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1

Facial biometrics based on 2D vector geometry

NASA Astrophysics Data System (ADS)

The main challenge of facial biometrics is its robustness and ability to adapt to changes in position orientation, facial expression, and illumination effects. This research addresses the predominant deficiencies in this regard and systematically investigates a facial authentication system in the Euclidean domain. In the proposed method, Euclidean geometry in 2D vector space is being constructed for features extraction and the authentication method. In particular, each assigned point of the candidates' biometric features is considered to be a 2D geometrical coordinate in the Euclidean vector space. Algebraic shapes of the extracted candidate features are also computed and compared. The proposed authentication method is being tested on images from the public "Put Face Database". The performance of the proposed method is evaluated based on Correct Recognition (CRR), False Acceptance (FAR), and False Rejection (FRR) rates. The theoretical foundation of the proposed method along with the experimental results are also presented in this paper. The experimental results demonstrate the effectiveness of the proposed method.

Malek, Obaidul; Venetsanopoulos, Anastasios; Androutsos, Dimitrios

2014-05-01

2

dofs. Pascal's rectangle, Pascal's triangle and Pascal's pyramid provide a systematic selection process for accomplishing this selection process for 2-D quadrilateral, 2-D triangular and 3-D hexahedral geometries respectively. Numerical studies...

Maduri, Rajesh Kumar

2008-02-01

3

Decaying 2D Turbulence in Bounded Domains: Influence of the Geometry

Decaying 2D Turbulence in Bounded Domains: Influence of the Geometry Kai Schneider1 and Marie Farge to a semiÂimplicit time discretization with adaptive time stepping. We study the influence of the geometry different geometries, a circle, a square, a triangle and a torus and we show that the geometry plays

Ã?cole Normale SupÃ©rieure

4

Boundary treatments for 2D elliptic mesh generation in complex geometries

Technology Transfer Automated Retrieval System (TEKTRAN)

This paper presents a boundary treatment method for 2D elliptic mesh generation in complex geometries. Corresponding to Neumann- Dirichlet boundary conditions (sliding boundary conditions), the proposed method aims at achieving orthogonal and smooth nodal distribution along irregular boundaries. In ...

5

GEOMETRY-CONSTRAINED CORONARY ARTERIES MOTION ESTIMATION FROM 2D ANGIOGRAMS - APPLICATION of coronary arteries. It exploits the geometry of acquisition to strongly constrain the problem, thereby of an angiographic exam into right or left artery tree. Index Terms-- Coronary arteries, motion estimation. 1

Paris-Sud XI, UniversitÃ© de

6

Multiview Geometry for Texture Mapping 2D Images Onto 3D Range Data

The photorealistic modeling of large-scale scenes, such as urban structures, requires a fusion of range sensing tech- nology and traditional digital photography. This paper presents a system that integrates multiview geometry and automated 3D registration techniques for texture mapping 2D images onto 3D range data. The 3D rangescans and the 2D photographs are respectively used to generate a pair of

Lingyun Liu; Gene Yu; George Wolberg; Siavash Zokai

2006-01-01

7

Radiation transport calculation in high enthalpy environments for 2D-axisymmetric geometries

NASA Astrophysics Data System (ADS)

The radiative source terms and boundary heat fluxes for generic, 2D-axisymmetric geometries are presently obtained via a Monte Carlo method whose geometrical discretization employs curvilinear structured grids. Attention is given to both the spectral behavior of gas radiation and the thermochemical nonequilibrium conditions of the medium, using the NEQAIR data base. The radiation-simulation method proceeds from a given flowfield solution for the given geometry; the radiative source terms are obtained in a form that is adequate for coupling with the flowfield energy equations.

Gogel, T. H.; Dupuis, M.; Messerschmid, E. W.

1993-07-01

8

Purpose: Pencil beam algorithms are commonly used for proton therapy dose calculations. Szymanowski and Oelfke ['Two-dimensional pencil beam scaling: An improved proton dose algorithm for heterogeneous media,' Phys. Med. Biol. 47, 3313-3330 (2002)] developed a two-dimensional (2D) scaling algorithm which accurately models the radial pencil beam width as a function of depth in heterogeneous slab geometries using a scaled expression for the radial kernel width in water as a function of depth and kinetic energy. However, an assumption made in the derivation of the technique limits its range of validity to cases where the input expression for the radial kernel width in water is derived from a local scattering power model. The goal of this work is to derive a generalized form of 2D pencil beam scaling that is independent of the scattering power model and appropriate for use with any expression for the radial kernel width in water as a function of depth. Methods: Using Fermi-Eyges transport theory, the authors derive an expression for the radial pencil beam width in heterogeneous slab geometries which is independent of the proton scattering power and related quantities. The authors then perform test calculations in homogeneous and heterogeneous slab phantoms using both the original 2D scaling model and the new model with expressions for the radial kernel width in water computed from both local and nonlocal scattering power models, as well as a nonlocal parameterization of Moliere scattering theory. In addition to kernel width calculations, dose calculations are also performed for a narrow Gaussian proton beam. Results: Pencil beam width calculations indicate that both 2D scaling formalisms perform well when the radial kernel width in water is derived from a local scattering power model. Computing the radial kernel width from a nonlocal scattering model results in the local 2D scaling formula under-predicting the pencil beam width by as much as 1.4 mm (21%) at the depth of the Bragg peak for a 220 MeV proton beam in homogeneous water. This translates into a 32% dose discrepancy for a 5 mm Gaussian proton beam. Similar trends were observed for calculations made in heterogeneous slab phantoms where it was also noted that errors tend to increase with greater beam penetration. The generalized 2D scaling model performs well in all situations, with a maximum dose error of 0.3% at the Bragg peak in a heterogeneous phantom containing 3 cm of hard bone. Conclusions: The authors have derived a generalized form of 2D pencil beam scaling which is independent of the proton scattering power model and robust to the functional form of the radial kernel width in water used for the calculations. Sample calculations made with this model show excellent agreement with expected values in both homogeneous water and heterogeneous phantoms.

Westerly, David C. [Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado 80045 (United States); Mo Xiaohu; DeLuca, Paul M. Jr. [Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53705 (United States); Tome, Wolfgang A. [Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53705 and Institute of Onco-Physics, Albert Einstein College of Medicine and Division of Medical Physics, Department of Radiation Oncology, Montefiore Medical Center, Bronx, New York 10461 (United States); Mackie, Thomas R. [Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53705 and Department of Human Oncology, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53792 (United States)

2013-06-15

9

GEOMETRY AND SPECTRUM IN 2D MAGNETIC WELLS NICOLAS RAYMOND AND SAN V~U NGO. C

GEOMETRY AND SPECTRUM IN 2D MAGNETIC WELLS NICOLAS RAYMOND AND SAN V~U NGO. C Abstract. This paper: June 27, 2013. 1 hal-00836344,version2-27Jun2013 #12;2 NICOLAS RAYMOND AND SAN V~U NGO. C expansions

Paris-Sud XI, UniversitÃ© de

10

Large-eddy simulation with complex 2-D geometries using a parallel finite-element/spectral algorithm

NASA Astrophysics Data System (ADS)

A parallel stabilized finite-element/spectral formulation is presented for incompressible large-eddy simulation with complex 2-D geometries. A unique discretization scheme is developed consisting of a streamline-upwind Petrov-Galerkin/Pressure-Stabilized Petrov-Galerkin (SUPG/PSPG) finite-element discretization in the 2-D plane with a collocated spectral/pseudospectral discretization in the out-of-plane direction. This formulation provides an efficient approach for solving 3-D flows over arbitrary 2-D geometries. Utilizing this discretization and through explicit temporal treatment of the non-linear terms, the system of equations for each Fourier mode is decoupled within each time step. A novel parallelization approach is then taken, where the computational work is partitioned in Fourier space. A validation of the algorithm is presented via comparison of results for flow past a circular cylinder with published values for Re=195, 300, and 3900.

Snyder, D. O.; Degrez, G.

2003-04-01

11

The differences in the development of Rayleigh-Taylor instability in 2D and 3D geometries

NASA Astrophysics Data System (ADS)

Results are presented from theoretical analysis and numerical simulations aimed to clarify specific features of Rayleigh-Taylor instability in 2D and 3D geometries. Two series of simulations, one with an isolated single-mode perturbation of the interface and the other with a random density perturbation, were performed. It is shown that the relative evolutions of integral characteristics for the first and the second series are different in 2D and 3D geometries. An attempt is made to interpret this result in the framework of the previously developed evolutionary approach based on the concept of the "critical age" of the perturbation (where, by the age is meant the product of the wavenumber and amplitude). The critical age corresponds to the destruction of the main mushroom-like structure formed during the development of Rayleigh-Taylor instability due to the onset of the secondary Kelvin-Helmholtz instability.

Kuchugov, P. A.; Rozanov, V. B.; Zmitrenko, N. V.

2014-06-01

12

Evaluation of 2D shallow-water model for spillway flow with a complex geometry

Technology Transfer Automated Retrieval System (TEKTRAN)

Although the two-dimensional (2D) shallow water model is formulated based on several assumptions such as hydrostatic pressure distribution and vertical velocity is negligible, as a simple alternative to the complex 3D model, it has been used to compute water flows in which these assumptions may be ...

13

2D AND 3D INVERSE BOUNDARY AND INVERSE GEOMETRY BEM SOLUTION IN CONTINUOUS CASTING

This paper discusses an inverse solution consisting of the boundary condition estimation and the phase change front identification in continuous casting process. The solution procedure utilizes sensitivity coecients and temperature measurements inside the solid phase. The algorithms proposed make use of the Boundary Element Method (BEM) in both 2D and 3D case. With the purpose of limiting a number of

A. J. NOWAK; I. NOWAK

14

Determining Transition State Geometries in Liquids Using 2D-IR

Many properties of chemical reactions are determined by the transition state connecting reactant and product, yet it is difficult to directly obtain any information about these short-lived structures in liquids. We show that two-dimensional infrared (2D-IR) spectroscopy can provide direct information about transition states by tracking the transformation of vibrational modes as a molecule crossed a transition state. We successfully monitored a simple chemical reaction, the fluxional rearrangement of Fe(CO)5, in which the exchange of axial and equatorial CO ligands causes an exchange of vibrational energy between the normal modes of the molecule. This energy transfer provides direct evidence regarding the time scale, transition state, and mechanism of the reaction.

Harris, Charles; Cahoon, James F.; Sawyer, Karma R.; Schlegel, Jacob P.; Harris, Charles B.

2007-12-11

15

Geometry induced potential on a 2D-section of a wormhole: catenoid

We show that a two dimensional wormhole geometry is equivalent to a catenoid, a minimal surface. We then obtain the curvature induced geometric potential and show that the ground state with zero energy corresponds to a reflectionless potential. By introducing an appropriate coordinate system we also obtain bound states for different angular momentum channels. Our findings can be realized in suitably bent bilayer graphene sheets with a neck or in a honeycomb lattice with an array of dislocations or in nanoscale waveguides in the shape of a catenoid.

Rossen Dandoloff; Avadh Saxena; Bjorn Jensen

2009-12-11

16

Single-atom trapping in holographic 2D arrays of microtraps with arbitrary geometries

We demonstrate single-atom trapping in two-dimensional arrays of microtraps with arbitrary geometries. We generate the arrays using a Spatial Light Modulator (SLM), with which we imprint an appropriate phase pattern on an optical dipole trap beam prior to focusing. We trap single $^{87}{\\rm Rb}$ atoms in the sites of arrays containing up to $\\sim100$ microtraps separated by distances as small as $3\\;\\mu$m, with complex structures such as triangular, honeycomb or kagome lattices. Using a closed-loop optimization of the uniformity of the trap depths ensures that all trapping sites are equivalent. This versatile system opens appealing applications in quantum information processing and quantum simulation, e.g. for simulating frustrated quantum magnetism using Rydberg atoms.

Nogrette, Florence; Ravets, Sylvain; Barredo, Daniel; Béguin, Lucas; Vernier, Aline; Lahaye, Thierry; Browaeys, Antoine

2014-01-01

17

Single-atom trapping in holographic 2D arrays of microtraps with arbitrary geometries

We demonstrate single-atom trapping in two-dimensional arrays of microtraps with arbitrary geometries. We generate the arrays using a Spatial Light Modulator (SLM), with which we imprint an appropriate phase pattern on an optical dipole trap beam prior to focusing. We trap single $^{87}{\\rm Rb}$ atoms in the sites of arrays containing up to $\\sim100$ microtraps separated by distances as small as $3\\;\\mu$m, with complex structures such as triangular, honeycomb or kagome lattices. Using a closed-loop optimization of the uniformity of the trap depths ensures that all trapping sites are equivalent. This versatile system opens appealing applications in quantum information processing and quantum simulation, e.g. for simulating frustrated quantum magnetism using Rydberg atoms.

Florence Nogrette; Henning Labuhn; Sylvain Ravets; Daniel Barredo; Lucas Béguin; Aline Vernier; Thierry Lahaye; Antoine Browaeys

2014-02-21

18

A numerical study on the thermal initiation of a confined explosive in 2-D geometry.

Insensitive munitions design against thermal stimuli like slow or fast cook-off has become a significant requirement for today's munitions. In order to achieve insensitive munitions characteristics, the response of the energetic material needs to be predicted against heating stimuli. In this study, a 2D numerical code was developed to simulate the slow and fast cook-off heating conditions of confined munitions and to obtain the response of the energetic materials. Computations were performed in order to predict the transient temperature distribution, the ignition time, and the location of ignition in the munitions. These predictions enable the designers to have an idea of when and at which location the energetic material ignites under certain adverse surrounding conditions. In the paper, the development of the code is explained and the numerical results are compared with available experimental and numerical data in the literature. Additionally, a parametric study was performed showing the effect of dimensional scaling of munitions and the heating rate on the ignition characteristics. PMID:21130568

Aydemir, Erdo?an; Ulas, Abdullah

2011-02-15

19

NASA Astrophysics Data System (ADS)

With a dedicated breast CT system using a quasi-monochromatic x-ray source and flat-panel digital detector, the 2D and 3D scatter to primary ratios (SPR) of various geometric phantoms having different densities were characterized in detail. Projections were acquired using geometric and anthropomorphic breast phantoms. Each phantom was filled with 700ml of 5 different water-methanol concentrations to simulate effective boundary densities of breast compositions from 100% glandular (1.0g/cm3) to 100% fat (0.79g/cm3). Projections were acquired with and without a beam stop array. For each projection, 2D scatter was determined by cubic spline interpolating the values behind the shadow of each beam stop through the object. Scatter-corrected projections were obtained by subtracting the scatter, and the 2D SPRs were obtained as a ratio of the scatter to scatter-corrected projections. Additionally the (un)corrected data were individually iteratively reconstructed. The (un)corrected 3D volumes were subsequently subtracted, and the 3D SPRs obtained from the ratio of the scatter volume-to-scatter-corrected (or primary) volume. Results show that the 2D SPR values peak in the center of the volumes, and were overall highest for the simulated 100% glandular composition. Consequently, scatter corrected reconstructions have visibly reduced cupping regardless of the phantom geometry, as well as more accurate linear attenuation coefficients. The corresponding 3D SPRs have increased central density, which reduces radially. Not surprisingly, for both 2D and 3D SPRs there was a dependency on both phantom geometry and object density on the measured SPR values, with geometry dominating for 3D SPRs. Overall, these results indicate the need for scatter correction given different geometries and breast densities that will be encountered with 3D cone beam breast CT.

Shah, Jainil; Pachon, Jan H.; Madhav, Priti; Tornai, Martin P.

2011-03-01

20

We present a new spatial discretization of the discrete-ordinates transport equation in two-dimensional cylindrical (RZ) geometry for arbitrary polygonal meshes. This discretization is a discontinuous finite element method that utilizes the piecewise linear basis functions developed by Stone and Adams. We describe an asymptotic analysis that shows this method to be accurate for many problems in the thick diffusion limit

T S Bailey; M L Adams; J H Chang

2008-01-01

21

NASA Astrophysics Data System (ADS)

Stochastic modelling is a useful way of simulating complex hard-rock aquifers as hydrological properties (permeability, porosity etc.) can be described using random variables with known statistics. However, very few studies have assessed the influence of topological uncertainty (i.e. the variability of thickness of conductive zones in the aquifer), probably because it is not easy to retrieve accurate statistics of the aquifer geometry, especially in hard rock context. In this paper, we assessed the potential of using geophysical surveys to describe the geometry of a hard rock-aquifer in a stochastic modelling framework. The study site was a small experimental watershed in South India, where the aquifer consisted of a clayey to loamy-sandy zone (regolith) underlain by a conductive fissured rock layer (protolith) and the unweathered gneiss (bedrock) at the bottom. The spatial variability of the thickness of the regolith and fissured layers was estimated by electrical resistivity tomography (ERT) profiles, which were performed along a few cross sections in the watershed. For stochastic analysis using Monte Carlo simulation, the generated random layer thickness was made conditional to the available data from the geophysics. In order to simulate steady state flow in the irregular domain with variable geometry, we used an isoparametric finite element method to discretize the flow equation over an unstructured grid with irregular hexahedral elements. The results indicated that the spatial variability of the layer thickness had a significant effect on reducing the simulated effective steady seepage flux and that using the conditional simulations reduced the uncertainty of the simulated seepage flux. As a conclusion, combining information on the aquifer geometry obtained from geophysical surveys with stochastic modelling is a promising methodology to improve the simulation of groundwater flow in complex hard-rock aquifers.

Chaudhuri, A.; Sekhar, M.; Descloitres, M.; Godderis, Y.; Ruiz, L.; Braun, J. J.

2013-11-01

22

We present a new spatial discretization of the discrete-ordinates transport equation in two-dimensional cylindrical (RZ) geometry for arbitrary polygonal meshes. This discretization is a discontinuous finite element method that utilizes the piecewise linear basis functions developed by Stone and Adams. We describe an asymptotic analysis that shows this method to be accurate for many problems in the thick diffusion limit on arbitrary polygons, allowing this method to be applied to radiative transfer problems with these types of meshes. We also present numerical results for multiple problems on quadrilateral grids and compare these results to the well-known bi-linear discontinuous finite element method.

Bailey, T S; Adams, M L; Chang, J H

2008-10-01

23

NASA Astrophysics Data System (ADS)

Well data and core samples from the Late Paleozoic Halle Volcanic Complex (HVC) have been used to describe the geometry of the rhyolitic porphyritic laccoliths and their margins. The HVC formed between 301 and 292 Ma in the intramontane Saale basin, and it comprises mainly rhyolitic subvolcanic bodies (~300 km3) as well as minor lava flows and volcaniclastic deposits. The major HVC laccolith units display aspect ratios ranging between 0.04 and 0.07, and they are separated by tilted and deformed Carboniferous-Permian host sediments. For the margin of the Landsberg laccolith, a major coarsely porphyritic unit of the HVC, an exceptional data set of 63 wells concentrated in an area of 10 km2 reaching to depth of 710 m exists. It was used to explore the 3D geometry and textures, and to deduce an intrusion model. For a 3D visualization of the Landsberg laccolith margin, Geological Object Computer Aided Design; Paradigm® software (GOCAD) was used. Curve objects have been derived from the intrusion-host contacts. Automated GOCAD® methods for 3D modelling failed. As a result, manual refinement was essential. A major finding of the 3D modelling is the presence of prolate sediment rafts, up to 1,400 m in length and up to 500 m in thickness, surrounded by Landsberg rhyolite. The sedimentary rafts dip away from the laccolith centre. The engulfing laccolith sheets reach thickness of 100-300 m. For other HVC laccolith units (Löbejün, Petersberg, Brachstedt), well data reveal vertical rhyolite/sediment contacts or magma lobes fingering into the host sediments. HVC laccolith contact textures include small-scale shearing of the intruding magma and of the host sediment. In addition, internal shear zones have been detected inside the rhyolite bodies. The present study suggests that the emplacement of successive magma sheets was an important process during laccolith growth in the HVC.

Schmiedel, T.; Breitkreuz, C.; Görz, I.; Ehling, B.-C.

2014-11-01

24

NSDL National Science Digital Library

A short article designed to provide an introduction to geometry, including classical Euclidean geometry and synthetic (non-Euclidean) geometries; analytic geometry; incidence geometries (including projective planes); metric properties (lengths and angles); and combinatorial geometries such as those arising in finite group theory. Many results in this area are basic in either the sense of simple, or useful, or both. History; applications and related fields and subfields; textbooks, reference works, and tutorials; software and tables; other web sites with this focus.

Rusin, Dave

25

GRAPHICS PROGRAMMING Section B Java 2D

GRAPHICS PROGRAMMING Section B Â Java 2D 20 - Graphics2D: Introduction 21 - Graphics2D: Shapes 22 2D: General Path Curves 29 - Graphics 2D: Constructive Area Geometry Gary Hill December 2003 Java 2 Java initially through the Abstract Window Toolkit, which was extended to include swing, shortly

Hill, Gary

26

This article presents an analytical approach for simulation of ultrasonic diffracted wave signals from cracks in two-dimensional geometries based on a novel Huygens-Fresnel Diffraction Model (HFDM). The model employs the frequency domain far-field displacement expressions derived by Miller and Pursey in 2D for a line source located on the free surface boundary of a semi-infinite elastic medium. At each frequency in the bandwidth of a pulsed excitation, the complex diffracted field is obtained by summation of displacements due to the unblocked virtual sources located in the section containing a vertical crack. The time-domain diffracted wave signal amplitudes in a general isotropic solid are obtained by standard Fast Fourier Transform (FFT) procedures. The wedge based finite aperture transducer refracted beam profiles were modelled by treating the finite dimension transducer as an array of line sources. The proposed model is able to evaluate back-wall signal amplitude and lateral wave signal amplitude, quantitatively. The model predicted range-dependent diffracted amplitudes from the edge of a bottom surface-breaking crack in the isotropic steel specimen were compared with Geometrical Theory of Diffraction (GTD) results. The good agreement confirms the validity of the HFDM method. The simulated ultrasonic time-of-flight diffraction (TOFD) A-scan signals for surface-breaking crack lengths 2 mm and 4 mm in a 10 mm thick aluminium specimen were compared quantitatively with the experimental results. Finally, important applications of HFDM method to the ultrasonic quantitative non-destructive evaluation are discussed. PMID:25200698

Kolkoori, Sanjeevareddy; Chitti Venkata, Krishnamurthy; Balasubramaniam, Krishnan

2015-01-01

27

Application of the 2-D discrete-ordinates method to multiple scattering of laser radiation

NASA Astrophysics Data System (ADS)

The discrete-ordinates finite-element radiation transport code TWOTRAN is applied to describe the multiple scattering of a laser beam from a reflecting target. For a model scenario involving a 99 percent relative humidity rural aerosol, the average intensity of the scattered radiation and correction factors to the Beer-Lambert law arising from multiple scattering are computed. As the results indicate, 2-D x-y and r-z geometry modeling can reliably describe a realistic 3-D scenario. Specific results are presented for the two visual ranges of 1.52 and 0.76 km which show that, for sufficiently high aerosol concentrations (e.g., equivalent to V = 0.76 km), the target signature in a distant detector becomes dominated by multiply scattered radiation from interactions of the laser light with the aerosol environment. The merits of the scaling group and the delta-M approximation for the transfer equation are also explored.

Zardecki, A.; Gersti, S. A. W.; Embury, J. F.

1983-05-01

28

NASA Astrophysics Data System (ADS)

We present a semi-analytical, combinatorial approach to compute three-phase capillary entry pressures for gas invasion into pore throats with constant cross-sections of arbitrary shapes that are occupied by oil and/or water. For a specific set of three-phase capillary pressures, geometrically allowed gas/oil, oil/water and gas/water arc menisci are determined by moving two circles in opposite directions along the pore/solid boundary for each fluid pair such that the contact angle is defined at the front circular arcs. Intersections of the two circles determine the geometrically allowed arc menisci for each fluid pair. The resulting interfaces are combined systematically to allow for all geometrically possible three-phase configuration changes. The three-phase extension of the Mayer and Stowe - Princen method is adopted to calculate capillary entry pressures for all determined configuration candidates, from which the most favorable gas invasion configuration is determined. The model is validated by comparing computed three-phase capillary entry pressures and corresponding fluid configurations with analytical solutions in idealized triangular star-shaped pores. It is demonstrated that the model accounts for all scenarios that have been analyzed previously in these shapes. Finally, three-phase capillary entry pressures and associated fluid configurations are computed in throat cross-sections extracted from segmented SEM images of Bentheim sandstone. The computed gas/oil capillary entry pressures account for the expected dependence of oil/water capillary pressure in spreading and non-spreading fluid systems at the considered wetting conditions. Because these geometries are irregular and include constrictions, we introduce three-phase displacements that have not been identified previously in pore-network models that are based on idealized pore shapes. However, in the limited number of pore geometries considered in this work, we find that the favorable displacements are not generically different from those already encountered in network models previously, except that the size and shape of oil layers that are surrounded by gas and water are described more realistically. The significance of the results for describing oil connectivity in porous media accurately can only be evaluated by including throats with more complex cross-sections in three-phase pore-network models.

Zhou, Yingfang; Helland, Johan Olav; Hatzignatiou, Dimitrios G.

2014-07-01

29

ERIC Educational Resources Information Center

This article highlights how the many important contributions of John R. Z. Abela's research program can inform the development and implementation of interventions for preventing depression in youth. Abela provided evidence of multiple vulnerabilities to depression including cognitive (e.g., inferential style, dysfunctional attitudes, ruminative…

Garber, Judy; Korelitz, Katherine; Samanez-Larkin, Silvia

2012-01-01

30

The complex Pt(SnBu(t)3)2(CNBu(t))2(H)2, 1, was obtained from the reaction of Pt(COD)2 and Bu(t)3SnH, followed by addition of CNBu(t). The two hydride ligands in 1 can be eliminated, both in solution and in the solid state, to yield Pt(SnBu(t)3)2(CNBu(t))2, 2. Addition of hydrogen to 2 at room temperature in solution and in the solid state regenerates 1. Complex 2 catalyzes H2-D2 exchange in solution to give HD. The proposed mechanism of exchange involves reductive elimination of Bu(t)3SnH from 1 to afford vacant sites on the Pt center, thus facilitating the exchange process. This is supported by isolation and characterization of Pt(SnMes3)(SnBu(t)3)(CNBu(t))2, 3, when the addition of H2 to 2 was carried out in the presence of free ligand Mes3SnH (Mes = 2,4,6-Me3C6H2). Complex Pt(SnMes3)2(CNBu(t))2, 5, can be prepared from the reaction of Pt(COD)2 with Mes3SnH and CNBu(t). The exchange reaction of 2 with Ph3SnH gave Pt(SnPh3)3(CNBu(t))2(H), 6, wherein both SnBu(t)3 ligands are replaced by SnPh3. Complex 6 decomposes in air to form square planar Pt(SnPh3)2(CNBu(t))2, 7. The complex Pt(SnPr(i)3)2(CNBu(t))2, 8, was also prepared. Out of the four analogous complexes Pt(SnR3)2(CNBu(t))2 (R = Bu(t), Mes, Ph, or Pr(i)), only the Bu(t) analogue does both H2 activation and H2-D2 exchange. This is due to steric effects imparted by the bulky Bu(t) groups that distort the geometry of the complex considerably from planarity. The reaction of Pt(COD)2 with Bu(t)3SnH and CO gas afforded trans-Pt(SnBu(t)3)2(CO)2, 9. Compound 9 can be converted to 2 by replacement of the CO ligands with CNBu(t) via the intermediate Pt(SnBu(t)3)2(CNBu(t))2(CO), 10. PMID:25539155

Koppaka, Anjaneyulu; Zhu, Lei; Yempally, Veeranna; Isrow, Derek; Pellechia, Perry J; Captain, Burjor

2015-01-14

31

NASA Astrophysics Data System (ADS)

For many plasma physics problems, three-dimensional and kinetic effects are very important. However, such simulations are very computationally intensive. Fortunately, there is a class of problems for which there is nearly azimuthal symmetry and the dominant three-dimensional physics is captured by the inclusion of only a few azimuthal harmonics. Recently, it was proposed [1] to model one such problem, laser wakefield acceleration, by expanding the fields and currents in azimuthal harmonics and truncating the expansion. The complex amplitudes of the fundamental and first harmonic for the fields were solved on an r-z grid and a procedure for calculating the complex current amplitudes for each particle based on its motion in Cartesian geometry was presented using a Marder's correction to maintain the validity of Gauss's law. In this paper, we describe an implementation of this algorithm into OSIRIS using a rigorous charge conserving current deposition method to maintain the validity of Gauss's law. We show that this algorithm is a hybrid method which uses a particles-in-cell description in r-z and a gridless description in ?. We include the ability to keep an arbitrary number of harmonics and higher order particle shapes. Examples for laser wakefield acceleration, plasma wakefield acceleration, and beam loading are also presented and directions for future work are discussed.

Davidson, A.; Tableman, A.; An, W.; Tsung, F. S.; Lu, W.; Vieira, J.; Fonseca, R. A.; Silva, L. O.; Mori, W. B.

2015-01-01

32

MULTI2D - a computer code for two-dimensional radiation hydrodynamics

NASA Astrophysics Data System (ADS)

Simulation of radiation hydrodynamics in two spatial dimensions is developed, having in mind, in particular, target design for indirectly driven inertial confinement energy (IFE) and the interpretation of related experiments. Intense radiation pulses by laser or particle beams heat high-Z target configurations of different geometries and lead to a regime which is optically thick in some regions and optically thin in others. A diffusion description is inadequate in this situation. A new numerical code has been developed which describes hydrodynamics in two spatial dimensions (cylindrical R-Z geometry) and radiation transport along rays in three dimensions with the 4 ? solid angle discretized in direction. Matter moves on a non-structured mesh composed of trilateral and quadrilateral elements. Radiation flux of a given direction enters on two (one) sides of a triangle and leaves on the opposite side(s) in proportion to the viewing angles depending on the geometry. This scheme allows to propagate sharply edged beams without ray tracing, though at the price of some lateral diffusion. The algorithm treats correctly both the optically thin and optically thick regimes. A symmetric semi-implicit (SSI) method is used to guarantee numerical stability. Program summaryProgram title: MULTI2D Catalogue identifier: AECV_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AECV_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 151 098 No. of bytes in distributed program, including test data, etc.: 889 622 Distribution format: tar.gz Programming language: C Computer: PC (32 bits architecture) Operating system: Linux/Unix RAM: 2 Mbytes Word size: 32 bits Classification: 19.7 External routines: X-window standard library (libX11.so) and corresponding heading files (X11/*.h) are required. Nature of problem: In inertial confinement fusion and related experiments with lasers and particle beams, energy transport by thermal radiation becomes important. Under these conditions, the radiation field strongly interacts with the hydrodynamic motion through emission and absorption processes. Solution method: The equations of radiation transfer coupled with Lagrangian hydrodynamics, heat diffusion and beam tracing (laser or ions) are solved, in two-dimensional axial-symmetric geometry ( R-Z coordinates) using a fractional step scheme. Radiation transfer is solved with angular resolution. Matter properties are either interpolated from tables (equations-of-state and opacities) or computed by user routines (conductivities and beam attenuation). Restrictions: The code has been designed for typical conditions prevailing in inertial confinement fusion (ns time scale, matter states close to local thermodynamical equilibrium, negligible radiation pressure, …). Although a wider range of situations can be treated, extrapolations to regions beyond this design range need special care. Unusual features: A special computer language, called r94, is used at top levels of the code. These parts have to be converted to standard C by a translation program (supplied as part of the package). Due to the complexity of code (hydro-code, grid generation, user interface, graphic post-processor, translator program, installation scripts) extensive manuals are supplied as part of the package. Running time: 567 seconds for the example supplied.

Ramis, R.; Meyer-ter-Vehn, J.; Ramírez, J.

2009-06-01

33

Symplectic Geometry Metric geometry

surfaces, metric space geometry, as well as the analytic/algebraic geometry of curvature, characteristicBasics Symplectic Geometry Curvature Metric geometry Random geodesics Weil-Petersson sampler;Basics Symplectic Geometry Curvature Metric geometry Random geodesics Table of contents 1 Introduction

Wolpert, Scott A.

34

\\u000a An overview of selected topics in face recognition is first presented in this chapter. The BioSecure 2D-face Benchmarking\\u000a Framework is also described, composed of open-source software, publicly available databases and protocols. Three methods for\\u000a 2D-face recognition, exploiting multiscale analysis, are presented. The first method exploits anisotropic smoothing, combined\\u000a Gabor features and Linear Discriminant Analysis (LDA). The second approach is based

Massimo Tistarelli; Manuele Bicego; José L. Alba-Castro; Daniel Gonzàlez-Jiménez; Mohamed-Anouar Mellakh; Albert Ali Salah; Dijana Petrovska-Delacrétaz; Bernadette Dorizzi; G. Chollet

2008-01-01

35

This paper presents a validation of numerical simulations in case of a forced oscillating hydrofoil. As a representative case study for vibrating blade in hydraulics machines, a 2D NACA 0009 oscillating hydrofoil is considered. Pressure coefficients from experiments and numerical simulations are presented. The fluid torque is then investigated in the frequency domain. A good agreement between experiments and numerical

Cecile MÜNCH; Philippe AUSONI; Mohamed FARHAT; François AVELLAN

36

The Sphinx machine based on microsecond LTD technology was used to implode single wire arrays. These z-pinch experiments were performed on Sphinx driver using a multi-microsecond current prepulse. This prepulse dramatically changes the ablation phase leading to an improvement of the axial homogeneity of both the implosion and the final radiating column. As a consequence, the number of parameters and

J. Grunenwald; H. Calamy; F. Lassalle; F. Zucchini; A. Loyen; P. Maury; A. Georges; A. Morell; J. P. Bedoch

2008-01-01

37

NASA Astrophysics Data System (ADS)

We make a detailed study of the infinite dimensional Galilean Conformal Algebra (GCA) in the case of two spacetime dimensions. Classically, this algebra is precisely obtained from a contraction of the generators of the relativistic conformal symmetry in 2 d. Here we find quantum mechanical realisations of the (centrally extended) GCA by considering scaling limits of certain 2d CFTs. These parent CFTs are non-unitary and have their left and right central charges become large in magnitude and opposite in sign. We therefore develop, in parallel to the usual machinery for 2 d CFT, many of the tools for the analysis of the quantum mechanical GCA. These include the representation theory based on GCA primaries, Ward identities for their correlation functions and a nonrelativistic Kac table. In particular, the null vectors of the GCA lead to differential equations for the four point function. The solution to these equations in the simplest case is explicitly obtained and checked to be consistent with various requirements.

Bagchi, Arjun; Gopakumar, Rajesh; Mandal, Ipsita; Miwa, Akitsugu

2010-08-01

38

Modeling the longitudinal wall impedance instability in heavy ion beams using an R-Z PIC code

The effects of the longitudinal wall impedance instability in a heavy ion beam are of great interest for heavy ion fusion drivers. We are studying this instability using the R-Z thread of the WARP PIC code. We describe the code and our model of the impedance due to the accelerating modules of the induction LINAC as a resistive wall. We present computer simulations which illustrate this instability. 2 refs., 2 figs., 1 tab.

Callahan, D.A.; Langdon, A.B.; Friedman, A.; Grote, D.P. (Lawrence Livermore National Lab., CA (USA)); Haber, I. (Naval Research Lab., Washington, DC (USA))

1991-02-22

39

Lectures on 2D gravity and 2D string theory

This report discusses the following topics: loops and states in conformal field theory; brief review of the Liouville theory; 2D Euclidean quantum gravity 1 -- path integral approach; 2D Euclidean quantum gravity 2 -- canonical approach; states in 2D string theory; matrix model technology 1 -- method of orthogonal polynomials; matrix model technology 2 -- loops on the lattice; matrix

P. Ginsparg; Gregory Moore

1992-01-01

40

rlr >vJ-l.r-z z1 3 THE DYNAMTCBEHAVIOUR OF THE STALL_REGULATEDNIBE A WIND

rlr >vJ-l.r- z z1 3 THE DYNAMTCBEHAVIOUR OF THE STALL_REGULATEDNIBE A WIND TURBINE. I'IEASUREMENTSAND A MODEL I'OR STALL-INDUCED VIBRATIONS P . L u n d s a g e r, ; . 1 .P e t e r s e n , a n d S . F r a n d. INTRODUCTION 4 3 4 B 2. MEASUREMENTSMADE APR]L I9BO 4 B #12;Page 3 . SINGLE DEGREE OF .b-REEDOMMODEL FOR STALL

41

The kinetic processes occurring in an electric-discharge oxygen-iodine laser are analyzed with the help of a 2D (r, z) gasdynamic model taking into account transport of excited oxygen, singlet oxygen, and radicals from the electric discharge\\u000a and their mixing with the iodine-containing gas. The main processes affecting the dynamics of the gas temperature and gain\\u000a are revealed. The simulation results

A. A. Chukalovsky; T. V. Rakhimova; K. S. Klopovsky; Yu. A. Mankelevich; O. V. Proshina

2011-01-01

42

What we've learned from 3-D and r,z intense-beam simulations using the WARP code

We describe a multi-dimensional discrete-particle simulation code, WARP, and its application to Heavy Ion Fusion beams. The code's 3-D package combines features of an accelerator code and a particle-in-cell plasma simulation, and can efficiently track beams through many lattice elements and around bends. The code's r, z package allows us to follow beams over very long times and models the accelerating module impedances. A number of applications are presented. These have led to an improved understanding of: Beam equilibria, and the approach to equilibrium; longitudinal beam dynamics and stability; electrostatic quadrupole (ESQ) injector aberrations; bending and recirculation of space-charge-dominated beams; and the drift-compression process. The code is being used for accelerator design, as well as for theoretical investigations.

Friedman, A.; Callahan, D.A.; Grote, D.P.; Langdon, A.B.; Lund, S.M. (Lawrence Livermore National Lab., CA (United States)); Haber, I. (Naval Research Lab., Washington, DC (United States))

1993-05-06

43

The Conformal Mode in 2D Simplicial Gravity

We verify that summing 2D DT geometries correctly reproduces the Polyakov action for the conformal mode, including all ghost contributions, at large volumes. The Gaussian action is reproduced even for c=10, well into the branched polymer phase, which confirms the expectation that the DT measure is indeed correct in this regime as well.

S. Catterall; E. Mottola

1999-06-26

44

Coupled electron\\/photon S[sub N] calculation in lattice geometry

The capabilities of the SMARTEPANTS (Simulating Many Accumulative Rutherford Trajectories Electron Photon and Neutral Transport Solver)-coupled charged\\/neutral particle transport S[sub N] Code have been extended from r-z and x-y-z geometry to x-y-z geometry with embedded cylinder. The basic idea is to accommodate cylindrical shapes using a rectangular mesh. To do this, the code allows for the replacement of any number

K. Hadad; W. L. Filippone

1993-01-01

45

NSDL National Science Digital Library

The EJS Random Walk 2D Model simulates a 2-D random walk. You can change the number of walkers and probability of going a given direction. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. The Random Walk 2D Model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_RandomWalk2D.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2009-04-27

46

sur l'lÂ·levage des Povcs, 1. N. R. A., C. N. R. Z., 78350 Jouy en .T osas With a view to estimating. They were fed individually according to a restriction schedule depending on live weight and different intake performances (daily mean gain DMG : 692 g ; feed conversion ratio FCR : 2-40) as those obtained

Paris-Sud XI, UniversitÃ© de

47

in matematica, fisica e filosofia V e n e r d i 2 6 M a r z o 2 0 0 4

LÃ?infinito in matematica, fisica e filosofia V e n e r d i 2 6 M a r z o 2 0 0 4 curatori: Vieri, UniversitÃ di Pisa Lucio Russo Dip. Matematica dell'UniversitÃ di Roma II Steven Shore Dip. Fisica Carlo Toffalori Dip. Matematica e Fisica, UniversitÃ di Camerino Vieri Benci Dip. Matematica Applicata

Di Nasso, Mauro

48

2D unitary ESPRIT for efficient 2D parameter estimation

Considers multiple narrowband signals that are incident upon a planar sensor array. 2D unitary ESPRIT is a new closed-form high resolution algorithm to provide automatically paired source azimuth and elevation angle estimates along with an efficient way to reconstruct the impinging signals. In the final stage of the algorithm, the real and imaginary parts of the ith eigenvalue of a

Martin Haardt; Michael D. Zoltowski; C. P. Mathews; J. A. Nossek

1995-01-01

49

NSDL National Science Digital Library

The STP Ising2D program is a Monte Carlo simulation of a two-dimensional Ising model in equilibrium with a heat bath at temperature T using the Metropolis or Wolff algorithms. The default is a lattice of linear dimension L=32 (for a total of N=L^2 spins) with no external field and heat bath temperature T=0. STP Ising2D is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double clicking the stp_Ising2D.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2008-05-28

50

NSDL National Science Digital Library

The QM Probability 2D program displays the time evolution of the two-dimensional probability density using color to represent its magnitude. The default wave function is a two-state superposition in the x (nx = 1,2) and y dimension (ny = 3,4) state in an infinite square well. Additional states and other potential energy functions can be specified using the Display | Switch GUI menu item. QM Probability 2D is one of 18 Open Source Physics programs that model time-dependent quantum mechanics using an energy eigenstate expansion. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the qm_probability_2d.jar file will run the program if Java is installed. Other programs provide additional visualizations. They can be found by searching ComPADRE for Open Source Physics, OSP, or Superposition.

Christian, Wolfgang

2008-05-20

51

Compatible, energy and symmetry preserving 2D Lagrangian hydrodynamics in rz-cylindrical coordinates

We present a new discretization for 2D Lagrangian hydrodynamics in rz geometry (cylindrical coordinates) that is compatible, energy conserving and symmetry preserving. We describe discretization of the basic Lagrangian hydrodynamics equations.

Shashkov, Mikhail [Los Alamos National Laboratory; Wendroff, Burton [Los Alamos National Laboratory; Burton, Donald [Los Alamos National Laboratory; Barlow, A [AWE; Hongbin, Guo [ASU

2009-01-01

52

2D Gaussian distributions. Equal height.

2D Gaussian distributions. Equal height. Noise-free. Well separated. #12;2D Gaussian distributions. Equal height. Noise-free. Well separated. #12;2D Gaussian distributions. Equal height. Noise-free. Somewhat separated. #12;2D Gaussian distributions. Equal height. Noise-free. Overlapping. #12;2D Gaussian

Oakes, Terry

53

NASA Astrophysics Data System (ADS)

In this Letter, 2D Dirac oscillator in the quantum deformed framework generated by the ?-Poincaré-Hopf algebra is considered. The problem is formulated using the ?-deformed Dirac equation. The resulting theory reveals that the energies and wave functions of the oscillator are modified by the deformation parameter.

Andrade, Fabiano M.; Silva, Edilberto O.

2014-11-01

54

Design of optimal and ideal 2-D concentrators with the collector immersed in a dielectric tube

A method is presented for designing ideal and optimal 2-D concentrators when the collector is placed inside a dielectric tube, for the particular case of a bifacial solar collector. The prototype 2-D (cylindrical geometry) concentrator is the compound parabolic concentrator or CPC, and from the beginning of development, it was found by Winston (1978) that filling up the concentrator with

J. C. Minano; J. M. Ruiz; A. Luque

1983-01-01

55

Pythagoras' Theorem on a 2D-Lattice from a \\

One of the key ingredients of A. Connes' noncommutative geometry is a\\u000ageneralized Dirac operator which induces a metric(Connes' distance) on the\\u000astate space. We generalize such a Dirac operator devised by A. Dimakis et al,\\u000awhose Connes' distance recovers the linear distance on a 1D lattice, into 2D\\u000alattice. This Dirac operator being \\

Jian Dai; Xing-Chang Song

2001-01-01

56

2D Euclidean distance transform algorithms: A comparative survey

The distance transform (DT) is a general operator forming the basis of many methods in computer vision and geometry, with great potential for practical applications. However, all the optimal algorithms for the computation of the exact Euclidean DT (EDT) were proposed only since the 1990s. In this work, state-of-the- art sequential 2D EDT algorithms are reviewed and compared, in an

Ricardo Fabbri; Luciano Da Fontoura Costa; Julio C. Torelli; Odemir Martinez Bruno

2008-01-01

57

Numerical evaluation of hierarchical vector finite elements on curvilinear domains in 2-D

When using the finite element method, computational efficiency may be improved by using higher order elements. Typical 2-D triangular rectilinear elements cannot exactly model curved geometries, negating the advantage of higher order elements when such geometries are modeled. Curvilinear elements can be applied to such problems, and have significantly better computational efficiency than rectilinear elements when higher order elements are

N. Marais; D. B. Davidson

2006-01-01

58

NASA Astrophysics Data System (ADS)

We probe the jamming of 2D wet foams by lateral compression of a bidisperse foam monolayer sandwiched between a glass plate and a fluid surface. Boundaries and residual gravitational effects prevent the foam to be truly unjammed, obstructing the observation of a jammed/unjammed transition. Instead, we find a clear transition from a ``gravity jammed'' to a ``boundary jammed'' state, where the bulk modulus jumps from essentially zero to a finite value, in agreement with theory. In addition, we probe the nonaffine bubble motion, which becomes large near this transition.

Siemens, Alexander; van Hecke, Martin

2013-03-01

59

2D quasiperiodic plasmonic crystals

Nanophotonic structures with irregular symmetry, such as quasiperiodic plasmonic crystals, have gained an increasing amount of attention, in particular as potential candidates to enhance the absorption of solar cells in an angular insensitive fashion. To examine the photonic bandstructure of such systems that determines their optical properties, it is necessary to measure and model normal and oblique light interaction with plasmonic crystals. We determine the different propagation vectors and consider the interaction of all possible waveguide modes and particle plasmons in a 2D metallic photonic quasicrystal, in conjunction with the dispersion relations of a slab waveguide. Using a Fano model, we calculate the optical properties for normal and inclined light incidence. Comparing measurements of a quasiperiodic lattice to the modelled spectra for angle of incidence variation in both azimuthal and polar direction of the sample gives excellent agreement and confirms the predictive power of our model. PMID:23209871

Bauer, Christina; Kobiela, Georg; Giessen, Harald

2012-01-01

60

Ultrafast 2D IR Vibrational Echo Spectroscopy

Ultrafast 2D IR Vibrational Echo Spectroscopy JUNRONG ZHENG, KYUNGWON KWAK, AND M. D. FAYER The experimental technique and applications of ultrafast two- dimensional infrared (2D IR) vibrational echo spectrum of a mixture of species. I. Introduction Ultrafast 2D IR vibrational echo spectroscopy1

Fayer, Michael D.

61

2-D and 3-D computations of curved accelerator magnets

In order to save computer memory, a long accelerator magnet may be computed by treating the long central region and the end regions separately. The dipole magnets for the injector synchrotron of the Advanced Photon Source (APS), now under construction at Argonne National Laboratory (ANL), employ magnet iron consisting of parallel laminations, stacked with a uniform radius of curvature of 33.379 m. Laplace's equation for the magnetic scalar potential has a different form for a straight magnet (x-y coordinates), a magnet with surfaces curved about a common center (r-{theta} coordinates), and a magnet with parallel laminations like the APS injector dipole. Yet pseudo 2-D computations for the three geometries give basically identical results, even for a much more strongly curved magnet. Hence 2-D (x-y) computations of the central region and 3-D computations of the end regions can be combined to determine the overall magnetic behavior of the magnets. 1 ref., 6 figs.

Turner, L.R.

1991-01-01

62

TRO-2D - A code for rational transonic aerodynamic optimization

NASA Technical Reports Server (NTRS)

Features and sample applications of the transonic rational optimization (TRO-2D) code are outlined. TRO-2D includes the airfoil analysis code FLO-36, the CONMIN optimization code and a rational approach to defining aero-function shapes for geometry modification. The program is part of an effort to develop an aerodynamically smart optimizer that will simplify and shorten the design process. The user has a selection of drag minimization and associated minimum lift, moment, and the pressure distribution, a choice among 14 resident aero-function shapes, and options on aerodynamic and geometric constraints. Design variables such as the angle of attack, leading edge radius and camber, shock strength and movement, supersonic pressure plateau control, etc., are discussed. The results of calculations of a reduced leading edge camber transonic airfoil and an airfoil with a natural laminar flow are provided, showing that only four design variables need be specified to obtain satisfactory results.

Davis, W. H., Jr.

1985-01-01

63

NASA Astrophysics Data System (ADS)

For the diagnosis of ischemic heart disease, accurate quantitative analysis of the coronary arteries is important. In coronary angiography, a number of projections is acquired from which 3D models of the coronaries can be reconstructed. A signifcant limitation of the current 3D modeling procedures is the required user interaction for defining the centerlines of the vessel structures in the 2D projections. Currently, the 3D centerlines of the coronary tree structure are calculated based on the interactively determined centerlines in two projections. For every interactively selected centerline point in a first projection the corresponding point in a second projection has to be determined interactively by the user. The correspondence is obtained based on the epipolar-geometry. In this paper a method is proposed to retrieve all the information required for the modeling procedure, by the interactive determination of the 2D centerline-points in only one projection. For every determined 2D centerline-point the corresponding 3D centerline-point is calculated by the analysis of the 1D gray value functions of the corresponding epipolarlines in space for all available 2D projections. This information is then used to build a 3D representation of the coronary arteries using coronary modeling techniques. The approach is illustrated on the analysis of calibrated phantom and calibrated coronary projection data.

Movassaghi, Babak; Rasche, Volker; Viergever, Max A.; Niessen, Wiro J.

2004-05-01

64

This paper introduces the concept of Geometry Compression, al- lowing 3D triangle data to be represented with a factor of 6 to 10 times fewer bits than conventional techniques, with only slight loss- es in object quality. The technique is amenable to rapid decompres- sion in both software and hardware implementations; if 3D render- ing hardware contains a geometry decompression

Michael Deering

1995-01-01

65

Structure of the novel ternary hydrides Li4Tt2D (Tt=Si and Ge).

The crystal structures of newly discovered Li4Ge2D and Li4Si2D ternary phases were solved by direct methods using neutron powder diffraction data. Both structures can be described using a Cmmm orthorhombic cell with all hydrogen atoms occupying Li6-octahedral interstices. The overall crystal structure and the geometry of these interstices are compared with those of other related phases, and the stabilization of this novel class of ternary hydrides is discussed. PMID:17235195

Wu, Hui; Hartman, Michael R; Udovic, Terrence J; Rush, John J; Zhou, Wei; Bowman, Robert C; Vajo, John J

2007-02-01

66

VECTUM. Irregular 2D Velocity Vector Field Plotting Package

VECTUM is a NCAR Graphics based package, for generating a plot of an irregular 2D velocity vector field. The program reads an ASCII database of x, y, u, v, data pairs and produces a plot in Computer Graphics Metafile (CGM) format. The program also uses an ASCII parameter file for controlling annotation details such as the plot title, arrowhead style, scale of vectors, windowing, etc. Simple geometry (i.e. lines, arcs, splines) can be defined to be included with the velocity vectors. NCAR Graphics drivers can be used to display the CGM file into PostScript, HPGL, HDF, etc, output.

McClurg, F.R.; Mousseau, V.A. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

1992-05-04

67

NKG2D signaling in cancer immunosurveillance.

The immune system is able to detect and eliminate transformed cells. The activating receptor NKG2D is particularly relevant for cancer immunosurveillance. NKG2D ligand expression renders tumor cells more susceptible to be killed by NK and T cells, and correlates with the clinical outcome of the disease. However, tumors develop mechanisms to overcome the NKG2D-mediated immune response, which has been associated with poor prognosis and impairment of the clinical benefits of immunotherapy in many human cancers. The highly specific pattern of expression displayed by the NKG2D ligands, mainly confined to tumor cells, together with the strong immune response triggered by this receptor clearly supports the idea that the NKG2D-mediated pathway may be a powerful target for the treatment of cancer. This review draws together the most recent discoveries concerning the biology of the NKG2D signaling and their therapeutic relevance in the context of cancer. PMID:24615398

López-Soto, Alejandro; Huergo-Zapico, Leticia; Acebes-Huerta, Andrea; Villa-Alvarez, Mónica; Gonzalez, Segundo

2015-04-15

68

Capturing nonlocal effects in 2D granular flows

NASA Astrophysics Data System (ADS)

There is an industrial need, and a scientific desire, to produce a continuum model that can predict the flow of dense granular matter in an arbitrary geometry. A viscoplastic continuum approach, developed over recent years, has shown some ability to approximate steady flow and stress profiles in multiple inhomogeneous flow environments. However, the model incorrectly represents phenomena observed in the slow, creeping flow regime. As normalized flow-rate decreases, granular stresses are observed to become largely rate-independent and a dominating length-scale emerges in the mechanics. This talk attempts to account for these effects, in the simplified case of 2D, using the notion of nonlocal fluidity, which has proven successful in treating nonlocal effects in emulsions. The idea is to augment the local granular fluidity law with a diffusive second-order term scaled by the particle size, which spreads flowing zones accordingly. Below the yield stress, the local contribution vanishes and the fluidity becomes rate-independent, as we require. We implement the modified law in multiple geometries and validate its flow and stress predictions in multiple geometries compared against discrete particle simulations. In so doing, we demonstrate that the nonlocal relation proposed is satisfied universally in a seemingly geometry-independent fashion.

Kamrin, Ken; Koval, Georg

2013-03-01

69

Geometry of Generalized Depolarizing Channels

A generalized depolarizing channel acts on an N-dimensional quantum system to compress the ``Bloch ball'' in N^2-1 directions; it has a corresponding compression vector. We investigate the geometry of these compression vectors and prove a conjecture of Dixit and Sudarshan [1], namely that when N=2^d (i.e. the system consists of d qubits) and we work in the Pauli basis then the set of all compression vectors forms a simplex. We extend this result by investigating the geometry in other bases; in particular we find precisely when the set of all compression vectors forms a simplex.

Christian K. Burrell

2009-09-10

70

\\u000a In the thirties of the 19th century János Bolyai and Nikolai Ivanovi? Lobacevskii created the hyperbolic geometry. Thus they proved that not only the\\u000a Euclidean but also other geometries may exist. Concerning its geometrical importance, this discovery can be compared to the\\u000a change which replaced the Ptolemaic geocentric concept of astronomy by the heliocentric point of view of Copernicus. Hyperbolic

Lajos Tamássy

71

Algebra = Geometry Sandor Kovacs

Algebra = Geometry SÂ´andor KovÂ´acs University of Washington #12;Motto "To me, algebraic geometry is algebra with a kick" ÂSolomon Lefschetz #12;Geometry Geometry = Space + Functions #12;Geometry Geometry = Space + Functions Type of function Type of Geometry #12;Geometry Geometry = Space + Functions Type

KovÃ¡cs, SÃ¡ndor

72

Image Representation Using 2D Gabor Wavelets

This paper extends to two dimensions the frame criterion developed by Daubechies for one-dimensional wavelets, and itcomputes the frame bounds for the particular case of 2D Gabor wavelets. Completeness criteria for 2D Gabor imagerepresentations are important because of their increasing role in many computer vision applications and also in modeling biologicalvision, since recent neurophysiological evidence from the visual cortex of

Tai Sing Lee

1996-01-01

73

2D conglomerate crystallization of heptahelicene.

Two-dimensional (2D) nucleation and crystallization of the helical aromatic hydrocarbon heptahelicene on the single crystalline copper(100) surface has been studied with scanning tunnelling microscopy. In contrast to previously observed racemic 2D crystals on Cu(111), separation into homochiral domains is observed for Cu(100). PMID:24968343

Seibel, Johannes; Zoppi, Laura; Ernst, Karl-Heinz

2014-08-14

74

Staring 2-D hadamard transform spectral imager

A staring imaging system inputs a 2D spatial image containing multi-frequency spectral information. This image is encoded in one dimension of the image with a cyclic Hadamarid S-matrix. The resulting image is detecting with a spatial 2D detector; and a computer applies a Hadamard transform to recover the encoded image.

Gentry, Stephen M. (Albuquerque, NM); Wehlburg, Christine M. (Albuquerque, NM); Wehlburg, Joseph C. (Albuquerque, NM); Smith, Mark W. (Albuquerque, NM); Smith, Jody L. (Albuquerque, NM)

2006-02-07

75

Design Application Translates 2-D Graphics to 3-D Surfaces

NASA Technical Reports Server (NTRS)

Fabric Images Inc., specializing in the printing and manufacturing of fabric tension architecture for the retail, museum, and exhibit/tradeshow communities, designed software to translate 2-D graphics for 3-D surfaces prior to print production. Fabric Images' fabric-flattening design process models a 3-D surface based on computer-aided design (CAD) specifications. The surface geometry of the model is used to form a 2-D template, similar to a flattening process developed by NASA's Glenn Research Center. This template or pattern is then applied in the development of a 2-D graphic layout. Benefits of this process include 11.5 percent time savings per project, less material wasted, and the ability to improve upon graphic techniques and offer new design services. Partners include Exhibitgroup/Giltspur (end-user client: TAC Air, a division of Truman Arnold Companies Inc.), Jack Morton Worldwide (end-user client: Nickelodeon), as well as 3D Exhibits Inc., and MG Design Associates Corp.

2007-01-01

76

Reducing the computational complexity of narrowband 2D fan filters using shaped 2D window functions

Two-dimensional (2D) discrete-domain FIR narrow fan filters may be used for the selective filtering of sampled broadband 2D plane waves on the basis of their directions of arrival (DOA). We show that the 2D region of support (ROS) of the unit impulse response h(n1,n2) of such filters may be reduced in size by using a shaped 2D window function, where

Leila Khademi; Leonard T. Bruton

2003-01-01

77

NETGEN -An Advancing Front 2D/3D-Mesh Generator Based on Abstract Rules

NETGEN - An Advancing Front 2D/3D-Mesh Generator Based on Abstract Rules Joachim Schoberl Abstract In this paper, the algorithms of the automatic mesh generator NETGEN are described. The domain is provided by a Constructive Solid Geometry (CSG). The whole task of 3D mesh generation splits into four subproblems of special

Schoeberl, Joachim

78

2D and 3D Method of Characteristic Tools for Complex Nozzle Development

NASA Technical Reports Server (NTRS)

This report details the development of a 2D and 3D Method of Characteristic (MOC) tool for the design of complex nozzle geometries. These tools are GUI driven and can be run on most Windows-based platforms. The report provides a user's manual for these tools as well as explains the mathematical algorithms used in the MOC solutions.

Rice, Tharen

2003-01-01

79

NSDL National Science Digital Library

A short article designed to provide an introduction to algebraic geometry, which combines the algebraic with the geometric for the benefit of both. Thus the recent proof of "Fermat's Last Theorem" - ostensibly a statement in number theory - was proved with geometric tools. Conversely, the geometry of sets defined by equations is studied using quite sophisticated algebraic machinery. This is an enticing area but the important topics are quite deep. This area includes elliptic curves. Applications and related fields and subfields; textbooks, reference works, and tutorials; software and tables; other web sites with this focus.

Rusin, David J., 1957-

2007-12-18

80

Comparison of ultrasound tomography methods in circular geometry

Extremely high quality data was acquired using an experimental ultrasound scanner developed at Lawrence Livermore National Laboratory using a 2D ring geometry with up to 720 transmitter\\/receiver transducer positions. This unique geometry allows reflection and transmission modes and transmission imaging and quantification of a 3D volume using 2D slice data. Standard image reconstruction methods were applied to the data including

Richard Leach; Steve G. Azevedo; James G. Berryman; Hugo Bertete-Aguirre; David H. Chambers; Jeffrey E. Mast; Peter J. Littrup; Nebojsa Duric; Steven A. Johnson; Frank Wuebbeling

2002-01-01

81

Robust Mixed Filtering of 2-D Systems

Abstract—This paper deals with several challenging problems of robust filtering for two-dimensional (2-D) systems. First of all, new linear matrix inequality (LMI) characterizations for the and,norms of 2-D systems are introduced and thoroughly es- tablished. Based on these preparatory results, convex (LMI) char- acterizations for robust , , and robust mixed fil- tering are derived. The efficiency and viability of

Hoang Duong Tuan; Pierre Apkarian; Truong Q. Nguyen; Tatsuo Narikiyo

82

Finite Heat conduction in 2D Lattices

This paper gives a 2D hamonic lattices model with missing bond defects, when the capacity ratio of defects is enough large, the temperature gradient can be formed and the finite heat conduction is found in the model. The defects in the 2D harmonic lattices impede the energy carriers free propagation, by another words, the mean free paths of the energy carrier are relatively short. The microscopic dynamics leads to the finite conduction in the model.

Lei Yang; Yang Kongqing

2001-07-30

83

NASA Technical Reports Server (NTRS)

A two-dimensional computational code, PRLUS2D, which was developed for the reactive propulsive flows of ramjets and scramjets, was validated for two-dimensional shock-wave/turbulent-boundary-layer interactions. The problem of compression corners at supersonic speeds was solved using the RPLUS2D code. To validate the RPLUS2D code for hypersonic speeds, it was applied to a realistic hypersonic inlet geometry. Both the Baldwin-Lomax and the Chien two-equation turbulence models were used. Computational results showed that the RPLUS2D code compared very well with experimentally obtained data for supersonic compression corner flows, except in the case of large separated flows resulting from the interactions between the shock wave and turbulent boundary layer. The computational results compared well with the experiment results in a hypersonic NASA P8 inlet case, with the Chien two-equation turbulence model performing better than the Baldwin-Lomax model.

Kapoor, Kamlesh; Anderson, Bernhard H.; Shaw, Robert J.

1994-01-01

84

Optical diffraction from opal-based photonic structures: transition from 2D to 3D regimes

NASA Astrophysics Data System (ADS)

We report on experimental and theoretical investigations of light diffraction from opal films of different thickness. A special attention was paid to the transformation of diffraction patterns upon building up the opal structure from two-dimensional (2D) film structure towards bulk three-dimensional (3D) structure. In our setup the diffraction patterns are displayed on a narrow cylindrical screen with a specimen fixed in its center. The diffraction patterns have been studied visually and recorded in different scattering geometries with the films illuminated with white unpolarized light. With increasing number of layers, certain regions of 2D diffraction patterns fade out and finally form diffraction spots characteristic for 3D diffraction. We also found that stacking faults in bulk opals lead to formation of a 2D-like diffraction pattern, i.e. such structure demonstrate 3D to quasi-2D transition in optical properties.

Sinev, Ivan S.; Rybin, Mikhail V.; Samusev, Anton K.; Samusev, Kirill B.; Trofimova, Ekaterina Y.; Kurdukov, Dmitry A.; Golubev, Valery G.; Limonov, Mikhail F.

2012-06-01

85

Using a primer set designed on the cDNA encoding the known marmoset cytochrome P450 2D19 (CYP2D19), a cDNA encoding a novel CYP2D enzyme (CYP2D30) was cloned from the liver of a female marmoset bred at Kyoto University (KYU). In addition, a cDNA encoding CYP2D19 was cloned from the liver of a female marmoset bred at Kagoshima University (KAU). CYP2D30 and

Hiroyuki Hichiya; Shino Kuramoto; Shigeo Yamamoto; Sumio Shinoda; Nobumitsu Hanioka; Shizuo Narimatsu; Kazuo Asaoka; Atsuro Miyata; Shinichi Iwata; Masahiro Nomoto; Tetsuo Satoh; Kimio Kiryu; Nobuhiko Ueda; Shinsaku Naito; Geoffrey T. Tucker; S. Wynne Ellis

2004-01-01

86

NASA Astrophysics Data System (ADS)

Assuming axial symmetry and a uniform power input, a 2D model (r, z) is developed numerically for determination of the gas temperature in the case of a nanosecond pulsed longitudinal discharge in He-SrBr2 formed in a newly-designed large-volume high-temperature discharge tube with additional incompact ZrO2 insulation in the discharge-free zone, in order to find the optimal thermal mode for achievement of maximal output laser parameters. The model determines the gas temperature of a nanosecond pulsed longitudinal discharge in helium with small additives of strontium and bromine.

Chernogorova, T. P.; Temelkov, K. A.; Koleva, N. K.; Vuchkov, N. K.

2014-05-01

87

NSDL National Science Digital Library

This is a web site to support a first course in fractal geometry for students without a strong mathematical background. It covers a wide range of topics in fractals, modern dynamics, and chaos. Each of the topics contains examples of fractals in the arts, humanities, or social sciences. The site also contains lesson plans and software that can be used for a broad range of classes.

Frame, Michael; Mandelbrot, Benoit

2004-11-30

88

Interpretive 2-D treatment of scrape-off-layer plasmas

The width of the scrape-off-layer in a tokamak is determined by cross field transport. In Alcator C-mod the plasma parameters in the scrape-off-layer are measured at upstream and divertor plate locations. We solve a 2-D scrape-off-layer heat conduction equation in the flux geometry (as determined by EFIT) of the C-mod experiment. Bolometric measurements are utilized for the radiative loss term. We use the end wall probe measurements of electron temperature as a boundary condition and the fast scanning probe measurements of upstream temperature are treated as constraints to determine the cross field transport and thermal conductivity. Results are compared with 1-D onion-skin-model predictions.

Umansky, M.; Allen, A.; Daughton, W. [MIT Plasma Fusion Center, Cambridge, MA (United States)] [and others

1996-12-31

89

Thin films versus 2D sheets in layered structures: graphene and 2D metallic sheets

We study an interface between two media separated by a strictly 2D sheet. We show how the amplitude reflection coefficient can be modeled by that for an interface where the 2D sheet has been replaced by a film of small but finite thickness. We give the relationship between the 3D dielectric function of the thin film and the 2D dielectric function of the sheet. We choose graphene and a 2D metallic sheet as illustrative examples. This approach turns out to be very useful when treating graphene or graphene like sheets in non-planar structures

Bo E. Sernelius

2012-09-19

90

Six early cores of the MASURCA R-Z program were modeled using ERANOS 2.1. These cores were designed such that their neutron spectra would be similar to that of an oxide-fueled sodium-cooled fast reactor, some containing enriched uranium and others containing depleted uranium and plutonium. Effects of modeling assumptions and solution methods both in ECCO lattice calculations and in BISTRO Sn flux solutions were evaluated using JEFF-3.1 cross-section libraries. Reactivity effects of differences between JEFF-3.1 and ENDF/B-VI.8 were also quantified using perturbation theory analysis. The most important nuclide with respect to reactivity differences between cross-section libraries was 23Na, primarily a result of differences in the angular dependence of elastic scattering which is more forward-peaked in ENDF/B-VI.8 than in JEFF-3.1. Differences in 23Na inelastic scattering cross-sections between libraries also generated significant differences in reactivity, more due to the differences in magnitude of the cross-sections than the angular dependence. The nuclide 238U was also found to be important with regard to reactivity differences between the two libraries mostly due to a large effect of inelastic scattering differences and two smaller effects of elastic scattering and fission cross-sections. In the cores which contained plutonium, 239Pu fission cross-section differences contributed significantly to the reactivity differences between libraries.

MIchael A. Pope

2010-02-01

91

NSDL National Science Digital Library

The RandomWalk2D program simulates a random walk in two dimensions. The default number of walkers is 1000, and the probability of going right, left up or down at any step is the same. RandomWalk2D is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double clicking the stp RandomWalk2D.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2008-10-10

92

2D microwave imaging reflectometer electronics.

A 2D microwave imaging reflectometer system has been developed to visualize electron density fluctuations on the DIII-D tokamak. Simultaneously illuminated at four probe frequencies, large aperture optics image reflections from four density-dependent cutoff surfaces in the plasma over an extended region of the DIII-D plasma. Localized density fluctuations in the vicinity of the plasma cutoff surfaces modulate the plasma reflections, yielding a 2D image of electron density fluctuations. Details are presented of the receiver down conversion electronics that generate the in-phase (I) and quadrature (Q) reflectometer signals from which 2D density fluctuation data are obtained. Also presented are details on the control system and backplane used to manage the electronics as well as an introduction to the computer based control program. PMID:25430247

Spear, A G; Domier, C W; Hu, X; Muscatello, C M; Ren, X; Tobias, B J; Luhmann, N C

2014-11-01

93

Modelling RF sources using 2-D PIC codes

In recent years, many types of RF sources have been successfully modelled using 2-D PIC codes. Both cross field devices (magnetrons, cross field amplifiers, etc.) and pencil beam devices (klystrons, gyrotrons, TWT'S, lasertrons, etc.) have been simulated. All these devices involve the interaction of an electron beam with an RF circuit. For many applications, the RF structure may be approximated by an equivalent circuit, which appears in the simulation as a boundary condition on the electric field ( port approximation''). The drive term for the circuit is calculated from the energy transfer between beam and field in the drift space. For some applications it may be necessary to model the actual geometry of the structure, although this is more expensive. One problem not entirely solved is how to accurately model in 2-D the coupling to an external waveguide. Frequently this is approximated by a radial transmission line, but this sometimes yields incorrect results. We also discuss issues in modelling the cathode and injecting the beam into the PIC simulation.

Eppley, K.R.

1993-03-01

94

Modelling RF sources using 2-D PIC codes

In recent years, many types of RF sources have been successfully modelled using 2-D PIC codes. Both cross field devices (magnetrons, cross field amplifiers, etc.) and pencil beam devices (klystrons, gyrotrons, TWT`S, lasertrons, etc.) have been simulated. All these devices involve the interaction of an electron beam with an RF circuit. For many applications, the RF structure may be approximated by an equivalent circuit, which appears in the simulation as a boundary condition on the electric field (``port approximation``). The drive term for the circuit is calculated from the energy transfer between beam and field in the drift space. For some applications it may be necessary to model the actual geometry of the structure, although this is more expensive. One problem not entirely solved is how to accurately model in 2-D the coupling to an external waveguide. Frequently this is approximated by a radial transmission line, but this sometimes yields incorrect results. We also discuss issues in modelling the cathode and injecting the beam into the PIC simulation.

Eppley, K.R.

1993-03-01

95

TWOTRAN2 solves the two-dimensional multigroup transport equation in (x,y), (r,theta), and (r,z) geometries. Both regular and adjoint, inhomogeneous and homogeneous (keff and eigenvalue searches) problems subject to vacuum, reflective, periodic, white or input-specified boundary flux conditions are solved. General anisotropic scattering is allowed and anisotropic inhomogeneous sources are permitted.CDC7600,6600;IBM360\\/195; FORTRAN IV; Five output units, five interface units (use of interface

K. D. Lathrop; F. W. Brinkley

2008-01-01

96

Radio detection of interstellar N2D/+/

NASA Technical Reports Server (NTRS)

Line emission from the J = 1-0 transition of interstellar N2D(+) has been detected toward the cool dust cloud L134 N. The N2H(+)/N2D(+) total-projected-density ratio in this cloud is estimated to be about 2.22. Upper limits are obtained for the fractional ionization as well as the CO and N2 abundances in L134 N. The results are shown to support the previously discovered enhancement of the abundance of deuterated molecules in cool dust clouds.

Snyder, L. E.; Watson, W. D.; Hollis, J. M.; Buhl, D.

1977-01-01

97

Lennard-Jones 2D Metropolis Model

NSDL National Science Digital Library

The Lennard-Jones 2D Metropolis Model is a Monte Carlo simulation of Lennard-Jones particles in two dimensions in contact with a heat bath. The default initial condition is a rectangular configuration of N=64 particles in a box of length L = 18 and a temperature T= 1. The Lennard-Jones 2D Metropolis Model was developed using the Easy Java/JavaScript Simulations (EjsS) version 5 modeling tool. It is distributed as a ready-to-run (compiled) Java archive.

Christian, Wolfgang

2014-07-27

98

Harmonic generation in 2D layered materials

NASA Astrophysics Data System (ADS)

Two-Dimensional (2D) layered materials have garnered interest due to their novel optical and electronic properties. In this work, we investigate Second Harmonic Generation (SHG) in Tungsten Disulfide (WS2) monolayers grown on SiO2/Si substrates and suspended on a transmission electron microscopy grid; we find an unusually large second order susceptibility, which is nearly three orders of magnitude larger than common nonlinear crystals. We have also developed a Green's function based formalism to model the harmonic generation from a 2D layer .

Janisch, Corey; Ma, Ding; Mehta, Nikhil; Laura-Elias, Ana; Perea-Lopez, Nestor; Terrones, Mauricio; Liu, Zhiwen

2014-09-01

99

Inkjet printing of 2D layered materials.

Inkjet printing of 2D layered materials, such as graphene and MoS2, has attracted great interests for emerging electronics. However, incompatible rheology, low concentration, severe aggregation and toxicity of solvents constitute critical challenges which hamper the manufacturing efficiency and product quality. Here, we introduce a simple and general technology concept (distillation-assisted solvent exchange) to efficiently overcome these challenges. By implementing the concept, we have demonstrated excellent jetting performance, ideal printing patterns and a variety of promising applications for inkjet printing of 2D layered materials. PMID:25169938

Li, Jiantong; Lemme, Max C; Östling, Mikael

2014-11-10

100

property of the guide: that is, they require arg(Z (%)) = arg(p (%)) #12; arg(p (%,0)) =0 + + arg(p (%,z and the conjugate of the current [3]. The causal circuit theory of [1] imposes the same power normalization, so arg(Z ) = arg(p ). In addition,0 + #12; ln Z0(%) arg[p(%)], Z0(%) e (arg[p(%)]) , [[f(%)

Perkins, Richard A.

101

Through algebraic geometry we became familiar with the correspondence between geometrical spaces and commutative algebra.\\u000a The aim of this talk is to show an analogous correspondence, in the domain of real analysis, between geometrical spaces and\\u000a algebras of functional analysis, going beyond the commutative case. This theory is based on three essential points:\\u000a \\u000a \\u000a 1. \\u000a \\u000a The existence of many examples of

Alain Connes

1994-01-01

102

NSDL National Science Digital Library

This is one of the best online resources about fractals, and is "meant to support a first course in fractal geometry for students without especially strong mathematical preparation." The site is incredibly deep, providing everything from the most basic definitions and non-technical discussions to involved mathematical formulations. Interactive Java applets, downloadable software for the PC and Macintosh, and laboratory activities are also presented. A particularly interesting section of the site explores about 100 places in nature and society where fractals are found.

Frame, Michael; Mandelbrot, Benoit; Neger, Nial

103

We describe the geometry of foams squeezed between two solid plates (2D GG foams) in two main asymptotic regimes: fully dry floor tiles and dry pancakes. We predict an abrupt transition between both regimes, with a substantial change in the Plateau border radius. This should be observable in different types of experiments on such 2D GG foams: when foam is being progressively dried or wetted, when it is being squeezed further or stretched, when it coarsens through film breakage or Oswald ripening.

Pierre Rognon; François Molino; Cyprien Gay

2009-02-13

104

2-1/2-D electromagnetic modeling of nodular defects in high-power multilayer optical coatings

Advances in the design and production of high damage threshold optical coatings for use in mirrors and polarizers have been driven by the design requirements of high-power laser systems such as the proposed 1.8-MJ National Ignition Facility (NIF) and the prototype 12- kJ Beamlet laser system. The present design of the NIF will include 192 polarizers and more than 1100 mirrors. Currently, the material system of choice for high-power multilayer optical coatings with high damage threshold applications near 1.06 {mu}m are e-beam deposited HfO{sub 2}/Si0{sub 2} coatings. However, the optical performance and laser damage thresholds of these coatings are limited by micron-scale defects and insufficient control over layer thickness. In this report, we will discuss the results of our 2-1/2-D finite-element time- domain (FDTD) EM modeling effort for rotationally-symmetric nodular defects in multilayer dielectric HR coatings. We have added a new diagnostic to the 2-1/2-D FDTD EM code, AMOS, that enables us to calculate the peak steady-state electric fields throughout a 2-D planar region containing a 2-D r-z cross-section of the axisymmetric nodular defect and surrounding multilayer dielectric stack. We have also generated a series of design curves to identify the range of loss tangents for Si0{sub 2} and HfO{sub 2} consistent with the experimentally determined power loss of the HR coatings. In addition, we have developed several methods to provide coupling between the EM results and the thermal-mechanical simulation effort.

Molau, N.E.; Brand, H.R.; Kozlowski, M.R.; Shang, C.C.

1996-07-01

105

It has been proposed that quantum mechanics and string theory share a common inner syntax, the relational logic of C. S. Peirce. Along this line of thought we consider the relations represented by spinors. Spinor composition leads to the emergence of Minkowski spacetime. Inversely the Minkowski spacetime is istantiated by the Weyl spinors, while the merge of two Weyl spinors gives rise to a Dirac spinor. Our analysis is applied also to the string geometry. The string constraints are represented by real spinors, which create a parametrization of the string worldsheet identical to the Enneper-Weierstass representation of minimal surfaces. Further, a spinorial study of the AdS3 spacetime reveals a Hopf fibration AdS3 \\rightarrow AdS2. The conformal symmetry inherent in AdS3 is pointed out. Our work indicates the hidden ties between logic-quantum mechanics-string theory-geometry and vindicates the Wheeler's proposal of pregeometry as a large network of logical propositions.

A. Nicolaidis; V. Kiosses

2012-01-03

106

I. INTRODUCTION 2-D Spatial Smoothing for

I. INTRODUCTION 2-D Spatial Smoothing for Multipath Coherent Signal Separation HONGYI WANG Lucent direction of arrival (DOA) estimation of coherent or highly correlated signals. The optimal weighted subspace fitting (WSF) DOA estimation [2] algorithm has been previously proposed to identify the coherent

Liu, K. J. Ray

107

Animation : 2D versus 3D and their combined effect

This thesis studies the differences in the perception of space and character movement between 2D and 3D animation. 2D animation is defined by elements constructed in a 2D environment while 3D animation by elements constructed ...

Au, Kristin C

2014-01-01

108

The Geometry of 2 Ã? 2 Matrices William M. Goldman Algebraicizing geometry Euclidean geometry Spherical geometry Triangle tilings Stereographic projection Hyperbolic Geometry Matrices as geometric objects Conclusion The Geometry of 2 Ã? 2 Matrices William M. Goldman Department of Mathematics, University

Goldman, William

109

Geometrical Correlation and Matching of 2d Image Shapes

NASA Astrophysics Data System (ADS)

The problem of image correspondence measure selection for image comparison and matching is addressed. Many practical applications require image matching "just by shape" with no dependence on the concrete intensity or color values. Most popular technique for image shape comparison utilizes the mutual information measure based on probabilistic reasoning and information theory background. Another approach was proposed by Pytiev (so called "Pytiev morphology") based on geometrical and algebraic reasoning. In this framework images are considered as piecewise-constant 2D functions, tessellation of image frame by the set of non-intersected connected regions determines the "shape" of image and the projection of image onto the shape of other image is determined. Morphological image comparison is performed using the normalized morphological correlation coefficients. These coefficients estimate the closeness of one image to the shape of other image. Such image analysis technique can be characterized as an ""ntensity-to-geometry" matching. This paper generalizes the Pytiev morphological approach for obtaining the pure "geometry-to-geometry" matching techniques. The generalized intensity-geometrical correlation coefficient is proposed including the linear correlation coefficient and the square of Pytiev correlation coefficient as its partial cases. The morphological shape correlation coefficient is proposed based on the statistical averaging of images with the same shape. Centered morphological correlation coefficient is obtained under the condition of intensity centering of averaged images. Two types of symmetric geometrical normalized correlation coefficients are proposed for comparison of shape-tessellations. The technique for correlation and matching of shapes with ordered intensities is proposed with correlation measures invariant to monotonous intensity transformations. The quality of proposed geometrical correlation measures is experimentally estimated in the task of visual (TV) and infrared (IR) image matching. First experimental results demonstrate competitive quality and better computational performance relative to state-of-art mutual information measure.

Vizilter, Y. V.; Zheltov, S. Y.

2012-07-01

110

Bandgaps and directional propagation of elastic waves in 2D square zigzag lattice structures

NASA Astrophysics Data System (ADS)

In this paper we propose various types of two-dimensional (2D) square zigzag lattice structures, and we study their bandgaps and directional propagation of elastic waves. The band structures and the transmission spectra of the systems are calculated by using the finite element method. The effects of the geometry parameters of the 2D-zigzag lattices on the bandgaps are investigated and discussed. The mechanism of the bandgap generation is analyzed by studying the vibration modes at the bandgap edges. Multiple wide complete bandgaps are found in a wide porosity range owing to the separation of the degeneracy by introducing bending arms. The bandgaps are sensitive to the geometry parameters of the systems. The deformed displacement fields of the transient response of finite structures subjected to time-harmonic loads are presented to show the directional wave propagation. The research in this paper is relevant to the practical design of cellular structures with enhanced vibro-acoustics performance.

Wang, Yan-Feng; Wang, Yue-Sheng; Zhang, Chuanzeng

2014-12-01

111

Spin polarization effect in 2D and Q2D electron gas

NASA Astrophysics Data System (ADS)

We use the constructed spin-dependent static local field functions to calculate the plasmon dispersion of two dimensional spin polarized electron gas (2D SPEG) over a range of electron densities at arbitrarily spin polarization. We also investigate how the finite width of electron layer will affect the plasmon frequency and inverse static dielectric function of 2D SPEG. Our results show that the effect of finite thickness on plasmon dispersion and inverse dielectric function becomes considerable even at high densities in 2D SPEG.

Kanjouri, F.; Esmailian, A. H.; Molayem, M.

2011-02-01

112

The timelike half-supersymmetric backgrounds of N=2, D=4 supergravity with Fayet-Iliopoulos gauging

Subject to some relatively mild assumptions, we derive the complete form of all timelike half-supersymmetric solutions to N=2, D=4 gauged supergravity coupled to an arbitrary number of Abelian vector multiplets. This is done using spinorial geometry techniques. Explicit examples are given for a simple prepotential. Among the solutions, there are near-horizon geometries of extremal rotating supersymmetric black holes still to be discovered, with a nontrivial dependence of the scalar fields on one of the horizon coordinates.

Klemm, Dietmar; Zorzan, Emanuele [Dipartimento di Fisica, Universita di Milano, Via Celoria 16, I-20133 Milano (Italy) and INFN, Sezione di Milano, Via Celoria 16, I-20133 Milano (Italy)

2010-08-15

113

ERAST Demonstrator 2 (D-2) in flight

NASA Technical Reports Server (NTRS)

ERAST Demonstrator 2 (D-2) in flight during 1996. The Demonstrator 2 (D-2) was built by Scaled Composites of Mojave, California, to test remote flight-control capabilities. As a result, it had only limited provisions for a scientific payload. The D-2 was also unusual in that it could be flown by either a pilot in an open cockpit or by remote control. It was powered by a 100-horsepower Rotax 914 piston engine turning a three-bladed propeller. It late 1996, it was flown to test the vehicle's ability to communicate over the horizon using a Tracking and Data Relay Satellite. The D-2 resumed flights in August 1998 to test a triply-redundant flight control system that would allow remotely piloted high-altitude missions.

1996-01-01

114

Compact 2-D graphical representation of DNA

NASA Astrophysics Data System (ADS)

We present a novel 2-D graphical representation for DNA sequences which has an important advantage over the existing graphical representations of DNA in being very compact. It is based on: (1) use of binary labels for the four nucleic acid bases, and (2) use of the 'worm' curve as template on which binary codes are placed. The approach is illustrated on DNA sequences of the first exon of human ?-globin and gorilla ?-globin.

Randi?, Milan; Vra?ko, Marjan; Zupan, Jure; Novi?, Marjana

2003-05-01

115

Interrogating Fiber Formation Kinetics with Automated 2D-IR Spectroscopy

NASA Astrophysics Data System (ADS)

A new method for collecting 2D-IR spectra that utilizes both a pump-probe beam geometry and a mid-IR pulse shaper is used to gain a fuller understanding of fiber formation in the human islet amyloid polypeptide (hIAPP). We extract structural kinetics in order to better understand aggregation in hIAPP, the protein component of the amyloid fibers found to inhibit insulin production in type II diabetes patients.

Strasfeld, David B.; Ling, Yun L.; Shim, Sang-Hee; Zanni, Martin T.

116

A simple method for quantitative imaging of 2D acoustic fields using refracto-vibrometry

NASA Astrophysics Data System (ADS)

This paper presents a simple 2D method for rapid time resolved quantitative imaging of acoustic waves using refracto-vibrometry. We present the theoretical background, the experimental method and reconstructions of acoustic reflection and interference. We investigate the applicability of the method, in particular the effect of sound radiator geometry. Finite element and experimental reconstructions of the sound fields are analysed. The spatial limitations and accuracy of the method are presented and discussed.

Malkin, Robert; Todd, Thomas; Robert, Daniel

2014-09-01

117

Toward an Efficient Icing CFD Process Using an Interactive Software Toolkit--SmaggIce 2D

Two-dimensional CFD analysis for iced airfoils can be a labor-intensive task. The software toolkit SmaggIce 2D is being developed to help streamline the CFD process and provide the unique features needed for icing. When complete, it will include a combination of partially automated and fully interactive tools for all aspects of the tasks leading up to the flow analysis: geometry

Mary B. Vickerman; Yung K. Choo; Herbert W. Schilling; Marivell Baez; Donald C. Braun; Barbara J. Cotton

2002-01-01

118

Patient-specific bronchoscope simulation with pq -space-based 2D\\/3D registration†

Objective: The use of patient-specific models for surgical simulation requires photorealistic rendering of 3D structure and surface properties. For bronchoscope simulation, this requires augmenting virtual bronchoscope views generated from 3D tomographic data with patient-specific bronchoscope videos. To facilitate matching of video images to the geometry extracted from 3D tomographic data, this paper presents a new pq-space-based 2D\\/3D registration method for

Fani Deligianni; Adrian Chung; Guang-zhong Yang

2004-01-01

119

Estimation of 2-D Direction of Arrival with an Extended Correlation Matrix

This paper presents a new subspace-based 2D direction of arrival (DOA) estimation algorithm for narrowband sources with high-resolution localization capabilities. DOA estimation is achieved by using the noise-subspace eigenvectors of a new extended correlation matrix (ECM). A 2-L shape antenna array is proposed. Unlike common planar and circular arrays, the novel antenna array with this special geometry requires no pair

Ferid Harabi; Hatem Changuel; Ali Gharsallah

2007-01-01

120

Fluctuating Pressure Data from 2-D Nozzle Cold Flow Tests (Dual Bell)

NASA Technical Reports Server (NTRS)

Rocket engines nozzle performance changes as a vehicle climbs through the atmosphere. An altitude compensating nozzle, ACN, is intended to improve on a fixed geometry bell nozzle that performs at optimum at only one trajectory point. In addition to nozzle performance, nozzle transient loads are an important consideration. Any nozzle experiences large transient toads when shocks pass through the nozzle at start and shutdown. Additional transient toads will occur at transitional flow conditions. The objectives of cold flow nozzle testing at MSFC are CFD benchmark / calibration and Unsteady flow / sideloads. Initial testing performed with 2-D inserts to 14" transonic wind tunnel. Recent review of 2-D data in preparation for nozzle test facility 3-D testing. This presentation shows fluctuating pressure data and some observations from 2-D dual-bell nozzle cold flow tests.

Nesman, Tomas E.

2001-01-01

121

MAGNUM-2D computer code: user's guide

Information relevant to the general use of the MAGNUM-2D computer code is presented. This computer code was developed for the purpose of modeling (i.e., simulating) the thermal and hydraulic conditions in the vicinity of a waste package emplaced in a deep geologic repository. The MAGNUM-2D computer computes (1) the temperature field surrounding the waste package as a function of the heat generation rate of the nuclear waste and thermal properties of the basalt and (2) the hydraulic head distribution and associated groundwater flow fields as a function of the temperature gradients and hydraulic properties of the basalt. MAGNUM-2D is a two-dimensional numerical model for transient or steady-state analysis of coupled heat transfer and groundwater flow in a fractured porous medium. The governing equations consist of a set of coupled, quasi-linear partial differential equations that are solved using a Galerkin finite-element technique. A Newton-Raphson algorithm is embedded in the Galerkin functional to formulate the problem in terms of the incremental changes in the dependent variables. Both triangular and quadrilateral finite elements are used to represent the continuum portions of the spatial domain. Line elements may be used to represent discrete conduits. 18 refs., 4 figs., 1 tab.

England, R.L.; Kline, N.W.; Ekblad, K.J.; Baca, R.G.

1985-01-01

122

Engineering Light Outcoupling in 2D Materials.

When light is incident on 2D transition metal dichalcogenides (TMDCs), it engages in multiple reflections within underlying substrates, producing interferences that lead to enhancement or attenuation of the incoming and outgoing strength of light. Here, we report a simple method to engineer the light outcoupling in semiconducting TMDCs by modulating their dielectric surroundings. We show that by modulating the thicknesses of underlying substrates and capping layers, the interference caused by substrate can significantly enhance the light absorption and emission of WSe2, resulting in a ?11 times increase in Raman signal and a ?30 times increase in the photoluminescence (PL) intensity of WSe2. On the basis of the interference model, we also propose a strategy to control the photonic and optoelectronic properties of thin-layer WSe2. This work demonstrates the utilization of outcoupling engineering in 2D materials and offers a new route toward the realization of novel optoelectronic devices, such as 2D LEDs and solar cells. PMID:25602462

Lien, Der-Hsien; Kang, Jeong Seuk; Amani, Matin; Chen, Kevin; Tosun, Mahmut; Wang, Hsin-Ping; Roy, Tania; Eggleston, Michael S; Wu, Ming C; Dubey, Madan; Lee, Si-Chen; He, Jr-Hau; Javey, Ali

2015-02-11

123

2D Prony-Huang transform: a new tool for 2D spectral analysis.

This paper provides an extension of the 1D Hilbert Huang transform for the analysis of images using recent optimization techniques. The proposed method consists of: 1) adaptively decomposing an image into oscillating parts called intrinsic mode functions (IMFs) using a mode decomposition procedure and 2) providing a local spectral analysis of the obtained IMFs in order to get the local amplitudes, frequencies, and orientations. For the decomposition step, we propose two robust 2D mode decompositions based on nonsmooth convex optimization: 1) a genuine 2D approach, which constrains the local extrema of the IMFs and 2) a pseudo-2D approach, which separately constrains the extrema of lines, columns, and diagonals. The spectral analysis step is an optimization strategy based on Prony annihilation property and applied on small square patches of the IMFs. The resulting 2D Prony–Huang transform is validated on simulated and real data. PMID:25330485

Schmitt, Jérémy; Pustelnik, Nelly; Borgnat, Pierre; Flandrin, Patrick; Condat, Laurent

2014-12-01

124

Projective Geometry and Pappus' Theorem Kelly McKinnie History Pappus' Theorem Geometries Picturing the projective plane Lines in projective geometry Back to Pappus' Theorem Proof of Pappus' Theorem Projective Geometry and Pappus' Theorem Kelly McKinnie March 23, 2010 #12;Projective Geometry and Pappus' Theorem

Gideon, Rudy A.

125

Flow Structures over Fixed 2D Bedforms in Transient States

NASA Astrophysics Data System (ADS)

Flow processes measured in the laboratory over fixed, 2D or 3D bedforms have mostly been conducted at singular flow depths and with bedform dimensions set by scaling laws based upon equilibrium flow conditions. These results thus have limited applicability to many natural situations where bedforms and flow fields are co-evolving at different rates in response to transient conditions, such as changes in flow depth and flow discharge associated with a flood. The research presented herein investigates flow processes over 2D fixed bedforms under a range of non-equilibrium, transient, states in order to quantify the spatio-temporal changes in turbulence associated with steady conditions that are set at non-equilibrium depths and velocities. Flow field information was obtained via Particle Imaging Velocimetry for a range of flow depths and mean flow velocities, mimicking conditions during the transient evolution of flow fields and bedforms during a flood wave. Changes in either flow depth or mean flow speed causes substantial migrations in the locations of maximum turbulence generation and dissipation. Flow speed does not have a significant impact on the height or length of the separation zone shear layer despite a large range in depth-averaged mean velocity whilst there is a weak relationship between decreasing flow depth and a reduction in flow separation zone length. The flow field downstream of reattachment changes substantially with changes in mean flow speed and flow depth. The turbulent wake zone after flow reattachment extends further downstream over the stoss slope and moves closer towards the bed with increasing mean flow speed. Wake stacking from upstream dunes over the flow separation zone was observed without a change in bedform geometry. These changes will likely drive morphological adjustment on the dune stoss side in response to flow variability and thus permits an exploration of the links between sediment transport, morphodynamics, and transient flow field dynamics of fluvial dunes.

Unsworth, C. A.; Parsons, D. R.; Reesink, A.; Best, J.; Ashworth, P. J.; Hardy, R. J.

2013-12-01

126

WFR-2D: an analytical model for PWAS-generated 2D ultrasonic guided wave propagation

NASA Astrophysics Data System (ADS)

This paper presents WaveFormRevealer 2-D (WFR-2D), an analytical predictive tool for the simulation of 2-D ultrasonic guided wave propagation and interaction with damage. The design of structural health monitoring (SHM) systems and self-aware smart structures requires the exploration of a wide range of parameters to achieve best detection and quantification of certain types of damage. Such need for parameter exploration on sensor dimension, location, guided wave characteristics (mode type, frequency, wavelength, etc.) can be best satisfied with analytical models which are fast and efficient. The analytical model was constructed based on the exact 2-D Lamb wave solution using Bessel and Hankel functions. Damage effects were inserted in the model by considering the damage as a secondary wave source with complex-valued directivity scattering coefficients containing both amplitude and phase information from wave-damage interaction. The analytical procedure was coded with MATLAB, and a predictive simulation tool called WaveFormRevealer 2-D was developed. The wave-damage interaction coefficients (WDICs) were extracted from harmonic analysis of local finite element model (FEM) with artificial non-reflective boundaries (NRB). The WFR-2D analytical simulation results were compared and verified with full scale multiphysics finite element models and experiments with scanning laser vibrometer. First, Lamb wave propagation in a pristine aluminum plate was simulated with WFR-2D, compared with finite element results, and verified by experiments. Then, an inhomogeneity was machined into the plate to represent damage. Analytical modeling was carried out, and verified by finite element simulation and experiments. This paper finishes with conclusions and suggestions for future work.

Shen, Yanfeng; Giurgiutiu, Victor

2014-03-01

127

Another solution of 2D Ising model

The partition function of the Ising model on a two-dimensional regular lattice is calculated by using the matrix representation of a Clifford algebra (the Dirac algebra), with number of generators equal to the number of lattice sites. It is shown that the partition function over all loops in a 2D lattice including self-intersecting ones is the trace of a polynomial in terms of Dirac matrices. The polynomial is an element of the rotation group in the spinor representation. Thus, the partition function is a function of a character on an orthogonal group of a high degree in the spinor representation.

Vergeles, S. N. [Russian Academy of Sciences, Landau Institute for Theoretical Physics (Russian Federation)], E-mail: vergeles@itp.ac.ru

2009-04-15

128

Point Charge Forces in 2D Model

NSDL National Science Digital Library

The Point Charge Forces in Two-Dimensions model investigates the electric force that a charged particle experiences in a two-dimensional situation, because of four other nearby charged particles. The net electric force is shown as an arrow attached to the particle. Note that each particle can be dragged around the screen. The Point Charge Forces in Two-Dimensions was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_bu_Point_Charge_Force_2D.jar file will run the program if Java is installed.

Duffy, Andrew

2010-04-16

129

2-D or not 2-D, that is the question: A Northern California test

Reliable estimates of the seismic source spectrum are necessary for accurate magnitude, yield, and energy estimation. In particular, how seismic radiated energy scales with increasing earthquake size has been the focus of recent debate within the community and has direct implications on earthquake source physics studies as well as hazard mitigation. The 1-D coda methodology of Mayeda et al. has provided the lowest variance estimate of the source spectrum when compared against traditional approaches that use direct S-waves, thus making it ideal for networks that have sparse station distribution. The 1-D coda methodology has been mostly confined to regions of approximately uniform complexity. For larger, more geophysically complicated regions, 2-D path corrections may be required. The complicated tectonics of the northern California region coupled with high quality broadband seismic data provides for an ideal ''apples-to-apples'' test of 1-D and 2-D path assumptions on direct waves and their coda. Using the same station and event distribution, we compared 1-D and 2-D path corrections and observed the following results: (1) 1-D coda results reduced the amplitude variance relative to direct S-waves by roughly a factor of 8 (800%); (2) Applying a 2-D correction to the coda resulted in up to 40% variance reduction from the 1-D coda results; (3) 2-D direct S-wave results, though better than 1-D direct waves, were significantly worse than the 1-D coda. We found that coda-based moment-rate source spectra derived from the 2-D approach were essentially identical to those from the 1-D approach for frequencies less than {approx}0.7-Hz, however for the high frequencies (0.7{le} f {le} 8.0-Hz), the 2-D approach resulted in inter-station scatter that was generally 10-30% smaller. For complex regions where data are plentiful, a 2-D approach can significantly improve upon the simple 1-D assumption. In regions where only 1-D coda correction is available it is still preferable over 2-D direct wave-based measures.

Mayeda, K; Malagnini, L; Phillips, W S; Walter, W R; Dreger, D

2005-06-06

130

A 2D driven 3D vessel segmentation algorithm for 3D digital subtraction angiography data

NASA Astrophysics Data System (ADS)

Cerebrovascular disease is among the leading causes of death in western industrial nations. 3D rotational angiography delivers indispensable information on vessel morphology and pathology. Physicians make use of this to analyze vessel geometry in detail, i.e. vessel diameters, location and size of aneurysms, to come up with a clinical decision. 3D segmentation is a crucial step in this pipeline. Although a lot of different methods are available nowadays, all of them lack a method to validate the results for the individual patient. Therefore, we propose a novel 2D digital subtraction angiography (DSA)-driven 3D vessel segmentation and validation framework. 2D DSA projections are clinically considered as gold standard when it comes to measurements of vessel diameter or the neck size of aneurysms. An ellipsoid vessel model is applied to deliver the initial 3D segmentation. To assess the accuracy of the 3D vessel segmentation, its forward projections are iteratively overlaid with the corresponding 2D DSA projections. Local vessel discrepancies are modeled by a global 2D/3D optimization function to adjust the 3D vessel segmentation toward the 2D vessel contours. Our framework has been evaluated on phantom data as well as on ten patient datasets. Three 2D DSA projections from varying viewing angles have been used for each dataset. The novel 2D driven 3D vessel segmentation approach shows superior results against state-of-the-art segmentations like region growing, i.e. an improvement of 7.2% points in precision and 5.8% points for the Dice coefficient. This method opens up future clinical applications requiring the greatest vessel accuracy, e.g. computational fluid dynamic modeling.

Spiegel, M.; Redel, T.; Struffert, T.; Hornegger, J.; Doerfler, A.

2011-10-01

131

Intermittency in 2D soap film turbulence

NASA Astrophysics Data System (ADS)

The Reynolds number dependency of intermittency for 2D turbulence is studied in a flowing soap film. The Reynolds number used here is the Taylor microscale Reynolds number R?, which ranges from 20 to 800. Strong intermittency is found for both the inverse energy and direct enstrophy cascades as measured by (a) the pdf of velocity differences P(?u(r)) at inertial scales r, (b) the kurtosis of P(?xu), and (c) the scaling of the so-called intermittency exponent ?, which is zero if intermittency is absent. Measures (b) and (c) are quantitative, while (a) is qualitative. These measurements are in disagreement with some previous results but not all. The velocity derivatives are nongaussian at all R? but show signs of becoming gaussian as R? increases beyond the largest values that could be reached. The kurtosis of P(?u(r)) at various r indicates that the intermittency is scale dependent. The structure function scaling exponents also deviate strongly from the Kraichnan prediction. For the enstrophy cascade, the intermittency decreases as a power law in R?. This study suggests the need for a new look at the statistics of 2D turbulence.

Cerbus, R. T.; Goldburg, W. I.

2013-10-01

132

NSDL National Science Digital Library

The Lennard-Jones Fluid 2D program shows a system of particles in two dimensions interacting via the Lennard-Jones potential. The program displays the particles in the box as a function of time once the partition dividing the box into three parts are removed. The program is distributed as a ready-to-run (compiled) Java archive. Double-clicking the ejs_stp_LJFluid2D.jar file will run the program if Java is installed on your computer. The program was created using Ejs (Easy Java Simulations). You can modify this program and see how it is designed if you have Ejs installed by right-clicking within the window and selecting Open Ejs Model from the pop-up menu. Ejs, a part of the Open Source Physics Project, is designed to make it easier to access, modify, and generate computer models. Information about Ejs is available at www.um.es/fem/Ejs/. Additional Open Source Physics programs for Statistical and Thermal Physics can be found by searching ComPADRE for Open Source Physics, STP or Statistical and Thermal Physics.

Christian, Wolfgang; Cox, Anne; Gould, Harvey; Tobochnik, Jan

2008-06-03

133

NSDL National Science Digital Library

The Lennard-Jones 2D Demon Model is a Monte Carlo simulation of Lennard-Jones particles in two dimensions interacting with a Monte Carlo demon. A Monte Carlo demon is an extra degree of freedom that is allowed to transfer energy as it attempts to change the state of the system. The demon keeps track of its own energy and can take or give energy to a particle as it interacts with a randomly chosen particle. Because the demon cannot have negative energy, the total energy of the system remains constant -- as it should in the microcanonical ensemble. The demon is, in effect, a thermometer. Its extra degree of freedom perturbs the system very little and the average demon energy is proportional to the temperature of the system. (See Statistical and Thermal Physics notes by H. Gould and J. Tobochnik.) The Lennard-Jones 2D Demon Model was developed using the Easy Java/JavaScript Simulations (EjsS) version 5 modeling tool. It is distributed as a ready-to-run (compiled) Java archive.

Christian, Wolfgang

2014-08-01

134

Christian Bar Differential Geometry

.5 Trigonometry in spaces of constant curvature . . . . . . . . . . . . . . . . 133 5 Riemannian Geometry 143 5 apply differential geometry to derive the laws of trigonometry on spaces of constant curvature. One

Baer, Christian

135

2D-fractal based algorithms for nanoparticles characterization

NASA Astrophysics Data System (ADS)

Fractal geometry concerns the study of non-Euclidean geometrical figures generated by a recursive sequence of mathematical operations. The proposed 2D-fractal approach was applied to characterise the image structure and texture generated by fine and ultra-fine particles when impacting on a flat surface. The work was developed with reference to particles usually produced by ultra-fine milling addressed to generate nano-particles population. In order to generate different particle populations to utilize in the study, specific milling actions have been thus performed adopting different milling actions and utilising different materials, both in terms of original size class distribution and chemical-physical attributes. The aim of the work was to develop a simple, reliable and low cost analytical set of procedures with the ability to establish correlations between particles detected by fractal characteristics and their milled-induced-properties (i.e. size class distribution, shape, surface properties, etc.). Such logic should constitute the core of a control engine addressed to realize a full monitoring of the milling process as well as to establish correlation between operative parameters, fed and resulting products characteristics.

Bonifazi, Giuseppe; Serranti, Silvia

2014-02-01

136

Defect formation and coarsening in hexagonal 2D curved crystals.

In this work we study the processes of defect formation and coarsening of two-dimensional (2D) curved crystal structures. These processes are found to strongly deviate from their counterparts in flat systems. In curved backgrounds the process of defect formation is deeply affected by the curvature, and at the onset of a phase transition the early density of defects becomes highly inhomogeneous. We observe that even a single growing crystal can produce varying densities of defects depending on its initial position and local orientation with regard to the substrate. This process is completely different from flat space, where grain boundaries are formed due to the impingement of different propagating crystals. Quenching the liquid into the crystal phase leads to the formation of a curved polycrystalline structure, characterized by complex arrays of defects. During annealing, mechanisms of geodesic curvature-driven grain boundary motion and defect annihilation lead to increasing crystalline order. Linear arrays of defects diffuse to regions of high curvature, where they are absorbed by disclinations. At the early stage of coarsening the density of dislocations is insensitive to the geometry while the population of isolated disclinations is deeply affected by curvature. The regions with high curvature act as traps for the diffusion of different structures of defects, including disclinations and domain walls. PMID:25491780

García, Nicolás A; Pezzutti, Aldo D; Register, Richard A; Vega, Daniel A; Gómez, Leopoldo R

2015-01-21

137

Linear line spectropolarimetry as a new window to measure 2D and 3D wind geometries

NASA Astrophysics Data System (ADS)

Various theories have been proposed to predict how mass loss depends on the stellar rotation rate, both in terms of its strength, as well as its latitudinal dependence, crucial for our understanding of angular momentum evolution. Here we discuss the tool of linear spectropolarimetry that can probe the difference between mass loss from the pole versus the equator. Our results involve several groups of O stars and Wolf-Rayet stars, involving Oe stars, Of?p stars, Onfp stars, as well as the best candidate gamma-ray burst progenitors identified to date.

Vink, Jorick S.

2015-01-01

138

The dynamics of rhythmical aiming in 2D task space: Relation between geometry and kinematics under

-law relating curvature and tangential velocity of the trajectory did not resist the increase in ID. Kinematic & Flash, 1995). Moreover, the law has been found to hold under isometric conditions (Massey, Lurito

Jirsa, Viktor

139

Fatigue Crack Propagation under Complex Loading in Arbitrary 2D Geometries

Abstract: A reliable and cost effective two-phase methodology is proposed and implemented in two pieces of software to predict fatigue crack propagation in generic two-dimensional structural components under complex loading. First, the fatigue crack path and its stress intensity factor are calculated in a specialized finite-element software, using small crack increments. At each crack propagation step, the mesh is automatically

Antonio C. O. Miranda; Marco A. Meggiolaro; Jaime T. P. Castro; Luiz F. Martha; Tulio N. Bittencourt

2001-01-01

140

Diode particle simulations in 2-D and 3-D geometries by using LSP and MCNP code

When test explosives are irradiated by flash X-ray, the dynamic properties can be analyzed by observing crack progress and fracture movement. Our radiographic device has a self-magnetic pinched(SMP) diode to generate flash X-ray. To optimize diode performance the SMP diode is simulated with the combination of LSP and MCNP code. The electron particle data are extracted at anode position of

S. H. Han; S. H. Beak; S. H. Hong; S. Y. Song; J. Lee

2011-01-01

141

RSensitivity of planar flows to forcing geometry

NASA Astrophysics Data System (ADS)

We present experiments which reveal fundamental aspects of planar flows in confined geometries. The work has application to 2D flows in this films, geophysical flows, and MHD. We examine the laminar regime of the flow studied by Boubnov, Dalziel & Linden (1994). A planar flow is produced by source-sink forcing in a stably stratified fluid contained in a tank of square horizontal section. The source-sink forcing consists of 4 or 8 pairs of pipes connected to a peristaltic pump: each pair sucks and re-enters fluid from the same density layer. The Reynolds number based on the measured velocity field is O(10^2). We find that the resulting flow patterns are extremely sensitive to the configurations of the source-sink pairs in relation to the geometry of the flow domain. For some configurations, steady flows develop which resemble the inviscid eigenmodes for a homogeneous (unforced) boundary condition assuming a linear relation between the stream function and the vorticity. A dominant single vortex pattern which was identified in the previous work as the result of inverse energy cascade of 2D turbulence turned out to be one of the eigenmodes. For other configurations, the flow patterns change irregularly which provides a new mechanism of 2D mixing. We will also present the effect of viscosity which relates these laminar flows to 2D turbulent flows and Stokes flows.

Kanda, Isao; Linden, Paul F.

1999-11-01

142

Full revivals in 2D quantum walks

NASA Astrophysics Data System (ADS)

Recurrence of a random walk is described by the Pólya number. For quantum walks, recurrence is understood as the return of the walker to the origin, rather than the full revival of its quantum state. Localization for two-dimensional quantum walks is known to exist in the sense of non-vanishing probability distribution in the asymptotic limit. We show, on the example of the 2D Grover walk, that one can exploit the effect of localization to construct stationary solutions. Moreover, we find full revivals of a quantum state with a period of two steps. We prove that there cannot be longer cycles for a four-state quantum walk. Stationary states and revivals result from interference, which has no counterpart in classical random walks.

Štefa?ák, M.; Kollár, B.; Kiss, T.; Jex, I.

2010-09-01

143

PROJECTIVE GEOMETRY KRISTIN DEAN

PROJECTIVE GEOMETRY KRISTIN DEAN Abstract. This paper investigates the nature of finite geometries. It will focus on the finite geometries known as projective planes and conclude with the example of the Fano plane. Contents 1. Basic Definitions 1 2. Axioms of Projective Geometry 2 3. Linear Algebra

May, J. Peter

144

ERIC Educational Resources Information Center

Geometry provides a natural window into what it is like to do mathematics. In the world of geometry, playful experimentation is often more fruitful than following a procedure, and logic plus a few axioms can open new worlds. Nonetheless, teaching a geometry course in a way that combines both rigor and play can be difficult. Many geometry courses…

Cukier, Mimi; Asdourian, Tony; Thakker, Anand

2012-01-01

145

Analytic Structures Geometry and Categoricity John T. Baldwin January 8, 2012 #12;Geometry and Categoricity Homogeneity Zariski Structures Analytic Structures Whig History #12;Geometry and Categoricity John T. Baldwin in (C, +, Â·) by `analytically' definable. Response #12;Geometry and Categoricity John T. Baldwin

Baldwin, John T.

146

2D Discrete Fourier Transform on Sliding Windows.

Discrete Fourier transform (DFT) is the most widely used method for determining the frequency spectra of digital signals. In this paper, a 2D sliding DFT (2D SDFT) algorithm is proposed for fast implementation of the DFT on 2D sliding windows. The proposed 2D SDFT algorithm directly computes the DFT bins of the current window using the precalculated bins of the previous window. Since the proposed algorithm is designed to accelerate the sliding transform process of a 2D input signal, it can be directly applied to computer vision and image processing applications. The theoretical analysis shows that the computational requirement of the proposed 2D SDFT algorithm is the lowest among existing 2D DFT algorithms. Moreover, the output of the 2D SDFT is mathematically equivalent to that of the traditional DFT at all pixel positions. PMID:25585421

Park, Chun-Su

2015-03-01

147

Monistic conception of geometry

One considers the monistic conception of a geometry, where there is only one fundamental quantity (world function). All other geometrical quantities a derivative quantities (functions of the world function). The monisitc conception of a geometry is compared with pluralistic conceptions of a geometry, where there are several independent fundamental geometrical quantities. A generalization of a pluralistic conception of the proper Euclidean geometry appears to be inconsistent, if the generalized geometry is inhomogeneous. In particular, the Riemannian geometry appears to be inconsistent, in general, if it is obtained as a generalization of the pluralistic conception of the Euclidean geometry.

Yuri A. Rylov

2010-09-15

148

2-D phase contrast imaging of turbulence structure on LHD

CO2 laser-based phase contrast imaging (PCI) equipped with a 6 by 8 element two-dimensional (2-D) array of photoconductors is used on the large helical device (LHD) for studying plasma density microfluctuations. Observing 2-D structures of turbulence and strong magnetic shear along the viewing line on LHD permit conversion of a 2-D-PCI image to a 2-D picture of the radial distribution

Leonid N. Vyacheslavov; K. Tanaka; A. L. Sanin; K. Kawahata; C. Michael; T. Akiyama

2005-01-01

149

Numerical Simulation of Slinger Combustor Using 2-D Axisymmetric Computational Model

NASA Astrophysics Data System (ADS)

Small-size turbojet engines have difficulties in maintaining the chemical reaction due to the limitation of chamber size. The combustion chamber is generally designed to improve the reaction efficiency by the generation of vortices in the chamber and to enhance air-fuel mixing characteristics. In the initial stage of designing the combustor, analysis of the 3-D full configuration is not practical due to the huge time consuming computation and grid generation followed by modifications of the geometry. In the present paper, an axisymmetric model maintaining geometric similarity and flow characteristic of 3-D configuration is developed. Based on numerical results from the full 3-D configuration, model reduction is achieved toward 2-D axisymmetric configuration. In the modeling process, the area and location of each hole in 3-D full configuration are considered reasonably and replaced to the 2-D axisymmetric model. By using the 2-D axisymmetric model, the factor that can affect the performance is investigated with the assumption that the flow is non-reacting and turbulent. Numerical results from the present model show a good agreement with numerical results from 3-D full configuration model such as existence of vortex pair in forward region and total pressure loss. By simplifying the complex 3-D model, computing time can be remarkably reduced and it makes easy to find effects of geometry modification.

Lee, Semin; Park, Soo Hyung; Lee, Donghun

2010-06-01

150

Simplified 2D Bidomain Model of Whole Heart Electrical Activity and ECG Generation

NASA Astrophysics Data System (ADS)

The aim of this study was the development of a geometrically simple and highly computationally-efficient two dimensional (2D) biophysical model of whole heart electrical activity, incorporating spontaneous activation of the sinoatrial node (SAN), the specialized conduction system, and realistic surface ECG morphology computed on the torso. The FitzHugh-Nagumo (FHN) equations were incorporated into a bidomain finite element model of cardiac electrical activity, which was comprised of a simplified geometry of the whole heart with the blood cavities, the lungs and the torso as an extracellular volume conductor. To model the ECG, we placed four electrodes on the surface of the torso to simulate three Einthoven leads VI, VII and VIII from the standard 12-lead system. The 2D model was able to reconstruct ECG morphology on the torso from action potentials generated at various regions of the heart, including the sinoatrial node, atria, atrioventricular node, His bundle, bundle branches, Purkinje fibers, and ventricles. Our 2D cardiac model offers a good compromise between computational load and model complexity, and can be used as a first step towards three dimensional (3D) ECG models with more complex, precise and accurate geometry of anatomical structures, to investigate the effect of various cardiac electrophysiological parameters on ECG morphology.

Sovilj, Siniša; Magjarevi?, Ratko; Abed, Amr Al; Lovell, Nigel H.; Dokos, Socrates

2014-06-01

151

Interactive Transformation of 2D Vector Data Eduard Grller

shape. The presented program enables the investigation of 2D crossÂsections of, e.g., insect bodies restricts himself to 2D transformations. The manipulation, distortion and transformation of 2D raster image data has become quite popular in computer graphics in recent years. [2] deals with image warping which

152

Laboratory Experiments On Continually Forced 2d Turbulence

There has been much recent interest in the advection of tracers by 2D turbulence in geophysical flows. While there is a large body of literature on decaying 2D turbulence or forced 2D turbulence in unbounded domains, there have been very few studies of forced turbulence in bounded domains. In this study we present new experimental results from a continuously forced

M. G. Wells; H. J. H. Clercx; G. J. F. Van Heijst

2002-01-01

153

A New 2-D DOA Estimation Algorithm for Noncircular Signals

A novel 2D direction finding algorithm for noncircular signals using two parallel linear arrays called extended rank reduction (ERARE) algorithm is presented in this paper. The proposed method needs only 1D search for joint azimuth and elevation estimation. The 2D angles estimated by ERARE are paired automatically. The estimation precision of 2D angles by ERARE algorithm is better than the

Jian Liu; Zhitao Huang; Yiyu Zhou

2007-01-01

154

A 7090 FORTRAN program for the calculation of the steady-state, ; rotationally symmetric temperature field in an inhomogeneous cylindrical body, in ; which heat production, radiation in narrow gaps, and heat conduction with ; temperature and direction dependent conduction coefficients may occur. The body ; can be divided into at most 70 regions of constant heat production rate and ;

B. H. Boonstra; F. W. Hoff; H. P. Struch

1963-01-01

155

AN INTRODUCTION TO SYMPLECTIC GEOMETRY,

AN INTRODUCTION TO SYMPLECTIC GEOMETRY, HAMILTON SYSTEMS, AND COMPLEX GEOMETRY Rainer Schimming Szczecin 2002 #12; AN INTRODUCTION TO SYMPLECTIC GEOMETRY, HAMILTON SYSTEMS, AND COMPLEX GEOMETRY Rainer Poisson and symplectic geometries 8 2.1 Poisson manifolds

SchÃ¼rmann, Michael

156

ORMDIN. 2-D Nonlinear Inverse Heat Conduction

ORMDIN is a finite-element program developed for two-dimensional nonlinear inverse heat conduction analysis as part of the Oak Ridge National Laboratory Pressurized Water Reactor Blowdown Heat Transfer (BDHT) program. One of the primary objectives of the program was to determine the transient surface temperature and surface heat flux of fuel pin simulators from internal thermocouple signals obtained during a loss-of-coolant accident experiment in the Thermal-Hydraulic Test Facility (THTF). ORMDIN was designed primarily to perform a transient two-dimensional nonlinear inverse heat conduction analysis of the THTF bundle 3 heater rod; however, it can be applied to other cylindrical geometries for which the thermophysical properties are prescribed functions of temperature. The program assumes that discretized temperature histories are provided at three thermocouple locations in the interior of the cylinder. Concurrent with the two-dimensional analysis, ORMDIN also generates one-dimensional solutions for each of the three thermocouple radial planes.

Bass, B.R. [Oak Ridge Gaseous Diffusion Plant, Oak Ridge, TN (United States)

1990-05-01

157

2D-To-3D Stereoscopic Conversion: Depth-Map Estimation in a 2D Single-View Image

2D-To-3D Stereoscopic Conversion: Depth-Map Estimation in a 2D Single-View Image Jaeseung Koa to estimate the relative depth map in a single- view image for the 2D-To-3D conversion technique depth map with these two cues and then refine the depth map by post-processing. Finally, a stereoscopic

Kim, Yong Jung

158

The ac response of a 2-D electron gas on liquid helium in a magnetic field

NASA Astrophysics Data System (ADS)

The low frequency ac response of a 2-D electron gas on liquid helium in a magnetic field is analysed in terms of ? xx and ? xy , the components of the magnetoresistivity tensor. The electrons are screened by parallel electrodes and the system forms a 2-D transmission line. The 2-D wave equation is solved numerically for a bounded electron sheet in a rectangular geometry which is excited by one of the electrodes. For ??? 1, where ? is a relaxation time, heavily damped voltage waves propagate along the transmission line. In a field these waves propagate along the edges of the electron sheet with characteristic decay lengths or 2-D skin depths, parallel and perpendicular to the edges, which depend on ? xx and ? xy . The effects of these skin depths on measurements of the magnetoresistance and ac Hall effect are demonstrated. The relationship to the dc Hall effect and to edge magnetoplasmons is shown. The effects of incomplete screening, density inhomogeneities and edge capacitance are also discussed.

Lea, M. J.; Stone, A. O.; Fozooni, P.; Frost, J.

1991-10-01

159

Influence of individual cell motility on the 2D front roughness dynamics of tumour cell colonies.

The dynamics of in situ 2D HeLa cell quasi-linear and quasi-radial colony fronts in a standard culture medium is investigated. For quasi-radial colonies, as the cell population increased, a kinetic transition from an exponential to a constant front average velocity regime was observed. Special attention was paid to individual cell motility evolution under constant average colony front velocity looking for its impact on the dynamics of the 2D colony front roughness. From the directionalities and velocity components of cell trajectories in colonies with different cell populations, the influence of both local cell density and cell crowding effects on individual cell motility was determined. The average dynamic behaviour of individual cells in the colony and its dependence on both local spatio-temporal heterogeneities and growth geometry suggested that cell motion undergoes under a concerted cell migration mechanism, in which both a limiting random walk-like and a limiting ballistic-like contribution were involved. These results were interesting to infer how biased cell trajectories influenced both the 2D colony spreading dynamics and the front roughness characteristics by local biased contributions to individual cell motion. These data are consistent with previous experimental and theoretical cell colony spreading data and provide additional evidence of the validity of the Kardar-Parisi-Zhang equation, within a certain range of time and colony front size, for describing the dynamics of 2D colony front roughness. PMID:24893945

Muzzio, N E; Pasquale, M A; González, P H; Arvia, A J

2014-06-01

160

2D/3D facial feature extraction

NASA Astrophysics Data System (ADS)

We propose and compare three different automatic landmarking methods for near-frontal faces. The face information is provided as 480x640 gray-level images in addition to the corresponding 3D scene depth information. All three methods follow a coarse-to-fine suite and use the 3D information in an assist role. The first method employs a combination of principal component analysis (PCA) and independent component analysis (ICA) features to analyze the Gabor feature set. The second method uses a subset of DCT coefficients for template-based matching. These two methods employ SVM classifiers with polynomial kernel functions. The third method uses a mixture of factor analyzers to learn Gabor filter outputs. We contrast the localization performance separately with 2D texture and 3D depth information. Although the 3D depth information per se does not perform as well as texture images in landmark localization, the 3D information has still a beneficial role in eliminating the background and the false alarms.

Çinar Akakin, Hatice; Ali Salah, Albert; Akarun, Lale; Sankur, Bülent

2006-02-01

161

The measurement of force distributions in sandpiles provides a useful way to test concepts and models of the way forces propagate within noncohesive granular materials. Recent theory by Bouchaud et al. implies that the internal structure of a heap (and therefore the force pathway) is a strong function of the construction history. In general, it is difficult to obtain information that could test this idea from 3D granular experiments except at boundaries. However, 2D systems, such as those used here, can yield information on forces and particle arrangements in the interior of a sample. We obtain position and force information through the use of photoelastic particles. These experiments show that the history of the heap formation has a dramatic effect on the arrangement of particles (texture) and a weaker but clear effect on the forces within the sample. Specifically, heaps prepared by pouring from a point source show strong anisotropy in the contact angle distribution. Depending on additional details, they show a stress dip near the center. Heaps formed from a broad source show relatively little contact angle anisotropy and no indication of a stress dip.

Junfei Geng; Emily Longhi; R. P. Behringer; D. W. Howell

2003-04-03

162

Amoeboid motion in confined geometry

Cells of the immune system, as well as cancer cells, migrating in confined environment of tissues undergo frequent shape changes (described as amoeboid motion) that enable them to move forward through these porous media without the assistance of adhesion sites. In other words, they perform amoeboid swimming (AS) while using extracellular matrices and cells of tissues as support. We introduce a simple model of AS in a confined geometry solved by means of 2D numerical simulations. We find that confinement promotes AS, unless being so strong that it restricts shape change amplitude. A straight AS trajectory in the channel is found to be unstable, and ample lateral excursions of the swimmer prevail. For weak confinement, these excursions are symmetric, while they become asymmetric at stronger confinement, whereby the swimmer is located closer to one of the two walls. This is a spontaneous symmetry-breaking bifurcation. We find that there exists an optimal confinement for migration. We provide numerical results as...

Wu, Hao; Hu, Wei-Fan; Farutin, Alexander; Rafaï, Salima; Lai, Ming-Chih; Peyla, Philippe; Misbah, Chaouqi

2015-01-01

163

Transmutation of Pure 2-D Supergravity Into Topological 2-D Gravity and Other Conformal Theories

We consider the BRST and superconformal properties of the ghost action of 2-D supergravity. Using the background spin structure on the worldsheet, we show that this action can be transformed by canonical field transformations to reach other conformal models such as the 2-D topological gravity or the chiral models for which the gauge variation of the action reproduces the left or right conformal anomaly. Our method consists in using the gravitino and its ghost as fundamental blocks to build fields with different conformal weights and statistics. This indicates in particular that the twisting of a conformal model into another one can be classically interpreted as a change of "field representation" of the superconformal symmetry.

Laurent Baulieu

1992-06-04

164

Learning Geometry through Dynamic Geometry Software

ERIC Educational Resources Information Center

In this article, the author investigates effective teaching and learning of geometrical concepts using dynamic geometry software (DGS). Based from her students' reactions to her project, the author found that her students' understanding of the concepts was better than if they had learned geometry through paper-based tasks. However, mixing computer…

Forsythe, Sue

2007-01-01

165

Design of optimal and ideal 2-D concentrators with the collector immersed in a dielectric tube

NASA Astrophysics Data System (ADS)

A method is presented for designing ideal and optimal 2-D concentrators when the collector is placed inside a dielectric tube, for the particular case of a bifacial solar collector. The prototype 2-D (cylindrical geometry) concentrator is the compound parabolic concentrator or CPC, and from the beginning of development, it was found by Winston (1978) that filling up the concentrator with a transparent dielectric medium results in a big improvement of the optical properties. The method reported here is based on the extreme ray principle of design and avoids the use of differential equations by means of a proper appliction of Fermat's principle. One advantage of these concentrators is that they allow the size to be small compared with classical CPCs.

Minano, J. C.; Ruiz, J. M.; Luque, A.

1983-12-01

166

NSDL National Science Digital Library

The Geometry Junkyard website provides a broad introduction to the specifics of geometry. The site, designed by David Eppstein of UC-Irvine, provides all the basics of geometry for students and teachers alike. Topics range from the mathematics of shapes to fractals and multi-dimensional geometry, to name only a few. Also provided are various lesson plans for different levels of education. The information on this site could be used to build lesson plans, to design projects, or to better understand the basics of college-level geometry. This simple website will be useful for geometry enthusiasts of all levels.

Eppstein, David

167

Pythagoras' Theorem on a 2D-Lattice from a "Natural" Dirac Operator and Connes' Distance Formula

One of the key ingredients of A. Connes' noncommutative geometry is a generalized Dirac operator which induces a metric(Connes' distance) on the state space. We generalize such a Dirac operator devised by A. Dimakis et al, whose Connes' distance recovers the linear distance on a 1D lattice, into 2D lattice. This Dirac operator being "naturally" defined has the so-called "local eigenvalue property" and induces Euclidean distance on this 2D lattice. This kind of Dirac operator can be generalized into any higher dimensional lattices.

Jian Dai; Xing-Chang Song

2001-01-15

168

Pythagoras' Theorem on a 2D-Lattice from a "Natural" Dirac Operator and Connes' Distance Formula

One of the key ingredients of A. Connes' noncommutative geometry is a generalized Dirac operator which induces a metric(Connes' distance) on the state space. We generalize such a Dirac operator devised by A. Dimakis et al, whose Connes' distance recovers the linear distance on a 1D lattice, into 2D lattice. This Dirac operator being "naturally" defined has the so-called "local eigenvalue property" and induces Euclidean distance on this 2D lattice. This kind of Dirac operator can be generalized into any higher dimensional lattices.

Dai, J; Dai, Jian; Song, Xing-Chang

2001-01-01

169

3D facial reconstruction systems attempt to reconstruct 3D facial models of individuals from their 2D photographic images or video sequences. Currently published face recognition systems, which exhibit well-known deficiencies, are largely based on 2D facial images, although 3D image capture systems can better encapsulate the 3D geometry of the human face. Accordingly, face recognition research is gradually shifting from the

Martin D. Levine; Yingfeng

2009-01-01

170

3-D Ray-tracing and 2-D Fokker-Planck Simulations of Radiofrequency Application to Tokamak Plasmas

A state of the art numerical tool has been developed to simulate the propagation and the absorption of coexisting different types of waves in a tokamak geometry. The code includes a numerical solution of the three-dimensional (R, Z, {Phi}) toroidal wave equation for the electric field of the different waves in the WKBJ approximation. At each step of integration, the two-dimensional (v{sub {parallel}}, v{sub {perpendicular}}) Fokker-Planck equation is solved in the presence of quasilinear diffusion coefficients. The electron Landau damping of the waves is modeled taking into account the interaction of the wave electric fields with the quasilinearly modified distribution function. Consistently, the code calculates the radial profiles of non-inductively generated current densities, the transmitted power traces and the total power damping curves. Synergistic effects among the different type of waves (e.g., lower hybrid and ion Bernstein waves) are studied through the separation of the contributions of the single wave from the effects due to their coexistence.

A. Cardinali; F. Paoletti; S. Bernabei

1999-05-01

171

The Hartle-Hawking wave function in 2d causal set quantum gravity

We define the Hartle-Hawking no-boundary wave function for causal set quantum gravity over the discrete analogs of spacelike hypersurfaces. Using Markov Chain Monte Carlo and numerical integration methods we analyse this wave function in non perturbative 2d causal set quantum gravity. Our results provide new insights into the role of quantum gravity in the observable universe. We find that non-manifold contributions to the Hartle-Hawking wave function can play a significant role. These discrete geometries exhibit a rapid spatial expansion with respect to the proper time and also possess a spatial homogeneity consistent with our current understanding of the observable universe.

Glaser, Lisa

2014-01-01

172

The Hartle-Hawking wave function in 2d causal set quantum gravity

We define the Hartle-Hawking no-boundary wave function for causal set quantum gravity over the discrete analogs of spacelike hypersurfaces. Using Markov Chain Monte Carlo and numerical integration methods we analyse this wave function in non perturbative 2d causal set quantum gravity. Our results provide new insights into the role of quantum gravity in the observable universe. We find that non-manifold contributions to the Hartle-Hawking wave function can play a significant role. These discrete geometries exhibit a rapid spatial expansion with respect to the proper time and also possess a spatial homogeneity consistent with our current understanding of the observable universe.

Lisa Glaser; Sumati Surya

2014-10-31

173

Integrated Design for Manufacturing of Braided Preforms for Advanced Composites Part I: 2D Braiding

NASA Astrophysics Data System (ADS)

This paper presents a 2D braiding design system for advanced textile structural composites was based on dynamic models. A software package to assist in the design of braided preform manufacturing has been developed. The package allows design parameters (machine speeds, fiber volume fraction, tightness factor, etc.) to be easily obtained and the relationships between said parameters to be demonstrated graphically. The fabirc geometry model (FGM) method was adopted to evaluate the mechanical properties of the composites. Experimental evidence demonstrates the success of the use of dynamic models in the design software for the manufacture of braided fabric preforms.

Gao, Yan Tao; Ko, Frank K.; Hu, Hong

2013-12-01

174

Functional Characterization of a First Avian Cytochrome P450 of the CYP2D Subfamily (CYP2D49)

The CYP2D family members are instrumental in the metabolism of 20–25% of commonly prescribed drugs. Although many CYP2D isoforms have been well characterized in other animal models, research concerning the chicken CYP2Ds is limited. In this study, a cDNA encoding a novel CYP2D enzyme (CYP2D49) was cloned from the chicken liver for the first time. The CYP2D49 cDNA contained an open reading frame of 502 amino acids that shared 52%–57% identities with other CYP2Ds. The gene structure and neighboring genes of CYP2D49 are conserved and similar to those of human CYP2D6. Additionally, similar to human CYP2D6, CYP2D49 is un-inducible in the liver and expressed predominantly in the liver, kidney and small intestine, with detectable levels in several other tissues. Metabolic assays of the CYP2D49 protein heterologously expressed in E. coli and Hela cells indicated that CYP2D49 metabolized the human CYP2D6 substrate, bufuralol, but not debrisoquine. Moreover, quinidine, a potent inhibitor of human CYP2D6, only inhibited the bufuralol 1?-hydroxylation activity of CYP2D49 to a negligible degree. All these results indicated that CYP2D49 had functional characteristics similar to those of human CYP2D6 but measurably differed in the debrisoquine 4?-hydroxylation and quinidine inhibitory profile. Further structure-function investigations that employed site-directed mutagenesis and circular dichroism spectroscopy identified the importance of Val-126, Glu-222, Asp-306, Phe-486 and Phe-488 in keeping the enzymatic activity of CYP2D49 toward bufuralol as well as the importance of Asp-306, Phe-486 and Phe-488 in maintaining the conformation of CYP2D49 protein. The current study is only the first step in characterizing the metabolic mechanism of CYP2D49; further studies are still required. PMID:22675558

Yang, Qi; Chen, Qingmei; Deng, Yiqun

2012-01-01

175

NSDL National Science Digital Library

Geometry and Topology is "a fully refereed international journal dealing with all aspects of geometry and topology and their applications." The publisher, Geometry & Topology Publications (GTP), is a non-profit organization based in the Mathematics Department of the University of Warwick at Coventry, UK. Visitors can browse the journal, available free of charge electronically, or search by keyword or author. The moderate collection within the Geometry and Topology Monographs series includes research monographs and refereed conference proceedings.

176

Spectral Geometry Bruno Iochum

Spectral Geometry Bruno Iochum Aix-Marseille UniversitÃ©, CNRS UMR 7332, CPT, 13288 Marseille France Abstract The goal of these lectures is to present some fundamentals of noncommutative geometry looking primary objects defined for manifolds will be generalized to reach the level of noncommutative geometry

Paris-Sud XI, UniversitÃ© de

177

TRIANGLES IN HYPERBOLIC GEOMETRY

This paper derives the Law of Cosines, Law of Sines, and the Pythagorean Theorem for triangles in Hyperbolic Geometry. The Poincar e model for Hyperbolic Geometry is used. In order to accomplish this the paper reviews Inversion in Hyperbolic Geometry, Radical Axes and Powers of circles and expressions for hyperbolic cosine, hyperbolic sine, and hyperbolic tangent. A brief history of

LAURA VALAAS

178

Quantifying tomb geometries in resistivity images using watershed algorithms

Quantifying the geometries (defined here as width, height and depth of burial) of archeological structures within resistivity models produced as a result of the regularization constraints used in most inversion algorithms is difficult, especially when structures are closely spaced. Here we apply the watershed by simulated immersion method of boundary detection to smooth 2D resistivity images generated for synthetic and

Mehrez Elwaseif; Lee Slater

2010-01-01

179

An Application of Geostatistics and Fractal Geometry for Reservoir Characterization

This paper presents an application of geostatistics and fractal geometry concepts for 2D characterization of rock properties (k and Ï) in a dolomitic, layered-cake reservoir. The results indicate that lack of closely spaced data yield effectively random distributions of properties. Further, incorporation of geology reduces uncertainties in fractal interpolation of wellbore properties.

Yngve Aasum; Mohan Kelkar; Surendra Gupta

1991-01-01

180

The first crisis in the geometry arose in the beginning of XIXth century, when the mathematicians rejected the non-Euclidean geometry as a possible geometry of the real world. Now we observe unreasonable rejection of the non-Riemannian geometry by the official representatives of the contemporary geometry. Class of the Riemannian geometries appears to be too narrow for physical applications. The microcosm physics needs expansion of the class of possible geometries appropriate for the role of space-time geometry. In the framework of the non-Riemannian geometry one can construct the space-time geometry, where the motion of free particles is primordially stochastic, and this stochasticity depends on the particle mass. At the same time the geometry in itself is not stochastic in the sense that the space-time intervals are deterministic. Principles of quantum mechanics can be deduced from such a space-time geometry. The crisis situation in geometry appears to be connected with some preconceptions concerning the foundation of the geometry. The preconceptions as well as the crisis generated by them are not purely scientific phenomena. The human factor (social aspect) is rather strong in the crisis phenomena. The preconceptions and the human factor appear to be so strong, that usual logical arguments are not perceived, and the usual formal mathematical language appears to be inappropriate for perception of an analysis of the crisis origin and of a possibility of its overcoming. In the paper the history and motives of the non-Riemannian geometry construction are presented. There is a hope that such a less formal way of presentation helps to understand and to overcome the existing preconceptions.

Yuri A. Rylov

2005-03-14

181

Proper time is stochastic time in 2d quantum gravity

We show that proper time, when defined in the quantum theory of 2d gravity, becomes identical to the stochastic time associated with the stochastic quantization of space. This observation was first made by Kawai and collaborators in the context of 2d Euclidean quantum gravity, but the relation is even simpler and more transparent in he context of 2d gravity formulated in the framework of CDT (causal dynamical triangulations).

J. Ambjorn; R. Loll; Y. Watabiki; W. Westra; S. Zohren

2009-11-21

182

Advances in 1D and 2D thermoelectric materials

Recent advances in our understanding of 1D and 2D thermoelectric materials in the form of quantum wires (1D) and quantum wells (2D) are reviewed, with emphasis given to the physical mechanisms responsible for the enhanced thermoelectric figure of merit (ZT) in these low dimensional systems. Starting with 2D superlattices, progress in demonstrating proof-of-principle in the PbTe\\/Pb1-xEux Te and Si\\/Si1-xGex systems

M. S. Dresselhaus; Y. M. Lin; G. Dresselhaus; X. Sun; Z. Zhang; S. B. Cronin; T. Koga; J. Y. Ying

1999-01-01

183

Update on 2-D array transducers for medical ultrasound

l½-D and 2-D arrays offer a myriad of new imaging modalities and benefits when compared to the linear array. However, with added benefits come many problems and challenges and l½-D and 2-D arrays are no exception. The authors give possible solutions to a number of these challenges. The increase in transducer channels needed in a 1½-D and 2-D array can

Stephen W. Smith; Richard E. Davidsen; Charles D. Emery; Richard L. Goldberg; Edward D. Light

1995-01-01

184

Effects of Nozzle Geometry on Cavitation in Nozzles of Pressure Atomizers

The effects of nozzle geometry on cavitation in the nozzle of pressure atomizers and the liquid jet are examined using various two-dimensional (2D) nozzles with different geometries. Then, whether or not the conventional cavitation numbers can be used to predict the formation of supercavitation, in which liquid jet atomization is enhanced, is examined. As a result, we confirm that (1)

Akira Sou; Muhammad Ilham Maulana; Kenji Isozaki; Shigeo Hosokawa; Akio Tomiyama

2008-01-01

185

Mechanical characterization of 2D, 2D stitched, and 3D braided/RTM materials

NASA Technical Reports Server (NTRS)

Braided composite materials have potential for application in aircraft structures. Fuselage frames, floor beams, wing spars, and stiffeners are examples where braided composites could find application if cost effective processing and damage tolerance requirements are met. Another important consideration for braided composites relates to their mechanical properties and how they compare to the properties of composites produced by other textile composite processes being proposed for these applications. Unfortunately, mechanical property data for braided composites do not appear extensively in the literature. Data are presented in this paper on the mechanical characterization of 2D triaxial braid, 2D triaxial braid plus stitching, and 3D (through-the-thickness) braid composite materials. The braided preforms all had the same graphite tow size and the same nominal braid architectures, (+/- 30 deg/0 deg), and were resin transfer molded (RTM) using the same mold for each of two different resin systems. Static data are presented for notched and unnotched tension, notched and unnotched compression, and compression after impact strengths at room temperature. In addition, some static results, after environmental conditioning, are included. Baseline tension and compression fatigue results are also presented, but only for the 3D braided composite material with one of the resin systems.

Deaton, Jerry W.; Kullerd, Susan M.; Portanova, Marc A.

1993-01-01

186

The interconnection between the geometry of biological tissue (BT) structure and their polarization properties has been studied. It has been shown that for physiologically normal BT, the polarization properties of radiation scattered on architectonic nets formed by protein fibrils have a fractal character. Pathological changes of BT architectonics are accompanied by the transformation of self-similar structure of 2D Mueller-matrix elements

O. V. Angelsky; Yu Ya Tomka; A. G. Ushenko; Ye G. Ushenko; Yu A. Ushenko

2005-01-01

187

Syndrome identification based on 2D analysis Stefan Boehringer*,1

; Cri-du-chat syndrome; SmithÂLemliÂOpitz syndrome; Sotos syndrome; Microdeletion 22q11.2; NoonanARTICLE Syndrome identification based on 2D analysis software Stefan Boehringer*,1 , Tobias Vollmar 2D pictures of patients each being affected with one of 10 syndromes (fragile X syndrome; Cornelia

WÃ¼rtz, Rolf P.

188

Integrating Mobile Multimedia into Textbooks: 2D Barcodes

ERIC Educational Resources Information Center

The major goal of this study was to empirically compare text-plus-mobile phone learning using an integrated 2D barcode tag in a printed text with three other conditions described in multimedia learning theory. The method examined in the study involved modifications of the instructional material such that: a 2D barcode was used near the text, the…

Uluyol, Celebi; Agca, R. Kagan

2012-01-01

189

A 2D Human Body Model Dressed in Eigen Clothing

A 2D Human Body Model Dressed in Eigen Clothing Peng Guan Oren Freifeld Michael J. Black estimation of people in monocular images are widely studied. Two-dimensional mod- els of the human body. The resulting generative model captures realistic human forms in monocular images and is used to infer 2D body

Black, Michael J.

190

The conversion of existing 2D images to 3D is proving commercially viable and fulfills the growing need for high quality stereoscopic images. This approach is particularly effective when creating content for the new generation of autostereoscopic displays that require multiple stereo images. The dominant technique for such content conversion is to develop a depth map for each frame of 2D

Philip V. Harman; Julien Flack; Simon Fox; Mark Dowley

2002-01-01

191

Compression of 2-D Biomedical Images 7.1. Introduction

Chapter 7 Compression of 2-D Biomedical Images 7.1. Introduction On a daily basis, large amounts and Marie BABEL. #12;156 Compression of Biomedical Images and Signals 7.2. Reversible compression of medical Tree Predictive Coding) [ROB 97], #12;Compression of 2-D Biomedical Images 157 - methods based on

Paris-Sud XI, UniversitÃ© de

192

Regulation of ligands for the NKG2D activating receptor

NKG2D is an activating receptor expressed by all NK cells and subsets of T cells. It serves as a major recognition receptor for detection and elimination of transformed and infected cells and participates in the genesis of several inflammatory diseases. The ligands for NKG2D are self-proteins that are induced by pathways that are active in certain pathophysiological states. NKG2D ligands are regulated transcriptionally, at the level of mRNA and protein stability, and by cleavage from the cell surface. In some cases, ligand induction can be attributed to pathways that are activated specifically in cancer cells or infected cells. We review the numerous pathways that have been implicated in the regulation of NKG2D ligands, discuss the pathologic states in which those pathways are likely to act, and attempt to synthesize the findings into general schemes of NKG2D ligand regulation in NK cell responses to cancer and infection. PMID:23298206

Raulet, David H.; Gasser, Stephan; Gowen, Benjamin G.; Deng, Weiwen; Jung, Heiyoun

2014-01-01

193

Developing Mobile BIM/2D Barcode-Based Automated Facility Management System

Facility management (FM) has become an important topic in research on the operation and maintenance phase. Managing the work of FM effectively is extremely difficult owing to the variety of environments. One of the difficulties is the performance of two-dimensional (2D) graphics when depicting facilities. Building information modeling (BIM) uses precise geometry and relevant data to support the facilities depicted in three-dimensional (3D) object-oriented computer-aided design (CAD). This paper proposes a new and practical methodology with application to FM that uses an integrated 2D barcode and the BIM approach. Using 2D barcode and BIM technologies, this study proposes a mobile automated BIM-based facility management (BIMFM) system for FM staff in the operation and maintenance phase. The mobile automated BIMFM system is then applied in a selected case study of a commercial building project in Taiwan to verify the proposed methodology and demonstrate its effectiveness in FM practice. The combined results demonstrate that a BIMFM-like system can be an effective mobile automated FM tool. The advantage of the mobile automated BIMFM system lies not only in improving FM work efficiency for the FM staff but also in facilitating FM updates and transfers in the BIM environment. PMID:25250373

Chen, Yen-Pei

2014-01-01

194

Assessment of an ASTER-generated DEM for 2D hydrodynamic flood modeling

NASA Astrophysics Data System (ADS)

Flood modeling often provides inputs to flood hazard management. In the present work we studied the flooding characteristics in the data scarce region of the Lake Tana basin at the source of the Blue Nile River. The study required to integrate remote sensing, GIS with a two-dimensional (2D) module of the SOBEK flood model. The resolution of the topographic data in many areas, such as the Lake Tana region, is commonly too poor to support detailed 2D hydrodynamic modeling. To overcome such limitations, we used a Digital Elevation Model (DEM) which was generated from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image. A GIS procedure is developed to reconstruct the river terrain and channel bathymetry. The results revealed that a representation of the river terrain largely affects the simulated flood characteristics. Simulations indicate that effects of Lake Tana water levels propagate up to 13 km along the Ribb River. We conclude that a 15 m resolution ASTER DEM can serve as an input to detailed 2D hydrodynamic modeling in data scarce regions. However, for this purpose it is necessary to accurately reconstruct the river terrain geometry and flood plain topography based on ground observations by means of a river terrain model.

Tarekegn, Tesfaye Haimanot; Haile, Alemseged Tamiru; Rientjes, Tom; Reggiani, P.; Alkema, Dinand

2010-12-01

195

AnisWave2D: User's Guide to the 2d Anisotropic Finite-DifferenceCode

This document describes a parallel finite-difference code for modeling wave propagation in 2D, fully anisotropic materials. The code utilizes a mesh refinement scheme to improve computational efficiency. Mesh refinement allows the grid spacing to be tailored to the velocity model, so that fine grid spacing can be used in low velocity zones where the seismic wavelength is short, and coarse grid spacing can be used in zones with higher material velocities. Over-sampling of the seismic wavefield in high velocity zones is therefore avoided. The code has been implemented to run in parallel over multiple processors and allows large-scale models and models with large velocity contrasts to be simulated with ease.

Toomey, Aoife

2005-01-06

196

NSDL National Science Digital Library

Provided by David Eppstein, professor of Information and Computer Science at the University of California-Irvine, the Geometry Junkyard is a metasite covering classical geometry theory and current research in the area of computation geometry. A few examples of the many topics included in the Geometry Junkyard are: combination geometry, fractals, multi-dimensional geometry, and open problems (most of which are illustrated with diagrams). Dr. Eppstein's thoughtful selection of links point users to numerous discussions and solutions to problems; in addition, he has added several pages on topics not well covered (My Own Junk), and has highlighted newly added material (New Junk). This site is more of a gold mine than a junkyard, based on the vast amount of information provided and the fun spin placed on many of the topics.

197

NASA Astrophysics Data System (ADS)

Generalized Kähler geometry is the natural analogue of Kähler geometry, in the context of generalized complex geometry. Just as we may require a complex structure to be compatible with a Riemannian metric in a way which gives rise to a symplectic form, we may require a generalized complex structure to be compatible with a metric so that it defines a second generalized complex structure. We prove that generalized Kähler geometry is equivalent to the bi-Hermitian geometry on the target of a 2-dimensional sigma model with (2, 2) supersymmetry. We also prove the existence of natural holomorphic Courant algebroids for each of the underlying complex structures, and that these split into a sum of transverse holomorphic Dirac structures. Finally, we explore the analogy between pre-quantum line bundles and gerbes in the context of generalized Kähler geometry.

Gualtieri, Marco

2014-10-01

198

What is Computational Geometry?

Voronoi Diagrams, Springer-Verlag, 1989.[Ko86] Kostovskii, A., Geometrical Constructions with Compasses Only, Mir Publishers,Moscow, 1986.[Kr92] Kreveld, M. van, New Results on Data Structures in Computational Geometry, Universityof Utrecht, 1992.[KS92] Karasik, Y. B. and Sharir, M., "Optical computational geometry," Proc. 8th ACM Symposiumon Computational Geometry, Berlin, June 10-12, 1992, pp. 232-241.[Le02] Lemoine, E., Geometrographie, C. Naud, Paris, 1902.[LPS88] Lenhart, W.,...

Godfried T. Toussaint

199

Developments in special geometry

We review the special geometry of N = 2 supersymmetric vector and hypermultiplets with emphasis on recent developments and applications. A new formulation of the local c-map based on the Hesse potential and special real coordinates is presented. Other recent developments include the Euclidean version of special geometry, and generalizations of special geometry to non-supersymmetric theories. As applications we disucss the proof that the local r-map and c-map preserve geodesic completeness, and the construction of four- and five-dimensional static solutions through dimensional reduction over time. The shared features of the real, complex and quaternionic version of special geometry are stressed throughout.

Thomas Mohaupt; Owen Vaughan

2011-12-13

200

Geometry of thin nematic elastomer sheets.

A thin sheet of nematic elastomer attains 3D configurations depending on the nematic director field upon heating. In this Letter, we describe the intrinsic geometry of such a sheet and derive an expression for the metric induced by general nematic director fields. Furthermore, we investigate the reverse problem of constructing a director field that induces a specified 2D geometry. We provide an explicit recipe for how to construct any surface of revolution using this method. Finally, we show that by inscribing a director field gradient across the sheet's thickness, one can obtain a nontrivial hyperbolic reference curvature tensor, which together with the prescription of a reference metric allows dictation of actual configurations for a thin sheet of nematic elastomer. PMID:25554907

Aharoni, Hillel; Sharon, Eran; Kupferman, Raz

2014-12-19

201

Geometry of Thin Nematic Elastomer Sheets

NASA Astrophysics Data System (ADS)

A thin sheet of nematic elastomer attains 3D configurations depending on the nematic director field upon heating. In this Letter, we describe the intrinsic geometry of such a sheet and derive an expression for the metric induced by general nematic director fields. Furthermore, we investigate the reverse problem of constructing a director field that induces a specified 2D geometry. We provide an explicit recipe for how to construct any surface of revolution using this method. Finally, we show that by inscribing a director field gradient across the sheet's thickness, one can obtain a nontrivial hyperbolic reference curvature tensor, which together with the prescription of a reference metric allows dictation of actual configurations for a thin sheet of nematic elastomer.

Aharoni, Hillel; Sharon, Eran; Kupferman, Raz

2014-12-01

202

2D vs. 3D mammography observer study

NASA Astrophysics Data System (ADS)

Breast cancer is the most common type of non-skin cancer in women. 2D mammography is a screening tool to aid in the early detection of breast cancer, but has diagnostic limitations of overlapping tissues, especially in dense breasts. 3D mammography has the potential to improve detection outcomes by increasing specificity, and a new 3D screening tool with a 3D display for mammography aims to improve performance and efficiency as compared to 2D mammography. An observer study using a mammography phantom was performed to compare traditional 2D mammography with this ne 3D mammography technique. In comparing 3D and 2D mammography there was no difference in calcification detection, and mass detection was better in 2D as compared to 3D. There was a significant decrease in reading time for masses, calcifications, and normals in 3D compared to 2D, however, as well as more favorable confidence levels in reading normal cases. Given the limitations of the mammography phantom used, however, a clearer picture in comparing 3D and 2D mammography may be better acquired with the incorporation of human studies in the future.

Fernandez, James Reza F.; Hovanessian-Larsen, Linda; Liu, Brent

2011-03-01

203

Turbulent flow over a surface-mounted 2-D block in thermally-stratified boundary layers

NASA Astrophysics Data System (ADS)

Turbulent boundary-layer flows over complex topography have been of great interest in the atmospheric sciences and wind engineering communities. The geometry of the topography, surface characteristics and atmospheric thermal stability play important roles in determining momentum and scalar flux distribution. Studies of turbulent flow over simplified topography, such as 2-D or 3-D blocks and 2-D or 3-D sinusoidal hills, conducted under neutrally stratified boundary-layer conditions have provided insightful information of fluid dynamics. However, atmospheric thermal stability has rarely been incorporated into laboratory simulations, in particular, wind-tunnel experiments. Extension of such studies in thermally-stratified wind tunnels will fill this gap and advance our understanding of the underlying physics of flow over complex topography. Additionally, experimental data are useful for the development of new parameterizations for surface fluxes and validation of numerical models such as Large-Eddy Simulation (LES). A series of experiments involving neutral and thermally-stratified boundary-layer flows over a surface-mounted 2-D block, conducted at the Saint Anthony Falls Laboratory boundary-layer wind tunnel, will be presented. The 2-D block, with a width to height ratio of 2:1, occupied the lowest 25% of the turbulent boundary layer. Thermal stratification of the boundary layer was achieved by independently controlling the temperature of both the airflow, the test section floor and block surfaces. Measurements using high-resolution PIV, x-wire/cold-wire anemometry, thermal-couples and surface heat flux sensors were made to identify and quantify the turbulent flow properties, including the size of the recirculation zone, coherent vortex structures and the subsequent boundary layer recovery. Emphasis will be put on addressing thermal stability effects on momentum and scalar flux distribution.

Zhang, W.; Markfort, C. D.; Porte-Agel, F.

2013-12-01

204

Extreme-value statistics of 2D chaotic systems

NASA Astrophysics Data System (ADS)

We study the extreme-value statistics of 2D chaotic systems. We consider the extreme value of n phase space points of a 2D chaotic trajectory under a suitably defined norm to order the points and calculate analytically its density. We find that the extreme-value density is non-differentiable on a set of points and the number of such singular points increases with n. However, for identically distributed independent 2D random variables the number of singular points is independent of n.

Valsakumar, M. C.; Satyanarayana, S. V. M.; Kanmani, S.

1998-10-01

205

2-D Shape Representation and Recognition by Lattice Computing Techniques

NASA Astrophysics Data System (ADS)

We consider binary images such that an image includes a single 2-D shape, from which we extract three populations of three different (shape) descriptors, respectively. Each population is represented by an Intervals' Number, or IN for short, in the mathematical lattice (F, ≼ ) of INs. In conclusion, a 2-D shape is represented in the Cartesian product lattice (F 3, ≼ ). We present a 2-D shape classification scheme based on fuzzy lattice reasoning (FLR). Preliminary experimental results have been encouraging. We discuss the potential of Lattice Computing (LC) techniques in image representation and recognition applications.

Kaburlasos, V. G.; Amanatiadis, A.; Papadakis, S. E.

206

Comparison of 2D and 3D gamma analyses

Purpose: As clinics begin to use 3D metrics for intensity-modulated radiation therapy (IMRT) quality assurance, it must be noted that these metrics will often produce results different from those produced by their 2D counterparts. 3D and 2D gamma analyses would be expected to produce different values, in part because of the different search space available. In the present investigation, the authors compared the results of 2D and 3D gamma analysis (where both datasets were generated in the same manner) for clinical treatment plans. Methods: Fifty IMRT plans were selected from the authors’ clinical database, and recalculated using Monte Carlo. Treatment planning system-calculated (“evaluated dose distributions”) and Monte Carlo-recalculated (“reference dose distributions”) dose distributions were compared using 2D and 3D gamma analysis. This analysis was performed using a variety of dose-difference (5%, 3%, 2%, and 1%) and distance-to-agreement (5, 3, 2, and 1 mm) acceptance criteria, low-dose thresholds (5%, 10%, and 15% of the prescription dose), and data grid sizes (1.0, 1.5, and 3.0 mm). Each comparison was evaluated to determine the average 2D and 3D gamma, lower 95th percentile gamma value, and percentage of pixels passing gamma. Results: The average gamma, lower 95th percentile gamma value, and percentage of passing pixels for each acceptance criterion demonstrated better agreement for 3D than for 2D analysis for every plan comparison. The average difference in the percentage of passing pixels between the 2D and 3D analyses with no low-dose threshold ranged from 0.9% to 2.1%. Similarly, using a low-dose threshold resulted in a difference between the mean 2D and 3D results, ranging from 0.8% to 1.5%. The authors observed no appreciable differences in gamma with changes in the data density (constant difference: 0.8% for 2D vs 3D). Conclusions: The authors found that 3D gamma analysis resulted in up to 2.9% more pixels passing than 2D analysis. It must be noted that clinical 2D versus 3D datasets may have additional differences—for example, if 2D measurements are made with a different dosimeter than 3D measurements. Factors such as inherent dosimeter differences may be an important additional consideration to the extra dimension of available data that was evaluated in this study.

Pulliam, Kiley B.; Huang, Jessie Y.; Howell, Rebecca M.; Followill, David; Kry, Stephen F., E-mail: sfkry@mdanderson.org [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center and The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030 (United States); Bosca, Ryan [Department of Imaging Physics, The University of Texas MD Anderson Cancer Center and The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030 (United States)] [Department of Imaging Physics, The University of Texas MD Anderson Cancer Center and The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030 (United States); O’Daniel, Jennifer [Department of Radiation Oncology, Duke University, Durham, North Carolina 27705 (United States)] [Department of Radiation Oncology, Duke University, Durham, North Carolina 27705 (United States)

2014-02-15

207

Cluster algebras in scattering amplitudes with special 2D kinematics

NASA Astrophysics Data System (ADS)

We study the cluster algebra of the kinematic configuration space of an -particle scattering amplitude restricted to the special 2D kinematics. We found that the -point two-loop MHV remainder function in special 2D kinematics depends on a selection of the -coordinates that are part of a special structure of the cluster algebra related to snake triangulations of polygons. This structure forms a necklace of hypercube beads in the corresponding Stasheff polytope. Furthermore at , the cluster algebra and the selection of the -coordinates in special 2D kinematics replicates the cluster algebra and the selection of -coordinates of the two-loop MHV amplitude in 4D kinematics.

Torres, Marcus A. C.

2014-02-01

208

Continental rifting to seafloor spreading: 2D and 3D numerical modeling

NASA Astrophysics Data System (ADS)

Two topics related with continental extension is studied by using numerical modeling methods: (1) Lithospheric mantle stratification changes dynamics of craton extension (2D modeling) and (2) Initial lithospheric rheological structure influences the incipient geometry of the seafloor spreading (3D modeling). (Topic 1) Lithospheric mantle stratification is a common feature in cratonic areas which has been demonstrated by geophysical and geochemical studies. The influence of lithospheric mantle stratification during craton evolution remains poorly understood. We use a 2D thermo-mechanical coupled numerical model to study the influence of stratified lithospheric mantle on craton extension. A rheologically weak layer representing hydrated and/or metasomatized composition is implemented in the lithospheric mantle. Our results show that the weak mantle layer changes the dynamics of lithospheric extension by enhancing the deformation of the overlying mantle and crust and inhibiting deformation of the underlying mantle. Modeling results are compared with North China and North Atlantic cratons. Our work indicates that although the presence of a weak layer may not be sufficient to initiate craton deformation, it enhances deformation by lowering the required extensional plate boundary force. (Topic 2) The process from continental rifting to seafloor spreading is an important step in the Wilson Cycle. Since the rifting to spreading is a continuous process, understanding the inheritance of continental rifting in seafloor spreading is crucial to study the incipient geometry (on a map view) of the oceanic ridge and remains a big challenge. Large extension strain is required to simulate the rifting and spreading processes. Oceanic ridge has a 3D geometry on a map view in nature, which requires 3D studies. Therefore, we employ the three-dimensional numerical modeling method to study this problem. The initial lithospheric rheological structure and the perturbation geometry are two key parameters that we investigated. The modeling results show that the continental rifting history affects the incipient geometry of the seafloor spreading, leading to (1) single straight oceanic ridge, (2) overlapping oceanic ridge and (3) curved oceanic ridge.

Liao, Jie; Gerya, Taras

2014-05-01

209

Progressive geometry compression

We propose a new progressive compression scheme for arbitrary topology, highly detailed and densely sampled meshes arising from geometry scanning. We observe that meshes consist of three distinct components: geometry, parameter, and connectivity information. The latter two do not contribute to the reduction of error in a compression setting. Using semi-regular meshes, parameter and connectivity information can be virtually eliminated.

Andrei Khodakovsky; Peter Schröder; Wim Sweldens

2000-01-01

210

ERIC Educational Resources Information Center

Several interactive geometry software packages are available today to secondary school teachers. An example is The Geometer's Sketchpad[R] (GSP), also known as Dynamic Geometry[R] software, developed by Key Curriculum Press. This numeric based technology has been widely adopted in the last twenty years, and a vast amount of creativity has been…

Lyublinskaya, Irina; Funsch, Dan

2012-01-01

211

geometry texts in the U.S. came to be that way. #12;Geometry and Proof John T. Baldwin Background Hilbert Hilbert's Critique Three Frameworks High School Curriculum My background 1 Model theory research (35 years to change slash & back to just ampersand to get the site.) or just google glencoe. Why does it take six

Baldwin, John T.

212

Some links between turtle geometry and analytic geometry

The computer language LOGO facilitates the teaching of analytic geometry and calculus from the notion of curvature, through its ‘turtle geometry’ facility [2]. We provide some theoretical basis for finding turtle geometry equivalents of familiar curves in analytic geometry, and vice versa, by some simple methods which apparently have not been noticed previously. In particular, we study turtle geometry programs

Neil C. Rowe

1985-01-01

213

We review some aspects of the spinorial geometry approach to the classification of supersymmetric solutions of supergravity theories. In particular, we explain how spinorial geometry can be used to express the Killing spinor equations in terms of a linear system for the fluxes and the geometry of spacetime. The solutions of this linear system express some of the fluxes in terms of the spacetime geometry and determine the conditions on the spacetime geometry imposed by supersymmetry. We also present some of the recent applications like the classification of maximally supersymmetric G-backgrounds in IIB, this includes the most general pp-wave solution preserving 1/2 supersymmetry, and the classification of N=31 backgrounds in ten and eleven dimensions.

U. Gran; J. Gutowski; G. Papadopoulos; D. Roest

2006-12-14

214

NASA Astrophysics Data System (ADS)

A description of the geometry of space-time with all the questions and issues explained without the need for formulas. As such, the author shows that this is indeed geometry, with actual constructions familiar from Euclidean geometry, and which allow exact demonstrations and proofs. The formal mathematics behind these constructions is provided in the appendices. The result is thus not a textbook introducing readers to the theory of special relativity so they may calculate formally, but rather aims to show the connection with synthetic geometry. It presents the relation to projective geometry and uses this to illustrate the starting points of general relativity. Written at an introductory level for undergraduates, this novel presentation will also benefit teaching staff.

Liebscher, Dierck-Ekkehard

2005-04-01

215

Determination of the Hyperfine Structure of N2D(+)

NASA Technical Reports Server (NTRS)

We present new high spectral resolution observations of the N2D+ J = 2 yields 1 and J = 3 yields 2 as well as N2H+ J = 3 yields 2 lines, towards dense molecular cores. The hyperfine structure of the N2H+ and N2D+ transitions is clearly resolved in these sources, in excellent agreement with quantum mechanical calculations. Optical depths are determined from the observed spectra, leading to D/H values of the order of 10 - 30% for the N2D+/N2H+ system. There are a large number of hyperfine components and in addition to providing satellites they contribute to the broadening and asymmetric shapes of the N2H+ and N2D+ line profiles. It is therefore important to take into account the detailed hyperfine structure of the transitions when deducing astrophysical parameters from observed data.

Gerin, Maryvonne; Pearson, John C.; Roueff, Evelyne; Falgarone, Edith; Phillips, Thomas G.

2001-01-01

216

Generation of high quality 2D meshes for given bathymetry

This thesis develops and applies a procedure to generate high quality 2D meshes for any given ocean region with complex coastlines. The different criteria used in determining mesh element sizes for a given domain are ...

Colmenero, Jorge, S.B. Massachusetts Institute of Technology

2014-01-01

217

A 2d spray model with gyroscopic effects. Ayman Moussa

A 2d spray model with gyroscopic effects. Ayman Moussa , Franck Sueur , December 15, 2011 Abstract-type equation and an Euler-type equation: the fluid acts on the dispersed phase through a gyroscopic force

Sueur, Franck

218

Dielectric function of quasi-2D semiconductor nanostructures

The spatial and temporal dispersion of the dielectric function of the electron gas in quasi-2D quantum nanostructures has been studied. Analytical expressions for the dielectric function for a quantum well in the form of a {delta} function and a rectangular well of finite depth are derived for the first time. A criterion for transition to strictly 2D and strictly 3D cases was obtained.

Bazhenov, N. L., E-mail: bazhnil.ivom@mail.ioffe.ru; Mynbaev, K. D.; Zegrya, G. G. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

2007-02-15

219

2D Jet Simulation Testing SUNY Stony Brook

2D Jet Simulation Testing Yan Zhan SUNY Stony Brook Feb 3rd 2014 1 #12;Mesh & Boundary Conditions Width (W) Length (L) Grid # in x (Nx) Grid # in y ( Ny) Total Grid # (Nt) 5D 50D 212 2120 449,440 4D 50D 170 2120 360,400 3D 50D 127 2120 269,240 2D 50D 85 2120 180,200 1D 50D 42 2120 89,040 2 W L axis

McDonald, Kirk

220

Implementation of 2D\\/3D Transformation for Clothing Panel

2D\\/3D transformation for clothing panel is one of most important steps for virtual clothing. And vector mesh generation is one of the basic tasks that complete 2D\\/3D transformation of clothing panel images and virtual clothing designs. Based on the classical methods of generating meshes, an algorithm for generating vector meshes which is suitable for garment panel images was presented. The

Xinrong Hu; Yan Bai; Shuqin Cui; Zhongmin Deng

2009-01-01

221

Implementation and performance analysis of 2D DFT beamspace ESPRIT

The 2D DFT beamspace ESPRIT is a closed form algorithm that provides automatically paired azimuth and elevation angle estimates of multiple sources incident on a uniform rectangular array of antennas. This paper shows how the performance of 2D DFT beamspace ESPRIT can be improved via incorporation of null-steering. Null-steering provides the means for filtering out sources (interferers) in adjacent sectors,

Cherian P. Mathews; M. Haardt; M. D. Zoltowski

1995-01-01

222

Generating a 2D Representation of a Complex Data Structure

NASA Technical Reports Server (NTRS)

A computer program, designed to assist in the development and debugging of other software, generates a two-dimensional (2D) representation of a possibly complex n-dimensional (where n is an integer >2) data structure or abstract rank-n object in that other software. The nature of the 2D representation is such that it can be displayed on a non-graphical output device and distributed by non-graphical means.

James, Mark

2006-01-01

223

RNA folding pathways and kinetics using 2D energy landscapes.

RNA folding pathways play an important role in various biological processes, such as (i) the hok/sok (host-killing/suppression of killing) system in E. coli to check for sufficient plasmid copy number, (ii) the conformational switch in spliced leader (SL) RNA from Leptomonas collosoma, which controls trans splicing of a portion of the [Formula: see text] exon, and (iii) riboswitches-portions of the [Formula: see text] untranslated region of messenger RNA that regulate genes by allostery. Since RNA folding pathways are determined by the energy landscape, we describe a novel algorithm, FFTbor2D, which computes the 2D projection of the energy landscape for a given RNA sequence. Given two metastable secondary structures [Formula: see text] for a given RNA sequence, FFTbor2D computes the Boltzmann probability [Formula: see text] that a secondary structure has base pair distance [Formula: see text] from [Formula: see text] and distance [Formula: see text] from [Formula: see text]. Using polynomial interpolation with the fast Fourier transform, we compute [Formula: see text] in [Formula: see text] time and [Formula: see text] space, which is an improvement over an earlier method, which runs in [Formula: see text] time and [Formula: see text] space. FFTbor2D has potential applications in synthetic biology, where one might wish to design bistable switches having target metastable structures [Formula: see text] with favorable pathway kinetics. By inverting the transition probability matrix determined from FFTbor2D output, we show that L. collosoma spliced leader RNA has larger mean first passage time from [Formula: see text] to [Formula: see text] on the 2D energy landscape, than [Formula: see text] of 20,000 sequences, each having metastable structures [Formula: see text]. Source code and binaries are freely available for download at http://bioinformatics.bc.edu/clotelab/FFTbor2D . The program FFTbor2D is implemented in C++, with optional OpenMP parallelization primitives. PMID:24515409

Senter, Evan; Dotu, Ivan; Clote, Peter

2015-01-01

224

Phylogenetic tree construction based on 2D graphical representation

NASA Astrophysics Data System (ADS)

A new approach based on the two-dimensional (2D) graphical representation of the whole genome sequence [Bo Liao, Chem. Phys. Lett., 401(2005) 196.] is proposed to analyze the phylogenetic relationships of genomes. The evolutionary distances are obtained through measuring the differences among the 2D curves. The fuzzy theory is used to construct phylogenetic tree. The phylogenetic relationships of H5N1 avian influenza virus illustrate the utility of our approach.

Liao, Bo; Shan, Xinzhou; Zhu, Wen; Li, Renfa

2006-04-01

225

Induced geometry from disformal transformation

In this note, we use the disformal transformation to induce a geometry from the manifold which is originally Riemannian. The new geometry obtained here can be considered as a generalization of Weyl integrable geometry. Based on these results, we further propose a geometry which is naturally a generalization of Weyl geometry.

Fang-Fang Yuan; Peng Huang

2015-02-08

226

Induced geometry from disformal transformation

In this note, we use the disformal transformation to induce a geometry from the manifold which is originally Riemannian. The new geometry obtained here can be considered as a generalization of Weyl integrable geometry. Based on these results, we further propose a geometry which is naturally a generalization of Weyl geometry.

Yuan, Fang-Fang

2015-01-01

227

Amoeboid motion in confined geometry

Cells of the immune system, as well as cancer cells, migrating in confined environment of tissues undergo frequent shape changes (described as amoeboid motion) that enable them to move forward through these porous media without the assistance of adhesion sites. In other words, they perform amoeboid swimming (AS) while using extracellular matrices and cells of tissues as support. We introduce a simple model of AS in a confined geometry solved by means of 2D numerical simulations. We find that confinement promotes AS, unless being so strong that it restricts shape change amplitude. A straight AS trajectory in the channel is found to be unstable, and ample lateral excursions of the swimmer prevail. For weak confinement, these excursions are symmetric, while they become asymmetric at stronger confinement, whereby the swimmer is located closer to one of the two walls. This is a spontaneous symmetry-breaking bifurcation. We find that there exists an optimal confinement for migration. We provide numerical results as well as scaling laws. This study raises the question of the relevance of these scenarios to complex situations encountered in vivo.

Hao Wu; Marine Thiébaut; Wei-Fan Hu; Alexander Farutin; Salima Rafaï; Ming-Chih Lai; Philippe Peyla; Chaouqi Misbah

2015-02-13

228

NSDL National Science Digital Library

A physical, proportional geometry that originates from the simple circle. A growing body of architectural and iconographic evidence suggests this geometry was a relatively common tradition and has been practiced for at least 2000 years. The site is divided into four areas: Foundations, Anthropology, Designs, and Education; it introduces this two-dimensional non-random geometry in a connect-the-point format, exploring the intellectual and cultural implications of pre-Columbian geometric traditions in the New World. It also provides a list of European mathematical ramifications of the designs.

Forum, Math; Hardaker, Chris

2000-01-01

229

Complex Algebraic Geometry Jean Gallier

Complex Algebraic Geometry Jean Gallier and Stephen S. Shatz Department of Computer is Geometry & What is Complex Algebraic Geometry? . . . . . . . . . . . . . . . . . . 7 1.2 Local Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 2.3 Hodge I, Analytic Preliminaries

Gallier, Jean

230

Voids in the 2dF Galaxy Redshift Survey

We present an analysis of voids in the 2dF Galaxy Redshift Survey (2dFGRS). This analysis includes identification of void regions and measurement of void statistics. The 2dFGRS is the largest completed redshift survey to date, including a total of 245,591 galaxies covering 1500 deg$^2$ to a median depth of z~0.11. We use the voidfinder algorithm to identify a total of 289 voids in the 2dFGRS with radius larger than 10h^{-1}Mpc. These voids have an average effective radius of 14.89+- 2.65 h^{-1}Mpc in the North Galactic Pole region (NGP) and 15.61+- 2.84h^{-1}Mpc in the South Galactic Pole region (SGP). These voids are extremely underdense, with average density contrast of delta rho/rho= -0.94+-0.02. The centers of voids are even emptier, because the few galaxies within the voids typically lie close to the edges. The total volume of the universe filled by these void regions is approximately 40%. We measure the Void Probability Function (VPF) of the 2dFGRS for volume-limited samples with limiting absolute magnitudes from -16 to -21 in b_J. We measure the Underdensity Probability Function for samples with limiting absolute magnitudes from -18 to -21. We find that the SGP is more underdense than the NGP for all but the brightest sample under consideration. There is good agreement between the VPF's of the Center for Astrophysics Survey and the 2dFGRS. Comparison of VPF's measured for the 2dFGRS with the distribution of simulated dark-matter halos of similar number density indicates that voids in the matter distribution in LCDM simulations are not empty enough. However, semi-analytic models of galaxy formation that include feedback effects yield VPF's that show excellent agreement with the data.

Fiona Hoyle; Michael S. Vogeley

2003-12-19

231

ERIC Educational Resources Information Center

Discussed are the major historical developments of geometry. Euclid, Descartes, Klein's Erlanger Program, Gaus and Riemann, globalization, topology, Elie Cartan, and an application to molecular biology are included as topics. (KR)

Chern, Shiing-Shen

1990-01-01

232

Flyby Geometry Optimization Tool

NASA Technical Reports Server (NTRS)

The Flyby Geometry Optimization Tool is a computer program for computing trajectories and trajectory-altering impulsive maneuvers for spacecraft used in radio relay of scientific data to Earth from an exploratory airplane flying in the atmosphere of Mars.

Karlgaard, Christopher D.

2007-01-01

233

Functional Differential Geometry

Differential geometry is deceptively simple. It is surprisingly easyto get the right answer with unclear and informal symbol manipulation.To address this problem we use computer programs to communicate aprecise understanding ...

Sussman, Gerald Jay

2005-02-02

234

ERIC Educational Resources Information Center

Describes a sixth-grade interdisciplinary geometry unit based on Charles Dickens's "A Christmas Carol". Focuses on finding area, volume, and perimeter, and working with estimation, decimals, and fractions in the context of making gingerbread houses. (ASK)

Emenaker, Charles E.

1999-01-01

235

Exploratorium: Geometry Playground

NSDL National Science Digital Library

You've probably been to a playground, but have you been to the Geometry Playground? It's just as much fun, and it may change the way you think about geometry. Created by the good folks at the Exploratorium in San Francisco, this exhibit is meant to complement the traveling exhibit which has been featured in other science museums around the United States. The exhibit here contains three sections: Seeing, Moving, and Fitting Things Together. In the Seeing exhibit, visitors can make their way through a fine photo essay about the invisible geometry of light, while the Moving section gets interested parties up and exploring geometry with their bodies. Each of these sections has great photo essays, complemented by animations and fun activities.

2012-04-20

236

NSDL National Science Digital Library

"Informal notes" by Kevin Brown on geometry: constructing the heptadecagon, what mirrors do, the golden pentagon, the grazing goat and the lune, Napoleon's theorem, chess boards, Diophantine geodesic boxes, Zeno's mice and the logarithmic spiral, and many more.

Brown, Kevin

2007-12-11

237

Quantum Computation as Geometry

Quantum computers hold great promise, but it remains a challenge to find efficient quantum circuits that solve interesting computational problems. We show that finding optimal quantum circuits is essentially equivalent to finding the shortest path between two points in a certain curved geometry. By recasting the problem of finding quantum circuits as a geometric problem, we open up the possibility of using the mathematical techniques of Riemannian geometry to suggest new quantum algorithms, or to prove limitations on the power of quantum computers.

Michael A. Nielsen; Mark R. Dowling; Mile Gu; Andrew C. Doherty

2006-03-19

238

2D PIC/MC simulations of electrical asymmetry effect in capacitive coupled plasma

NASA Astrophysics Data System (ADS)

Recently a so-called electrical asymmetry effect (EAE), which could achieve high-degree separate control of ion flux and energy in dual-frequency capacitively coupled plasmas, was discovered theoretically by Heil et al. and was confirmed by experiments and theory/numerical simulations later on. However, since there always is a bigger grounded surface area for experiment devices, which reduces the geometrical symmetry, and all the simulations were limited to 1D before, it is, thus, worth studying the EAE when coupling the electrically and geometrically asymmetric discharges theoretically. Here, we perform 2D PIC/MC simulations, which can include both electrically and geometrically asymmetric factors. The EAE on plasma parameters, such as dc self-bias voltage, density profiles, ion energy distribution and power absorption of electron have been examined for different pressures and geometry conditions.

Zhang, Quan-Zhi; Jiang, Wei; Wang, You-Nian

2011-11-01

239

2D full wave modeling for a synthetic Doppler backscattering diagnostica)

NASA Astrophysics Data System (ADS)

Doppler backscattering (DBS) is a plasma diagnostic used in tokamaks and other magnetic confinement devices to measure the fluctuation level of intermediate wavenumber (k??s ˜ 1) density fluctuations and the lab frame propagation velocity of turbulence. Here, a synthetic DBS diagnostic is described, which has been used for comparisons between measurements in the DIII-D tokamak and predictions from nonlinear gyrokinetic simulations. To estimate the wavenumber range to which a Gaussian beam would be sensitive, a ray tracing code and a 2D finite difference, time domain full wave code are used. Experimental density profiles and magnetic geometry are used along with the experimental antenna and beam characteristics. An example of the effect of the synthetic diagnostic on the output of a nonlinear gyrokinetic simulation is presented.

Hillesheim, J. C.; Holland, C.; Schmitz, L.; Kubota, S.; Rhodes, T. L.; Carter, T. A.

2012-10-01

240

Resistivity of dilute 2D electrons in an undoped GaAs heterostructure.

We report resistivity measurements from 0.03 to 10 K in a dilute high mobility 2D electron system. Using an undoped GaAs/AlGaAs heterojunction in a gated field-effect transistor geometry, a wide range of densities, 0.16 x 10(10) to 7.5 x 10(10) cm(-2), are explored. For high densities, the results are quantitatively shown to be due to scattering by acoustic phonons and impurities. In an intermediate range of densities, a peak in the resistivity is observed for temperatures below 1 K. This nonmonotonic resistivity can be understood by considering the known scattering mechanisms of phonons, bulk, and interface ionized impurities. Still lower densities appear insulating to the lowest temperature measured. PMID:12633388

Lilly, M P; Reno, J L; Simmons, J A; Spielman, I B; Eisenstein, J P; Pfeiffer, L N; West, K W; Hwang, E H; Das Sarma, S

2003-02-01

241

Jet theoretical Yang-Mills energy in the geometric dynamics of 2D-monolayer

Langmuir-Blodgett films (LB-films) consist from few LB-monolayers which are high structured nanomaterials that are very promising materials for applications. We use a geometrical approach to describe structurization into LB-monolayers. Consequently, we develop on the 1-jet space J^1([0,\\infty),R^2) the single-time Lagrange geometry (in the sense of distinguished (d-) connection, d-torsions and an abstract anisotropic electromagnetic-like d-field) for the Lagrangian governing the 2D-motion of a particle of monolayer. One assumed that an expansion near singular points for the constructed geometrical Lagrangian theory describe phase transitions to LB-monolayer. Trajectories of particles in a field of the electrocapillarity forces of monolayer have been calculated in a resonant approximation utilizing some Jacobi equations. A jet geometrical Yang-Mills energy is introduced and some physical interpretations are given.

M. Neagu; N. G. Krylova; H. V. Grushevskaya

2012-08-05

242

Toward an Efficient Icing CFD Process Using an Interactive Software Toolkit: Smagglce 2D

NASA Technical Reports Server (NTRS)

Two-dimensional CID analysis for iced airfoils can be a labor-intensive task. The software toolkit SmaggIce 2D is being developed to help streamline the CID process and provide the unique features needed for icing. When complete, it will include a combination of partially automated and fully interactive tools for all aspects of the tasks leading up to the flow analysis: geometry preparation, domain decomposition. block boundary demoralization. gridding, and linking with a flow solver. It also includes tools to perform ice shape characterization, an important aid in determining the relationship between ice characteristics and their effects on aerodynamic performance. Completed tools, work-in-progress, and planned features of the software toolkit are presented here.

Vickerman, Mary B.; Choo, Yung K.; Schilling, Herbert W.; Baez, Marivell; Braun, Donald C.; Cotton, Barbara J.

2001-01-01

243

NASA Astrophysics Data System (ADS)

In this paper we solve the Navier Stokes' equation using finite difference method, on a simulated porous rock structure in 2-D, to study the velocity distribution of fluid flowing through it under a constant pressure gradient. A reactive solute carried through the fluid is allowed to interact with the minerals in the rock. Depending on the rock composition, both dissolution and precipitation reactions may occur. However precipitation occurs only through the cations that are released in the solution due to dissolution. These combined dissolution-precipitation reactions change the porosity, permeability and pore geometry of the sedimentary rock. We study the temporal changes of these properties as functions of Peclet number, concentration of the reactive solute and ratio of Damkholer numbers of dissolution to precipitation. The final flow property is decided by a combination of these parameters.

Sadhukhan, S.; Gouze, P.; Dutta, T.

2014-11-01

244

The transition matrix method for a 2D eddy current interaction problem

NASA Astrophysics Data System (ADS)

A 2D model of the eddy current interaction problem that consists of an inhomogeneity in a conductive half space is presented. The applied analytical method of solution is the transition (T) matrix method. This involves use of the free space Green's function to generate a system of boundary integral relations. In this way, it is easy to identify the contributions to the total solution from each different scattering surface. The different parts are separated also in the computation of the impedance. This leads to low cost simulations in terms of computation time and qualify the method to be used to obtain probability of detection (POD) curves. The T matrix method is a building block method and the possibility to extend the geometry with several inhomogeneities and extra layers will be discussed. The model is compared with a Finite Element (FE) model and numerical examples for the case with a cylindrical inhomogeneity are given.

Larsson, Lars; Rosell, Anders

2012-05-01

245

2D full wave modeling for a synthetic Doppler backscattering diagnostic

Doppler backscattering (DBS) is a plasma diagnostic used in tokamaks and other magnetic confinement devices to measure the fluctuation level of intermediate wavenumber (k{sub {theta}}{rho}{sub s}{approx} 1) density fluctuations and the lab frame propagation velocity of turbulence. Here, a synthetic DBS diagnostic is described, which has been used for comparisons between measurements in the DIII-D tokamak and predictions from nonlinear gyrokinetic simulations. To estimate the wavenumber range to which a Gaussian beam would be sensitive, a ray tracing code and a 2D finite difference, time domain full wave code are used. Experimental density profiles and magnetic geometry are used along with the experimental antenna and beam characteristics. An example of the effect of the synthetic diagnostic on the output of a nonlinear gyrokinetic simulation is presented.

Hillesheim, J. C.; Schmitz, L.; Kubota, S.; Rhodes, T. L.; Carter, T. A. [Department of Physics and Astronomy, University of California, Los Angeles, California 90095 (United States); Holland, C. [University of California, San Diego, La Jolla, California 92093 (United States)

2012-10-15

246

Study of the mechanical behavior of a 2-D carbon-carbon composite

NASA Technical Reports Server (NTRS)

The out-of-plane fracture of a 2-D carbon-carbon composite was observed and characterized to gain an understanding of the factors influencing the stress distribution in such a laminate. Finite element analyses of a two-ply carbon-carbon composite under in-plane, out-of-plane, and thermal loading were performed. Under in-plane loading all components of stress were strong functions of geometry. Additionally, large thermal stresses were predicted. Out-of-plane tensile tests revealed that failure was interlaminar, and that cracks propagated along the fiber-matrix interface. An elasticity solution was utilized to analyze an orthotropic fiber in an isotropic matrix under uniform thermal load. The analysis reveals that the stress distributions in a transversely orthotropic fiber are radically different than those predicted assuming the fiber to be transversely isotropic.

Avery, W. B.; Herakovich, C. T.

1987-01-01

247

An Integrative Model of Excitation Driven Fluid Flow in a 2D Uterine Channel

NASA Astrophysics Data System (ADS)

We present a model of intra-uterine fluid flow in a sagittal cross-section of the uterus by inducing peristalsis in a 2D channel. This is an integrative multiscale computational model that takes as input fluid viscosity, passive tissue properties of the uterine channel and a prescribed wave of membrane depolarization. This voltage pulse is coupled to a model of calcium dynamics inside a uterine smooth muscle cell, which in turn drives a kinetic model of myosin phosphorylation governing contractile muscle forces. Using the immersed boundary method, these muscle forces are communicated to a fluid domain to simulate the contractions which occur in a human uterus. An analysis of the effects of model parameters on the flow properties and emergent geometry of the peristaltic channel will be presented.

Maggio, Charles; Fauci, Lisa; Chrispell, John

2009-11-01

248

Accelerated Acquisition of 2D NMR Spectra using Iterative Projections

NASA Astrophysics Data System (ADS)

Typically, in 2D NMR (or 2D MRI), only one ``row'' of the time-dependent (or k-dependent) signal is sampled N times per ˜T1 (spin-lattice relaxation time). Thus, filling a 2D Cartesian grid of M xN data points requires M additional experiments, for a total spectral acquisition time Tacq M xT1. Measuring fewer ``rows'' than required for Fourier reconstruction decreases Tacq, but this results in a low-quality spectrum (unless more complicated, computationally slower reconstruction techniques are used). Here, we show that a new approach to this problem, using iterative projections, can work on actual 2D NMR data. This approach is built upon the Fast Fourier Transform, so it can handle large data sets (2D, 3D, 4D). Moreover, this approach is expected to work even better in higher dimensions, yielding greater speed ups. Finally, we will discuss how the accelerated acquisition may also improve signal-to-noise and frequency resolution.

Barrett, Sean; Sethna, Zachary; Frey, Merideth; Loria, Patrick

2013-03-01

249

Differentiation of C2D macrophage cells after adoptive transfer.

C2D macrophage cells protect immunocompromised mice from experimentally induced pneumonias after intraperitoneal (i.p.) adoptive transfer. These macrophage cells are immature and display minimal activity in vitro. Therefore, we wanted to understand how adoptive transfer affected these cells. We believe that the in vivo environment affects the phenotypic and functional characteristics of macrophages that help maintain the physiological integrity of the host. To test this hypothesis, we characterized the trafficking patterns and cellular changes of the established macrophage C2D cell line after adoptive transfer. We examined phenotypic changes of the C2D macrophage cells in vivo with and without stimulation with gamma interferon (IFN-gamma). After in vivo i.p. adoptive transfer, C2D macrophage cells trafficked to the lungs, spleen, lymph nodes, and bone marrow of recipient mice. The cells were detected for as long as 2 months, and the cells expressed increased levels of CD11b, c-fms, and F4/80 on their surface, becoming more differentiated macrophages compared to cells maintained in vitro. Upon in vivo stimulation with IFN-gamma, c-fms levels decreased while Gr-1 levels increased compared to in vivo, unstimulated, phosphate-buffered saline-injected controls. These responses were independent of the genetic backgrounds of the recipient mice. These data support the hypothesis and indicate that C2D macrophage cells respond to in vivo signals that are absent during in vitro culture. PMID:18094115

Potts, Betsey E; Hart, Marcia L; Snyder, Laura L; Boyle, Dan; Mosier, Derek A; Chapes, Stephen K

2008-02-01

250

Ultrafast 2D NMR: An Emerging Tool in Analytical Spectroscopy

NASA Astrophysics Data System (ADS)

Two-dimensional nuclear magnetic resonance (2D NMR) spectroscopy is widely used in chemical and biochemical analyses. Multidimensional NMR is also witnessing increased use in quantitative and metabolic screening applications. Conventional 2D NMR experiments, however, are affected by inherently long acquisition durations, arising from their need to sample the frequencies involved along their indirect domains in an incremented, scan-by-scan nature. A decade ago, a so-called ultrafast (UF) approach was proposed, capable of delivering arbitrary 2D NMR spectra involving any kind of homo- or heteronuclear correlation, in a single scan. During the intervening years, the performance of this subsecond 2D NMR methodology has been greatly improved, and UF 2D NMR is rapidly becoming a powerful analytical tool experiencing an expanded scope of applications. This review summarizes the principles and main developments that have contributed to the success of this approach and focuses on applications that have been recently demonstrated in various areas of analytical chemistry—from the real-time monitoring of chemical and biochemical processes, to extensions in hyphenated techniques and in quantitative applications.

Giraudeau, Patrick; Frydman, Lucio

2014-06-01

251

Tryptamine: a possible endogenous substrate for CYP2D6.

The fact that CYP2D6 is not only expressed in liver but also in brain and the clinical association of this cytochrome with Parkinson's disease suggests the possibility of existence of some endogenous substrate, and among these perhaps one or more neurotransmitters could be metabolized by CYP2D6. In this study we explored such a possibility by studying the modulation of CYP2D6 activity by several neurotransmitters. Our findings confirm the occurrence of a competitive inhibition of dextromethorphan O-demethylation in the presence of tryptamine, with a Ki value of 44.6 microM. Tryptamine was metabolized in human liver microsomes by an enzyme activity with a K(m) of 3.6 +/- 0.9 microM. Such activity is NADPH dependent and is inhibited by quinidine and CYP2D6-specific substrates. The product of the reaction is tryptophol. These results suggest that tryptamine may be an endogenous substrate of CYP2D6. PMID:9170145

Martínez, C; Agúndez, J A; Gervasini, G; Martín, R; Benítez, J

1997-04-01

252

Sparse radar imaging using 2D compressed sensing

NASA Astrophysics Data System (ADS)

Radar imaging is an ill-posed linear inverse problem and compressed sensing (CS) has been proved to have tremendous potential in this field. This paper surveys the theory of radar imaging and a conclusion is drawn that the processing of ISAR imaging can be denoted mathematically as a problem of 2D sparse decomposition. Based on CS, we propose a novel measuring strategy for ISAR imaging radar and utilize random sub-sampling in both range and azimuth dimensions, which will reduce the amount of sampling data tremendously. In order to handle 2D reconstructing problem, the ordinary solution is converting the 2D problem into 1D by Kronecker product, which will increase the size of dictionary and computational cost sharply. In this paper, we introduce the 2D-SL0 algorithm into the reconstruction of imaging. It is proved that 2D-SL0 can achieve equivalent result as other 1D reconstructing methods, but the computational complexity and memory usage is reduced significantly. Moreover, we will state the results of simulating experiments and prove the effectiveness and feasibility of our method.

Hou, Qingkai; Liu, Yang; Chen, Zengping; Su, Shaoying

2014-10-01

253

ARC2D - EFFICIENT SOLUTION METHODS FOR THE NAVIER-STOKES EQUATIONS (CRAY VERSION)

NASA Technical Reports Server (NTRS)

ARC2D is a computational fluid dynamics program developed at the NASA Ames Research Center specifically for airfoil computations. The program uses implicit finite-difference techniques to solve two-dimensional Euler equations and thin layer Navier-Stokes equations. It is based on the Beam and Warming implicit approximate factorization algorithm in generalized coordinates. The methods are either time accurate or accelerated non-time accurate steady state schemes. The evolution of the solution through time is physically realistic; good solution accuracy is dependent on mesh spacing and boundary conditions. The mathematical development of ARC2D begins with the strong conservation law form of the two-dimensional Navier-Stokes equations in Cartesian coordinates, which admits shock capturing. The Navier-Stokes equations can be transformed from Cartesian coordinates to generalized curvilinear coordinates in a manner that permits one computational code to serve a wide variety of physical geometries and grid systems. ARC2D includes an algebraic mixing length model to approximate the effect of turbulence. In cases of high Reynolds number viscous flows, thin layer approximation can be applied. ARC2D allows for a variety of solutions to stability boundaries, such as those encountered in flows with shocks. The user has considerable flexibility in assigning geometry and developing grid patterns, as well as in assigning boundary conditions. However, the ARC2D model is most appropriate for attached and mildly separated boundary layers; no attempt is made to model wake regions and widely separated flows. The techniques have been successfully used for a variety of inviscid and viscous flowfield calculations. The Cray version of ARC2D is written in FORTRAN 77 for use on Cray series computers and requires approximately 5Mb memory. The program is fully vectorized. The tape includes variations for the COS and UNICOS operating systems. Also included is a sample routine for CONVEX computers to emulate Cray system time calls, which should be easy to modify for other machines as well. The standard distribution media for this version is a 9-track 1600 BPI ASCII Card Image format magnetic tape. The Cray version was developed in 1987. The IBM ES/3090 version is an IBM port of the Cray version. It is written in IBM VS FORTRAN and has the capability of executing in both vector and parallel modes on the MVS/XA operating system and in vector mode on the VM/XA operating system. Various options of the IBM VS FORTRAN compiler provide new features for the ES/3090 version, including 64-bit arithmetic and up to 2 GB of virtual addressability. The IBM ES/3090 version is available only as a 9-track, 1600 BPI IBM IEBCOPY format magnetic tape. The IBM ES/3090 version was developed in 1989. The DEC RISC ULTRIX version is a DEC port of the Cray version. It is written in FORTRAN 77 for RISC-based Digital Equipment platforms. The memory requirement is approximately 7Mb of main memory. It is available in UNIX tar format on TK50 tape cartridge. The port to DEC RISC ULTRIX was done in 1990. COS and UNICOS are trademarks and Cray is a registered trademark of Cray Research, Inc. IBM, ES/3090, VS FORTRAN, MVS/XA, and VM/XA are registered trademarks of International Business Machines. DEC and ULTRIX are registered trademarks of Digital Equipment Corporation.

Pulliam, T. H.

1994-01-01

254

ARC2D - EFFICIENT SOLUTION METHODS FOR THE NAVIER-STOKES EQUATIONS (DEC RISC ULTRIX VERSION)

NASA Technical Reports Server (NTRS)

ARC2D is a computational fluid dynamics program developed at the NASA Ames Research Center specifically for airfoil computations. The program uses implicit finite-difference techniques to solve two-dimensional Euler equations and thin layer Navier-Stokes equations. It is based on the Beam and Warming implicit approximate factorization algorithm in generalized coordinates. The methods are either time accurate or accelerated non-time accurate steady state schemes. The evolution of the solution through time is physically realistic; good solution accuracy is dependent on mesh spacing and boundary conditions. The mathematical development of ARC2D begins with the strong conservation law form of the two-dimensional Navier-Stokes equations in Cartesian coordinates, which admits shock capturing. The Navier-Stokes equations can be transformed from Cartesian coordinates to generalized curvilinear coordinates in a manner that permits one computational code to serve a wide variety of physical geometries and grid systems. ARC2D includes an algebraic mixing length model to approximate the effect of turbulence. In cases of high Reynolds number viscous flows, thin layer approximation can be applied. ARC2D allows for a variety of solutions to stability boundaries, such as those encountered in flows with shocks. The user has considerable flexibility in assigning geometry and developing grid patterns, as well as in assigning boundary conditions. However, the ARC2D model is most appropriate for attached and mildly separated boundary layers; no attempt is made to model wake regions and widely separated flows. The techniques have been successfully used for a variety of inviscid and viscous flowfield calculations. The Cray version of ARC2D is written in FORTRAN 77 for use on Cray series computers and requires approximately 5Mb memory. The program is fully vectorized. The tape includes variations for the COS and UNICOS operating systems. Also included is a sample routine for CONVEX computers to emulate Cray system time calls, which should be easy to modify for other machines as well. The standard distribution media for this version is a 9-track 1600 BPI ASCII Card Image format magnetic tape. The Cray version was developed in 1987. The IBM ES/3090 version is an IBM port of the Cray version. It is written in IBM VS FORTRAN and has the capability of executing in both vector and parallel modes on the MVS/XA operating system and in vector mode on the VM/XA operating system. Various options of the IBM VS FORTRAN compiler provide new features for the ES/3090 version, including 64-bit arithmetic and up to 2 GB of virtual addressability. The IBM ES/3090 version is available only as a 9-track, 1600 BPI IBM IEBCOPY format magnetic tape. The IBM ES/3090 version was developed in 1989. The DEC RISC ULTRIX version is a DEC port of the Cray version. It is written in FORTRAN 77 for RISC-based Digital Equipment platforms. The memory requirement is approximately 7Mb of main memory. It is available in UNIX tar format on TK50 tape cartridge. The port to DEC RISC ULTRIX was done in 1990. COS and UNICOS are trademarks and Cray is a registered trademark of Cray Research, Inc. IBM, ES/3090, VS FORTRAN, MVS/XA, and VM/XA are registered trademarks of International Business Machines. DEC and ULTRIX are registered trademarks of Digital Equipment Corporation.

Biyabani, S. R.

1994-01-01

255

Investigations of flowfields found in typical combustor geometries

NASA Technical Reports Server (NTRS)

Experimental and theoretical research undertaken on 2-D axisymmetric geometries under low speed, nonreacting, turbulent, swirling flow conditions is reported. The flow enters the test section and proceeds into a larger chamber (the expansion ratio D/d = 2) via a sudden or gradual expansion (sidewall angle alpha = 90 and 45 degrees). Inlet swirl vanes are adjustable to a variety of vane angles with values of phi = 0, 38, 45, 60 and 70 degrees being emphasized.

Lilley, D. G.

1982-01-01

256

NASA Astrophysics Data System (ADS)

We apply a reversible-jump Markov chain Monte Carlo method to sample the Bayesian posterior model probability density function of 2-D seafloor resistivity as constrained by marine controlled source electromagnetic data. This density function of earth models conveys information on which parts of the model space are illuminated by the data. Whereas conventional gradient-based inversion approaches require subjective regularization choices to stabilize this highly non-linear and non-unique inverse problem and provide only a single solution with no model uncertainty information, the method we use entirely avoids model regularization. The result of our approach is an ensemble of models that can be visualized and queried to provide meaningful information about the sensitivity of the data to the subsurface, and the level of resolution of model parameters. We represent models in 2-D using a Voronoi cell parametrization. To make the 2-D problem practical, we use a source-receiver common midpoint approximation with 1-D forward modelling. Our algorithm is transdimensional and self-parametrizing where the number of resistivity cells within a 2-D depth section is variable, as are their positions and geometries. Two synthetic studies demonstrate the algorithm's use in the appraisal of a thin, segmented, resistive reservoir which makes for a challenging exploration target. As a demonstration example, we apply our method to survey data collected over the Scarborough gas field on the Northwest Australian shelf.

Ray, Anandaroop; Key, Kerry; Bodin, Thomas; Myer, David; Constable, Steven

2014-12-01

257

Diffusion Limited Aggregation in Continuous 2D Space Model

NSDL National Science Digital Library

The Diffusion Limited Aggregation in Continuous 2D Space Model simulates the formation of a cluster using a random-walk process called "diffusion limited aggregation" (DLA). The cluster formed by this process is an example of a fractal, and the simulation can be extended to calculate and analyze the fractal dimension. The Diffusion Limited Aggregation in Continuous 2D Space Model was developed using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_fmu_DLA_continuous_2D.jar file will run the program if Java is installed. You can modify this simulation if you have EJS installed by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item.

Engelhardt, Larry

2012-01-07

258

New designs of ultrasonic 2D array probes

NASA Astrophysics Data System (ADS)

Phased-Array ultrasonic probes bring efficiency and flexibility for fast and accurate testing of various parts. Inspections using 2D arrays are still very rare because of the high cost of the electronic when the number of channels increases. Several authors have proposed regular and irregular designs to decrease the element density while maintaining the same phased-array capabilities. Designing such complex 2D probes can become a difficult task without the help of dedicated tools. We have introduced in the CIVA software the possibility to define non-conventional 2D-array probes with complex element patterns and arrangements to solve these difficulties. We describe this new tool and present two probes designed with it: One constituted of hexagonal elements and one sparse array.

Reverdy, F.; Calmon, P.; Ithurralde, G.; Dominguez, N.

2013-01-01

259

2D-3D transition of gold cluster anions resolved

NASA Astrophysics Data System (ADS)

Small gold cluster anions Aun- are known for their unusual two-dimensional (2D) structures, giving rise to properties very different from those of bulk gold. Previous experiments and calculations disagree about the number of gold atoms nc where the transition to 3D structures occurs. We combine trapped ion electron diffraction and state of the art electronic structure calculations to resolve this puzzle and establish nc=12 . It is shown that theoretical studies using traditional generalized gradient functionals are heavily biased towards 2D structures. For a correct prediction of the 2D-3D crossover point it is crucial to use density functionals yielding accurate jellium surface energies, such as the Tao-Perdew-Staroverov-Scuseria (TPSS) functional or the Perdew-Burke-Ernzerhof functional modified for solids (PBEsol). Further, spin-orbit effects have to be included, and large, flexible basis sets employed. This combined theoretical-experimental approach is promising for larger gold and other metal clusters.

Johansson, Mikael P.; Lechtken, Anne; Schooss, Detlef; Kappes, Manfred M.; Furche, Filipp

2008-05-01

260

Dispersion analysis and engineering of 2D plasmonic waveguides

NASA Astrophysics Data System (ADS)

A full investigation of the low-order guided modes in a two-dimensional (2D) hollow metallic waveguide is performed. The dispersion characteristics of the 2D hollow metallic waveguides are identified and analyzed. Manipulating the dispersion is proposed by either changing the geometrical shapes from rectangular to trapezoidal waveguide or changing the material of the cladding region to TiN. The dispersion analysis of the 2D plasmonic waveguide using TiN is investigated for the first time. The effect of varying the shape parameters on the cutoff in the modes dispersion is studied. The trapezoidal shape waveguide that causes the most significant shift in the cutoff is selected and detailed dispersion analysis of its guided modes is performed. The effect of changing the plasmonic material on the dispersion curve key characteristics is also identified. Finally, the effect of shifting the cutoff on the enhanced transmission phenomena is investigated.

Mekawey, Hosam; Ismail, Yehea; Swillam, Mohamed A.

2015-01-01

261

Students Discovering Spherical Geometry Using Dynamic Geometry Software

ERIC Educational Resources Information Center

Dynamic geometry software (DGS) such as Cabri and Geometers' Sketchpad has been regularly used worldwide for teaching and learning Euclidean geometry for a long time. The DGS with its inductive nature allows students to learn Euclidean geometry via explorations. However, with respect to non-Euclidean geometries, do we need to introduce them to…

Guven, Bulent; Karatas, Ilhan

2009-01-01

262

Acoustic Receptivity of a Blasius Boundary Layer with 2-D and Oblique Surface Waviness

NASA Technical Reports Server (NTRS)

An experimental investigation was conducted to examine acoustic receptivity and subsequent boundary-layer instability evolution for a Blasius boundary layer formed on a flat plate in the presence of two-dimensional (2-D) and oblique (3-D) surface waviness. The effect of the non-localized surface roughness geometry and acoustic wave amplitude on the receptivity process was explored. The surface roughness had a well defined wavenumber spectrum with fundamental wavenumber k (sub w). A planar downstream traveling acoustic wave was created to temporally excite the flow near the resonance frequency of an unstable eigenmode corresponding to k (sub ts) = k (sub w). The range of acoustic forcing levels, epsilon, and roughness heights, DELTA h, examined resulted in a linear dependence of receptivity coefficients; however, the larger values of the forcing combination epsilon dot DELTA h resulted in subsequent nonlinear development of the Tollmien-Schlichting (T-S) wave. This study provided the first experimental evidence of a marked increase in the receptivity coefficient with increasing obliqueness of the surface waviness in excellent agreement with theory. Detuning of the 2-D and oblique disturbances was investigated by varying the streamwise wall-roughness wavenumber a,, and measuring the T-S response. For the configuration where laminar-to-turbulent breakdown occurred, the breakdown process was found to be dominated by energy at the fundamental and harmonic frequencies, indicative of K-type breakdown.

King, Rudolph A.; Breuer, Kenneth S.

2000-01-01

263

Complex 2D photonic crystals with analogue local symmetry as 12-fold quasicrystals.

We construct fourteen complex periodic two-dimensional (2D) photonic structures with different structural symmetries by arranging the small portions of a 12-fold quasicrystal on square or hexagonal lattices. The corresponding reciprocal lattices confirm that all of them demonstrate the 12-fold-like characteristics due to the analogue short-range arrangements. We then investigate their photonic bandgap properties at different dielectric contrast levels (dielectric rods in air background). Our results suggest that all structures possess analogue transverse magnetic (TM) gaps in both Si and glass photonic crystals due to the similarity of their local geometries. However, the arrangements of the basic elements, total symmetries, and the coupling between the local and the lattice symmetries have greater impact on the glass photonic crystals, which show much larger deviation of gap sizes from different structures. Furthermore, we find that the minimal dielectric contrast to achieve the TM gap in the complex lattices (dielectric-in-air) can be as low as epsilon = 1.44, whereas the inverse structures may open a 2D complete gap in silicon nitride (epsilon = 4.1). PMID:19770885

Cheng, Shih-Chieh; Zhu, Xuelian; Yang, Shu

2009-09-14

264

Dynamics of 2D Dust Clusters with a Perpendicular Magnetic Field

The physics of two-dimensional (2D) dust clusters in an unmagnetized plasma sheath has been understood in dept. However, introduction of a perpendicular magnetic field into the dusty plasma sheath leads to some new effects, such as rotation and compression of dust clusters, whose mechanism is still unclear. It is found that even for a magnetic field as low as the earth magnetic field ({approx_equal}40 {mu}T), clusters rotate as rigid about their centers. It was proposed [U. Konopka, PRE 61, 1890 (2000)] that the ExB-induced ion flow drives the dust clusters into rotation. Simulations [L.-J. Hou, PoP 12, 042104 (2005)] based on the same hypothesis also reproduced the rotation of 2D clusters in a qualitative manner. However, this model cannot fully explain the experimental observations. We present detailed experimental investigations, which show that the rotation of a dust cluster critically depends on the detailed discharge geometry. In particular, the co-rotation of the background neutral gas and its role in driving dust-cluster rotation is proposed as a mechanism to set the dust cluster in rotation.

Greiner, Franko; Carstensen, Jan; Hou Lujing; Piel, Alexander [Institut fuer Experimentelle und Angewandte Physik, Christian-Albrechts Universitaet, Kiel (Germany)

2008-09-07

265

SNARK09 - a software package for reconstruction of 2D images from 1D projections.

The problem of reconstruction of slices and volumes from 1D and 2D projections has arisen in a large number of scientific fields (including computerized tomography, electron microscopy, X-ray microscopy, radiology, radio astronomy and holography). Many different methods (algorithms) have been suggested for its solution. In this paper we present a software package, SNARK09, for reconstruction of 2D images from their 1D projections. In the area of image reconstruction, researchers often desire to compare two or more reconstruction techniques and assess their relative merits. SNARK09 provides a uniform framework to implement algorithms and evaluate their performance. It has been designed to treat both parallel and divergent projection geometries and can either create test data (with or without noise) for use by reconstruction algorithms or use data collected by another software or a physical device. A number of frequently-used classical reconstruction algorithms are incorporated. The package provides a means for easy incorporation of new algorithms for their testing, comparison and evaluation. It comes with tools for statistical analysis of the results and ten worked examples. PMID:23414602

Klukowska, Joanna; Davidi, Ran; Herman, Gabor T

2013-06-01

266

Turbulent flow over a surface-mounted 2-D block: thermal stability effects

NASA Astrophysics Data System (ADS)

Momentum and scalar transport in turbulent boundary-layer flows over complex topography has been of great interest in the atmospheric sciences and wind engineering communities. The physical geometry of the topography, surface characteristics (e.g., roughness and temperature) and atmospheric thermal stability play important roles in momentum and scalar flux distribution. Numerous studies of flow over simplified topography, 2-D or 3-D blocks and sinusoidal hills have been conducted under neutral boundary-layer conditions. However, thermal stability effects are seldom taken into account due to the challenge of performing such laboratory simulations, for instance, wind-tunnel experiments. A limited number of experimental data sets are currently available, which severely hinders understanding of the underlying physics. Such data sets are also in high demand for development of new parameterization of surface fluxes and validation in numerical models such as Large-Eddy Simulation (LES). We present an experimental investigation of neutral and thermally-stratified boundary-layer flows over a surface-mounted 2-D block at the Saint Anthony Falls Laboratory boundary-layer wind tunnel. The 2-D block, with a width to height ratio of 2:1, was fully immersed in the surface layer of the turbulent boundary layer. Thermal stratification conditions were achieved by independently controlling the temperature of both the air flow and the test section floor and block surfaces. Measurements were obtained, using high-resolution PIV, x-wire/cold-wire anemometry and surface heat flux sensors, to quantify the thermal stability effects on the turbulent flow properties, especially the separation/recirculation zone, coherent vortex structures, the subsequent boundary layer recovery and spatial distribution of surface fluxes. This work aims to enhance our understanding of the thermal stability effects on the turbulent boundary-layer flows over complex topography, and provide a reliable database for validating and improving LES modeling.

Zhang, Wei; Markfort, Corey; Porté-Agel, Fernando

2013-04-01

267

Rapid Plateau border size variations expected in three simple experiments on 2D liquid foams.

Up to a global scaling, the geometry of foams squeezed between two solid plates (2D GG foams) essentially depends on two independent parameters: the liquid volume fraction and the degree of squeezing (bubble thickness to diameter ratio). We describe it in two main asymptotic regimes: fully dry floor tiles, where the Plateau border radius is smaller than the distance between the solid plates, and dry pancakes, where it is larger. We predict a rapid variation of the Plateau border radius in one part of the pancake regime, namely when the Plateau border radius is larger than the inter-plate distance but smaller than the geometric mean of that distance and the bubble perimeter. This rapid variation is not related to any topological change in the foam: in all the regimes we consider, the bubbles remain in mutual lateral contact through films located at mid-height between both plates. We provide asymptotic predictions in different types of experiments on such 2D GG foams: when foam is being progressively dried or wetted, when it is being squeezed further or stretched, when it coarsens through film breakage or through inter-bubble gas diffusion. Our analysis is restricted to configurations close to equilibrium, as we do not include stresses resulting from bulk viscous flow or from non-homogeneous surfactant concentrations. We also assume that the inter-plate distance is sufficiently small for gravity to be negligible. The present work does not provide a method for measuring small Plateau border radii experimentally, but it indicates that large (and easily observable) Plateau borders should appear or disappear rather suddenly in some types of experiments with small inter-plate gaps. It also gives expected orders of magnitude that should be helpful for designing experiments on 2D GG foams. PMID:21253804

Gay, C; Rognon, P; Reinelt, D; Molino, F

2011-01-01

268

Noninvasive deep Raman detection with 2D correlation analysis

NASA Astrophysics Data System (ADS)

The detection of poisonous chemicals enclosed in daily necessaries is prerequisite essential for homeland security with the increasing threat of terrorism. For the detection of toxic chemicals, we combined a sensitive deep Raman spectroscopic method with 2D correlation analysis. We obtained the Raman spectra from concealed chemicals employing spatially offset Raman spectroscopy in which incident line-shaped light experiences multiple scatterings before being delivered to inner component and yielding deep Raman signal. Furthermore, we restored the pure Raman spectrum of each component using 2D correlation spectroscopic analysis with chemical inspection. Using this method, we could elucidate subsurface component under thick powder and packed contents in a bottle.

Kim, Hyung Min; Park, Hyo Sun; Cho, Youngho; Jin, Seung Min; Lee, Kang Taek; Jung, Young Mee; Suh, Yung Doug

2014-07-01

269

Nomenclature for human CYP2D6 alleles.

To standardize CYP2D6 allele nomenclature, and to conform with international human gene nomenclature guidelines, an alternative to the current arbitrary system is described. Based on recommendations for human genome nomenclature, we propose that alleles be designated by CYP2D6 followed by an asterisk and a combination of roman letters and arabic numerals distinct for each allele with the number specifying the key mutation and, where appropriate, a letter specifying additional mutations. Criteria for classification as a separate allele and protein nomenclature are also presented. PMID:8807658

Daly, A K; Brockmöller, J; Broly, F; Eichelbaum, M; Evans, W E; Gonzalez, F J; Huang, J D; Idle, J R; Ingelman-Sundberg, M; Ishizaki, T; Jacqz-Aigrain, E; Meyer, U A; Nebert, D W; Steen, V M; Wolf, C R; Zanger, U M

1996-06-01

270

Exact computation of scalar 2D aerial imagery

NASA Astrophysics Data System (ADS)

An exact formulation of the problem of imaging a 2D object through a Koehler illumination system is presented; the accurate simulation of a real layout is then not time- limited but memory-limited. The main idea behind the algorithm is that the boundary of the region that comprise a typical TCC Is made up of circular arcs, and therefore the area - which determines the value of the TCC - should be exactly computable in terms of elementary analytical functions. A change to integration around the boundary leads to an expression with minimal dependence on expensive functions such as arctangents and square roots. Numerical comparisons are made for a simple 2D structure.

Gordon, Ronald L.

2002-07-01

271

2-D wavelet packet spectrum for texture analysis.

This brief derives a 2-D spectrum estimator from some recent results on the statistical properties of wavelet packet coefficients of random processes. It provides an analysis of the bias of this estimator with respect to the wavelet order. This brief also discusses the performance of this wavelet-based estimator, in comparison with the conventional 2-D Fourier-based spectrum estimator on texture analysis and content-based image retrieval. It highlights the effectiveness of the wavelet-based spectrum estimation. PMID:23412622

Atto, Abdourrahmane M; Berthoumieu, Yannick; Bolon, Philippe

2013-06-01

272

CH2D+, the Search for the Holy Grail

NASA Astrophysics Data System (ADS)

CH2D+, the singly deuterated counterpart of CH3+, offers an alternative way to mediate formation of deuterated species at temperatures of several tens of Kelvin, as compared to the release of deuterated species from grains. We report a longstanding observational search for this molecular ion, whose rotational spectroscopy is not yet completely secure. We summarize the main spectroscopic properties of this molecule and discuss the chemical network leading to the formation of CH2D+, with explicit account of the ortho/para forms of H2, H3+, and CH3+. Astrochemical models support the presence of this molecular ion in moderately warm environments at a marginal level.

Roueff, Evelyne; Gerin, Maryvonne; Lis, Dariusz C.; Wootten, Alwyn; Marcelino, Nuria; Cernicharo, Jose; Tercero, Belen

2013-10-01

273

CH2D(+), the search for the holy grail.

CH2D+, the singly deuterated counterpart of CH3(+), offers an alternative way to mediate formation of deuterated species at temperatures of several tens of Kelvin, as compared to the release of deuterated species from grains. We report a longstanding observational search for this molecular ion, whose rotational spectroscopy is not yet completely secure. We summarize the main spectroscopic properties of this molecule and discuss the chemical network leading to the formation of CH2D+, with explicit account of the ortho/para forms of H2, H3(+), and CH3(+). Astrochemical models support the presence of this molecular ion in moderately warm environments at a marginal level. PMID:23627602

Roueff, Evelyne; Gerin, Maryvonne; Lis, Dariusz C; Wootten, Alwyn; Marcelino, Nuria; Cernicharo, Jose; Tercero, Belen

2013-10-01

274

Assessment of 2D resistivity structures using 1D inversions

resistivity forward modeling program developed by Dr. A. Dey and Dr. H. F. Morrison. I would also like to thank Mr. Ted Asche of the University of California for his help as I was learning to use the program. Finally, I would like to thank my friends... IN TWO DIMENSIONS Dey and Morrison's Approach RESlS2D: Details and Testing Susunsary IV. 1D INTERPRETATION OF 2D RESISTIVITY STRUCTURES Methodology Model 1: Vertical Dike Model 2: Normal Fault Model 3: Tabular Prism Model 4: Square Prism Model...

Beard, Les Paul

2012-06-07

275

NASA Astrophysics Data System (ADS)

A collocation spectral domain decomposition method (CSDDM) based on the influence matrix technique is developed to solve radiative transfer problems within a participating medium of 2D partitioned domains. In this numerical approach, the spatial domains of interest are decomposed into rectangular sub-domains. The radiative transfer equation (RTE) in each sub-domain is angularly discretized by the discrete ordinates method (DOM) with the SRAPN quadrature scheme and then is solved by the CSDDM directly. Three test geometries that include square enclosure and two enclosures with one baffle and one centered obstruction are used to validate the accuracy of the developed method and their numerical results are compared to the data obtained by other researchers. These comparisons indicate that the CSDDM has a good accuracy for all solutions. Therefore this method can be considered as a useful approach for the solution of radiative heat transfer problems in 2D partitioned domains.

Chen, Shang-Shang; Li, Ben-Wen

2014-12-01

276

The paper deals with quantitative phase imaging of two-height-level surface reliefs. The imaging is considered to be a linear system and, consequently, the Fourier transform of the image is the product of the Fourier transform of a 2D function characterizing the surface and a specific 2D coherent transfer function. The Fourier transform of functions specifying periodic surface reliefs is factorized into two functions similar to lattice and structure amplitudes in crystal structure analysis. The approach to the imaging process described in the paper enables us to examine the dependence of the phase image on the surface geometry. Theoretical results are verified experimentally by means of a digital holographic microscope. PMID:20940953

Lovicar, Lud?k; Komrska, Ji?í; Chmelík, Radim

2010-09-27

277

An Introduction to Projective Geometry

NSDL National Science Digital Library

The contents of this paper include: The Projective Plane; Projective Space; Projective Geometry Applied to Computer Vision; Demonstration of Cross Ratio in P^1; and a bibliography. (Euclidean geometry is a subset of projective geometry, and there are two geometries between them: similarity and affine.) Also at http://vision.stanford.edu/~birch/projective/.

Birchfield, Stan

2008-09-19

278

The Bifurcation Approach Hyperbolic Geometry

1 The Bifurcation Approach To Hyperbolic Geometry Abraham A. Ungar Department of Mathematics North of relativity physics gives rise to important isometries in hyperbolic geometry that expose analogies with EuÂ clidean geometry. These, in turn, suggest our bifurcation approach to hyÂ perbolic geometry, according

Ungar, Abraham A.

279

Three-Dimensional Geometry and

Three-Dimensional Geometry and Topology William P. Thurston This book was the ori- gin of a grand spaces. To do this, he had to establish the strong connection of geometry to topology--the study- pression "Thurston-type geometry" has become a commonplace. Three-Dimensional Geometry and Topology had its

Landweber, Laura

280

Geometry, noncommutative algebra and representations

Geometry, noncommutative algebra and representations Iain Gordon http://www.maths.ed.ac.uk/~igordon/ University of Edinburgh 16th December 2006 1 Iain Gordon Geometry, noncommutative algebra and representations #12;2 Iain Gordon Geometry, noncommutative algebra and representations #12;Outline 1 Geometry

Wirosoetisno, Djoko

281

The cytochrome P450 2D6 (CYP2D6) is involved in the metabolism of most antidepressants. Comedication with a potent CYP2D6 inhibitor can convert patients with extensive metabolizer (EM) or ultra-rapid metabolizer (UM) genotypes into poor metabolizer (PM) phenotypes. Since comedication is frequent in depressed patients treated with antidepressants, we investigated the effect of the CYP2D6 composite phenotype on antidepressant efficacy, taking into account both the CYP2D6 genotype and comedication with CYP2D6 inhibitors. 87 Caucasian in patients with a major depressive episode were prospectively treated with flexible doses of antidepressant monotherapy as well as comedications and genotyped for the major CYP2D6 alleles (CYP2D6*3 rs35742686, *4 rs3892097, *5 del, *6 rs5030655, and *2xN). They were classified for CYP2D6 composite phenotype and assessed for antidepressant response after 4 weeks. In terms of genotypes (g), 6 subjects were UMg, 6 PMg, and 75 EMg. Ten patients were coprescribed a CYP2D6 inhibitor, resulting in the following composite phenotypes (cp): 5 UMcp, 16 PMcp, and 66 EMcp. Whereas none of the CYP2D6 genotypes were significantly associated with antidepressant response, UMcp had a lower antidepressant response than PMcp or EMcp (respectively: 39.0 ± 17.9, 50.0 ± 26.0, and 61.6 ± 23.4, p = 0.02). Despite small sample size, this study suggests that a CYP2D6 composite phenotype, taking into account both genotype and comedications with CYP2D6 inhibitors, could predict CYP2D6 substrate antidepressants response. Thus, to optimize antidepressant response, CYP2D6 genotype could be performed and comedications with CYP2D6 inhibitors should be avoided, when prescribing CYP2D6 substrate antidepressants. PMID:25047911

Gressier, F; Verstuyft, C; Hardy, P; Becquemont, L; Corruble, E

2015-01-01

282

We have recently developed a new and simple way of collecting 2D infrared and visible spectra that utilizes a pulse shaper and a partly collinear beam geometry. 2D IR and Vis spectroscopies are powerful tools for studying molecular structures and their dynamics. They can be used to correlate vibrational or electronic eigenstates, measure energy transfer rates, and quantify the dynamics of lineshapes, for instance, all with femtosecond time-resolution. As a result, they are finding use in systems that exhibit fast dynamics, such as sub-millisecond chemical and biological dynamics, and in hard-to-study environments, such as in membranes. While powerful, these techniques have been difficult to implement because they require a series of femtosecond pulses to be spatially and temporally overlapped with precise time-resolution and interferometric phase stability. However, many of the difficulties associated with implementing 2D spectroscopies are eliminated by using a pulse shaper and a simple beam geometry, which substantially lowers the technical barriers required for researchers to enter this exciting field while simultaneously providing many new capabilities. The aim of this paper is to provide an overview of the methods for collecting 2D spectra so that an outsider considering using 2D spectroscopy in their own research can judge which approach would be most suitable for their research aims. This paper focuses primarily on 2D IR spectroscopy, but also includes our recent work on adapting this technology to collecting 2D Vis spectra. We review work that has already been published as well as cover several topics that we have not reported previously, including phase cycling methods to remove background signals, eliminate unwanted scatter, and shift data collection into the rotating frame. PMID:19290321

Shim, Sang-Hee; Zanni, Martin T.

2010-01-01

283

NASA Astrophysics Data System (ADS)

Emission data from a new geometry of Ionic Liquid Ion Sources using porous materials are presented. Ionic liquids are molten salts at room temperature which have near zero vapour pressure. When used in electrospray thrusters, these sources provide an efficient thrust mechanism and, due to their low vapor pressure, eliminate the need for complex propellant feed systems. By emitting pure ion beams rather than mixed ion/droplet emission, small high efficiency thrusters capable of providing specific impulse levels of several thousand seconds can be realized. The latest developments of these thrusters, using conical emitters micro-fabricated from porous substrates, are presented. Porous substrates provide liquid flow over a wide range of emitted currents, accommodating steady, stable emission of ion beams. Conical type emitters, fabricated on a planar porous substrate are well suited for high density 2-D arrays as they allow for both passive propellant feed through the bulk and simplified grid alignment compared with arrays formed from multiple emitter array substrates. This paper confirms that such conical emitters can provide beam currents of 100's of nA up to several ?A with beams composed of pure ions with no charged droplets detected, as has previously been observed using alternative emitter geometries.

G. Courtney, Daniel; Lozano, Paulo

284

NASA Astrophysics Data System (ADS)

Recently, the application of geometry and conformal mappings to artificial materials (metamaterials) has attracted the attention in various research communities. These materials, characterized by a unique man-made structure, have unusual optical properties, which materials found in nature do not exhibit. By applying the geometry and conformal mappings theory to metamaterial science, it may be possible to realize so-called "Harry Potter cloaking device". Although such a device is still in the science fiction realm, several works have shown that by using such metamaterials it may be possible to control the direction of the electromagnetic field at will. We could then make an object hidden inside of a cloaking device. Here, we will explain how to design invisibility device using differential geometry and conformal mappings.

Ochiai, T.; Nacher, J. C.

2011-09-01

285

Cells are highly complex and orderly machines, with defined shapes and a startling variety of internal organizations. Complex geometry is a feature of both free-living unicellular organisms and cells inside multicellular animals. Where does the geometry of a cell come from? Many of the same questions that arise in developmental biology can also be asked of cells, but in most cases we do not know the answers. How much of cellular organization is dictated by global cell polarity cues as opposed to local interactions between cellular components? Does cellular structure persist across cell generations? What is the relationship between cell geometry and tissue organization? What ensures that intracellular structures are scaled to the overall size of the cell? Cell biology is only now beginning to come to grips with these questions. PMID:21880160

2011-01-01

286

Discrepant Results in a 2-D Marble Collision

ERIC Educational Resources Information Center

Video analysis of 2-D collisions is an excellent way to investigate conservation of linear momentum. The often-desired experimental design goal is to minimize the momentum loss in order to demonstrate the conservation law. An air table with colliding pucks is an ideal medium for this experiment, but such equipment is beyond the budget of many…

Kalajian, Peter

2013-01-01

287

Oil well perforator design using 2D Eulerian code

The purpose of the present study is to obtain a good shaped charge design using a 2D Eulerian code such that the high speed jet of the liner creates a large hole in the well casing and a small hole in the gun pipe. Double-velocity inverse gradients, one at the tip of the liner and another one located near the

Wen Ho Lee

2002-01-01

288

Silver Staining of 2D Electrophoresis Gels Thierry Rabilloud

and 10 times higher than colloidal Coomassie Blue. However, the first silver staining protocols wereSilver Staining of 2D Electrophoresis Gels Thierry Rabilloud CEA-DSV-iRTSV/LCBM and UMR CNRS Head: Silver staining #12;i. Abstract Silver staining is used to detect proteins after electrophoretic

Paris-Sud XI, UniversitÃ© de

289

Studies of 2D Cryocrystals by STM Techniques

Scanning tunneling microscopy (STM) studies of two-dimensional (2D) cryocrystals4He, Kr, Xe) physisorbed on graphite surfaces are presented. Individual helium atoms, usually thought to be invisible with STM, were recently observed on graphite surfaces at a density corresponding to the\\u000a

C. Bauerlet; N. Mori; G. Kurata; Hiroshi Fukuyamat

1998-01-01

290

[Denoising worm artifacts of elastogram using 2-D wavelet shrinkage].

This paper proposes a technique to denoise the worm artifacts of elastogram using 2-D wavelet shrinkage denoising method. Firstly, strain estimate matrix including worm artifacts was decomposed to 3 levels by 2-D discrete wavelet transform with Sym8 wavelet function, and the thresholds were obtained using Birg6-Massart algorithm. Secondly, all the high frequency coefficients on different levels were quantized by using hard threshold and soft threshold function. Finally, the strain estimate matrix was reconstructed by using the 3rd layer low frequency coefficients and other layer quantized high frequency coefficients. The simulation results illustrated that the present technique could efficiently denoise the worm artifacts, enhance the elastogram performance indices, such as elastographic signal-to-noise ratio (SNRe) and elastographic contrast-to-noise ratio (CNRe), and could increase the correlation coefficient between the denoised elastogram and the ideal elastogram. In comparison with 2-D low-pass filtering, it could also obtain the higher elastographic SNRe and CNRe, and have clearer hard lesion edge. In addition, the results demonstrated that the proposed technique could suppress worm artifacts of elastograms for various applied strains. This work showed that the 2-D wavelet shrinkage denoising could efficiently denoise the worm artifacts of elastogram and enhance the performance of elastogram. PMID:21774202

Cui, Shaoguo; Liu, Dongquan

2011-06-01

291

SAR imaging via modern 2-D spectral estimation methods

Discusses the use of modern 2D spectral estimation algorithms for synthetic aperture radar (SAR) imaging. The motivation for applying power spectrum estimation methods to SAR imaging is to improve resolution, remove sidelobe artifacts, and reduce speckle compared to what is possible with conventional Fourier transform SAR imaging techniques. This paper makes two principal contributions to the field of adaptive SAR

Stuart R. Degraaf

1998-01-01

292

Reconstructing 3D Human Pose from 2D Image Landmarks

the configurations spanned in the corpus, ensuring anthropometric plausibility while discouraging impossible that violate anthropometric con- straints such as limb proportions, yet yield a projection in 2D that is plausible. The goal is therefore to develop an activity-independent model while ensuring anthropometric

Sheikh, Yaser Ajmal

293

ENVIRONMENTAL EFFECTS OF DREDGING AND DISPOSAL (E2-D2)

US Army Corps of Engineers public web site for the "Environmental Effects of Dredging and Disposal" ("E2-D2") searchable database of published reports and studies about environmental impacts associated with dredging and disposal operations. Many of the reports and studies are ava...

294

A potential based panel method for 2-D hydrofoils

A potential based panel method for the hydrodynamic analysis of 2-D hydrofoils moving beneath the free surface with constant speed without considering cavitation is described. By applying Green's theorem and the Green function method, an integral equation for the perturbation velocity potential is obtained under the potential flow theory. Dirichlet type boundary condition is used instead of Neumann type boundary

Sakir Bal

1998-01-01

295

Face Recognition Using 2D and 3D Facial Data

Results are presented for the largest experimental study to date that investigates the comparison and combination of 2D and 3D face recognition. To our knowledge, this is also the only such study to incorporate signicant time lapse be- tween gallery and probe image acquisition, and to look at the effect of depth resolution. Recognition results are ob- tained in (1)

Kyong I. Chang; Kevin W. Bowyer; Patrick J. Flynn

2003-01-01

296

ccsd00001043 2D ground motion at a soft viscoelastic

ccsdÂ00001043 (version 1) : 20 Jan 2004 2D ground motion at a soft viscoelastic layer City-like site, radiating a SH pulse of 4s duration, produces substan- tial ground motion during 200s extent, shear-horizontal motion): 1) coupling to Love modes is all the weaker the farther the seismic

297

"Stem Cell Migration on 2D Biomaterials Platforms" Tyler Vlass

, Chemical Engineering The research project I will be working on this summer deals with stem cell motility. I will be building off of research done by the Peyton Lab. When testing stem cell movement on 3D scaffolds"Stem Cell Migration on 2D Biomaterials Platforms" Tyler Vlass Faculty Mentor: Dr. Shelly Peyton

Mountziaris, T. J.

298

3D Face Reconstruction from 2D Images

This paper surveys the topic of 3D face reconstruction using 2D images from a computer science perspective. Various approaches have been proposed as solutions for this problem but most have their limitations and drawbacks. Shape from shading, shape from silhouettes, shape from motion and analysis by synthesis using morphable models are currently regarded as the main methods of attaining the

W. N. Widanagamaachchi; A. T. Dharmaratne

2008-01-01

299

Polynomial transform computation of the 2-D DCT

A 2-D DCT (discrete cosine transform) algorithm based on a direct polynomial approach is presented. The resulting algorithm reduces the number of both multiplications and additions compared to previous algorithms. It is shown that, although being mathematically involved, it possesses a clean, butterfly-based structure. Tables comparing the number of operations are provided, as well as flowgraphs

P. Duhamel; C. Guillemot

1990-01-01

300

Protein Folding in 3-d and 2-d

NSDL National Science Digital Library

A workshop on protein folding. PowerPoint presentation of the major issues in protein folding. Demonstration of 3-d protein structure by looking at the structure of lysozyme and searching for ionic bonds between side chains. 2-d simulation of protein folding called the "Protein Investigator" which allows the user to enter amino acid sequences which are then folded in 2 dimensions.

Brian White (University of Massachusetts;)

2006-06-18

301

2D signature for detection and identification of drugs

NASA Astrophysics Data System (ADS)

The method of spectral dynamics analysis (SDA-method) is used for obtaining the2D THz signature of drugs. This signature is used for the detection and identification of drugs with similar Fourier spectra by transmitted THz signal. We discuss the efficiency of SDA method for the identification problem of pure methamphetamine (MA), methylenedioxyamphetamine (MDA), 3, 4-methylenedioxymethamphetamine (MDMA) and Ketamine.

Trofimov, Vyacheslav A.; Varentsova, Svetlana A.; Shen, Jingling; Zhang, Cunlin; Zhou, Qingli; Shi, Yulei

2011-06-01

302

Recovering 3D tumor locations from 2D bioluminescence images

structure with detailed anatomical structure extracted from high-resolution microCT on a single platform. We imaging modality to BLI is the microCT imaging, which can be used in one session to provide the high extracted from microCT anatomical images. There is a need for 3D reconstruction because 2D BLI images do

Huang, Xiaolei

303

, Vol. 99, No. 4, pp. 590~606 (2011) [7] R. Fabbri, L. D. F. Costa, J. C. Torelli, and O. M. Bruno, 2D] L. Zhang and W. J. Tam, Stereoscopic Image Generation Based on Depth Images for 3D TV, IEEE, Stereoscopic 3D Copy & Paste, ACM Transactions on Graphics, 29(6), p. 147 (2010) [5] V. D. Silva, A. Fernando

Lee, In-Kwon

304

2D Transformation Optics using Anisotropic Transmission-Line Metamaterials

2D Transformation Optics using Anisotropic Transmission-Line Metamaterials Michael Zedler *, George-dimensional metamaterial unit cell which synthesizes equivalent material parameters needed for 'transformation optics', as introduced in [1]. The proposed metamaterial consists of a grid of reactively loaded transmission

Eleftheriades, George V.

305

The 2-D Leap-Frog: Integrability, Noise, and Digitization

The 2-D Leap-Frog: Integrability, Noise, and Digitization Lyle Noakes a and Ryszard Kozera b and Software Engineering b , 35 Stirling Highway, Crawley WA 6009, Australia Summary. The 1-D Leap-Frog paper ? we adapt Leap- Frog to solve an optimization problem in computer vision. The vision problem

Kozera, Ryszard

306

Topology-preserving rigid transformation of 2D digital images

1 Topology-preserving rigid transformation of 2D digital images Phuc Ngo, Nicolas Passat, Yukiko first give some conditions under which Phuc Ngo, Yukiko Kenmochi and Hugues Talbot are with the ESIEE- Paris and the UniversitÂ´e Paris-Est, LIGM UMR CNRS 8049, Paris, France ({h.ngo

Boyer, Edmond

307

The methods and techniques of solar 2D spectral observations

This paper is chiefly devoted to the principles, instrumentation, technology and methods of data analysis of the 2D solar spectroscopy, and a few examples of the observational results with instruments of various kinds are described. Moreover, the deficiencies of the work at the present stage and the prospect of future developments are also pointed out.

Shihui Ye

1997-01-01

308

Secondary order inside 2D crystals of Janus colloidal spheres

Colloidal particles are known to crystallize into hexagonal packing in 2D. When particles are made to be hydrophilic on one side and hydrophobic on the other, a secondary orientation order emerges, with the striking appearance of stripe structures. Factors that determine the crystal structure are investigated, including ionic strength, volume fraction, and Janus balance. Statistical thermodynamic analysis and computer simulations

Jing Yan; Shan Jiang; Stephen Anthony; Qian Chen; Steve Granick

2010-01-01

309

Improving 2D mesh image segmentation with Markovian Random Fields

Traditional mesh segmentation methods normally oper- ate on geometrical models with no image information. On the other hand, 2D image-based mesh generation and seg- mentation counterparts, such as Imesh (6) perform the task by following a set of well defined rules derived from the ge- ometry of the triangles, but with no statistical information of the mesh elements. This paper

Alex Jesus Cuadros-vargas; Leandro C. Gerhardinger; Mario De Castro; João Batista Neto; Luis Gustavo Nonato

2006-01-01

310

2D and 3D Elasticity Imaging Using Freehand Ultrasound

2D and 3D Elasticity Imaging Using Freehand Ultrasound Joel Edward Lindop Pembroke College March. #12;i Summary Medical imaging is vital to modern clinical practice, enabling clinicians to examine to mechanical properties (e.g., stiffness) to which conventional forms of ultrasound, X-ray and magnetic

Drummond, Tom

311

Refraction of surface acoustic waves through 2D phononic crystals

NASA Astrophysics Data System (ADS)

We report on the first experimental evidence of negative refraction of surface acoustic waves, through a prism-shaped 2D phononic crystal having a solid matrix. The sample is constituted by a periodic array of air holes drilled in a Si substrate. The experiments are performed using a laser-ultrasonic technique.

Pierre, J.; Bonello, B.; Boyko, O.; Belliard, L.

2010-03-01

312

Validation and testing of the VAM2D computer code

This document describes two modeling studies conducted by HydroGeoLogic, Inc. for the US NRC under contract no. NRC-04089-090, entitled, Validation and Testing of the VAM2D Computer Code.'' VAM2D is a two-dimensional, variably saturated flow and transport code, with applications for performance assessment of nuclear waste disposal. The computer code itself is documented in a separate NUREG document (NUREG/CR-5352, 1989). The studies presented in this report involve application of the VAM2D code to two diverse subsurface modeling problems. The first one involves modeling of infiltration and redistribution of water and solutes in an initially dry, heterogeneous field soil. This application involves detailed modeling over a relatively short, 9-month time period. The second problem pertains to the application of VAM2D to the modeling of a waste disposal facility in a fractured clay, over much larger space and time scales and with particular emphasis on the applicability and reliability of using equivalent porous medium approach for simulating flow and transport in fractured geologic media. Reflecting the separate and distinct nature of the two problems studied, this report is organized in two separate parts. 61 refs., 31 figs., 9 tabs.

Kool, J.B.; Wu, Y.S. (HydroGeoLogic, Inc., Herndon, VA (United States))

1991-10-01

313

Probabilistic methods applied to 2D electromagnetic numerical dosimetry

Probabilistic methods applied to 2D electromagnetic numerical dosimetry D. Voyer F. Musy L. Nicolas R. Perrussel Abstract Purpose Probabilistic approaches are performed on electromagnetic numeri- cal are required applying these methods while the Monte Carlo method uses 10 000 samples for a comparable accuracy

Paris-Sud XI, UniversitÃ© de

314

Cytochrome P450-2D6 Screening Among Elderly Using Antidepressants (CYSCE)

Depression; Depressive Disorder; Poor Metabolizer Due to Cytochrome P450 CYP2D6 Variant; Intermediate Metabolizer Due to Cytochrome P450 CYP2D6 Variant; Ultrarapid Metabolizer Due to Cytochrome P450 CYP2D6 Variant

2015-01-06

315

De mme, pour A == 23r, Z~ .---

4~. SPECTRES D'ABSORPTION ET D'Ã?MISSION L DU DYSPROSIUM Par GILBERT BARRÃ?RE. AttachÃ© de Recherches discontinuitÃ©s d'absorption L du dysprosium sont mesurÃ©es et Ã©tudiÃ©es avec les structures qui les accompagnent valeurs suivantes pour les longueurs d'onde des discontinuitÃ©s du dysprosium : On voit qu'une rÃ©vision de

Paris-Sud XI, UniversitÃ© de

316

The aim of this paper is to determine electric and physical properties by 2D modelling of glow discharge low pressure in continuous regime maintained by term constant source. This electric discharge is confined in reactor plan-parallel geometry. This reactor is filled by Argon monatomic gas. Our continuum model the order two is composed the first three moments the Boltzmann's equations coupled with Poisson's equation by self consistent method. These transport equations are discretized by the finite volumes method. The equations system is resolved by a new technique, it is about the N-BEE explicit scheme using the time splitting method.

Kraloua, B.; Hennad, A. [Universite des Sciences et de la Technologie d'Oran Mohamed Boudiaf Faculte de Genie Electrique, Departement d'Electrotechnique Laboratoire de Modelisation de Systemes Electrotechniques et Systemes Experts (LMSE) BP. 1505 EL M'Naouar, 31000 Oran (Algeria)

2008-09-23

317

Flood hazard assessment using 1D and 2D approaches

NASA Astrophysics Data System (ADS)

The EU flood risk Directive (Directive 2007/60/EC) prescribes risk assessment and mapping to develop flood risk management plans. Flood hazard mapping may be carried out with mathematical models able to determine flood-prone areas once realistic conditions (in terms of discharge or water levels) are imposed at the boundaries of the case study. The deterministic models are mainly based on shallow water equations expressed in their 1D or 2D formulation. The 1D approach is widely used, especially in technical studies, due to its relative simplicity, its computational efficiency and also because it requires topographical data not as expensive as the ones needed by 2D models. Even if in a great number of practical situations, such as modeling in-channel flows and not too wide floodplains, the 1D approach may provide results close to the prediction of a more sophisticated 2D model, it must be pointed out that the correct use of a 1D model in practical situations is more complex than it may seem. The main issues to be correctly modeled in a 1D approach are the definition of hydraulic structures such as bridges and buildings interacting with the flow and the treatment of the tributaries. Clearly all these aspects have to be taken into account also in the 2D modeling, but with fewer difficulties. The purpose of this paper is to show how the above cited issues can be described using a 1D or 2D unsteady flow modeling. In particular the Authors will show the devices that have to be implemented in 1D modeling to get reliable predictions of water levels and discharges comparable to the ones obtained using a 2D model. Attention will be focused on an actual river (Crati river) located in the South of Italy. This case study is quite complicated since it deals with the simulation of channeled flows, overbank flows, interactions with buildings, bridges and tributaries. Accurate techniques, intentionally developed by the Authors to take into account all these peculiarities in 1D and 2D modeling, will be presented, compared and discussed.

Petaccia, Gabriella; Costabile, Pierfranco; Macchione, Francesco; Natale, Luigi

2013-04-01

318

Noncommutative Geometry and Arithmetic

This is an overview of recent results aimed at developing a geometry of noncommutative tori with real multiplication, with the purpose of providing a parallel, for real quadratic fields, of the classical theory of elliptic curves with complex multiplication for imaginary quadratic fields. This talk concentrates on two main aspects: the relation of Stark numbers to the geometry of noncommutative tori with real multiplication, and the shadows of modular forms on the noncommutative boundary of modular curves, that is, the moduli space of noncommutative tori. To appear in Proc. ICM 2010.

Matilde Marcolli

2010-03-18

319

Five dimensional microstate geometries

NASA Astrophysics Data System (ADS)

In this thesis, we discuss the possibility of exploring the statistical mechanics description of a black hole from the point view of supergravity. Specifically, we study five dimensional microstate geometries of a black hole or black ring. At first, we review the method to find the general three-charge BPS supergravity solutions proposed by Bena and Warner. By applying this method, we show the classical merger of a black ring and black hole on [Special characters omitted.] base space in general are irreversible. On the other hand, we review the solutions on ambi-polar Gibbons-Hawking (GH) base which are bubbled geometries. There are many possible microstate geometries among the bubbled geometries. Particularly, we show that a generic blob of GH points that satisfy certain conditions can be either microstate geometry of a black hole or black ring without horizon. Furthermore, using the result of the entropy analysis in classical merger as a guide, we show that one can have a merger of a black-hole blob and a black-ring blob or two black-ring blobs that corresponds to a classical irreversible merger. From the irreversible mergers, we find the scaling solutions and deep microstates which are microstate geometries of a black hole/ring with macroscopic horizon. These solutions have the same AdS throats as classical black holes/rings but instead of having infinite throats, the throat is smoothly capped off at a very large depth with some local structure at the bottom. For solutions that produced from U (1) × U (1) invariant merger, the depth of the throat is limited by flux quantization. The mass gap is related with the depth of this throat and we show the mass gap of these solutions roughly match with the mass gap of the typical conformal-field-theory (CFT) states. Therefore, based on AdS/CFT correspondence, they can be dual geometries of the typical CFT states that contribute to the entropy of a black hole/ring. On the other hand, we show that for the solutions produced from more general merger (without U (1) × U (1) invariance), the throat can be arbitrarily deep. This presents a puzzle from the point view of AdS/CFT correspondence. We propose that this puzzle may be solved by some quantization of the angle or promoting the flux vectors to quantum spins. Finally, we suggest some future directions of further study including the puzzle of arbitrary long AdS throat and a general coarse-graining picture of microstate geometries.

Wang, Chih-Wei

320

NSDL National Science Digital Library

This metasite "collects various areas in which ideas from discrete and computational geometry (meaning mainly low-dimensional Euclidean geometry) meet some real world applications," according to the site's provider, Dr. David Eppstein of the University of California at Irvine. Categories available include Geometric References and Techniques, Design and Manufacturing, Graphics and Visualization, Information Systems, Medicine and Biology, Physical Sciences, Robotics, Other Applications, and Recent Additions. The types of links included are data sets, patents, journal articles, and research pages (note: a few of the links don't work, but overall the site is useful).

Eppstein, David

321

2D/3D Image Registration using Regression Learning

In computer vision and image analysis, image registration between 2D projections and a 3D image that achieves high accuracy and near real-time computation is challenging. In this paper, we propose a novel method that can rapidly detect an object’s 3D rigid motion or deformation from a 2D projection image or a small set thereof. The method is called CLARET (Correction via Limited-Angle Residues in External Beam Therapy) and consists of two stages: registration preceded by shape space and regression learning. In the registration stage, linear operators are used to iteratively estimate the motion/deformation parameters based on the current intensity residue between the target projec-tion(s) and the digitally reconstructed radiograph(s) (DRRs) of the estimated 3D image. The method determines the linear operators via a two-step learning process. First, it builds a low-order parametric model of the image region’s motion/deformation shape space from its prior 3D images. Second, using learning-time samples produced from the 3D images, it formulates the relationships between the model parameters and the co-varying 2D projection intensity residues by multi-scale linear regressions. The calculated multi-scale regression matrices yield the coarse-to-fine linear operators used in estimating the model parameters from the 2D projection intensity residues in the registration. The method’s application to Image-guided Radiation Therapy (IGRT) requires only a few seconds and yields good results in localizing a tumor under rigid motion in the head and neck and under respiratory deformation in the lung, using one treatment-time imaging 2D projection or a small set thereof. PMID:24058278

Chou, Chen-Rui; Frederick, Brandon; Mageras, Gig; Chang, Sha; Pizer, Stephen

2013-01-01

322

Differential Geometry: Circle Packings

Differential Geometry: Circle Packings [CirclePack, Ken Stephenson] [A Circle Packing Algorithm if it preserves oriented angles. That is, the map sends "tiny" circles to circles. Re Re Re ImImIm f(z)=z2.2 f the curve to the unit disk. #12;Conformal Maps Intuition: Since conformal maps send "tiny" circles

Kazhdan, Michael

323

Quantum Entanglement and Geometry

The phenomenon of quantum entanglement is thoroughly investigated, focussing especially on geometrical aspects and on bipartite systems. After introducing the formalism and discussing general aspects, some of the most important separability criteria and entanglement measures are presented. Finally, the geometry of 2x2- and 3x3-dimensional state spaces is analysed and visualised.

Andreas Gabriel

2010-03-19

324

In a one-dimensional lattice, the induced metric (from a noncommutative geometry calculation) breaks translation invariance. This leads to some inconsistencies among different spectator frames, in the observation of the hoppings of a test particle between lattice sites. To resolve the inconsistencies between the different spectator frames, we replace the test particle's bare mass by an effective locally dependent mass. This

E. Atzmon

325

Spacetime and Euclidean geometry

NASA Astrophysics Data System (ADS)

Using only the principle of relativity and Euclidean geometry we show in this pedagogical article that the square of proper time or length in a two-dimensional spacetime diagram is proportional to the Euclidean area of the corresponding causal domain. We use this relation to derive the Minkowski line element by two geometric proofs of the spacetime Pythagoras theorem.

Brill, Dieter; Jacobson, Ted

2006-04-01

326

Noncommutative Geometry for Pedestrians

A short historical review is made of some recent literature in the field of noncommutative geometry, especially the efforts to add a gravitational field to noncommutative models of space-time and to use it as an ultraviolet regulator. An extensive bibliography has been added containing reference to recent review articles as well as to part of the original literature.

J. Madore

1999-06-16

327

Music critics have compared Bach's music to the precision of mathematics. What "mathematics" and what "precision" are the questions for a curious scientist. The purpose of this short note is to suggest that the mathematics is, at least in part, Mandelbrot's fractal geometry and the precision is the deviation from a log-log linear plot. PMID:11607061

Hsü, K J; Hsü, A J

1990-01-01

328

ERIC Educational Resources Information Center

Geoff Giles died suddenly in 2005. He was a highly original thinker in the field of geometry teaching. As early as 1964, when teaching at Strathallen School in Perth, he was writing in "MT27" about constructing tessellations by modifying the sides of triangles and (irregular) quadrilaterals to produce what he called "trisides" and "quadrisides".…

Fielker, David

2007-01-01

329

Sliding vane geometry turbines

Various systems and methods are described for a variable geometry turbine. In one example, a turbine nozzle comprises a central axis and a nozzle vane. The nozzle vane includes a stationary vane and a sliding vane. The sliding vane is positioned to slide in a direction substantially tangent to an inner circumference of the turbine nozzle and in contact with the stationary vane.

Sun, Harold Huimin; Zhang, Jizhong; Hu, Liangjun; Hanna, Dave R

2014-12-30

330

The tutor for doing proofs in high school geometry consists of a cot of ideal and buggy rules (IRR), a tutor, and an interface. The IBR is responsible for ehiuertly computing matcher, to all the correct and incorrect rules The interface is responsible for interacting with the student and graphically representing the proof. The tutor is responsible for directing the

John R. Anderson; C. Franklin Boyle; Gregg Yost

1985-01-01

331

Computability in Computational Geometry

We promote the concept of object directed computability in computational geometry in order to faithfully generalise the well- established theory of computability for real numbers and real functions. In object directed computability, a geometric object is computable if it is the effective limit of a sequence of finitary objects of the same type as the original object, thus allowing a

Abbas Edalat; Ali Asghar Khanban; André Lieutier

2005-01-01

332

ERIC Educational Resources Information Center

Presented is an activity in which students make models of viruses, which allows them to visualize the shape of these microorganisms. Included are some background on viruses, the biology and geometry of viruses, directions for building viruses, a comparison of cells and viruses, and questions for students. (KR)

Case, Christine L.

1991-01-01

333

Dragon Shapes: Geometry Challenge

NSDL National Science Digital Library

This iOS app requires users to apply their knowledge of geometry to solve Tangram puzzles. The app introduces the challenge through a brief episode and then provides challenges of increasing difficulty throughout level 1. There are fourteen free puzzles in all, with additional puzzles available through an in app purchase.

Lighthouse Learning Studios Ltd

2013-10-14

334

Advanced geometries and regimes

We review and discuss different schemes of laser ion acceleration as well as advanced target geometries in connection with the development of the laser-driven proton source for hadron therapy of oncological diseases, which is a part of the ELIMED project.

Bulanov, S. S. [Univeristy of California, Berkeley, CA, 94720 (United States)] [Univeristy of California, Berkeley, CA, 94720 (United States); Bulanov, S. V. [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan)] [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan); Turchetti, G. [Dipartimento di Fisica, Università di Bologna and INFN Sezione di Bologna, Via Irnerio, 46-I-40126 Bologna (Italy)] [Dipartimento di Fisica, Università di Bologna and INFN Sezione di Bologna, Via Irnerio, 46-I-40126 Bologna (Italy); Limpouch, J.; Klimo, O.; Psikal, J. [Institute of Physics of the ASCR, ELI-Beamlines/HiLASE project, Na Slovance 2, 18221 Prague, Czech Republic and Czech Technical University in Prague, FNSPE, Brehova 7, 115 19 Prague (Czech Republic)] [Institute of Physics of the ASCR, ELI-Beamlines/HiLASE project, Na Slovance 2, 18221 Prague, Czech Republic and Czech Technical University in Prague, FNSPE, Brehova 7, 115 19 Prague (Czech Republic); Antici, P. [Dipartimento di Energetica ed INFM, Università di Roma, La Sapienza, 00165 Roma (Italy)] [Dipartimento di Energetica ed INFM, Università di Roma, La Sapienza, 00165 Roma (Italy); Margarone, D.; Korn, G. [Institute of Physics of the ASCR, ELI-Beamlines/HiLASE project, Na Slovance 2, 18221 Prague (Czech Republic)] [Institute of Physics of the ASCR, ELI-Beamlines/HiLASE project, Na Slovance 2, 18221 Prague (Czech Republic)

2013-07-26

335

Substrates of a major drug-metabolizing enzyme CYP2D6 display increased elimination during pregnancy, but the underlying mechanisms are unknown in part due to a lack of experimental models. Here, we introduce CYP2D6-humanized (Tg-CYP2D6) mice as an animal model where hepatic CYP2D6 expression is increased during pregnancy. In the mouse livers, expression of a known positive regulator of CYP2D6, hepatocyte nuclear factor 4? (HNF4?), did not change during pregnancy. However, HNF4? recruitment to CYP2D6 promoter increased at term pregnancy, accompanied by repressed expression of small heterodimer partner (SHP). In HepG2 cells, SHP repressed HNF4? transactivation of CYP2D6 promoter. In transgenic (Tg)-CYP2D6 mice, SHP knockdown led to a significant increase in CYP2D6 expression. Retinoic acid, an endogenous compound that induces SHP, exhibited decreased hepatic levels during pregnancy in Tg-CYP2D6 mice. Administration of all-trans-retinoic acid led to a significant decrease in the expression and activity of hepatic CYP2D6 in Tg-CYP2D6 mice. This study provides key insights into mechanisms underlying altered CYP2D6-mediated drug metabolism during pregnancy, laying a foundation for improved drug therapy in pregnant women. PMID:24318876

Koh, Kwi Hye; Pan, Xian; Shen, Hong-Wu; Arnold, Samuel L. M.; Yu, Ai-Ming; Gonzalez, Frank J.; Isoherranen, Nina; Jeong, Hyunyoung

2014-01-01

336

Instantons in 2D U(1) Higgs model and 2D CP(N-1) sigma models

NASA Astrophysics Data System (ADS)

In this thesis I present the results of a study of the topological structures of 2D U(1) Higgs model and 2D CP N-1 sigma models. Both models have been studied using the overlap Dirac operator construction of topological charge density. The overlap operator provides a more incisive probe into the local topological structure of gauge field configurations than the traditional plaquette-based operator. In the 2D U(1) Higgs model, we show that classical instantons with finite sizes violate the negativity of topological charge correlator by giving a positive contribution to the correlator at non-zero separation. We argue that instantons in 2D U(1) Higgs model must be accompanied by large quantum fluctuations in order to solve this contradiction. In 2D CPN-1 sigma models, we observe the anomalous scaling behavior of the topological susceptibility chi t for N ? 3. The divergence of chi t in these models is traced to the presence of small instantons with a radius of order a (= lattice spacing), which are directly observed on the lattice. The observation of these small instantons provides detailed confirmation of Luscher's argument that such short-distance excitations, with quantized topological charge, should be the dominant topological fluctuations in CP1 and CP 2, leading to a divergent topological susceptibility in the continuum limit. For the CPN-1 models with N > 3 the topological susceptibility is observed to scale properly with the mass gap. Another topic presented in this thesis is an implementation of the Zolotarev optimal rational approximation for the overlap Dirac operator. This new implementation has reduced the time complexity of the overlap routine from O(N3 ) to O(N), where N is the total number of sites on the lattice. This opens up a door to more accurate lattice measurements in the future.

Lian, Yaogang

2007-12-01

337

2-D linear motion system. Innovative technology summary report

The US Department of Energy's (DOE's) nuclear facility decontamination and decommissioning (D and D) program requires buildings to be decontaminated, decommissioned, and surveyed for radiological contamination in an expeditious and cost-effective manner. Simultaneously, the health and safety of personnel involved in the D and D activities is of primary concern. D and D workers must perform duties high off the ground, requiring the use of manlifts or scaffolding, often, in radiologically or chemically contaminated areas or in areas with limited access. Survey and decontamination instruments that are used are sometimes heavy or awkward to use, particularly when the worker is operating from a manlift or scaffolding. Finding alternative methods of performing such work on manlifts or scaffolding is important. The 2-D Linear Motion System (2-D LMS), also known as the Wall Walker{trademark}, is designed to remotely position tools and instruments on walls for use in such activities as radiation surveys, decontamination, and painting. Traditional (baseline) methods for operating equipment for these tasks require workers to perform duties on elevated platforms, sometimes several meters above the ground surface and near potential sources of contamination. The Wall Walker 2-D LMS significantly improves health and safety conditions by facilitating remote operation of equipment. The Wall Walker 2-D LMS performed well in a demonstration of its precision, accuracy, maneuverability, payload capacity, and ease of use. Thus, this innovative technology is demonstrated to be a viable alternative to standard methods of performing work on large, high walls, especially those that have potential contamination concerns. The Wall Walker was used to perform a final release radiological survey on over 167 m{sup 2} of walls. In this application, surveying using a traditional (baseline) method that employs an aerial lift for manual access was 64% of the total cost of the improved technology. However, for areas over approximately 600 m{sup 2}, the Wall Walker would cost less than the baseline. Using the Wall Walker 2-D LMS, ALARA exposure and worker safety is improved, and there is potential for increased productivity. This innovative technology performed better than the baseline by providing real-time monitoring of the tool or instrument position. Also, the Wall Walker 2-D LMS can traverse any two-dimensional path at constant speeds of up to 18.3 linear meters per minute (60 linear feet per minute). The survey production rate for the innovative technology was about 0.6 m{sup 2}/min (6 ft{sup 2}/min); the baseline production rate was approximately 0.3 m{sup 2}/min (3 ft{sup 2}/min), using the same surveying instrument and maximum scanning rate.

NONE

1998-11-01

338

Evaluation of imaging geometry for stationary chest tomosynthesis

NASA Astrophysics Data System (ADS)

We have recently demonstrated the feasibility of stationary digital chest tomosynthesis (s-DCT) using a dis- tributed carbon nanotube x-ray source array. The technology has the potential to increase the imaging resolution and speed by eliminating source motion. In addition, the flexibility in the spatial configuration of the individual sources allows new tomosynthesis imaging geometries beyond the linear scanning mode used in the conventional systems. In this paper, we report the preliminary results on the effects of the tomosynthesis imaging geometry on the image quality. The study was performed using a bench-top s-DCT system consisting of a CNT x-ray source array and a flat-panel detector. System MTF and ASF are used as quantitative measurement of the in-plane and in-depth resolution. In this study geometries with the x-ray sources arranged in linear, square, rectangular and circular configurations were investigated using comparable imaging doses. Anthropomorphic chest phantom images were acquired and reconstructed for image quality assessment. It is found that wider angular coverage results in better in-depth resolution, while the angular span has little impact on the in-plane resolution in the linear geometry. 2D source array imaging geometry leads to a more isotropic in-plane resolution, and better in-depth resolution compared to 1D linear imaging geometry with comparable angular coverage.

Shan, Jing; Tucker, Andrew W.; Lee, Yueh Z.; Heath, Michael D.; Wang, Xiaohui; Foos, David; Lu, Jianping; Zhou, Otto

2014-03-01

339

NSDL National Science Digital Library

The Geometry Forum is "An Electronic Community for Lovers of Geometry." An NSF-funded project at Swarthmore College, the Geometry Forum is a great place for geometry and math teachers to locate curriculum ideas, software for mathematics, Internet math projects, and information about professional organizations. The student center offers a problem of the week, project of the month, the Internet geometry hunt, student hangouts on the Internet (where students talk about school and math), and students publications. The Geometry Forum has been re-designed and is attractive, easy to navigate, and very friendly. The site is searchable, a Help Desk is included, and the staff is available for questions.

1997-01-01

340

2-D Magnetohydrodynamic Modeling of A Pulsed Plasma Thruster

NASA Technical Reports Server (NTRS)

Experiments are being performed on the NASA Marshall Space Flight Center (MSFC) MK-1 pulsed plasma thruster. Data produced from the experiments provide an opportunity to further understand the plasma dynamics in these thrusters via detailed computational modeling. The detailed and accurate understanding of the plasma dynamics in these devices holds the key towards extending their capabilities in a number of applications, including their applications as high power (greater than 1 MW) thrusters, and their use for producing high-velocity, uniform plasma jets for experimental purposes. For this study, the 2-D MHD modeling code, MACH2, is used to provide detailed interpretation of the experimental data. At the same time, a 0-D physics model of the plasma initial phase is developed to guide our 2-D modeling studies.

Thio, Y. C. Francis; Cassibry, J. T.; Wu, S. T.; Rodgers, Stephen L. (Technical Monitor)

2002-01-01

341

FPCAS2D user's guide, version 1.0

NASA Astrophysics Data System (ADS)

The FPCAS2D computer code has been developed for aeroelastic stability analysis of bladed disks such as those in fans, compressors, turbines, propellers, or propfans. The aerodynamic analysis used in this code is based on the unsteady two-dimensional full potential equation which is solved for a cascade of blades. The structural analysis is based on a two degree-of-freedom rigid typical section model for each blade. Detailed explanations of the aerodynamic analysis, the numerical algorithms, and the aeroelastic analysis are not given in this report. This guide can be used to assist in the preparation of the input data required by the FPCAS2D code. A complete description of the input data is provided in this report. In addition, four test cases, including inputs and outputs, are provided.

Bakhle, Milind A.

1994-12-01

342

Wave propagation in pantographic 2D lattices with internal discontinuities

In the present paper we consider a 2D pantographic structure composed by two orthogonal families of Euler beams. Pantographic rectangular 'long' waveguides are considered in which imposed boundary displacements can induce the onset of traveling (possibly non-linear) waves. We performed numerical simulations concerning a set of dynamically interesting cases. The system undergoes large rotations which may involve geometrical non-linearities, possibly opening the path to appealing phenomena such as propagation of solitary waves. Boundary conditions dramatically influence the transmission of the considered waves at discontinuity surfaces. The theoretical study of this kind of objects looks critical, as the concept of pantographic 2D sheets seems to have promising possible applications in a number of fields, e.g. acoustic filters, vascular prostheses and aeronautic/aerospace panels.

Madeo, A; Neff, P

2014-01-01

343

Implementation of 2-D DCT based on FPGA

NASA Astrophysics Data System (ADS)

Discrete Cosine Transform (DCT) plays an important role in the image and video compression, and it has been widely used in JPEG, MPEG, H.26x. DCT being implemented by hardware is crucial to improve the speed of image compression. This paper presents a method that 2-D DCT is implemented by FPGA, which is based on the algorithm of row-column decomposition, and the parallel structure is used to achieve high throughput. The design is achieved by top-down design methodology and described with Verilog HDL in RTL level. The hardware of 2-D DCT is implemented by the FPGA EP2C35F672C8 made by ALTERA. The experiment results show that the delay time is as low as 15 ns, and the clock frequency as high as 138.35 MHz, which can satisfy the requirements of the real-time video image compression.

Guo, Bao-Zeng; Niu, Li; Liu, Zhi-Ming

2010-08-01

344

Visualization of 2-D and 3-D Tensor Fields

NASA Technical Reports Server (NTRS)

In previous work we have developed a novel approach to visualizing second order symmetric 2-D tensor fields based on degenerate point analysis. At degenerate points the eigenvalues are either zero or equal to each other, and the hyperstreamlines about these points give rise to trisector or wedge points. These singularities and their connecting hyperstreamlines determine the topology of the tensor field. In this study we are developing new methods for analyzing and displaying 3-D tensor fields. This problem is considerably more difficult than the 2-D one, as the richness of the data set is much larger. Here we report on our progress and a novel method to find, analyze and display 3-D degenerate points. First we discuss the theory, then an application involving a 3-D tensor field, the Boussinesq problem with two forces.

Hesselink, Lambertus

1995-01-01

345

Visualization of 2-D and 3-D Tensor Fields

NASA Technical Reports Server (NTRS)

In previous work we have developed a novel approach to visualizing second order symmetric 2-D tensor fields based on degenerate point analysis. At degenerate points the eigenvalues are either zero or equal to each other, and the hyper-streamlines about these points give rise to tri-sector or wedge points. These singularities and their connecting hyper-streamlines determine the topology of the tensor field. In this study we are developing new methods for analyzing and displaying 3-D tensor fields. This problem is considerably more difficult than the 2-D one, as the richness of the data set is much larger. Here we report on our progress and a novel method to find , analyze and display 3-D degenerate points. First we discuss the theory, then an application involving a 3-D tensor field, the Boussinesq problem with two forces.

Hesselink, Lambertus

1997-01-01

346

Transition to chaos in an open unforced 2D flow

NASA Technical Reports Server (NTRS)

The present numerical study of unsteady, low Reynolds number flow past a 2D airfoil attempts to ascertain the bifurcation sequence leading from simple periodic to complex aperiodic flow with rising Reynolds number, as well as to characterize the degree of chaos present in the aperiodic flow and assess the role of numerics in the modification and control of the observed bifurcation scenario. The ARC2D Navier-Stokes code is used in an unsteady time-accurate mode for most of these computations. The system undergoes a period-doubling bifurcation to chaos as the Reynolds number is increased from 800 to 1600; its chaotic attractors are characterized by estimates of the fractal dimension and partial Liapunov exponent spectra.

Pulliam, Thomas H.; Vastano, John A.

1993-01-01

347

FPCAS2D user's guide, version 1.0

NASA Technical Reports Server (NTRS)

The FPCAS2D computer code has been developed for aeroelastic stability analysis of bladed disks such as those in fans, compressors, turbines, propellers, or propfans. The aerodynamic analysis used in this code is based on the unsteady two-dimensional full potential equation which is solved for a cascade of blades. The structural analysis is based on a two degree-of-freedom rigid typical section model for each blade. Detailed explanations of the aerodynamic analysis, the numerical algorithms, and the aeroelastic analysis are not given in this report. This guide can be used to assist in the preparation of the input data required by the FPCAS2D code. A complete description of the input data is provided in this report. In addition, four test cases, including inputs and outputs, are provided.

Bakhle, Milind A.

1994-01-01

348

Strength design with 2-d triaxial braid textile composites

Textile preforms are currently being considered as a possible means for reducing the cost of advanced fiber composites. This paper presents a methodology for strength design of carbon/epoxy 2-d braid fiber composites under general conditions of biaxial stress loading. A comprehensive investigation into the in-plane strength properties of 2-d braids has been carried out, using tubular specimens of AS4/1895 carbon fiber/epoxy made with the RTM process. The biaxial loadings involved both compression-compression and tension-tension biaxial tests. The results showed that failure under biaxial loading could be based on procedures similar to those developed for laminates, using critical strain values in the axial and braid direction fibers, but with degraded strength properties because of the undulating nature of -the fiber paths. A significant loss of strength was observed in the braid directions.

Smith, L.V.; Swanson, S.R. [Univ. of Utah, Salt Lake City, UT (United States). Dept. of Mechanical Engineering

1994-12-31

349

Electrical Spin Injection into High Mobility 2D Systems.

We report on spin injection into a high mobility 2D electron system confined at an (Al,Ga)As/GaAs interface, using (Ga,Mn)As Esaki diode contacts as spin aligners. We measured a clear nonlocal spin valve signal, which varies nonmonotonically with the applied bias voltage. The magnitude of the signal cannot be described by the standard spin drift-diffusion model, because at maximum this would require the spin polarization of the injected current to be much larger than 100%, which is unphysical. A strong correlation of the spin signal with contact width and electron mean free path suggests that ballistic transport in the 2D region below ferromagnetic contacts should be taken into account to fully describe the results. PMID:25526144

Oltscher, M; Ciorga, M; Utz, M; Schuh, D; Bougeard, D; Weiss, D

2014-12-01

350

Electrical Spin Injection into High Mobility 2D Systems

NASA Astrophysics Data System (ADS)

We report on spin injection into a high mobility 2D electron system confined at an (Al ,Ga )As /GaAs interface, using (Ga,Mn)As Esaki diode contacts as spin aligners. We measured a clear nonlocal spin valve signal, which varies nonmonotonically with the applied bias voltage. The magnitude of the signal cannot be described by the standard spin drift-diffusion model, because at maximum this would require the spin polarization of the injected current to be much larger than 100%, which is unphysical. A strong correlation of the spin signal with contact width and electron mean free path suggests that ballistic transport in the 2D region below ferromagnetic contacts should be taken into account to fully describe the results.

Oltscher, M.; Ciorga, M.; Utz, M.; Schuh, D.; Bougeard, D.; Weiss, D.

2014-12-01

351

Numerical simulation of 2D and 3D compressible flows

NASA Astrophysics Data System (ADS)

The work deals with numerical solutions of 2D inviscid and laminar compressible flows in the GAMM channel and DCA 8% cascade, and of 3D inviscid compressible flows in a 3D modification of the GAMM channel (Swept Wing). The FVM multistage Runge-Kutta method and the Lax-Wendroff scheme (Richtmyer's form) with Jameson's artificial dissipation were applied to obtain the numerical solutions. The results are discussed and compared to other similar results and experiments.

Huml, Jaroslav; Kozel, Karel; P?íhoda, Jaromír

2013-02-01

352

Valley and electric photocurrents in 2D silicon and graphene

We show that the optical excitation of multi-valley systems leads to valley currents which depend on the light polarization. The net electric current, determined by the vector sum of single-valley contributions, vanishes for some peculiar distributions of carriers in the valley and momentum spaces forming a pure valley current. We report on the study of this phenomenon, both experimental and theoretical, for graphene and 2D electron channels on the silicon surface.

Tarasenko, S. A.; Ivchenko, E. L. [Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation); Olbrich, P.; Ganichev, S. D. [Terahertz Center, University of Regensburg, 93040 Regensburg (Germany)

2013-12-04

353

Multicolor symbology for remotely scannable 2D barcodes

NASA Astrophysics Data System (ADS)

There has been much recent interest in mobile systems for augmented reality. However, existing visual tagging solutions are not robust at the low resolutions typical of current camera phones or at the low solid angles needed for "across-the-room" reality augmentation. In this paper, we propose a new 2D barcode symbology that uses multiple colors in order to address these challenges. We present preliminary results, showing the detection of example barcodes in this scheme over a range of angles.

Wissner-Gross, Alexander D.; Sullivan, Timothy M.

2008-03-01

354

NASA High-Speed 2D Photogrammetric Measurement System

NASA Technical Reports Server (NTRS)

The object of this report is to provide users of the NASA high-speed 2D photogrammetric measurement system with procedures required to obtain drop-model trajectory and impact data for full-scale and sub-scale models. This guide focuses on use of the system for vertical drop testing at the NASA Langley Landing and Impact Research (LandIR) Facility.

Dismond, Harriett R.

2012-01-01

355

Growth of 2D heterostructures of graphene/BN

NASA Astrophysics Data System (ADS)

Metal free direct growth of graphene on h-BN using a high temperature (~1550°C) chemical vapor deposition technique was done under Ar environment. Growth temperature, methane partial pressure, hydrogen/methane flow ratio, and growth time were varied and optimized. Raman spectroscopy clearly showed the signature of graphene with G- (~1580cm-1) and 2D-mode (~2700cm-1). The smallest width of G- and 2D-peak was 30 and 55cm-1, respectively, and the Raman I2D/IG ratio varied between 0.7 and 1.8. Raman D-peak (~1350cm-1) shows a strong dependence on growth temperature with the smallest ID/IG value of 0.15 at 1550°C. In the case of long growth, nitrogen and boron doping were detected by x-ray photoelectron spectroscopy with a small Raman D'-peak. A continuous graphene film with the rms roughness (1×1 ?m2 area) of 0.32nm was shown by atomic force microscopy. Early stage of growth revealed circular shaped nucleation islands, the density and heights of which are ~15/?m2 and 1-2 graphene monolayer (ML), respectively. The hydrogen/methane flow ratio was found to be a critical parameter to obtain smooth 2D growth. Growth of h-BN is performed with ammonia borane, hydrogen and Ar. The growth is found to be critically dependent on the conditions of the ammonia boran precursor. Reproducible continuous films of h-BN are reported.

Hwang, Jeonghyun; Calderon, Brian R.; Alsalman, Hussain A.; Kwak, Joon Young; Kim, Moonkyung; Spencer, Michael G.

2014-06-01

356

Reduced complexity blind 2D RAKE receiver for CDMA

We previously presented a blind 2D RAKE receiver for (direct sequence spread spectrum) CDMA that cancels strong multi-user access interference (MAI) and optimally combines multipath. After passing the output of each antenna through a matched filter based on the spreading waveform of the desired user, one estimates the signal plus interference spatio-frequency correlation matrix during that portion of the bit

J. Ramos; M. D. Zoltowski

1996-01-01

357

Submicrometric 2D ratchet effect in magnetic domain wall motion

NASA Astrophysics Data System (ADS)

Strips containing arrays of submicrometric triangular antidots with a 2D square periodicity have been fabricated by electron beam lithography. A clear ratchet effect of 180° domain wall motion under a varying applied field parallel to the walls has been observed. The direction is determined by the direction of the triangle vertices. In contrast, no ratchet effect is observed when the antidot array is constituted by symmetric rhomb-shaped antidots.

Castán-Guerrero, C.; Herrero-Albillos, J.; Sesé, J.; Bartolomé, J.; Bartolomé, F.; Hierro-Rodriguez, A.; Valdés-Bango, F.; Martín, J. I.; Alameda, J. M.; García, L. M.

2014-12-01

358

Interferometric 2D and 3D tomography of photoelastic media

NASA Astrophysics Data System (ADS)

The experimental study of mechanical stress distribution in biological tissues in-vivo is of interest for some biomedical applications. This work considers the problem of light and stressed tissue interaction and the inverse problem of stress field reconstruction in 2D and 3D cases. Optical tomography is one of the most promising methods of solving these problems. This technique involves the reconstruction of the refractive index field using the measurement of waveform distortion. The reconstruction of stress field requires establishing the relation of the stress tensor to the variation of refraction index. A simple photoelastic model is a reasonable first approximation due to normal functioning of biological tissue. The simple photoelastic model is a reasonable first approximation due to normal functioning of biological tissue. The propagation equation that describes the light propagation through the optically active elastic media obtained in the solving of the forward problem in terms of geometric optics approach. Interferometric, shlieren and depolarization methods of experimental data acquisition are considered. In general, 3D state of a stressed tissue should be described by six components of the stress tensor, but only three propagation equations appear to be independent. To close the system of equations, we have used three partial differential equilibrium equations with appropriate boundary conditions. The system of equations of interferometric tomography is studied in detail. In this case, the separation of stress tensor components results from analytical solving in the Radon domain. For special case of 2D deformation we need only one propagation equation and two equilibrium equations. It is shown that 3D problem can not be reduced to 2D problem in the general case of tensor field tomography. This sends us in search of special 3D algorithms. The use of wavelets is one of perspective ways of tomographic reconstruction under strong noise. 2D and 3D algorithms of the inverse Radon transform through inverse wavelet transform in noisy conditions have been developed.

Patrickeyev, Igor; Shakhurdin, Valintin I.

2000-04-01

359

Foveated active tracking with redundant 2D motion parameters

This work presents a real-time active vision tracking system based on log-polar image motion estimation with 2D geometric deformation models. We present a very efficient parametric motion estimation method, where most computation can be done offline. We propose a redundant parameterization for the geometric deformations, which improve the convergence range of the algorithm. A foveated image representation provides extra computational

Alexandre Bernardino; José Santos-victor; Giulio Sandini

2002-01-01

360

From 2D towards 3D cartography of hollow organs

Endoscopy is a standard imaging modality commonly used in different medical fields like lesion diagnosis in hollow organs or mini-invasive surgery. Meanwhile, endoscopic data suffer from the fact that each image of a video-sequence only corresponds to a small 2D field of view. This paper presents a mosaicing algorithm leading to visually coherent large field of view maps. The ability

Christian Daul; Walter Blondel; Achraf Ben-Hamadou; Rosebet Miranda-Luna; Charles Soussen; Didier Wolf; François Guillemin

2010-01-01

361

SALE2D. General Transient Fluid Flow Algorithm

SALE2D calculates two-dimensional fluid flows at all speeds, from the incompressible limit to highly supersonic. An implicit treatment of the pressure calculation similar to that in the Implicit Continuous-fluid Eulerian (ICE) technique provides this flow speed flexibility. In addition, the computing mesh may move with the fluid in a typical Lagrangian fashion, be held fixed in an Eulerian manner, or

A. A. Amsden; H. M. Ruppel; C. W. Hirt

1981-01-01

362

Flow transitions in a 2D directional solidification model

NASA Technical Reports Server (NTRS)

Flow transitions in a Two Dimensional (2D) model of crystal growth were examined using the Bridgman-Stockbarger me thod. Using a pseudo-spectral Chebyshev collocation method, the governing equations yield solutions which exhibit a symmetry breaking flow tansition and oscillatory behavior indicative of a Hopf bifurcation at higher values of Ra. The results are discussed from fluid dynamic viewpoint, and broader implications for process models are also addressed.

Larroude, Philippe; Ouazzani, Jalil; Alexander, J. Iwan D.

1992-01-01

363

Modelling of 2D Photonic Crystals with Liquid Crystal Infilling

This paper presents 2D Finite Difference Time Domain (FDTD) and Finite Element (FE) modeling of Liquid Crystal (LC) devices. The enhancements to standard FDTD required for fully non-diagonal tensor materials such as LCs are outlined and they have been implemented in an in-house code. The results have been validated against a commercial FE package and good agreement is observed. The

Adam Rixon; Martin Cryan; Jose Pereda; Chris Railton

2009-01-01

364

Modelling of 2D Photonic Crystals with Liquid Crystal Infilling

This paper presents 2D finite difference time domain (FDTD) and finite element (FE) modeling of liquid crystal (LC) devices. The enhancements to standard FDTD required for fully non-diagonal tensor materials such as LCs are outlined and they have been implemented in an in-house code. The results have been validated against a commercial FE package and good agreement is observed. The

Adam Rixon; Martin Cryan; Jose Pereda; Chris Railton

2006-01-01

365

Valley and electric photocurrents in 2D silicon and graphene

NASA Astrophysics Data System (ADS)

We show that the optical excitation of multi-valley systems leads to valley currents which depend on the light polarization. The net electric current, determined by the vector sum of single-valley contributions, vanishes for some peculiar distributions of carriers in the valley and momentum spaces forming a pure valley current. We report on the study of this phenomenon, both experimental and theoretical, for graphene and 2D electron channels on the silicon surface.

Tarasenko, S. A.; Ivchenko, E. L.; Olbrich, P.; Ganichev, S. D.

2013-12-01

366

Statistical analysis of quiet stance sway in 2-D.

Subjects exposed to a rotating environment that perturbs their postural sway show adaptive changes in their voluntary spatially directed postural motion to restore accurate movement paths but do not exhibit any obvious learning during passive stance. We have found, however, that a variable known to characterize the degree of stochasticity in quiet stance can also reveal subtle learning phenomena in passive stance. We extended Chow and Collins (Phys Rev E 52(1):909-912, 1995) one-dimensional pinned-polymer model (PPM) to two dimensions (2-D) and then evaluated the model's ability to make analytical predictions for 2-D quiet stance. To test the model, we tracked center of mass and centers of foot pressures, and compared and contrasted stance sway for the anterior-posterior versus medio-lateral directions before, during, and after exposure to rotation at 10 rpm. Sway of the body during rotation generated Coriolis forces that acted perpendicular to the direction of sway. We found significant adaptive changes for three characteristic features of the mean square displacement (MSD) function: the exponent of the power law defined at short time scales, the proportionality constant of the power law, and the saturation plateau value defined at longer time scales. The exponent of the power law of MSD at a short time scale lies within the bounds predicted by the 2-D PPM. The change in MSD during exposure to rotation also had a power-law exponent in the range predicted by the theoretical model. We discuss the Coriolis force paradigm for studying postural and movement control and the applicability of the PPM model in 2-D for studying postural adaptation. PMID:24477760

Bakshi, Avijit; DiZio, Paul; Lackner, James R

2014-04-01

367

RADICAL: Multi-purpose 2-D Radiative Transfer Code

NASA Astrophysics Data System (ADS)

RADICAL is a multi-purpose 2-D radiative transfer code for axi-symmetric circumstellar (or circum-black-hole) envelopes /disks / tori etc. It has been extensively tested and found reliable and accurate. The code has recently been supplemented with a Variable Eddington Tensor module which enables it to solve dust continuum radiative transfer problems from very low up to extremely high optical depths with only a few (about 7) iterations at most.

Dullemond, C. P.; Mokiem, R.; Turolla, R.

2011-08-01

368

Low-energy electron-stimulated desorption of cations and neutrals from Si(111)-(7x7):C2D2.

The interactions of low-energy (5-50 eV) electrons with acetylene-d(2) (C(2)D(2)) adsorbed on the Si(111)-(7x7) surface have been examined by monitoring the stimulated desorption products. These include primary cation desorbates, D(+) and C(2)D(2)(+) (C(2)HD(+)), the fragment ion C(2)D(+), smaller amounts of C(2)(+), CDH(+) (CH(3)(+)), and neutral D((2)S). The approximately 23-25 eV threshold energies for D(+) and hydrocarbon fragment ion detection indicate involvement of two-hole or two-hole one electron final states that Coulomb explode. These multihole states can be created via Auger decay of single holes in shallow core levels localized on C or Si surface atoms. The approximately 12 eV appearance threshold for the C(2)D(2)(+) molecular ion can be correlated with direct excitation of an adsorbate-induced surface state, which may initially possess character of the A(3) surface state of Si. The 18 eV threshold for C(2)D(+) correlates with decomposition of C(2)D(2)(+) with excess vibronic energy. C(2)D(+) desorption via direct excitation of the dissociative (2)Sigma(u)(+)-type state of the C(2)D(2)(+) ion is also possible. The approximately 8 eV threshold energy for production and desorption of neutral D((2)S) may correlate with excitation of the perturbed/mixed F (1)Sigma(u)(+)<--X (1)Sigma(g)(+) and E (1)Sigma(u)(+)<--X(1)Sigma(g)(+) dissociative transitions of adsorbed acetylene molecules. Time-of-flight distributions of D((2)S) indicate both nonthermal (557 and 116 meV; 4300 and 900 K) and thermal (17 meV; 130 K) components. The two fast components can be related to the geometry of di-sigma bonded acetylene on the Si(111)-(7x7) surface. PMID:20528038

Shepperd, Kristin R; Lane, Christopher D; Orlando, Thomas M

2010-06-01

369

Low-energy electron-stimulated desorption of cations and neutrals from Si(111)-(7×7):C2D2

NASA Astrophysics Data System (ADS)

The interactions of low-energy (5-50 eV) electrons with acetylene-d2 (C2D2) adsorbed on the Si(111)-(7×7) surface have been examined by monitoring the stimulated desorption products. These include primary cation desorbates, D+ and C2D2+ (C2HD+), the fragment ion C2D+, smaller amounts of C2+, CDH+ (CH3+), and neutral D(S2). The ˜23-25 eV threshold energies for D+ and hydrocarbon fragment ion detection indicate involvement of two-hole or two-hole one electron final states that Coulomb explode. These multihole states can be created via Auger decay of single holes in shallow core levels localized on C or Si surface atoms. The ˜12 eV appearance threshold for the C2D2+ molecular ion can be correlated with direct excitation of an adsorbate-induced surface state, which may initially possess character of the A3 surface state of Si. The 18 eV threshold for C2D+ correlates with decomposition of C2D2+ with excess vibronic energy. C2D+ desorption via direct excitation of the dissociative ?u+2-type state of the C2D2+ ion is also possible. The ˜8 eV threshold energy for production and desorption of neutral D(S2) may correlate with excitation of the perturbed/mixed F ?u+1?X ?g+1 and E ?u+1?X?g+1 dissociative transitions of adsorbed acetylene molecules. Time-of-flight distributions of D(S2) indicate both nonthermal (557 and 116 meV; 4300 and 900 K) and thermal (17 meV; 130 K) components. The two fast components can be related to the geometry of di-? bonded acetylene on the Si(111)-(7×7) surface.

Shepperd, Kristin R.; Lane, Christopher D.; Orlando, Thomas M.

2010-06-01

370

Objectives: This study examined factors that affect cost, reliability, and the value of determining the cytochrome P450 2D6 (CYP2D6) polymorphism in clinical practice.Study design: The method of deoxyribonucleic acid isolation, sample preparation, oligonucleotide primers, and polymerase chain reaction procedures were scrutinized for their effect on CYP2D6 genotyping efforts. The determination of the CYP2D6 A, B, D, E, and T alleles

Shuqing Chen; Wen-Hwei Chou; Robert A. Blouin; Zhongping Mao; Laurie L. Humphries; Q. Craig Meek; John R. Neill; Walter L. Martin; Lon R. Hays; Peter J. Wedlund

1996-01-01

371

Toward Naturalistic 2D-to-3D Conversion.

Natural scene statistics (NSSs) models have been developed that make it possible to impose useful perceptually relevant priors on the luminance, colors, and depth maps of natural scenes. We show that these models can be used to develop 3D content creation algorithms that can convert monocular 2D videos into statistically natural 3D-viewable videos. First, accurate depth information on key frames is obtained via human annotation. Then, both forward and backward motion vectors are estimated and compared to decide the initial depth values, and a compensation process is applied to further improve the depth initialization. Then, the luminance/chrominance and initial depth map are decomposed by a Gabor filter bank. Each subband of depth is modeled to produce a NSS prior term. The statistical color-depth priors are combined with the spatial smoothness constraint in the depth propagation target function as a prior regularizing term. The final depth map associated with each frame of the input 2D video is optimized by minimizing the target function over all subbands. In the end, stereoscopic frames are rendered from the color frames and their associated depth maps. We evaluated the quality of the generated 3D videos using both subjective and objective quality assessment methods. The experimental results obtained on various sequences show that the presented method outperforms several state-of-the-art 2D-to-3D conversion methods. PMID:25546859

Huang, Weicheng; Cao, Xun; Lu, Ke; Dai, Qionghai; Bovik, Alan Conrad

2015-02-01

372

An Intercomparison of 2-D Models Within a Common Framework

NASA Technical Reports Server (NTRS)

A model intercomparison among the Atmospheric and Environmental Research (AER) 2-D model, the Goddard Space Flight Center (GSFC) 2-D model, and the Lawrence Livermore National Laboratory 2-D model allows us to separate differences due to model transport from those due to the model's chemical formulation. This is accomplished by constructing two hybrid models incorporating the transport parameters of the GSFC and LLNL models within the AER model framework. By comparing the results from the native models (AER and e.g. GSFC) with those from the hybrid model (e.g. AER chemistry with GSFC transport), differences due to chemistry and transport can be identified. For the analysis, we examined an inert tracer whose emission pattern is based on emission from a High Speed Civil Transport (HSCT) fleet; distributions of trace species in the 2015 atmosphere; and the response of stratospheric ozone to an HSCT fleet. Differences in NO(y) in the upper stratosphere are found between models with identical transport, implying different model representations of atmospheric chemical processes. The response of O3 concentration to HSCT aircraft emissions differs in the models from both transport-dominated differences in the HSCT-induced perturbations of H2O and NO(y) as well as from differences in the model represent at ions of O3 chemical processes. The model formulations of cold polar processes are found to be the most significant factor in creating large differences in the calculated ozone perturbations

Weisenstein, Debra K.; Ko, Malcolm K. W.; Scott, Courtney J.; Jackman, Charles H.; Fleming, Eric L.; Considine, David B.; Kinnison, Douglas E.; Connell, Peter S.; Rotman, Douglas A.; Bhartia, P. K. (Technical Monitor)

2002-01-01

373

A 2D model for a gliding arc discharge

NASA Astrophysics Data System (ADS)

In this study we report on a 2D fluid model of a gliding arc discharge in argon. Despite the 3D nature of the discharge, 2D models are found to be capable of providing very useful information about the operation of the discharge. We employ two models—an axisymmetric and a Cartesian one. We show that for the considered experiment and the conditions of a low current arc (around 30 mA) in argon, there is no significant heating of the cathode surface and the discharge is sustained by field electron emission from the cathode accompanied by the formation of a cathode spot. The obtained discharge power and voltage are relatively sensitive to the surface properties and particularly to the surface roughness, causing effectively an amplification of the normal electric field. The arc body and anode region are not influenced by this and depend mainly on the current value. The gliding of the arc is modelled by means of a 2D Cartesian model. The arc–electrode contact points are analysed and the gliding mechanism along the electrode surface is discussed. Following experimental observations, the cathode spot is simulated as jumping from one point to another. A complete arc cycle is modelled from initial ignition to arc decay. The results show that there is no interaction between the successive gliding arcs.

Kolev, St.; Bogaerts, A.

2015-02-01

374

NASA Technical Reports Server (NTRS)

An experimental program was conducted to establish some design parameters important to a supersonic film cooling system in a scramjet engine. A simple non-combusting two-dimensional flow configuration was used to isolate the film cooling phenomena. Parameters investigated include coolant delivery pressure, slot height and lip thickness, and incident shock location and strength. Design guidelines for use in engineering and trade studies are presented.

Olsen, George C.; Nowak, Robert J.; Holden, Michael S.; Baker, N. R.

1990-01-01

375

We present a comprehensive error estimation of four spatial discretization schemes of the two-dimensional Discrete Ordinates (SN) equations on Cartesian grids utilizing a Method of Manufactured Solution (MMS) benchmark suite based on variants of Larsens benchmark featuring different orders of smoothness of the underlying exact solution. The considered spatial discretization schemes include the arbitrarily high order transport methods of the

Sebastian Schunert; Yousry Y. Azmy; Damien Fournier

2011-01-01

376

Failures of information geometry

NASA Astrophysics Data System (ADS)

Information H is a unique relationship between probabilities, based on the property of independence which is central to scientific methodology. Information Geometry makes the tempting but fallacious assumption that a local metric (conventionally based on information) can be used to endow the space of probability distributions with a preferred global Riemannian metric. No such global metric can conform to H, which is "from-to" asymmetric whereas geometrical length is by definition symmetric. Accordingly, any Riemannian metric will contradict the required structure of the very distributions which are supposedly being triangulated. It follows that probabilities do not form a metric space. We give counter-examples in which alternative formulations of information, and the use of information geometry, lead to unacceptable results.

Skilling, John

2015-01-01

377

NASA Astrophysics Data System (ADS)

We describe a new and robust method to prove rigidity results in complex dynamics. The new ingredient is the geometry of the critical puzzle pieces: under control of geometry and ``complex bounds'', two generalized polynomial-like maps which admit a topological conjugacy, quasiconformal outside the filled-in Julia set, are indeed quasiconformally conjugate. The proof uses a new abstract removability-type result for quasiconformal maps, following ideas of Heinonen and Koskela and of Kallunki and Koskela, optimized for applications in complex dynamics. We prove, as the first application of this new method, that, for even criticalities distinct from two, the period two cycle of the Fibonacci renormalization operator is hyperbolic with 1 -dimensional unstable manifold.

Smania, Daniel

2007-07-01

378

Geometry of thermodynamic control

NASA Astrophysics Data System (ADS)

A fundamental problem in modern thermodynamics is how a molecular-scale machine performs useful work, while operating away from thermal equilibrium without excessive dissipation. We show that when a thermodynamic system is driven from equilibrium, in the linear response regime, the space of controllable parameters has a Riemannian geometry induced by a generalized friction tensor. This metric structure controls the dissipation of finite-time transformations, and bestows optimal protocols (geodesics on the Riemannian manifold) with many useful properties. We exploit this geometric insight to construct closed-form expressions for minimal-dissipation protocols for a model system of a particle diffusing in a one-dimensional harmonic potential, where the spring constant, inverse temperature, and trap location are adjusted simultaneously. This simple model has a surprisingly rich geometry, which we test via a numerical implementation of the Fokker-Planck equation.

Sivak, David; Zulkowski, Patrick; Deweese, Michael; Crooks, Gavin

2013-03-01

379

Gallery of Interactive Geometry

NSDL National Science Digital Library

Provided by the Center for the Computation and Visualization of Geometric Structures, a National Science Foundation Science and Technology Center at the University of Minnesota, the Gallery of Interactive Geometry offers users ten web-based applications that explore different aspects of geometry. "Build a Rainbow," for example, allows users to manipulate the light entering a prism to see the effects of changes in angle and wavelength, while "QuasiTiler" draws Penrose tilings and their generalizations. The user interface is as consistent as can be expected given the range of subjects covered; most applications present the user with a form, and return .gif files based on the parameters entered. Each application also offers background lessons on the concepts involved, as well as help with the application itself. The site is a good example of how powerful computing can be brought to the desktop through the web.

380

Entanglement entropy in even dimensional conformal field theories (CFTs) contains well-known universal terms arising from the conformal anomaly. Renyi entropies are natural generalizations of the entanglement entropy that are much less understood. Above two spacetime dimensions, the universal terms in the Renyi entropies are unknown for general entangling geometries. We conjecture a new structure in the dependence of the four-dimensional Renyi entropies on the intrinsic and extrinsic geometry of the entangling surface. We provide evidence for this conjecture by direct numerical computations in the free scalar and fermion field theories. The computation involves relating the four-dimensional free massless Renyi entropies across cylindrical entangling surfaces to corresponding three-dimensional massive Renyi entropies across circular entangling surfaces. Our numerical technique also allows us to directly probe other interesting aspects of three-dimensional Renyi entropy, including the massless renormalized Renyi entropy and calculable contributions to the perimeter law.

Jeongseog Lee; Lauren McGough; Benjamin R. Safdi

2014-03-06

381

NASA Astrophysics Data System (ADS)

The inverse problem of calculus of variations and s-equivalence are re-examined by using results obtained from non-commutative geometry ideas. The role played by the structure of the modified Poisson brackets is discussed in a general context and it is argued that classical s-equivalent systems may be non-equivalent at the quantum mechanical level. This last fact is explicitly discussed comparing different approaches to deal with the Nair-Polychronakos oscillator.

Hojman, Sergio A.; Gamboa, J.; Méndez, F.

2012-10-01

382

Freezing in confined geometries

NASA Technical Reports Server (NTRS)

Results of detailed structural studies, using elastic neutron scattering, of the freezing of liquid O2 and D2 in porous vycor glass, are presented. The experimental studies have been complemented by computer simulations of the dynamics of freezing of a Lennard-Jones liquid in narrow channels bounded by molecular walls. Results point to a new simple physical interpretation of freezing in confined geometries.

Sokol, P. E.; Ma, W. J.; Herwig, K. W.; Snow, W. M.; Wang, Y.; Koplik, Joel; Banavar, Jayanth R.

1992-01-01

383

The fundamental geometry is outlined that underlies all biplots of a data-matrix X of n cases and p variables. Cases are represented by n points and variables by a reference system. The reference system for quantitative variables may be orthogonal Cartesian axes, other linear axes or nonlinear trajectories. The reference system for categorical variables is a set of category-level-points (CLPs)

John C. Gower

384

Circumference of Taxicab Geometry Circles.

ERIC Educational Resources Information Center

Presented is an activity in which students apply familiar concepts of geometry to novel settings. Using square dot paper and isometric dot paper, students trace routes and determine the geometry of each circle. (KR)

Litwiller, Bonnie H.; Duncan, David R.

1991-01-01

385

A Lorentz Covariant Noncommutative Geometry

A noncommutative geometry that preserves lorentz covariance was introduced by Hartland Snyder in 1947. We show that this geometry has unusual properties under momentum translation, and derive for it a form of star product.

A. Lewis Licht

2005-12-13

386

Geometry for the Secondary School

ERIC Educational Resources Information Center

A sequential but non-axiomatic high school geometry course which includes Euclidean, transformation, and analytic geometry and vectors and matrices, and emphasizes the invariance property of transformations, is outlined. Sample problems, solutions, and comments are included. (MN)

Moalem, D.

1977-01-01

387

Preliminary abatement device evaluation: 1D-2D KGM cyclone design

Technology Transfer Automated Retrieval System (TEKTRAN)

Cyclones are predominately used in controlling cotton gin particulate matter (PM) emissions. The most commonly used cyclone designs are the 2D-2D and 1D-3D; however other designs such as the 1D-2D KGM have or are currently being used. A 1D-2D cyclone has a barrel length equal to the barrel diamete...

388

A system for a new two-dimensional code: Secure 2D code

A new 2D code called Secure 2D code is de- signed in this paper, both encoder and decoder are also pro- posed. Secure 2D code can store any kind of data and pro- vides high security. With regard to security, the input data is divided into two parts: general and secret. The general data is transformed into a 2D code

Chung-tsai Yeh; Ling-hwei Chen

1998-01-01

389

On variational data assimilation for 1D and 2D fluvial hydraulics

to variational data assimilation (VDA) as applied to river hydraulics (1D and 2D shallow water models). In real seek to couple accurately a 1D global net-model (rivers net) and a local 2D shallow water model (zoom conditions. The 2D forward model The 2D forward model considered rely on the shallow water equations (SWE) (h

Boyer, Edmond

390

Noncommutative geometry and arithmetics

NASA Astrophysics Data System (ADS)

We intend to illustrate how the methods of noncommutative geometry are currently used to tackle problems in class field theory. Noncommutative geometry enables one to think geometrically in situations in which the classical notion of space formed of points is no longer adequate, and thus a “noncommutative space” is needed; a full account of this approach is given in [3] by its main contributor, Alain Connes. The class field theory, i.e., number theory within the realm of Galois theory, is undoubtedly one of the main achievements in arithmetics, leading to an important algebraic machinery; for a modern overview, see [23]. The relationship between noncommutative geometry and number theory is one of the many themes treated in [22, 7-9, 11], a small part of which we will try to put in a more down-to-earth perspective, illustrating through an example what should be called an “application of physics to mathematics,” and our only purpose is to introduce nonspecialists to this beautiful area.

Almeida, P.

2009-09-01

391

Matter in Toy Dynamical Geometries

One of the objectives of theories describing quantum dynamical geometry is to compute expectation values of geometrical observables. The results of such computations can be affected by whether or not matter is taken into account. It is thus important to understand to what extent and to what effect matter can affect dynamical geometries. Using a simple model, it is shown that matter can effectively mold a geometry into an isotropic configuration. Implications for "atomistic" models of quantum geometry are briefly discussed.

Tomasz Konopka

2009-03-25

392

A Nonrigid Kernel-Based Framework for 2D-3D Pose Estimation and 2D Image Segmentation

In this work, we present a nonrigid approach to jointly solving the tasks of 2D-3D pose estimation and 2D image segmentation. In general, most frameworks that couple both pose estimation and segmentation assume that one has exact knowledge of the 3D object. However, under nonideal conditions, this assumption may be violated if only a general class to which a given shape belongs is given (e.g., cars, boats, or planes). Thus, we propose to solve the 2D-3D pose estimation and 2D image segmentation via nonlinear manifold learning of 3D embedded shapes for a general class of objects or deformations for which one may not be able to associate a skeleton model. Thus, the novelty of our method is threefold: First, we present and derive a gradient flow for the task of nonrigid pose estimation and segmentation. Second, due to the possible nonlinear structures of one’s training set, we evolve the preimage obtained through kernel PCA for the task of shape analysis. Third, we show that the derivation for shape weights is general. This allows us to use various kernels, as well as other statistical learning methodologies, with only minimal changes needing to be made to the overall shape evolution scheme. In contrast with other techniques, we approach the nonrigid problem, which is an infinite-dimensional task, with a finite-dimensional optimization scheme. More importantly, we do not explicitly need to know the interaction between various shapes such as that needed for skeleton models as this is done implicitly through shape learning. We provide experimental results on several challenging pose estimation and segmentation scenarios. PMID:20733218

Sandhu, Romeil; Dambreville, Samuel; Yezzi, Anthony; Tannenbaum, Allen

2013-01-01

393

2D Riemann-Christoffel curvature tensor via a 3D space using a specialized permutation scheme

When a space in which Christoffel symbols of the second kind are symmetrical in lower indices exists, it makes for a supplement to the standard procedure when a 2D surface is normally induced from the geometry of the surrounding 3D space in which the surface is embedded. There it appears appropriate to use a scheme for straightforward permutation of indices of Gkij, when such a space would make this transformation possible, so as to obtain the components of the 2D Riemann-Christoffel tensor (here expressed in geodetic coordinates for an ellipsoid of revolution, of use in geophysics). By applying my scheme I find the corresponding indices in 2D and 3D supplement-spaces, and I compute components of the Riemann-Christoffel tensor. By operating over the elements of the projections alone, the all-known value of 1/MN for the Gaussian curvature on an ellipsoid of revolution is obtained. To further validate my scheme, I show that in such a 3D space the tangent vector to a PHI-curve for LAM=const1 would be parallel to...

Omerbashich, Mensur

2009-01-01

394

We have observed the conformation-dependent electronic coupling between the monomeric subunits of a dinucleotide of 2-aminopurine (2-AP), a fluorescent analog of the nucleic acid base adenine. This was accomplished by extending two-dimensional fluorescence spectroscopy (2D FS) – a fluorescence-detected variation of 2D electronic spectroscopy – to excite molecular transitions in the ultraviolet (UV) regime. A collinear sequence of four ultrafast laser pulses centered at 323 nm was used to resonantly excite the coupled transitions of 2-AP dinucleotide. The phases of the optical pulses were continuously swept at kilohertz frequencies, and the ensuing nonlinear fluorescence was phase-synchronously detected at 370 nm. Upon optimization of a point-dipole coupling model to our data, we found that in aqueous buffer the 2-AP dinucleotide adopts an average conformation in which the purine bases are non-helically stacked (center-to-center distance R12 = 3.5 Å ± 0.5 Å, twist angle ?12 = 5° ± 5°), which differs from the conformation of such adjacent bases in duplex DNA. These experiments establish UV-2D FS as a method for examining the local conformations of an adjacent pair of fluorescent nucleotides substituted into specific DNA or RNA constructs, which will serve as a powerful probe to interpret, in structural terms, biologically significant local conformational changes within the nucleic acid framework of protein-nucleic acid complexes. PMID:24223491

Widom, Julia R.; Johnson, Neil P.; von Hippel, Peter H.; Marcus, Andrew H.

2013-01-01

395

TOF Geometry TOF Software Review

TOF Geometry W.J. Llope TOF Software Review Nov. 2008, BNL Â· the "jigsaw puzzle" Â· simple acceptance simulation Â· final tray-local geometry Â· installed tray locations Â· many ~20mil effects from manufacturing tolerances Â· upVPD-local geometry Â· geant simulations Â· positioning Â· summary #12

Llope, William J.

396

Geometry, noncommutative algebra and representations

Geometry, noncommutative algebra and representations Iain Gordon http://www.maths.ed.ac.uk/~igordon/ University of Edinburgh 16th December 2006 1 Iain Gordon Geometry, noncommutative algebra and representations Outline 1 Geometry and Commutative Algebra 2 Singularities and Resolutions 3 Noncommutative Algebra

Gordon, Iain

397

The geometry package Hideo Umeki

The geometry package Hideo Umeki hideo.umeki@toshiba.co.jp 1999/10/07 (v2.2) Abstract This package. Contents 1 Preface to Version 2 1 2 Introduction 2 3 Page Geometry 2 3.1 Layout Dimensions . . . . . . 2 3: Â· The geometry options using the keyval scheme can be set in the optional argument to the \\usepackage command

Gkioulekas, Eleftherios - Department of Mathematics, University of Texas

398

Geometry Textures Rodrigo de Toledo

Geometry Textures Rodrigo de Toledo Tecgraf Â PUC-Rio Rio de Janeiro - RJ, Brasil rtoledo but applied to the whole object. Tessel- lated models are converted into geometry textures, a geo- metric with LOD speed-up while preserving original quality. 1 Introduction The goal of geometry textures

Paris-Sud XI, UniversitÃ© de

399

SIMULATION OF HUMAN ISCHEMIC STROKE IN REALISTIC 3D GEOMETRY: A NUMERICAL STRATEGY

and as expected, 2D and also fully 3D numerical simulations of ischemic strokes for a realistic brain geometry cause of death worldwide and the first cause of acquired disability in adults. In the United States, this disease strikes once every 40 seconds and causes death ev- ery 4 minutes, with an estimated 41.6% death

400

Investigation of the Effect of Deformable Trailing Edge Geometry Control Systems on Flutter Velocity

Investigation of the Effect of Deformable Trailing Edge Geometry Control Systems on Flutter control system on flutter velocity in the 2D case. The focus of this work is on the difference in flutter that the classical flutter limit is reached for a typical 1.5 MW blade if the rotational velocity is multiplied

401

Super Cooled Large Droplet Analysis of Several Geometries Using LEWICE3D Version 3

NASA Technical Reports Server (NTRS)

Super Cooled Large Droplet (SLD) collection efficiency calculations were performed for several geometries using the LEWICE3D Version 3 software. The computations were performed using the NASA Glenn Research Center SLD splashing model which has been incorporated into the LEWICE3D Version 3 software. Comparisons to experiment were made where available. The geometries included two straight wings, a swept 64A008 wing tip, two high lift geometries, and the generic commercial transport DLR-F4 wing body configuration. In general the LEWICE3D Version 3 computations compared well with the 2D LEWICE 3.2.2 results and with experimental data where available.

Bidwell, Colin S.

2011-01-01

402

A novel time dependent gamma evaluation function for dynamic 2D and 3D dose distributions

NASA Astrophysics Data System (ADS)

Modern external beam radiotherapy requires detailed verification and quality assurance so that confidence can be placed on both the delivery of a single treatment fraction and on the consistency of delivery throughout the treatment course. To verify dose distributions, a comparison between prediction and measurement must be made. Comparisons between two dose distributions are commonly performed using a Gamma evaluation which is a calculation of two quantities on a pixel by pixel basis; the dose difference, and the distance to agreement. By providing acceptance criteria (e.g. 3%, 3?mm), the function will find the most appropriate match within its two degrees of freedom. For complex dynamic treatments such as IMRT or VMAT it is important to verify the dose delivery in a time dependent manner and so a gamma evaluation that includes a degree of freedom in the time domain via a third parameter, time to agreement, is presented here. A C++ (mex) based gamma function was created that could be run on either CPU and GPU computing platforms that would allow a degree of freedom in the time domain. Simple test cases were created in both 2D and 3D comprising of simple geometrical shapes with well-defined boundaries varying over time. Changes of varying magnitude in either space or time were introduced and repeated gamma analyses were performed varying the criteria. A clinical VMAT case was also included, artificial air bubbles of varying size were introduced to a patient geometry, along with shifts of varying magnitude in treatment time. For all test cases where errors in distance, dose or time were introduced, the time dependent gamma evaluation could accurately highlight the errors. The time dependent gamma function presented here allows time to be included as a degree of freedom in gamma evaluations. The function allows for 2D and 3D data sets which are varying over time to be compared using appropriate criteria without penalising minor offsets of subsequent radiation fields in time.

Podesta, Mark; CGG Persoon, Lucas; Verhaegen, Frank

2014-10-01

403

550 P.2d 1001 Page 1 17 Cal.3d 129, 550 P.2d 1001, 130 Cal.Rptr. 465

550 P.2d 1001 Page 1 17 Cal.3d 129, 550 P.2d 1001, 130 Cal.Rptr. 465 (Cite as: 17 Cal.3d 129, 550 P.2d 1001) BOALT STUDENTS Â PLEASE READ PAGES 7-9 (*140-*142 Â STARTING WITH: City's Power to Provide. Works. #12;550 P.2d 1001 Page 2 17 Cal.3d 129, 550 P.2d 1001, 130 Cal.Rptr. 465 (Cite as: 17 Cal.3d 129

Kammen, Daniel M.

404

This paper discusses the invariance of the second-order modes of 2-D separable denominator digital filters under frequency transformation. This paper first derives a state-space description for 2-D digital filters obtained by 2-D frequency transformation and then represents the controllability Gramians and the observability Gramians of the transformed 2-D digital filters. This description proves that the second-order modes of 2-D separable

Shunsuke Koshita; Masayuki Kawamata

2005-01-01

405

Cloud geometry effects on atmospheric solar absorption

A 3D broadband solar radiative transfer scheme is formulated by integrating a Monte Carlo photon transport algorithm with the Fu-Liou radiation model. It is applied to fields of tropical mesoscale convective clouds and subtropical marine boundary layer clouds that were generated by a 2D cloud-resolving model. The effects of cloud geometry on the radiative energy budget are examined by comparing the full-resolution Monte Carlo results with those from the independent column approximation (ICA) that applies the plane-parallel radiation model to each column. For the tropical convective cloud system, it is found that cloud geometry effects always enhance atmospheric solar absorption regardless of solar zenith angle. In a large horizontal domain (512 km), differences in domain-averaged atmospheric absorption between the Monte Carlo and the ICA are less than 4 W m{sup {minus}2} in the daytime. However, for a smaller domain (e.g., 75 km) containing a cluster of deep convective towers, domain-averaged absorption can be enhanced by more than 20 W m{sup {minus}2}. For a subtropical marine boundary layer cloud system during the stratus-to-cumulus transition, calculations show that the ICA works very well for domain-averaged fluxes of the stratocumulus cloud fields even for a very small domain (4.8 km). For the trade cumulus cloud field, the effects of cloud sides and horizontal transport of photons become more significant. Calculations have also been made for both cloud systems including black carbon aerosol and a water vapor continuum. It is found that cloud geometry produces no discernible effects on the absorption enhancement due to the black carbon aerosol and water vapor continuum. The current study indicates that the atmospheric absorption enhancement due to cloud-related 3D photon transport is small. This enhancement could not explain the excess absorption suggested by recent studies.

Fu, Q.; Cribb, M.C.; Barker, H.W.; Krueger, S.K.; Grossman, A.

2000-04-15

406

Human erythrocytes analyzed by generalized 2D Raman correlation spectroscopy

NASA Astrophysics Data System (ADS)

The most numerous elements of the blood cells, erythrocytes, consist mainly of two components: homogeneous interior filled with hemoglobin and closure which is the cell membrane. To gain insight into their specific properties we studied the process of disintegration, considering these two constituents, and comparing the natural aging process of human healthy blood cells. MicroRaman spectra of hemoglobin within the single RBC were recorded using 514.5, and 785 nm laser lines. The generalized 2D correlation method was applied to analyze the collected spectra. The time passed from blood donation was regarded as an external perturbation. The time was no more than 40 days according to the current storage limit of blood banks, although, the average RBC life span is 120 days. An analysis of the prominent synchronous and asynchronous cross peaks allow us to get insight into the mechanism of hemoglobin decomposition. Appearing asynchronous cross-peaks point towards globin and heme separation from each other, while synchronous shows already broken globin into individual amino acids. Raman scattering analysis of hemoglobin “wrapping”, i.e. healthy erythrocyte ghosts, allows for the following peculiarity of their behavior. The increasing power of the excitation laser induced alterations in the assemblage of membrane lipids. 2D correlation maps, obtained with increasing laser power recognized as an external perturbation, allows for the consideration of alterations in the erythrocyte membrane structure and composition, which occurs first in the proteins. Cross-peaks were observed indicating an asynchronous correlation between the senescent-cell antigen (SCA) and heme or proteins vibrations. The EPR spectra of the whole blood was analyzed regarding time as an external stimulus. The 2D correlation spectra points towards participation of the selected metal ion centers in the disintegration process.

Wese?ucha-Birczy?ska, Aleksandra; Kozicki, Mateusz; Czepiel, Jacek; ?abanowska, Maria; Nowak, Piotr; Kowalczyk, Grzegorz; Kurdziel, Magdalena; Birczy?ska, Malwina; Biesiada, Gra?yna; Mach, Tomasz; Garlicki, Aleksander

2014-07-01

407

Progress in 2D photonic crystal Fano resonance photonics

NASA Astrophysics Data System (ADS)

In contrast to a conventional symmetric Lorentzian resonance, Fano resonance is predominantly used to describe asymmetric-shaped resonances, which arise from the constructive and destructive interference of discrete resonance states with broadband continuum states. This phenomenon and the underlying mechanisms, being common and ubiquitous in many realms of physical sciences, can be found in a wide variety of nanophotonic structures and quantum systems, such as quantum dots, photonic crystals, plasmonics, and metamaterials. The asymmetric and steep dispersion of the Fano resonance profile promises applications for a wide range of photonic devices, such as optical filters, switches, sensors, broadband reflectors, lasers, detectors, slow-light and non-linear devices, etc. With advances in nanotechnology, impressive progress has been made in the emerging field of nanophotonic structures. One of the most attractive nanophotonic structures for integrated photonics is the two-dimensional photonic crystal slab (2D PCS), which can be integrated into a wide range of photonic devices. The objective of this manuscript is to provide an in depth review of the progress made in the general area of Fano resonance photonics, focusing on the photonic devices based on 2D PCS structures. General discussions are provided on the origins and characteristics of Fano resonances in 2D PCSs. A nanomembrane transfer printing fabrication technique is also reviewed, which is critical for the heterogeneous integrated Fano resonance photonics. The majority of the remaining sections review progress made on various photonic devices and structures, such as high quality factor filters, membrane reflectors, membrane lasers, detectors and sensors, as well as structures and phenomena related to Fano resonance slow light effect, nonlinearity, and optical forces in coupled PCSs. It is expected that further advances in the field will lead to more significant advances towards 3D integrated photonics, flat optics, and flexible optoelectronics, with lasting impact in areas ranging from computing, communications, to sensing and imaging systems.

Zhou, Weidong; Zhao, Deyin; Shuai, Yi-Chen; Yang, Hongjun; Chuwongin, Santhad; Chadha, Arvinder; Seo, Jung-Hun; Wang, Ken X.; Liu, Victor; Ma, Zhenqiang; Fan, Shanhui

2014-01-01

408

Efficient 2D inversion of long ERT sections

NASA Astrophysics Data System (ADS)

In this work a new algorithm for the efficient and fast two dimensional (2D) inversion of long electrical resistivity tomography (ERT) sections is introduced. The algorithm is based on 2.5D finite element method (FEM) scheme to solve Poisson's equation that describes the current flow into the earth's subsurface. The adjoint equation technique was incorporated into the FEM framework to estimate the sensitivity values. The reconstructed 2D resistivity models are recovered through an iterative, non-linear smoothness constrained least-squares approach. The algorithm further incorporates an experimental procedure to avoid the calculation and storage of the entire Jacobian matrix. The basic concept of this new algorithm relies on the fact that for every measurement there is a number of model parameters which are located in parts of the 2-D model at distant locations from potential and current electrodes. The corresponding absolute Jacobian matrix values in such cases are very small (almost zero) and can be omitted by the Jacobian calculation. Around every measurement a fixed rectangular threshold region is defined a-priori based on geometrical criteria. The algorithm calculates only Jacobian matrix values for the model parameters that are included in this threshold area omitting the calculation of the Jacobian entries related to model parameters outside this region. This approach speeds up the Jacobian matrix calculations while the efficient storage of the sparse Jacobian and Smoothness matrices and the inversion using an iterative routine like LSQR method increase significantly the inversion speed and reduce the memory requirements. The new algorithm is almost more than one order of magnitude (~ 30 times) faster and consumes one order of magnitude (~ 90%) less storage memory than the original one based on full Jacobian calculations for typical applications. The application of the new algorithm to synthetic and real data sets shows that the reconstructed models exhibit comparable accuracy to the standard inversion approach.

Tsourlos, Panagiotis; Papadopoulos, Nikos; Papazachos, Costas; Yi, Myeong-Jong; Kim, Jung-Ho

2014-06-01

409

2D reflection seismic investigations in the Kevitsa Ni-Cu-PGE deposit, northern Finland

NASA Astrophysics Data System (ADS)

In 2007, 2D reflection seismic survey was conducted in the Kevitsa Ni-Cu-PGE (platinum group elements) deposit, northern Finland as a part of the HIRE (High Resolution Reflection Seismics for Ore Exploration 2007-2010) project of the Geological Survey of Finland. The Kevitsa 2D seismic survey consists of four connected survey lines, each approximately 6-8 km long. The survey lines traverse the ore-bearing Kevitsa intrusive complex and partly also the geological units surrounding it, thus providing an insight to the structural make-up of the complex. The aim of the survey was to delineate the overall shape and basal contact of the Kevitsa ultramafic intrusive complex at depth, to study the seismic response of the disseminated Kevitsa Ni-Cu-PGE deposit, and to potentially find indications for new ore deposits. Herein, we present results from processing and interpretation of the Kevitsa 2D reflection seismic data. In the data processing sequence, specific focus was given to finding optimal CDP-line geometries for the crooked-line survey profiles, and to detailed velocity analysis. We also conducted a simplified cross-dip analysis to assess the potential cross-profile dips of the reflectors, however, application of the cross-dip corrections was found to be unnecessary, and our conventional processing sequence involving prestack DMO corrections followed by poststack migration resulted in high-quality images of the subsurface. The seismic sections presented in this work reveal a detailed reflectivity structure of the uppermost 5 kilometers. The known Kevitsa deposit was found to have a specific seismic signature, and the seismic images were used to establish previously unknown shape and extent of the ore-bearing Kevitsa intrusive complex, thus providing a framework for effective future exploration in the area. Interestingly, the data reveal complex internal reflectivity structure within the intrusion, suggesting multiple levels of intrusion within the pre-existing stratigraphy, and a deeper continuation of the intrusion. A complicated pattern of faults brackets the known deposit, and a series of major fault and shear zones brackets the Kevitsa intrusive complex as a whole. The major structures identified in the seismic sections may potentially be related to the origin of Kevitsa. The data also indicate a possible relationship between the Kevitsa intrusive complex and the nearby Satovaara complex, however, the exact relationship of this complex to the Kevitsa intrusive complex needs to be established through future drilling. Acknowledgements: Kevitsa Mining Oy/First Quantum Minerals Ltd

Koivisto, E.; Malehmir, A.; Heikkinen, P.; Heinonen, S.; Kukkonen, I.

2012-04-01

410

Nonperturbative 2d Quantum Gravity via Supersymmetric String

NASA Astrophysics Data System (ADS)

The Parisi-Marinari suggestion to treat 2d quantum gravity as ground state of the 1d supersymmetric string is elaborated in some detail. The third order linear ordinary differential equation describing in the double scaling limit the distribution of eigenvalues of the random matrix (i.e., the Liouville field) is derived and studied numerically. Unlike the Painlevé equation, our equation leads to continuous spectrum; however, the nonperturbative effects display themselves as quantum oscillations on top of smooth WKB distribution. Nonperturbative solution is free of any ambiguities.

Karliner, Marek; Migdal, Sasha

411

Transport Experiments on 2D Correlated Electron Physics in Semiconductors

This research project was designed to investigate experimentally the transport properties of the 2D electrons in Si and GaAs, two prototype semiconductors, in several new physical regimes that were previously inaccessible to experiments. The research focused on the strongly correlated electron physics in the dilute density limit, where the electron potential energy to kinetic energy ratio rs>>1, and on the fractional quantum Hall effect related physics in nuclear demagnetization refrigerator temperature range on samples with new levels of purity and controlled random disorder.

Tsui, Daniel

2014-03-24

412

2-D FIR interferometry and polarimetry on TPX

NASA Astrophysics Data System (ADS)

A multiple fan-beam approach to 2-D FIR interferometry and polarimetry is under investigation for use on next generation tokamaks such as TPX. The approach utilizes a small number (3-5) of inside launch fan beams, and a finite number (5-15) of receive horns positioned within the vacuum vessel on the outboard side of the plasma. Positioning of the horns is achieved with minimal penetration of internal structures, within the design constraints dictated by a highly restricted viewing access. The choice of operating frequency is discussed considering both physics and design issues.

Geck, W. R.; Qin, X.; Liao, J.; Domier, C. W.; Luhmann, N. C., Jr.

1995-01-01

413

Effective diffusion coefficient in 2D periodic channels

NASA Astrophysics Data System (ADS)

Calculation of the effective diffusion coefficient D(x), depending on the longitudinal coordinate x in 2D channels with periodically corrugated walls, is revisited. Instead of scaling the transverse lengths and applying the standard homogenization techniques, we propose an algorithm based on formulation of the problem in the complex plane. A simple model is solved to explain the behavior of D(x) in the channels with short periods L, observed by Brownian simulations of Dagdug et al. [J. Chem. Phys. 133, 034707 (2010)].

Kalinay, Pavol

2014-10-01

414

Correlation functions for the 2D random bonds Potts models

NASA Astrophysics Data System (ADS)

We study the spin-spin and energy-energy correlation functions for the 2D Ising and 3-states Potts model with random bonds at the critical point. The procedure employed is the renormalisation group approach of the perturbation series around the conformal field theories representing the pure models. For the Ising model, we obtain a crossover in the amplitude for the correlation functions which doesn't change the critical exponent. For the 3-state Potts model, we found a shift in the critical exponent produced by randomness. A comparison with numerical data is discussed briefly.

Dotsenko, Vladimir; Picco, Marco; Pujol, Pierre

1996-01-01

415

2D/3D Synthetic Vision Navigation Display

NASA Technical Reports Server (NTRS)

Flight-deck display software was designed and developed at NASA Langley Research Center to provide two-dimensional (2D) and three-dimensional (3D) terrain, obstacle, and flight-path perspectives on a single navigation display. The objective was to optimize the presentation of synthetic vision (SV) system technology that permits pilots to view multiple perspectives of flight-deck display symbology and 3D terrain information. Research was conducted to evaluate the efficacy of the concept. The concept has numerous unique implementation features that would permit enhanced operational concepts and efficiencies in both current and future aircraft.

Prinzel, Lawrence J., III; Kramer, Lynda J.; Arthur, J. J., III; Bailey, Randall E.; Sweeters, jason L.

2008-01-01

416

Recent update of the RPLUS2D/3D codes

NASA Technical Reports Server (NTRS)

The development of the RPLUS2D/3D codes is summarized. These codes utilize LU algorithms to solve chemical non-equilibrium flows in a body-fitted coordinate system. The motivation behind the development of these codes is the need to numerically predict chemical non-equilibrium flows for the National AeroSpace Plane Program. Recent improvements include vectorization method, blocking algorithms for geometric flexibility, out-of-core storage for large-size problems, and an LU-SW/UP combination for CPU-time efficiency and solution quality.

Tsai, Y.-L. Peter

1991-01-01

417

Beam-Plasma Instabilities in a 2D Yukawa Lattice

We consider a 2D Yukawa lattice of grains, with a beam of other charged grains moving in the lattice plane. In contrast to Vlasov plasmas, where the electrostatic instability excited by the beam is only longitudinal, here both longitudinal and transverse instabilities of the lattice phonons can develop. We determine and compare the transverse and longitudinal growth rates. The growth rate spectrum in wave number space exhibits remarkable gaps where no instability can develop. Depending on the system parameters, the transverse instability can be selectively excited.

Kyrkos, S. [Department of Chemistry and Physics, Le Moyne College, Syracuse, New York 13214 (United States); Kalman, G. J. [Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467 (United States); Rosenberg, M. [Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California 92093 (United States)

2009-06-05

418

2-d finite barrier rectangular quantum dots II: Dirac description

NASA Astrophysics Data System (ADS)

The Schrödinger description of 2-d finite barrier rectangular quantum dots [1] is expanded to Dirac description through transfer matrices and reflection and rotation symmetries of the dot system. Inexactness of wave vector components of spinors is then reduced to two relations which lead to two different bispinors and four quantized transcendental energy relations corresponding to even-even, odd-odd and even-odd, odd-even factorizing functions of each bispinor. In order to show the spin effect on the dot energy levels, the solutions of the transcendental relations of the Schrödinger and Dirac descriptions are plotted.

Ata, Engin; Demirhan, Do?an; Büyükk?l?ç, Fevzi

2015-03-01

419

Symmetries in non-perturbative 2-d quantum gravity

In this paper based on the Korteweg-de Vries (KdV) hierarchy formulation of non-perturbative 2-d quantum gravity, the authors investigate the symmetries of the system. Particularly, it is shown that the recently found Virasoro constraints are due to the non-isospectral symmetries of KdV hierarchy, which can be interpreted as SL(2, C) invariance and the independence of the moduli of the auxiliary infinite genus hyperelliptic Riemann surfaces which appear in the Krichever construction of soliton solutions.

La, H. (Pennsylvania Univ., Philadelphia, PA (United States). Dept. of Physics)

1991-03-07

420

Unitary matrix models and 2D quantum gravity

In this paper the KdV and modified KdV integrable hierarchies are shown to be different descriptions of the same 2D gravitational system - open-closed string theory. Non-perturbative solutions of the multicritical unitary matrix models map to non-singular solutions of the renormalization group equation for the string susceptibility, [P, Q] = Q. The authors also demonstrate that the large-N solutions of unitary matrix integrals in external fields, studied by Gross and Newman, equal the non-singular pure closed-string solutions of [[bar P], Q] = Q.

Dalley, S. (Princeton Univ., NJ (United States). Joseph Henry Labs.); Johnson, C.V.; Morris, T.R. (Southampton Univ. (United Kingdom). Dept. of Physics); Watterstam, A. (Inst. for Theoretical Physics, Chalmers Inst. of Tech., S-412 96 Goteborg (Sweden))

1992-09-21

421

Mixing and dispersion upscaling from a 2D pore scale characterization of Lagrangian velocities

NASA Astrophysics Data System (ADS)

Mixing and reactive transport are primarily controlled by the interplay between diffusion, advection and reaction at the pore scale. Yet, how heterogeneity of the pore scale velocity field impacts these processes is still an open question. Here we present an experimental investigation of the distribution and correlations in pore scale velocities and their relation to upscaled dispersion and mixing, for different pore geometries. We use a quasi two-dimensional (2D) horizontal set up, consisting of two glass plates filled with cylinders representing the grains of the porous medium : the cell is built using soft lithography, which allows for full control of the system geometry. The local velocity field is quantified from particle tracking velocimetry using microsphere solid tracers. Their displacement is purely advective, as the particle size is chosen sufficiently large so as to neglect diffusion. We thus obtain particle trajectories and lagrangian velocities in the entire system. The experimental results are compared with and validated by finite element numerical simulations performed with comsol. The measured velocity fields show the existence of a network of preferential flow paths in channels with high velocities, as well as very low velocity in stagnation zones, with a non Gaussian probability density function of the velocities. Lagrangian velocities are long range correlated in time, which implies a non-fickian scaling of the longitudinal variance of particle positions. The analysis of Lagrangian velocities is used to upscale both dispersion and mixing. The predictions of these upscaled models, parameterized by the velocity field properties, are compared to conservative tracer tests data, performed in the same porous media.

Turuban, R.; De Anna, P.; Jimenez Martinez, J.; Tabuteau, H.; Meheust, Y.; Le Borgne, T.

2013-12-01

422

Quasi 3D dosimetry (EPID, conventional 2D/3D detector matrices)

NASA Astrophysics Data System (ADS)

Patient specific pretreatment measurement for IMRT and VMAT QA should preferably give information with a high resolution in 3D. The ability to distinguish complex treatment plans, i.e. treatment plans with a difference between measured and calculated dose distributions that exceeds a specified tolerance, puts high demands on the dosimetry system used for the pretreatment measurements and the results of the measurement evaluation needs a clinical interpretation. There are a number of commercial dosimetry systems designed for pretreatment IMRT QA measurements. 2D arrays such as MapCHECK® (Sun Nuclear), MatriXXEvolution (IBA Dosimetry) and OCTAVIOUS® 1500 (PTW), 3D phantoms such as OCTAVIUS® 4D (PTW), ArcCHECK® (Sun Nuclear) and Delta4 (ScandiDos) and software for EPID dosimetry and 3D reconstruction of the dose in the patient geometry such as EPIDoseTM (Sun Nuclear) and Dosimetry CheckTM (Math Resolutions) are available. None of those dosimetry systems can measure the 3D dose distribution with a high resolution (full 3D dose distribution). Those systems can be called quasi 3D dosimetry systems. To be able to estimate the delivered dose in full 3D the user is dependent on a calculation algorithm in the software of the dosimetry system. All the vendors of the dosimetry systems mentioned above provide calculation algorithms to reconstruct a full 3D dose in the patient geometry. This enables analyzes of the difference between measured and calculated dose distributions in DVHs of the structures of clinical interest which facilitates the clinical interpretation and is a promising tool to be used for pretreatment IMRT QA measurements. However, independent validation studies on the accuracy of those algorithms are scarce. Pretreatment IMRT QA using the quasi 3D dosimetry systems mentioned above rely on both measurement uncertainty and accuracy of calculation algorithms. In this article, these quasi 3D dosimetry systems and their use in patient specific pretreatment IMRT/VMAT QA will be discussed.

Bäck, A.

2015-01-01

423

The concept of number and its generalization has played a central role in the development of mathematics over many centuries and many civilizations. Noteworthy milestones in this long and arduous process were the developments of the real and complex numbers which have achieved universal acceptance. Serious attempts have been made at further extensions, such as Hamiltons quaternions, Grassmann's exterior algebra and Clifford's geometric algebra. By examining the geometry of moving planes, we show how new mathematics is within reach, if the will to learn these powerful methods can be found.

Garret Sobczyk

2007-09-29

424

Energy Distribution in 2d Stringy Black Hole Backgrounds

We utilize Moller's and Einstein's energy-momentum complexes in order to explicitly evaluate the energy distributions associated with the two-dimensional "Schwarzschild" and "Reissner-Nordstrom" black hole backgrounds. While Moller's prescription provides meaningful physical results, Einstein's prescription fails to do so in the aforementioned gravitational backgrounds. These results hold for all two-dimensional static black hole geometries. The results obtained within this context are exploited in order Seifert's hypothesis to be investigated.

Elias C. Vagenas

2003-03-03

425

MORSE-CGA: a Monte Carlo radiation transport code with array geometry capability

The MORSE-CG computer code system has been revised to add a new geometry module MARS, which is the combinatorial geometry package that allows multiple arrays for specifying geometries. The new code system is known as MORSE-CGA where CGA indicates Combinatorial Geometry Array. The PICTURE code, which makes printer plots of 2-D slices through a combinatorial geometry mock-up, has also been revised to handle the MARS array capability. This report will document the changes required in MORSE-CG and in PICTURE. Readers are referred to Sect. M9 of the SCALE document for details on MARS and to Sect. M13 of the SCALE document for details on PICTURE.

Emmett, M.B.

1985-04-01

426

Thermal Conductivity of Liquid He-4 near the Superfluid Transition in Restricted Geometries

NASA Technical Reports Server (NTRS)

We present measurements of the thermal conductivity near the superfluid transition of He-4 in confined geometries. The confinements we have studied include: cylindrical geometries with radii L=.5 and 1.0 microns, and parallel plates with 5 micron spacing. For L=1.0 microns, measurements at six pressures were conducted, whereas only SVP measurements have been done for other geometries. For the 1-D confinement in cylinders, the data are consistent with a universal scaling for all pressures at and above T(sub lambda). There are indications of breakdown of scaling and universality below T(sub lambda). For the 2-D confinement between parallel plates, the preliminary results indicate that the thermal conductivity is finite at the bulk superfluid transition temperature. Further analyses are needed to compare the 2-D results with those in bulk and 1-D confinement.

Liu, Yuanming

2003-01-01

427

3D surface configuration modulates 2D symmetry detection.

We investigated whether three-dimensional (3D) information in a scene can affect symmetry detection. The stimuli were random dot patterns with 15% dot density. We measured the coherence threshold, or the proportion of dots that were the mirror reflection of the other dots in the other half of the image about a central vertical axis, at 75% accuracy with a 2AFC paradigm under various 3D configurations produced by the disparity between the left and right eye images. The results showed that symmetry detection was difficult when the corresponding dots across the symmetry axis were on different frontoparallel or inclined planes. However, this effect was not due to a difference in distance, as the observers could detect symmetry on a slanted surface, where the depth of the two sides of the symmetric axis was different. The threshold was reduced for a hinge configuration where the join of two slanted surfaces coincided with the axis of symmetry. Our result suggests that the detection of two-dimensional (2D) symmetry patterns is subject to the 3D configuration of the scene; and that coplanarity across the symmetry axis and consistency between the 2D pattern and 3D structure are important factors for symmetry detection. PMID:25536469

Chen, Chien-Chung; Sio, Lok-Teng

2015-02-01

428

2D Mueller matrix approach for tissue complete polarization characterization

NASA Astrophysics Data System (ADS)

The use of optical techniques in medical praxis allows practitioners to improve their tools. This improvement is realized in two main aspects, treatment and characterization of biological tissue. The former deals with methods like Photodynamic Therapy (PDT), Low Intensity Laser Therapy (LILT) or Hyperthermia. Tissue characterization by optical means is more challenging. The idea is to obtain images from biological tissues with a non-contact, non-invasive and safe procedure. The drawbacks of conventional imaging techniques, like X-Ray with its ionising radiation or ultrasound with the needed contact, are then avoided. Some of these optical techniques are for instance Confocal Microscopy or Optical Coherence Tomography (OCT). The inclusion of the analysis of light polarization can increase the contrast in these images. In this work, polarization information via the Mueller matrix of the target tissue in 2D is proposed as an improved way of characterization. This matrix contains all the polarization properties of tissue, including depolarisation, so a more complete analysis can be carried out. A polarimeter, composed by linear polarizers and rotators, as long as a CCD camera, is proposed to measure 2D Mueller matrix in concrete points of a biological tissue. The importance of these diagnosis methods is crucial in preliminary detection of diseases, like cancer.

Fanjul-Vélez, F.; Arce-Diego, J.-L.; Romanov, O. G.; Tolstik, A. L.; Ormachea, O.

2007-06-01

429

Meshfree natural vibration analysis of 2D structures

NASA Astrophysics Data System (ADS)

Determination of resonance frequencies and vibration modes of mechanical structures is one of the most important tasks in the product design procedure. The main goal of this paper is to describe a pioneering application of the solution structure method (SSM) to 2D structural natural vibration analysis problems and investigate the numerical properties of the method. SSM is a meshfree method which enables construction of the solutions to the engineering problems that satisfy exactly all prescribed boundary conditions. This method is capable of using spatial meshes that do not conform to the shape of a geometric model. Instead of using the grid nodes to enforce boundary conditions, it employs distance fields to the geometric boundaries and combines them with the basis functions and prescribed boundary conditions at run time. This defines unprecedented geometric flexibility of the SSM as well as the complete automation of the solution procedure. In the paper we will explain the key points of the SSM as well as investigate the accuracy and convergence of the proposed approach by comparing our results with the ones obtained using analytical methods or traditional finite element analysis. Despite in this paper we are dealing with 2D in-plane vibrations, the proposed approach has a straightforward generalization to model vibrations of 3D structures.

Kosta, Tomislav; Tsukanov, Igor

2014-02-01

430

Dynamics of quasi 2D co-rotating vortex merger

NASA Astrophysics Data System (ADS)

Merger of vortices is examined experimentally to compare the merger of slender parallel vortices generated coincidentally. It is known that like-sign vortices rotate around a common center of circulation and merger between the vortices may occur under certain conditions. This merger is dependent on the strength of the vortex circulation, distance of separation between the centers of the two vortices, ReGamma, and vorticity distribution. Quasi-2D experimental data is examined and merger relations are derived. The 2D experiments conducted in a vortex generator tank uses high aspect ratio rotating paddles. The vortex merger tank generates slender co-rotating vortices and are examined using PIV (Particle Image Velocimetry). Merger characteristics are compared at centerline, 25% span and 5% span for different circulation strengths. Symmetric and asymmetric mergers are studied and it is found that in both cases, the vortex pair rotates around an axis perpendicular to the plane of the vortex pair. Symmetric merger is seen to occur at the center between the two vortices whereas in asymmetric merger the stronger vortex breaks the weaker vortex filaments and continues to follow its path. Wall effects seem to have an effect of vortex braiding and vortex stretching. Closer to the wall, the merger time increases while the merged vortex dissipates faster than at the centerline.

Khandekar, Akshay G.

431

Force chains and hysteresis in a 2D granular piston

NASA Astrophysics Data System (ADS)

We present photoelastic studies of force distributions and propagation in a 2D granular piston.footnote E. Kolb, et. al. Europhys. J. B. 8, 483-491 (1999). The particles, ~ 1/2 cm disks, are confined by rigid sidewalls and pushed against gravity by a piston at constant velocity in the range 10-150 ? m/s. Friction prevents the free rotation and displacement of particles within the bulk of the material and leads to the buildup of stress chains resisting motion. The local and global stress within the granular material can be extracted by placing the experiment between complimentary circular polarizers. We find that the initial preparation (where the particles rain down in bulk) gives a stress minimum in the middle and edges, while the stress is polarized and maximal along each sidewall. The 2D pressure saturates at a depth ~ 1/2 width, and uniform compressive loads show hysteresis within the bulk. Under shear, we present evidence of stick-slip dynamics and large-scale convection when the particles can mobilize after dilation.

Hartley, R. R.; Behringer, R. P.; Kolb, E.; Ovarlez, G.; Clement, E.

2001-11-01

432

Robust 2D topological insulators in van der Waals heterostructures.

We predict a family of robust two-dimensional (2D) topological insulators in van der Waals heterostructures comprising graphene and chalcogenides BiTeX (X = Cl, Br, and I). The layered structures of both constituent materials produce a naturally smooth interface that is conducive to proximity-induced topological states. First-principles calculations reveal intrinsic topologically nontrivial bulk energy gaps as large as 70-80 meV, which can be further enhanced up to 120 meV by compression. The strong spin-orbit coupling in BiTeX has a significant influence on the graphene Dirac states, resulting in the topologically nontrivial band structure, which is confirmed by calculated nontrivial Z2 index and an explicit demonstration of metallic edge states. Such heterostructures offer a unique Dirac transport system that combines the 2D Dirac states from graphene and 1D Dirac edge states from the topological insulator, and it offers ideas for innovative device designs. PMID:25226453

Kou, Liangzhi; Wu, Shu-Chun; Felser, Claudia; Frauenheim, Thomas; Chen, Changfeng; Yan, Binghai

2014-10-28

433

2D NMR-spectroscopic screening reveals polyketides in ladybugs.

Small molecules of biological origin continue to yield the most promising leads for drug design, but systematic approaches for exploring nature's cache of structural diversity are lacking. Here, we demonstrate the use of 2D NMR spectroscopy to screen a library of biorationally selected insect metabolite samples for partial structures indicating the presence of new chemical entities. This NMR-spectroscopic survey enabled detection of novel compounds in complex metabolite mixtures without prior fractionation or isolation. Our screen led to discovery and subsequent isolation of two families of tricyclic pyrones in Delphastus catalinae, a tiny ladybird beetle that is employed commercially as a biological pest control agent. The D. catalinae pyrones are based on 23-carbon polyketide chains forming 1,11-dioxo-2,6,10-trioxaanthracene and 4,8-dioxo-1,9,13-trioxaanthracene derivatives, representing ring systems not previously found in nature. This study highlights the utility of 2D NMR-spectroscopic screening for exploring nature's structure space and suggests that insect metabolomes remain vastly underexplored. PMID:21646540

Deyrup, Stephen T; Eckman, Laura E; McCarthy, Patrick H; Smedley, Scott R; Meinwald, Jerrold; Schroeder, Frank C

2011-06-14

434

2D Quantum Transport Modeling in Nanoscale MOSFETs

NASA Technical Reports Server (NTRS)

We have developed physical approximations and computer code capable of realistically simulating 2-D nanoscale transistors, using the non-equilibrium Green's function (NEGF) method. This is the most accurate full quantum model yet applied to 2-D device simulation. Open boundary conditions, oxide tunneling and phase-breaking scattering are treated on an equal footing. Electron bandstructure is treated within the anisotropic effective mass approximation. We present the results of our simulations of MIT 25 and 90 nm "well-tempered" MOSFETs and compare them to those of classical and quantum corrected models. The important feature of quantum model is smaller slope of Id-Vg curve and consequently higher threshold voltage. These results are consistent with 1D Schroedinger-Poisson calculations. The effect of gate length on gate-oxide leakage and subthreshold current has been studied. The shorter gate length device has an order of magnitude smaller leakage current than the longer gate length device without a significant trade-off in on-current.

Svizhenko, Alexei; Anantram, M. P.; Govindan, T. R.; Biegel, B.

2001-01-01

435

New Approach for 2D Readout of GEM Detectors

Detectors based on Gas Electron Multiplication (GEM) technology are becoming more and more widely used in nuclear and high energy physics and are being applied in astronomy, medical physics, industry, and homeland security. GEM detectors are thin, low mass, insensitive to magnetic fields, and can currently provide position resolutions down to {approx}50 microns. However, the designs for reconstructing the position, in two dimensions (2D), of the charged particles striking a GEM detector are often complicated to fabricate and expensive. The objective of this proposal is to investigate a simpler procedure for producing the two dimensional readout layer of GEM detectors using readily available printed circuit board technology which can be tailored to the detector requirements. We will use the established GEM laboratory and facilities at M.I.T. currently employed in developing GEM detectors for the STAR forward tracking upgrade to simplify the testing and evaluation of the new 2D readout designs. If this new design proves successful it will benefit future nuclear and high energy physics experiments already being planned and will similarly extend and simplify the application of GEM technology to other branches of science, medicine, and industry. These benefits would be not only in lower costs for fabrication but also it increased flexibility for design and application.

Hasell, Douglas K

2011-10-29

436

Hamiltonian Operators of Dubrovin-Novikov Type in 2D

NASA Astrophysics Data System (ADS)

First order Hamiltonian operators of differential-geometric type were introduced by Dubrovin and Novikov in 1983, and thoroughly investigated by Mokhov. In 2D, they are generated by a pair of compatible flat metrics {g} and {tilde g} which satisfy a set of additional constraints coming from the skew-symmetry condition and the Jacobi identity. We demonstrate that these constraints are equivalent to the requirement that {tilde g} is a linear Killing tensor of g with zero Nijenhuis torsion. This allowed us to obtain a complete classification of n-component operators with n ? 4 (for n = 1, 2 this was done before). For 2D operators the Darboux theorem does not hold: the operator may not be reducible to constant coefficient form. All interesting (non-constant) examples correspond to the case when the flat pencil {g, tilde g} is not semisimple, that is, the affinor {tilde g g^{-1}} has non-trivial Jordan block structure. In the case of a direct sum of Jordan blocks with distinct eigenvalues, we obtain a complete classification of Hamiltonian operators for any number of components n, revealing a remarkable correspondence with the class of trivial Frobenius manifolds modelled on H *(CP n-1).

Ferapontov, Evgeny V.; Lorenzoni, Paolo; Savoldi, Andrea

2014-12-01

437

The effects of aging on haptic 2D shape recognition.

We use the image-mediation model (Klatzky & Lederman, 1987) as a framework to investigate potential sources of adult age differences in the haptic recognition of two-dimensional (2D) shapes. This model states that the low-resolution, temporally sequential, haptic input is translated into a visual image, which is then reperceived through the visual processors, before it is matched against a long-term memory representation and named. In three experiments we tested groups of 12 older (mean age 73.11) and three groups of 12 young adults (mean age 22.80) each. In Experiment 1 we confirm age-related differences in haptic 2D shape recognition, and we show the typical age × complexity interaction. In Experiment 2 we show that if we facilitate the visual translation process, age differences become smaller, but only with simple shapes and not with the more complex everyday objects. In Experiment 3 we target the last step in the model (matching and naming) for complex stimuli. We found that age differences in exploration time were considerably reduced when this component process was facilitated by providing a category name. We conclude that the image-mediation model can explain adult-age differences in haptic recognition, particularly if the role of working memory in forming the transient visual image is considered. Our findings suggest that sensorimotor skills thought to rely on peripheral processes for the most part are critically constrained by age-related changes in central processing capacity in later adulthood. PMID:23978010

Overvliet, Krista E; Wagemans, J; Krampe, Ralf T

2013-12-01

438

Small-Space 2D Compressed Dictionary Matching

NASA Astrophysics Data System (ADS)

The dictionary matching problem seeks all locations in a text that match any of the patterns in a dictionary. In the compressed dictionary matching problem, the input is in compressed form. In this paper we introduce the 2-dimensional compressed dictionary matching problem in Lempel-Ziv compressed images, and present an efficient solution for patterns whose rows are all periodic. Given k patterns, each of (uncompressed) size m ×m, and a text of (uncompressed) size n ×n, all in 2D-LZ compressed form, our algorithm finds all occurrences of the patterns in the text. The algorithm is strongly inplace, i.e., the extra space it uses is proportional to the optimal compression of the dictionary, which is O(km). The preprocessing time of the algorithm is O(km 2), linear in the uncompressed dictionary size, and the time for performing the search is linear in the uncompressed text size, independent of the dictionary size. Our algorithm is general in the sense that it can be used for any 2D compression scheme which can be sequentially decompressed in small space.

Neuburger, Shoshana; Sokol, Dina

439

Predicting abnormal pressure from 2-D seismic velocity modeling

Seismic velocities are the only data available, before drilling, on which to base a quantitative, present-day estimate of abnormal pressure. Recent advances in seismic velocity processing have enabled them to obtain, using an in-house approach, an optimized 2-D interval velocity field and consequently to better define the lateral extension of pressure regimes. The methodology, interpretation and quantification of overpressure-related anomalies are supported by case studies, selected in sand-shale dominated Tertiary basins, offshore West Africa. Another advantage of this approach is that it can also account for the presence of reservoir-potential intervals at great depth and thus provide significant insight, from a prospective standpoint, into very poorly explored areas. Although at the outset the 2-D seismic tool legitimately merits being favored, optimization of the final predictive pressure model, prior to drilling, will depend upon the success of its combined use with other concepts and approaches, pertaining to structural geology, sedimentology, rock mechanics and fluid dynamics.

Grauls, D.; Dunand, J.P.; Beaufort, D.

1995-12-01

440

2D NMR-spectroscopic screening reveals polyketides in ladybugs

Small molecules of biological origin continue to yield the most promising leads for drug design, but systematic approaches for exploring nature’s cache of structural diversity are lacking. Here, we demonstrate the use of 2D NMR spectroscopy to screen a library of biorationally selected insect metabolite samples for partial structures indicating the presence of new chemical entities. This NMR-spectroscopic survey enabled detection of novel compounds in complex metabolite mixtures without prior fractionation or isolation. Our screen led to discovery and subsequent isolation of two families of tricyclic pyrones in Delphastus catalinae, a tiny ladybird beetle that is employed commercially as a biological pest control agent. The D. catalinae pyrones are based on 23-carbon polyketide chains forming 1,11-dioxo-2,6,10-trioxaanthracene and 4,8-dioxo-1,9,13-trioxaanthracene derivatives, representing ring systems not previously found in nature. This study highlights the utility of 2D NMR-spectroscopic screening for exploring nature’s structure space and suggests that insect metabolomes remain vastly underexplored. PMID:21646540

Deyrup, Stephen T.; Eckman, Laura E.; McCarthy, Patrick H.; Smedley, Scott R.; Meinwald, Jerrold; Schroeder, Frank C.

2011-01-01

441

MESH2D GRID GENERATOR DESIGN AND USE

Mesh2d is a Fortran90 program designed to generate two-dimensional structured grids of the form [x(i),y(i,j)] where [x,y] are grid coordinates identified by indices (i,j). The x(i) coordinates alone can be used to specify a one-dimensional grid. Because the x-coordinates vary only with the i index, a two-dimensional grid is composed in part of straight vertical lines. However, the nominally horizontal y(i,j{sub 0}) coordinates along index i are permitted to undulate or otherwise vary. Mesh2d also assigns an integer material type to each grid cell, mtyp(i,j), in a user-specified manner. The complete grid is specified through three separate input files defining the x(i), y(i,j), and mtyp(i,j) variations. The overall mesh is constructed from grid zones that are typically then subdivided into a collection of smaller grid cells. The grid zones usually correspond to distinct materials or larger-scale geometric shapes. The structured grid zones are identified through uppercase indices (I,J). Subdivision of zonal regions into grid cells can be done uniformly, or nonuniformly using either a polynomial or geometric skewing algorithm. Grid cells may be concentrated backward, forward, or toward both ends. Figure 1 illustrates the above concepts in the context of a simple four zone grid.

Flach, G.; Smith, F.

2012-01-20

442

Rejuvenation and memory in a 2D colloidal glass

NASA Astrophysics Data System (ADS)

We work with a 2D colloidal system that has a glass transition and use this system to experimentally observe memory and rejuvenation effects as the sample ages. In particular, we study a system of colloidal particles made of thermosensitive poly(N-isopropylacrylamide) (NIPA) polymer. The sample is confined in a narrow quasi-2D gap between parallel glass plates, which allows easy observation and rapid temperature response. Lowering temperature increases the size of the colloidal particles, which can induce the glassy state due to the crowding of the particles. When our colloidal sample is quenched into the glassy state, particle motion slows over time; this is aging. In molecular glasses, prior experiments studied how aging is modified when the temperature is changed while the sample ages, finding that aging at a first temperature T1 and aging at a later time with second temperature T2 are mostly independent. ``Memory'' relates to the case T1< T2 and "rejuvenation" to the opposite case. Our colloidal system allows us to observe both of these effects.

Lynch, Jennifer M.; Zhang, Zexin; Yunker, Peter; Yodh, Arjun G.; Weeks, Eric R.

2009-03-01

443

AXIOMATIC AND COORDINATE GEOMETRY KAPIL PARANJAPE

analytic) geometry. Later, during gradu* *ate studies we are introduced to differential geometry of many AXIOMATIC AND COORDINATE GEOMETRY KAPIL and college we first make the transition b* *etween Euclidean (or synthetic) geometry and co-ordinate (or

Paranjape, Kapil

444

18 8 2007 8 2007-18-8-19 Performance Improvement for 2-D Scattering Center Extraction and

Transform) . . . 2 ISAR 2-D MEMP 2-D ESPRIT . F-18 2 and F-18 aircraft to estimate 2-D scattering center and abtain 2-D ISAR image. Key words : Scattering 2-D MEMP, 2-D ESPRIT . 2 ISAR 2 , . 2 , F-18 2

Myung, Noh-Hoon

445

While the study of geometry has mainly concentrated on single-viewpoint (SVP) cameras, there is growing attention to more general non-SVP systems. Here we study an important class of systems that inherently have a non-SVP: a perspective camera imaging through an interface into a medium. Such systems are ubiquitous: they are common when looking into water-based environments. The paper analyzes the common flat-interface class of systems. It characterizes the locus of the viewpoints (caustic) of this class, and proves that the SVP model is invalid in it. This may explain geometrical errors encountered in prior studies. Our physics-based model is parameterized by the distance of the lens from the medium interface, beside the focal length. The physical parameters are calibrated by a simple approach that can be based on a single-frame. This directly determines the system geometry. The calibration is then used to compensate for modeled system distortion. Based on this model, geometrical measurements of objects are significantly more accurate, than if based on an SVP model. This is demonstrated in real-world experiments. In addition, we examine by simulation the errors expected by using the SVP model. We show that when working at a constant range, the SVP model can be a good approximation. PMID:21576744

Treibitz, Tali; Schechner, Yoav; Kunz, Clayton; Singh, Hanumant

2011-05-13

446

Involutes: the geometry of chemical waves rotating in annular membranes.

According to earlier theories certain parts of a chemical wave front propagating in a 2-D excitable medium with a convex obstacle should be involutes of that obstacle. The present paper discusses a special case where self-sustained chemical waves are rotating around a central obstacle in an annular 2-D excitable region. A simple geometrical model of wave propagation based on the Fermat principle (minimum propagation time) is suggested. Applying this model it is shown that the wave fronts in the case of an annular excitable region should be purely involutes of the central obstacle in the asymptotic state. This theory is supported by experiments in a novel membrane reactor where a catalyst of the Belousov-Zhabotinsky reaction is fixed on a porous membrane combined with a gel medium. Involutes of circular and triangular obstacles are observed experimentally. Deviations from the ideal involute geometry are explained by inhomogeneities in the membrane. (c) 1995 American Institute of Physics. PMID:12780199

Lazar, Attila; Noszticzius, Zoltan; Farkas, Henrik; Forsterling, Horst-Dieter

1995-06-01

447

Rapid multi-wave-type ray tracing in complex 2-D and 3-D isotropic media

The authors describe a method for seismic ray tracing in complex 2-D and 3-D heterogeneous isotropic media. Both the interface geometry and the horizontal velocity field are parameterized by using nonuniformly spaced cubic B-spline nodes. In particular, they present a modified cubic B-spline method for modeling discontinuities. This model parameterization scheme facilitates tomographic inversion of traveltimes and can represent any realistic geological structure that is continuously varying with embedded discontinuities. Many wave types, such as transmitted, reflected, refracted, mode-converted, diffracted, and turning waves, are desirable for complex geological models. They select rays of various wave types by choice of initial paths and refine them by applying Fermat`s minimum time principle. Since the raypath is piecewise linear between interfaces, they solve a system of linearized equations by iteration to produce the actual raypath between source and receiver. The method is fast and unifies the ray-tracing procedure for various wave types and multiple paths between a source-receiver pair. Ray amplitudes can be also evaluated by existing analytical formulae. Several examples show that the method is computationally accurate and effective. The method is practicable for multiphase traveltime tomography and 3-D ray-trace seismic modeling.

Mao, W.; Stuart, G.W. [Univ. of Leeds (United Kingdom). Dept. of Earth Sciences] [Univ. of Leeds (United Kingdom). Dept. of Earth Sciences

1997-01-01

448

PRONTO 2D: A two-dimensional transient solid dynamics program

PRONTO 2D is a two-dimensional transient solid dynamics code for analyzing large deformations of highly nonlinear materials subjected to extremely high strain rates. This Lagrangian finite element program uses an explicit time integration operator to integrate the equations of motion. Four node uniform strain quadrilateral elements are used in the finite element formulation. A number of new numerical algorithms which have been developed for the code are described in this report. An adaptive time step control algorithm is described which greatly improves stability as well as performance in plasticity problems. A robust hourglass control scheme which eliminates hourglass distortions without disturbing the finite element solution is included. All constitutive models in PRONTO are cast in an unrotated configuration defined using the rotation determined from the polar decomposition of the deformation gradient. An accurate incremental algorithm was developed to determine this rotation and is described in detail. A robust contact algorithm was developed which allows for the impact and interaction of deforming contact surfaces of quite general geometry. A number of numerical examples are presented to demonstrate the utility of these algorithms. 41 refs., 51 figs., 5 tabs.

Taylor, L.M.; Flanagan, D.P.

1987-03-01

449

2D photonic crystal complete band gap search using a cyclic cellular automaton refination

NASA Astrophysics Data System (ADS)

We present a refination method based on a cyclic cellular automaton (CCA) that simulates a crystallization-like process, aided with a heuristic evolutionary method called differential evolution (DE) used to perform an ordered search of full photonic band gaps (FPBGs) in a 2D photonic crystal (PC). The solution is proposed as a combinatorial optimization of the elements in a binary array. These elements represent the existence or absence of a dielectric material surrounded by air, thus representing a general geometry whose search space is defined by the number of elements in such array. A block-iterative frequency-domain method was used to compute the FPBGs on a PC, when present. DE has proved to be useful in combinatorial problems and we also present an implementation feature that takes advantage of the periodic nature of PCs to enhance the convergence of this algorithm. Finally, we used this methodology to find a PC structure with a 19% bandgap-to-midgap ratio without requiring previous information of suboptimal configurations and we made a statistical study of how it is affected by disorder in the borders of the structure compared with a previous work that uses a genetic algorithm.

González-García, R.; Castañón, G.; Hernández-Figueroa, H. E.

2014-11-01

450

2D Simulations of KSTAR edge plasma using SOLPS 4.3 code

NASA Astrophysics Data System (ADS)

Control of plasma density and impurity content is crucial to achieve high performance long pulse operation in tokamaks. In this paper edge plasma scenarios of KSTAR are analyzed numerically. ITER version of the well-known SOLPS code package (SOLPS4.3) which comprises 2D multi-species fluid plasma code B2 and 3D Monte-Carlo particle solver EIRENE coupled self-consistently. This latter allows full kinetic neutral particle transport modeling in realistic geometries including pump ducts and leaks to the main vessel from the sub-divertor volumes. Both connected and disconnected double null configurations are investigated. The main focus is made on studying the sensitivity of the edge plasma parameters with respect to gas puffing rate (density scans), thus, effectiveness of this latter for the plasma control. Preliminary findings show that for the reference KSTAR pumps: total pumping speed 100 m^3/s, pumping rates up to 13 Pa.m^3/s, and high performance discharges with heating power 8 MW plasma in both divertors is likely to stay attached. At the same time, plasma temperature at the divertor targets as well as the peak incident heat flux density can be effectively reduced with increased gas puff, been especially sensitive in the inner divertors.

Shim, Seung Bo; Kotov, Vladislav; Reiter, Detelev; Han, Hyunsun; Kim, Jin Yong; Na, Yong-Su; Lee, Hae June

2012-10-01

451

Photoacoustic imaging for deep targets in the breast using a multichannel 2D array transducer

NASA Astrophysics Data System (ADS)

A photoacoustic (PA) imaging system was developed to achieve high sensitivity for the detection and characterization of vascular anomalies in the breast in the mammographic geometry. Signal detection from deep in the breast was achieved by a broadband 2D PVDF planar array that has a round shape with one side trimmed straight to improve fit near the chest wall. This array has 572 active elements and a -6dB bandwidth of 0.6-1.7 MHz. The low frequency enhances imaging depth and increases the size of vascular collections displayed without edge enhancement. The PA signals from all the elements go through low noise preamplifiers in the probe that are very close to the array elements for optimized noise control. Driven by 20 independent on-probe signal processing channels, imaging with both high sensitivity and good speed was achieved. To evaluate the imaging depth and the spatial resolution of this system,2.38mm I.D. artificial vessels embedded deeply in ex vivo breasts harvested from fresh cadavers and a 3mm I.D. tube in breast mimicking phantoms made of pork loin and fat tissues were imaged. Using near-infrared laser light with incident energy density within the ANSI safety limit, imaging depths of up to 49 mm in human breasts and 52 mm in phantoms were achieved. With a high power tunable laser working on multiple wavelengths, this system might contribute to 3D noninvasive imaging of morphological and physiological tissue features throughout the breast.

Xie, Zhixing; Wang, Xueding; Morris, Richard F.; Padilla, Frederic R.; Lecarpentier, Gerald L.; Carson, Paul L.

2011-03-01

452

Learning Geometry in Georgian England

NSDL National Science Digital Library

How did people learn geometry in Georgian England? It was different than in our own time, to be sure. This feature from Loci, the online publication of the MAA Mathematical Sciences Digital Library offers a bit of detail on the matter, courtesy of the geometry copybook of a boy named Thomas Porcher. This particular feature was written by Benjamin Wardhaugh from the University of Oxford. In the six-part feature, Wardhaugh looks into why such a boy would learn geometry and also what the existing texts were at the time. The article contains sections like "Geometry and Measuring" and "Geometry and Practical Geometry." It's a fascinating study, and one that will be intriguing to those with a penchant for the history of mathematics and pedagogy.

Porcher, Thomas; Wardhaugh, Benjamin, 1979-

2012-09-21

453

Geometric Modeling and Industrial Geometry

NSDL National Science Digital Library

The Geometric Modeling and Industrial Geometry group is part of the Institute of Discrete Mathematics and Geometry at the Vienna University of Technology. The group's goal is "to bridge the gap between academic and industrial research in geometry" by "performing application oriented fundamental research and industrial research closely connected to geometry." Its work currently emphasizes the recognition, inspection, manipulation, and design of geometric shapes. Short descriptions of the group's work and some articles are available on the academic research, covering topics such as Computational Line Geometry, Laguerre Geometry, approximation in the space of planes, the isophotic metric, and swept volumes. Visitors can also read about the group's industrial research on 3-D Computer Vision, reverse Engineering, and Industrial Inspection. The Application Areas section includes more articles and provides actual data from some of the objects it has scanned along with the resulting 3-D images.

454

A 2-D Test Problem for CFD Modeling Heat Transfer in Spent Fuel Transfer Cask Neutron Shields

In the United States, commercial spent nuclear fuel is typically moved from spent fuel pools to outdoor dry storage pads within a transfer cask system that provides radiation shielding to protect personnel and the surrounding environment. The transfer casks are cylindrical steel enclosures with integral gamma and neutron radiation shields. Since the transfer cask system must be passively cooled, decay heat removal from spent nuclear fuel canister is limited by the rate of heat transfer through the cask components, and natural convection from the transfer cask surface. The primary mode of heat transfer within the transfer cask system is conduction, but some cask designs incorporate a liquid neutron shield tank surrounding the transfer cask structural shell. In these systems, accurate prediction of natural convection within the neutron shield tank is an important part of assessing the overall thermal performance of the transfer cask system. The large-scale geometry of the neutron shield tank, which is typically an annulus approximately 2 meters in diameter but only 5-10 cm in thickness, and the relatively small scale velocities (typically less than 5 cm/s) represent a wide range of spatial and temporal scales that contribute to making this a challenging problem for computational fluid dynamics (CFD) modeling. Relevant experimental data at these scales are not available in the literature, but some recent modeling studies offer insights into numerical issues and solutions; however, the geometries in these studies, and for the experimental data in the literature at smaller scales, all have large annular gaps that are not prototypic of the transfer cask neutron shield. This paper presents results for a simple 2-D problem that is an effective numerical analog for the neutron shield application. Because it is 2-D, solutions can be obtained relatively quickly allowing a comparison and assessment of sensitivity to model parameter changes. Turbulence models are considered as well as the tradeoff between steady state and transient solutions. Solutions are compared for two commercial CFD codes, FLUENT and STAR-CCM+. The results can be used to provide input to the CFD Best Practices for this application. Following study results for the 2-D test problem, a comparison of simulation results is provided for a high Rayleigh number experiment with large annular gap. Because the geometry of this validation is significantly different from the neutron shield, and due to the critical nature of this application, the argument is made for new experiments at representative scales

Zigh, Ghani; Solis, Jorge; Fort, James A.

2011-01-14

455

Advanced geometries and regimes

NASA Astrophysics Data System (ADS)

We review and discuss different schemes of laser ion acceleration as well as advanced target geometries in connection with the development of the laser-driven proton source for hadron therapy of oncological diseases, which is a part of the ELIMED project. At the request of the Proceedings Editors and Dr. Stepan Bulanov, University of California, Berkeley, the above article has been updated to include three additional authors: A. Stockem, F. Fiuza, and L. O. Silva. All additional authors have consented to their name being added to the paper. Furthermore, the updated article PDF contains amendments to a number of references as detailed within the pages attached to the end of the updated article PDF file. The updated article was re-published on 8 August 2013.

Bulanov, S. S.; Bulanov, S. V.; Turchetti, G.; Limpouch, J.; Klimo, O.; Psikal, J.; Stockem, A.; Fiuza, F.; Silva, L. O.; Antici, P.; Margarone, D.; Korn, G.

2013-08-01

456

In these Notes, a comprehensive description of the universal fractal geometry of conformally-invariant scaling curves or interfaces, in the plane or half-plane, is given. The present approach focuses on deriving critical exponents associated with interacting random paths, by exploiting their underlying quantum gravity structure. The latter relates exponents in the plane to those on a random lattice, i.e., in a fluctuating metric, using the so-called Knizhnik, Polyakov and Zamolodchikov (KPZ) map. This is accomplished within the framework of random matrix theory and conformal field theory, with applications to geometrical critical models, like Brownian paths, self-avoiding walks, percolation, and more generally, the O(N) or Q-state Potts models and, last but not least, Schramm's Stochastic Loewner Evolution (SLE_kappa). These Notes can be considered as complementary to those by Wendelin Werner (2006 Fields Medalist!), ``Some Recent Aspects of Random Conformally Invariant Systems,'' arXiv:math.PR/0511268.

Bertrand Duplantier

2006-08-23

457

Critique of information geometry

NASA Astrophysics Data System (ADS)

As applied to probability, information geometry fails because probability distributions do not form a metric space. Probability theory rests on a compelling foundation of elementary symmetries, which also support information (aka minus entropy, Kullback-Leibler) H(p;q) as the unique measure of divergence from source probability distribution q to destination p. Because the only compatible connective H is from?to asymmetric, H(p;q)?H(q;p), there can be no compatible geometrical distance (which would necessarily be from=to symmetric). Hence there is no distance relationship compatible with the structure of probability theory. Metrics g and densities sqrt(det(g)) interpreted as prior probabilities follow from the definition of distance, and must fail likewise. Various metrics and corresponding priors have been proposed, Fisher's being the most popular, but all must behave unacceptably. This is illustrated with simple counter-examples.

Skilling, John

2014-12-01

458

Universal Hyperbolic Geometry I: Trigonometry

Hyperbolic geometry is developed in a purely algebraic fashion from first\\u000aprinciples, without a prior development of differential geometry. The natural\\u000aconnection with the geometry of Lorentz, Einstein and Minkowski comes from a\\u000aprojective point of view, with trigonometric laws that extend to `points at\\u000ainfinity', here called `null points', and beyond to `ideal points' associated\\u000ato a hyperboloid of

N. J. Wildberger

2009-01-01

459

The Geometry of Homological Triangles

This book is addressed to students, professors and researchers of geometry, who will find herein many interesting and original results. The originality of the book The Geometry of Homological Triangles consists in using the homology of triangles as a "filter" through which remarkable notions and theorems from the geometry of the triangle are unitarily passed. Our research is structured in seven chapters, the first four are dedicated to the homology of the triangles, while the last ones to their applications.

Florentin Smarandache; Ion Patrascu

2012-04-07

460

New developments in special geometry

We review recent developments in special geometry, emphasizing the role of real coordinates. In the first part we discuss the para-complex geometry of vector and hypermultiplets in rigid Euclidean N=2 supersymmetry. In the second part we study the variational principle governing the near horizon limit of BPS black holes in matter-coupled N=2 supergravity and observe that the black hole entropy is the Legendre transform of the Hesse potential encoding the geometry of the scalar fields.

Thomas Mohaupt

2006-02-17

461

The geometry package Hideo UMEKI

The geometry package Hideo UMEKI hideo.umeki@toshiba.co.jp 2002/07/08 v3.2 Abstract This package and bottom margins) to 2cm from each edge of the paper, what you need is just \\usepackage[margin=2cm]{geometry}. Contents 1 Preface to Version 3 1 2 Introduction 2 3 Page Geometry 3 3.1 Layout Dimensions . . . . . . . 3

Mintmire, John W.

462

areaDetector: Software for 2-D Detectors in EPICS

areaDetector is a new EPICS module designed to support 2-D detectors. It is modular C++ code that greatly simplifies the task of writing support for a new detector. It also supports plugins, which receive detector data from the driver and process it in some way. Existing plugins perform Region-Of-Interest extraction and analysis, file saving (in netCDF, HDF, TIFF and JPEG formats), color conversion, and export to EPICS records for image display in clients like ImageJ and IDL. Drivers have now been written for many of the detectors commonly used at synchrotron beamlines, including CCDs, pixel array and amorphous silicon detectors, and online image plates.

Rivers, Mark L. [Center for Advanced Radiation Sources and Department of Geophysical Sciences, University of Chicago, Argonne, IL 60439 (United States)

2010-06-23

463

Force-chain identification in quasi-2D granular systems

NASA Astrophysics Data System (ADS)

Understanding the properties of force-chains is essential in understanding the physical and mechanical properties of granular materials. The key is to identify force-chains. In this study, we describe a systematic method to identify individual force-chains in 2D granular systems under different external load-pure shear or isotropic compression, where bi-disperse photo-elastic particles were used in order to measure vector contact forces between particles. Using this method, we studied the statistics of force-chain size distribution in these two systems: in pure shear, the distribution shows a fat tail that deviates from an exponential distribution function, whereas in isotropic compression, the distribution decays exponentially. In addition, we also investigated the dependence of various force-chain statistics on two main parameters defined in the force-chain identification algorithm.

Zhang, Ling; Wu, Jun-Qi; Zhang, Jie

2013-06-01

464

Quantum anomalous Hall effect in 2D organic topological insulators.

The quantum anomalous Hall effect (QAHE) is a fundamental transport phenomenon in the field of condensed-matter physics. Without an external magnetic field, spontaneous magnetization combined with spin-orbit coupling gives rise to a quantized Hall conductivity. So far, a number of theoretical proposals have been made to realize the QAHE, but all based on inorganic materials. Here, using first-principles calculations, we predict a family of 2D organic topological insulators for realizing the QAHE. Designed by assembling molecular building blocks of triphenyl-transition-metal compounds into a hexagonal lattice, this new class of organic materials is shown to have a nonzero Chern number and exhibits a gapless chiral edge state within the Dirac gap. PMID:23705732

Wang, Z F; Liu, Zheng; Liu, Feng

2013-05-10

465

TOPAZ2D validation status report, August 1990

Analytic solutions to two heat transfer problems were used to partially evaluate the performance TOPAZ, and LLNL finite element heat transfer code. The two benchmark analytic solutions were for: 2D steady state slab, with constant properties, constant uniform temperature boundary conditions on three sides, and constant temperature distribution according to a sine function on the fourth side; 1D transient non-linear, with temperature dependent conductivity and specific heat (varying such that the thermal diffusivity remained constant), constant heat flux on the front face and adiabatic conditions on the other face. The TOPAZ solution converged to the analytic solution in both the transient and the steady state problem. Consistent mass matrix type of analysis yielded best performance for the transient problem, in the late-time response; but notable unnatural anomalies were observed in the early-time temperature response at nodal locations near the front face. 5 refs., 22 figs.

Davis, B.

1990-08-01

466

Experimental Identification of Diffusive Coupling Using 2D NMR.

Spin relaxation based nuclear magnetic resonance (NMR) methods have been used extensively to determine pore size distributions in a variety of materials. This approach is based on the assumption that each pore is in the fast diffusion limit but that diffusion between pores can be neglected. However, in complex materials these assumptions may be violated and the relaxation time distribution is not easily interpreted. We present a 2D NMR technique and an associated data analysis that allow us to work directly with the time dependent experimental data without Laplace inversion to identify the signature of diffusive coupling between different pores. Measurements on microporous glass beads and numerical simulations are used to illustrate the technique. PMID:25526135

Song, Y-Q; Carneiro, G; Schwartz, L M; Johnson, D L

2014-12-01

467

Electrical spin injection in 2D semiconductors and topological insulators

We have developed a theory of spin orientation by electric current in 2D semiconductors. It is shown that the spin depends on the relation between the energy and spin relaxation times and can vary by a factor of two for the limiting cases of fast and slow energy relaxation. For symmetrically-doped (110)-grown semiconductor quantum wells the effect of current-induced spin orientation is shown to exist due to random spatial variation of the Rashba spin-orbit splitting. We demonstrate that the spin depends strongly on the correlation length of this random spin-orbit field. We calculate the spin orientation degree in two-dimensional topological insulators. In high electric fields when the “streaming” regime is realized, the spin orientation degree weakly depends on the electric field and can reach values about 5%.

Golub, L. E.; Ivchenko, E. L. [Ioffe Physical-Technical Institute of the Russian Academy of Sciences, St. Petersburg (Russian Federation)

2013-12-04

468

Automated Motion Estimation for 2D Cine DENSE MRI

Cine displacement encoding with stimulated echoes (DENSE) is a magnetic resonance (MR) method that directly encodes tissue displacement into MR phase images. This technique has successfully interrogated many forms of tissue motion, but is most commonly used to evaluate cardiac mechanics. Currently, motion analysis from cine DENSE images requires manually delineated anatomical structures. An automated analysis would improve measurement throughput, simplify data interpretation, and potentially access important physiological information during the MR exam. In this article, we present the first fully automated solution for the estimation of tissue motion and strain from 2D cine DENSE data. Results using both simulated and human cardiac cine DENSE data indicate good agreement between the automated algorithm and the standard semi-manual analysis method. PMID:22575669

Gilliam, Andrew D.; Epstein, Frederick H.

2013-01-01

469

Mesh model 2D reconstruction operator for SPECT

NASA Astrophysics Data System (ADS)

In this paper we extend our previous evaluation of 2D tomographic image reconstruction using a content-adaptive mesh model (CAMM) for emission tomography (EM). First we present a model for the projection operator calculation using a ray-tracing algorithm based on mesh modeling for image representation. The proposed calculation allows us to incorporate a non-uniform attenuation and distance-dependent spatial resolution of the imaging system. Next the proposed approach was tested using realistic simulations with the NCAT phantom and SIMIND Monte Carlo simulation of a SPECT system in which the mesh model is calculated using images from pre reconstruction by filtered-back projection. Thereby this paper establishes a necessary step for the future development of 3D reconstruction images and spatio-temporal processing using deformable mesh modeling.

Delgado Gonzalo, Ricard; Brankov, Jovan G.

2008-03-01

470

PZT-actuated, 2D optical scanning image acquisition

NASA Astrophysics Data System (ADS)

An image acquisition utilizing a 2D piezoelectric actuated optical scanner is presented. Fabrication and testing of a micromachined optically transmissive cantilever waveguide that operates in the resonant mode is presented with its application as a micro-optical scanner. The optical waveguide has a smaller cross-sectional area (2 µm × 5 µm) than our previous study (62.5 to 420 mm). The scanner is consisted of a single mode optical fiber (SMF28e) mounted on a X-Y coupled piezoelectric bimorphs operating at the actuators' resonant frequencies of 50 Hz and 128 Hz. The scanner achieves a 3.14 mm vertical and 0.61 mm horizontal tip displacements with a ±10V input.

Gu, Kebin; Lin, Keng-Ren; Wang, Wei-Chih

2014-04-01

471

Advecting Procedural Textures for 2D Flow Animation

NASA Technical Reports Server (NTRS)

This paper proposes the use of specially generated 3D procedural textures for visualizing steady state 2D flow fields. We use the flow field to advect and animate the texture over time. However, using standard texture advection techniques and arbitrary textures will introduce some undesirable effects such as: (a) expanding texture from a critical source point, (b) streaking pattern from the boundary of the flowfield, (c) crowding of advected textures near an attracting spiral or sink, and (d) absent or lack of textures in some regions of the flow. This paper proposes a number of strategies to solve these problems. We demonstrate how the technique works using both synthetic data and computational fluid dynamics data.

Kao, David; Pang, Alex; Moran, Pat (Technical Monitor)

2001-01-01

472

2D Microwave Imaging Reflectometry (MIR) in KSTAR

NASA Astrophysics Data System (ADS)

It is commonly believed that the small scale plasma turbulence is a key factor of enhancing the energy transport in magnetically confined plasmas. In order to verify the physical mechanism in KSTAR, turbulence measurement has been improved from a simple one-dimensional system to 2D-measurement to validate various theoretical models of the plasma turbulence. An advanced imaging diagnostic concept for electron density fluctuation measurement, microwave imaging reflectometry (MIR), overcomes the shortcomings of the conventional reflectometry. In this paper, a system description of the KSTAR MIR system, laboratory test results, and verification of the design specification with the known coherent oscillations in the core of the plasmas will be addressed. In addition, turbulence quantities such as cross phase analysis with the poloidal rotation velocity estimation will be presented as a preliminary analysis.

Leem, J.; Lee, W.; Kim, M.; Lee, J. A.; Nam, Y.; Yun, G. S.; Park, H. K.; Kim, Y. G.; Park, H.; Kim, K. W.; Domier, C. W.; Luhmann, N. C.

473

areaDetector: Software for 2-D Detectors in EPICS

areaDetector is a new EPICS module designed to support 2-D detectors. It is modular C++ code that greatly simplifies the task of writing support for a new detector. It also supports plugins, which receive detector data from the driver and process it in some way. Existing plugins perform Region-Of-Interest extraction and analysis, file saving (in netCDF, HDF, TIFF and JPEG formats), color conversion, and export to EPICS records for image display in clients like ImageJ and IDL. Drivers have now been written for many of the detectors commonly used at synchrotron beamlines, including CCDs, pixel array and amorphous silicon detectors, and online image plates.

Rivers, M. (UC)

2011-09-23

474

NASA Astrophysics Data System (ADS)

We define and investigate a quantization of null hypersurfaces in the context of loop quantum gravity on a fixed graph. The main tool we use is the parametrization of the theory in terms of twistors, which has already proved useful in discussing the interpretation of spin networks as the quantization of twisted geometries. The classical formalism can be extended in a natural way to null hypersurfaces, with the Euclidean polyhedra replaced by null polyhedra with spacelike faces, and SU(2) by the little group ISO(2). The main difference is that the simplicity constraints present in the formalism are all first class, and the symplectic reduction selects only the helicity subgroup of the little group. As a consequence, information on the shapes of the polyhedra is lost, and the result is a much simpler, Abelian geometric picture. It can be described by a Euclidean singular structure on the two-dimensional spacelike surface defined by a foliation of spacetime by null hypersurfaces. This geometric structure is naturally decomposed into a conformal metric and scale factors, forming locally conjugate pairs. Proper action-angle variables on the gauge-invariant phase space are described by the eigenvectors of the Laplacian of the dual graph. We also identify the variables of the phase space amenable to characterize the extrinsic geometry of the foliation. Finally, we quantize the phase space and its algebra using Dirac's algorithm, obtaining a notion of spin networks for null hypersurfaces. Such spin networks are labeled by SO(2) quantum numbers and are embedded nontrivially in the unitary, infinite-dimensional irreducible representations of the Lorentz group.

Speziale, Simone; Zhang, Mingyi

2014-04-01

475

We define and investigate a quantisation of null hypersurfaces in the context of loop quantum gravity on a fixed graph. The main tool we use is the parametrisation of the theory in terms of twistors, which has already proved useful in discussing the interpretation of spin networks as the quantization of twisted geometries. The classical formalism can be extended in a natural way to null hypersurfaces, with the Euclidean polyhedra replaced by null polyhedra with space-like faces, and SU(2) by the little group ISO(2). The main difference is that the simplicity constraints present in the formalims are all first class, and the symplectic reduction selects only the helicity subgroup of the little group. As a consequence, information on the shapes of the polyhedra is lost, and the result is a much simpler, abelian geometric picture. It can be described by an Euclidean singular structure on the 2-dimensional space-like surface defined by a foliation of space-time by null hypersurfaces. This geometric structure is naturally decomposed into a conformal metric and scale factors, forming locally conjugate pairs. Proper action-angle variables on the gauge-invariant phase space are described by the eigenvectors of the Laplacian of the dual graph. We also identify the variables of the phase space amenable to characterize the extrinsic geometry of the foliation. Finally, we quantise the phase space and its algebra using Dirac's algorithm, obtaining a notion of spin networks for null hypersurfaces. Such spin networks are labelled by SO(2) quantum numbers, and are embedded non-trivially in the unitary, infinite-dimensional irreducible representations of the Lorentz group.

Simone Speziale; Mingyi Zhang

2014-04-16