many other eukaryotes, chromosomes adopt a Rabl configuration, with arms extending from centromeres adjacent to the spindle pole body to telomeres that abut the nuclear envelope10-12. Nonetheless, the topologies and spatial relationships of chromosomes remain poorly understood. Here we developed a method to globally capture intra- and inter-chromosomal interactions, and applied it to generate a map at kilobase resolution of the haploid genome of Saccharomyces cerevisiae. The map recapitulates known features of genome organization, thereby validating the method, and identifies new features. Extensive regional and higher order folding of individual chromosomes is observed. Chromosome XII exhibits a striking conformation that implicates the nucleolus as a formidable barrier to interaction between DNA sequences at either end. Inter-chromosomal contacts are anchored by centromeres and include interactions among tRNA genes, among origins of early DNA replication and among sites where chromosomal breakpoints occur. Finally, we constructed a three-dimensional model of the yeast genome. Our findings provide a glimpse of the interface between the form and function of a eukaryotic genome. PMID:20436457
Three-dimensional ghost imaging lidar via sparsity constraint.
Gong, Wenlin; Zhao, Chengqiang; Yu, Hong; Chen, Mingliang; Xu, Wendong; Han, Shensheng
2016-05-17
Three-dimensional (3D) remote imaging attracts increasing attentions in capturing a target's characteristics. Although great progress for 3D remote imaging has been made with methods such as scanning imaging lidar and pulsed floodlight-illumination imaging lidar, either the detection range or application mode are limited by present methods. Ghost imaging via sparsity constraint (GISC), enables the reconstruction of a two-dimensional N-pixel image from much fewer than N measurements. By GISC technique and the depth information of targets captured with time-resolved measurements, we report a 3D GISC lidar system and experimentally show that a 3D scene at about 1.0 km range can be stably reconstructed with global measurements even below the Nyquist limit. Compared with existing 3D optical imaging methods, 3D GISC has the capability of both high efficiency in information extraction and high sensitivity in detection. This approach can be generalized in nonvisible wavebands and applied to other 3D imaging areas.
Three-dimensional ghost imaging lidar via sparsity constraint
Gong, Wenlin; Zhao, Chengqiang; Yu, Hong; Chen, Mingliang; Xu, Wendong; Han, Shensheng
2016-01-01
Three-dimensional (3D) remote imaging attracts increasing attentions in capturing a target’s characteristics. Although great progress for 3D remote imaging has been made with methods such as scanning imaging lidar and pulsed floodlight-illumination imaging lidar, either the detection range or application mode are limited by present methods. Ghost imaging via sparsity constraint (GISC), enables the reconstruction of a two-dimensional N-pixel image from much fewer than N measurements. By GISC technique and the depth information of targets captured with time-resolved measurements, we report a 3D GISC lidar system and experimentally show that a 3D scene at about 1.0 km range can be stably reconstructed with global measurements even below the Nyquist limit. Compared with existing 3D optical imaging methods, 3D GISC has the capability of both high efficiency in information extraction and high sensitivity in detection. This approach can be generalized in nonvisible wavebands and applied to other 3D imaging areas. PMID:27184530
Three-dimensional adaptive grid-embedding Euler technique
NASA Astrophysics Data System (ADS)
Davis, Roger L.; Dannenhoffer, John F., III
1994-06-01
A new three-dimensional adaptive-grid Euler procedure is presented that automatically detects high-gradient regions in the flow and locally subdivides the computational grid in these regions to provide a uniform, high level of accuracy over the entire domain. A tunable, semistructured data system is utilized that provides global topological unstructured-grid flexibility along with the efficiency of a local, structured-grid system. In addition, this structure data allows for the flow solution algorithm to be executed on a wide variety of parallel/vector computing platforms. An explicit, time-marching, control volume procedure is used to integrate the Euler equations to a steady state. In addition, a multiple-grid procedure is used throughout the embedded-grid regions as well as on subgrids coarser than the initial grid to accelerate convergence and properly propagate disturbance waves through refined-grid regions. Upon convergence, high flow gradient regions, where it is assumed that large truncation errors in the solution exist, are detected using a combination of directional refinement vectors that have large components in areas of these gradients. The local computational grid is directionally subdivided in these regions and the flow solution is reinitiated. Overall convergence occurs when a prespecified level of accuracy is reached. Solutions are presented that demonstrate the efficiency and accuracy of the present procedure.
Figure-ground organization based on three-dimensional symmetry
NASA Astrophysics Data System (ADS)
Michaux, Aaron; Jayadevan, Vijai; Delp, Edward; Pizlo, Zygmunt
2016-11-01
We present an approach to figure/ground organization using mirror symmetry as a general purpose and biologically motivated prior. Psychophysical evidence suggests that the human visual system makes use of symmetry in producing three-dimensional (3-D) percepts of objects. 3-D symmetry aids in scene organization because (i) almost all objects exhibit symmetry, and (ii) configurations of objects are not likely to be symmetric unless they share some additional relationship. No general purpose approach is known for solving 3-D symmetry correspondence in two-dimensional (2-D) camera images, because few invariants exist. Therefore, we present a general purpose method for finding 3-D symmetry correspondence by pairing the problem with the two-view geometry of the binocular correspondence problem. Mirror symmetry is a spatially global property that is not likely to be lost in the spatially local noise of binocular depth maps. We tested our approach on a corpus of 180 images collected indoors with a stereo camera system. K-means clustering was used as a baseline for comparison. The informative nature of the symmetry prior makes it possible to cluster data without a priori knowledge of which objects may appear in the scene, and without knowing how many objects there are in the scene.
Three-dimensional ghost imaging lidar via sparsity constraint
NASA Astrophysics Data System (ADS)
Gong, Wenlin; Zhao, Chengqiang; Yu, Hong; Chen, Mingliang; Xu, Wendong; Han, Shensheng
2016-05-01
Three-dimensional (3D) remote imaging attracts increasing attentions in capturing a target’s characteristics. Although great progress for 3D remote imaging has been made with methods such as scanning imaging lidar and pulsed floodlight-illumination imaging lidar, either the detection range or application mode are limited by present methods. Ghost imaging via sparsity constraint (GISC), enables the reconstruction of a two-dimensional N-pixel image from much fewer than N measurements. By GISC technique and the depth information of targets captured with time-resolved measurements, we report a 3D GISC lidar system and experimentally show that a 3D scene at about 1.0 km range can be stably reconstructed with global measurements even below the Nyquist limit. Compared with existing 3D optical imaging methods, 3D GISC has the capability of both high efficiency in information extraction and high sensitivity in detection. This approach can be generalized in nonvisible wavebands and applied to other 3D imaging areas.
Numerical Modeling of Three-Dimensional Confined Flows
NASA Technical Reports Server (NTRS)
Greywall, M. S.
1981-01-01
A three dimensional confined flow model is presented. The flow field is computed by calculating velocity and enthalpy along a set of streamlines. The finite difference equations are obtained by applying conservation principles to streamtubes constructed around the chosen streamlines. With appropriate substitutions for the body force terms, the approach computes three dimensional magnetohydrodynamic channel flows. A listing of a computer code, based on this approach is presented in FORTRAN IV language. The code computes three dimensional compressible viscous flow through a rectangular duct, with the duct cross section specified along the axis.
Three-dimensional particle imaging by wavefront sensing.
Towers, Catherine E; Towers, David P; Campbell, Heather I; Zhang, Sijiong; Greenaway, Alan H
2006-05-01
We present two methods for three-dimensional particle metrology from a single two-dimensional view. The techniques are based on wavefront sensing where the three-dimensional location of a particle is encoded into a single image plane. The first technique is based on multiplanar imaging, and the second produces three-dimensional location information via anamorphic distortion of the recorded images. Preliminary results show that an uncertainty of 8 microm in depth can be obtained for low-particle density over a thin plane, and an uncertainty of 30 microm for higher particle density over a 10 mm deep volume.
More About The Farley Three-Dimensional Braider
NASA Technical Reports Server (NTRS)
Farley, Gary L.
1993-01-01
Farley three-dimensional braider, undergoing development, is machine for automatic fabrication of three-dimensional braided structures. Incorporates yarns into structure at arbitrary braid angles to produce complicated shape. Braiding surface includes movable braiding segments containing pivot points, along which yarn carriers travel during braiding process. Yarn carrier travels along sequence of pivot points as braiding segments move. Combined motions position yarns for braiding onto preform. Intended for use in making fiber preforms for fiber/matrix composite parts, such as multiblade propellers. Machine also described in "Farley Three-Dimensional Braiding Machine" (LAR-13911).
Three-dimensional thinning by neural networks
NASA Astrophysics Data System (ADS)
Shen, Jun; Shen, Wei
1995-10-01
3D thinning is widely used in 3D object representation in computer vision and in trajectory planning in robotics to find the topological structure of the free space. In the present paper, we propose a 3D image thinning method by neural networks. Each voxel in the 3D image corresponds to a set of neurons, called 3D Thinron, in the network. Taking the 3D Thinron as the elementary unit, the global structure of the network is a 3D array in which each Thinron is connected with the 26 neighbors in the neighborhood 3 X 3 X 3. As to the Thinron itself, the set of neurons are organized in multiple layers. In the first layer, we have neurons for boundary analysis, connectivity analysis and connectivity verification, taking as input the voxels in the 3 X 3 X 3 neighborhood and the intermediate outputs of neighboring Thinrons. In the second layer, we have the neurons for synthetical analysis to give the intermediate output of Thinron. In the third layer, we have the decision neurons whose state determines the final output. All neurons in the Thinron are the adaline neurons of Widrow, except the connectivity analysis and verification neurons which are nonlinear neurons. With the 3D Thinron neural network, the state transition of the network will take place automatically, and the network converges to the final steady state, which gives the result medial surface of 3D objects, preserving the connectivity in the initial image. The method presented is simulated and tested for 3D images, experimental results are reported.
Oscillatory cellular patterns in three-dimensional directional solidification
NASA Astrophysics Data System (ADS)
Tourret, D.; Debierre, J.-M.; Song, Y.; Mota, F. L.; Bergeon, N.; Guérin, R.; Trivedi, R.; Billia, B.; Karma, A.
2015-10-01
We present a phase-field study of oscillatory breathing modes observed during the solidification of three-dimensional cellular arrays in microgravity. Directional solidification experiments conducted onboard the International Space Station have allowed us to observe spatially extended homogeneous arrays of cells and dendrites while minimizing the amount of gravity-induced convection in the liquid. In situ observations of transparent alloys have revealed the existence, over a narrow range of control parameters, of oscillations in cellular arrays with a period ranging from about 25 to 125 min. Cellular patterns are spatially disordered, and the oscillations of individual cells are spatiotemporally uncorrelated at long distance. However, in regions displaying short-range spatial ordering, groups of cells can synchronize into oscillatory breathing modes. Quantitative phase-field simulations show that the oscillatory behavior of cells in this regime is linked to a stability limit of the spacing in hexagonal cellular array structures. For relatively high cellular front undercooling (i.e., low growth velocity or high thermal gradient), a gap appears in the otherwise continuous range of stable array spacings. Close to this gap, a sustained oscillatory regime appears with a period that compares quantitatively well with experiment. For control parameters where this gap exists, oscillations typically occur for spacings at the edge of the gap. However, after a change of growth conditions, oscillations can also occur for nearby values of control parameters where this gap just closes and a continuous range of spacings exists. In addition, sustained oscillations at to the opening of this stable gap exhibit a slow periodic modulation of the phase-shift among cells with a slower period of several hours. While long-range coherence of breathing modes can be achieved in simulations for a perfect spatial arrangement of cells as initial condition, global disorder is observed in both
Oscillatory cellular patterns in three-dimensional directional solidification
Tourret, D.; Debierre, J. -M.; Song, Y.; ...
2015-09-11
We present a phase-field study of oscillatory breathing modes observed during the solidification of three-dimensional cellular arrays in micro-gravity. Directional solidification experiments conducted onboard the International Space Station have allowed for the first time to observe spatially extended homogeneous arrays of cells and dendrites while minimizing the amount of gravity-induced convection in the liquid. In situ observations of transparent alloys have revealed the existence, over a narrow range of control parameters, of oscillations in cellular arrays with a period ranging from about 25 to 125 minutes. Cellular patterns are spatially disordered, and the oscillations of individual cells are spatiotemporally uncorrelatedmore » at long distance. However, in regions displaying short-range spatial ordering, groups of cells can synchronize into oscillatory breathing modes. Quantitative phase-field simulations show that the oscillatory behavior of cells in this regime is linked to a stability limit of the spacing in hexagonal cellular array structures. For relatively high cellular front undercooling (\\ie low growth velocity or high thermal gradient), a gap appears in the otherwise continuous range of stable array spacings. Close to this gap, a sustained oscillatory regime appears with a period that compares quantitatively well with experiment. For control parameters where this gap exist, oscillations typically occur for spacings at the edge of the gap. However, after a change of growth conditions, oscillations can also occur for nearby values of control parameters where this gap just closes and a continuous range of spacings exists. In addition, sustained oscillations at to the opening of this stable gap exhibit a slow periodic modulation of the phase-shift among cells with a slower period of several hours. While long-range coherence of breathing modes can be achieved in simulations for a perfect spatial arrangement of cells as initial condition, global
Oscillatory cellular patterns in three-dimensional directional solidification
Tourret, D.; Debierre, J. -M.; Song, Y.; Mota, F. L.; Bergeon, N.; Guerin, R.; Trivedi, R.; Billia, B.; Karma, A.
2015-09-11
We present a phase-field study of oscillatory breathing modes observed during the solidification of three-dimensional cellular arrays in micro-gravity. Directional solidification experiments conducted onboard the International Space Station have allowed for the first time to observe spatially extended homogeneous arrays of cells and dendrites while minimizing the amount of gravity-induced convection in the liquid. In situ observations of transparent alloys have revealed the existence, over a narrow range of control parameters, of oscillations in cellular arrays with a period ranging from about 25 to 125 minutes. Cellular patterns are spatially disordered, and the oscillations of individual cells are spatiotemporally uncorrelated at long distance. However, in regions displaying short-range spatial ordering, groups of cells can synchronize into oscillatory breathing modes. Quantitative phase-field simulations show that the oscillatory behavior of cells in this regime is linked to a stability limit of the spacing in hexagonal cellular array structures. For relatively high cellular front undercooling (\\ie low growth velocity or high thermal gradient), a gap appears in the otherwise continuous range of stable array spacings. Close to this gap, a sustained oscillatory regime appears with a period that compares quantitatively well with experiment. For control parameters where this gap exist, oscillations typically occur for spacings at the edge of the gap. However, after a change of growth conditions, oscillations can also occur for nearby values of control parameters where this gap just closes and a continuous range of spacings exists. In addition, sustained oscillations at to the opening of this stable gap exhibit a slow periodic modulation of the phase-shift among cells with a slower period of several hours. While long-range coherence of breathing modes can be achieved in simulations for a perfect spatial arrangement of cells as initial condition, global disorder is
Global star formation in the L1630 molecular cloud
NASA Technical Reports Server (NTRS)
Lada, Elizabeth A.
1992-01-01
The first systematic and coordinated surveys for both dense gas and young stellar objects within a single molecular cloud, the L1630 molecular cloud are compared. It is found that (1) star formation in the L1630 molecular cloud occurs almost exclusively within the dense gas; (2) star formation does not occur uniformly throughout the dense gas and is strongly favored in a few very massive dense cores, where efficient conversion of molecular gas into stars has resulted in the production of rich stellar clusters; and (3) high gas densities and high gas mass may be necessary but not sufficient conditions for the formation of star clusters since two of the five most massive dense cores in the cloud have very low levels of star formation activity.
Interactive dynamic three-dimensional scene for the ground-based three-dimensional display
NASA Astrophysics Data System (ADS)
Hou, Peining; Sang, Xinzhu; Guo, Nan; Chen, Duo; Yan, Binbin; Wang, Kuiru; Dou, Wenhua; Xiao, Liquan
2016-10-01
Three-dimensional (3D) displays provides valuable tools for many fields, such as scientific experiment, education, information transmission, medical imaging and physical simulation. Ground based 360° 3D display with dynamic and controllable scene can find some special applications, such as design and construction of buildings, aeronautics, military sand table and so on. It can be utilized to evaluate and visualize the dynamic scene of the battlefield, surgical operation and the 3D canvas of art. In order to achieve the ground based 3D display, the public focus plane should be parallel to the camera's imaging planes, and optical axes should be offset to the center of public focus plane in both vertical and horizontal directions. Virtual cameras are used to display 3D dynamic scene with Unity 3D engine. Parameters of virtual cameras for capturing scene are designed and analyzed, and locations of virtual cameras are determined by the observer's eye positions in the observing space world. An interactive dynamic 3D scene for ground based 360° 3D display is demonstrated, which provides high-immersion 3D visualization.
Three-dimensional reconstructions of solid surfaces using conventional microscopes.
Ficker, Tomáš; Martišek, Dalibor
2016-01-01
The three-dimensional digital replicas of solid surfaces are subject of interest of different branches of science and technology. The present paper in its introductory parts brings an overview of the various microscopic reconstructive techniques based on optical sectioning. The main attention is devoted to conventional reconstruction methods and especially to that one employing the Fourier transform. The three-dimensional replicas of this special reconstructive frequency method are compared graphically and numerically with the three-dimensional replicas of the confocal method. Based on the comparative study it has been concluded that the quality of the conventional replicas of surfaces possessing textures of intermediate height irregularities is acceptable and almost comparable with the quality of confocal replicas. This study is relevant both for identifying a convenient technique that provides good qualities of three-dimensional replicas and for selecting the hardware whose price is affordable even for small research groups studying rougher surface textures.
Direct Linear Transformation Method for Three-Dimensional Cinematography
ERIC Educational Resources Information Center
Shapiro, Robert
1978-01-01
The ability of Direct Linear Transformation Method for three-dimensional cinematography to locate points in space was shown to meet the accuracy requirements associated with research on human movement. (JD)
Three-dimensional Simulation of Backward Raman Amplification
A.A. Balakin; G.M. Fraiman; N.J. Fisch
2005-11-12
Three-dimensional (3-D) simulations for the Backward Raman Amplification (BRA) are presented. The images illustrate the effects of pump depletion, pulse diffraction, non-homogeneous plasma density, and plasma ionization.
Improving Students' Sense of Three-Dimensional Shapes.
ERIC Educational Resources Information Center
Leeson, Neville J.
1994-01-01
Describes activities to be used with fifth and sixth graders to improve students' spatial sense with respect to three-dimensional shapes. Includes the use of cubes, triangular prisms, tetrahedrons, and square pyramids. (MKR)
Analysis and validation of carbohydrate three-dimensional structures
Lütteke, Thomas
2009-02-01
The article summarizes the information that is gained from and the errors that are found in carbohydrate structures in the Protein Data Bank. Validation tools that can locate these errors are described. Knowledge of the three-dimensional structures of the carbohydrate molecules is indispensable for a full understanding of the molecular processes in which carbohydrates are involved, such as protein glycosylation or protein–carbohydrate interactions. The Protein Data Bank (PDB) is a valuable resource for three-dimensional structural information on glycoproteins and protein–carbohydrate complexes. Unfortunately, many carbohydrate moieties in the PDB contain inconsistencies or errors. This article gives an overview of the information that can be obtained from individual PDB entries and from statistical analyses of sets of three-dimensional structures, of typical problems that arise during the analysis of carbohydrate three-dimensional structures and of the validation tools that are currently available to scientists to evaluate the quality of these structures.
Construction of Three Dimensional Solutions for the Maxwell Equations
NASA Technical Reports Server (NTRS)
Yefet, A.; Turkel, E.
1998-01-01
We consider numerical solutions for the three dimensional time dependent Maxwell equations. We construct a fourth order accurate compact implicit scheme and compare it to the Yee scheme for free space in a box.
Three-dimensional pattern transfer and nanolithography: modified soft molding
NASA Astrophysics Data System (ADS)
Kim, Y. S.; Park, Joonhyung; Lee, Hong H.
2002-08-01
One-step transfer of molded three-dimensional polymer structures into underlying substrate is reported. The one-step transfer is made possible by a molding technique presented here in the form of modified soft molding. Formation of a desired three-dimensional structure in a polymer film by this method, followed by one-step reactive ion etching, is utilized for the transfer. The technique is also shown to be effective in transferring sub-100-nm features.
Uniform Deterministic Discrete Method for three dimensional systems
NASA Astrophysics Data System (ADS)
Li, Ben-Wen; Tao, Wen-Quan; Nie, Yu-Hong
1997-06-01
For radiative direct exchange areas in three dimensional system, the Uniform Deterministic Discrete Method (UDDM) was adopted. The spherical surface dividing method for sending area element and the regular icosahedron for sending volume element can meet with the direct exchange area computation of any kind of zone pairs. The numerical examples of direct exchange area in three dimensional system with nonhomogeneous attenuation coefficients indicated that the UDDM can give very high numerical accuracy.
Three-dimensional study of the multi-cavity FEL
Krishnagopal, S.; Kumar, V.
1995-12-31
The Multi-Cavity Free-Electron Laser has been proposed earlier, as a new configuration to obtain short, intense pulses of radiation, the key idea being to pre-bunch the electron beam in a number of very short cavities. Those studies were one-dimensional. Here we use three-dimensional simulations to study the viability of this concept when three-dimensional effects are included, particularly with regard to the transverse modes of the optical beam.
Nonlinear wave interaction problems in the three-dimensional case
NASA Astrophysics Data System (ADS)
Curró, C.; Manganaro, N.; Pavlov, M. V.
2017-01-01
Three-dimensional nonlinear wave interactions have been analytically described. The procedure under interest can be applied to three-dimensional quasilinear systems of first order, whose hydrodynamic reductions are homogeneous semi-Hamiltonian hydrodynamic type systems (i.e. possess diagonal form and infinitely many conservation laws). The interaction of N waves was studied. In particular we prove that they behave like simple waves and they distort after the collision region. The amount of the distortion can be analytically computed.
Effect of three-dimensionality on compressible mixing
Papamoschou, D. )
1992-02-01
Existing experimental data and hypotheses on the growth rates of compressible and incompressible turbulent shear layers are used to estimate the effect of three-dimensionality in the turbulent mixing enhancement in compressible shear flows that is critically important to the efficiency of scramjet powerplants. The general trend is found to be a decrease in growth rate with increasing three-dimensionality, excepting only the restricted regime, where the growth-rate increase is modest. 9 refs.
Initialization and Simulation of Three-Dimensional Aircraft Wake Vortices
NASA Technical Reports Server (NTRS)
Ash, Robert L.; Zheng, Z. C.
1997-01-01
This paper studies the effects of axial velocity profiles on vortex decay, in order to properly initialize and simulate three-dimensional wake vortex flow. Analytical relationships are obtained based on a single vortex model and computational simulations are performed for a rather practical vortex wake, which show that the single vortex analytical relations can still be applicable at certain streamwise sections of three-dimensional wake vortices.
Boundedness in a three-dimensional chemotaxis-haptotaxis model
NASA Astrophysics Data System (ADS)
Cao, Xinru
2016-03-01
This paper studies the chemotaxis-haptotaxis system left\\{begin{array}{lll} u_t = Δ u - χnabla \\cdot (unabla v) - ξnabla \\cdot (unabla w) + μ u(1 - u - w), &quad(x, t)in Ω × (0, T),\\ v_t = Δ v - v + u, &quad(x, t) in Ω × (0, T),\\ w_t= - vw, &quad(x, t)in Ω × (0,T) right.quadquad(star) under Neumann boundary conditions. Here, {Ω subset {{R}}^3} is a bounded domain with smooth boundary and the parameters {ξ,χ,μ > 0}. We prove that for nonnegative and suitably smooth initial data {(u_0, v_0, w_0)}, if {χ/μ} is sufficiently small, ({star}) possesses a global classical solution, which is bounded in {Ω × (0, infty)}. We underline that the result fully parallels the corresponding parabolic-elliptic-ODE system.
Ordered three-dimensional interconnected nanoarchitectures in anodic porous alumina
Martín, Jaime; Martín-González, Marisol; Fernández, Jose Francisco; Caballero-Calero, Olga
2014-01-01
Three-dimensional nanostructures combine properties of nanoscale materials with the advantages of being macro-sized pieces when the time comes to manipulate, measure their properties, or make a device. However, the amount of compounds with the ability to self-organize in ordered three-dimensional nanostructures is limited. Therefore, template-based fabrication strategies become the key approach towards three-dimensional nanostructures. Here we report the simple fabrication of a template based on anodic aluminum oxide, having a well-defined, ordered, tunable, homogeneous 3D nanotubular network in the sub 100 nm range. The three-dimensional templates are then employed to achieve three-dimensional, ordered nanowire-networks in Bi2Te3 and polystyrene. Lastly, we demonstrate the photonic crystal behavior of both the template and the polystyrene three-dimensional nanostructure. Our approach may establish the foundations for future high-throughput, cheap, photonic materials and devices made of simple commodity plastics, metals, and semiconductors. PMID:25342247
Integrated Aeromechanics with Three-Dimensional Solid-Multibody Structures
NASA Technical Reports Server (NTRS)
Datta, Anubhav; Johnson, Wayne
2014-01-01
A full three-dimensional finite element-multibody structural dynamic solver is coupled to a three-dimensional Reynolds-averaged Navier-Stokes solver for the prediction of integrated aeromechanical stresses and strains on a rotor blade in forward flight. The objective is to lay the foundations of all major pieces of an integrated three-dimensional rotor dynamic analysis - from model construction to aeromechanical solution to stress/strain calculation. The primary focus is on the aeromechanical solution. Two types of three-dimensional CFD/CSD interfaces are constructed for this purpose with an emphasis on resolving errors from geometry mis-match so that initial-stage approximate structural geometries can also be effectively analyzed. A three-dimensional structural model is constructed as an approximation to a UH-60A-like fully articulated rotor. The aerodynamic model is identical to the UH-60A rotor. For preliminary validation measurements from a UH-60A high speed flight is used where CFD coupling is essential to capture the advancing side tip transonic effects. The key conclusion is that an integrated aeromechanical analysis is indeed possible with three-dimensional structural dynamics but requires a careful description of its geometry and discretization of its parts.
Impacts of rotation on three-dimensional hydrodynamics of core-collapse supernovae
Nakamura, Ko; Kuroda, Takami; Kotake, Kei; Takiwaki, Tomoya
2014-09-20
We perform a series of simplified numerical experiments to explore how rotation impacts the three-dimensional (3D) hydrodynamics of core-collapse supernovae. For our systematic study, we employ a light-bulb scheme to trigger explosions and a three-flavor neutrino leakage scheme to treat deleptonization effects and neutrino losses from the proto-neutron-star interior. Using a 15 M {sub ☉} progenitor, we compute 30 models in 3D with a wide variety of initial angular momentum and light-bulb neutrino luminosity. We find that the rotation can help the onset of neutrino-driven explosions for the models in which the initial angular momentum is matched to that obtained in recent stellar evolutionary calculations (∼0.3-3 rad s{sup –1} at the center). For the models with larger initial angular momentum, the shock surface deforms to be more oblate due to larger centrifugal force. This not only makes the gain region more concentrated around the equatorial plane, but also makes the mass larger in the gain region. As a result, buoyant bubbles tend to be coherently formed and rise in the equatorial region, which pushes the revived shock toward ever larger radii until a global explosion is triggered. We find that these are the main reasons that the preferred direction of the explosion in 3D rotating models is often perpendicular to the spin axis, which is in sharp contrast to the polar explosions around the axis that were obtained in previous two-dimensional simulations.
Shawkey, Matthew D.; Saranathan, Vinodkumar; Pálsdóttir, Hildur; Crum, John; Ellisman, Mark H.; Auer, Manfred; Prum, Richard O.
2009-01-01
Organismal colour can be created by selective absorption of light by pigments or light scattering by photonic nanostructures. Photonic nanostructures may vary in refractive index over one, two or three dimensions and may be periodic over large spatial scales or amorphous with short-range order. Theoretical optical analysis of three-dimensional amorphous nanostructures has been challenging because these structures are difficult to describe accurately from conventional two-dimensional electron microscopy alone. Intermediate voltage electron microscopy (IVEM) with tomographic reconstruction adds three-dimensional data by using a high-power electron beam to penetrate and image sections of material sufficiently thick to contain a significant portion of the structure. Here, we use IVEM tomography to characterize a non-iridescent, three-dimensional biophotonic nanostructure: the spongy medullary layer from eastern bluebird Sialia sialis feather barbs. Tomography and three-dimensional Fourier analysis reveal that it is an amorphous, interconnected bicontinuous matrix that is appropriately ordered at local spatial scales in all three dimensions to coherently scatter light. The predicted reflectance spectra from the three-dimensional Fourier analysis are more precise than those predicted by previous two-dimensional Fourier analysis of transmission electron microscopy sections. These results highlight the usefulness, and obstacles, of tomography in the description and analysis of three-dimensional photonic structures. PMID:19158016
Equilibrium Initialization and Stability of Three-Dimensional Gas Disks
Wang, Hsiang-Hsu; Klessen, Ralf S.; Dullemond, Cornelis P.; Bosch, Frank C.van den; Fuchs, Burkhard; /KIPAC, Menlo Park
2010-08-25
We present a new systematic way of setting up galactic gas disks based on the assumption of detailed hydrodynamic equilibrium. To do this, we need to specify the density distribution and the velocity field which supports the disk. We first show that the required circular velocity has no dependence on the height above or below the midplane so long as the gas pressure is a function of density only. The assumption of disks being very thin enables us to decouple the vertical structure from the radial direction. Based on that, the equation of hydrostatic equilibrium together with the reduced Poisson equation leads to two sets of second-order non-linear differential equation, which are easily integrated to set-up a stable disk. We call one approach 'density method' and the other one 'potential method'. Gas disks in detailed balance are especially suitable for investigating the onset of the gravitational instability. We revisit the question of global, axisymmetric instability using fully three-dimensional disk simulations. The impact of disk thickness on the disk instability and the formation of spontaneously induced spirals is studied systematically with or without the presence of the stellar potential. In our models, the numerical results show that the threshold value for disk instability is shifted from unity to 0.69 for self-gravitating thick disks and to 0.75 for combined stellar and gas thick disks. The simulations also show that self-induced spirals occur in the correct regions and with the right numbers as predicted by the analytic theory.
Three-dimensional cellular deformation analysis with a two-photon magnetic manipulator workstation.
Huang, Hayden; Dong, Chen Y; Kwon, Hyuk-Sang; Sutin, Jason D; Kamm, Roger D; So, Peter T C
2002-01-01
The ability to apply quantifiable mechanical stresses at the microscopic scale is critical for studying cellular responses to mechanical forces. This necessitates the use of force transducers that can apply precisely controlled forces to cells while monitoring the responses noninvasively. This paper describes the development of a micromanipulation workstation integrating two-photon, three-dimensional imaging with a high-force, uniform-gradient magnetic manipulator. The uniform-gradient magnetic field applies nearly uniform forces to a large cell population, permitting statistical quantification of select molecular responses to mechanical stresses. The magnetic transducer design is capable of exerting over 200 pN of force on 4.5-microm-diameter paramagnetic particles and over 800 pN on 5.0-microm ferromagnetic particles. These forces vary within +/-10% over an area 500 x 500 microm2. The compatibility with the use of high numerical aperture (approximately 1.0) objectives is an integral part of the workstation design allowing submicron-resolution, three-dimensional, two-photon imaging. Three-dimensional analyses of cellular deformation under localized mechanical strain are reported. These measurements indicate that the response of cells to large focal stresses may contain three-dimensional global deformations and show the suitability of this workstation to further studying cellular response to mechanical stresses. PMID:11916876
Analyses of three-dimensional flow calculations in a driven cavity
NASA Astrophysics Data System (ADS)
Reima Iwatsu; Jae Min Hyun; Kunio Kuwahara
1990-07-01
Comprehensive numerical solutions of three-dimensional flows of an incompressible viscous fluid confined in a square cubic cavity are presented. The flow is maintained by the upper surface of the cavity, which slides in its own plane at a constant speed. Extensive numerical solutions to the governing Navier-Stokes equations were acquired over a wide range of the Reynolds numbers.Re ⩽ 2000. The previous report depicted the global structures of these complex three-dimensional flows at varying Re. The preceding account demonstrated broad agreement between the numerical results and the available experimental observations in gross flow characteristics. The present paper continues to give expanded description of the flows, in particular, the detailed velocity profiles along the vertical and horizontal symmetry lines. The changes in the main character of flow with increasing Re are elaborated. The conspicuous three-dimensionalities, at high Re exemplified by substantial transverse gradients of the velocities, as a result of the Taylor-Görtler-like vortices and the comer vortices, are delineated. Taking advantage of the wealth of the numerical results, diagnostic studies of the major terms in the momentum equations are conducted. These studies reveal the dominant dynamic balances in various parts of the flow field. The characterizations of the three-dimensional nature of the flow, based on the present numerical results, are in accord with the prior experimental visualizations.
SAGITTARIUS STREAM THREE-DIMENSIONAL KINEMATICS FROM SLOAN DIGITAL SKY SURVEY STRIPE 82
Koposov, Sergey E.; Belokurov, Vasily; Evans, N. Wyn
2013-04-01
Using multi-epoch observations of the Stripe 82 region from the Sloan Digital Sky Survey (SDSS), we measure precise statistical proper motions of the stars in the Sagittarius (Sgr) stellar stream. The multi-band photometry and SDSS radial velocities allow us to efficiently select Sgr members and thus enhance the proper-motion precision to {approx}0.1 mas yr{sup -1}. We measure separately the proper motion of a photometrically selected sample of the main-sequence turn-off stars, as well as spectroscopically selected Sgr giants. The data allow us to determine the proper motion separately for the two Sgr streams in the south found in Koposov et al. Together with the precise velocities from SDSS, our proper motions provide exquisite constraints of the three-dimensional motions of the stars in the Sgr streams.
NASA Astrophysics Data System (ADS)
Endeve, Eirik; Cardall, C.; Budiardja, R.; Beck, S.; Bejnood, A.; Mezzacappa, A.
2011-01-01
The stationary accretion shock instability (SASI) plays an important role in modern simulations of core-collapse supernovae. With the intent to study magnetic field generation and the possible impact of magnetic fields during the crucial nonlinear phase leading to the explosion of massive stars, we have carried out high-resolution, three-dimensional magnetohydrodynamic simulations of the SASI. Turbulent flows emerging from the operation of the spiral SASI mode result in exponential growth of the magnetic energy. From initial conditions in the range expected for slowly rotating progenitor stars, we find that saturation of the magnetic energy can occur within a typical explosion time scale. Implications for neutrino-powered supernovae and neutron star magnetization are considered.
A moving observer in a three-dimensional world
2016-01-01
For many tasks such as retrieving a previously viewed object, an observer must form a representation of the world at one location and use it at another. A world-based three-dimensional reconstruction of the scene built up from visual information would fulfil this requirement, something computer vision now achieves with great speed and accuracy. However, I argue that it is neither easy nor necessary for the brain to do this. I discuss biologically plausible alternatives, including the possibility of avoiding three-dimensional coordinate frames such as ego-centric and world-based representations. For example, the distance, slant and local shape of surfaces dictate the propensity of visual features to move in the image with respect to one another as the observer's perspective changes (through movement or binocular viewing). Such propensities can be stored without the need for three-dimensional reference frames. The problem of representing a stable scene in the face of continual head and eye movements is an appropriate starting place for understanding the goal of three-dimensional vision, more so, I argue, than the case of a static binocular observer. This article is part of the themed issue ‘Vision in our three-dimensional world’. PMID:27269608
Biodynamic profiling of three-dimensional tissue growth techniques
NASA Astrophysics Data System (ADS)
Sun, Hao; Merrill, Dan; Turek, John; Nolte, David
2016-03-01
Three-dimensional tissue culture presents a more biologically relevant environment in which to perform drug development than conventional two-dimensional cell culture. However, obtaining high-content information from inside three dimensional tissue has presented an obstacle to rapid adoption of 3D tissue culture for pharmaceutical applications. Biodynamic imaging is a high-content three-dimensional optical imaging technology based on low-coherence interferometry and digital holography that uses intracellular dynamics as high-content image contrast. In this paper, we use biodynamic imaging to compare pharmaceutical responses to Taxol of three-dimensional multicellular spheroids grown by three different growth techniques: rotating bioreactor, hanging-drop and plate-grown spheroids. The three growth techniques have systematic variations among tissue cohesiveness and intracellular activity and consequently display different pharmacodynamics under identical drug dose conditions. The in vitro tissue cultures are also compared to ex vivo living biopsies. These results demonstrate that three-dimensional tissue cultures are not equivalent, and that drug-response studies must take into account the growth method.
Visualization techniques for improved orientation in three-dimensional echocardiography
NASA Astrophysics Data System (ADS)
Wolf, Ivo; de Simone, Raffaele; Hastenteufel, Mark; Mottl-Link, Sibylle; Meinzer, Hans-Peter
2002-05-01
Repair of a defect heart valve is of great advantage for the patient in comparison to replacement with a prosthesis. The applicability and the success of heart valve repair can be improved by an exact diagnosis of the valve's pathological modification. The best way for imaging heart valve insufficiencies is echocardiography, since it is fast, relatively cheap, can be used intraoperatively and provides information about morphology as well as blood flow. Three-dimensional echocardiography has been proven to be superior to conventional echocardiographic techniques. Although the overall structures are much better displayed by three-dimensional visualization methods, it is sometimes difficult to comprehend the orientation of the scene, since anatomical landmarks like the aortic outflow tract may be hidden by other structures. Also, such anatomical landmarks often are only partly contained in the acquired data set so that they are clearly visible in a few slices only, making them difficult to find in a three-dimensional visualization. The knowledge of the absolute orientation is of essential value for the surgeon to mentally transfer the preoperatively acquired data to the intraoperative situs. Therefore, it is desirable to have additional hints for orientation in the three-dimensional scene. We present methods that enable better and easier orientation and therefore improve the usability of three-dimensional echocardiography.
Radiation hardness of three-dimensional polycrystalline diamond detectors
Lagomarsino, Stefano Sciortino, Silvio; Bellini, Marco; Corsi, Chiara; Cindro, Vladimir; Kanxheri, Keida; Servoli, Leonello; Morozzi, Arianna; Passeri, Daniele; Schmidt, Christian J.
2015-05-11
The three-dimensional concept in particle detection is based on the fabrication of columnar electrodes perpendicular to the surface of a solid state radiation sensor. It permits to improve the radiation resistance characteristics of a material by lowering the necessary bias voltage and shortening the charge carrier path inside the material. If applied to a long-recognized exceptionally radiation-hard material like diamond, this concept promises to pave the way to the realization of detectors of unprecedented performances. We fabricated conventional and three-dimensional polycrystalline diamond detectors, and tested them before and after neutron damage up to 1.2 ×10{sup 16 }cm{sup −2}, 1 MeV-equivalent neutron fluence. We found that the signal collected by the three-dimensional detectors is up to three times higher than that of the conventional planar ones, at the highest neutron damage ever experimented.
Ray tracing a three dimensional scene using a grid
Wald, Ingo; Ize, Santiago; Parker, Steven G; Knoll, Aaron
2013-02-26
Ray tracing a three-dimensional scene using a grid. One example embodiment is a method for ray tracing a three-dimensional scene using a grid. In this example method, the three-dimensional scene is made up of objects that are spatially partitioned into a plurality of cells that make up the grid. The method includes a first act of computing a bounding frustum of a packet of rays, and a second act of traversing the grid slice by slice along a major traversal axis. Each slice traversal includes a first act of determining one or more cells in the slice that are overlapped by the frustum and a second act of testing the rays in the packet for intersection with any objects at least partially bounded by the one or more cells overlapped by the frustum.
Shape memory polymers: three-dimensional isotropic modeling
NASA Astrophysics Data System (ADS)
Balogun, Olaniyi; Mo, Changki
2014-04-01
This paper presents a comprehensive three-dimensional isotropic numerical simulation for a thermo-mechanical constitutive model of shape memory polymers (SMPs). In order to predict the thermo-mechanical behavior of SMPs, a one-dimensional rheological thermo-mechanical constitutive model is adopted, translated into a three-dimensional form and a time discrete form of the three-dimensional model is then presented. Numerical simulation of this model was developed using the UMAT subroutine capabilities of the finite element software ABAQUS. Evolution of the analysis was conducted by making use of the backward difference scheme, which was applied to all quantities within the model, including the material properties. A comparison of the numerical simulation results was carried out with the available experimental data. Numerical simulation results clearly exhibit the thermo-mechanical properties of the material which include shape fixity, shape recovery, and recovery stress. Finally, a prediction for the transverse and shear directions of the material is presented.
Three-dimensional diamagnetic particle deflection in ferrofluid microchannel flows.
Liang, Litao; Zhu, Junjie; Xuan, Xiangchun
2011-09-01
Magnetic field-induced particle manipulation is a promising technique for biomicrofluidics applications. It is simple, cheap, and also free of fluid heating issues that accompany other common electric, acoustic, and optical methods. This work presents a fundamental study of diamagnetic particle motion in ferrofluid flows through a rectangular microchannel with a nearby permanent magnet. Due to their negligible magnetization relative to the ferrofluid, diamagnetic particles experience negative magnetophoresis and are repelled away from the magnet. The result is a three-dimensionally focused particle stream flowing near the bottom outer corner of the microchannel that is the farthest to the center of the magnet and hence has the smallest magnetic field. The effects of the particle's relative position to the magnet, particle size, ferrofluid flow rate, and concentration on this three-dimensional diamagnetic particle deflection are systematically studied. The obtained experimental results agree quantitatively with the predictions of a three-dimensional analytical model.
Antimicrobial-finished textile three-dimensional structures.
Heide, M; Möhring, U; Hänsel, R; Stoll, M; Wollina, U; Heinig, B
2006-01-01
This paper describes the possibilities of antimicrobial finishing of three-dimensional spacer fabrics and its applications, and gives information about the different effects. A research project of the Textilforschungsinstitut Thüringen-Vogtland Greiz is presented in which medical shoe insoles, based on specially manufactured three-dimensional spacer fabrics, made of permanently effective antimicrobial yarns were used for interesting and functional textile products. Furthermore, work of the research institute Forschungsinstitut für Leder und Kunststoffbahnen Freiberg is presented which describes the silver-coating process and application of textile materials using antimicrobial substances. The chemical and mechanical stability is investigated, and proof of the effectiveness is supplied. The results show that in the three-dimensional spacer fabrics both - antimicrobial yarn materials and thin silver films with antimicrobial substances - can achieve an antimicrobial effect, even in low quantities.
Time of Closest Approach in Three-Dimensional Airspace
NASA Technical Reports Server (NTRS)
Munoz, Cesar A.; Narkawicz, Anthony J.
2010-01-01
In air traffic management, the aircraft separation requirement is defined by a minimum horizontal distance and a minimum vertical distance that the aircraft have to maintain. Since this requirement defines a cylinder around each aircraft rather than a sphere, the three-dimensional Euclidean distance does not provide an appropriate basis for the definition of time of closest approach. For instance, conflicting aircraft are not necessarily in loss of separation at the time of closest three-dimensional Euclidean distance. This paper proposes a definition of time of closest approach that characterizes conflicts in a three-dimensional airspace. The proposed time is defined as the time that minimizes a distance metric called cylindrical norm. An algorithm that computes the time of closest approach between two aircraft is provided and the formal verification of its main properties is reported.
Coupled particle dispersion by three-dimensional vortex structures
Troutt, T.R.; Chung, J.N.; Crowe, C.T.
1996-12-31
The primary objective of this research program is to obtain understanding concerning the role of three-dimensional vortex structures in the dispersion of particles and droplets in free shear flows. This research program builds on previous studies which focused on the nature of particle dispersion in large scale quasi two-dimensional vortex structures. This investigation employs time dependent experimental and numerical techniques to provide information concerning the particulate dispersion produced by three dimensional vortex structures in free shear layers. The free shear flows investigated include modified plane mixing layers, and modified plane wakes. The modifications to these flows involve slight perturbations to the initiation boundary conditions such that three-dimensional vortex structures are rapidly generated by the experimental and numerical flow fields. Recent results support the importance of these vortex structures in the particle dispersion process.
Three-dimensional numerical simulations of falling liquid films
NASA Astrophysics Data System (ADS)
Pain, Christopher; Xie, Zhihua; Pavlidis, Dimitrios; Salinas, Pablo; Matar, Omar
2016-11-01
Falling liquid films down an inclined or vertical surface have rich wave dynamics, often occurring in many industrial applications, such as condensers, evaporators and chemical reactors. There are some numerical studies for falling liquid films, however most of them have focused on two-dimensional falling films or three-dimensional falling films in a periodic domain. The objective of this study is to investigate flow dynamics of fully developed three-dimensional falling films using the Navier-Stokes equations coupled with interface capturing approach. An adaptive unstructured mesh modelling framework is employed here to study this problem, which can modify and adapt unstructured meshes to better represent the underlying physics of multiphase problems and reduce computational effort without sacrificing accuracy. Numerical examples of two-dimensional and three-dimensional falling films in a long domain with different flow conditions are presented and discussed. EPSRC UK Programme Grant MEMPHIS (EP/K003976/1).
Hydrofocusing Bioreactor for Three-Dimensional Cell Culture
NASA Technical Reports Server (NTRS)
Gonda, Steve R.; Spaulding, Glenn F.; Tsao, Yow-Min D.; Flechsig, Scott; Jones, Leslie; Soehnge, Holly
2003-01-01
The hydrodynamic focusing bioreactor (HFB) is a bioreactor system designed for three-dimensional cell culture and tissue-engineering investigations on orbiting spacecraft and in laboratories on Earth. The HFB offers a unique hydrofocusing capability that enables the creation of a low-shear culture environment simultaneously with the "herding" of suspended cells, tissue assemblies, and air bubbles. Under development for use in the Biotechnology Facility on the International Space Station, the HFB has successfully grown large three-dimensional, tissuelike assemblies from anchorage-dependent cells and grown suspension hybridoma cells to high densities. The HFB, based on the principle of hydrodynamic focusing, provides the capability to control the movement of air bubbles and removes them from the bioreactor without degrading the low-shear culture environment or the suspended three-dimensional tissue assemblies. The HFB also provides unparalleled control over the locations of cells and tissues within its bioreactor vessel during operation and sampling.
A Global Star-forming Episode in M31 2-4 Gyr Ago
NASA Astrophysics Data System (ADS)
Williams, Benjamin F.; Dalcanton, Julianne J.; Dolphin, Andrew E.; Weisz, Daniel R.; Lewis, Alexia R.; Lang, Dustin; Bell, Eric F.; Boyer, Martha; Fouesneau, Morgan; Gilbert, Karoline M.; Monachesi, Antonela; Skillman, Evan
2015-06-01
We have identified a major global enhancement of star formation in the inner M31 disk that occurred between 2-4 Gyr ago, producing ˜60% of the stellar mass formed in the past 5 Gyr. The presence of this episode in the inner disk was discovered by modeling the optical resolved star color-magnitude diagrams of low extinction regions in the main disk of M31 (3 < R < 20 kpc) as part of the Panchromatic Hubble Andromeda Treasury. This measurement confirms and extends recent measurements of a widespread star formation enhancement of similar age in the outer disk, suggesting that this burst was both massive and global. Following the galaxy-wide burst, the star formation rate of M31 has significantly declined. We briefly discuss possible causes for these features of the M31 evolutionary history, including interactions with M32, M33, and/or a merger.
A GLOBAL STAR-FORMING EPISODE IN M31 2–4 GYR AGO
Williams, Benjamin F.; Dalcanton, Julianne J.; Weisz, Daniel R.; Lewis, Alexia R. E-mail: jd@astro.washington.edu; and others
2015-06-10
We have identified a major global enhancement of star formation in the inner M31 disk that occurred between 2–4 Gyr ago, producing ∼60% of the stellar mass formed in the past 5 Gyr. The presence of this episode in the inner disk was discovered by modeling the optical resolved star color–magnitude diagrams of low extinction regions in the main disk of M31 (3 < R < 20 kpc) as part of the Panchromatic Hubble Andromeda Treasury. This measurement confirms and extends recent measurements of a widespread star formation enhancement of similar age in the outer disk, suggesting that this burst was both massive and global. Following the galaxy-wide burst, the star formation rate of M31 has significantly declined. We briefly discuss possible causes for these features of the M31 evolutionary history, including interactions with M32, M33, and/or a merger.
The global structure of hot star winds: Constraints from spectropolarimetry
NASA Astrophysics Data System (ADS)
Eversberg, Thomas
2000-11-01
Chapter 1. We present time-series of ultra-high S/N, high resolution spectra of the He II λ 4686 Å emission line in the O4I(n)f supergiant ζ Puppis, the brightest early-type O-star in the sky. These reveal stochastic, variable substructures in the line, which tend to move away from the line-center with time. Similar scaled-up features are well established in the strong winds of Wolf-Rayet stars (the presumed descendants of O stars), where they are explained by outward moving inhomogeneities (e.g., blobs, clumps, shocks) in the winds. If all hot-star winds are clumped like that of ζ Pup, as is plausible, then mass-low rates based on recombination-line intensities will have to be revised downwards. Using a standard `β' velocity law we deduce a value of β = 1.0-1.2 to account for the kinematics of these structures in the wind of ζ Pup. In addition to the small-scale stochastic variations we also find a slow systematic variation of the mean central absorption reversal. Chapter 2. We introduce a new polarimeter unit which, mounted at the Cassegrain focus of any telescope and fiber-connected to a fixed CCD spectrograph, is able to measure all Stokes parameters I, Q, U and V across spectral lines of bright stellar targets and other point sources in a quasi-simultaneous manner. Applying standard reduction techniques for linearly and circularly polarized light we are able to obtain photon-noise limited line polarization. We briefly outline the technical design of the polarimeter unit and the linear algebraic Mueller calculus for obtaining polarization parameters of any point source. In addition, practical limitations of the optical elements are outlined. We present first results obtained with our spectropolarimeter for four bright, hot-star targets: We confirm previous results for Hα in the bright Be star γ Cas and find linear depolarization features across the emission line complex C III/C IV (λ 5696/λ 5808 Å) of the WR+O binary γ2 Vel. We also find circular
Location of snipers using three-dimensional infrared/laser tracking
NASA Astrophysics Data System (ADS)
Squire, Mark D.
1997-02-01
We present a summary of the top level design of and recent imagery and analysis made with components of the TTC fast infrared sniper tracker (FIRST) system. The FIRST instrument will utilize a 7 cm aperture optical system, a 3 - 5 micron imaging camera, and a pulsed, eye-safe laser radar in order to detect, track, and range upon high angular velocity targets, especially bullets. The optical system is based on an ultra low inertia, high acceleration gimbal which enables large area step and star bullet detection at high coverage rates. Three dimensional track files generated by the FIRST system will be used to accurately back-project to the bullet's origin.
Three-dimensional analysis of partially open butterfly valve flows
Huang, C.; Kim, R.H.
1996-09-01
A numerical simulation of butterfly valve flows is a useful technique to investigate the physical phenomena of the flow field. A three-dimensional numerical analysis was carried out on incompressible fluid flows in a butterfly valve by using FLUENT, which solves difference equations. Characteristics of the butterfly valve flows at different valve disk angles with a uniform incoming velocity were investigated. Comparisons of FLUENT results with other results, i.e., experimental results, were made to determine the accuracy of the employed method. Results of the three-dimensional analysis may be useful in the valve design.
Three-dimensional ultrasonography in hepatobiliary and pancreatic diseases.
Sackmann, M; Pauletzki, J; Zwiebel, F M; Holl, J
1994-06-01
Three-dimensional reconstruction of ultrasonographic images was used to visualize hepatobiliary and pancreatic lesions and stones, and to measure gallbladder emptying. The initial experience shows that these reconstructions may be of some help in the identification of the extension of tumors and the invasion into surrounding tissues. Stones and stone fragments in the pancreas and in the gallbladder as well as the wall of the gallbladder were visualized well. If further studies will reveal a benefit for the patient, three-dimensional ultrasonography may be added to the noninvasive methods used in the diagnosis of several hepatobiliary and pancreatic diseases.
Three-Dimensional Prints with Pinned Cylindrical Lens Arrays
NASA Astrophysics Data System (ADS)
Yasuda, Shin; Shimizu, Keishi
2013-09-01
An application of pinned cylindrical lens arrays (CLAs) reported in Opt. Rev. 19 (2012) 287 to three-dimensional prints is presented for the first time. This lens fabrication method features the easy control of the pitch and radius of curvature of the lens arrays by taking advantage of the pinning effect that the partition walls created on a polymeric substrate by scratching with a cutter blade prevent the ultraviolet curable polymer dispensed between the walls from spreading. It is demonstrated in this paper that a three-dimensional print was realized successfully with the pinned CLA fabricated with our method.
Bootstrapping Critical Ising Model on Three Dimensional Real Projective Space.
Nakayama, Yu
2016-04-08
Given conformal data on a flat Euclidean space, we use crosscap conformal bootstrap equations to numerically solve the Lee-Yang model as well as the critical Ising model on a three dimensional real projective space. We check the rapid convergence of our bootstrap program in two dimensions from the exact solutions available. Based on the comparison, we estimate that our systematic error on the numerically solved one-point functions of the critical Ising model on a three dimensional real projective space is less than 1%. Our method opens up a novel way to solve conformal field theories on nontrivial geometries.
Simulation of Three-Dimensional Positive Photoresist Images
NASA Astrophysics Data System (ADS)
Barouch, E.; Bradie, B.; Babu, S. V.
1989-12-01
The least-action dissolution algorithm (LEAD) is applied to simulate three-dimensional positive photoresist images on reflective substrates. This algorithm avoids the ambiguities of the string algorithm and its modifications by utilizing the local validity of the eikonal description of the underlying diffusion equation to describe developer penetration with a moving boundary. The electric field and the concentration of the photoactive compound (PAC) within the photoresist film in the presence of standing waves in three dimensions are obtained from the numerically efficient WKB procedure proposed recently. The PAC concentration profile is combined with the LEAD algorithm to simulate a three dimensional one micron diameter contact hole in a single layer resist.
Structure of turbulence in three-dimensional boundary layers
NASA Technical Reports Server (NTRS)
Subramanian, Chelakara S.
1993-01-01
This report provides an overview of the three dimensional turbulent boundary layer concepts and of the currently available experimental information for their turbulence modeling. It is found that more reliable turbulence data, especially of the Reynolds stress transport terms, is needed to improve the existing modeling capabilities. An experiment is proposed to study the three dimensional boundary layer formed by a 'sink flow' in a fully developed two dimensional turbulent boundary layer. Also, the mean and turbulence field measurement procedure using a three component laser Doppler velocimeter is described.
Three Dimensional Imaging with Multiple Wavelength Speckle Interferometry
Bernacki, Bruce E.; Cannon, Bret D.; Schiffern, John T.; Mendoza, Albert
2014-05-28
We present the design, modeling, construction, and results of a three-dimensional imager based upon multiple-wavelength speckle interferometry. A surface under test is illuminated with tunable laser light in a Michelson interferometer configuration while a speckled image is acquired at each laser frequency step. The resulting hypercube is Fourier transformed in the frequency dimension and the beat frequencies that result map the relative offsets of surface features. Synthetic wavelengths resulting from the laser tuning can probe features ranging from 18 microns to hundreds of millimeters. Three dimensional images will be presented along with modeling results.
Three-dimensional external flow computations using prismatic grid
NASA Astrophysics Data System (ADS)
Nakahashi, Kazuhiro
1992-12-01
A new approach to compute external viscous flows around three dimensional configurations is proposed. A prismatic grid is used where the three dimensional surface is covered by triangles similar to the unstructured grid. The direction away from the body surface is structured so as to achieve efficient and accurate computations for high Reynolds number viscous flows. The prismatic grid is generated by a newly developed marching-type procedure in which grid spacings are controlled by a variational method. The capability of the method is demonstrated by applying it to a viscous flow computation around a complete aircraft configuration.
A system of three-dimensional complex variables
NASA Technical Reports Server (NTRS)
Martin, E. Dale
1986-01-01
Some results of a new theory of multidimensional complex variables are reported, including analytic functions of a three-dimensional (3-D) complex variable. Three-dimensional complex numbers are defined, including vector properties and rules of multiplication. The necessary conditions for a function of a 3-D variable to be analytic are given and shown to be analogous to the 2-D Cauchy-Riemann equations. A simple example also demonstrates the analogy between the newly defined 3-D complex velocity and 3-D complex potential and the corresponding ordinary complex velocity and complex potential in two dimensions.
Three-dimensional standing waves in a microwave oven
NASA Astrophysics Data System (ADS)
Kamol, S.; Limsuwan, P.; Onreabroy, W.
2010-05-01
A microwave oven operating at a frequency of 2.45 GHz was designed for demonstrating three-dimensional standing waves. The three-dimensional standing wave patterns formed on cobalt chloride paper placed at the center of the oven chamber were examined. The images on the cobalt chloride paper corresponding to antinodes of the standing waves were recorded by a digital camera after turning on the microwave oven. The results show that the numbers of antinodes of the standing waves in each plane agree with those of the theoretical calculation of the electric field distribution in the oven chamber.
Novel multipole Wien filter as three-dimensional spin manipulator
Yasue, T. Suzuki, M.; Koshikawa, T.; Tsuno, K.; Goto, S.; Arai, Y.
2014-04-15
Spin polarized electron beam is often used in material characterizations which relates to magnetism as well as in the high energy particle physics. The manipulation of the spin polarization toward the arbitrary direction is indispensable in such studies. In the present work, a novel multipole Wien filter is proposed as the three-dimensional spin manipulator, and a prototype 8-pole Wien filter is developed. It is applied to spin polarized low energy electron microscopy, and the variation of the magnetic contrast with managing the spin polarization is evaluated. It is confirmed that the novel multipole Wien filter can manipulate the spin polarization three-dimensionally.
Three-dimensional structural analysis using interactive graphics
NASA Technical Reports Server (NTRS)
Biffle, J.; Sumlin, H. A.
1975-01-01
The application of computer interactive graphics to three-dimensional structural analysis was described, with emphasis on the following aspects: (1) structural analysis, and (2) generation and checking of input data and examination of the large volume of output data (stresses, displacements, velocities, accelerations). Handling of three-dimensional input processing with a special MESH3D computer program was explained. Similarly, a special code PLTZ may be used to perform all the needed tasks for output processing from a finite element code. Examples were illustrated.
A class of auxetic three-dimensional lattices
NASA Astrophysics Data System (ADS)
Cabras, Luigi; Brun, Michele
2016-06-01
We propose a class of auxetic three-dimensional lattice structures. The elastic microstructure can be designed to have an omnidirectional Poisson's ratio arbitrarily close to the stability limit of -1. The cubic behaviour of the periodic system has been fully characterized; the minimum and maximum Poisson's ratio and the associated principal directions are given as a function of the microstructural parameters. The initial microstructure is then modified into a body-centred cubic system that can achieve Poisson's ratio lower than -1 and that can also behave as an isotropic three-dimensional auxetic structure.
Microperiodic structures: direct writing of three-dimensional webs.
Gratson, Gregory M; Xu, Mingjie; Lewis, Jennifer A
2004-03-25
Applications are emerging that require the creation of fine-scale structures in three dimensions--examples include scaffolds for tissue engineering, micro-fluidic devices and photonic materials that control light propagation over a range of frequencies. But writing methods such as dip-pen nanolithography and ink-jet printing are either confined to two dimensions or beset by wetting and spreading problems. Here we use concentrated polyelectrolyte inks to write three-dimensional microperiodic structures directly without using masks. Our technique enables us to write arbitrary three-dimensional patterns whose features are nearly two orders of magnitude smaller than those attained with other multilayer printing techniques.
Three-dimensional boron particle loaded thermal neutron detector
Nikolic, Rebecca J.; Conway, Adam M.; Graff, Robert T.; Kuntz, Joshua D.; Reinhardt, Catherine; Voss, Lars F.; Cheung, Chin Li; Heineck, Daniel
2014-09-09
Three-dimensional boron particle loaded thermal neutron detectors utilize neutron sensitive conversion materials in the form of nano-powders and micro-sized particles, as opposed to thin films, suspensions, paraffin, etc. More specifically, methods to infiltrate, intersperse and embed the neutron nano-powders to form two-dimensional and/or three-dimensional charge sensitive platforms are specified. The use of nano-powders enables conformal contact with the entire charge-collecting structure regardless of its shape or configuration.
Radiative Instabilities in Three-Dimensional Astrophysical Masers
NASA Technical Reports Server (NTRS)
Scappaticci, Gerardo A.; Watson, William D.
1995-01-01
Inherent instabilities in the radiative transfer for astrophysical masers have been recognized and calculated in the linear maser idealization in our previous investigations. The same instabilities are now shown to occur in the more realistic, three-dimensional geometries. Fluctuations in the emergent flux result and may be related to the observed fluctuations in the radiative flux from the 1665 MHz OH masers that have been reported to occur on timescales as short as 1000 s. The time-dependent differential equations of radiative transfer are solved numerically for three-dimensional astrophysical masers. Computations are performed for spherical and elongated (rectangular parallelepiped) geometries.
Binary Colloidal Alloy Test-5: Three-Dimensional Melt
NASA Technical Reports Server (NTRS)
Yodh, Arjun G.
2008-01-01
Binary Colloidal Alloy Test - 5: Three-Dimensional Melt (BCAT-5-3DMelt) photographs initially randomized colloidal samples in microgravity to determine their resulting structure over time. BCAT-5-3D-Melt will allow the scientists to capture the kinetics (evolution) of their samples, as well as the final equilibrium state of each sample. BCAT-5-3D-Melt will look at the mechanisms of melting using three-dimensional temperature sensitive colloidal crystals. Results will help scientists develop fundamental physics concepts previously shadowed by the effects of gravity.
Applications of three-dimensionally scanned models in orthodontics.
Cha, B K; Choi, J I; Jost-Brinkmann, P G; Jeong, Y M
2007-01-01
The purpose of this study was to investigate clinical applications of the three-dimensional reverse engineering technologies for the analysis of orthodontic models. The measuring accuracy and the process of the 3D model scanning technique were evaluated with respect to linear, surface and volumetric parameters. Orthodontically induced dentoalveolar changes, which have been traditionally evaluated by cephalometric analysis, were assessed by the registration function of Rapidform 2002, a 3D-reverse modeling software in scanned maxillary casts. Three-dimensional digital models are valuable alternatives to conventional casts for model analysis and also yield information which could previously be gathered only by cephalometric superimposition.
NASA Astrophysics Data System (ADS)
Fenton, Flavio H.; Evans, Steven J.; Hastings, Harold M.; Cherry, Elizabeth M.
2006-03-01
Presentation and analysis of large three-dimensional data sets is in general hard to do using only two-dimensional figures and plots. In this talk, we will demonstrate techniques for illustrating static and dynamic three-dimensional objects and data using Virtual Reality Modeling Language (VRML) as well as Java. The advantage of these two languages is that they are platform-independent, which allows for easy sharing of data and visualizations. In addition, manipulation of data is relatively easy as rotation, translation and zooming can be done in real- time for static objects as well as for data and objects that vary and deform in time. Examples of fully three-dimensional movies will be shown, including dendritic growth and propagation of electrical waves in cardiac tissue. In addition, we will show how to include VRML and Java viewers in PowerPoint for easy presentation of results in classes and seminars.
Global and radial variations in the efficiency of massive star formation among galaxies
NASA Technical Reports Server (NTRS)
Allen, Lori E.; Young, Judith S.
1990-01-01
In order to determine the regions within galaxies which give rise to the most efficient star formation and to test the hypothesis that galaxies with high infrared luminosities per unit molecular mass are efficiently producing high mass stars, researchers have undertaken an H alpha imaging survey in galaxies whose CO distributions have been measured as part of the Five College Radio Astronomy Observatory (FCRAO) Extragalactic CO Survey. From these images researchers have derived global H alpha fluxes and distributions for comparison with far infrared radiation (FIR) fluxes and CO fluxes and distributions. Here, researchers present results on the global massive star formation efficiency (SFE = L sub H sub alpha/M(H2)) as a function of morphological type and environment, and on the radial distribution of the SFE within both peculiar and isolated galaxies. On the basis of comparison of the global L sub H sub alpha/M(H2) and L sub FIR/M(H2) for 111 galaxies, researchers conclude that environment rather than morphological type has the strongest effect on the global efficiency of massive star formation. Based on their study of a small sample, they find that the largest radial gradients are observed in the interacting/peculiar galaxies, indicating that environment affects the star formation efficiency within galaxies as well.
Development of Three-Dimensional Completion of Complex Objects
ERIC Educational Resources Information Center
Soska, Kasey C.; Johnson, Scott P.
2013-01-01
Three-dimensional (3D) object completion, the ability to perceive the backs of objects seen from a single viewpoint, emerges at around 6 months of age. Yet, only relatively simple 3D objects have been used in assessing its development. This study examined infants' 3D object completion when presented with more complex stimuli. Infants…
Algebraic Ricci solitons of three-dimensional Lorentzian Lie groups
NASA Astrophysics Data System (ADS)
Batat, W.; Onda, K.
2017-04-01
We study algebraic Ricci solitons of three-dimensional Lorentzian Lie groups. All algebraic Ricci solitons that we obtain are solvsolitons. In particular, we obtain new solitons on G2, G5, and G6, and we prove that, contrary to the Riemannian case, Lorentzian Ricci solitons need not be algebraic Ricci solitons.
Three-Dimensional Extension of a Digital Library Service System
ERIC Educational Resources Information Center
Xiao, Long
2010-01-01
Purpose: The paper aims to provide an overall methodology and case study for the innovation and extension of a digital library, especially the service system. Design/methodology/approach: Based on the three-dimensional structure theory of the information service industry, this paper combines a comprehensive analysis with the practical experiences…
Three-dimensional cell to tissue development process
NASA Technical Reports Server (NTRS)
Goodwin, Thomas J. (Inventor); Parker, Clayton R. (Inventor)
2008-01-01
An improved three-dimensional cell to tissue development process using a specific time varying electromagnetic force, pulsed, square wave, with minimum fluid shear stress, freedom for 3-dimensional spatial orientation of the suspended particles and localization of particles with differing or similar sedimentation properties in a similar spatial region.
Polyimide Aerogels with Three-Dimensional Cross-Linked Structure
NASA Technical Reports Server (NTRS)
Meador, Mary Ann B. (Inventor)
2016-01-01
A method for creating a three dimensional cross-linked polyimide structure includes dissolving a diamine, a dianhydride, and a triamine in a solvent, imidizing a polyamic acid gel by heating the gel, extracting the gel in a second solvent, supercritically drying the gel, and removing the solvent to create a polyimide aerogel.
Three-dimensional acousto-optic spectrum analysis
NASA Technical Reports Server (NTRS)
Ansari, Homayoon; Metscher, Brian; Lesh, James R.
1990-01-01
A three-dimensional acoustooptic spectrum analyzer with subhertz resolution is demonstrated experimentally. The first and second dimensions are the two spatial dimensions of the output detector array, and the third dimension is time as sampled by the detector array frame rate. A superfine resolution of 0.12 Hz has been achieved.
Interactive Multimedia and Concrete Three-Dimensional Modelling.
ERIC Educational Resources Information Center
Baxter, J. H.; Preece, Peter F. W.
1999-01-01
Compares a multimedia package for teaching about the phases of the moon to grade 8 (12-year-old) students with a conventional three-dimensional modeling approach. Results show both methods were equally effective in terms of student learning, for male and female students, and prior computer experience was not a factor in multimedia use. (Author/LRW)
Speed and pressure recording in three-dimensional flow
NASA Technical Reports Server (NTRS)
Krisam, F
1932-01-01
Van der Megge Zijnen's spherical Pitot tube with its 5 test holes insures a simultaneous record of static pressure and magnitude and direction of velocity in three-dimensional flow. The report treats the method as well as the range of application of this Pitot in the light of modern knowledge on flow around spheres.
Three-Dimensional Interactive Design Using Bezier Curves and Surfaces.
ERIC Educational Resources Information Center
Khonsari, M. M.; Horn, D.
1987-01-01
Offers a method for interactive design of objects on a computer. Outlines a method which allows the designer to interact with orthogonal views to construct a three dimensional model of an arbitrary shape. Presents an algorithm based on the Bezier curves to efficiently create smooth curves and surfaces. (CW)
Three-Dimensional Space to Assess Cloud Interoperability
2013-03-01
major cloud providers, OpenStack and OpeNebula, to demonstrate the usage of the three-dimensional space and its benefits . We start this chapter with a...documentation:rel4.0:external_auth. [68] X. Gao, P. Shah, A. Yoga , A. Kodgire and X. Ni. Cloud storage survey [Online]. Available: http
Three-dimensional measurements of fatigue crack closure
NASA Technical Reports Server (NTRS)
Ray, S. K.; Grandt, A. F., Jr.
1984-01-01
Fatigue crack growth and retardation experiments conducted in polycarbonate test specimen are described. The transparent test material allows optical interferometry measurements of the fatigue crack opening (and closing) profiles. Crack surface displacements are obtained through the specimen thickness and three dimensional aspects of fatigue crack closure are discussed.
Numerical investigations in three-dimensional internal flows
NASA Technical Reports Server (NTRS)
Rose, William C.
1990-01-01
The flow in the transonic test facility was investigated using the three dimensional computational fluid dynamics techniques. The application of the full Navier-Stokes three dimensional code to the flow qualities in the contraction section of transonic wind tunnel is discussed. Initially, two dimensional solutions indicated the possibility for large secondary flow to exist as a result of the asymmetries involved in the contraction section as it is constructed. The results of a full three dimensional solution indicate that only minor pressure variations actually occur in the contraction section within any given cross flow plane. Further analysis of the three dimensional solution indicated that these slight lateral pressure gradients lead to negligible secondary flows, except within a small region in the corners within the boundary layer. On the basis of present solution, it would not be expected that any flow asymmetries and/or secondary flow present within contraction section are associated with the methods by which the contraction is implemented in its present configuration.
Three-dimensional shallow water system: A relaxation approach
NASA Astrophysics Data System (ADS)
Liu, Xin; Mohammadian, Abdolmajid; Infante Sedano, Julio Ángel; Kurganov, Alexander
2017-03-01
We study a three-dimensional shallow water system, which is obtained from the three-dimensional Navier-Stokes equations after Reynolds averaging and under the simplifying hydrostatic pressure assumption. Since the three-dimensional shallow water system is generically not hyperbolic, it cannot be numerically solved using hyperbolic shock capturing schemes. At the same time, existing simple finite-difference and finite-volume methods may fail in simulations of unsteady flows with sharp gradients, such as dam-break and flood flows. To overcome this limitation, we propose a novel numerical method, which is based on a relaxation approach utilized to "hyperbolize" the three-dimensional shallow water system. The extended relaxation system is hyperbolic and we develop a second-order semi-discrete central-upwind scheme for it. The proposed numerical method can preserve "lake at rest" steady states and positivity of water depth over irregular bottom topography. The accuracy, stability and robustness of the developed numerical method is verified on five numerical experiments.
Three-dimensional ultrasound imaging of the vasculature.
Fenster, A; Lee, D; Sherebrin, S; Rankin, R; Downey, D
1998-02-01
With conventional ultrasonography, the diagnostician must view a series of two-dimensional images in order to form a mental impression of the three-dimensional anatomy, an efficient and time consuming practice prone to operator variability, which may cause variable or even incorrect diagnoses. Also, a conventional two-dimensional ultrasound image represents a thin slice of the patients anatomy at a single location and orientation, which is difficult to reproduce at a later time. These factors make conventional ultrasonography non-optimal for prospective or follow-up studies. Our efforts have focused on overcoming these deficiencies by developing three-dimensional ultrasound imaging techniques that are capable of acquiring B-mode, colour Doppler and power Doppler images of the vasculature, by using a conventional ultrasound system to acquire a series of two-dimensional images and then mathematically reconstructing them into a single three-dimensional image, which may then be viewed interactively on an inexpensive desktop computer. We report here on two approaches: (1) free-hand scanning, in which a magnetic positioning device is attached to the ultrasound transducer to record the position and orientation of each two-dimensional image needed for the three-dimensional image reconstruction; and (2) mechanical scanning, in which a motor-driven assembly is used to translate the transducer linearly across the neck, yielding a set of uniformly-spaced parallel two-dimensional images.
Assembly of Viral Hydrogels for Three-Dimensional Conducting Nanocomposites
Chen, Po-Yen; Hyder, Md Nasim; Mackanic, David; Courchesne, Noémie-Manuelle Dorval; Qi, Jifa
2014-01-01
M13 bacteriophages act as versatile scaffolds capable of organizing single-walled carbon nanotubes and fabricating three-dimensional conducting nanocomposites. The morphological, electrical, and electrochemical properties of the nanocomposites are presented, as well as its ability to disperse and utilize single-walled carbon nanotubes effectively. PMID:24782428
Computer Generated Holography as a Three-Dimensional Display Medium
1990-12-01
series of two dimensional images are reflected on an object screen resulting in an autostereoscopic , or true three dimensional, images. The advantages of...an attractive target to optimize. Jack Ritter has suggested a fast approximation to 3D Euclidean distance calculations (10:432). His methid uses no
Potential Flows From Three-Dimensional Complex Variables
NASA Technical Reports Server (NTRS)
Martin, E. Dale; Kelly, Patrick H.; Panton, Ronald L.
1992-01-01
Report presents investigation of several functions of three-dimensional complex variable, with emphasis on potential-flow fields computed from these functions. Part of continuing research on generalization of well-established two-dimensional complex analysis to three and more dimensions.
View Factor Calculation for Three-Dimensional Geometries.
1989-06-20
Version 00 MCVIEW calculates the radiation geometric view factor between surfaces for three dimensional geometries with and without interposed third surface obstructions. It was developed to calculate view factors for input data to heat transfer analysis programs such as SCA-03/TRUMP, SCA-01/HEATING-5 and PSR-199/HEATING-6.
Two-Dimensional Chirality in Three-Dimensional Chemistry.
ERIC Educational Resources Information Center
Wintner, Claude E.
1983-01-01
The concept of two-dimensional chirality is used to enhance students' understanding of three-dimensional stereochemistry. This chirality is used as a key to teaching/understanding such concepts as enaniotropism, diastereotopism, pseudoasymmetry, retention/inversion of configuration, and stereochemical results of addition to double bonds. (JN)
Three dimensional boundary layers on submarine conning towers and rudders
NASA Astrophysics Data System (ADS)
Gleyzes, C.
1988-01-01
Solutions for the definition of grids adapted to the calculation of three-dimensional boundary layers on submarine conning towers and on submarine rudders and fins are described. The particular geometry of such bodies (oblique shaped hull, curved fins) required special adaptations. The grids were verified on examples from a test basin.
Constructing Mental Representations of Complex Three-Dimensional Objects.
ERIC Educational Resources Information Center
Aust, Ronald
This exploratory study investigated whether there are differences between males and females in the strategies used to construct mental representations from three-dimensional objects in a dimensional travel display. A Silicon Graphics IRIS computer was used to create the travel displays and mathematical models were created for each of the objects…
A three dimensional calculation of elastic equilibrium for composite materials
NASA Technical Reports Server (NTRS)
Lustman, Liviu R.; Rose, Milton E.
1986-01-01
A compact scheme is applied to three-dimensional elasticity problems for composite materials, involving simple geometries. The mathematical aspects of this approach are discussed, in particular the iteration method. A vector processor code implementing the compact scheme is presented, and several numerical experiments are summarized.
Three-dimensional AOTV flowfields in chemical nonequilibrium
NASA Technical Reports Server (NTRS)
Gnoffo, P. A.; Mccandless, R. S.
1986-01-01
A technique for upwind differencing of the three-dimensional species continuity equations is presented which permits computation of steady flows in chemical equilibrium and nonequilibrium. The capabilities and shortcomings of the present approach for equilibrium and nonequilibrium flows is discussed. Modifications now being investigated to improve computational time are outlined.
Modern cosmology and the origin of our three dimensionality.
Woodbury, M A; Woodbury, M F
1998-01-01
We are three dimensional egocentric beings existing within a specific space/time continuum and dimensionality which we assume wrongly is the same for all times and places throughout the entire universe. Physicists name Omnipoint the origin of the universe at Dimension zero, which exploded as a Big Bang of energy proceeding at enormous speed along one dimension which eventually curled up into matter: particles, atoms, molecules and Galaxies which exist in two dimensional space. Finally from matter spread throughout the cosmos evolved life generating eventually the DNA molecules which control the construction of brains complex enough to construct our three dimensional Body Representation from which is extrapolated what we perceive as a 3-D universe. The whole interconnected structures which conjure up our three dimensionality are as fragile as Humpty Dumpty, capable of breaking apart with terrifying effects for the individual patient during a psychotic panic, revealing our three dimensionality to be but "maya", an illusion, which we psychiatrists work at putting back together.
THREE-DIMENSIONAL NAPL FATE AND TRANSPORT MODEL
We have added several new and significant capabilities to UTCHEM to make it into a general-purpose NAPL simulator. The simulator is now capable of modeling transient and steady-state three-dimensional flow and mass transport in the groundwater (saturated) and vadose (unsaturated...
A Three-Dimensional Haptic Matrix Test of Nonverbal Reasoning
ERIC Educational Resources Information Center
Miller, Joseph C.; Skillman, Gemma D.; Benedetto, Joanne M.; Holtz, Ann M.; Nassif, Carrie L.; Weber, Anh D.
2007-01-01
Three-dimensional haptic matrices were pilot-tested as a nonvisual measure of cognitive ability. The results indicated that they correlated with convergent measures, with emphasis on spatial processing and that the participants who described items "visually" completed them more quickly and accurately and tended to have become visually…
Three-Dimensional Printing Using a Photoinitiated Polymer
ERIC Educational Resources Information Center
Muskin, Joseph; Ragusa, Matthew; Gelsthorpe, Thomas
2010-01-01
Printers capable of producing three-dimensional objects are becoming more common. Most of these printers are impractical for use in the chemistry classroom because of the expense incurred in fabricating a print head that must be controlled in three dimensions. We propose a simpler solution to this problem that allows the emerging technology of…
Heat engine in the three-dimensional spacetime
NASA Astrophysics Data System (ADS)
Mo, Jie-Xiong; Liang, Feng; Li, Gu-Qiang
2017-03-01
We define a kind of heat engine via three-dimensional charged BTZ black holes. This case is quite subtle and needs to be more careful. The heat flow along the isochores does not equal to zero since the specific heat C V ≠ 0 and this point completely differs from the cases discussed before whose isochores and adiabats are identical. So one cannot simply apply the paradigm in the former literatures. However, if one introduces a new thermodynamic parameter associated with the renormalization length scale, the above problem can be solved. We obtain the analytical efficiency expression of the three-dimensional charged BTZ black hole heat engine for two different schemes. Moreover, we double check with the exact formula. Our result presents the first specific example for the sound correctness of the exact efficiency formula. We argue that the three-dimensional charged BTZ black hole can be viewed as a toy model for further investigation of holographic heat engine. Furthermore, we compare our result with that of the Carnot cycle and extend the former result to three-dimensional spacetime. In this sense, the result in this paper would be complementary to those obtained in four-dimensional spacetime or ever higher. Last but not the least, the heat engine efficiency discussed in this paper may serve as a criterion to discriminate the two thermodynamic approaches introduced in ref. [29] and our result seems to support the approach which introduces a new thermodynamic parameter R = r 0 .
Development of Three-Dimensional Object Completion in Infancy
ERIC Educational Resources Information Center
Soska, Kasey C.; Johnson, Scott P.
2008-01-01
Three-dimensional (3D) object completion was investigated by habituating 4- and 6-month-old infants (n = 24 total) with a computer-generated wedge stimulus that pivoted 15[degrees], providing only a limited view. Two displays, rotating 360[degrees], were then shown: a complete, solid volume and an incomplete, hollow form composed only of the sides…
Three dimensional flow measurements in a turbine scroll
NASA Technical Reports Server (NTRS)
Tabakoff, W.; Vittal, B. V. R.; Wood, B.
1982-01-01
A study was conducted to determine experimentally the flow behavior in combined scroll nozzle assembly of a radial inflow turbine. Hot film anemometry technique was used to measure the three dimensional flow velocity in the scroll. The through flow and secondary flow velocity components are measured at various points in three scroll sections.
High three dimensional thermoelectric performance from low dimensional bands
Singh, David J; Chen, Xin; Parker, David S
2013-01-01
Reduced dimensionality has long been regarded as an important strategy for increasing thermoelectric performance, for example in superlattices and other engineered structures. Here we point out and illustrate by examples that three dimensional bulk materials can be made to behave as if they were two dimensional from the point of view of thermoelectric performance. Implications for the discovery of new practical thermoelectrics are discussed.
A Novel Three-Dimensional Tool for Teaching Human Neuroanatomy
ERIC Educational Resources Information Center
Estevez, Maureen E.; Lindgren, Kristen A.; Bergethon, Peter R.
2010-01-01
Three-dimensional (3D) visualization of neuroanatomy can be challenging for medical students. This knowledge is essential in order for students to correlate cross-sectional neuroanatomy and whole brain specimens within neuroscience curricula and to interpret clinical and radiological information as clinicians or researchers. This study implemented…
Quantum field between moving mirrors: A three dimensional example
NASA Technical Reports Server (NTRS)
Hacyan, S.; Jauregui, Roco; Villarreal, Carlos
1995-01-01
The scalar quantum field uniformly moving plates in three dimensional space is studied. Field equations for Dirichlet boundary conditions are solved exactly. Comparison of the resulting wavefunctions with their instantaneous static counterpart is performed via Bogolubov coefficients. Unlike the one dimensional problem, 'particle' creation as well as squeezing may occur. The time dependent Casimir energy is also evaluated.
Three-Dimensional Printing: A Journey in Visualization
ERIC Educational Resources Information Center
Poetzel, Adam; Muskin, Joseph; Munroe, Anne; Russell, Craig
2012-01-01
Imagine high school students glued to computer screens--not playing video games but applying their mathematical knowledge of functions to the design of three-dimensional sculptures. Imagine these students engaging in rich discourse as they transform functions of their choosing to design unique creations. Now, imagine these students using…
THREE-DIMENSIONAL TEACHING AIDS FOR TRADE AND INDUSTRIAL INSTRUCTION.
ERIC Educational Resources Information Center
ROSENGREN, HAROLD J.
THREE-DIMENSIONAL MODELS ARE USED WITH GREAT EFFECTIVENESS AS TEACHING AIDS. CONCEPTS CAN BE MUCH MORE READILY UNDERSTOOD WHEN SIGNIFICANT RELATIONSHIPS AND IDEAS ARE SIMPLIFIED, EXAGGERATED, AND PRESENTED AS WORKING MODELS. THESE MODELS CAN BE CONSTRUCTED BY TEACHERS AND/OR STUDENTS. THE FOLLOWING CONSIDERATIONS SHOULD BE KEPT IN MIND--THE AID…
Three-dimensional coupled mode analysis of internal-wave acoustic ducts.
Shmelev, Alexey A; Lynch, James F; Lin, Ying-Tsong; Schmidt, Henrik
2014-05-01
A fully three-dimensional coupled mode approach is used in this paper to describe the physics of low frequency acoustic signals propagating through a train of internal waves at an arbitrary azimuth. A three layer model of the shallow water waveguide is employed for studying the properties of normal modes and their coupled interaction due to the presence of nonlinear internal waves. Using a robust wave number integration technique for Fourier transform computation and a direct global matrix approach, an accurate three-dimensional coupled mode full field solution is obtained for the tonal signal propagation through straight and parallel internal waves. This approach provides accurate results for arbitrary azimuth and includes the effects of backscattering. This enables one to provide an azimuthal analysis of acoustic propagation and separate the effects of mode coupled transparent resonance, horizontal reflection and refraction, the horizontal Lloyd's mirror, horizontal ducting and anti-ducting, and horizontal tunneling and secondary ducting.
Three-dimensional flows about simple components at angle of attack
NASA Technical Reports Server (NTRS)
Peake, D. J.; Tobak, M.
1982-01-01
The structures of three dimensional separated flow about some chosen aerodynamic components at angle of attack are synthesized, holding strictly to the notion that streamlines in the external flow (viscous plus inviscid) and skin friction lines on the body surface may be considered as trajectories having properties consistent with those of continuous vector fields. Singular points in the fields are of limited number and are classified as simple nodes and saddles. Analogous flow structures at high angles of attack about blunt and pointed bodies, straight and swept wings, etc., are discussed, highlighting the formation of spiral nodes (foci) in the pattern of the skin friction lines. How local and global three dimensional separation lines originate and form is addressed, and the characteristics of both symmetric and asymmetric leeward wakes are described.
Three-dimensional dynamic response analysis of earth dams
Mejia, L.H.
1981-01-01
The purpose of the present work has been to develop numerical techniques for the three-dimensional dynamic analysis of earth and rockfill dams and to study the dynamic behavior of embankment dams in three dimensions. A computer program suitable for the three-dimensional dynamic response analysis of earth dams was used to back-calculate the dynamic material properties of Oroville Dam from the recorded response of the dam to the August 1, 1975 Oroville earthquake. The dynamic response characteristics of earth dams which exhibit considerable three-dimensional behavior have been studied and the applicability of two-dimensional analysis to the computation of the dynamic response of such structures has been evaluated. Additionally, the effects that the degree of discretization in the cross-valley direction has on the computed three-dimensional dynamic response of earth dams have been studied. A K/sub 2/max value of 170 was found to be representative of the in-situ dynamic characteristics of the Oroville gravels. The three-dimensional effects of canyon geometry on the dynamic response of dams in triangular canyons were found to depend on the crest length to height ratio, L/H, of the dam. For dams with L/H greater than 7, these effects are small. The dynamic characteristics of these dams can, therefore, be simulated reasonably well using two-dimensional analyses. However, 2-D analyses cannot simulate correctly the dynamic response of dams in narrower canyons since the effects of canyon geometry for these dams are very pronounced.
Geroux, Christopher M.; Deupree, Robert G.
2014-03-10
We have developed a multi-dimensional radiation hydrodynamics code to simulate the interaction of radial stellar pulsation and convection for full-amplitude pulsating models. Convection is computed using large eddy simulations. Here, we perform three-dimensional (3D) simulations of RR Lyrae stars for comparison with previously reported 2D simulations. We find that the time-dependent behavior of the peak convective flux on pulsation phase is very similar in both the 2D and 3D calculations. The growth rates of the pulsation in the 2D calculations are about 0.1% higher than in the 3D calculations. The amplitude of the light curve for a 6500 K RR Lyrae model is essentially the same for our 2D and 3D calculations, as is the rising light curve. There are differences in the slope at various times during falling light.
Three-dimensional density structure of the lunar upper lithosphere
NASA Astrophysics Data System (ADS)
Liang, Q.; Du, J.; Chen, C.; Li, Y.
2011-12-01
The lithosphere of the Moon has a thickness over 1200 km according to the seismology studies. It records the giant impact events during the processes of solidification. The upper lithosphere including the crust and the upper mantle was thought to be a nonuniform layer in thickness and seismic velocity, yet the lateral density structure remains poorly understood. The global gravity data thus provides a significant constraint on the three-dimensional (3-D) density structure of the Moon. Previous studies assumed that the crust and the mantle have constant density the gravity anomalies are only produced by the variations of interface between the crust and the mantle. Therefore, the constant density may give overestimation or underestimation of the Moho depth. In contrast, we apply a 3-D inverse method in spherical coordinate to the lunar gravity anomaly. It is a direct way in recovering the density structures beneath mascon basins or the lateral density heterogeneities in the upper lithosphere. The gravity anomaly we use in this study is the Bouguer gravity anomaly calculated at 1750 km radius relative to the reference radius, 1737.153 km[1], from the newly gravity field model SGM100i[2] and the topography model LRO_LTM02[1]. In order to understand the global feature of density variation, we truncate the long wavelength anomaly up to the order of 30 to reconstruct the density distribution above the depth of 100 km in the Moon. With the inverse technique, we obtain a global 3-D density structure of the lunar lithosphere down to 100 km depth. The major features are dominated by the mascons with dense materials and the broad region of the farside highland with relative low density mass. From this structure, the huge mass concentrations are found beneath the South Pole-Aitken (SPA) basin, meaning that the oblique impact not only excavated the SPA basin into deep but also made the mantle uplifted close to a depth of 30 km (relative to a 1738 km radius). We suggest here that
Three dimensional Monte Carlo simulations of ionized nebulae
NASA Astrophysics Data System (ADS)
Ercolano, Barbara
2002-12-01
The study of photoionized environments is fundamental to many astrophysical problems. Up to the present most photoionization codes have numerically solved the equations of radiative transfer by making the extreme simplifying assumption of spherical symmetry. Unfortunately very few real astronomical nebulae satisfy this requirement. To remedy these shortcomings, a self-consistent, three-dimensional radiative transfer code has been developed using Monte Carlo techniques. The code, Mocassin, is designed to build realistic models of photoionized nebulae having arbitrary geometries and density distributions with both the stellar and diffuse radiation fields treated self-consistently. In addition, the code is capable of treating one or more exciting stars located at non-central locations. The gaseous region is approximated by a cuboidal Cartesian grid composed of numerous cells. The physical conditions within each grid cell are determined by solving the thermal equilibrium and ionization balance equations. This requires a knowledge of the local primary and secondary radiation fields, which are calculated self-consistently by locally simulating the individual processes of ionization and recombination. The main structure and computational methods used in the Mocassin code are described in this thesis. Mocassin has been benchmarked against established one-dimensional spherically symmetric codes for a number of standard cases, as defined by the Lexington/Meudon photoionization workshops (Pequignot, 1986; Ferland et al., 1995; Pequignot et al., 2001). The results obtained for the benchmark cases are satisfactory and are presented in this work. A performance analysis has also been carried out and is discussed here. The code has been applied to construct a realistic model of the planetary nebula NGC 3918. Three different geometric models were tried, the first being the biconical density distribution already used by Clegg et al. (1987). In this model the nebula is approximated
Synergies between Asteroseismology and Three-dimensional Simulations of Stellar Turbulence
NASA Astrophysics Data System (ADS)
Arnett, W. David; Moravveji, E.
2017-02-01
Turbulent mixing of chemical elements by convection has fundamental effects on the evolution of stars. The standard algorithm at present, mixing-length theory (MLT), is intrinsically local, and must be supplemented by extensions with adjustable parameters. As a step toward reducing this arbitrariness, we compare asteroseismically inferred internal structures of two Kepler slowly pulsating B stars (SPBs; M∼ 3.25{M}ȯ ) to predictions of 321D turbulence theory, based upon well-resolved, truly turbulent three-dimensional simulations that include boundary physics absent from MLT. We find promising agreement between the steepness and shapes of the theoretically predicted composition profile outside the convective region in 3D simulations and in asteroseismically constrained composition profiles in the best 1D models of the two SPBs. The structure and motion of the boundary layer, and the generation of waves, are discussed.
Abundance analysis of the halo giant HD 122563 with three-dimensional model stellar atmospheres
NASA Astrophysics Data System (ADS)
Collet, R.; Nordlund, Å.; Asplund, M.; Hayek, W.; Trampedach, R.
We present a preliminary local thermodynamic equilibrium (LTE) abundance analysis of the template halo red giant HD122563 based on a realistic, three-dimensional (3D), time-dependent, hydrodynamical model atmosphere of the very metal-poor star. We compare the results of the 3D analysis with the abundances derived by means of a standard LTE analysis based on a classical, 1D, hydrostatic model atmosphere of the star. Due to the different upper photospheric temperature stratifications predicted by 1D and 3D models, we find large, negative, 3D-1D LTE abundance differences for low-excitation OH and Fe I lines. We also find trends with lower excitation potential in the derived Fe LTE abundances from Fe I lines, in both the 1D and 3D analyses. Such trends may be attributed to the neglected departures from LTE in the spectral line formation calculations.
Slightly two- or three-dimensional self-similar solutions
NASA Astrophysics Data System (ADS)
Sari, Re'em; Bode, Nate; Yalinewich, Almog; MacFadyen, Andrew
2012-08-01
Self-similarity allows for analytic or semi-analytic solutions to many hydrodynamics problems. Most of these solutions are one-dimensional. Using linear perturbation theory, expanded around such a one-dimensional solution, we find self-similar hydrodynamic solutions that are two- or three-dimensional. Since the deviation from a one-dimensional solution is small, we call these slightly two-dimensional and slightly three-dimensional self-similar solutions, respectively. As an example, we treat strong spherical explosions of the second type. A strong explosion propagates into an ideal gas with negligible temperature and density profile of the form ρ(r, θ, ϕ) = r-ω[1 + σF(θ, ϕ)], where ω > 3 and σ ≪ 1. Analytical solutions are obtained by expanding the arbitrary function F(θ, ϕ) in spherical harmonics. We compare our results with two-dimensional numerical simulations, and find good agreement.
Electroencephalographic (EEG) control of three-dimensional movement
NASA Astrophysics Data System (ADS)
McFarland, Dennis J.; Sarnacki, William A.; Wolpaw, Jonathan R.
2010-06-01
Brain-computer interfaces (BCIs) can use brain signals from the scalp (EEG), the cortical surface (ECoG), or within the cortex to restore movement control to people who are paralyzed. Like muscle-based skills, BCIs' use requires activity-dependent adaptations in the brain that maintain stable relationships between the person's intent and the signals that convey it. This study shows that humans can learn over a series of training sessions to use EEG for three-dimensional control. The responsible EEG features are focused topographically on the scalp and spectrally in specific frequency bands. People acquire simultaneous control of three independent signals (one for each dimension) and reach targets in a virtual three-dimensional space. Such BCI control in humans has not been reported previously. The results suggest that with further development noninvasive EEG-based BCIs might control the complex movements of robotic arms or neuroprostheses.
Three-dimensional natural convection in a narrow spherical shell
NASA Astrophysics Data System (ADS)
Liu, Ming; Egbers, Christoph
The convective motions in a shallow fluid layer between two concentric spheres in the presence of a constant axial force field have been studied numerically. The aspect ratio of the fluid layer to inner radius is beta =0.08, the Prandtl number Pra =37.5. A three-dimensional time-dependent numerical code is used to solve the governing equations in primitive variables. Convection in the sphe rical shell has then a highly three-dimensional nature. Characteristic flow patterns with a large number of banana-type cells, oriented in north-south direction and aligned in the azimuthal direction, are formed on the northern hemisphere, which grow gradually into the equatorial region accompanied by the generation of new cells as the Rayleigh number is increased. Various characteristics of these flows as well as their transient evolution are investigated for Rayleigh numbers up to 20 000.
Three-dimensional limaçon: Properties and applications
NASA Astrophysics Data System (ADS)
Kreismann, Jakob; Sinzinger, Stefan; Hentschel, Martina
2017-01-01
We perform electromagnetic wave simulations of fully three-dimensional optical limaçon microcavities, on the basis of their future applications in microlasers and photonic devices. The analysis of the three-dimensional modes and far fields reveals an increase of the quality factors as compared to the two-dimensional case. The structure of the far field in the third dimension shows pronounced maxima in the emission directionality inclined to the resonator plane which may be exploited for coupling the resonator modes to the environment. This triggers ideas for technical applications, such as the suggested sensor that can detect small changes in the environment based on changes in the emission profile.
Artificial three-dimensional niches deconstruct pancreas development in vitro.
Greggio, Chiara; De Franceschi, Filippo; Figueiredo-Larsen, Manuel; Gobaa, Samy; Ranga, Adrian; Semb, Henrik; Lutolf, Matthias; Grapin-Botton, Anne
2013-11-01
In the context of a cellular therapy for diabetes, methods for pancreatic progenitor expansion and subsequent differentiation into insulin-producing beta cells would be extremely valuable. Here we establish three-dimensional culture conditions in Matrigel that enable the efficient expansion of dissociated mouse embryonic pancreatic progenitors. By manipulating the medium composition we generate either hollow spheres, which are mainly composed of pancreatic progenitors, or complex organoids that spontaneously undergo pancreatic morphogenesis and differentiation. The in vitro maintenance and expansion of pancreatic progenitors require active Notch and FGF signaling, thus recapitulating in vivo niche signaling interactions. Our experiments reveal new aspects of pancreas development, such as a community effect by which small groups of cells better maintain progenitor properties and expand more efficiently than isolated cells, as well as the requirement for three-dimensionality. Finally, growth conditions in chemically defined biomaterials pave the way for testing the biophysical and biochemical properties of the niche that sustains pancreatic progenitors.
Three-dimensional control of Tetrahymena pyriformis using artificial magnetotaxis
NASA Astrophysics Data System (ADS)
Hyung Kim, Dal; Seung Soo Kim, Paul; Agung Julius, Anak; Jun Kim, Min
2012-01-01
We demonstrate three-dimensional control with the eukaryotic cell Tetrahymena pyriformis (T. pyriformis) using two sets of Helmholtz coils for xy-plane motion and a single electromagnet for z-direction motion. T. pyriformis is modified to have artificial magnetotaxis with internalized magnetite. To track the cell's z-axis position, intensity profiles of non-motile cells at varying distances from the focal plane are used. During vertical motion along the z-axis, the intensity difference is used to determine the position of the cell. The three-dimensional control of the live microorganism T. pyriformis as a cellular robot shows great potential for practical applications in microscale tasks, such as target transport and cell therapy.
MULTISHOCKED,THREE-DIMENSIONAL SUPERSONIC FLOWFIELDS WITH REAL GAS EFFECTS
NASA Technical Reports Server (NTRS)
Kutler, P.
1994-01-01
This program determines the supersonic flowfield surrounding three-dimensional wing-body configurations of a delta wing. It was designed to provide the numerical computation of three dimensional inviscid, flowfields of either perfect or real gases about supersonic or hypersonic airplanes. The governing equations in conservation law form are solved by a finite difference method using a second order noncentered algorithm between the body and the outermost shock wave, which is treated as a sharp discontinuity. Secondary shocks which form between these boundaries are captured automatically. The flowfield between the body and outermost shock is treated in a shock capturing fashion and therefore allows for the correct formation of secondary internal shocks . The program operates in batch mode, is in CDC update format, has been implemented on the CDC 7600, and requires more than 140K (octal) word locations.
COMOC: Three dimensional boundary region variant, programmer's manual
NASA Technical Reports Server (NTRS)
Orzechowski, J. A.; Baker, A. J.
1974-01-01
The three-dimensional boundary region variant of the COMOC computer program system solves the partial differential equation system governing certain three-dimensional flows of a viscous, heat conducting, multiple-species, compressible fluid including combustion. The solution is established in physical variables, using a finite element algorithm for the boundary value portion of the problem description in combination with an explicit marching technique for the initial value character. The computational lattice may be arbitrarily nonregular, and boundary condition constraints are readily applied. The theoretical foundation of the algorithm, a detailed description on the construction and operation of the program, and instructions on utilization of the many features of the code are presented.
Miniaturized digital holography sensor for distal three-dimensional endoscopy.
Kolenovic, Ervin; Osten, Wolfgang; Klattenhoff, Reiner; Lai, Songcan; von Kopylow, Christoph; Jüptner, Werner
2003-09-01
A miniaturized sensor head for endoscopic measurements based on digital holography is described. The system was developed to measure the shape and the three-dimensional deformation of objects located at places to which there is no access by common measurement systems. A miniaturized optical sensor, including a complete digital holographic interferometer with a CCD camera, is placed at the end of a flexible endoscope. The diameter of the head is smaller than 10 mm. The system enables interferometric measurements to be made at speeds of as many as five reconstructions per second, and it can be used outside the laboratory under normal environmental conditions. Shape measurements are performed with two wavelengths for contouring, and the deformation is measured by digital holographic interferometry. To obtain full three-dimensional data in displacement measurements we illuminate the object sequentially from three different illumination directions. To increase the lateral resolution we use temporal phase shifting.
Recent developments in three-dimensional numerical estuarine models
Cheng, Ralph T.; Smith, Peter E.; Casulli, Vincenzo
1993-01-01
For a fixed cost, computing power increases 5 to 10 times every five years. The readily available computing resources have inspired new modal formulations and innovative model applications. Significant progress has been advanced in three-dimensional numerical estuarine modeling within the past three or four years. This paper attempts to review and summarize properties of new 3-D estuarine hydrodynamic models. The emphasis of the review is placed on the formulation, numerical methods. The emphasis of the review is placed on the formulation, numerical methods, spatial and temporal resolution, computational efficiency, and turbulence closure of new models. Recent research has provided guidelines for the proper use of 3-D models involving in the σ-transformation. Other models resort to a fixed level discretization in the vertical. The semi-implicit treatment in time-stepping models appears to have gained momentum. Future research in three-dimensional numerical modeling remains to be on computational efficiency and turbulent closure.
Three-dimensional surface reconstruction for industrial computed tomography
NASA Technical Reports Server (NTRS)
Vannier, M. W.; Knapp, R. H.; Gayou, D. E.; Sammon, N. P.; Butterfield, R. L.; Larson, J. W.
1985-01-01
Modern high resolution medical computed tomography (CT) scanners can produce geometrically accurate sectional images of many types of industrial objects. Computer software has been developed to convert serial CT scans into a three-dimensional surface form, suitable for display on the scanner itself. This software, originally developed for imaging the skull, has been adapted for application to industrial CT scanning, where serial CT scans thrrough an object of interest may be reconstructed to demonstrate spatial relationships in three dimensions that cannot be easily understood using the original slices. The methods of three-dimensional reconstruction and solid modeling are reviewed, and reconstruction in three dimensions from CT scans through familiar objects is demonstrated.
Three-dimensional optical holography using a plasmonic metasurface
Huang, Lingling; Chen, Xianzhong; Mühlenbernd, Holger; Zhang, Hao; Chen, Shumei; Bai, Benfeng; Tan, Qiaofeng; Jin, Guofan; Cheah, Kok-Wai; Qiu, Cheng-Wei; Li, Jensen; Zentgraf, Thomas; Zhang, Shuang
2013-01-01
Benefitting from the flexibility in engineering their optical response, metamaterials have been used to achieve control over the propagation of light to an unprecedented level, leading to highly unconventional and versatile optical functionalities compared with their natural counterparts. Recently, the emerging field of metasurfaces, which consist of a monolayer of photonic artificial atoms, has offered attractive functionalities for shaping wave fronts of light by introducing an abrupt interfacial phase discontinuity. Here we realize three-dimensional holography by using metasurfaces made of subwavelength metallic nanorods with spatially varying orientations. The phase discontinuity takes place when the helicity of incident circularly polarized light is reversed. As the phase can be continuously controlled in each subwavelength unit cell by the rod orientation, metasurfaces represent a new route towards high-resolution on-axis three-dimensional holograms with a wide field of view. In addition, the undesired effect of multiple diffraction orders usually accompanying holography is eliminated.
Three-dimensional radiation transfer modeling in a dicotyledon leaf
NASA Astrophysics Data System (ADS)
Govaerts, Yves M.; Jacquemoud, Stéphane; Verstraete, Michel M.; Ustin, Susan L.
1996-11-01
The propagation of light in a typical dicotyledon leaf is investigated with a new Monte Carlo ray-tracing model. The three-dimensional internal cellular structure of the various leaf tissues, including the epidermis, the palisade parenchyma, and the spongy mesophyll, is explicitly described. Cells of different tissues are assigned appropriate morphologies and contain realistic amounts of water and chlorophyll. Each cell constituent is characterized by an index of refraction and an absorption coefficient. The objective of this study is to investigate how the internal three-dimensional structure of the tissues and the optical properties of cell constituents control the reflectance and transmittance of the leaf. Model results compare favorably with laboratory observations. The influence of the roughness of the epidermis on the reflection and absorption of light is investigated, and simulation results confirm that convex cells in the epidermis focus light on the palisade parenchyma and increase the absorption of radiation.
High-resolution three-dimensional imaging radar
NASA Technical Reports Server (NTRS)
Cooper, Ken B. (Inventor); Chattopadhyay, Goutam (Inventor); Siegel, Peter H. (Inventor); Dengler, Robert J. (Inventor); Schlecht, Erich T. (Inventor); Mehdi, Imran (Inventor); Skalare, Anders J. (Inventor)
2010-01-01
A three-dimensional imaging radar operating at high frequency e.g., 670 GHz, is disclosed. The active target illumination inherent in radar solves the problem of low signal power and narrow-band detection by using submillimeter heterodyne mixer receivers. A submillimeter imaging radar may use low phase-noise synthesizers and a fast chirper to generate a frequency-modulated continuous-wave (FMCW) waveform. Three-dimensional images are generated through range information derived for each pixel scanned over a target. A peak finding algorithm may be used in processing for each pixel to differentiate material layers of the target. Improved focusing is achieved through a compensation signal sampled from a point source calibration target and applied to received signals from active targets prior to FFT-based range compression to extract and display high-resolution target images. Such an imaging radar has particular application in detecting concealed weapons or contraband.
Three-dimensional structure of Erwinia carotovora L-asparaginase
Kislitsyn, Yu. A. Kravchenko, O. V.; Nikonov, S. V. Kuranova, I. P.
2006-10-15
Three-dimensional structure of Erwinia carotovora L-asparaginase, which has antitumor activity and is used for the treatment of acute lymphoblastic leukemia, was solved at 3 A resolution and refined to R{sub cryst} = 20% and R{sub free} = 28%. Crystals of recombinant Erwinia carotovora L-asparaginase were grown by the hanging-drop vapor-diffusion method from protein solutions in a HEPES buffer (pH 6.5) and PEG MME 5000 solutions in a cacodylate buffer (pH 6.5) as the precipitant. Three-dimensional X-ray diffraction data were collected up to 3 A resolution from one crystal at room temperature. The structure was solved by the molecular replacement method using the coordinates of Erwinia chrysanthemi L-asparaginase as the starting model. The coordinates refined with the use of the CNS program package were deposited in the Protein Data Bank (PDB code 1ZCF)
Three-dimensional simulations of Nova capsule implosion experiments
Marinak, M.M.; Tipton, R.E.; Landen, O.L.
1995-11-01
Capsule implosion experiments carried out on the Nova laser are simulated with the three-dimensional HYDRA radiation hydrodynamics code. Simulations of ordered near single mode perturbations indicate that structures which evolve into round spikes can penetrate farthest into the hot spot. Bubble-shaped perturbations can burn through the capsule shell fastest, however, causing even more damage. Simulations of a capsule with multimode perturbations shows spike amplitudes evolving in good agreement with a saturation model during the deceleration phase. The presence of sizable low mode asymmetry, caused either by drive asymmetry or perturbations in the capsule shell, can dramatically affect the manner in which spikes approach the center of the hot spot. Three-dimensional coupling between the low mode shell perturbations intrinsic to Nova capsules and the drive asymmetry brings the simulated yields into closer agreement with the experimental values.
On anisotropic versions of three-dimensional pentamode metamaterials
NASA Astrophysics Data System (ADS)
Kadic, Muamer; Bückmann, Tiemo; Schittny, Robert; Wegener, Martin
2013-02-01
Pentamode materials are artificial solids with elastic properties that approximate those of isotropic liquids. The corresponding three-dimensional mechanical metamaterials or ‘meta-liquids’ have recently been fabricated. In contrast to normal liquids, anisotropic meta-liquids are also possible—a prerequisite for realizing many of the envisioned transformation-elastodynamics architectures. Here, we study several possibilities theoretically for introducing intentional anisotropy into three-dimensional pentamode metamaterials. In static continuum mechanics, the transition from anti-auxetic pentamode materials to auxetics is possible. Near this transition, in the dynamic case, approximately uniaxial versions of pentamode metamaterials deliver anisotropic longitudinal-wave phase velocities different by nearly a factor of 10 for realistically accessible microstructure parameters.
Three-dimensional tissue culture based on magnetic cell levitation.
Souza, Glauco R; Molina, Jennifer R; Raphael, Robert M; Ozawa, Michael G; Stark, Daniel J; Levin, Carly S; Bronk, Lawrence F; Ananta, Jeyarama S; Mandelin, Jami; Georgescu, Maria-Magdalena; Bankson, James A; Gelovani, Juri G; Killian, T C; Arap, Wadih; Pasqualini, Renata
2010-04-01
Cell culture is an essential tool in drug discovery, tissue engineering and stem cell research. Conventional tissue culture produces two-dimensional cell growth with gene expression, signalling and morphology that can be different from those found in vivo, and this compromises its clinical relevance. Here, we report a three-dimensional tissue culture based on magnetic levitation of cells in the presence of a hydrogel consisting of gold, magnetic iron oxide nanoparticles and filamentous bacteriophage. By spatially controlling the magnetic field, the geometry of the cell mass can be manipulated, and multicellular clustering of different cell types in co-culture can be achieved. Magnetically levitated human glioblastoma cells showed similar protein expression profiles to those observed in human tumour xenografts. Taken together, these results indicate that levitated three-dimensional culture with magnetized phage-based hydrogels more closely recapitulates in vivo protein expression and may be more feasible for long-term multicellular studies.
Three-Dimensional Modeling of Guide-Field Magnetic Reconnection
NASA Technical Reports Server (NTRS)
Hesse, Michael
2005-01-01
The dissipation mechanism of guide field magnetic reconnection remains a subject of intense scientific interest. On one hand, one set of recent studies have shown that particle inertia-based processes, which include thermal and bulk inertial effects, provide the reconnection electric field in the diffusion region. On the other hand, a second set of studies emphasizes the role of wave-particle interactions in providing anomalous resistivity in the diffusion region. In this presentation, we analyze three-dimensional PIC simulations of guide-field magnetic reconnection. Specific emphasis will be on the question whether thermal-inertia processes, mediated by the electron pressure tensor, remain a viable dissipation mechanism in fully three-dimensional systems.
Nonisentropic unsteady three dimensional small disturbance potential theory
NASA Technical Reports Server (NTRS)
Gibbons, M. D.; Whitlow, W., Jr.; Williams, M. H.
1986-01-01
Modifications that allow for more accurate modeling of flow fields when strong shocks are present were made into three dimensional transonic small disturbance (TSD) potential theory. The Engquist-Osher type-dependent differencing was incorporated into the solution algorithm. The modified theory was implemented in the XTRAN3S computer code. Steady flows over a rectangular wing with a constant NACA 0012 airfoil section and an aspect ratio of 12 were calculated for freestream Mach numbers (M) of 0.82, 0.84, and 0.86. The obtained results are compared using the modified and unmodified TSD theories and the results from a three dimensional Euler code are presented. Nonunique solutions in three dimensions are shown to appear for the rectangular wing as aspect ratio increases. Steady and unsteady results are shown for the RAE tailplane model at M = 0.90. Calculations using unmodified theory, modified theory and experimental data are compared.
Three-dimensional coherence of light speckles: Experiment
Magatti, D.; Gatti, A.; Ferri, F.
2009-05-15
We provide an experimental detailed study of the three-dimensional coherence properties of light speckles produced by different tunable pseudothermal sources. Our findings confirm the theoretical prediction of the companion article [A. Gatti et al., Phys. Rev. A 78, 063806 (2008)], according to which the longitudinal coherence of the speckles is ruled by ordinary diffraction laws only in the deep-Fresnel zone close to the source, deviates from this behavior in the Fresnel zone, and tends to become infinite when approaching the Fraunhofer zone. A quantitative comparison with theory is presented for Gaussian speckles in all the three regimes and for Airy speckles in the deep-Fresnel zone. Potential applications to three-dimensional imaging techniques are briefly discussed.
Three-dimensional simulation study of ionospheric plasma clouds
NASA Technical Reports Server (NTRS)
Zalesak, S. T.; Drake, J. F.; Huba, J. D.
1990-01-01
The results of fully three-dimensional numerical simulations of ionospheric plasma cloud evolution are presented. The evolution of the plasma cloud considered by Drake and Huba (1987) in the limit of vanishingly small ion compressibility is discussed. Simulations support the results of the analytical theory: finite plasma temperature, combined with fully three-dimensional plasma dynamics, is a stabilizing influence on plasma cloud evolution. This stability is associated with sheared azimuthal ion flows in the vicinity of the cloud surface. Cloud evolution using realistic values of ion compressibility show that the cloud rapidly diffuses to a state in which the sheared azimuthal flow is substantially reduced; subsequently, the cloud becomes unstable and structures.
Three-dimensional potential energy surface of Ar–CO
Sumiyoshi, Yoshihiro; Endo, Yasuki
2015-01-14
A three-dimensional intermolecular potential energy surface of the Ar–CO complex has been determined by fitting most of the previously reported spectroscopic data, where observed transition frequencies by microwave, millimeter-wave, submillimeter-wave, and infrared spectroscopy were reproduced simultaneously within their experimental accuracies. A free rotor model Hamiltonian considering all the freedom of motions for an atom-diatom system was applied to calculate vibration-rotation energies. A three-dimensional potential energy surface obtained by ab initio calculations at the CCSD(T)-F12b/aug-cc-pV5Z level of theory was parameterized by a model function consisting of 46 parameters. They were used as initial values for the least-squares analysis of the experimental data. A total of 20 parameters were optimized to reproduce all the spectroscopic data.
Three-dimensional reconstruction of coronal mass ejections
NASA Technical Reports Server (NTRS)
Jackson, Bernard V.; Hick, Paul
1994-01-01
Computer assisted tomography (CAT) techniques are used to reconstruct the three dimensional shape of coronal mass ejections in the interplanetary medium. Both the Helios 2 spacecraft zodiacal-light photometers and the Solwind coronograph measure changes in Thomson scattering of sunlight from electrons. The technique from near-perpendicular Solwind and Helios views are applied to determine the density of a mass ejection which left the solar surface on 24 May 1979. The coronograph and the Helios perspective views are not simultaneous; the Solwind observations extend outward to sky plane distances of only 10 of the solar radius, whereas the Helios 16 photometer observes to as close as 17 of the solar radius from the sun. The solution is obtained by assuming outward radial expansion and that the coronal mass ejections (CME's) have the same speed everywhere at the same height. The analyses show that CME's are extensive three dimensional structures (the CME of 24 May appears approximately shell) like in three dimensions.
Three-dimensional potential energy surface of Ar-CO.
Sumiyoshi, Yoshihiro; Endo, Yasuki
2015-01-14
A three-dimensional intermolecular potential energy surface of the Ar-CO complex has been determined by fitting most of the previously reported spectroscopic data, where observed transition frequencies by microwave, millimeter-wave, submillimeter-wave, and infrared spectroscopy were reproduced simultaneously within their experimental accuracies. A free rotor model Hamiltonian considering all the freedom of motions for an atom-diatom system was applied to calculate vibration-rotation energies. A three-dimensional potential energy surface obtained by ab initio calculations at the CCSD(T)-F12b/aug-cc-pV5Z level of theory was parameterized by a model function consisting of 46 parameters. They were used as initial values for the least-squares analysis of the experimental data. A total of 20 parameters were optimized to reproduce all the spectroscopic data.
Three-Dimensional Flow in Compressors and Channels.
1985-11-01
case where shock waves occur, were begun. Considerable effort was expanded upon the problem by both principal investigators, Dr. R. * L. Enlow , visiting...done by Dr. Enlow ()was presented at the Second Australian * Mathematics Convention. 9 Because the flow relative to the blades has a gradient, the angle...34Transonic Shear Flow in a Three-Dimensional Channel," Technical Report N00014-79-C-0285-T, January 1981. 6. Enlow , R.L., "Wavefront Propagation in Non
Three-dimensional Analysis of Nanomaterials by Scanning Probe Nanotomography
NASA Astrophysics Data System (ADS)
Efimov, Anton E.; Agapova, Olga I.; Mochalov, Konstantin E.; Agapov, Igor I.
Micro and nanostructure of scaffolds made from fibroin of Bombyx mori silkworm by salt leaching technique was studied by scanning probe nanotomography. Nanopores with dimensions in range from 30 to 180 nm are observed in the scaffold volume. Three - dimensional analysis of obtained data shows that degree of scaffold nanoporosity is 0.5% and nanopores are not interconnected with each other. Usage of scanning probe nanotomography technique enables to obtain unique nanoscale information of 3D structure of biopolymer nanomaterials.
Rapid measurement of three-dimensional diffusion tensor
NASA Astrophysics Data System (ADS)
Cho, H.; Ren, X.-H.; Sigmund, E. E.; Song, Y.-Q.
2007-04-01
In this article, the authors demonstrate a rapid NMR method to measure a full three-dimensional diffusion tensor. This method is based on a multiple modulation multiple echo sequence and utilizes static and pulsed magnetic field gradients to measure diffusion along multiple directions simultaneously. The pulse sequence was optimized using a well-known linear inversion metric (condition number) and successfully tested on both isotropic (water) and anisotropic (asparagus) diffusion systems.
Three-dimensional inelastic analysis methods for hot section components
NASA Technical Reports Server (NTRS)
Todd, E. S.
1987-01-01
The objective of this program is to produce a series of new computer codes that permit more accurate and efficient three-dimensional inelastic structural analysis of combustor liners, turbine blades, and turbine vanes. Each code embodies a progression of mathematical models for increasingly comprehensive representation of the geometrical features, loading conditions, and forms of nonlinear material response that distinguish these three groups of hot section components.
Multi-cellular, three-dimensional living mammalian tissue
NASA Technical Reports Server (NTRS)
Goodwin, Thomas J. (Inventor); Wolf, David A. (Inventor)
1994-01-01
The present invention relates to a multicellular, three-dimensional, living mammalian tissue. The tissue is produced by a co-culture process wherein two distinct types of mammalian cells are co-cultured in a rotating bioreactor which is completely filled with culture media and cell attachment substrates. As the size of the tissue assemblies formed on the attachment substrates changes, the rotation of the bioreactor is adjusted accordingly.
Simulating Photons and Plasmons in a Three-dimensional Lattice
Pletzer, A.; Shvets, G.
2002-09-03
Three-dimensional metallic photonic structures are studied using a newly developed mixed finite element-finite difference (FE-FD) code, Curly3d. The code solves the vector Helmholtz equation as an eigenvalue problem in the unit cell of a triply periodic lattice composed of conductors and/or dielectrics. The mixed FE-FD discretization scheme ensures rapid numerical convergence of the eigenvalue and allows the code to run at low resolution. Plasmon and photonic band structure calculations are presented.
Code System for Three-Dimensional Hydraulic Reactor Core Analysis.
ROBERT,; BENEDETTI, L.
2001-03-05
Version 00 SCORE-EVET was developed to study multidimensional transient fluid flow in nuclear reactor fuel rod arrays. The conservation equations used were derived by volume averaging the transient compressible three-dimensional local continuum equations in Cartesian coordinates. No assumptions associated with subchannel flow have been incorporated into the derivation of the conservation equations. In addition to the three-dimensional fluid flow equations, the SCORE-EVET code contains a one-dimensional steady state solution scheme to initialize the flow field, steady state and transient fuel rod conduction models, and comprehensive correlation packages to describe fluid-to-fuel rod interfacial energy and momentum exchange. Velocity and pressure boundary conditions can be specified as a function of time and space to model reactor transient conditions, such as a hypothesized loss-of-coolant accident (LOCA) or flow blockage. The basic volume-averaged transient three-dimensional equations for flow in porous media are solved in their general form with constitutive relationships and boundary conditions tailored to define the porous medium as a matrix of fuel rods. By retaining generality in the form of the conservation equations, a wide range of fluid flow problem configurations, from computational regions representing a single fuel rod subchannel to multichannels, or even regions without a fuel rod, can be modeled without restrictive assumptions. The completeness of the conservation equations has allowed SCORE-EVET to be used, with modification to the constitutive relationships, to calculate three-dimensional laminar boundary layer development, flow fields in large bodies of water, and, with the addition of a turbulence model, turbulent flow in pipe expansions and tees.
Three-dimensional stiffness of the carpal arch.
Gabra, Joseph N; Li, Zong-Ming
2016-01-04
The carpal arch of the wrist is formed by irregularly shaped carpal bones interconnected by numerous ligaments, resulting in complex structural mechanics. The purpose of this study was to determine the three-dimensional stiffness characteristics of the carpal arch using displacement perturbations. It was hypothesized that the carpal arch would exhibit an anisotropic stiffness behavior with principal directions that are oblique to the conventional anatomical axes. Eight (n=8) cadavers were used in this study. For each specimen, the hamate was fixed to a custom stationary apparatus. An instrumented robot arm applied three-dimensional displacement perturbations to the ridge of trapezium and corresponding reaction forces were collected. The displacement-force data were used to determine a three-dimensional stiffness matrix using least squares fitting. Eigendecomposition of the stiffness matrix was used to identify the magnitudes and directions of the principal stiffness components. The carpal arch structure exhibited anisotropic stiffness behaviors with a maximum principal stiffness of 16.4±4.6N/mm that was significantly larger than the other principal components of 3.1±0.9 and 2.6±0.5N/mm (p<0.001). The principal direction of the maximum stiffness was pronated within the cross section of the carpal tunnel which is accounted for by the stiff transverse ligaments that tightly bind distal carpal arch. The minimal principal stiffness is attributed to the less constraining articulation between the trapezium and scaphoid. This study provides advanced characterization of the wrist׳s three-dimensional structural stiffness for improved insight into wrist biomechanics, stability, and function.
Three-dimensional compressible and stretchable conductive composites.
Yu, You; Zeng, Jifang; Chen, Chaojian; Xie, Zhuang; Guo, Ruisheng; Liu, Zhilu; Zhou, Xuechang; Yang, Yong; Zheng, Zijian
2014-02-01
Three-dimensional (3D) conductive composites with remarkable flexibility, compressibility, and stretchability are fabricated by solution deposition of thin metal coatings on chemically modified, macroscopically continuous, 3D polyurethane sponges, followed by infiltration of the metallic sponges with polydimethylsiloxane (PDMS). These low-cost conductive composites are used as high-performance interconnects for flexible and stretchable light-emitting diode (LED) arrays, even with severe surface abrasion or cutting.
Time-Domain Simulation of Three Dimensional Quantum Wires
Mossman, Sean; Kuzyk, Mark G.
2016-01-01
A method is presented to calculate the eigenenergies and eigenfunctions of quantum wires. This is a true three-dimensional method based on a direct implementation of the time-dependent Schrödinger equation. It makes no approximations to the Schrödinger equation other than the finite-difference approximation of the space and time derivatives. The accuracy of our method is tested by comparing it to analytical results in a cylindrical wire. PMID:27124603
Three-dimensional surface reconstruction from multistatic SAR images.
Rigling, Brian D; Moses, Randolph L
2005-08-01
This paper discusses reconstruction of three-dimensional surfaces from multiple bistatic synthetic aperture radar (SAR) images. Techniques for surface reconstruction from multiple monostatic SAR images already exist, including interferometric processing and stereo SAR. We generalize these methods to obtain algorithms for bistatic interferometric SAR and bistatic stereo SAR. We also propose a framework for predicting the performance of our multistatic stereo SAR algorithm, and, from this framework, we suggest a metric for use in planning strategic deployment of multistatic assets.
A Three Dimensional Non-Singular Modelling of Rigid Manipulators.
1987-12-01
511111 OTC FILE COPY (1) ’ NAVAL POSTGRADUATE SCHOOL 0 ’ Monterey, California IDTIC I{ IELECTE S MAR 08 8 f 0? THESIS A THREE DIMENSIONAL NON-SINGULAR...MODELLING OF RIGID MANIPULATORS by Sadrettin Altinok December 1987 Thesis Advisor D.L. Smith Approved for public release; distribution is unlimited. 88...MASTERS THESIS FROM _ TO 1987 DECEMBER iC 6 16 SUPPLEMENTARY NOTATION 17 COSA T i CODES 18 SUBJECT TERMS (Continue on reverse f necessary and identify by
Three-dimensional terahertz computed tomography of human bones.
Bessou, Maryelle; Chassagne, Bruno; Caumes, Jean-Pascal; Pradère, Christophe; Maire, Philippe; Tondusson, Marc; Abraham, Emmanuel
2012-10-01
Three-dimensional terahertz computed tomography has been used to investigate dried human bones such as a lumbar vertebra, a coxal bone, and a skull, with a direct comparison with standard radiography. In spite of lower spatial resolution compared with x-ray, terahertz imaging clearly discerns a compact bone from a spongy one, with strong terahertz absorption as shown by additional terahertz time-domain transmission spectroscopy.
Separation behavior of boundary layers on three-dimensional wings
NASA Technical Reports Server (NTRS)
Stock, H. W.
1981-01-01
An inverse boundary layer procedure for calculating separated, turbulent boundary layers at infinitely long, crabbing wing was developed. The procedure was developed for calculating three dimensional, incompressible turbulent boundary layers was expanded to adiabatic, compressible flows. Example calculations with transsonic wings were made including viscose effects. In this case an approximated calculation method described for areas of separated, turbulent boundary layers, permitting calculation of this displacement thickness. The laminar boundary layer development was calculated with inclined ellipsoids.
Three dimensional tracking with misalignment between display and control axes
NASA Technical Reports Server (NTRS)
Ellis, Stephen R.; Tyler, Mitchell; Kim, Won S.; Stark, Lawrence
1992-01-01
Human operators confronted with misaligned display and control frames of reference performed three dimensional, pursuit tracking in virtual environment and virtual space simulations. Analysis of the components of the tracking errors in the perspective displays presenting virtual space showed that components of the error due to visual motor misalignment may be linearly separated from those associated with the mismatch between display and control coordinate systems. Tracking performance improved with several hours practice despite previous reports that such improvement did not take place.
Anomalous three-dimensional symmetries of solar-wind plasma.
Bershadskii, A
2002-10-01
An example of a combination of Kolmogorov three-dimensional properties with Alfvén two-dimensional properties in solar-wind plasma is given using recent data obtained with the Advanced Composition Explorer satellite at the L1 libration point. Both spectral and moments scaling analyses are used to demonstrate the possibility of such a combination. Two-decade scaling and the large number of the scaling exponents under consideration indicate the robustness of this observation.
Development of three-dimensional memory (3D-M)
NASA Astrophysics Data System (ADS)
Yu, Hong-Yu; Shen, Chen; Jiang, Lingli; Dong, Bin; Zhang, Guobiao
2016-10-01
Since the invention of 3-D ROM in 1996, three-dimensional memory (3D-M) has been under development for nearly two decades. In this presentation, we'll review the 3D-M history and compare different 3D-Ms (including 3D-OTP from Matrix Semiconductor, 3D-NAND from Samsung and 3D-XPoint from Intel/Micron).
Coherent states on horospheric three-dimensional Lobachevsky space
NASA Astrophysics Data System (ADS)
Kurochkin, Yu.; Rybak, I.; Shoukavy, Dz.
2016-08-01
In the paper it is shown that due to separation of variables in the Laplace-Beltrami operator (Hamiltonian of a free quantum particle) in horospheric and quasi-Cartesian coordinates of three dimensional Lobachevsky space, it is possible to introduce standard ("conventional" according to Perelomov [Generalized Coherent States and Their Applications (Springer-Verlag, 1986), p. 320]) coherent states. Some problems (oscillator on horosphere, charged particle in analogy of constant uniform magnetic field) where coherent states are suitable for treating were considered.
Three dimensional flow computations in a turbine scroll
NASA Technical Reports Server (NTRS)
Hamed, A.; Ghantous, C. A.
1982-01-01
The compressible three dimensional inviscid flow in the scroll and vaneless nozzle of radial inflow turbines is analyzed. A FORTRAN computer program for the numerical solution of this complex flow field using the finite element method is presented. The program input consists of the mass flow rate and stagnation conditions at the scroll inlet and of the finite element discretization parameters and nodal coordinates. The output includes the pressure, Mach number and velocity magnitude and direction at all the nodal points.
Characteristic boundary conditions for three-dimensional transonic unsteady aerodynamics
NASA Technical Reports Server (NTRS)
Whitlow, W., Jr.
1984-01-01
Characteristic far-field boundary conditions for the three-dimensional unsteady transonic small disturbance potential equation have been developed. The boundary conditions were implemented in the XTRAN3S finite difference code and tested for a flat plate rectangular wing with a pulse in angle of attack; the freestream Mach number was 0.85. The calculated force response shows that the characteristic boundary conditions reduce disturbances that are reflected from the computational boundaries.
Purification Techniques for Three-Dimensional DNA Nanostructures.
Meyer, Travis A
2017-01-01
Separation of self-assembled three-dimensional nanostructures from excess staple strands, misfolded structures, or unattached functional elements is critical for downstream applications. Numerous purification techniques exist, with varying yields, purities, and hetero-element compatibilities. In this chapter, we focus on three such techniques-agarose gel electrophoresis, ultrafiltration, and polymeric bead pull-down-which together satisfy requirements for a range of applications.
Fully Three-Dimensional Virtual-Reality System
NASA Technical Reports Server (NTRS)
Beckman, Brian C.
1994-01-01
Proposed virtual-reality system presents visual displays to simulate free flight in three-dimensional space. System, virtual space pod, is testbed for control and navigation schemes. Unlike most virtual-reality systems, virtual space pod would not depend for orientation on ground plane, which hinders free flight in three dimensions. Space pod provides comfortable seating, convenient controls, and dynamic virtual-space images for virtual traveler. Controls include buttons plus joysticks with six degrees of freedom.
Three-dimensional chiral skyrmions with attractive interparticle interactions
NASA Astrophysics Data System (ADS)
Leonov, A. O.; Monchesky, T. L.; Loudon, J. C.; Bogdanov, A. N.
2016-09-01
We introduce a new class of isolated three-dimensional skyrmion that can occur within the cone phase of chiral magnetic materials. These novel solitonic states consist of an axisymmetric core separated from the host phase by an asymmetric shell. These skyrmions attract one another. We derive regular solutions for isolated skyrmions arising in the cone phase of cubic helimagnets and investigate their bound states.
Four-Dimensional Entropy from Three-Dimensional Gravity.
Carlip, S
2015-08-14
At the horizon of a black hole, the action of (3+1)-dimensional loop quantum gravity acquires a boundary term that is formally identical to an action for three-dimensional gravity. I show how to use this correspondence to obtain the entropy of the (3+1)-dimensional black hole from well-understood conformal field theory computations of the entropy in (2+1)-dimensional de Sitter space.
Reentrance and ultrametricity in three-dimensional Ising spin glasses
NASA Astrophysics Data System (ADS)
Katzgraber, Helmut G.; Thomas, Creighton K.; Hartmann, Alexander K.
2012-02-01
We study the three-dimensional Edwards-Anderson Ising spin glass with bimodal disorder with a fraction of 22.8% antiferromagnetic bonds. Parallel tempering Monte Carlo simulations down to very low temperatures show that for this fraction of antiferromagnetic bonds the phase diagram of the system is reentrant, in agreement with previous results. Furthemore, using a clustering analysis, we analyze the ultrametric properties of phase space for this model.