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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

3D Geometry Projection from 2D to 3D  

E-print Network

n n n zzz yyy xxx P Points = y x tsss tsss S 3,22,21,2 3,12,11,1 Some matrix = n n vvv uuu I 21 21 of the points in P. #12;5 First, look at 2D rotation (easier) - n n yyy xxx 21 21 ... cossin sincos coordinates. That is, it's rotated. #12;6 Simple 3D Rotation - n n n zzz yyy xxx 21 21 21 ... 100 0cossin 0

Jacobs, David

3

Higher order global differentiability local approximations for 2-D and 3-D distorted element geometries  

E-print Network

The primary focus of this thesis is to present a framework to develop higher order global differentiability local approximations for 2-D and 3-D distorted element geometries. The necessity and superiority of higher order global differentiability...

Maduri, Rajesh Kumar

2008-02-01

4

The 2D-to-3D geometry hopping in small boron clusters: The charge effect  

NASA Astrophysics Data System (ADS)

DFT TPSSh/6-311+G(d) calculations are carried out on a series of 2D and 3D forms of Bn, n = 20, 22 and 24 in different charge states. For a certain size, the relative energy within a pair of two-dimensional quasi-planar (2D) and three-dimensional staggered double-ring (3D) boron cluster isomers may shift the sign as they reach a certain charge state. Specifically, electron addition tends to enhance the stability of the 2D over the corresponding 3D isomer irrespective of the available electrons. Linear correlations between 2D-3D relative energy and net charge are established. Along with 2D-to-3D geometry hopping at critical size, our results suggest a local 2D-3D geometry hopping via critical charge.

Pham, Hung Tan; Duong, Long Van; Pham, Buu Quoc; Nguyen, Minh Tho

2013-07-01

5

A generalized 2D pencil beam scaling algorithm for proton dose calculation in heterogeneous slab geometries  

SciTech Connect

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

6

2-D Radiative Transfer in Protostellar Envelopes: I. Effects of Geometry on Class I Sources  

E-print Network

We present 2-D radiation transfer models of Class I Protostars and show the effect of including more realistic geometries on the resulting spectral energy distributions and images. We begin with a rotationally flattened infalling envelope as our comparison model, and add a flared disk and bipolar cavity. The disk affects the spectral energy distribution most strongly at edge-on inclinations, causing a broad dip at about 10 um (independent of the silicate feature) due to high extinction and low scattering albedo in this wavelength region. The bipolar cavities allow more direct stellar+disk radiation to emerge into polar directions, and more scattering radiation to emerge into all directions. The wavelength-integrated flux, often interpreted as luminosity, varies with viewing angle, with pole-on viewing angles seeing 2-4 times as much flux as edge-on, depending on geometry. Thus, observational estimates of luminosity should take into account the inclination of a source. The envelopes with cavities are significantly bluer in near-IR and mid-IR color-color plots than those without cavities. Using 1-D models to interpret Class I sources with bipolar cavities would lead to an underestimate of envelope mass and an overestimate of the implied evolutionary state. We compute images at near-, mid-, and far-IR wavelengths. We find that the mid-IR colors and images are sensitive to scattering albedo, and that the flared disk shadows the midplane on large size scales at all wavelengths plotted. Finally, our models produce polarization spectra which can be used to diagnose dust properties, such as albedo variations due to grain growth. Our results of polarization across the 3.1 um ice feature agree well with observations for ice mantles covering 5% of the radius of the grains.

Barbara A. Whitney; Kenneth Wood; J. E. Bjorkman; Michael J. Wolff

2003-03-21

7

Effects of Training Method and Gender on Learning 2D\\/3D Geometry  

Microsoft Academic Search

This article reports the findings of an experimental study involving 36 primary school students (16 girls, 20 boys, Mean age = 9.5 years, age range: 8-10 years) in geometrical understanding of 2D and 3D objects. Students were assigned into two experimental groups and one control group based on a stratified random sampling procedure. The first experimental group trained in an

Samsudin Khairulanuar; Abd Rashid Nazre; Omar Khan Sairabanu; Fabil Norasikin

2010-01-01

8

Determining Transition State Geometries in Liquids Using 2D-IR  

SciTech Connect

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

9

Refined structure of melittin bound to perdeuterated dodecylphosphocholine micelles as studied by 2D-NMR and distance geometry calculation  

Microsoft Academic Search

In our previous paper we reported the conformation of melittin bound to perdeuterated dodecylphosphocholine micelles as studied by ¹H NMR experiment and distance geometry calculation. No hydrogen bonds were taken into consideration explicitly in the calculation. However, mostly alpha-helical conformations were obtained as results of the calculation even with no explicitly assumed hydrogen bonds. In the present paper we refined

Teikichi Ikura; N. Go; Fuyuhiko Inagaki

1991-01-01

10

The influence of step geometry on the desorption characteristics of O2, D2, and H2O from stepped Pt surfaces  

NASA Astrophysics Data System (ADS)

We have compared the desorption characteristics of O2, D2, and H2O from the Pt(533) surface to the Pt(553) surface using temperature programmed desorption. Both surfaces consist of four atom wide (111) terraces interrupted by monoatomic steps of the different step geometries: (100) versus (110), respectively. We find that desorption is influenced significantly by the presence of step sites and the geometry of those sites. In general, molecules and atoms are thought to be bound more strongly to step sites than to terrace sites. Our D2 desorption data from Pt(553) provide an anomalous counterexample to this common belief since D atoms on this surface appear to be bound stronger by terrace sites. We also show that it is not possible to say a priori which step geometry will bind atoms or molecules stronger: recombinatively desorbing O atoms are bound stronger to (100) sites, whereas H2O molecules are bound stronger to (110) sites. Furthermore, the amount of adatoms or molecules that are affected by the presence of steps varies for the different species, as is evident from the various step: terrace ratios of ~1:1.3 for O2 (O), ~1:3 for D2 (D), and ~1:1 for H2O. This indicates that, in contrast to deuterium, more oxygen atoms and water molecules are affected by the presence of steps than would be expected on geometrical arguments alone.

van der Niet, Maria J. T. C.; den Dunnen, Angela; Juurlink, Ludo B. F.; Koper, Marc T. M.

2010-05-01

11

A Piecewise Linear Discontinuous Finite Element Spatial Discretization of the Transport Equation in 2D Cylindrical Geometry  

SciTech Connect

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

12

Effects of 3 dimensional crystal geometry and orientation on 1D and 2D time-scale determinations of magmatic processes using olivine and orthopyroxene  

NASA Astrophysics Data System (ADS)

One of the achievements in recent years in volcanology is the determination of time-scales of magmatic processes via diffusion in minerals and its addition to the petrologists' and volcanologists' toolbox. The method typically requires one-dimensional modeling of randomly cut crystals from two-dimensional thin sections. Here we address the question whether using 1D (traverse) or 2D (surface) datasets exploited from randomly cut 3D crystals introduces a bias or dispersion in the time-scales estimated, and how this error can be improved or eliminated. Computational simulations were performed using a concentration-dependent, finite-difference solution to the diffusion equation in 3D. The starting numerical models involved simple geometries (spheres, parallelepipeds), Mg/Fe zoning patterns (either normal or reverse), and isotropic diffusion coefficients. Subsequent models progressively incorporated more complexity, 3D olivines possessing representative polyhedral morphologies, diffusion anisotropy along the different crystallographic axes, and more intricate core-rim zoning patterns. Sections and profiles used to compare 1, 2 and 3D diffusion models were selected to be (1) parallel to the crystal axes, (2) randomly oriented but passing through the olivine center, or (3) randomly oriented and sectioned. Results show that time-scales estimated on randomly cut traverses (1D) or surfaces (2D) can be widely distributed around the actual durations of 3D diffusion (~0.2 to 10 times the true diffusion time). The magnitude over- or underestimations of duration are a complex combination of the geometry of the crystal, the zoning pattern, the orientation of the cuts with respect to the crystallographic axes, and the degree of diffusion anisotropy. Errors on estimated time-scales retrieved from such models may thus be significant. Drastic reductions in the uncertainty of calculated diffusion times can be obtained by following some simple guidelines during the course of data collection (i.e. selection of crystals and concentration profiles, acquisition of crystallographic orientation data), thus allowing derivation of robust time-scales.

Shea, Thomas; Krimer, Daniel; Costa, Fidel; Hammer, Julia

2014-05-01

13

Geometry  

NSDL National Science Digital Library

Geometry is the branch of mathematics which investigates the relations, properties, and measurement of solids, surfaces, lines, and angles. It is the science of the relations of space. Sourse: Webster's Dictionary

K-12 Outreach,

14

Quantitative simulation of ultrasonic time of flight diffraction technique in 2D geometries using Huygens-Fresnel diffraction model: theory and experimental comparison.  

PubMed

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

15

Geometry  

NSDL National Science Digital Library

Shapes, lines, and more! Here are some fun games to practice geometry and not get bored! Here\\'s a review to help you through the fun... Identify Geometric Shapes and then you will be on your way! After you have reviewed...show me all you know with this Shape Quiz and then all the fun begins!!! Is it a polygon or not? You tell me. Drag them into the bins and we will see! ...

Walker, Ms.

2008-03-31

16

Geometry  

NSDL National Science Digital Library

We are going to review and sharpen our geometry skills with these fun activities and websites! This game is similar to memory. Practice making making matches with this fun memory game. Match the shape to its definition! Think back to what we have learned and practice identifying geometric shapes and lines by the clues given. This game is timed! Re-arrange the colored pieces given to fit them into the square in ...

Jackson, Ms.

2008-03-24

17

Proton 2D NMR and distance geometry study of the folding of Ecballium elaterium trypsin inhibitor, a member of the squash inhibitors family  

Microsoft Academic Search

The solution conformation of synthetic Ecballium elaterium trypsin inhibitor II, a 28-residue peptide with 3 disulfide bridges, has been studied by ¹H 2D NMR measurements. Secondary structure elements were determined: a miniantiparallel β-sheet Met 7-Cys 9 and Gly 25-Cys 27, a β-hairpin 20-28 with β-turn 22-25, and two tight turns Asp 12-Cys 15 and Leu 16-Cys 19. A set of

Annie Heitz; Laurent Chiche; D. Le-Nguyen; Bertrand Castro

1989-01-01

18

Translating Basic Psychopathology Research to Preventive Interventions: A Tribute to John R. Z. Abela  

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

19

(+)-(R,Z)-5-Muscenone and (-)-(R)-muscone by enantioselective aldol reaction and Grob fragmentation.  

PubMed

(+)-(R,Z)-5-Muscenone ((R)-1) was synthesized by an enantioselective aldol reaction, catalyzed by new ephedrine-type Ti reagents (up to 70 % enantiomeric excess). Substrate-directed diastereoselective reduction of the aldol product and Grob fragmentation of the tosylate of the resultant 1,3-diol afforded (+)-1. This approach also gave access to (-)-(R,E)-5-muscenone and (-)-(R)-muscone. PMID:20077541

Fehr, Charles; Buzas, Andrea K; Knopff, Oliver; de Saint Laumer, Jean-Yves

2010-02-22

20

2D MHD calculations for recent Argon Double Shell Experiments on Double Eagle  

NASA Astrophysics Data System (ADS)

2D MHD calculations for Argon double puff z-pinch implosions in the 200ns, 4MA regime are compared with experimental results obtained on DOUBLE EAGLE at MPI. To do the calculations the 2D MHD code DELTA is employed. DELTA operates on a triangular unstructured mesh. To obtain the initial conditions for the implosion a module of DELTA, the NOZZLE code, is used to calculate the gas density distribution in r,z. The NOZZLE code solves the Navier-Stokes equations for the supersonic transient flow in the actual geometry from plenum to exit (see a companion paper by R. Ingermanson et al on this subject). DELTA is then used to follow the implosion dynamics of this initial density profile. A Collisional Radiation Equilibrium Model (CREMIT) is employed to calculate radiation self-consistently. The results of these calculations are compared with the experimentally measured K-shell radiation yield and power, as well as with filtered X-ray pinhole images designed to observe zippering and final pinch radius.

Waisman, Eduardo M.; Coleman, P.; Ingermanson, R.; Parks, D.; Steen, P.; Failor, B.; Levine, J.; Song, Y.; Sze, H.

1999-11-01

21

2d gauge theories and generalized geometry  

NASA Astrophysics Data System (ADS)

We show that in the context of two-dimensional sigma models minimal coupling of an ordinary rigid symmetry Lie algebra g leads naturally to the appearance of the "generalized tangent bundle" M? TM? T * M by means of composite fields. Gauge transformations of the composite fields follow the Courant bracket, closing upon the choice of a Dirac structure D ? M (or, more generally, the choide of a "small Dirac-Rinehart sheaf" ), in which the fields as well as the symmetry parameters are to take values. In these new variables, the gauge theory takes the form of a (non-topological) Dirac sigma model, which is applicable in a more general context and proves to be universal in two space-time dimensions: a gauging of g of a standard sigma model with Wess-Zumino term exists, iff there is a prolongation of the rigid symmetry to a Lie algebroid morphism from the action Lie algebroid M ? M into D ? M (or the algebraic analogue of the morphism in the case of ). The gauged sigma model results from a pullback by this morphism from the Dirac sigma model, which proves to be universal in two-spacetime dimensions in this sense.

Kotov, Alexei; Salnikov, Vladimir; Strobl, Thomas

2014-08-01

22

Translating basic psychopathology research to preventive interventions: a tribute to john R. Z. Abela.  

PubMed

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 response style), interpersonal (e.g., reassurance seeking, attachment, dependency), personality (e.g., neuroticism, self-criticism), and contextual (e.g., stress, parental depression). He introduced important methodological advances to the study of the hopelessness model of depression, especially in children, including the "weakest link" approach, cognitive priming, and idiographic measurement of stress. We briefly review what is currently known about the prevention of depression regarding intervention targets, content, outcomes, effect sizes, moderators, mediators, specificity, and durability. Next, we summarize several of Abela's contributions that are most relevant to the prevention of depression. We describe the implications of Abela's work for the development, implementation, and testing of programs aimed at preventing depression and discuss important challenges such as the transfer of training to and the personalization of interventions so as to capitalize on individuals' strengths versus compensate for their weaknesses. PMID:22891820

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

2012-01-01

23

2D r-z Analysis of Hohlraum Experiments on Sphinx Machine using Axial Radiation from a Wire Array Z-pinch  

Microsoft Academic Search

Axial radiation flux from an aluminum Z-pinch on SPHINX machine is used to drive 5 mm diameter, 7 mm height hohlraums. 2006 results demonstrated that >200 GW power in 10 ns could be achieved creating >35 eV radiation temperatures. A 20-30 ns delay between the axial power starting time and the temperature rise had, however, to be explained. In this

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

2007-01-01

24

Implementation of a hybrid particle code with a PIC description in r-z and a gridless description in $\\phi$ into OSIRIS  

E-print Network

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 [A. Lifschitz et al., J. Comp. Phys. 228 (5) (2009) 1803-1814] to model one such problem, laser wakefield acceleration, by expanding the fields and currents in azimuthal harmonics and truncating the expansion after only the first harmonic. 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 co...

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

2014-01-01

25

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.; Ramrez, J.

2009-06-01

26

Diffusion Geometry Diffusion Geometry  

E-print Network

Diffusion Geometry Diffusion Geometry for High Dimensional Data Matthew J. Hirn July 3, 2013 #12;Diffusion Geometry Introduction Embedding of closed curve Figure: Left: A closed, non-self-intersecting curve in 3 dimensions. Right: Its embedding as a circle. #12;Diffusion Geometry Introduction Cartoon

Hirn, Matthew

27

Model capabilities, 2-D  

NASA Technical Reports Server (NTRS)

Two dimensional (2-D) atmospheric models provide results for altitude versus latitude as a function of time and are developed primarily for two reasons: to help understand atmospheric occurrences and to give assessments and/or make predictions of future changes in the atmosphere. Historically, the formulation of transport in 2-D models has been a difficult problem. Most current 2-D models have a transport that is either an Eulerian mean circulation with large stratospheric eddy diffusion or a residual (diabatic or Lagragian) mean circulation which typically is accompanied with small stratospheric eddy diffusion. Because of the assumption of zonal averaging, 2-D models are primarily useful in making predictions of atmospheric changes of time scales longer than a season. Although decadel atmospheric changes may be reasonably well represented with a 2-D model, the year to year changes which result from interannual transport differences, stratospheric warmings, semiannual oscillations, or quasi-biennial oscillations may not be well represented in the stratosphere and troposphere.

Jackman, Charles H.

1992-01-01

28

A transient, quadratic nodal method for triangular-Z geometry  

SciTech Connect

Many systematically-derived nodal methods have been developed for Cartesian geometry due to the extensive interest in Light Water Reactors. These methods typically model the transverse-integrated flux as either an analytic or low order polynomial function of position within the node. Recently, quadratic nodal methods have been developed for R-Z and hexagonal geometry. A static and transient quadratic nodal method is developed for triangular-Z geometry. This development is particularly challenging because the quadratic expansion in each node must be performed between the node faces and the triangular points. As a consequence, in the 2-D plane, the flux and current at the points of the triangles must be treated. Quadratic nodal equations are solved using a non-linear iteration scheme, which utilizes the corrected, mesh-centered finite difference equations, and forces these equations to match the quadratic equations by computing discontinuity factors during the solution. Transient nodal equations are solved using the improved quasi-static method, which has been shown to be a very efficient solution method for transient problems. Several static problems are used to compare the quadratic nodal method to the Coarse Mesh Finite Difference (CMFD) method. The quadratic method is shown to give more accurate node-averaged fluxes. However, it appears that the method has difficulty predicting node leakages near reactor boundaries and severe material interfaces. The consequence is that the eigenvalue may be poorly predicted for certain reactor configurations. The transient methods are tested using a simple analytic test problem, a heterogeneous heavy water reactor benchmark problem, and three thermal hydraulic test problems. Results indicate that the transient methods have been implemented correctly.

DeLorey, T.F.

1993-06-01

29

2D visual servoing  

Microsoft Academic Search

We propose an approach to vision-based robot control, called 2D visual servoing, which avoids the respective drawbacks of classical position-based and image-based visual servoing. Contrary to the position-based visual servoing, our scheme does not need any geometric three-dimensional model of the object. Furthermore and contrary to image-based visual servoing, our approach ensures the convergence of the control law in the

Ezio Malis; F. Chaumette; S. Boudet

1999-01-01

30

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

SciTech Connect

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

31

Astronomical Parallax 2D  

NSDL National Science Digital Library

The Astronomical Parallax 2D Model illustrates the phenomenon of parallax in astronomy. Parallax is the apparent displacement of an object relative to the background that is caused by the motion of the observer (rather than the motion of the object itself, or of the background). This simulation illustrates the parallax of an object in space that results from the Earth's rotational or orbital motions. The simulation has two different modes. The default is an Earth Rotation Mode. In this mode the simulation illustrates the parallax caused by Earth's rotation on its axis. The top window shows an observer (indicated by a green dot) on the equator of Earth (blue disk). The green line shows that observer's line of sight to an object in space (indicated by a red dot). This line of sight extends to show where the object would appear against a more distant background. When the simulation is played the observer moves around the Earth as Earth rotates. Parallax causes the apparent position of the object to move back and forth between two extreme locations (indicated by open red circles). The bottom window shows the apparent motion of the object against the stars, as seen by the observer. [Note: to keep the simulation simple it is assumed that Earth's equator is aligned with the ecliptic plane (the plane of Earth's orbit). In actual fact they are tilted by 23.5 degrees, but this cannot be represented in a simple 2D simulation.] The other mode for the simulation is Earth Orbit Mode. In this mode the simulation illustrates the parallax caused by Earth's orbit around the Sun. Now the observer moves along Earth's orbital path (shown as a blue circle with the orange Sun in the center). The bottom window now shows the apparent motion of the Sun as well as that of the object being observed.

Timberlake, Todd

2011-05-18

32

Lectures on 2D gravity and 2D string theory  

Microsoft Academic Search

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

33

2D Mapping and LIF Tomography of an Expanding Magnetoplasma  

NASA Astrophysics Data System (ADS)

Previous experiments showed that adiabatic expansion of plasma provides high uniformity of ejected flux and up to 100 eV of ion energy from the electric field generated by the density gradient. Such plasmas are suitable for applications as plasma-based thrusters for spacecraft propulsion as well as energetic ion sources in plasma surface processing. We report on experiments performed in the expansion region between a steady state, high density, helicon plasma source and a large diffusion chamber (1.8 m diameter, 4.4 m length) in which the ion ? is below 10-2 but greater than m_e/m_i. 2D mapping has been accomplished by measuring the magnetic fluctuation spectrum, electron temperature, electron density, and plasma potential at different locations in the horizontal (r,z) plane. Furthermore, by using the rotation capability of our scanning probe we are able to obtain the entire 2D ion distribution function through tomographic inversion of chordal measurements. The ion flow results are consistent with the spontaneous formation of an electric double layer at the end of the helicon source.

Biloiu, C.; Compton, C.; Hardin, R.; Keesee, A.; McGeehan, B.; Scime, E.; Sun, X.

2003-10-01

34

2D photonic-crystal optomechanical nanoresonator  

E-print Network

We present the optical optimization of an optomechanical device based on a suspended InP membrane patterned with a 2D near-wavelength grating (NWG) based on a 2D photonic-crystal geometry. We first identify by numerical simulation a set of geometrical parameters providing a reflectivity higher than 99.8 % over a 50-nm span. We then study the limitations induced by the finite value of the optical waist and lateral size of the NWG pattern using different numerical approaches. The NWG grating, pierced in a suspended InP 265 nm-thick membrane, is used to form a compact microcavity involving the suspended nano-membrane as end mirror. The resulting cavity has a waist size smaller than 10 $\\mu$m and a finesse in the 200 range. It is used to probe the Brownian motion of the mechanical modes of the nanomembrane.

K. Makles; T. Antoni; A. G. Kuhn; S. Delglise; T. Briant; P. F. Cohadon; R. Braive; G. Beaudoin; L. Pinard; C. Michel; V. Dolique; R. Flaminio; G. Cagnoli; I. Robert-Philip; A. Heidmann

2014-10-23

35

2D photonic-crystal optomechanical nanoresonator  

E-print Network

We present the optical optimization of an optomechanical device based on a suspended InP membrane patterned with a 2D near-wavelength grating (NWG) based on a 2D photonic-crystal geometry. We first identify by numerical simulation a set of geometrical parameters providing a reflectivity higher than 99.8 % over a 50-nm span. We then study the limitations induced by the finite value of the optical waist and lateral size of the NWG pattern using different numerical approaches. The NWG grating, pierced in a suspended InP 265 nm-thick membrane, is used to form a compact microcavity involving the suspended nano-membrane as end mirror. The resulting cavity has a waist size smaller than 10 $\\mu$m and a finesse in the 200 range. It is used to probe the Brownian motion of the mechanical modes of the nanomembrane.

Makles, K; Kuhn, A G; Delglise, S; Briant, T; Cohadon, P F; Braive, R; Beaudoin, G; Pinard, L; Michel, C; Dolique, V; Flaminio, R; Cagnoli, G; Robert-Philip, I; Heidmann, A

2014-01-01

36

Lie symmetries and 2D Material Physics  

E-print Network

Inspired from Lie symmetry classification, we establish a correspondence between rank two Lie symmetries and 2D material physics. The material unit cell is accordingly interpreted as the geometry of a root system. The hexagonal cells, appearing in graphene like models, are analyzed in some details and are found to be associated with A_2 and G_2 Lie symmetries. This approach can be applied to Lie supersymmetries associated with fermionic degrees of freedom. It has been suggested that these extended symmetries can offer a new way to deal with doping material geometries. Motivated by Lie symmetry applications in high energy physics, we speculate on a possible connection with (p,q) brane networks used in the string theory compactification on singular Calabi-Yau manifolds.

Adil Belhaj; Moulay Brahim Sedra

2014-04-18

37

2-D pointing while walking  

Microsoft Academic Search

A frequent assertion in wearable computer discussions is that WIMP (windows\\/icons\\/mouse\\/pointer) interfaces are inappropriate for wearable computers, in part because 2-D (two-dimensional) pointing is difficult while walking. This paper summarizes findings from user studies conducted by Tangis Corporation on the usability of pointing devices for wearable computers. The author finds that, with changes, 2-D pointing could be an adequate interim

Lisa Louise Davis

2001-01-01

38

2D and 3D Numerical Models of Inductive SFCL  

Microsoft Academic Search

The Superconducting Fault Current Limiter (SFCL) can be used to limit the short-circuit current level in electrical networks. The inductive SFCL works like a transformer with shorted secondary HTS winding. Because of the iron core, the inductive SFCL is not axially symmetrical and should be modeled in 3D geometry. On the other hand, the 2D modeling gives much more computational

S. Kozak; T. Janowski; G. Wojtasiewicz

2007-01-01

39

2-D Finite Element Cable and Box IEMP Analysis  

SciTech Connect

A 2-D finite element code has been developed for the solution of arbitrary geometry cable SGEMP and box IEMP problems. The quasi- static electric field equations with radiation- induced charge deposition and radiation-induced conductivity y are numerically solved on a triangular mesh. Multiple regions of different dielectric materials and multiple conductors are permitted.

Scivner, G.J.; Turner, C.D.

1998-12-17

40

TOPAZ2D. 2D FEM Heat Transfer & E&M Field Code  

SciTech Connect

TOPAZ and TOPAZ2D are two-dimensional implicit finite element computer codes for heat transfer analysis. TOPAZ2D can also be used to solve electrostatic and magnetostatic problems. The programs solve for the steady-state or transient temperature or electrostatic and magnetostatic potential field on two-dimensional planar or axisymmetric geometries. Material properties may be temperature or potential-dependent and either isotropic or orthotropic. A variety of time and temperature-dependent boundary conditions can be specified including temperature, flux, convection, and radiation. By implementing the user subroutine feature, users can model chemical reaction kinetics and allow for any type of functional representation of boundary conditions and internal heat generation. The programs can solve problems of diffuse and specular band radiation in an enclosure coupled with conduction in the material surrounding the enclosure. Additional features include thermal contact resistance across an interface, bulk fluids, phase change, and energy balances.

Shapiro, A.B. [Lawrence Livermore National Lab., CA (United States)

1987-04-01

41

STP Ising 2D Program  

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

42

All c2d Spitzer Outflows  

NASA Astrophysics Data System (ADS)

Protostellar outflows can be well identified as diffuse knots in Spitzer IRAC images. We therefore propose to systematically search and characterize all outflows covered by the most extensive Spitzer imaging survey of local star formation, the Cores to Disks (c2d) Spitzer Legacy Program. This would create an extensive, homogenously studied (publicly available) legacy-style outflow sample without biases, likely the most comprehensive one available to date. It would replace existing studies that usually employ different methods for different regions, and do never probe a volume of the scale covered by c2d (5 large cloud complexes and about 90 isolated dense molecular cores). Our homogenous approach would, e.g., also allow to see known outflows in a new light, since existing analysis (e.g., on the geometry) is hard to compare between different samples. Furthermore, also young stellar objects can be well identified and characterized using Spitzer IRAC and MIPS images. This allows to probe the sources driving outflows, again in a more homogenous fashion than possible for previous studies. Based on existing complementary c2d data, which covers the 1 to 1000 micron wavelength range, we would derive protostellar properties (like bolometric luminosity and temperature) and associate these with the outflow properties. Thus, Spitzer?s unparalleled sensitivity to both outflows and stars offers the unique chance to systematically relate the properties of outflows to the ones of the driving sources without biases. No grande-scale study of this type has been conducted so far, in particular none relying on a single, homogenous dataset covering a significant fraction of the local star formation. Our survey would, e.g., be critical in gauging the relative abundance of parsec-scale, ?S-shaped?, and quadrupolar outflows. This is important, given that such flows provide significant energy transfer over large (cloud-size) scales, possibly indicate jet precession, and may hint at protostellar binaries, respectively.

Goodman, Alyssa; Allen, Lori; Arce, Hector; Borkin, Michelle; Bourke, Tyler; Evans, Neal; Foster, Jonathan; Huard, Tracy; Kauffmann, Jens; Pineda, Jaime; Stapelfeldt, Karl

2007-05-01

43

The 2D ?-Dirac oscillator  

NASA Astrophysics Data System (ADS)

In this Letter, 2D Dirac oscillator in the quantum deformed framework generated by the ?-Poincar-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

44

Subtracted geometry from Harrison transformations  

NASA Astrophysics Data System (ADS)

We consider the rotating non-extremal black hole of N=2 D=4 STU supergravity carrying three magnetic charges and one electric charge. We show that its subtracted geometry is obtained by applying a specific SO(4,4) Harrison transformation on the black hole. As previously noted, the resulting subtracted geometry is a solution of the N=2 S=T=U supergravity.

Virmani, Amitabh

2012-07-01

45

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

SciTech Connect

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

46

Plateau border bulimia transition: discontinuities expected in three simple experiments on 2D liquid foams  

Microsoft Academic Search

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

Pierre Rognon; Franois Molino; Cyprien Gay

2009-01-01

47

2D-to-3D Photo Rendering for 3D Displays Dario Comanducci  

E-print Network

fast and effective ap- proach to 2D-3D conversion of an image pair for the three- dimensional rendering2D-to-3D Photo Rendering for 3D Displays Dario Comanducci Dip. di Sistemi e Informatica, Univ. di geometry, and an original algorithm for the recovery of 3D visual param- eters from the properties

Martin, Ralph R.

48

Cooling power enhancement for 2-D and 3-D CPC sky radiators  

Microsoft Academic Search

This work describes the experimental results of the newly proposed 2-D and 3-D sky radiators. In order to enhance the performance of sky radiation cooling, the authors have proposed a compound parabolic concentrating (CPC) sky radiator with 2-D geometry and demonstrated that the CPC sky radiator has a greater cooling performance than the conventional flat plate one. In the present

Takeo S. SAITOH; Jun TAKAHASHI

2002-01-01

49

Multi-Chart Geometry Images  

Microsoft Academic Search

We introduce multi-chart geometry images, a new representation for arbitrary surfaces. It is created by resampling a surface onto a regular 2D grid. Whereas the original scheme of Gu et al. maps the entire surface onto a single square, we use an atlas construction to map the surface piecewise onto charts of arbitrary shape. We demonstrate that this added flexibility

Pedro V. Sander; Zo J. Wood; Steven J. Gortler; John Snyder; Hugues Hoppe

2003-01-01

50

Projective Geometry  

NSDL National Science Digital Library

This site departs from the common themes taught in general geometry classes and introduces projective geometry, which has to do with special properties resulting from the intersection of lines, planes, and points. The coincidence of such elements is what is referred to as an incidence, and this is the basis of the topic. The site makes extensive use of animated figures to demonstrate principles involved in projective geometry, such as path curves, pivot transforms, and the curious concept of counter space. The author does a good job of explaining what is depicted in the figures as well as the underlying theory.

51

Geometry Sender  

NSDL National Science Digital Library

The Geometry Sender at Keio University includes many 3D object data, including WebOOGL, off, rwx format, tutorial on data formats, and information about external viewers for 3D object on Web are available.

52

2D quasiperiodic plasmonic crystals  

PubMed Central

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

53

2D quasiperiodic plasmonic crystals.  

PubMed

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

54

2D quasiperiodic plasmonic crystals  

NASA Astrophysics Data System (ADS)

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.

Bauer, Christina; Kobiela, Georg; Giessen, Harald

2012-12-01

55

Ultrafast 2D IR Vibrational Echo Spectroscopy  

E-print Network

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 systems. The form and time evolution of the 2D IR spectrum permits examination of processes that cannot

Fayer, Michael D.

56

Algebraic Geometry  

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

57

Velocimetry Analysis of 2D Turbulence Imaging Data from Beam Emission Spectroscopy  

NASA Astrophysics Data System (ADS)

The time-resolved velocity field of density fluctuations contains pertinent dynamics on critical features of plasma turbulence, including zonal flow and geodesic acoustic mode behavior, and the ExB motion from underlying electrostatic potential fluctuations. This velocity field may be used to infer the Reynolds stress (d/dr), thought to drive zonal flows, and the radial turbulent particle flux. The beam emission spectroscopy (BES) system on DIII-D obtains radially and poloidally resolved images (up to 8x8) of density fluctuations at 1 cm resolution. The orthogonal dynamic programming method, developed in fluid dynamics, is used to extract the 2D flow field, v(r,z,t) from the fluctuating densities. A vector-matching method determines structure motion from one frame to another. The technique will also be applied to density data from nonlinear GYRO simulations of turbulence, using an appropriate BES synthetic diagnostic. The inferred 2D density fluctuation velocity field will be compared with the ExB fluctuations also calculated from GYRO to discern their relationship and wavenumber sensitivity.

McKee, G. R.; Fonck, R. J.; Yan, Z.; Holland, C.

2012-10-01

58

MAGNUM2D. Radionuclide Transport Porous Media  

SciTech Connect

MAGNUM2D was developed to analyze thermally driven fluid motion in the deep basalts below the Paco Basin at the Westinghouse Hanford Site. Has been used in the Basalt Waste Isolation Project to simulate nonisothermal groundwater flow in a heterogeneous anisotropic medium and heat transport in a water/rock system near a high level nuclear waste repository. Allows three representations of the hydrogeologic system: an equivalent porous continuum, a system of discrete, unfilled, and interconnecting fractures separated by impervious rock mass, and a low permeability porous continuum with several discrete, unfilled fractures traversing the medium. The calculations assume local thermodynamic equilibrium between the rock and groundwater, nonisothermal Darcian flow in the continuum portions of the rock, and nonisothermal Poiseuille flow in discrete unfilled fractures. In addition, the code accounts for thermal loading within the elements, zero normal gradient and fixed boundary conditions for both temperature and hydraulic head, and simulation of the temperature and flow independently. The Q2DGEOM preprocessor was developed to generate, modify, plot and verify quadratic two dimensional finite element geometries. The BCGEN preprocessor generates the boundary conditions for head and temperature and ICGEN generates the initial conditions. The GRIDDER postprocessor interpolates nonregularly spaced nodal flow and temperature data onto a regular rectangular grid. CONTOUR plots and labels contour lines for a function of two variables and PARAM plots cross sections and time histories for a function of time and one or two spatial variables. NPRINT generates data tables that display the data along horizontal or vertical cross sections. VELPLT differentiates the hydraulic head and buoyancy data and plots the velocity vectors. The PATH postprocessor plots flow paths and computes the corresponding travel times.

Langford, D.W. [Boeing Computer Services, Richland, WA (United States); Baca, R.G. [EG and G Idaho Inc., Idaho Falls, ID (United States)

1989-03-01

59

MAGNUM2D. Radionuclide Transport Porous Media  

SciTech Connect

MAGNUM2D was developed to analyze thermally driven fluid motion in the deep basalts below the Paco Basin at the Westinghouse Hanford Site. Has been used in the Basalt Waste Isolation Project to simulate nonisothermal groundwater flow in a heterogeneous anisotropic medium and heat transport in a water/rock system near a high level nuclear waste repository. Allows three representations of the hydrogeologic system: an equivalent porous continuum, a system of discrete, unfilled, and interconnecting fractures separated by impervious rock mass, and a low permeability porous continuum with several discrete, unfilled fractures traversing the medium. The calculation assumes local thermodynamic equilibrium between the rock and groundwater, nonisothermal Darcian flow in the continuum portions of the rock, and nonisothermal Poiseuille flow in discrete unfilled fractures. In addition, the code accounts for thermal loading within the elements, zero normal gradient and fixed boundary conditions for both temperature and hydraulic head, and simulation of the temperature and flow independently. The Q2DGEOM preprocessor was developed to generate, modify, plot and verify quadratic two dimensional finite element geometries. The BCGEN preprocessor generates the boundary conditions for head and temperature and ICGEN generates the initial conditions. The GRIDDER postprocessor interpolates nonregularly spaced nodal flow and temperature data onto a regular rectangular grid. CONTOUR plots and labels contour lines for a function of two variables and PARAM plots cross sections and time histories for a function of time and one or two spatial variables. NPRINT generates data tables that display the data along horizontal or vertical cross sections. VELPLT differentiates the hydraulic head and buoyancy data and plots the velocity vectors. The PATH postprocessor plots flow paths and computes the corresponding travel times.

Langford, D.W. [Boeing Computer Services, Richland, WA (United States); Baca, R.G. [EG and G Idaho Inc., Idaho Falls, ID (United States)

1988-08-01

60

TOPAZ. 2D Finite Element Heat Conduction Code  

SciTech Connect

TOPAZ and TOPAZ2D are two-dimensional implicit finite element computer codes for heat transfer analysis. TOPAZ2D can also be used to solve electrostatic and magnetostatic problems. The programs solve for the steady-state or transient temperature or electrostatic and magnetostatic potential field on two-dimensional planar or axisymmetric geometries. Material properties may be temperature or potential-dependent and either isotropic or orthotropic. A variety of time and temperature-dependent boundary conditions can be specified including temperature, flux, convection, and radiation. By implementing the user subroutine feature, users can model chemical reaction kinetics and allow for any type of functional representation of boundary conditions and internal heat generation. The programs can solve problems of diffuse and specular band radiation in an enclosure coupled with conduction in the material surrounding the enclosure. Additional features include thermal contact resistance across an interface, bulk fluids, phase change, and energy balances.

Shapiro, A.B. [Lawrence Livermore National Lab., CA (United States)

1985-01-01

61

A continuous phase-modulated approach to spatial encoding in ultrafast 2D NMR spectroscopy  

Microsoft Academic Search

Ultrafast 2D NMR replaces the time-domain parametrization usually employed to monitor the indirect-domain spin evolution, with an equivalent encoding along a spatial geometry. When coupled to a gradient-assisted decoding during the acquisition, this enables the collection of complete 2D spectra within a single transient. We have presented elsewhere two strategies for carrying out the spatial encoding underlying ultrafast NMR: a

Assaf Tal; Boaz Shapira; Lucio Frydman

2005-01-01

62

Staring 2-D hadamard transform spectral imager  

DOEpatents

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

63

Spinor geometry  

E-print Network

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

64

Spinor geometry  

E-print Network

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.

Nicolaidis, A

2012-01-01

65

2D foam coarsening in a microfluidic system  

NASA Astrophysics Data System (ADS)

We report an experimental study of 2D microfoam coarsening confined in a micrometer scale geometry, the typical bubbles diameter being of the order of 50-100 ?m. These experiments raise both fundamental and applicative issues. For applicative issues: what is the typical time of foam ageing (for a polydisperse foam) in microsystems in scope of gas pocket storage in lab-on-a-chips? Experimental results show that a typical time of 2-3 mn is found, leading to the possibility of short-time storing, depending on the application. For fundamental interests, 2D foam ageing is generally described by von Neumann's law (von Neumann J., Metal Interfaces (American Society of Metals, Cleveland) 1952, p. 108) which is based on the hypothesis that bubbles are separated by thin films. Does this hypothesis still hold for foams confined in a 40 ?m height geometry? This problematic is analyzed and it is shown that von Neumann's law still holds but that the diffusion coefficient involved in this law is modified by the confinement which imposes a curvature radius at Plateau borders. More precisely, it is shown that the liquid fraction is high on a film cross-section, in contrast with macrometric experiments where drainage occurs. An analytical description of the diffusion is developped taking into account the fact that soap film height is only a fraction of the cell height. While most of microfoams are flowing, the experimental set-up we describe leads to the achievement of a motionless confined microfoam.

Marchalot, J.; Lambert, J.; Cantat, I.; Tabeling, P.; Jullien, M.-C.

2008-09-01

66

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

67

Conformation of self-assembled porphyrin dimers in liposome vesicles by phase-modulation 2D fluorescence spectroscopy  

E-print Network

By applying a phase-modulation fluorescence approach to 2D electronic spectroscopy, we studied the conformation-dependent exciton-coupling of a porphyrin dimer embedded in a phospholipid bilayer membrane. Our measurements specify the relative angle and separation between interacting electronic transition dipole moments, and thus provide a detailed characterization of dimer conformation. Phase-modulation 2D fluorescence spectroscopy (PM-2D FS) produces 2D spectra with distinct optical features, similar to those obtained using 2D photon-echo spectroscopy (2D PE). Specifically, we studied magnesium meso tetraphenylporphyrin dimers, which form in the amphiphilic regions of 1,2-distearoyl-sn-glycero-3-phosphocholine liposomes. Comparison between experimental and simulated spectra show that while a wide range of dimer conformations can be inferred by either the linear absorption spectrum or the 2D spectrum alone, consideration of both types of spectra constrains the possible structures to a "T-shaped" geometry. The...

Lott, Geoffrey A; Utterback, James K; Widom, Julia R; Aspuru-Guzik, Aln; Marcus, Andrew H

2011-01-01

68

Enrichment Activities for Geometry.  

ERIC Educational Resources Information Center

Enrichment activities that teach about geometry as they instruct in geometry are given for some significant topics. The facets of geometry included are tessellations, round robin tournaments, geometric theorems on triangles, and connections between geometry and complex numbers. (MNS)

Usiskin, Zalman

1983-01-01

69

Brittle damage models in DYNA2D  

SciTech Connect

DYNA2D is an explicit Lagrangian finite element code used to model dynamic events where stress wave interactions influence the overall response of the system. DYNA2D is often used to model penetration problems involving ductile-to-ductile impacts; however, with the advent of the use of ceramics in the armor-anti-armor community and the need to model damage to laser optics components, good brittle damage models are now needed in DYNA2D. This report will detail the implementation of four brittle damage models in DYNA2D, three scalar damage models and one tensor damage model. These new brittle damage models are then used to predict experimental results from three distinctly different glass damage problems.

Faux, D.R.

1997-09-01

70

A Search for Interstellar CH2D+  

Microsoft Academic Search

We report on a search for interstellar CH2D+. Four transitions occur in easily accessible portions of the spectrum; we report on emission at the frequencies of these transitions toward high column density star-forming regions. While the observations can be interpreted as being consistent with a detection of the molecule, further observations will be needed to secure its identification. The CH2D+

Alwyn Wootten; Barry E. Turner

2008-01-01

71

Minimizing user intervention in registering 2D images to 3D models  

Microsoft Academic Search

This paper proposes a novel technique to speed up the registration of 2D images to 3D models. This problem often arises in the process of digitalization of real objects, because pictures are often taken independently from the 3D geometry. Although there are a number of methods to solve the prob- lem of registration automatically, they all need some further assumptions,

Thomas Franken; Matteo Dellepiane; Fabio Ganovelli; Paolo Cignoni; Claudio Montani; Roberto Scopigno

2005-01-01

72

Effect of microstructural topology upon the stiffness and strength of 2D cellular structures  

Microsoft Academic Search

This paper explores the relation between the microstructure and the effective properties of cellular solids. Most available models are based on Voronoi structures, giving a limitation in the cell geometry diversity. In this study, circular cylinder packings followed by radical plane determination leads to various 2D structures exhibiting bimodal or multimodal cell size distributions. These structures are then modelled by

A Fazekas; R Dendievel; L Salvo; Y Brchet

2002-01-01

73

The Use of Geometric Properties of 2D Arrays across Development  

ERIC Educational Resources Information Center

Four- to 10-year-old children (n = 50) participated in a 2D search task that included geometry (with- and without lines) and feature conditions. During each of 27 trials, participants watched as a cartoon character hid behind one of three landmarks arranged in a triangle on a computer screen. During feature condition trials, participants could use

Gibson, Brett M.; Leichtman, Michelle D.; Costa, Rachel; Bemis, Rhyannon

2009-01-01

74

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

75

Rat CYP2D2, not 2D1, is functionally conserved with human CYP2D6 in endogenous morphine formation  

PubMed Central

The assumption that CYP2D1 is the corresponding rat cytochrome to human CYP2D6 has been revisited using recombinant proteins in direct enzyme assays. CYP2D1 and 2D2 were incubated with known CYP2D6 substrates, the three morphine precursors thebaine, codeine and (R)-reticuline. Mass spectrometric analysis showed that rat CYP2D2, not 2D1, catalyzed the 3-O-demethylation reaction of thebaine and codeine. In addition, CYP2D2 incubated with (R)-reticuline generated four products corytuberine, pallidine, salutaridine and isoboldine while rat CYP2D1 was completely inactive. This intramolecular phenol-coupling reaction follows the same mechanism as observed for CYP2D6. Michaelis-Menten kinetic parameters revealed high catalytic efficiencies for rat CYP2D2. These findings suggest a critical evaluation of other commonly accepted, however untested, CYP2D1 substrates. PMID:22641033

Grobe, Nadja; Kutchan, Toni M.; Zenk, Meinhart H.

2012-01-01

76

2D microwave imaging reflectometer electronicsa)  

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

77

Novel antenna coupled 2D plasmonic terahertz detection.  

SciTech Connect

Resonant plasmonic detectors are potentially important for terahertz (THz) spectroscopic imaging. We have fabricated and characterized antenna coupled detectors that integrate a broad-band antenna, which improves coupling of THz radiation. The vertex of the antenna contains the tuning gates and the bolometric barrier gate. Incident THz radiation may excite 2D plasmons with wave-vectors defined by either a periodic grating gate or a plasmonic cavity determined by ohmic contacts and gate terminals. The latter approach of exciting plasmons in a cavity defined by a short micron-scale channel appears most promising. With this short-channel geometry, we have observed multiple harmonics of THz plasmons. At 20 K with detector bias optimized we report responsivity on resonance of 2.5 kV/W and an NEP of 5 x 10{sup -10} W/Hz{sup 1/2}.

Allen, Jim (UC Santa Barbara); Dyer, Greg (UC Santa Barbara); Reno, John Louis; Shaner, Eric Arthur

2010-03-01

78

Inkjet Printing of 2D Layered Materials.  

PubMed

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; Ostling, Mikael

2014-11-10

79

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

80

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

81

TOPAZ2D heat transfer code users manual and thermal property data base  

SciTech Connect

TOPAZ2D is a two dimensional implicit finite element computer code for heat transfer analysis. This user's manual provides information on the structure of a TOPAZ2D input file. Also included is a material thermal property data base. This manual is supplemented with The TOPAZ2D Theoretical Manual and the TOPAZ2D Verification Manual. TOPAZ2D has been implemented on the CRAY, SUN, and VAX computers. TOPAZ2D can be used to solve for the steady state or transient temperature field on two dimensional planar or axisymmetric geometries. Material properties may be temperature dependent and either isotropic or orthotropic. A variety of time and temperature dependent boundary conditions can be specified including temperature, flux, convection, and radiation. Time or temperature dependent internal heat generation can be defined locally be element or globally by material. TOPAZ2D can solve problems of diffuse and specular band radiation in an enclosure coupled with conduction in material surrounding the enclosure. Additional features include thermally controlled reactive chemical mixtures, thermal contact resistance across an interface, bulk fluid flow, phase change, and energy balances. Thermal stresses can be calculated using the solid mechanics code NIKE2D which reads the temperature state data calculated by TOPAZ2D. A three dimensional version of the code, TOPAZ3D is available. The material thermal property data base, Chapter 4, included in this manual was originally published in 1969 by Art Edwards for use with his TRUMP finite difference heat transfer code. The format of the data has been altered to be compatible with TOPAZ2D. Bob Bailey is responsible for adding the high explosive thermal property data.

Shapiro, A.B.; Edwards, A.L.

1990-05-01

82

Modelling RF sources using 2-D PIC codes  

SciTech Connect

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

83

Modelling RF sources using 2-D PIC codes  

SciTech Connect

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

84

2D Mesoscale Simulations of Projectile Penetration into Sand  

NASA Astrophysics Data System (ADS)

Physical Phenomena governing projectile instabilities during penetration of granular media (e.g. sand) are not well understood. To gain insight into projectile -- granular media interactions, 2-D mesoscale simulations were performed to examine projectile penetration into sand targets with explicit representation of sand grains and representative porosities. The computational procedure used to generate a mesoscale representation of a sand target is presented with emphasis on an energy minimization technique for grain placement and modified Voronoi tessellations to enforce desired grain size and geometry. Simulated sand targets are shown to reproduce grain size distributions and porosities as large as 30% in close agreement with input parameters. Further, initial results from 2D mesoscale simulations, using the ISP-TROTP code, of normal impact of ogive shaped impactors at 0.5 km/s, 1.0 km/s, and 1.5 km/s impact velocities show that heterogeneous deformation in a frictionless granular media can cause deviation of projectile motion from normal direction indicating projectile instability during penetration. Efforts to achieve an improved description of granular media are underway. Work supported by DOE and AFOSR.

Teeter, R. D.; Dwivedi, S. K.; Felice, C. W.; Gupta, Y. M.

2007-06-01

85

Elucidation of 2D and 3D photoacoustic tomography  

NASA Astrophysics Data System (ADS)

Photoacoustic tomography (PAT), also known as thermoacoustic or optoacoustic tomography, is a hybrid imaging modality that reconstructs the electromagnetic absorption properties of biological tissue from knowledge of acoustic signals produced by the thermoacoustic effect. Because the propagation of acoustic signals is most generally described by the 3D wave equation, PAT is an inherently 3D imaging modality. Due to the the limited penetration depth of the probing electromagnetic fields and the limited availability of 3D ultrasound detector arrays, a simplified two-dimensional (2D) PAT measurement geometry is used in many current experimental implementations. However, in this case, when unfocused transducers are employed, the acquired data are not sufficient to invert the 3D imaging model and ad hoc reconstruction procedures are employed. In this work we numerically investigate 2D and 3D PAT assuming an ultrasound transducer having an anisotropic detection response. The uncompensated effects of an anisotropic detection response on images reconstructed using a point-detector assumption are demonstrated.

Wang, Kun; Zhang, Jin; Anastasio, Mark A.

2008-02-01

86

2-d Microcavities: Theory and Experiments  

E-print Network

-gallery modes 8 4 Scattering resonances and quasibound states 10 5 Cavity ring-down and light emission 13 6 modes does a cavity support? 19 9 Cavities without chaos 22 10 Chaotic cavities 25 11 Phase space2-d Microcavities: Theory and Experiments Jens U. N¨ockel Department of Physics University

Nöckelm, Jens

87

GRAPHICS PROGRAMMING Section B Java 2D  

E-print Network

followed by Java 2D and then finally Java 3D. Abstract Window Toolkit The Abstract Window Toolkit (AWT.awt.font · java.awt.geom · java.awt.print · java.awt.image.renderable To be able to draw/render onto components

Hill, Gary

88

Geometry and Categoricity  

E-print Network

Geometry and Categoricity John T. Baldwin Introduction Canonicity of Fundamental Structures Quasiminimal excellence Generalized Amalgamation and Existence Examples Model Homogeneity Zariski Structures Analytic Structures Geometry and Categoricity John T. Baldwin January 8, 2012 #12;Geometry and Categoricity

Baldwin, John T.

89

Plateau border bulimia transition: discontinuities expected in three simple experiments on 2D liquid foams  

E-print Network

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; Franois Molino; Cyprien Gay

2009-02-13

90

A finite-difference model to predict 2D depletion profiles arising from high temperature oxidation of alloys  

Microsoft Academic Search

ODIN is a 2-D finite-difference diffusion\\/interdiffusion computer model capable of predicting the solute depletion profiles evolved in binary and ternary alloys due to high temperature oxidation. The 2-D geometries that can be analysed include corners, rectangular edges and rib features. Empirical mass gain kinetics in the form of a general power law are employed as a boundary condition to define

W. M. Pragnell; H. E. Evans

2006-01-01

91

Realistic and efficient 2D crack simulation  

NASA Astrophysics Data System (ADS)

Although numerical algorithms for 2D crack simulation have been studied in Modeling and Simulation (M&S) and computer graphics for decades, realism and computational efficiency are still major challenges. In this paper, we introduce a high-fidelity, scalable, adaptive and efficient/runtime 2D crack/fracture simulation system by applying the mathematically elegant Peano-Cesaro triangular meshing/remeshing technique to model the generation of shards/fragments. The recursive fractal sweep associated with the Peano-Cesaro triangulation provides efficient local multi-resolution refinement to any level-of-detail. The generated binary decomposition tree also provides efficient neighbor retrieval mechanism used for mesh element splitting and merging with minimal memory requirements essential for realistic 2D fragment formation. Upon load impact/contact/penetration, a number of factors including impact angle, impact energy, and material properties are all taken into account to produce the criteria of crack initialization, propagation, and termination leading to realistic fractal-like rubble/fragments formation. The aforementioned parameters are used as variables of probabilistic models of cracks/shards formation, making the proposed solution highly adaptive by allowing machine learning mechanisms learn the optimal values for the variables/parameters based on prior benchmark data generated by off-line physics based simulation solutions that produce accurate fractures/shards though at highly non-real time paste. Crack/fracture simulation has been conducted on various load impacts with different initial locations at various impulse scales. The simulation results demonstrate that the proposed system has the capability to realistically and efficiently simulate 2D crack phenomena (such as window shattering and shards generation) with diverse potentials in military and civil M&S applications such as training and mission planning.

Yadegar, Jacob; Liu, Xiaoqing; Singh, Abhishek

2010-04-01

92

2D Rectangular Square Well Applet  

NSDL National Science Digital Library

This simulation shows time-dependent 2D quantum bound state wavefunctions for a rectangular hard-walled potential. Position, momentum, and energy of the states can all be viewed, with phase shown with color. Eigentstates can be selected using the energy level diagram. Multiple-energy-eigenstate wavefunctions can be created through changes in the amplitude and phase of the basis states using spinors, or through the creation of Gaussian, elliptical, or square wavefunctions with the mouse.

Falstad, Paul

2004-05-17

93

Some aspects of quantitative 2D NMR  

Microsoft Academic Search

We have studied the application of 2D HSQC for quantitative measurements and propose some improvements to the previously published Q-HSQC method. Application of CPMG-INEPT for polarization transfer period suppresses the evolution of JHH, and thus corrects the shape of the cross-peaks. The better cross-peak shape makes phase correction and integration of the cross-peaks easier. Further, the 13C resonance offset dependency

Harri Koskela; Ilkka Kilpelinen; Sami Heikkinen

2005-01-01

94

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

95

Geometry in Medias Res  

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

96

Breaking of Rotational Symmetry in Cylindrically Bounded 2D Electron Plasmas and 2D Fluids  

E-print Network

statistical mechanics of 2D incompress- ible ideal fluids can be used to understand the formation of coherent of the problem compared to tracking the detailed dynamics. Several studies have employed statistical mechanics

Marcus, Philip S.

97

3D reconstruction of a carotid bifurcation from 2D transversal ultrasound images.  

PubMed

Visualizing and analyzing the morphological structure of carotid bifurcations are important for understanding the etiology of carotid atherosclerosis, which is a major cause of stroke and transient ischemic attack. For delineation of vasculatures in the carotid artery, ultrasound examinations have been widely employed because of a noninvasive procedure without ionizing radiation. However, conventional 2D ultrasound imaging has technical limitations in observing the complicated 3D shapes and asymmetric vasodilation of bifurcations. This study aims to propose image-processing techniques for better 3D reconstruction of a carotid bifurcation in a rat by using 2D cross-sectional ultrasound images. A high-resolution ultrasound imaging system with a probe centered at 40MHz was employed to obtain 2D transversal images. The lumen boundaries in each transverse ultrasound image were detected by using three different techniques; an ellipse-fitting, a correlation mapping to visualize the decorrelation of blood flow, and the ellipse-fitting on the correlation map. When the results are compared, the third technique provides relatively good boundary extraction. The incomplete boundaries of arterial lumen caused by acoustic artifacts are somewhat resolved by adopting the correlation mapping and the distortion in the boundary detection near the bifurcation apex was largely reduced by using the ellipse-fitting technique. The 3D lumen geometry of a carotid artery was obtained by volumetric rendering of several 2D slices. For the 3D vasodilatation of the carotid bifurcation, lumen geometries at the contraction and expansion states were simultaneously depicted at various view angles. The present 3D reconstruction methods would be useful for efficient extraction and construction of the 3D lumen geometries of carotid bifurcations from 2D ultrasound images. PMID:24965564

Yeom, Eunseop; Nam, Kweon-Ho; Jin, Changzhu; Paeng, Dong-Guk; Lee, Sang-Joon

2014-12-01

98

Development of flight control system for 2D differential geometric guidance and control problem  

Microsoft Academic Search

Purpose The paper aims to provide further study on the development and analysis of flight control system for two-dimensional (2D) differential geometric (DG) guidance and control system based on the application of a set-point weighting proportional-integral-derivative (PID) controller. Design\\/methodology\\/approach The commanded angle-of-attack is developed in the time domain using the classical differential geometry theory. Then, a set-point weighting

Chaoyong Li; Wuxing Jing; Hui Wang; Zhiguo Qi

2007-01-01

99

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.

100

Interlaminar Shear Fatigue Damage Evolution of 2-D Carbon-Carbon Composites  

Microsoft Academic Search

Low-cycle and high-cycle bending fatigue experiments were conducted on 2-D woven carbon-carbon composites at room temperature to evaluate the possible evolution of damage within their complex microstructure. Since carbon-carbons are known to be weak in interlaminar shear, a 3-point bending geometry was chosen to produce high interlaminar shear stresses. This paper extends previous work by focusing on interlaminar shear fatigue,

J. C. Williams; S. W. Yurgartis; J. C. Moosbrugger

1996-01-01

101

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

102

Another solution of 2D Ising model  

SciTech Connect

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

103

2D Quantum Harmonic Oscillator Applet  

NSDL National Science Digital Library

This simulation shows time-dependent 2D quantum bound state wavefunctions for a harmonic oscillator potential. Position, momentum, angular momentum (for symmetric potentials), and energy of the states can all be viewed, with phase shown with color. Eigentstates can be selected using the energy level diagram. Multiple-energy-eigenstate wavefunctions can be created through changes in the amplitude and phase of the basis states using spinors, or through the creation of Gaussian, elliptical, or square wavefunctions with the mouse. The quantum numbers of the states are shown.

Falstad, Paul

2004-05-17

104

ESR in 2D triangular chromium lattices  

NASA Astrophysics Data System (ADS)

The spin dynamics in some two-dimensional (2D) triangular Cr-antiferromagnetic frustrated lattices, i.e. HCrO2, LiCrO2, and NaCrO2 with ordered rock-salt structure as well as the delafossite compounds CuCrO2 and AgCrO2, has been investigated by Electron Spin Resonance (ESR). On approaching the Nel temperature TN from above, the divergence of the temperature dependent linewidth is well described in terms of a Berezinskii-Kosterlitz-Thouless (BKT) like scenario due to magnetic vortex-antivortex pairing.

Hemmida, M.; Krug von Nidda, H.-A.; Loidl, A.

2010-01-01

105

2D Circular Square Well Applet  

NSDL National Science Digital Library

This simulation shows time-dependent 2D quantum bound state wavefunctions for a circular hard-walled potential. Position, momentum, angular momentum, and energy of the states can all be viewed, with phase shown with color. Eigentstates can be selected using the energy level diagram. Multiple-energy-eigenstate wavefunctions can be created through changes in the amplitude and phase of the basis states using spinors, or through the creation of Gaussian wavefunctions with the mouse. The quantum numbers of the states are shown.

Falstad, Paul

2004-05-17

106

Slab detachment - 3-D versus 1-D & 2-D  

NASA Astrophysics Data System (ADS)

Slab detachment is a geodynamic process that may affect subduction zones on Earth. This process is characterized by the detachment of a subducting slab fragment and results in a dramatic decrease of the slab pull force magnitude. As a result, slab detachment has many potential consequences for the dynamics of convergent zones such as orogens. We study three-dimensional (3-D) lateral propagation of slab detachment due to a laterally varying initial slab length with numerical simulations based on the finite element method (FEM). The slab detachment is simulatedby buoyancy-driven necking in a layer of power-law fluid embedded in a linear viscous medium. Our 3-D FEM code combines a numerical contour-line technique and a deformable Lagrangian mesh with re-meshing. With this combined method it is possible to accurately follow the initial material contours with the FEM mesh and to accurately resolve the geometrical instabilities. We are able to follow the material contour and therefore, to study the accurate slab geometry at any time. We provide a detailed description of the evolution of the slab morphology and evaluate the rates of lateral propagation of slab detachment.We compare the 3D results with the 1-D analytical solution for slab detachment of Schmalholz (2011). We further compare the 3-D results with 2-D numerical simulationsthat can be described reasonably well with the 1-D analytical solution. The fundamental differences between the3-D and 2-D slab detachment are identified and quantified. REFERENCES Schmalholz, S., 2011, A simple analytical solution for slab detachment, Earth and Planetary Science Letters 304, 45-54

von Tscharner, Marina; Duretz, Thibault; Schmalholz, Stefan

2014-05-01

107

Comprehensive 2D measurements of radiative divertor plasmas in DIII-D  

SciTech Connect

This paper presents a comparison of the total radiated power profile and impurity line emission distributions in the SOL and divertor of DIII-D. This is done for ELMing H-mode plasmas with heavy deuterium injection (Partially Detached Divertor operation, PDD) and those without deuterium puffing. Results are described from a series of dedicated experiments performed on DIII-D to systematically measure the 2-D (R,Z) structure of the divertor plasma. The discharges were designed to optimize measurements with new divertor diagnostics including a divertor Thomson scattering system. Discharge sequences were designed to produce optimized data sets against which SOL and divertor theories and simulation codes could be benchmarked. During PDD operation the regions of significant radiated power shift from the inner divertor leg and SOL to the outer leg and X-point regions. D{alpha} emission shifts from the inner strikepoint to the outer strikepoint. Carbon emissions (visible CII and CIII) shift from the inner SOL near the X-point to a distributed region from the X-point to partially down the outer leg during moderate D2 puffing. In heavy puffing discharges the carbon emission coalesces on the outer separatrix near the X-point and for very heavy puffing it appears inside the last closed flux surface above the X-point. Calibrated spectroscopic measurements indicate that hydrogenic and carbon radiation can account for all of the radiated power. L{alpha} and CIV radiation are comparable and when combined account for as much as 90% of the total radiated power along chords viewing the significant radiating regions of the outer leg.

Fenstermacher, M.E.; Wood, R.D.; Allen, S.L.; Hill, D.N. [and others

1997-07-01

108

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

109

2-d Microcavities: Theory and Experiments  

Microsoft Academic Search

An overview is provided over the physics of dielectric microcavities with\\u000anon-paraxial mode structure; examples are microdroplets and edge-emitting\\u000asemiconductor microlasers. Particular attention is given to cavities in which\\u000atwo spatial degrees of freedom are coupled via the boundary geometry. This\\u000agenerally necessitates numerical computations to obtain the electromagnetic\\u000acavity fields, and hence intuitive understanding becomes difficult. However, as\\u000ain

Jens U. Nockel; Richard K. Chang

2004-01-01

110

Astronomical Parallax 2D JS Model  

NSDL National Science Digital Library

The Astronomical Parallax 2D Javascript Model illustrates This simulation illustrates the phenomenon of parallax in astronomy. Parallax is the apparent displacement of an object relative to the background that is caused by the motion of the observer (rather than the motion of the object itself, or of the background). This simulation illustrates the parallax of an object in space that results from the Earth's rotational or orbital motions. The simulation has two different modes. The default is an Earth Rotation Mode. In this mode the simulation illustrates the parallax caused by Earth's rotation on its axis. The other mode for the simulation is Earth Orbit Mode. In this mode the simulation illustrates the parallax caused by Earth's orbit around the Sun. Now the observer moves along Earth's orbital path (shown as a blue circle with the orange Sun in the center). The bottom window shows the apparent motion of the object being observed. The Astronomical Parallax 2D JS Model was developed using the Easy Java Simulations (EJS) version 5. It is distributed as a ready-to-run html page and requires only a browser with JavaScript support.

Timberlake, Todd; Belloni, Mario

2013-09-03

111

2D packing using the Myriad framework  

NASA Astrophysics Data System (ADS)

Myriad is a framework for building networked and distributed vision systems and is described in a companion paper in this conference. Myriad allows the components of a multi-camera, multi-user vision system (web-cameras, image processing engines, intelligent device controllers, databases and the user interface terminals) to be interconnected and operated together, even if they are physically separated by many hundreds, or thousands, of kilometres. This is achieved by operating them as Internet services. The principal objective in this article is to illustrate the simplicity of harmonising visual control with an existing system using Myriad. However, packing of 2-dimensional blob-like objects is of considerable commercial importance in some industries and involves robotic handling and/or cutting. The shapes to be packed may be cut from sheet metal, glass, cloth, leather, wood, card, paper, composite board, or flat food materials. In addition, many 3D packing applications can realistically be tackled only by regarding them as multi-layer 2D applications. Using Myriad to perform 2D packing, a set of blob-like input objects ("shapes") can be digitised using a standard camera (e.g. a "webcam"). The resulting digital images are then analysed, using a separate processing engine, perhaps located on a different continent. The packing is planned by another processing system, perhaps on a third continent. Finally, the assembly is performed using a robot, usually but not necessarily, located close to the camera.

Chatburn, Luke T.; Batchelor, Bruce G.

2004-02-01

112

Lennard-Jones 2D Demon Model  

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

113

Ejs STP LJFluid2D Model  

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

114

MPS simulation of 2-D spontaneous dynamic rupture propagation  

NASA Astrophysics Data System (ADS)

In order to carry out numerical simulations of seismic motions, it is important to model earthquake faults. Several numerical methods have been developed for simulating spontaneous dynamic rupture on earthquake faults, obeying a certain fracture criterion or friction law. In such simulations, boundary conditions of dislocation are usually set on the fault. Traction-at-split-node (TSN) method (Andrews[1973]) is one of the most popular methods. So far, this method has introduced a boundary condition of dislocation mainly into a finite difference (FD) or a finite element (FE) method. However, the regular grid-based FD method is not so suitable for modeling "curved winding faults". The FE method can treat complex geometry, but it usually takes time to construct fine meshes suitable for keeping numerical accuracy in the complex geometry. Actually, faults in the nature are not always flat and have some complexities in geometry. In order to remedy this disadvantage, we develop a new method which introduces a boundary condition of dislocation into Moving Particle Semi-implicit (MPS) method. The MPS method, which is one of particle methods such as the SPH (Smoothed-Particle Hydrodynamics) method, was newly developed by Koshizuka and his colleagues in 1996 in order to simulate non-compressive fluid. Then, it has been applied for simulating deformation and wave propagation in elastic media since Chikazawa (1999). For instance, Takekawa et al. (2008) carried out simulation of elastic wave propagation and succeeded in simulating Hopkinson's effect. The MPS method is based on Lagrangian formulation and an elastic body is described as an aggregate of particles. The government equations for the elastic medium are interpreted into interactions among these particles. These interactions are equivalent to those of normal and tangential springs. Each particle interacts with its neighboring particles using a local weighting function. Therefore, it is quite easy to deal with heterogeneity and complex geometry. In this respect, MPS is similar to SPH. However, the MPS method applies simplified differential operator models solely based on a local weighted averaging process without taking the gradient of a kernel function, whereas the differential operators are applied to spatially weighting kernels in the SPH method. In this study, we introduced a boundary condition of "2-D curved winding faults" into a MPS method referring to the TSN method. To be specific, we set "fault particles" at both sides of the fault. In these particles, "interaction force" in the MPS method was substituted for "restoring force" in the TNS method. In addition we used a slip-dependent friction law which has a linear slip-weakening friction coefficient with a characteristic slip distance. In the presentation, we show the details of implementation of TSN on the earthquake fault into the MPS method, and discuss the feasibility and the accuracy of the MPS method for a 2-D spontaneous dynamic propagation problem.

Sakamoto, T.; Hirahara, K.

2009-12-01

115

Expression and Functional Analysis of CYP2D6.24, CYP2D6.26, CYP2D6.27, and CYP2D7 IsozymesS?  

PubMed Central

The objectives of this study were to compare the drug-metabolizing activity of human CYP2D6.24 (I297L), CYP2D6.26 (I369T), and CYP2D6.27 (E410K) allelic isoforms with wild-type CYP2D6.1 and to express the CYP2D7 protein derived from an indel polymorphism (CYP2D7 138delT) and investigate its possible codeine O-demethylase activity. Successful creation of individual cDNAs corresponding to CYP2D6*24 (2853 A>C), CYP2D6*26 (3277 T>C), and CYP2D6*27 (3853 G>A) allelic variants and CYP2D7 was achieved via molecular cloning. The corresponding proteins, CYP2D6.24, CYP2D6.26, CYP2D6.27, and CYP2D7, were expressed in insect cells by using a baculovirus-mediated expression system. All CYP2D proteins showed the empirical carbon monoxide difference spectra. We were surprised to find that the CYP2D7 protein was detected mainly in mitochondrial fractions, whereas all CYP2D6 allelic isoforms were present in the microsomal fraction. Furthermore, CYP2D7 did not produce any morphine from codeine. In contrast, CYP2D6.24, CYP2D6.26, and CYP2D6.27 allelic isoforms all showed active drug-metabolizing activities toward both codeine and dextromethorphan O-demethylation. Whereas CYP2D6.24 exhibited the highest intrinsic clearance in dextromethorphan O-demethylation (?6-fold higher than that by CYP2D6.1), it had the lowest enzyme efficiency in codeine O-demethylation (?50% lower than that by CYP2D6.1). Overall, the enzymatic consequences of CYP2D6 allelic isozymes are substrate dependent. These data would help preclinical and clinical assessments of the metabolic elimination of drugs that are mediated by human CYP2D enzyme. PMID:18838503

Zhang, Wei-Yan; Tu, You-Bin; Haining, Robert L.; Yu, Ai-Ming

2009-01-01

116

Geometry and Topology  

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.

117

Groovy Green Geometry!  

NSDL National Science Digital Library

Gotta Getcha some Great Goofy Geometry Games! Billy Bug is so hungry! Move him to the right coordinate so that he can eat! Make the puzzle pieces bigger or smaller to fit the puzzle in Cyberchase Geometry! If you want a definition of any geometry term.. click the word Definition ...

Nieman, Ms.

2007-11-22

118

Geometry and High School  

E-print Network

geometry texts in the U.S. came to be that way. #12;Geometry and Proof John T. Baldwin Background Hilbert. 2 Politics if the premises are political. #12;Geometry and Proof John T. Baldwin Background Hilbert Frameworks High School Curriculum Undefined terms Two kinds of definitions: 1 The `system' of basic notions

Baldwin, John T.

119

Variational regularized 2-D nonnegative matrix factorization.  

PubMed

A novel approach for adaptive regularization of 2-D nonnegative matrix factorization is presented. The proposed matrix factorization is developed under the framework of maximum a posteriori probability and is adaptively fine-tuned using the variational approach. The method enables: (1) a generalized criterion for variable sparseness to be imposed onto the solution; and (2) prior information to be explicitly incorporated into the basis features. The method is computationally efficient and has been demonstrated on two applications, that is, extracting features from image and separating single channel source mixture. In addition, it is shown that the basis features of an information-bearing matrix can be extracted more efficiently using the proposed regularized priors. Experimental tests have been rigorously conducted to verify the efficacy of the proposed method. PMID:24806120

Gao, Bin; Woo, W L; Dlay, S S

2012-05-01

120

Canard configured aircraft with 2-D nozzle  

NASA Technical Reports Server (NTRS)

A closely-coupled canard fighter with vectorable two-dimensional nozzle was designed for enhanced transonic maneuvering. The HiMAT maneuver goal of a sustained 8g turn at a free-stream Mach number of 0.9 and 30,000 feet was the primary design consideration. The aerodynamic design process was initiated with a linear theory optimization minimizing the zero percent suction drag including jet effects and refined with three-dimensional nonlinear potential flow techniques. Allowances were made for mutual interference and viscous effects. The design process to arrive at the resultant configuration is described, and the design of a powered 2-D nozzle model to be tested in the LRC 16-foot Propulsion Wind Tunnel is shown.

Child, R. D.; Henderson, W. P.

1978-01-01

121

Ising 2D Spatial Decomposition Model  

NSDL National Science Digital Library

The two-dimensional Ising Spatial Decomposition model solves the Ising model on a parallel computer by partitioning the spin lattice into rectangular subsystems of approximately equal size and assigning an independent computational thread to each subsystem. Because a lattice site only interacts with its nearest neighbors, sites in the interior of a subsystem only interact with sites in the same subsystem and the solution algorithm can be applied without interference between threads. Border cells, however, can interact with cells in neighboring subsystems and this interaction must be synchronized.   This model uses a parallel region to perform the computation. A second window displays a histogram showing how may spin flips are performed by each thread. The Ising 2D Spatial Decomposition 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 jar file will run the program if Java is installed.

Christian, Wolfgang

2013-10-14

122

Numerically robust geometry engine for compound solid geometries  

NASA Astrophysics Data System (ADS)

Monte Carlo programs heavily rely on a fast and numerically robust solid geometry engines. However the success of solid modeling, depends on facilities for specifying and editing parameterized models through a user-friendly graphical front-end. Such a user interface has to be fast enough in order to be interactive for 2D and/or 3D displays, but at the same time numerically robust in order to display possible modeling errors at real time that could be critical for the simulation. The graphical user interface "flair"(1) for FLUKA(2,3) currently employs such an engine where special emphasis has been given on being fast and numerically robust. The numerically robustness is achieved by a novel method of estimating the floating precision of the operations, which dynamically adapts all the decision operations accordingly. Moreover a predictive caching mechanism is ensuring that logical errors in the geometry description are found online, without compromising the processing time by checking all regions.

Vlachoudis, V.; Sinuela-Pastor, D.

2014-06-01

123

2D axisymmetric analysis of SRM ignition transient  

NASA Technical Reports Server (NTRS)

To analyze ignition transient of Space Shuttle solid rocket motor, a transient two-dimensional numerical model based on turbulent compressible Navier-Stokes equations in a generalized coordinate system was developed. One-dimensional numerical models (Peretz et al., 1973; Han, 1992; Pardue and Han, 1992) with empirical correlations data obtained from steady turbulent boundary layer flows agrees reasonably well with test rocket data by adjusting a few parameters. However, a 1D model can not provide a physical insight into the complex multidimensional thermal fields and flowfields in the chamber and the converging-diverging rocket nozzle. As an interim step, a 2D model was developed and compared with test data. A modified version of SIMPLE algorithm was used for the numerical model, and the standard k-epsilon model with a wall function was used for turbulence closure. Transient flowfields and thermal fields in the combustion chamber and the attached nozzle were obtained for a selected rocket geometry and propellant. Transient behaviors of the flow and thermal fields were analyzed, and were found to be in good agreement with physical expectations.

Bai, S. D.; Han, Samuel S.; Pardue, B. A.

1993-01-01

124

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

125

A new inversion method for (T2, D) 2D NMR logging and fluid typing  

NASA Astrophysics Data System (ADS)

One-dimensional nuclear magnetic resonance (1D NMR) logging technology has some significant limitations in fluid typing. However, not only can two-dimensional nuclear magnetic resonance (2D NMR) provide some accurate porosity parameters, but it can also identify fluids more accurately than 1D NMR. In this paper, based on the relaxation mechanism of (T2, D) 2D NMR in a gradient magnetic field, a hybrid inversion method that combines least-squares-based QR decomposition (LSQR) and truncated singular value decomposition (TSVD) is examined in the 2D NMR inversion of various fluid models. The forward modeling and inversion tests are performed in detail with different acquisition parameters, such as magnetic field gradients (G) and echo spacing (TE) groups. The simulated results are discussed and described in detail, the influence of the above-mentioned observation parameters on the inversion accuracy is investigated and analyzed, and the observation parameters in multi-TE activation are optimized. Furthermore, the hybrid inversion can be applied to quantitatively determine the fluid saturation. To study the effects of noise level on the hybrid method and inversion results, the numerical simulation experiments are performed using different signal-to-noise-ratios (SNRs), and the effect of different SNRs on fluid typing using three fluid models are discussed and analyzed in detail.

Tan, Maojin; Zou, Youlong; Zhou, Cancan

2013-02-01

126

2-D Animation's Not Just for Mickey Mouse.  

ERIC Educational Resources Information Center

Discusses characteristics of two-dimensional (2-D) animation; highlights include character animation, painting issues, and motion graphics. Sidebars present Silicon Graphics animations tools and 2-D animation programs for the desktop computer. (DGM)

Weinman, Lynda

1995-01-01

127

H? state estimation of 2D discrete systems  

Microsoft Academic Search

This paper deals with H? state estimation of two-dimensional (2D) linear discrete time-invariant systems described by a 2D local state-space Fornasini-Marchesini second model. Several versions of the bounded real lemma of the 2D discrete systems are established. The 2D bounded real lemma allows one to solve the finite horizon H? state estimation problems using a Riccati difference equation. Further, a

C. Du; L. Xie; Y. C. Soh

1999-01-01

128

Fast approximate Duplicate Detection for 2D-NMR Spectra  

E-print Network

Fast approximate Duplicate Detection for 2D-NMR Spectra Bj¨orn Egert1 , Steffen Neumann1. In contrast to 1D-NMR spectra, 2D-NMR spectra correlate the chemical shifts of 1 H and 13 C simultaneously a definition of duplicates with the desired robustness properties mandatory for 2D-NMR experiments. A major

Hinneburg, Alexander

129

Communication Interlaced Fourier transformation of ultrafast 2D NMR data  

E-print Network

Communication Interlaced Fourier transformation of ultrafast 2D NMR data Mor Mishkovsky, Lucio in ultrafast 2D NMR is discussed and exemplified, based on the interlaced Fourier transformation. This approach- and heteronuclear ultrafast 2D NMR acquisitions, and found systematically fulfilled. The robustness and conditions

Frydman, Lucio

130

Communication Arrayed acquisition of 2D exchange NMR spectra within  

E-print Network

Communication Arrayed acquisition of 2D exchange NMR spectra within a single scan experiment Boaz time. Further, since 2D exchange NMR spectra can nowadays be themselves collected within one scan evolution, particularly with the advent of 2D NMR spectroscopy [11,12]. Signals Sðt1; t2?

Frydman, Lucio

131

Communication Single-scan 2D DOSY NMR spectroscopy  

E-print Network

Communication Single-scan 2D DOSY NMR spectroscopy Yoav Shrot, Lucio Frydman * Department. Introduction Two-dimensional nuclear magnetic resonance (2D NMR) plays a fundamental role in expanding on the principles and applications of the resulting 2D diffusion-shift NMR correlation experiment, have been given

Frydman, Lucio

132

Restoring 2D content from distorted documents.  

PubMed

This paper presents a framework to restore the 2D content printed on documents in the presence of geometric distortion and non-uniform illumination. Compared with textbased document imaging approaches that correct distortion to a level necessary to obtain sufficiently readable text or to facilitate optical character recognition (OCR), our work targets nontextual documents where the original printed content is desired. To achieve this goal, our framework acquires a 3D scan of the document's surface together with a high-resolution image. Conformal mapping is used to rectify geometric distortion by mapping the 3D surface back to a plane while minimizing angular distortion. This conformal "deskewing" assumes no parametric model of the document's surface and is suitable for arbitrary distortions. Illumination correction is performed by using the 3D shape to distinguish content gradient edges from illumination gradient edges in the high-resolution image. Integration is performed using only the content edges to obtain a reflectance image with significantly less illumination artifacts. This approach makes no assumptions about light sources and their positions. The results from the geometric and photometric correction are combined to produce the final output. PMID:17848773

Brown, Michael S; Sun, Mingxuan; Yang, Ruigang; Yun, Lin; Seales, W Brent

2007-11-01

133

On 2D impurity radiation fronts  

NASA Astrophysics Data System (ADS)

In [1] a strongly radiated impurity radiation front in magnetized plasma was investigated with simple 2D reaction-diffusion equation where perpendicular and parallel heat conduction coefficients were assumed to be the functions of temperature, K_allel=K_allel (T)>> K_?= K_?(T). It was shown that when the ratio K_allel (T)/K_? (T) increases with increasing T, a strongly radiated V-shaped radiation front (spread along the magnetic field lines) can be formed and perpendicular transport plays a key role in the magnitude of the radiation loss in spite of the inequality K_allel >> K_?. Here we generalize the results of Ref. 1 to the case when K_? depends on both temperature and radial derivative of T, which model anomalous perpendicular heat transport in magnetized plasmas. We present a criterion of V-shaped front formation and consider structural stability of such front. [1] S.I. Krasheninnikov, A.A. Batishcheva, D.J. Sigmar, EPS-97. *Also at Kurchatov Institute, Russia

Simakov, A. M.; Krasheninnikov, S. I.

1997-11-01

134

CSY3019 -Graphics Programming Assignment 1: Development of 2D/3D graphics software: Java 2D (50%)  

E-print Network

CSY3019 - Graphics Programming Assignment 1: Development of 2D/3D graphics software: Java 2D (50/demonstration The viva/demonstration of the developed application will be conducted within the timetabled session

Hill, Gary

135

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

2014-06-01

136

The Geometry Junkyard  

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.

137

Generalized Khler Geometry  

NASA Astrophysics Data System (ADS)

Generalized Khler geometry is the natural analogue of Khler 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 Khler 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 Khler geometry.

Gualtieri, Marco

2014-10-01

138

2D/3D Visual Tracker for Rover Mast  

NASA Technical Reports Server (NTRS)

A visual-tracker computer program controls an articulated mast on a Mars rover to keep a designated feature (a target) in view while the rover drives toward the target, avoiding obstacles. Several prior visual-tracker programs have been tested on rover platforms; most require very small and well-estimated motion between consecutive image frames a requirement that is not realistic for a rover on rough terrain. The present visual-tracker program is designed to handle large image motions that lead to significant changes in feature geometry and photometry between frames. When a point is selected in one of the images acquired from stereoscopic cameras on the mast, a stereo triangulation algorithm computes a three-dimensional (3D) location for the target. As the rover moves, its body-mounted cameras feed images to a visual-odometry algorithm, which tracks two-dimensional (2D) corner features and computes their old and new 3D locations. The algorithm rejects points, the 3D motions of which are inconsistent with a rigid-world constraint, and then computes the apparent change in the rover pose (i.e., translation and rotation). The mast pan and tilt angles needed to keep the target centered in the field-of-view of the cameras (thereby minimizing the area over which the 2D-tracking algorithm must operate) are computed from the estimated change in the rover pose, the 3D position of the target feature, and a model of kinematics of the mast. If the motion between the consecutive frames is still large (i.e., 3D tracking was unsuccessful), an adaptive view-based matching technique is applied to the new image. This technique uses correlation-based template matching, in which a feature template is scaled by the ratio between the depth in the original template and the depth of pixels in the new image. This is repeated over the entire search window and the best correlation results indicate the appropriate match. The program could be a core for building application programs for systems that require coordination of vision and robotic motion.

Bajracharya, Max; Madison, Richard W.; Nesnas, Issa A.; Bandari, Esfandiar; Kunz, Clayton; Deans, Matt; Bualat, Maria

2006-01-01

139

Inhibition of human cytochrome P450 2D6 (CYP2D6) by methadone.  

PubMed

1. In microsomes prepared from three human livers, methadone competitively inhibited the O-demethylation of dextromethorphan, a marker substrate for CYP2D6. The apparent Ki value of methadone ranged from 2.5 to 5 microM. 2. Two hundred and fifty-two (252) white Caucasians, including 210 unrelated healthy volunteers and 42 opiate abusers undergoing treatment with methadone were phenotyped using dextromethorphan as the marker drug. Although the frequency of poor metabolizers was similar in both groups, the extensive metabolizers among the opiate abusers tended to have higher O-demethylation metabolic ratios and to excrete less of the dose as dextromethorphan metabolites than control extensive metabolizer subjects. These data suggest inhibition of CYP2D6 by methadone in vivo as well. 3. Because methadone is widely used in the treatment of opiate abuse, inhibition of CYP2D6 activity in these patients might contribute to exaggerated response or unexpected toxicity from drugs that are substrates of this enzyme. PMID:8448065

Wu, D; Otton, S V; Sproule, B A; Busto, U; Inaba, T; Kalow, W; Sellers, E M

1993-01-01

140

A Planar Quantum Transistor Based on 2D-2D Tunneling in Double Quantum Well Heterostructures  

SciTech Connect

We report on our work on the double electron layer tunneling transistor (DELTT), based on the gate-control of two-dimensional -- two-dimensional (2D-2D) tunneling in a double quantum well heterostructure. While previous quantum transistors have typically required tiny laterally-defined features, by contrast the DELTT is entirely planar and can be reliably fabricated in large numbers. We use a novel epoxy-bond-and-stop-etch (EBASE) flip-chip process, whereby submicron gating on opposite sides of semiconductor epitaxial layers as thin as 0.24 microns can be achieved. Because both electron layers in the DELTT are 2D, the resonant tunneling features are unusually sharp, and can be easily modulated with one or more surface gates. We demonstrate DELTTs with peak-to-valley ratios in the source-drain I-V curve of order 20:1 below 1 K. Both the height and position of the resonant current peak can be controlled by gate voltage over a wide range. DELTTs with larger subband energy offsets ({approximately} 21 meV) exhibit characteristics that are nearly as good at 77 K, in good agreement with our theoretical calculations. Using these devices, we also demonstrate bistable memories operating at 77 K. Finally, we briefly discuss the prospects for room temperature operation, increases in gain, and high-speed.

Baca, W.E.; Blount, M.A.; Hafich, M.J.; Lyo, S.K.; Moon, J.S.; Reno, J.L.; Simmons, J.A.; Wendt, J.R.

1998-12-14

141

Topology and Geometry Software  

NSDL National Science Digital Library

The Topology and Geometry Software site provides downloads for games and interactive simulations. These help the user to understand finitely infinite systems. Many are available in multiple languages.

Weeks, Jeff

2009-06-15

142

Conformation of self-assembled porphyrin dimers in liposome vesicles by phase-modulation 2D fluorescence spectroscopy.  

PubMed

By applying a phase-modulation fluorescence approach to 2D electronic spectroscopy, we studied the conformation-dependent exciton coupling of a porphyrin dimer embedded in a phospholipid bilayer membrane. Our measurements specify the relative angle and separation between interacting electronic transition dipole moments and thus provide a detailed characterization of dimer conformation. Phase-modulation 2D fluorescence spectroscopy (PM-2D FS) produces 2D spectra with distinct optical features, similar to those obtained using 2D photon-echo spectroscopy. Specifically, we studied magnesium meso tetraphenylporphyrin dimers, which form in the amphiphilic regions of 1,2-distearoyl-sn-glycero-3-phosphocholine liposomes. Comparison between experimental and simulated spectra show that although a wide range of dimer conformations can be inferred by either the linear absorption spectrum or the 2D spectrum alone, consideration of both types of spectra constrain the possible structures to a "T-shaped" geometry. These experiments establish the PM-2D FS method as an effective approach to elucidate chromophore dimer conformation. PMID:21940499

Lott, Geoffrey A; Perdomo-Ortiz, Alejandro; Utterback, James K; Widom, Julia R; Aspuru-Guzik, Aln; Marcus, Andrew H

2011-10-01

143

Conformation of self-assembled porphyrin dimers in liposome vesicles by phase-modulation 2D fluorescence spectroscopy  

PubMed Central

By applying a phase-modulation fluorescence approach to 2D electronic spectroscopy, we studied the conformation-dependent exciton coupling of a porphyrin dimer embedded in a phospholipid bilayer membrane. Our measurements specify the relative angle and separation between interacting electronic transition dipole moments and thus provide a detailed characterization of dimer conformation. Phase-modulation 2D fluorescence spectroscopy (PM-2D FS) produces 2D spectra with distinct optical features, similar to those obtained using 2D photon-echo spectroscopy. Specifically, we studied magnesium meso tetraphenylporphyrin dimers, which form in the amphiphilic regions of 1,2-distearoyl-sn-glycero-3-phosphocholine liposomes. Comparison between experimental and simulated spectra show that although a wide range of dimer conformations can be inferred by either the linear absorption spectrum or the 2D spectrum alone, consideration of both types of spectra constrain the possible structures to a T-shaped geometry. These experiments establish the PM-2D FS method as an effective approach to elucidate chromophore dimer conformation. PMID:21940499

Lott, Geoffrey A.; Perdomo-Ortiz, Alejandro; Utterback, James K.; Widom, Julia R.; Aspuru-Guzik, Aln; Marcus, Andrew H.

2011-01-01

144

2D gasdynamic simulation of the kinetics of an oxygen-iodine laser with electric-discharge generation of singlet oxygen  

SciTech Connect

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 and their mixing with the iodine-containing gas. The main processes affecting the dynamics of the gas temperature and gain are revealed. The simulation results obtained using the 2D model agree well with the experimental data on the mixture gain. A subsonic oxygen-iodine laser in which singlet oxygen is generated by a 350 W transverse RF discharge excited in an oxygen flow at a pressure P = 10 Torr and the discharge tube wall is covered with mercury oxide is simulated. The simulated mixing system is optimized in terms of the flow rate and the degree of preliminary dissociation of the iodine flow. The optimal regime of continuous operation of a subsonic electric-discharge oxygen-iodine laser is found.

Chukalovsky, A. A.; Rakhimova, T. V.; Klopovsky, K. S.; Mankelevich, Yu. A.; Proshina, O. V. [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)

2011-03-15

145

A large 2D PSD for thermal neutron detection  

SciTech Connect

A 2D PSD based on a MWPC has been constructed for a small angle neutron scattering instrument. The active area of the detector was 640 x 640 mm{sup 2}. To meet the specifications for neutron detection efficiency and spatial resolution, and to minimize parallax, the gas mixture was 190 kPa {sup 3}He plus 100 kPa CF{sub 4} and the active volume had a thickness of 30 mm. The design maximum neutron count-rate of the detector was 10{sup 5} events per second. The (calculated) neutron detection efficiency was 60% for 2{angstrom} neutrons and the (measured) neutron energy resolution on the anode grid was typically 20% (fwhm). The location of a neutron detection event within the active area was determined using the wire-by-wire method: the spatial resolution (5 x 5 mm{sup 2}) was thereby defined by the wire geometry. A 16 channel charge-sensitive preamplifier/amplifier/comparator module has been developed with a channel sensitivity of 0.1 V/fC, noise linewidth of 0.4 fC (fwhm) and channel-to-channel cross-talk of less than 5%. The Proportional Counter Operating System (PCOS III) (LeCroy Corp USA) was used for event encoding. The ECL signals produced by the 16 channel modules were latched in PCOS III by a trigger pulse from the anode and the fast encoders produce a position and width for each event. The information was transferred to a UNIX workstation for accumulation and online display.

Knott, R.B.; Watt, G.; Boldeman, J.W. [Australian Nuclear Science and Technology Organization, Menai, New South Wales (Australia). Physics Div.; Smith, G.C. [Brookhaven National Lab., Upton, NY (United States). Instrumentation Div.

1996-12-31

146

Geometry + Technology = Proof  

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

147

Twistors to twisted geometries  

SciTech Connect

In a previous paper we showed that the phase space of loop quantum gravity on a fixed graph can be parametrized in terms of twisted geometries, quantities describing the intrinsic and extrinsic discrete geometry of a cellular decomposition dual to the graph. Here we unravel the origin of the phase space from a geometric interpretation of twistors.

Freidel, Laurent [Perimeter Institute for Theoretical Physics, 31 Caroline Street N, ON N2L 2Y5, Waterloo (Canada); Speziale, Simone [Centre de Physique Theorique, CNRS-Luminy Case 907, 13288 Marseille Cedex 09 (France)

2010-10-15

148

Near wall plasma simulation using penalization technique with the transport code SOLEDGE2D-EIRENE  

NASA Astrophysics Data System (ADS)

In order to model plasma interaction with full complexity of the geometry of PFCs, an immersed method to impose boundary conditions has been implemented in the transport code SOLEDGE2D. This penalization technique has proven to properly recover Bohm boundary conditions, including supersonic solutions at the sheath entrance. The role of the ionization source has been taken into account by coupling SOLEDGE2D with the 3D kinetic neutral code EIRENE. Density regimes are properly recovered and major differences between core located and divertor located ionization source regimes are emphasized. One also presents main chamber wall recycling regime simulations that can now be addressed with simulations of the entire edge plasma up to the wall.

Bufferand, H.; Bensiali, B.; Bucalossi, J.; Ciraolo, G.; Genesio, P.; Ghendrih, Ph.; Marandet, Y.; Paredes, A.; Schwander, F.; Serre, E.; Tamain, P.

2013-07-01

149

Communication: Determining the lowest-energy isomer of Au8: 2D, or not 2D  

NASA Astrophysics Data System (ADS)

A parallel numerical derivative code, combined with parallel implementation of the coupled-cluster method with singles, doubles, and non-iterative triples (CCSD(T)), is used to optimize the geometries of the low-energy structures of the Au8 particle. The effects of geometry relaxation at the CCSD(T) level and the combined effects of the basis set and core-valence correlations are examined and the results are compared with the corresponding second-order Mller-Plesset perturbation theory calculations. The highest-level computations, in which the single-point CCSD(T) calculations employing the correlation-consistent basis set of the cc-pVTZ quality and the associated relativistic effective core potential (ECP), both optimized for gold, and correlating the 5d106s1 valence and 5s25p6 semi-core electrons, are combined with the geometrical information obtained with the corresponding CCSD(T)/cc-pVDZ/ECP approach, favor the planar configuration, with the next three non-planar structures separated by 4-6 kcal/mol. In agreement with the earlier work, smaller-basis set CCSD(T) computations provide unreliable results for the relative energetics, even when the geometries are optimized at the CCSD(T) level.

Hansen, Jared A.; Piecuch, Piotr; Levine, Benjamin G.

2013-09-01

150

Communication: Determining the lowest-energy isomer of Au8: 2D, or not 2D.  

PubMed

A parallel numerical derivative code, combined with parallel implementation of the coupled-cluster method with singles, doubles, and non-iterative triples (CCSD(T)), is used to optimize the geometries of the low-energy structures of the Au8 particle. The effects of geometry relaxation at the CCSD(T) level and the combined effects of the basis set and core-valence correlations are examined and the results are compared with the corresponding second-order Mller-Plesset perturbation theory calculations. The highest-level computations, in which the single-point CCSD(T) calculations employing the correlation-consistent basis set of the cc-pVTZ quality and the associated relativistic effective core potential (ECP), both optimized for gold, and correlating the 5d(10)6s(1) valence and 5s(2)5p(6) semi-core electrons, are combined with the geometrical information obtained with the corresponding CCSD(T)/cc-pVDZ/ECP approach, favor the planar configuration, with the next three non-planar structures separated by 4-6 kcal/mol. In agreement with the earlier work, smaller-basis set CCSD(T) computations provide unreliable results for the relative energetics, even when the geometries are optimized at the CCSD(T) level. PMID:24028093

Hansen, Jared A; Piecuch, Piotr; Levine, Benjamin G

2013-09-01

151

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

152

Holographic Entanglement Entropy from 2d CFT: Heavy States and Local Quenches  

E-print Network

We consider the entanglement entropy in 2d conformal field theory in a class of excited states produced by the insertion of a heavy local operator. These include both high-energy eigenstates of the Hamiltonian and time-dependent local quenches. We compute the universal contribution from the stress tensor to the single interval Renyi entropies and entanglement entropy, and conjecture that this dominates the answer in theories with a large central charge and a sparse spectrum of low-dimension operators. The resulting entanglement entropies agree precisely with holographic calculations in three-dimensional gravity. High-energy eigenstates are dual to microstates of the BTZ black hole, so the corresponding holographic calculation is a geodesic length in the black hole geometry; agreement between these two answers demonstrates that entanglement entropy thermalizes in individual microstates of holographic CFTs. For local quenches, the dual geometry is a highly boosted black hole or conical defect. On the CFT side, ...

Asplund, Curtis T; Galli, Federico; Hartman, Thomas

2014-01-01

153

Space-Time Foam in 2D and the Sum Over Topologies  

NASA Astrophysics Data System (ADS)

It is well-known that the sum over topologies in quantum gravity is ill-defined, due to a super-exponential growth of the number of geometries as a function of the space-time volume, leading to a badly divergent gravitational path integral. Not even in dimension 2, where a non-perturbative quantum gravity theory can be constructed explicitly from a (regularized) path integral, has this problem found a satisfactory solution. In the present work, we extend a previous 2d Lorentzian path integral, regulated in terms of Lorentzian random triangulations, to include space-times with an arbitrary number of handles. We show that after the imposition of physically motivated causality constraints, the combined sum over geometries and topologies is well-defined and possesses a continuum limit which yields a concrete model of space-time foam in two dimensions.

Loll, R.; Westra, W.

2003-10-01

154

Native American geometry  

NSDL National Science Digital Library

This website focuses on Native American use of the physical, proportional geometry that originates from the simple circle. Aimed at 4th to 9th grade teachers, the site is divided into four sections: foundations, anthropology, designs, and education. It was selected by Britannica.com, February 2000, as a best Internet site. Other keywords: geometric shapes, geometric constructions, proportional geometry, proportional constants, polygons, hexagons, equilateral triangles, dodecagons, squares, octagons, connect the dot, art, square roots, irrational numbers, non-random geometry. (Includes about 25 relevant website links and 50 published references)

2007-12-12

155

Genetic Polymorphism in Cytochrome P450 2D6 (CYP2D6): Population Distribution of CYP2D6 Activity  

Microsoft Academic Search

Cytochrome P-450 2D6 (CYP2D6) is involved in the metabolism of many therapeutic drugs even though the enzyme represents a small proportion of the total CYP content of human liver. In vivo phenotyping with probe drug substrates such as debrisoquine and dextromethorphan showed a clear separation between poor metabolizers (PM) and extensive metabolizers (EM). This polymorphism may affect susceptibility to environmental

Patricia Neafsey; Gary Ginsberg; Dale Hattis; Babasaheb Sonawane

2009-01-01

156

Optical design of wavelength selective CPVT system with 3D/2D hybrid concentration  

NASA Astrophysics Data System (ADS)

Optical design of a concentrating photovoltaic/thermal (CPVT) system is carried out. Using wavelength-selective optics, the system demonstrates 3-D concentration onto a solar cell and 2-D concentration onto a thermal receiver. Characteristics of the two types of concentrator systems are examined with ray-tracing analysis. The first system is a glazed mirror-based concentrator system mounted on a 2-axis pedestal tracker. The size of the secondary optical element is minimized to decrease the cost of the system, and it has a wavelength-selective function for performing 3-D concentration onto a solar cell and 2-D concentration onto a thermal receiver. The second system is a non-glazed beamdown concentrator system containing parabolic mirrors in the lower part. The beam-down selective mirror performs 3-D concentration onto a solar cell placed above the beam-down selective mirror, and 2-D concentration down to a thermal receiver placed at the bottom level. The system is mounted on a two-axis carousel tracker. A parametric study is performed for those systems with different geometrical 2-D/3-D concentration ratios. Wavelength-selective optics such as hot/cold mirrors and spectrum-splitting technologies are taken into account in the analysis. Results show reduced heat load on the solar cell and increased total system efficiency compared to a non-selective CPV system. Requirements for the wavelength-selective properties are elucidated. It is also shown that the hybrid concept with 2-D concentration onto a thermal receiver and 3-D concentration onto a solar cell has an advantageous geometry because of the high total system efficiency and compatibility with the piping arrangement of the thermal receiver.

Ahmad, N.; Ijiro, T.; Yamada, N.; Kawaguchi, T.; Maemura, T.; Ohashi, H.

2012-10-01

157

Gingerbread-House Geometry.  

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

158

Geometry (MathPages)  

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

159

An Incompressible 2D Didactic Model with Singularity and Explicit Solutions of the 2D Boussinesq Equations  

NASA Astrophysics Data System (ADS)

We give an example of a well posed, finite energy, 2D incompressible active scalar equation with the same scaling as the surface quasi-geostrophic equation and prove that it can produce finite time singularities. In spite of its simplicity, this seems to be the first such example. Further, we construct explicit solutions of the 2D Boussinesq equations whose gradients grow exponentially in time for all time. In addition, we introduce a variant of the 2D Boussinesq equations which is perhaps a more faithful companion of the 3D axisymmetric Euler equations than the usual 2D Boussinesq equations.

Chae, Dongho; Constantin, Peter; Wu, Jiahong

2014-09-01

160

SOC and Fractal Geometry  

NASA Astrophysics Data System (ADS)

When Mandelbrot, the father of modern fractal geometry, made this seemingly obvious statement he was trying to show that we should move out of our comfortable Euclidean space and adopt a fractal approach to geometry. The concepts and mathematical tools of fractal geometry provides insight into natural physical systems that Euclidean tools cannot do. The benet from applying fractal geometry to studies of Self-Organized Criticality (SOC) are even greater. SOC and fractal geometry share concepts of dynamic n-body interactions, apparent non-predictability, self-similarity, and an approach to global statistics in space and time that make these two areas into naturally paired research techniques. Further, the iterative generation techniques used in both SOC models and in fractals mean they share common features and common problems. This chapter explores the strong historical connections between fractal geometry and SOC from both a mathematical and conceptual understanding, explores modern day interactions between these two topics, and discusses how this is likely to evolve into an even stronger link in the near future.

McAteer, R. T. J.

2013-06-01

161

CMS Geometry Through 2020  

NASA Astrophysics Data System (ADS)

CMS faces real challenges with upgrade of the CMS detector through 2020 and beyond. One of the challenges, from the software point of view, is managing upgrade simulations with the same software release as the 2013 scenario. We present the CMS geometry description software model, its integration with the CMS event setup and core software. The CMS geometry configuration and selection is implemented in Python. The tools collect the Python configuration fragments into a script used in CMS workflow. This flexible and automated geometry configuration allows choosing either transient or persistent version of the same scenario and specific version of the same scenario. We describe how the geometries are integrated and validated, and how we define and handle different geometry scenarios in simulation and reconstruction. We discuss how to transparently manage multiple incompatible geometries in the same software release. Several examples are shown based on current implementation assuring consistent choice of scenario conditions. The consequences and implications for multiple/different code algorithms are discussed.

Osborne, I.; Brownson, E.; Eulisse, G.; Jones, C. D.; Lange, D. J.; Sexton-Kennedy, E.

2014-06-01

162

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

163

2D Corotational Beam Formulation by Louie L. Yaw  

E-print Network

1 2D Corotational Beam Formulation by Louie L. Yaw Walla Walla University November 30, 2009 key words: geometrically nonlinear analysis, 2d corotational beam, variationally consistent, load control Introduction This article presents information necessary for a simple two-dimensional corotational beam

Yaw, Louis L.

164

Process physics determining 2-D impurity profiles in VLSI devices  

Microsoft Academic Search

Physically robust diffusion models are required to simulate two-dimensional (2D) impurity profiles in VLSI devices. The accuracy of the initial dopant profiles severely limits the predictive capability of 2D device simulators. Historically, the most successful diffusion models have been based on point defect mechanisms involving either vacancy or in terstitial assisted diffusion. It is clear that the local con centration

P. B. Griffin; J. D. Plummer

1986-01-01

165

2D-Shape Analysis Using Conformal Mapping  

Microsoft Academic Search

The study of 2D shapes and their similarities is a central problem in the field of vision. It arises in particular from the task of classifying and recognizing objects from their observed silhouette. Defining natural distances between 2D shapes cre- ates a metric space of shapes, whose mathematical structure is inherently relevant to the classification task. One intriguing metric space

Eitan Sharon; David Mumford

2004-01-01

166

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

E-print Network

2D pictures of patients each being affected with one of 10 syndromes (fragile X syndrome; Cornelia de Lange syndrome; Williams­Beuren syndrome; Prader­Willi syndrome; Mucopolysaccharidosis type IIIARTICLE Syndrome identification based on 2D analysis software Stefan Boehringer*,1 , Tobias Vollmar

Würtz, Rolf P.

167

CYP2D6 polymorphism in patients with eating disorders.  

PubMed

CYP2D6 polymorphism is associated with variability in drug response, endogenous metabolism (that is, serotonin), personality, neurocognition and psychopathology. The relationship between CYP2D6 genetic polymorphism and the risk of eating disorders (ED) was analyzed in 267 patients with ED and in 285 controls. A difference in the CYP2D6 active allele distribution was found between these groups. Women carrying more than two active genes (ultrarapid metabolizers) (7.5 vs 4.6%) or two (67 vs 58.9%) active genes were more frequent among patients with ED, whereas those with one (20.6 vs 30.2%) or zero active genes (4.9 vs 6.3%) were more frequent among controls (P<0.05). Although further research is needed, present findings suggest an association between CYP2D6 and ED. CYP2D6 allele distribution in patients with ED seems related to increased enzyme activity. PMID:20877302

Peas-Lled, E M; Dorado, P; Agera, Z; Gratacs, M; Estivill, X; Fernndez-Aranda, F; Llerena, A

2012-04-01

168

Regulation of ligands for the NKG2D activating receptor  

PubMed Central

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

169

Guidelines for bioanalytical 2D chromatography method development and implementation.  

PubMed

2D chromatography is a rapidly evolving, very powerful tool for bioanalysis. Advances in the theory of 2D separations, instrument technology and data analysis strategies continue to complement each other and advance the state of the art. Separations of complex mixtures of biomolecules yielding several hundred peaks in practical analysis times (tens of minutes to several hours) are relatively common. However, this level of performance largely remains the domain of expert researchers and several practical limitations stand in the way of more widespread use of 2D separations among practitioners. While off-the-shelf instruments are increasing in number, the most effective 2D instruments are often home-built, and analysis of the extremely rich datasets resulting from these separations continues to be a serious bottleneck in the overall workflow. This review summarizes some of the most serious challenges in method development and describes best practices to help guide users in designing effective 2D separations for bioanalysis. PMID:21083124

Stoll, Dwight R

2010-01-01

170

Integrable Background Geometries  

NASA Astrophysics Data System (ADS)

This work has its origins in an attempt to describe systematically the integrable geometries and gauge theories in dimensions one to four related to twistor theory. In each such dimension, there is a nondegenerate integrable geometric structure, governed by a nonlinear integrable differential equation, and each solution of this equation determines a background geometry on which, for any Lie group G, an integrable gauge theory is defined. In four dimensions, the geometry is selfdual conformal geometry and the gauge theory is selfdual Yang-Mills theory, while the lower-dimensional structures are nondegenerate (i.e., non-null) reductions of this. Any solution of the gauge theory on a k-dimensional geometry, such that the gauge group H acts transitively on an ?-manifold, determines a (k+?)-dimensional geometry (k+??4) fibering over the k-dimensional geometry with H as a structure group. In the case of an ?-dimensional group H acting on itself by the regular representation, all (k+?)-dimensional geometries with symmetry group H are locally obtained in this way. This framework unifies and extends known results about dimensional reductions of selfdual conformal geometry and the selfdual Yang-Mills equation, and provides a rich supply of constructive methods. In one dimension, generalized Nahm equations provide a uniform description of four pole isomonodromic deformation problems, and may be related to the {SU}(?) Toda and dKP equations via a hodograph transformation. In two dimensions, the {Diff}(S^1) Hitchin equation is shown to be equivalent to the hyperCR Einstein-Weyl equation, while the {SDiff}(?^2) Hitchin equation leads to a Euclidean analogue of Plebanski's heavenly equations. In three and four dimensions, the constructions of this paper help to organize the huge range of examples of Einstein-Weyl and selfdual spaces in the literature, as well as providing some new ! ones. The nondegenerate reductions have a long ancestry. More ! recently , degenerate or null reductions have attracted increased interest. Two of these reductions and their gauge theories (arguably, the two most significant) are also described.

Calderbank, David M. J.

2014-03-01

171

Foundations of Dynamic Geometry  

E-print Network

Although it is known that Calvin and Hobbes tell the truth about life, I was surprised that Bill Watterson knew in 1988 what Jrgen Richter-Gebert and I had to learn ten years later: Sometimes it is necessary to use imaginary numbers even for seemingly trivial tasks. This thesis shall explain the details of a method called complex tracing, and lay the foundations of Dynamic Geometry, a new field of research that opened up after we solved the continuity problem for interactive geometry software. I came into this project right after I decided not to write my thesis on Cinderella, the interactive geometry software which at that time was a project of Jrgen Richter-Gebert and Henry Crapo, but on neighborly polytopes. After the first few weeks of implementing the new version of Cinderella in Java I understood why it is really hard to write just another geometry software. I had to try to implement a dynamic geometry software in order to understand why it is difficult to create a software that behaves as expected. It needs a mathematical theory, and it was not clear to us what to do three years ago. It was in early 1998 when we had our ultimate break-through. The time since then was spent for the implementation of the theory, and it is nice to see that this implementation

Ulrich Kortenkamp

1999-01-01

172

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

173

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

PubMed Central

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.

Chen, Yen-Pei

2014-01-01

174

Neutrino masses, dominant neutrinoless double beta decay, and observable lepton flavor violation in left-right models and SO(10) grand unification with low mass W R , Z R bosons  

NASA Astrophysics Data System (ADS)

While the detection of W R-boson at the Large Hadron Collider is likely to resolve the mystery of parity violation in weak interaction, observation of neutrinoless double beta decay (0 ???) is expected to determine whether neutrinos are Majorana fermions. In this work we consider a class of LR models with TeV scale W R , Z R bosons but having parity restoration at high scales where they originate from well known Pati-Salam symmetry or SO(10) grand unified theory minimally extended to accommodate inverse seesaw frame work for neutrino masses. Most dominant new contribution to neutrinoless double beta decay is noted to occur via mediation involving lighter sterile neutrino exchanges. The next dominant contribution is found to be through mediation involving both light and heavy right-handed neutrino or sterile neutrino exchanges. The quark-lepton symmetric origin of the computed value of the Dirac neutrino mass matrix is also found to play a crucial role in determining these and other results on lepton flavor violating branching ratios for ? ? e + ?, ? ? ? + ?, and ? ? e + ? accessible to ongoing search experiments. The underlying non-unitarity matrix is found to manifest in substantial CP-violating effects even when the leptonic Dirac phase ?CP ? 0 ,? ,2?. Finally we explore a possible origin of the model in non-supersymmetric SO(10) grand unified theory where, in addition to low mass and Z R bosons accessible to Large Hadron Collider, the model is found to predict observable neutron-antineutron oscillation and lepto-quark gauge boson(mediated rare kaon decay with ? 10-9 - 10-11).

Awasthi, Ram Lal; Parida, M. K.; Patra, Sudhanwa

2013-08-01

175

Geometry and Cloaking Devices  

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

176

Geometry in Action  

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

177

The Common Geometry Module (CGM)  

Microsoft Academic Search

The Common Geometry Module (CGM) is a code library which provides geometry functionality used for mesh generation and other applications. This functionality includes that commonly found in solid modeling engines, like geometry creation, query and modification; CGM also includes capabilities not commonly found in solid modeling engines, like geometry decomposition tools and support for shared material interfaces. CGM is built

Tautges; Timothy James

2004-01-01

178

Watermarking MPEG-4 2D Mesh Animation in Multiresolution Analysis  

E-print Network

, and Chin-Yun Hsieh Department of Computer Science and Information Engineering National Taipei University of graphics anima- tion. In particular, the MPEG-4 dynamic 2D mesh that provides efficient cod- ing

Yang, Shih-Hsuan

179

Vortex unbinding in 2D classical JJ arrays  

SciTech Connect

Vortices for 2D superfluids are introduced and are described in terms of a 2D Coulomb gas. The 2D classical JJ array is modeled by a 2D XY-model and a mapping between the XY-model and the Coulomb gas is given. The physical properties of a JJ array are then given in terms of the corresponding Coulomb gas properties. First aspects of the Kosterlitz-Thouless vortex unbinding transitions are reviewed. Consequences for the resistance as well as the frequency dependent conductivity are described. Next the vortex unbinding induced by an external current is considered with Consequencies for the non-linear IV-characteristics. Finally some some effects of a perpendicular magnetic field are discussed in terms of an interplay between free vortices and bound vortex pairs.

Minnhagen, Petter [Dept. of Theor. Physics, Umea University, 901 87 Umea (Sweden)

1998-05-15

180

Constrained 3D navigation with 2D controllers  

Microsoft Academic Search

Navigation through 3D spaces is required in many interactive graphics and virtual reality applications. We consider the subclass of situations in which a 2D device such as a mouse controls smooth movements among viewpoints for a \\

Andrew J. Hanson; Eric A. Wernert

1997-01-01

181

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

182

A 2d spray model with gyroscopic effects. Ayman Moussa  

E-print Network

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

183

Geometry in 3-D  

NSDL National Science Digital Library

This resource guide from the Middle School Portal 2 project, written specifically for teachers, provides links to exemplary resources including background information, lessons, career information, and related national science education standards. The online resources featured in Geometry in 3-D actively engage students in exploring a variety of geometric shapes, at times through lessons that involve building models or creating paper nets that fold into three-dimensional shapes; at other times, through technology that allows students to rotate and zoom in on figures, noting their attributes and complexity. Other lessons offer problems on surface area and volume, a part of every middle school curriculum. The problems, each with a different twist on the subject, challenge students to reconsider their understanding of how to measure solids. Activities for developing spatial sense, another primary objective in teaching geometry, are also featured. Finally, there are online galleries of geometric solids, included for the rare opportunity they offer to show your students the beauty in mathematics. In Background Information, you will find workshop sessions developed for teachers and other materials that may interest you as a professional. Each resource deals specifically with three-dimensional geometry topics that align with the geometry and measurement standards recommended by NCTM.

Herrera, Terese

2006-09-01

184

Arithmetic, Geometry Calculus III  

E-print Network

students. Calculus III goes by various names: Vector Calculus, Multivariable Calculus, CalculusArithmetic, Geometry and Calculus III by W. Stephen Wilson Department of Mathematics Johns to approach the problem. In both the fall of 2007 and the fall of 2008, I taught Calculus III to over 200

Wilson, W. Stephen

185

Making Solid Geometry Solid.  

ERIC Educational Resources Information Center

Allowing students to use a polystyrene cutter to fashion their own three-dimensional models is suggested as a means of allowing individuals to experience problems and develop ideas related to solid geometry. A list of ideas that can lead to mathematical discovery is provided. (MP)

Hartz, Viggo

1981-01-01

186

The Helen of Geometry  

ERIC Educational Resources Information Center

The cycloid has been called the Helen of Geometry, not only because of its beautiful properties but also because of the quarrels it provoked between famous mathematicians of the 17th century. This article surveys the history of the cycloid and its importance in the development of the calculus.

Martin, John

2010-01-01

187

Conics and Finite Geometries.  

ERIC Educational Resources Information Center

The results of investigations into finite geometries, prompted by questions raised in a course for secondary school mathematics teachers, are presented. The discussion of points, lines, and incidences led to consideration of graphs of second-degree equations in finite projective planes. (MNS)

Shilgalis, Thomas W.

1985-01-01

188

Geometry Scavenger Hunt  

NSDL National Science Digital Library

This activity allows learners to practice observation skills and to realize examples of geometric shapes are everywhere. This geometry scavenger hunt (PDF) contains a set of directions and a recording sheet to complete. Included also is a list of materials and extension ideas.

2010-01-01

189

Gallery of Interactive Geometry  

NSDL National Science Digital Library

This is a collection of interactive geometry tools and applications. It includes tools such as WebPisces, Build a Rainbow, Escher-like tilings, projective conics, Cyberview-X (an application for 3D object viewing), and numerical integration. Some of the applications also feature simulations.

2009-06-06

190

Fractal geometry of music.  

PubMed Central

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

Hs, K J; Hs, A J

1990-01-01

191

Nano Shapes: Tiny Geometry  

NSDL National Science Digital Library

Advances in nanotechnology are due in part to the unique structure and properties of carbon nanotubes and buckyballs. These unusual structures are being studied for their potential use as vehicles for drug delivery, to strengthen materials, and as miniature circuits. Through an examination of the geometry of nanoscale materials, students explore the possibilities of nanoscale technologies.

Taylor, Amy R.; Broadwell, Bethany P.; Jones, M. G.; Falvo, Michael R.

2007-01-01

192

Advanced geometries and regimes  

SciTech Connect

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, Universit di Bologna and INFN Sezione di Bologna, Via Irnerio, 46-I-40126 Bologna (Italy)] [Dipartimento di Fisica, Universit 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, Universit di Roma, La Sapienza, 00165 Roma (Italy)] [Dipartimento di Energetica ed INFM, Universit 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

193

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

194

Geometry and physics  

PubMed Central

We review the remarkably fruitful interactions between mathematics and quantum physics in the past decades, pointing out some general trends and highlighting several examples, such as the counting of curves in algebraic geometry, invariants of knots and four-dimensional topology. PMID:20123740

Atiyah, Michael; Dijkgraaf, Robbert; Hitchin, Nigel

2010-01-01

195

Geometry of affine distributions  

Microsoft Academic Search

Bilinear affine distributions are considered from the point of view of their geometry in the time-frequency plane. General construction rules are established for interference terms, with further interpretations in terms of localization properties and generalized means. In the case of frequency modulated signals, it is shown how the pointwise application of these rules can be refined by the study of

Patrick Flandrin; P. Goncalves

1994-01-01

196

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.

Ltd, Lighthouse L.

2013-10-14

197

Seven-degree-of-freedom, quantum scattering dynamics study of the H2D++H2 reaction  

NASA Astrophysics Data System (ADS)

A quantum scattering dynamics, time-dependent wavepacket propagation method is applied to study the reaction of H2D++H2-->H3++HD on the Xie-Braams-Bowman potential energy surface. The reduced-dimensional, seven-degree-of-freedom approach is employed in this calculation by fixing one Jacobi and one torsion angle related to H2D+ at the lowest saddle point geometry of D2d on the potential energy surface. Initial state selected reaction probabilities are presented for various initial rovibrational states. The ground state reaction probability shows no threshold for this reaction, in other words, this reaction can occur without an activation barrier. The vibrational excitation shows that the stretching motion of H+-HD only has a small effect on the reaction probability; the vibrational excitation of HD in H2D+ hinders the reactivity. By contrast, rotational excitation of H+-HD greatly enhances the reactivity with the reaction probability increased double or triple at high rotational states compared to the ground state. Reactive resonances, seen in all the initial state selected reaction probabilities, are also found in the integral cross section for the ground state of H2D+ and H2. The thermal rate coefficient is also calculated and is found to be in semiquantitative agreement with experiment; however, quantum scattering approaches including more degrees of freedom, especially including all the angles, are necessary to study this reaction in the future.

Wang, Dunyou; Xie, Zhen; Bowman, Joel M.

2010-02-01

198

2D polariton-solitons in semiconductor microcavities  

Microsoft Academic Search

The aim of this contribution is the theoretical analysis of 2D-localized states, or 2D polariton-solitons (PSs) in a semiconductor microcavity, operating in the strong coupling regime. The mean-field model for coherent excitons strongly coupled to the cavity photons. The lower branch of the dispersion relation of semiconductor microcavities, operating in the strong-coupling regime, contains portion with both positive and negative

O. A. Egorov; D. V. Skryabin; A. V. Yulin; F. Lederer

2009-01-01

199

Application of TELEMAC-2D in a narrow estuarine tributary  

NASA Astrophysics Data System (ADS)

The numerical model TELEMAC-2D is applied to a tributary of the Weser estuary, the Hunte. In this tributary a high percentage of the incoming tidal energy is dissipated in a system of narrow bends. An estimation for the amount of energy dissipation resulting from bottom friction and turbulent dispersion is presented, which indicates that the latter plays an important role in this system. Therefore the advection schemes offered in TELEMAC-2D are compared with respect to their numerical diffusion.

Malcherek, Andreas

2000-09-01

200

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

201

On global regularity of 2D generalized magnetohydrodynamic equations  

NASA Astrophysics Data System (ADS)

In this article we study the global regularity of 2D generalized magnetohydrodynamic equations (2D GMHD), in which the dissipation terms are -?(u and -?(b. We show that smooth solutions are global in the following three cases: ??1/2,??1; 0??<1/2, 2?+?>2; ??2, ?=0. We also show that in the inviscid case ?=0, if ?>1, then smooth solutions are global as long as the direction of the magnetic field remains smooth enough.

Tran, Chuong V.; Yu, Xinwei; Zhai, Zhichun

202

2D numerical modeling of SiGe structures  

Microsoft Academic Search

2D modeling of SiGe devices and circuits is reviewed. SiGe HBT and SiGe ECL circuits are studied as an example. Numerical simulation is performed with Heterojunction Device and Circuit Analysis Advanced Application Modules in general purpose 2D device simulator MEDICI. Calculated results demonstrate that MEDICI can be used for advanced simulation tasks, which cannot be performed by more specialized simulators.

S. Amon; B. Ferk; D. Vrtacnik; D. Resnik; D. Krizaj; S. Sokolic

1998-01-01

203

2D Jet Simulation Testing SUNY Stony Brook  

E-print Network

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

204

A simultaneous 2D/3D autostereo workstation  

NASA Astrophysics Data System (ADS)

We present a novel immersive workstation environment that scientists can use for 3D data exploration and as their everyday 2D computer monitor. Our implementation is based on an autostereoscopic dynamic parallax barrier 2D/3D display, interactive input devices, and a software infrastructure that allows client/server software modules to couple the workstation to scientists' visualization applications. This paper describes the hardware construction and calibration, software components, and a demonstration of our system in nanoscale materials science exploration.

Chau, Dennis; McGinnis, Bradley; Talandis, Jonas; Leigh, Jason; Peterka, Tom; Knoll, Aaron; Sumer, Aslihan; Papka, Michael; Jellinek, Julius

2012-03-01

205

Spin diffusion in 2D and 3D quantum solids  

Microsoft Academic Search

A moment method is used to compute the anisotropic spin diffusion constant in two-dimensional (2D) adsorbed and bulk (3D) quantum solids in which the spin motion is induced by an exchange Hamiltonian. Computations are carried out in 2D for the square and triangular lattices and in 3D for the hcp lattice. It is assumed that there are pair and three-particle

B. Cowan; W. J. Mullin; E. Nelson

1989-01-01

206

High resolution 2-D spectral analysis at low SNR  

Microsoft Academic Search

This paper presents a fully two-dimensional high-resolution spectral analysis technique. The method consists of extrapolating observed data beyond the observation window by means of 2-D least squares prediction filters. High-resolution spectral analysis is then obtained by a discrete Fourier transform of the extrapolated data. Previously, methods of obtaining a high-resolution spectrum analysis on 2-D data have applied 1-D high-resolution analyses

O. Frost

1980-01-01

207

Imaging and diffraction characterisation of 2D inorganic nanostructures  

NASA Astrophysics Data System (ADS)

2D nanomaterials are a novel class of materials, noted for their potential in a range of high impact applications, such as sensing catalysis, and composite reinforcement. However, their structural features have not yet been fully characterised. In this work we have shown that 2D nanostructures of hBN, MoS2, and WS2, prepared by liquid exfoliation, can stack in sequences different from the bulk stacking. In 2D hBN non-sequential stacking was observed. 2D MoS2 and WS2 appear to have stacking where Mo/W atoms are located on the top of each other which differs from naturally occurring 2H and 3R polytypes. The majority of the hBN and MoS2 2D nanostructures retain the stacking of their bulk counterparts, while in 2D WS2 non-bulk stacking dominates. The conclusions are based primarily on the atomically resolved ADF STEM images with supporting evidence from electron diffraction.

Shmeliov, A.; Shannon, M.; Wang, P.; E, H.; Nellist, P. D.; Nicolosi, V.

2012-07-01

208

Elastic Pekeris waveguide normal mode solution comparisons against laboratory data  

E-print Network

with the shear wave field by an (s). An axially symmetric cylindrical coordinate geometry is assumed, the z-coordinate positive downwards, with the waveguide boundaries assumed planar and parallel. A time-harmonic point source potentials, /(r, z) and w(r, z), by p1 ¼ q1x2 /1; p2 ¼ q2c2 2 2 D2; (1) D2 ¼ 1 r @ @r ðru2? þ @w2 @z ; u2

209

Genetic polymorphisms of cytochrome P450 2D6 (CYP2D6): clinical consequences, evolutionary aspects and functional diversity  

Microsoft Academic Search

CYP2D6 is of great importance for the metabolism of clinically used drugs and about 2025% of those are metabolised by this enzyme. In addition, the enzyme utilises hydroxytryptamines as endogenous substrates. The polymorphism of the enzyme results in poor, intermediate, efficient or ultrarapid metabolisers (UMs) of CYP2D6 drugs. It is plausible that the UM genotype, where more than one active

M Ingelman-Sundberg

2005-01-01

210

Cylindrical geometry hall thruster  

DOEpatents

An apparatus and method for thrusting plasma, utilizing a Hall thruster with a cylindrical geometry, wherein ions are accelerated in substantially the axial direction. The apparatus is suitable for operation at low power. It employs small size thruster components, including a ceramic channel, with the center pole piece of the conventional annular design thruster eliminated or greatly reduced. Efficient operation is accomplished through magnetic fields with a substantial radial component. The propellant gas is ionized at an optimal location in the thruster. A further improvement is accomplished by segmented electrodes, which produce localized voltage drops within the thruster at optimally prescribed locations. The apparatus differs from a conventional Hall thruster, which has an annular geometry, not well suited to scaling to small size, because the small size for an annular design has a great deal of surface area relative to the volume.

Raitses, Yevgeny (Princeton, NJ); Fisch, Nathaniel J. (Princeton, NJ)

2002-01-01

211

Multilevel geometry optimization  

SciTech Connect

Geometry optimization has been carried out for three test molecules using six multilevel electronic structure methods, in particular Gaussian-2, Gaussian-3, multicoefficient G2, multicoefficient G3, and two multicoefficient correlation methods based on correlation-consistent basis sets. In the Gaussian-2 and Gaussian-3 methods, various levels are added and subtracted with unit coefficients, whereas the multicoefficient Gaussian-x methods involve noninteger parameters as coefficients. The multilevel optimizations drop the average error in the geometry (averaged over the 18 cases) by a factor of about two when compared to the single most expensive component of a given multilevel calculation, and in all 18 cases the accuracy of the atomization energy for the three test molecules improves; with an average improvement of 16.7 kcal/mol. (c) 2000 American Institute of Physics.

Rodgers, Jocelyn M. [Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431 (United States)] [Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431 (United States); Fast, Patton L. [Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431 (United States)] [Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431 (United States); Truhlar, Donald G. [Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431 (United States)] [Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431 (United States)

2000-02-15

212

Spinorial Geometry and Supergravity  

E-print Network

In the main part of this thesis, we present the foundations and initial results of the Spinorial Geometry formalism for solving Killing spinor equations. This method can be used for any supergravity theory, although we largely focus on D=11 supergravity. The D=5 case is investigated in an appendix. The exposition provides a comprehensive introduction to the formalism, and contains background material on the complex spin representations which, it is hoped, will provide a useful bridge between the mathematical literature and our methods. Many solutions to the D=11 Killing spinor equations are presented, and the consequences for the spacetime geometry are explored in each case. Also in this thesis, we consider another class of supergravity solutions, namely heterotic string backgrounds with (2,0) world-sheet supersymmetry. We investigate the consequences of taking alpha-prime corrections into account in the field equations, in order to remain consistent with anomaly cancellation, while requiring that spacetime supersymmetry is preserved.

Joe Gillard

2006-08-19

213

Rnyi entropy and geometry  

NASA Astrophysics Data System (ADS)

Entanglement entropy in even-dimensional conformal field theories (CFTs) contains well-known universal terms arising from the conformal anomaly. Rnyi entropies are natural generalizations of the entanglement entropy that are much less understood. Above two spacetime dimensions, the universal terms in the Rnyi entropies are unknown for general entangling geometries. We conjecture a new structure in the dependence of the four-dimensional Rnyi 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 Rnyi entropies across cylindrical entangling surfaces to corresponding three-dimensional massive Rnyi entropies across circular entangling surfaces. Our numerical technique also allows us to directly probe other interesting aspects of three-dimensional Rnyi entropy, including the massless renormalized Rnyi entropy and calculable contributions to the perimeter law.

Lee, Jeongseog; McGough, Lauren; Safdi, Benjamin R.

2014-06-01

214

Dual doubled geometry  

NASA Astrophysics Data System (ADS)

We probe doubled geometry with dual fundamental branes, i.e. solitons. Restricting ourselves first to solitonic branes with more than two transverse directions we find that the doubled geometry requires an effective wrapping rule for the solitonic branes which is dual to the wrapping rule for fundamental branes. This dual wrapping rule can be understood by the presence of Kaluza-Klein monopoles. Extending our analysis to supersymmetric solitonic branes with less than or equal to two transverse directions we show that such solitons are precisely obtained by applying the same dual wrapping rule to these cases as well. This extended wrapping rule cannot be explained by the standard Kaluza-Klein monopole alone. Instead, it suggests the existence of a class of generalized Kaluza-Klein monopoles in ten-dimensional string theory.

Bergshoeff, Eric A.; Riccioni, Fabio

2011-08-01

215

State Sums and Geometry  

E-print Network

In this thesis I review the definition of topological quantum field theories through state sums on triangulated manifolds. I describe the construction of state sum invariants of 3-manifolds from a graphical calculus and show how to evaluate the invariants as boundary amplitudes. I review how to define such a graphical calculus through SU(2) representation theory. I then review various geometricity results for the representation theory of SU(2), Spin(4) and SL(2,C), and define coherent boundary manifolds for state sums based on these representations. I derive the asymptotic geometry of the SU(2) based Ponzano-Regge invariant in three dimensions, and the SU(2) based Ooguri models amplitude in four dimensions. As a corollary to the latter results I derive the asymptotic behaviour of various recently proposed spin foam models motivated from the Plebanski formulation of general relativity. Finally the asymptotic geometry of the SL(2,C) based model is derived.

Frank Hellmann

2011-02-08

216

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

217

NON COMMUTATIVE DIFFERENTIAL GEOMETRY  

Microsoft Academic Search

In commutative differential geometry the Frolicher-Nijenhuis bracket computes all kinds of curvatures and obstructions to integrability. In (1) the Frolicher- Nijenhuis bracket was developed for universal differential forms of non-commutative algebras, and several applications were given. In this paper this bracket and the Frolicher-Nijenhuis calculus will be developed for several kinds of differential graded algebras based on derivations, which were

Michel Dubois-Violette; Peter W. Michor

218

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 chemistryfrom 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

219

Transient 2D-IR spectroscopy of inorganic excited states.  

PubMed

Time-resolved infrared spectroscopy has been proven to be a powerful tool for investigating the structure, dynamics and reactivity of electronically-excited states of inorganic molecules. As applications drive the production of ever more complex molecules however, experimental tools that can deliver more detailed spectroscopic information, or separate multiple contributions to complex signals will become increasingly valuable. In this Perspective, the extension of ultrafast infrared spectroscopy of inorganic excited states to a second frequency dimension using transient 2D-IR spectroscopy (T-2D-IR) methods is discussed. Following a brief discussion of the experimental methodologies, examples will be given of applications of T-2D-IR ranging from studies of the spectroscopy, structure and dynamics of photochemical intermediates to new tools for correlating vibrational modes in ground and excited electronic states and the investigation of excited state solvation dynamics. Future directions for these experiments are also discussed. PMID:25025224

Hunt, N T

2014-11-12

220

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

221

A simulation study of reactive flow in 2-D involving dissolution and precipitation in sedimentary rocks  

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

222

All null supersymmetric backgrounds of N=2, D=4 gauged supergravity coupled to abelian vector multiplets  

E-print Network

The lightlike supersymmetric solutions of N=2, D=4 gauged supergravity coupled to an arbitrary number of abelian vector multiplets are classified using spinorial geometry techniques. The solutions fall into two classes, depending on whether the Killing spinor is constant or not. In both cases, we give explicit examples of supersymmetric backgrounds. Among these BPS solutions, which preserve one quarter of the supersymmetry, there are gravitational waves propagating on domain walls or on bubbles of nothing that asymptote to AdS_4. Furthermore, we obtain the additional constraints obeyed by half-supersymmetric vacua. These are divided into four categories, that include bubbles of nothing which are asymptotically AdS_4, pp-waves on domain walls, AdS_3 x R, and spacetimes conformal to AdS_3 times an interval.

Dietmar Klemm; Emanuele Zorzan

2009-02-24

223

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

224

CYP 2D6 Binding Affinity Predictions Using Multiple Ligand and Protein Conformations  

PubMed Central

Because of the large flexibility and malleability of Cytochrome P450 enzymes (CYPs), in silico prediction of CYP binding affinities to drugs and other xenobiotic compounds is a true challenge. In the current work, we use an iterative linear interaction energy (LIE) approach to compute CYP binding affinities from molecular dynamics (MD) simulation. In order to improve sampling of conformational space, we combine results from simulations starting with different relevant protein-ligand geometries. For calculated binding free energies of a set of thiourea compounds binding to the flexible CYP 2D6 isoform, improved correlation with experiment was obtained by combining results ofMDruns starting from distinct protein conformations and ligand-binding orientations. This accuracy was obtained from relatively short MD simulations, which makes our approach computationally attractive for automated calculations of ligand-binding affinities to flexible proteins such as CYPs. PMID:24351831

Peric-Hassler, Lovorka; Stjernschantz, Eva; Oostenbrink, Chris; Geerke, Daan P.

2013-01-01

225

The critical behaviour of Ising spins on 2D Regge lattices  

E-print Network

We performed a high statistics simulation of Ising spins coupled to 2D quantum gravity on toroidal geometries. The tori were triangulated using the Regge calculus approach and contained up to $512^2$ vertices. We used a constant area ensemble with an added $R^2$ interaction term, employing the $dl/l$ measure. We find clear evidence that the critical exponents of the Ising phase transition are consistent with the static critical exponents and do not depend on the coupling strength of the $R^2$ interaction term. We definitively can exclude for this type of model a behaviour as predicted by Boulatov and Kazakov [Phys. Lett. {\\bf B186}, 379 (1987)] for Ising spins coupled to dynamically triangulated surfaces.

C. Holm; W. Janke

1994-06-27

226

Phase Mixing of Alfv\\'en Waves Near a 2D Magnetic Null Point  

E-print Network

The propagation of linear Alfv\\'en wave pulses in an inhomogeneous plasma near a 2D coronal null point is investigated. When a uniform plasma density is considered, it is seen that an initially planar Alfv\\'en wavefront remains planar, despite the varying equilibrium Alfv\\'en speed, and that all the wave collects at the separatrices. Thus, in the non-ideal case, these Alfv\\'enic disturbances preferentially dissipate their energy at these locations. For a non-uniform equilibrium density, it is found that the Alfv\\'en wavefront is significantly distorted away from the initially planar geometry, inviting the possibility of dissipation due to phase mixing. Despite this however, we conclude that for the Alfv\\'en wave, current density accumulation and preferential heating still primarily occur at the separatrices, even when an extremely non-uniform density profile is considered.

McLaughlin, J A

2014-01-01

227

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

NASA Technical Reports Server (NTRS)

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 preparation, domain decomposition, block boundary discretization. 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.

2002-01-01

228

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

229

A novel improved method for analysis of 2D diffusion relaxation data2D PARAFAC-Laplace decomposition  

NASA Astrophysics Data System (ADS)

This paper demonstrates how the multi-linear PARAFAC model can with advantage be used to decompose 2D diffusion-relaxation correlation NMR spectra prior to 2D-Laplace inversion to the T2- D domain. The decomposition is advantageous for better interpretation of the complex correlation maps as well as for the quantification of extracted T2- D components. To demonstrate the new method seventeen mixtures of wheat flour, starch, gluten, oil and water were prepared and measured with a 300 MHz nuclear magnetic resonance (NMR) spectrometer using a pulsed gradient stimulated echo (PGSTE) pulse sequence followed by a Carr-Purcell-Meiboom-Gill (CPMG) pulse echo train. By varying the gradient strength, 2D diffusion-relaxation data were recorded for each sample. From these double exponentially decaying relaxation data the PARAFAC algorithm extracted two unique diffusion-relaxation components, explaining 99.8% of the variation in the data set. These two components were subsequently transformed to the T2- D domain using 2D-inverse Laplace transformation and quantitatively assigned to the oil and water components of the samples. The oil component was one distinct distribution with peak intensity at D = 3 10 -12 m 2 s -1 and T2 = 180 ms. The water component consisted of two broad populations of water molecules with diffusion coefficients and relaxation times centered around correlation pairs: D = 10 -9 m 2 s -1, T2 = 10 ms and D = 3 10 -13 m 2 s -1, T2 = 13 ms. Small spurious peaks observed in the inverse Laplace transformation of original complex data were effectively filtered by the PARAFAC decomposition and thus considered artefacts from the complex Laplace transformation. The oil-to-water ratio determined by PARAFAC followed by 2D-Laplace inversion was perfectly correlated with known oil-to-water ratio of the samples. The new method of using PARAFAC prior to the 2D-Laplace inversion proved to have superior potential in analysis of diffusion-relaxation spectra, as it improves not only the interpretation, but also the quantification.

Tnning, Erik; Polders, Daniel; Callaghan, Paul T.; Engelsen, Sren B.

2007-09-01

230

Heterogeneous and Anisotropic Dynamics of a 2D Gel  

NASA Astrophysics Data System (ADS)

We report x-ray photon correlation spectroscopy (XPCS) results on bidimensional (2D) gels formed by a Langmuir monolayer of gold nanoparticles. The system allows an experimental determination of the fourth order time correlation function, which is compared to the usual second order correlation function and to the mechanical response measured on macroscopic scale. The observed dynamics is anisotropic, heterogeneous and superdiffusive on the nanoscale. Different time scales, associated with fast heterogeneous dynamics inside 2D cages and slower motion of larger parts of the film, can be identified from the correlation functions. The XPCS results are discussed in view of other experimental results and models of three-dimensional gel dynamics.

Orsi, D.; Cristofolini, L.; Baldi, G.; Madsen, A.

2012-03-01

231

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

PubMed

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

232

Matter in Toy Dynamical Geometries  

E-print Network

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

233

Geometry in Cryptography Luca Giuzzi  

E-print Network

Geometry in Cryptography Luca Giuzzi Summer School Giuseppe Tallini 9 July 2004 #12;Cryptosystems decryption k K : k K such that m M :d(e(m, k), k ) = m. Luca Giuzzi -- Geometry in Cryptography 1 #12;Discrete Logarithm Problem · G = g group · m G Determine N such that m = g Luca Giuzzi -- Geometry

Giuzzi, Luca

234

Discrete Differential Geometry Misha Kazhdan  

E-print Network

: · Surface Evolution ­ Mean-curvature flow ­ Willmore flow #12;Why Discrete Differential Geometry? Differential Geometry: · Surface Evolution ­ Mean-curvature flow ­ Willmore flow · Dynamical Systems ­ Twisting -= -= -= = - ktgv ga k k -= -= ( ) tvvg kk -=- - /1 #12;Why Discrete Differential Geometry? Example (Conservation

Kazhdan, Michael

235

A 3D Freehand Ultrasound System for Multi-view Reconstructions from Sparse 2D Scanning Planes  

PubMed Central

Background A significant limitation of existing 3D ultrasound systems comes from the fact that the majority of them work with fixed acquisition geometries. As a result, the users have very limited control over the geometry of the 2D scanning planes. Methods We present a low-cost and flexible ultrasound imaging system that integrates several image processing components to allow for 3D reconstructions from limited numbers of 2D image planes and multiple acoustic views. Our approach is based on a 3D freehand ultrasound system that allows users to control the 2D acquisition imaging using conventional 2D probes. For reliable performance, we develop new methods for image segmentation and robust multi-view registration. We first present a new hybrid geometric level-set approach that provides reliable segmentation performance with relatively simple initializations and minimum edge leakage. Optimization of the segmentation model parameters and its effect on performance is carefully discussed. Second, using the segmented images, a new coarse to fine automatic multi-view registration method is introduced. The approach uses a 3D Hotelling transform to initialize an optimization search. Then, the fine scale feature-based registration is performed using a robust, non-linear least squares algorithm. The robustness of the multi-view registration system allows for accurate 3D reconstructions from sparse 2D image planes. Results Volume measurements from multi-view 3D reconstructions are found to be consistently and significantly more accurate than measurements from single view reconstructions. The volume error of multi-view reconstruction is measured to be less than 5% of the true volume. We show that volume reconstruction accuracy is a function of the total number of 2D image planes and the number of views for calibrated phantom. In clinical in-vivo cardiac experiments, we show that volume estimates of the left ventricle from multi-view reconstructions are found to be in better agreement with clinical measures than measures from single view reconstructions. Conclusions Multi-view 3D reconstruction from sparse 2D freehand B-mode images leads to more accurate volume quantification compared to single view systems. The flexibility and low-cost of the proposed system allow for fine control of the image acquisition planes for optimal 3D reconstructions from multiple views. PMID:21251284

2011-01-01

236

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

237

What shape are dolphins? Building 3D morphable models from 2D images.  

PubMed

3D morphable models are low-dimensional parameterizations of 3D object classes which provide a powerful means of associating 3D geometry to 2D images. However, morphable models are currently generated from 3D scans, so for general object classes such as animals they are economically and practically infeasible. We show that, given a small amount of user interaction (little more than that required to build a conventional morphable model), there is enough information in a collection of 2D pictures of certain object classes to generate a full 3D morphable model, even in the absence of surface texture. The key restriction is that the object class should not be strongly articulated, and that a very rough rigid model should be provided as an initial estimate of the mean shape. The model representation is a linear combination of subdivision surfaces, which we fit to image silhouettes and any identifiable key points using a novel combined continuous-discrete optimization strategy. Results are demonstrated on several natural object classes, and show that models of rather high quality can be obtained from this limited information. PMID:22392707

Cashman, Thomas J; Fitzgibbon, Andrew W

2013-01-01

238

Lasing of pyrromethene 597 in 2D holographic polymer dispersed liquid crystals: influence of columnar conformation  

NASA Astrophysics Data System (ADS)

Holographic photopolymerization, such as used to form holographic polymer dispersed liquid crystals (HPDLCs), has the advantage of combining the desirable processing properties of polymers with a periodic distribution of an electrically tunable medium (LC). Herein we describe laser oscillations resulting from distributed feedback in fieldmodulated, 2-D H-PDLC photonic crystals. Compared to results of lasing from pyrromethene 597 in 1-D H-PDLCs, the linewidth of the laser action decreases by at least a factor of four and the lasing wavelength is electrically tunable over 5 nm. The 2-D H-PDLCs consist of LC columns within a polymer matrix that were created by interference of four writing beams on the sample cell. Two configurations were studied; one comprising a reflection grating orthogonal to a transmission grating (in-plane) and the other from two orthogonal transmission gratings (out-of-plane). Given that the lattice spacing was the same for both samples, the lasing wavelengths were similar; however the polarization dependence on lasing threshold varied by a factor of three for the in-plane configuration and electrical switching resulted in bimodal lasing. The out-of-plane geometry showed no polarization dependence on lasing threshold and the lasing blue-shifted with applied electric field.

Jakubiak, Rachel; Tondiglia, Vincent P.; Natarajan, Lalgudi V.; Lloyd, Pamela F.; Sutherland, Richard; Vaia, Richard A.; Bunning, Timothy J.

2009-02-01

239

Efficient implementation of the rank correlation merit function for 2D/3D registration.  

PubMed

A growing number of clinical applications using 2D/3D registration have been presented recently. Usually, a digitally reconstructed radiograph is compared iteratively to an x-ray image of the known projection geometry until a match is achieved, thus providing six degrees of freedom of rigid motion which can be used for patient setup in image-guided radiation therapy or computer-assisted interventions. Recently, stochastic rank correlation, a merit function based on Spearman's rank correlation coefficient, was presented as a merit function especially suitable for 2D/3D registration. The advantage of this measure is its robustness against variations in image histogram content and its wide convergence range. The considerable computational expense of computing an ordered rank list is avoided here by comparing randomly chosen subsets of the DRR and reference x-ray. In this work, we show that it is possible to omit the sorting step and to compute the rank correlation coefficient of the full image content as fast as conventional merit functions. Our evaluation of a well-calibrated cadaver phantom also confirms that rank correlation-type merit functions give the most accurate results if large differences in the histogram content for the DRR and the x-ray image are present. PMID:20844334

Figl, M; Bloch, C; Gendrin, C; Weber, C; Pawiro, S A; Hummel, J; Markelj, P; Pernus, F; Bergmann, H; Birkfellner, W

2010-10-01

240

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

PubMed

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

241

2D/3D registration with the CMA-ES method  

NASA Astrophysics Data System (ADS)

In this paper, we propose a new method for 2D/3D registration and report its experimental results. The method employs the Covariance Matrix Adaptation Evolution Strategy (CMA-ES) algorithm to search for an optimal transformation that aligns the 2D and 3D data. The similarity calculation is based on Digitally Reconstructed Radiographs (DRRs), which are dynamically generated from the 3D data using a hardware-accelerated technique - Adaptive Slice Geometry Texture Mapping (ASGTM). Three bone phantoms of different sizes and shapes were used to test our method: a long femur, a large pelvis, and a small scaphoid. A collection of experiments were performed to register CT to fluoroscope and DRRs of these phantoms using the proposed method and two prior work, i.e. our previously proposed Unscented Kalman Filter (UKF) based method and a commonly used simplex-based method. The experimental results showed that: 1) with slightly more computation overhead, the proposed method was significantly more robust to local minima than the simplex-based method; 2) while as robust as the UKF-based method in terms of capture range, the new method was not sensitive to the initial values of its exposed control parameters, and has also no special requirement about the cost function; 3) the proposed method was fast and consistently achieved the best accuracies in all compared methods.

Gong, Ren Hui; Abolmaesumi, Purang

2008-03-01

242

hal-00137965,version1-25Mar2007 A distributional approach to the geometry of 2D  

E-print Network

of dislocations in single crystals cannot be captured. In fact, dislocations are lines that either form loops, Louvain-la-Neuve, Belgium Keywords: dislocations, single crystals, multi-scale analysis, homogenisation crystals at the meso- scopic scale by considering concentrated effects, governed by the distribu- tion

Boyer, Edmond

243

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

244

SmaggIce 2D Version 1.8: Software Toolkit Developed for Aerodynamic Simulation Over Iced Airfoils  

NASA Technical Reports Server (NTRS)

SmaggIce 2D version 1.8 is a software toolkit developed at the NASA Glenn Research Center that consists of tools for modeling the geometry of and generating the grids for clean and iced airfoils. Plans call for the completed SmaggIce 2D version 2.0 to streamline the entire aerodynamic simulation process--the characterization and modeling of ice shapes, grid generation, and flow simulation--and to be closely coupled with the public-domain application flow solver, WIND. Grid generated using version 1.8, however, can be used by other flow solvers. SmaggIce 2D will help researchers and engineers study the effects of ice accretion on airfoil performance, which is difficult to do with existing software tools because of complex ice shapes. Using SmaggIce 2D, when fully developed, to simulate flow over an iced airfoil will help to reduce the cost of performing flight and wind-tunnel tests for certifying aircraft in natural and simulated icing conditions.

Choo, Yung K.; Vickerman, Mary B.

2005-01-01

245

Generation of a spatially coherent field structure in free-electron masers with 2D distributed feedback  

NASA Astrophysics Data System (ADS)

Nonlinear dynamics of free-electron masers (FEMs) is studied in the planar geometry with 2D distributed feedback (DFB). As is distinct from previous works, the field structure is not fixed with respect to the three spatial coordinates including the coordinate that is orthogonal to surfaces of the plates of the 2D Bragg resonator. Conditions on the allowed oversize parameter (ratio of the gap between the resonator plates to wavelength) under which the steady-state generation remains stable upon variation in electron-beam parameters are derived. It is demonstrated that, at a relatively large gap, variations in the mismatch lead to the jumps of oscillation frequency that correspond to the excitation of bunches of modes with different transverse indices of partial waves. The results of simulation using a particle-in-cell method are presented for a FEM prototype with 2D DFB that is created using an ELMI accelerator at the Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences. The simulated results show that narrow-band spatially coherent radiation can be generated at experimental parameters of the electron beam and electrodynamic system. The advantages of 2D Bragg structures in comparison with conventional 1D structures are demonstrated for FEMs.

Ginzburg, N. S.; Zaslavskii, V. Yu.; Malkin, A. M.; Sergeev, A. S.; Peskov, N. Yu.

2014-02-01

246

Probabilistic methods applied to 2D electromagnetic numerical dosimetry  

E-print Network

Probabilistic methods applied to 2D electromagnetic numerical dosimetry D. Voyer F. Musy L. Nicolas dosimetry problems in order to take into account the variability of the input parameters. Methodology Numerical dosimetry, electromagnetism, stochastic method, poly- nomial chaos, sparse grid. Paper type

Paris-Sud XI, Université de

247

Spatial Solitons in Quadratic 2D Nonlinear Photonic Crystals  

Microsoft Academic Search

We report on the first investigations into parametric solitary-wave formation in 2D nonlinear photonic crystals and present experimental results obtained in an hexagonally poled LiNbO3 waveguide designed for twin-beam second harmonic generation at telecom wavelengths.

Katia Gallo; Alessia Pasquazi; Salvatore Stivala; Gaetano Assanto

2007-01-01

248

2-D Imaging of Electron Temperature in Tokamak Plasmas  

SciTech Connect

By taking advantage of recent developments in millimeter wave imaging technology, an Electron Cyclotron Emission Imaging (ECEI) instrument, capable of simultaneously measuring 128 channels of localized electron temperature over a 2-D map in the poloidal plane, has been developed for the TEXTOR tokamak. Data from the new instrument, detailing the MHD activity associated with a sawtooth crash, is presented.

T. Munsat; E. Mazzucato; H. Park; C.W. Domier; M. Johnson; N.C. Luhmann Jr.; J. Wang; Z. Xia; I.G.J. Classen; A.J.H. Donne; M.J. van de Pol

2004-07-08

249

Vortex Crystals from 2D Euler Flow: Experiment and Simulation  

E-print Network

Chapter 4 Vortex Crystals from 2D Euler Flow: Experiment and Simulation 4.1 Introduction in a lower vorticity 123 #12; 124 3 ­1 vorticity (10 sec ) 3 300 30 Figure 4.1: Vortex crystals observed in magnetized electron columns [9]. The color map is logarithmic. This figure shows vortex crystals with (from

California at San Diego, University of

250

Wall-crossing in coupled 2d-4d systems  

NASA Astrophysics Data System (ADS)

We introduce a new wall-crossing formula which combines and generalizes the Cecotti-Vafa and Kontsevich-Soibelman formulas for supersymmetric 2d and 4d systems respectively. This 2d-4d wall-crossing formula governs the wall-crossing of BPS states in an {N}=2 supersymmetric 4d gauge theory coupled to a supersymmetric surface defect. When the theory and defect are compactified on a circle, we get a 3d theory with a supersymmetric line operator, corresponding to a hyperholomorphic connection on a vector bundle over a hyperkhler space. The 2d-4d wall-crossing formula can be interpreted as a smoothness condition for this hyperholomorphic connection. We explain how the 2d-4d BPS spectrum can be determined for 4d theories of class {S} , that is, for those theories obtained by compactifying the six-dimensional (0, 2) theory with a partial topological twist on a punctured Riemann surface C. For such theories there are canonical surface defects. We illustrate with several examples in the case of A 1 theories of class {S} . Finally, we indicate how our results can be used to produce solutions to the A 1 Hitchin equations on the Riemann surface C.

Gaiotto, Davide; Moore, Gregory W.; Neitzke, Andrew

2012-12-01

251

2D TwoPhase Jet Simulations SUNY Stony Brook  

E-print Network

Jet Into Still Air ­ VOF (Volume Of Fluid Method, FLUENT code) ­ CLSVOF (Coupled Level Set Volume #12;Outline · 2D Turbulent Jet Into Still Air ­ VOF (Volume Of Fluid Method, FLUENT code) ­ CLSVOF the movie] VOF CLSVOF 5 #12;Volume Fraction Of Water (Mercury Air ) [click to watch the movie] VOF

McDonald, Kirk

252

2-D airfoil tests including side wall boundary layer measurements  

Microsoft Academic Search

The data presented in this contribution were obtained in the DLR Transonic Wind Tunnel Braunschweig. The intent of the experiment was to provide data giving information on the development of the TWB-side wall boundary layer in the presence of a typical transonic airfoil model for further investigation of the influence of the side wall boundary layer on 2-D airfoil measurements.

W. Bartelheimer; K. H. Horstmann; W. Puffert-Meissner

1994-01-01

253

Stable Topological Skyrmions on the 2D Lattice  

E-print Network

In the continuum O(3) sigma model in two spatial dimensions, there are topological solitons whose size can be stabilized by adding Skyrme and potential terms. This paper describes a lattice version, namely a natural way of modifying the 2d Heisenberg model to achieve topological stability on the lattice.

R. S. Ward

1995-02-07

254

Nuclear Regulatory Legislation, 109th Congress, 2d Session.  

National Technical Information Service (NTIS)

This compilation of statutes and materials pertaining to nuclear regulatory legislation through the 109th Congress, 2d Session, has been prepared by the Office of the General Counsel, U.S. Nuclear Regulatory Commission, with the assistance of staff, for u...

2006-01-01

255

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

E-print Network

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

256

Projet PERSEE Schmas Perceptuels et Codage vido 2D  

E-print Network

comparable to conventional television. Therefore, it is of relevant im- portance to understand human vision of psychophysics 7 1.1 Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.2 Human perception-dimensional television (3DTV) is meant to enhance conventional 2D television by the added feeling of depth

Paris-Sud XI, Université de

257

2D ocean surface SAR images simulation: a statistical approach  

Microsoft Academic Search

This paper outlines a method for simulating the ocean surface as seen by a space borne synthetic aperture radar (SAR). A statistical approach was chosen in order to integrate the different mechanisms responsible for the imaging of the surface waves. A 2D sea-state surface was simulated, then divided in facets (of approximately the size of a resolution cell) and each

R. Garello; S. Proust; B. Chapron

1993-01-01

258

Evaluation of visual attention models under 2D similarity transformations  

Microsoft Academic Search

The computational models of visual attention, originally proposed as cognitive models of human attention, nowadays are being used as front-ends to some robotic vision systems, like automatic object recognition and landmark detection. However, these kinds of applications have different requirements from those originally proposed. More specifically, a robotic vision system must be relatively insensitive to 2D similarity transformations of the

Milton Roberto Heinen; Paulo Martins Engel

2009-01-01

259

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

260

A potential based panel method for 2-D hydrofoils  

Microsoft Academic Search

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

261

2D Static Light Scattering for Dairy Based Applications  

E-print Network

2D Static Light Scattering for Dairy Based Applications Jacob Lercke Skytte Kongens Lyngby 2014 Ph an exploratory study in relation to dairy based applications, with a major emphasis on the microstructure. The presented was financed by the Centre for Imaging Food Quality project, which is funded by the Danish Council

262

Realistic Picture of 2D Harmonic Oscillator Coherent States  

E-print Network

We show that a 2D harmonic oscillator coherent state is a soliton which has the same evolution as a spinning top: the center of mass follows a classical trajectory and the particle rotates around its center of mass in the same direction as its spin with the harmonic oscillator frequency.

Michel Gondran

2005-11-30

263

Sensing Facial Emotions in a Continuous 2D Affective Space  

E-print Network

expressive manner humans display emotions is through facial expressions. Facial expression is the mostSensing Facial Emotions in a Continuous 2D Affective Space Isabelle Hupont Reference Centre for emotional sensing and it constitutes an indispensable part of affective Human Computer Interface designs

Baldassarri, Sandra

264

2D Transformation Optics using Anisotropic Transmission-Line Metamaterials  

E-print Network

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.

265

Silver Staining of 2D Electrophoresis Gels Thierry Rabilloud  

E-print Network

Silver 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 are discussed in this chapter, and optimized silver staining protocols are proposed. ii. Key Words: mass

Paris-Sud XI, Université de

266

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

PubMed

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

267

Hidden Line Removal for 2D Cartoon Images  

Microsoft Academic Search

In this paper, we describe a hidden line removal scheme for 2D cartoon images. The depths are introduced to the polylines of the image. The surfaces of the image are classified and their depths updated according to the depths of polylines forming the surfaces. The hidden lines are identified b y comparing the depths of the polylines with the depths

Zhanggui Zeng; Hong Yan

2001-01-01

268

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

E-print Network

, 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.

269

Inviscid Limit for 2D Stochastic Navier-Stokes equations  

E-print Network

We consider stochastic Navier-Stokes equations in a 2D-bounded domain with the Navier with friction boundary condition. We establish the existence and the uniqueness of the solutions and study the vanishing viscosity limit. More precisely, we prove that solutions of stochastic Navier-Stokes equations converge, as the viscosity goes to zero, to solutions of the corresponding stochastic Euler equations.

Fernanda Cipriano; Ivn Torrecilla

2014-02-04

270

A 2D Game Using 3D Characters  

E-print Network

Two-dimensional graphics is used in the majority of current 2D games [Figure 1]. However, 3D virtual environments are more compelling. Previous research [1] found that females tend to choose easy and fun games rather than challenging games. While there are many serious games aimed at the educational function, these games need realistic graphics to attract users. Realistic

Na Chen; Ronald Mourant; Department Of Mechanical; Industrial Engineering

271

Motion-Synthesis Techniques for 2D Articulated Figures  

Microsoft Academic Search

In this paper we extend previous work on automatic motion syn- thesis for physically realistic 2D articulated figures in three ways. First, we describe an improved motion-synthesis algorithm that runs substantially faster than previously reported algorithms. Sec- ond, we present two new techniques for influencing the style of the motions generated by the algorithm. These techniques can be used by

Alex Fukunaga; Lloyd Hsu

272

Linearization of electrostatically actuated surface micromachined 2-D optical scanner  

Microsoft Academic Search

This paper presents an effective method of linearizing the electrostatic transfer characteristics of micromachined two-dimensional (2-D) scanners. The orthogonal scan angles of surface micromachined polysilicon scanner are controlled by using quadrant electrodes for electrostatic actuation. By using a pair of differential voltages over a bias voltage, we could improve the distortion of projected images from 72% to only 13%. A

Hiroshi Toshiyoshi; Wibool Piyawattanametha; Cheng-Ta Chan; Ming C. Wu

2001-01-01

273

Validation and testing of the VAM2D computer code  

SciTech Connect

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

274

Energy Dissipation Mechanisms in 2D Meteor Impacts  

Microsoft Academic Search

The morphology of meteor craters has historically been studied via static analysis, after the fact, of what are highly dynamic impact events. As such, there are long-standing questions about the means through which a meteor comes to rest and forms a crater. Using high speed video analysis on a 2D lab-scale system, we characterize the dynamics of a \\

Karen E. Daniels; Brian Utter; R. P. Behringer

2003-01-01

275

Rapid Reconstruction Method to 2D-Profiles Feature  

Microsoft Academic Search

The paper introduces a rapid and effective method to reconstruct 2D-profiles feature from data points. Firstly, the profiles point data are divided into lines points segments by incensement method, then fitting the points as lines saving lines parameters to line chain list; searching the line parameter chain list, if three are two continuous lines satisfy arc fitting conditions, computing the

Xiang-Juan Bian; You-Ping Gong

2009-01-01

276

Recursive Segmentation and Recognition Templates for 2D Parsing  

E-print Network

Recursive Segmentation and Recognition Templates for 2D Parsing Long (Leo) Zhu CSAIL MIT leozhu formulated in terms of parsing the input signal into a hierarchical representation. Natural language- time parsing algorithms. By contrast, the two-dimensional nature of images makes it much harder

Yuille, Alan L.

277

2D Mesoscale Simulations of Projectile Penetration into Sand  

Microsoft Academic Search

Physical Phenomena governing projectile instabilities during penetration of granular media (e.g. sand) are not well understood. To gain insight into projectile -- granular media interactions, 2-D mesoscale simulations were performed to examine projectile penetration into sand targets with explicit representation of sand grains and representative porosities. The computational procedure used to generate a mesoscale representation of a sand target is

R. D. Teeter; S. K. Dwivedi; C. W. Felice; Y. M. Gupta

2007-01-01

278

Graphene band structure and its 2D Raman mode  

NASA Astrophysics Data System (ADS)

High-precision simulations are used to generate the 2D Raman mode of graphene under a range of screening conditions and laser energies EL. We reproduce the decreasing trend of the 2D mode FWHM vs EL and the nearly linearly increasing dispersion ??2D/?EL seen experimentally in freestanding (unscreened) graphene, and propose relations between these experimentally accessible quantities and the local, two-dimensional gradients |? | of the electronic and TO phonon bands. In light of state-of-the-art electronic structure calculations that acutely treat the long-range e-e interactions of isolated graphene and its experimentally observed 2D Raman mode, our calculations determine a 40% greater slope of the TO phonons about K than given by explicit phonon measurements performed in graphite or GW phonon calculations in graphene. We also deduce the variation of the broadening energy ? [EL] for freestanding graphene and find a nominal value ? 140 meV, showing a gradually increasing trend for the range of frequencies available experimentally.

Narula, Rohit; Reich, Stephanie

2014-08-01

279

Application of collocation spectral domain decomposition method to solve radiative heat transfer in 2D partitioned domains  

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

280

The physics of 2D microfluidic droplet ensembles  

NASA Astrophysics Data System (ADS)

We review non-equilibrium many-body phenomena in ensembles of 2D microfluidic droplets. The system comprises of continuous two-phase flow with disc-shaped droplets driven in a channel, at low Reynolds number of 10-4-10-3. The basic physics is that of an effective potential flow, governed by the 2D Laplace equation, with multiple, static and dynamic, boundaries of the droplets and the walls. The motion of the droplets induces dipolar flow fields, which mediate 1/r2 hydrodynamic interaction between the droplets. Summation of these long-range 2D forces over droplet ensembles converges, in contrast to the divergence of the hydrodynamic forces in 3D. In analogy to electrostatics, the strong effect of boundaries on the equations of motion is calculated by means of image dipoles. We first consider the dynamics of droplets flowing in a 1D crystal, which exhibits unique phonon-like excitations, and a variety of nonlinear instabilities-all stemming from the hydrodynamic interactions. Narrowing the channel results in hydrodynamic screening of the dipolar interactions, which changes salient features of the phonon spectra. Shifting from a 1D ordered crystal to 2D disordered ensemble, the hydrodynamic interactions induce collective density waves and shocks, which are superposed on single-droplet randomized motion and dynamic clustering. These collective modes originate from density-velocity coupling, whose outcome is a 1D Burgers equation. The rich observational phenomenology and the tractable theory render 2D droplet ensembles a suitable table-top system for studying non-equilibrium many-body physics with long-range interactions.

Beatus, Tsevi; Bar-Ziv, Roy H.; Tlusty, Tsvi

2012-07-01

281

2D/3D Image Registration using Regression Learning  

PubMed Central

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 objects 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 regions 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 methods 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

282

Textile geometry preprocessor for meso-mechanical models of woven composites  

Microsoft Academic Search

A mathematical model of the internal geometry of 2D and 3D woven fabrics is used as a unit-cell geometry preprocessor for meso-mechanical models of composite materials. The model computes a spatial placement of all yarns in a fabric repeat for a given weave structure (a special coding algorithm is employed) and given warp and weft yarns geometrical and mechanical parameters.

S. V. Lomov; A. V. Gusakov; G. Huysmans; A. Prodromou; I. Verpoest

2000-01-01

283

Holographic Entanglement Entropy from 2d CFT: Heavy States and Local Quenches  

E-print Network

We consider the entanglement entropy in 2d conformal field theory in a class of excited states produced by the insertion of a heavy local operator. These include both high-energy eigenstates of the Hamiltonian and time-dependent local quenches. We compute the universal contribution from the stress tensor to the single interval Renyi entropies and entanglement entropy, and conjecture that this dominates the answer in theories with a large central charge and a sparse spectrum of low-dimension operators. The resulting entanglement entropies agree precisely with holographic calculations in three-dimensional gravity. High-energy eigenstates are dual to microstates of the BTZ black hole, so the corresponding holographic calculation is a geodesic length in the black hole geometry; agreement between these two answers demonstrates that entanglement entropy thermalizes in individual microstates of holographic CFTs. For local quenches, the dual geometry is a highly boosted black hole or conical defect. On the CFT side, the rise in entanglement entropy after a quench is directly related to the monodromy of a Virasoro conformal block.

Curtis T. Asplund; Alice Bernamonti; Federico Galli; Thomas Hartman

2014-10-06

284

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

ClinicalTrials.gov

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

2014-09-24

285

CSY3019 -Graphics Programming Assignment 1: Development of 2D/3D graphics software: Java 2D (50%)  

E-print Network

application is to include a Java 2D graphical representation of a disc rotor. A partial image of the disc% of the screen height. · AffineTransform used to translate, rotate, scale, shear, or perform a combination of the 'Additional functionality/complexity' above. Figure 2: Disc Rotor. #12;Technical Report The report should

Hill, Gary

286

Geometry of Periodic Monopoles  

E-print Network

BPS monopoles on $\\mathbb{R}^2\\times S^1$ correspond, via the generalized Nahm transform, to certain solutions of the Hitchin equations on the cylinder $\\mathbb{R}\\times S^1$. The moduli space M of two monopoles with their centre-of-mass fixed is a 4-dimensional manifold with a natural hyperk\\"ahler metric, and its geodesics correspond to slow-motion monopole scattering. The purpose of this paper is to study the geometry of M in terms of the Nahm/Hitchin data, i.e. in terms of structures on $\\mathbb{R}\\times S^1$. In particular, we identify the moduli, derive the asymptotic metric on M, and discuss several geodesic surfaces and geodesics on M. The latter include novel examples of monopole dynamics.

Rafael Maldonado; R S Ward

2013-09-26

287

Geometry from Gauge Theory  

SciTech Connect

We discuss how geometrical and topological aspects of certain (1/2)-BPS type IIB geometries are captured by their dual operators in N = 4 Super Yang-Mills theory. The type IIB solutions are characterized by arbitrary droplet pictures in a plane and we consider, in particular, axially symmetric droplets. The 1-loop anomalous dimension of the dual gauge theory operators probed with single traces is described by some bosonic lattice Hamiltonians. These Hamiltonians are shown to encode the topology of the droplets. In appropriate BMN limits, the Hamiltonians spectrum reproduces the spectrum of near-BPS string excitations propagating along each of the individual edges of the droplet. We also study semiclassical regimes for the Hamiltonians. For droplets having disconnected constituents, the Hamiltonian admits different complimentary semiclassical descriptions, each one replicating the semiclassical description for closed strings extending in each of the constituents.

Correa, Diego H. [DAMTP, Centre for Mathematical Sciences, University of Cambridge Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Silva, Guillermo A. [IFLP-CCT-La Plata, CONICET and Departamento de Fisica, Universidad Nacional de La Plata CC 67, (1900) La Plata (Argentina)

2008-07-28

288

Quantum, Gravity, and Geometry  

E-print Network

Recently, it is shown that, the quantum effects of matter are well described by the conformal degree of freedom of the space-time metric. On the other hand, it is a wellknown fact that according to Einstein's gravity theory, gravity and geometry are interconnected. In the new quantum gravity theory, matter quantum effects completely determine the conformal degree of freedom of the space-time metric, while the causal structure of the space-time is determined by the gravitational effects of the matter, as well as the quantum effects through back reaction effects. This idea, previousely, is realized in the framework of scalar-tensor theories. In this work, it is shown that quantum gravity theory can also be realized as a purely metric theory. Such a theory is developed, its consequences and its properties are investigated. The theory is applied, then, to black holes and the radiation-dominated universe. It is shown that the initial singularity can be avoided.

Ali Shojai

2000-10-04

289

Null twisted geometries  

E-print Network

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

2013-11-13

290

Titan 2D: Understanding Titans Seasonal Atmospheric Cycles  

NASA Astrophysics Data System (ADS)

In this study, we present results from a novel two-dimensional (2D) model that simulates the physics and chemistry of Titans atmosphere. Despite being an icy moon of Saturn, Titan is the only Solar System object aside from Earth that is sheathed by a thick nitrogen-dominated atmosphere. This vulnerable gaseous envelopean embodiment of a delicate coupling between photochemistry, radiation, and dynamicsis Natures laboratory for the synthesis of complex organic molecules. Titans large obliquity generates pronounced seasonal cycles in its atmosphere, and the Cassini spacecraft has been observing these variations since 2004. In particular, Cassini measurements show that the latitudinal distribution of Titans rich mlange of hydrocarbon species follows seasonal patterns. The mixing ratios of hydrocarbons increase with latitude towards the winter pole, suggesting a pole-to-pole circulation that reverses after equinox. Using a one-dimensional photochemical model of Titans atmosphere, we show that photochemistry alone cannot produce the observed meridional hydrocarbon distribution. This necessitates the employment of a 2D chemistry-transport model that includes meridional circulation as well as diffusive processes and photochemistry. Of additional concern, no previous 2D model of Titan extends beyond 500 km altitudea critical limitation since the peak of methane photolysis is at 800 km. Our 2D model is the first to include Titans stratosphere, mesosphere, and thermosphere. The meridional circulation in our 2D model is derived from the outputs of two general circulation models (GCMs): the TitanWRF GCM (Newman et al. 2011) covering the troposphere, stratosphere, and lower mesosphere, and a thermosphere general circulation model (TGCM) covering the remainder of the atmosphere through the thermosphere (Mller-Wodarg et al. 2003; 2008). This presentation will focus on the utilization of these advances applied to the 2D Caltech/JPL KINETICS model to understand the seasonal and meridional distribution of hydrocarbons as well as other atmospheric cycles on Titan.

Wong, Michael; Zhang, X.; Li, C.; Hu, R.; Shia, R.; Newman, C.; Mller-Wodarg, I.; Yung, Y.

2013-10-01

291

Gold-standard performance for 2D hydrodynamic modeling  

NASA Astrophysics Data System (ADS)

Two-dimensional, depth-averaged hydrodynamic (2D) models are emerging as an increasingly useful tool for environmental water resources engineering. One of the remaining technical hurdles to the wider adoption and acceptance of 2D modeling is the lack of standards for 2D model performance evaluation when the riverbed undulates, causing lateral flow divergence and convergence. The goal of this study was to establish a gold-standard that quantifies the upper limit of model performance for 2D models of undulating riverbeds when topography is perfectly known and surface roughness is well constrained. A review was conducted of published model performance metrics and the value ranges exhibited by models thus far for each one. Typically predicted velocity differs from observed by 20 to 30 % and the coefficient of determination between the two ranges from 0.5 to 0.8, though there tends to be a bias toward overpredicting low velocity and underpredicting high velocity. To establish a gold standard as to the best performance possible for a 2D model of an undulating bed, two straight, rectangular-walled flume experiments were done with no bed slope and only different bed undulations and water surface slopes. One flume tested model performance in the presence of a porous, homogenous gravel bed with a long flat section, then a linear slope down to a flat pool bottom, and then the same linear slope back up to the flat bed. The other flume had a PVC plastic solid bed with a long flat section followed by a sequence of five identical riffle-pool pairs in close proximity, so it tested model performance given frequent undulations. Detailed water surface elevation and velocity measurements were made for both flumes. Comparing predicted versus observed velocity magnitude for 3 discharges with the gravel-bed flume and 1 discharge for the PVC-bed flume, the coefficient of determination ranged from 0.952 to 0.987 and the slope for the regression line was 0.957 to 1.02. Unsigned velocity error had a median of 2.2 to 6.2 %. Several more model performance metrics, including spatial patterns, will be presented. These exceptional performance outcomes demonstrate that 2D models have relatively minor inherent performance limitations, so the key challenge for their use in practice is to obtain the most accurate topographic representation as possible.

Pasternack, G. B.; MacVicar, B. J.

2013-12-01

292

U N I N O V A W I S S E N S C H A F T S M A G A Z I N D E R U N I V E R S I TT B A S E L 1 11 M r z 2 0 0 9 die Evolution  

E-print Network

ä r z 2 0 0 9 Darwin und die Evolution #12;2 UNI NOVA 109/2008 Informatik U N I N O V A W I S S E N S I T? T B A S E L 1 0 6 ­ J u l i 2 0 0 7 Sport U N I N O V A W I S S E N S C H A F T S M A G A Z I N A S E L 1 0 7 ­ N o v . 2 0 0 7 #12;Editorial UNI NOVA 111/2009 3 Liebe Leserin, lieber Leser Es ist ein

Kölliker, Mathias

293

Ab? al-usayn al-Bar? and his Transmission of Biblical Materials from Kit?b al-D?n wa-al-Dawla by Ibn Rabban al-abar?: The Evidence from Fakhr al-D?n al-R?z?'s Maf?t? al-ghayb  

Microsoft Academic Search

The authenticity of the Kit?b al-d?n wa-al-dawla by the Nestorian convert to Islam, Ab? al-asan ?Al? b. Sahl Rabban al-abar? (d. ca. 251\\/865), has been discussed since the publication of the text by A. Mingana in 1922\\/23. A comparison between the chapter of the Twelver Sh??? Sad?d al-D?n Mam?d b. ?Al? al-imma? al-R?z?'s (d. after 600\\/1204) Munqidh min al-taql?d discussing

Sabine Schmidtke

2009-01-01

294

Comparison of aortic root dimensions and geometries before and after transcatheter aortic valve implantation by 2- and 3-dimensional transesophageal echocardiography and multislice computed tomography  

Microsoft Academic Search

BACKGROUND: 3D transesophageal echocardiography (TEE) may provide more accurate aortic annular and left ventricular outflow tract (LVOT) dimensions and geometries compared with 2D TEE. We assessed agreements between 2D and 3D TEE measurements with multislice computed tomography (MSCT) and changes in annular\\/LVOT areas and geometries after transcatheter aortic valve implantations (TAVI). METHODS AND RESULTS: Two-dimensional circular (pixr(2)), 3D circular, and

A. C. T. Ng; V. Delgado; F. van der Kley; M. Shanks; N. R. L. van de Veire; M. Bertini; G. Nucifora; R. J. van Bommel; L. F. Tops; A. de Weger; G. Tavilla; A. de Roos; L. J. Kroft; D. Y. Leung; J. Schuijf; M. J. Schalij; J. J. Bax

2010-01-01

295

Deformation of Quasi-2D Oil-in-Water Emulsions  

NASA Astrophysics Data System (ADS)

We create a quasi-2D nearly frictionless granular system, analogous to 2D granular systems of photoelastic disks but without static friction. To do this, we confine an oil-in-water emulsion between two glass plates such that the gap between the plates is smaller than the undeformed oil droplet diameter. For a range of droplet area fractions and plate separations, we observe the deformations the oil droplets experience due to contact with each other. The deformation of the droplet is correlated to the force its neighbors exert on it. As area fraction increases, the deformation of the droplets increases. By looking at the pattern of deformations throughout the system we visualize the location of force networks due to droplet-droplet interactions.

Golick, Laura; Desmond, Kenneth; Weeks, Eric R.

2010-03-01

296

Two-Particle Microrheology of quasi-2D Viscous Systems  

E-print Network

We study the correlated motions of colloidal particles in a quasi-2D system (Human Serum Albumin (HSA) protein molecules at an air-water interface) for different surface viscosities $\\eta_{s}$. We observe a transition in the behavior of the correlated motion, from 2-D interface dominated at high $\\eta_{s}$ to bulk fluid-dependent at low $\\eta_{s}$. The correlated motions can be scaled onto a master curve which captures the features of this transition. This master curve also characterizes the spatial dependence of the flow field of a viscous interface in response to a force. From the flow field and the correlated particle motions, we calculate a two-particle MSD (mean square displacement) for direct comparison with rheological measurements.

V. Prasad; S. A. Koehler; Eric R. Weeks

2006-04-11

297

A robust technique for 2D-3D registration.  

PubMed

A robust 2D-3D registration method with a wide capture range is presented. The method registers pre-operatively collected 3D computed tomography (CT) data sets of a single bone fragment to its intra-operative fluoroscope images. The registration technique relies on hardware rendering of CT data on consumer-grade graphics cards to generate digitally reconstructed radiographs (DRRs) in real time. We also employ unscented Kalman filter to solve for the non-linear dynamics governing this 2D-3D registration problem. The method is validated on phantom models of three different anatomies, namely scaphoid, pelvis and femur. We show that, under the same testing conditions, our proposed technique outperforms the conventional simplex-based method in capture range and robustness while providing comparable accuracy and computation time. PMID:17945644

Gong, Ren Hui; Abolmaesumi, Purang; Stewart, James

2006-01-01

298

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

299

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

300

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

301

Structural analysis of teicoplanin A2 by 2d NMR  

NASA Astrophysics Data System (ADS)

The analysis of the intact glycopeptide antibiotic, teicoplanin A 2, by two-dimensional proton NMR is described. Delayed-correlation spectroscopy (COSY), double-quantum coherence experiments (DACE), and nuclear Overhauser spectroscopy (NOESY) are utilized to confirm the primary structure. Distance constraints derived from NOESY data integrated with computer-assisted molecular modeling and force-field energy minimization yields a proposed three-dimensional solution-state conformation. Included are NMR methods developed for improved accuracy of distance measurements from 2D NOE experiments obtained on samples dissolved in DMSO- d6/water. The effects of different pulse sequences for water suppression on the 2D NOE spectral results are compared. Clear indication that teicoplanin exists in two unequally populated conformations which are in slow exchange is revealed by the presence of cross peaks attributable to conformational interchange in the NOESY spectra.

Heald, Sarah L.; Mueller, Luciano; Jeffs, Peter W.

302

2dF Spectroscopy of M104 Globular Clusters  

E-print Network

We present preliminary results of 2dF spectroscopy of globular clusters in The Sombrero (M104). We find 56 new clusters, and compile a total sample of 103 velocities combined with previous data. Our 2dF data extend out to 20 arcmin radius (~50 kpc), much further than previous studies. In the combined sample, we tentatively find a steep drop in the velocity dispersion with radius, which might possibly indicate a truncated halo. There is no obvious solid-body rotation over all radii, but separate fits for those clusters inside and outside 25 kpc radius show tantalizing evidence for counter-rotation. The projected mass estimator with isotropic orbits yields an M104 mass of 1.2x10^12 solar masses inside 50 kpc, and a (M/L)_B = 30: solid evidence for a dark matter halo in this galaxy.

Terry Bridges; Ken Freeman; Katherine Rhode; Steve Zepf

2002-11-18

303

In search of a 2-dB coding gain  

NASA Technical Reports Server (NTRS)

A recent code search found a (15,1/5), a (14,1/6), and a (15,1/6) convolutional code which, when concatenated with a 10-bit (1023,959) Reed-Solomon (RS) code, achieves a bit-error rate (BER) of 0.000001 at a bit signal-to-noise ratio (SNR) of 0.50 dB, 0.47 dB and 0.42 B, respectively. All of these three codes outperform the Voyager communication system, our baseline, which achieves a BER of 10.000001 at bit SNR of 2.53 db, by more than 2 dB. The 2 dB coding improvement goal was exceeded.

Yuen, J. H.; Vo, Q. D.

1985-01-01

304

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

305

A Better 2-D Mechanical Energy Conservation Experiment  

NASA Astrophysics Data System (ADS)

A variety of simple classical mechanics energy conservation experiments are used in teaching laboratories. Typical one-dimensional (1-D) setups may involve falling balls or oscillating springs. Many of these can be quite satisfying in that students can confirmwithin a few percentthat mechanical energy is conserved. Students generally have little trouble identifying discrepancies such as the loss of a few percent of the gravitational potential energy due to air friction encountered by a falling ball. Two-dimensional (2-D) systems can require more sophisticated analysis for higher level laboratories, but such systems often incorporate complicating components that can make the exercise academically incomplete and experimentally less accurate. The following describes a simple 2-D energy conservation experiment based on the popular "Newton's Cradle" toy that allows students to account for nearly all of the mechanical energy in the system in an academically complete analysis.

Paesler, Michael

2012-02-01

306

Human microRNA-1245 down-regulates the NKG2D receptor in natural killer cells and impairs NKG2D-mediated functions  

PubMed Central

Background NKG2D is an activating receptor expressed by natural killer and T cells, which have crucial functions in tumor and microbial immunosurveillance. Several cytokines have been identified as modulators of NKG2D receptor expression. However, little is known about NKG2D gene regulation. In this study, we found that microRNA 1245 attenuated the expression of NKG2D in natural killer cells. Design and Methods We investigated the potential interactions between the 3?-untranslated region of the NKG2D gene and microRNA as well as their functional roles in the regulation of NKG2D expression and cytotoxicity in natural killer cells. Results Transforming growth factor-?1, a major negative regulator of NKG2D expression, post-transcriptionally up-regulated mature microRNA-1245 expression, thus down-regulating NKG2D expression and impairing NKG2D-mediated immune responses in natural killer cells. Conversely, microRNA-1245 down-regulation significantly increased the expression of NKG2D expression in natural killer cells, resulting in more efficient NKG2D-mediated cytotoxicity. Conclusions These results reveal a novel NKG2D regulatory pathway mediated by microRNA-1245, which may represent one of the mechanisms used by transforming growth factor-?1 to attenuate NKG2D expression in natural killer cells. PMID:22491735

Espinoza, J. Luis; Takami, Akiyoshi; Yoshioka, Katsuji; Nakata, Katsuya; Sato, Tokiharu; Kasahara, Yoshihito; Nakao, Shinji

2012-01-01

307

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

308

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.

2005-11-03

309

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

310

Hand movement strategies in telecontrolled motion along 2-D trajectories  

Microsoft Academic Search

The authors evaluate the performance and try to identify the strategies of human operators (HOs) teleoperating a robot along 2-D-trajectories in simulations of place-like tasks in an obstacle encumbered environment. The experiments utilize computer graphic simulations of a remote robot whose end-effector displacements are dynamically controlled in the X-Y plane by the HO's hand displacements. The performance is described in

Giovanni Magenes; Jean Louis Vercher; Gabriel M. Gauthier

1992-01-01

311

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

312

Instantons in the Quantum Framework of 2D Gravity  

E-print Network

We analyze the non--perturbative features of 2D quantum gravity defined by stochastic regularization of the unstable matrix model showing, first, that the WKB approximation of the well-defined quantum Fokker-Planck hamiltonian corresponds to the semiclassical eigenvalue density of the former. The double scaled potential exhibits an instanton--like behaviour, which is universal and scales, but whose interpretation in terms of pure gravity is still open.

J. Luis Miramontes; Joaquin Sanchez Guillen

1991-10-18

313

Electronic and magnetic properties of 2D BCN nanostructures  

NASA Astrophysics Data System (ADS)

Recent developments of two-dimensional (2D) nanomaterials hold great promises for future electronics, optics and spintronics. Since the isolation and electronic characterization of graphene, other layered 2D crystals also have been synthesized. In particular, carbon can be combined with its neighboring atoms in the periodic table, boron and nitrogen as hexagonal BN (h-BN), to obtain hybrid BCN configurations. These BCN 2D nanostructures show a rich variety of physical properties, distinct from parent materials. Their electronic properties can in principle be tuned by varying the concentration of each of the three elements. We study electronic structures of a variety of 2D BCN nanostructures using hybrid functional HSE in density functional theory (DFT). We show that their electronic properties can be gradually tuned by composition and the atomic configuration of three elements. We demonstrate that the substitution-induced impurity states, associated with carbon atoms, and their interactions dictate the electronic structure and properties of C-doped h-BN. Stacking of localized impurity states in small C clusters embedded in h-BN forms a set of discrete energy levels in the wide gap of h-BN, leading to electronic structures of quantum dots made of carbon nano-domains for applications in optics and opto-electronics. We also show that half-metallic electron transport can be achieved by low concentration substitutional doping of only one sublattice of graphene by nitrogen or boron atoms. The delocalized spin-densities induced by the unpaired electrons at substitutional sites permeate only through the sublattice where the nitrogen (boron) atoms belong. For interacting nitrogen (boron) atoms located along the ``zigzag'' direction and in the same sublattice the ferro-magnetic spin-ordering is energetically favored, and substitution-induced impurity states selectively disturb the spin-polarized ?-orbital of that same sublattice.

Park, Hyoungki

2013-03-01

314

Report of the 1988 2-D Intercomparison Workshop, chapter 3  

NASA Technical Reports Server (NTRS)

Several factors contribute to the errors encountered. With the exception of the line-by-line model, all of the models employ simplifying assumptions that place fundamental limits on their accuracy and range of validity. For example, all 2-D modeling groups use the diffusivity factor approximation. This approximation produces little error in tropospheric H2O and CO2 cooling rates, but can produce significant errors in CO2 and O3 cooling rates at the stratopause. All models suffer from fundamental uncertainties in shapes and strengths of spectral lines. Thermal flux algorithms being used in 2-D tracer tranport models produce cooling rates that differ by as much as 40 percent for the same input model atmosphere. Disagreements of this magnitude are important since the thermal cooling rates must be subtracted from the almost-equal solar heating rates to derive the net radiative heating rates and the 2-D model diabatic circulation. For much of the annual cycle, the net radiative heating rates are comparable in magnitude to the cooling rate differences described. Many of the models underestimate the cooling rates in the middle and lower stratosphere. The consequences of these errors for the net heating rates and the diabatic circulation will depend on their meridional structure, which was not tested here. Other models underestimate the cooling near 1 mbar. Suchs errors pose potential problems for future interactive ozone assessment studies, since they could produce artificially-high temperatures and increased O3 destruction at these levels. These concerns suggest that a great deal of work is needed to improve the performance of thermal cooling rate algorithms used in the 2-D tracer transport models.

Jackman, Charles H.; Brasseur, Guy; Soloman, Susan; Guthrie, Paul D.; Garcia, Rolando; Yung, Yuk L.; Gray, Lesley J.; Tung, K. K.; Ko, Malcolm K. W.; Isaken, Ivar

1989-01-01

315

Solution structure of ?-conotoxin MVIIA using 2D NMR spectroscopy  

Microsoft Academic Search

The solution structure of ?-conotoxin MVIIA (SNX-111), a peptide toxin from the fish hunting cone snail Conus magus and a high-affinity blocker of N-type calcium channels, was determined by 2D NMR spectroscopy. The backbones of the best 44 structures match with an average pairwise RMSD of 0.59 angstroms. The structures contain a short segment of triple-stranded ?-sheet involving residues 68,

Vladimir J. Basus; Laszlo Nadasdi; J. Ramachandran; George P. Miljanich

1995-01-01

316

Local topological order inhibits thermal stability in 2D  

E-print Network

We study the robustness of quantum information stored in the degenerate ground space of a local, frustration-free Hamiltonian with commuting terms on a 2D spin lattice. On one hand, a macroscopic energy barrier separating the distinct ground states under local transformations would protect the information from thermal fluctuations. On the other hand, local topological order would shield the ground space from static perturbations. Here we demonstrate that local topological order implies a constant energy barrier, thus inhibiting thermal stability.

Olivier Landon-Cardinal; David Poulin

2012-09-25

317

3D structures by 2D vibrational spectroscopy  

PubMed Central

Conspectus The development of experiments that can generate molecular movies of changing chemical structures is a major challenge for physical chemistry. But to realize this dream, we not only need to significantly improve existing approaches, but we also must invent new technologies .. Most of the known protein structures have been determined by X-ray diffraction and to lesser extent by NMR. Though powerful, X-ray diffraction presents limitations for acquiring time dependent structures. In the case of NMR, ultrafast equilibrium dynamics might be inferred from lineshapes, but the structures of conformations interconverting on such time scales are not realizable. This Account highlights two dimensional infrared spectroscopy (2D IR), in particular the 2D vibrational echo, as an approach to time resolved structure determination. We outline the use of the 2D IR method to completely determine the structure of a protein of the integrin family in a time window of few picoseconds. As a transmembrane protein, this class of structures has proved particularly challenging for the established structural methodologies of x-ray crystallography and NMR. We describe the challenges facing multidimensional spectroscopy and compare it with some other methods of structural biology. Then we succinctly discuss the basic principles of 2D IR methods as they relate to time domain and frequency domain experimental and theoretical properties required for protein structure determination. By means of the example of the transmembrane protein, we describe the essential aspects of combined carbon-13 oxygen-18 isotope labels to create vibrational resonance pairs that allow the determination of protein and peptide structures in motion. Finally, we propose a three dimensional structure of the ?IIb transmembrane homodimer that includes optimum locations of all side chains and backbone atoms of the protein. Delocalization among 13C=18O residues on different helices. The vibrational excitation is transferred between modes on different helices on the coherent energy transfer time ?/2?. PMID:22458539

Remorino, Amanda; Hochstrasser, Robin M.

2012-01-01

318

Watermarking curves using 2D mesh spectral transform  

Microsoft Academic Search

This paper presents a robust watermarking method for curves that uses informed-detection. To embed watermarks, the presented algorithm parameterizes a curve using the B-spline model and acquires the control points of the B-spline model. For these control points, 2D mesh are created by applying Delaunay triangulation and then the mesh spectral analysis is performed to calculate the mesh spectral coefficients

Ji Young Kim; Im Dong-hyuck; Hae-yeoun Lee; Heung-kyu Lee

2008-01-01

319

Predicting 3D People from 2D Pictures  

Microsoft Academic Search

We propose a hierarchical process for inferring the 3D pose of a per- son from monocular images. First we infer a learned view-based 2D body model from a single image using non-parametric belief propagation. This approach integrates information from bottom-up body-part proposal processes and deals with self-occlusion to compute distributions over limb poses. Then, we exploit a learned Mixture of

Leonid Sigal; Michael J. Black

2006-01-01

320

On the effective shear speed in 2D phononic crystals  

E-print Network

The quasistatic limit of the antiplane shear-wave speed ('effective speed') $c$ in 2D periodic lattices is studied. Two new closed-form estimates of $c$ are derived by employing two different analytical approaches. The first proceeds from a standard background of the plane wave expansion (PWE). The second is a new approach, which resides in $\\mathbf{x}$-space and centers on the monodromy matrix (MM) introduced in the 2D case as the multiplicative integral, taken in one coordinate, of a matrix with components being the operators with respect to the other coordinate. On the numerical side, an efficient PWE-based scheme for computing $c$ is proposed and implemented. The analytical and numerical findings are applied to several examples of 2D square lattices with two and three high-contrast components, for which the new PWE and MM estimates are compared with the numerical data and with some known approximations. It is demonstrated that the PWE estimate is most efficient in the case of densely packed stiff inclusions, especially when they form a symmetric lattice, while in general it is the MM estimate that provides the best overall fitting accuracy.

A. A. Kutsenko; A. L. Shuvalov; A. N. Norris; O. Poncelet

2011-06-27

321

2D luminescence imaging of pH in vivo  

PubMed Central

Luminescence imaging of biological parameters is an emerging field in biomedical sciences. Tools to study 2D pH distribution are needed to gain new insights into complex disease processes, such as wound healing and tumor metabolism. In recent years, luminescence-based methods for pH measurement have been developed. However, for in vivo applications, especially for studies on humans, biocompatibility and reliability under varying conditions have to be ensured. Here, we present a referenced luminescent sensor for 2D high-resolution imaging of pH in vivo. The ratiometric sensing scheme is based on time-domain luminescence imaging of FITC and ruthenium(II)tris-(4,7-diphenyl-1,10-phenanthroline). To create a biocompatible 2D sensor, these dyes were bound to or incorporated into microparticles (aminocellulose and polyacrylonitrile), and particles were immobilized in polyurethane hydrogel on transparent foils. We show sensor precision and validity by conducting in vitro and in vivo experiments, and we show the versatility in imaging pH during physiological and chronic cutaneous wound healing in humans. Implementation of this technique may open vistas in wound healing, tumor biology, and other biomedical fields. PMID:21262842

Schreml, Stephan; Meier, Robert J.; Wolfbeis, Otto S.; Landthaler, Michael; Szeimies, Rolf-Markus; Babilas, Philipp

2011-01-01

322

General 2D phase correction method for interleaved EPI reconstruction  

NASA Astrophysics Data System (ADS)

Interleaved echo-planar imaging (EPI) and spiral imaging are two fast clinical magnetic resonance imaging (MRI) schemes that obtain k-space signal more efficiency for encoding an object. Since points along their k-space trajectories are from different echo times that may carry different phase and amplified errors originating from the static magnetic field inhomogeneity and nuclear spin relaxation, to form an image free of artifacts, both phase and amplitude errors need to be compensated properly in the image reconstruction. To address this issue, we have develop a general image reconstruction technique which is capable of accomplishing 2D phase correction for image reconstruction of interleaved EPI and spiral data. In this technique we formulated the image reconstructions as a problem of finding an optical solution to a set of linear algebraic equations corresponding to a specific imaging measurement. Furthermore, the phase errors, as well as other constraints known of the image, can be incorporated into these equations. The final solution can be obtained by solving the equation via an iterative procedure, free of k-space data gridding. Images with 2D phase correction have been successfully reconstructed using a set of imaging data acquired on a clinical MRI scanner. The significance of the work is that it has demonstrated that the 2D spatial phase correction can be accomplished for a set of interleaved EPI acquisition. Also, this is a flexible image reconstruction method for further improving the resulting image quality.

Liu, Haiying

1998-11-01

323

Wide-Field H2D+ Observations of Starless Cores  

NASA Astrophysics Data System (ADS)

In recent years, isolated starless cores have been revealed to have significant chemical differentiation with very low abundances of carbon-bearing molecules (such as CO and its isotopologues) in their cold, dense interiors. The inner regions of such cores, however, may be quite interesting, e.g., if contraction or collapse begins there. To explore these regions, we present detections of six isolated starless cores in the 110-111 line of H2D+ at 372 GHz using the new HARP instrument at the James Clerk Maxwell Telescope. Since the detection of this line requires very dry conditions on Mauna Kea (i.e., ?(225 GHz) < 0.05), only a multi-beam receiver system like the 4 X 4 HARP array can locate H2D+ emission across such cores in a practical amount of observing time. In all cases, the brightest line emission is coincident with the local peak of submillimeter continuum emission, but significant H2D+ emission is detected offset from the continuum peak in some. In addition, we describe the thermal and turbulent velocity fields in these cores revealed by these lines.

Di Francesco, James; Friesen, R.; Caselli, P.; Myers, P. C.; van der Tak, F. F. S.; Ceccarelli, C.

2009-01-01

324

Volumetric elasticity imaging with a 2-D CMUT array.  

PubMed

This article reports the use of a two-dimensional (2-D) capacitive micro-machined ultrasound transducer (CMUT) to acquire radio-frequency (RF) echo data from relatively large volumes of a simple ultrasound phantom to compare three-dimensional (3-D) elasticity imaging methods. Typical 2-D motion tracking for elasticity image formation was compared with three different methods of 3-D motion tracking, with sum-squared difference (SSD) used as the similarity measure. Differences among the algorithms were the degree to which they tracked elevational motion: not at all (2-D search), planar search, combination of multiple planes and plane independent guided search. The cross-correlation between the predeformation and motion-compensated postdeformation RF echo fields was used to quantify motion tracking accuracy. The lesion contrast-to-noise ratio was used to quantify image quality. Tracking accuracy and strain image quality generally improved with increased tracking sophistication. When used as input for a 3-D modulus reconstruction, high quality 3-D displacement estimates yielded accurate and low noise modulus reconstruction. PMID:20510188

Fisher, Ted G; Hall, Timothy J; Panda, Satchi; Richards, Michael S; Barbone, Paul E; Jiang, Jingfeng; Resnick, Jeff; Barnes, Steve

2010-06-01

325

Volumetric Elasticity Imaging with a 2D CMUT Array  

PubMed Central

This paper reports the use of a two-dimensional (2D) capacitive micro-machined ultrasound transducer (CMUT) to acquire radio frequency (RF) echo data from relatively large volumes of a simple ultrasound phantom to compare 3D elasticity imaging methods. Typical 2D motion tracking for elasticity image formation was compared to three different methods of 3D motion tracking, with sum-squared difference (SSD) used as the similarity measure. Differences among the algorithms were the degree to which they tracked elevational motion: not at all (2D search), planar search, combination of multiple planes, and plane independent guided search. The cross correlation between the pre-deformation and motion-compensated post-deformation RF echo fields was used to quantify motion tracking accuracy. The lesion contrast-to-noise ratio was used to quantify image quality. Tracking accuracy and strain image quality generally improved with increased tracking sophistication. When used as input for a 3D modulus reconstruction, high quality 3D displacement estimates yielded accurate and low noise modulus reconstruction. PMID:20510188

Fisher, Ted G.; Hall, Timothy J.; Panda, Satchi; Richards, Michael S.; Barbone, Paul E.; Jiang, Jingfeng; Resnick, Jeff; Barnes, Steve

2010-01-01

326

Planetary Image Geometry Library  

NASA Technical Reports Server (NTRS)

The Planetary Image Geometry (PIG) library is a multi-mission library used for projecting images (EDRs, or Experiment Data Records) and managing their geometry for in-situ missions. A collection of models describes cameras and their articulation, allowing application programs such as mosaickers, terrain generators, and pointing correction tools to be written in a multi-mission manner, without any knowledge of parameters specific to the supported missions. Camera model objects allow transformation of image coordinates to and from view vectors in XYZ space. Pointing models, specific to each mission, describe how to orient the camera models based on telemetry or other information. Surface models describe the surface in general terms. Coordinate system objects manage the various coordinate systems involved in most missions. File objects manage access to metadata (labels, including telemetry information) in the input EDRs and RDRs (Reduced Data Records). Label models manage metadata information in output files. Site objects keep track of different locations where the spacecraft might be at a given time. Radiometry models allow correction of radiometry for an image. Mission objects contain basic mission parameters. Pointing adjustment ("nav") files allow pointing to be corrected. The object-oriented structure (C++) makes it easy to subclass just the pieces of the library that are truly mission-specific. Typically, this involves just the pointing model and coordinate systems, and parts of the file model. Once the library was developed (initially for Mars Polar Lander, MPL), adding new missions ranged from two days to a few months, resulting in significant cost savings as compared to rewriting all the application programs for each mission. Currently supported missions include Mars Pathfinder (MPF), MPL, Mars Exploration Rover (MER), Phoenix, and Mars Science Lab (MSL). Applications based on this library create the majority of operational image RDRs for those missions. A Java wrapper around the library allows parts of it to be used from Java code (via a native JNI interface). Future conversions of all or part of the library to Java are contemplated.

Deen, Robert C.; Pariser, Oleg

2010-01-01

327

All supersymmetric solutions of N = 2, D = 4 gauged supergravity  

Microsoft Academic Search

We classify all supersymmetric solutions of minimal gauged supergravity in four dimensions. There are two classes of solutions that are distinguished by the norm of the Killing vector constructed from the Killing spinor. If the Killing vector is timelike, the solutions are determined by the geometry of a two-dimensional base-manifold. When it is lightlike, the most general BPS solution is

Marco M. Caldarelli; Dietmar Klemm

2003-01-01

328

Solution conformation of 2-aminopurine (2-AP) dinucleotide determined by ultraviolet 2D fluorescence spectroscopy (UV-2D FS)  

PubMed Central

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 0.5 , 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

329

Solving a 2D Knapsack Problem Using a Hybrid Data-Parallel/Control  

E-print Network

for solving a NP class, 2D knapsack (or cutting-stock) problem which is the optimal packing of multiples of n constraints. Such problems appear in computer science and operations research, e.g. in cutting stock ( 0 , 0 )( 0 , 0 ) Figure 1: A possible 2D cutting stock solution #12;2 The 2D knapsack problem The 2D

Potter, Jerry L.

330

Ultrafast 2D NMR Spectroscopy Using Sinusoidal Gradients: Principles and Ex Vivo Brain Investigations  

E-print Network

Ultrafast 2D NMR Spectroscopy Using Sinusoidal Gradients: Principles and Ex Vivo Brain ultrafast acquisitions of 2D NMR spectra with suitable spectral widths on a microimaging probe (for both Wiley-Liss, Inc. Key words: ultrafast 2D NMR; magnetic resonance spectros- copy; brain metabolites; 2D

Frydman, Lucio

331

Spatially encoded NMR and the acquisition of 2D magnetic resonance images within a single scan  

E-print Network

Spatially encoded NMR and the acquisition of 2D magnetic resonance images within a single scan Yoav out analytical characterizations on chemical and biochemical samples [2,3] 2D NMR probably finds its resonance imaging (MRI). In spite of the dissimilar information being sought in 2D NMR and 2D MRI

Frydman, Lucio

332

2D Observers in 3D Object Recognition NEC Research Institute  

E-print Network

functions GRBF, 2D closest template matching that allows 2D a ne transformations of in- dependent 2D, still remains an area of strong debate. Previously, we showed that all models that allow rotations in the image plane of independent 2D templates could not account for human performance in discriminating novel

Kersten, Dan

333

1D + 1D ? 1D polyrotaxane, 2D + 2D ? 3D interpenetrated, and 3D self-penetrated divalent metal terephthalate bis(pyridylformyl)piperazine coordination polymers.  

PubMed

Divalent metal coordination polymers containing terephthalate (tere) and bis(4-pyridylformyl)piperazine (bpfp) show diverse and interesting two-dimensional (2D) interpenetrated, three-dimensional (3D) self-penetrated, or one-dimensional (1D) polyrotaxane topological features. Isostructural {[M(tere)(bpfp)(H(2)O)(2)]4H(2)O}(n) phases (1, Zn; 2, Co) exhibit mutually inclined 2D + 2D ? 3D interpenetration of gridlike layers. {[Cd(4)(tere)(4)(bpfp)(3)(H(2)O)(2)]8H(2)O}(n) (3) possesses a novel 3,4,8-connected trinodal self-penetrated network with (4.6(2))(2)(4(2)6(16)8(7)10(3))(4(2)6(4))(2) topology. [Zn(2)Cl(2)(tere)(bpfp)(2)](n) (4) is the first example of a 1D + 1D ? 1D polyrotaxane coordination polymer, to the best of our knowledge. Metal coordination geometry plays a crucial role in dictating the overall dimensionality in this system. Thermal decomposition behavior and luminescent properties of the d(10) configuration metal derivatives are also presented herein. PMID:21776990

Wang, Curtis Y; Wilseck, Zachary M; LaDuca, Robert L

2011-09-19

334

Information geometry of adaptive systems  

Microsoft Academic Search

An adaptive system works in a stochastic environment so that its behavior is represented by a probability distribution, e.g., a conditional probability density of the output conditioned on the input. Information geometry is a powerful tool to study the intrinsic geometry of parameter spaces related to probability distributions. The article investigates the local Riemannian metric and topological singular structures of

Shun-ichi Amari; Tomoko Ozeki; Hyeyoung Park

2000-01-01

335

Analytic Geometry, A Tentative Guide.  

ERIC Educational Resources Information Center

This teacher's guide for a semester course in analytic geometry is based on the text "Analytic Geometry" by W. K. Morrill. Included is a daily schedule of suggested topics and homework assignments. Specific teaching hints are also given. The content of the course includes point and plane vectors, straight lines, point and space vectors, planes,

Helwig, G. Alfred; And Others

336

Cyclopean geometry of binocular vision  

Microsoft Academic Search

The geometry of binocular projection is analyzed in relation to the primate visual system. An oculomotor pa- rameterization that includes the classical vergence and version angles is defined. It is shown that the epipolar geometry of the system is constrained by binocular coordination of the eyes. A local model of the scene is adopted in which depth is measured relative

Miles Hansard; Radu Horaud

2008-01-01

337

Krppel-Like Factor 9 Promotes Hepatic Cytochrome P450 2D6 Expression during Pregnancy in CYP2D6-Humanized Mice.  

PubMed

Cytochrome P450 2D6 (CYP2D6), a major drug-metabolizing enzyme, is responsible for metabolism of approximately 25% of marketed drugs. Clinical evidence indicates that metabolism of CYP2D6 substrates is increased during pregnancy, but the underlying mechanisms remain unclear. To identify transcription factors potentially responsible for CYP2D6 induction during pregnancy, a panel of genes differentially expressed in the livers of pregnant versus nonpregnant CYP2D6-humanized (tg-CYP2D6) mice was compiled via microarray experiments followed by real-time quantitative reverse-transcription polymerase chain reaction(qRT-PCR) verification. As a result, seven transcription factors-activating transcription factor 5 (ATF5), early growth response 1 (EGR1), forkhead box protein A3 (FOXA3), JUNB, Krppel-like factor 9 (KLF9), KLF10, and REV-ERB?-were found to be up-regulated in liver during pregnancy. Results from transient transfection and promoter reporter gene assays indicate that KLF9 itself is a weak transactivator of CYP2D6 promoter but significantly enhances CYP2D6 promoter transactivation by hepatocyte nuclear factor 4 (HNF4?), a known transcriptional activator of CYP2D6 expression. The results from deletion and mutation analysis of CYP2D6 promoter activity identified a KLF9 putative binding motif at -22/-14 region to be critical in the potentiation of HNF4?-induced transactivation of CYP2D6. Electrophoretic mobility shift assays revealed a direct binding of KLF9 to the putative KLF binding motif. Results from chromatin immunoprecipitation assay showed increased recruitment of KLF9 to CYP2D6 promoter in the livers of tg-CYP2D6 mice during pregnancy. Taken together, our data suggest that increased KLF9 expression is in part responsible for CYP2D6 induction during pregnancy via the potentiation of HNF4? transactivation of CYP2D6. PMID:25217496

Koh, Kwi Hye; Pan, Xian; Zhang, Wei; McLachlan, Alan; Urrutia, Raul; Jeong, Hyunyoung

2014-12-01

338

The FE-BIE technique applied to some 2-D problems relevant to electromagnetic compatibility: optimal choice of mechanisms to take into account periodicity  

Microsoft Academic Search

A study of mechanisms to account for periodicity when modeling two-dimensional (2-D) structures with a hybrid finite-element boundary integral equation (FE-BIE) method is presented. These techniques are either based on the use of Green's functions or on the application of the Floquet-Bloch theorem as a periodic boundary condition. The described formalism can be used to model very diverse problem geometries

Hendrik Rogier; Bart Baekelandt; Frank Olyslager; Danil De Zutter

2000-01-01

339

Optical geometry across the horizon  

E-print Network

In a companion paper (Jonsson and Westman, Class. Quantum Grav. 23 (2006) 61), a generalization of optical geometry, assuming a non-shearing reference congruence, is discussed. Here we illustrate that this formalism can be applied to a finite four-volume of any spherically symmetric spacetime. In particular we apply the formalism, using a non-static reference congruence, to do optical geometry across the horizon of a static black hole. While the resulting geometry in principle is time dependent, we can choose the reference congruence in such a manner that an embedding of the geometry always looks the same. Relative to the embedded geometry the reference points are then moving. We discuss the motion of photons, inertial forces and gyroscope precession in this framework.

Rickard Jonsson

2007-08-19

340

Towards automatic calibration of 2-D flood propagation models  

NASA Astrophysics Data System (ADS)

Hydraulic models for flood propagation description are an essential tool in many fields and are used, for example, for flood hazard and risk assessments, evaluation of flood control measures, etc. Nowadays there are many models of different complexity regarding the mathematical foundation and spatial dimensions available, and most of them are comparatively easy to operate due to sophisticated tools for model setup and control. However, the calibration of these models is still underdeveloped in contrast to other models like e.g. hydrological models or models used in ecosystem analysis. This has two primary reasons: first, lack of relevant data against which the models can be calibrated, because flood events are very rarely monitored due to the disturbances inflicted by them and the lack of appropriate measuring equipment in place. Second, 2-D models are computationally very demanding and therefore the use of available sophisticated automatic calibration procedures is restricted in many cases. This study takes a well documented flood event in August 2002 at the Mulde River in Germany as an example and investigates the most appropriate calibration strategy for a simplified 2-D hyperbolic finite element model. The model independent optimiser PEST, that enables automatic calibrations without changing model code, is used and the model is calibrated against over 380 surveyed maximum water levels. The application of the parallel version of the optimiser showed that (a) it is possible to use automatic calibration in combination of 2-D hydraulic model, and (b) equifinality of model parameterisation can also be caused by a too large number of degrees of freedom in the calibration data in contrast to a too simple model setup. In order to improve model calibration and reduce equifinality, a method was developed to identify calibration data, resp. model setup with likely errors that obstruct model calibration.

Fabio, P.; Aronica, G. T.; Apel, H.

2010-06-01

341

Unusual formation of a stable 2D copper porphyrin network.  

PubMed

Copper(II) 5,15-bis(diethoxyphosphoryl)-10,20-diphenylporphyrin was obtained and characterized by means of cyclic voltammetry, electron paramagnetic resonance, Fourier transform infrared, and UV-visible spectroscopy. Three crystalline forms were grown and studied by means of X-ray diffraction methods (single crystal and powder). The highly electron-withdrawing effect of phosphoryl groups attached directly to the porphyrin macrocycle results in a self-assembling process, with formation of a stable 2D coordination network, which is unusual for copper(II) porphyrins. The resulting 2D structure is a rare example of an assembly based on copper(II) porphyrins where the copper(II) central metal ion is six-coordinated because of a weak interaction with two phosphoryl groups of adjacent porphyrins. The other polymorph of copper(II) 5,15-bis(diethoxyphosphoryl)-10,20-diphenylporphyrin contains individual (isolated) porphyrin molecules with four-coordinated copper(II) in a distorted porphyrin core. This polymorph can be obtained only by slow diffusion of a copper acetate/methanol solution into solutions of free base 5,15-bis(diethoxyphosphoryl)-10,20-diphenylporphyrin in chloroform. It converts to the 2D structure after dissolution in chloroform followed by consecutive crystallizations, using slow diffusion of hexane. A six-coordinated copper(II) porphyrin containing two axially coordinated dioxane molecules was also obtained and characterized by X-ray diffraction crystallography. The association of copper(II) 5,15-bis(diethoxyphosphoryl)-10,20-diphenylporphyrin in solution was also studied. PMID:23297696

Sinelshchikova, Anna A; Nefedov, Sergey E; Enakieva, Yulia Yu; Gorbunova, Yulia G; Tsivadze, Aslan Yu; Kadish, Karl M; Chen, Ping; Bessmertnykh-Lemeune, Alla; Stern, Christine; Guilard, Roger

2013-01-18

342

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

E-print Network

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 ­ PLEASE READ PAGES 7-9 (*140-*142 ­ 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.

343

Effective diffusion coefficient in 2D periodic channels.  

PubMed

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)]. PMID:25318709

Kalinay, Pavol

2014-10-14

344

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

345

2D Magneto-optical trapping of diatomic molecules.  

PubMed

We demonstrate one- and two-dimensional transverse laser cooling and magneto-optical trapping of the polar molecule yttrium (II) oxide (YO). In a 1D magneto-optical trap (MOT), we characterize the magneto-optical trapping force and decrease the transverse temperature by an order of magnitude, from 25 to 2 mK, limited by interaction time. In a 2D MOT, we enhance the intensity of the YO beam and reduce the transverse temperature in both transverse directions. The approach demonstrated here can be applied to many molecular species and can also be extended to 3D. PMID:25166984

Hummon, Matthew T; Yeo, Mark; Stuhl, Benjamin K; Collopy, Alejandra L; Xia, Yong; Ye, Jun

2013-04-01

346

Black liquor gasification phase 2D final report  

SciTech Connect

This report covers work conducted by Rockwell International under Amendment 5 to Subcontract STR/DOE-12 of Cooperative Agreement DE-AC-05-80CS40341 between St. Regis Corporation (now Champion International) and the Department of Energy (DOE). The work has been designated Phase 2D of the overall program to differentiate it from prior work under the same subcontract. The overall program is aimed at demonstrating the feasibility of and providing design data for the Rockwell process for gasifying Kraft black liquor. In this process, concentrated black liquor is converted into low-Btu fuel gas and reduced melt by reaction with air in a specially designed gasification reactor.

Kohl, A.L.; Stewart, A.E.

1988-06-01

347

Numerical refocusing of 2d-VISAR data  

NASA Astrophysics Data System (ADS)

Two dimensional velocity interferometer (2d-VISAR) data can be treated as a kind of hologram, since fringes recorded by the interferometer manifest both phase and magnitude information about changes in the optical field of the target, over an image. By the laws of diffraction, knowledge of the optical field at one focal plane can be used to calculate the optical field at another focal plane. Hence a numerical re-focusing operation can be performed on the data post-experiment, which can bring into focus narrow features that were recorded in an out of focus configuration. Demonstration on shocked Si data is shown.

Erskine, David J.; Smith, R. F.; Bolme, C.; Ali, S.; Celliers, P. M.; Collins, G. W.

2014-05-01

348

3D rotational diffusion microrheology using 2D video microscopy  

E-print Network

We propose a simple way to perform three-dimensional (3D) rotational microrheology using two-dimensional (2D) video microscopy. The 3D rotational brownian motion of micrometric wires in a viscous fluid is deduced from their projection on the focal plane of an optical microscope objective. The rotational diffusion coefficient of the wires of length between 1-100 \\mu m is extracted, as well as their diameter distribution in good agreement with electron microscopy measurements. This is a promising way to characterize soft visco-elastic materials, and probe the dimensions of anisotropic objects.

Rmy Colin; Minhao Yan; Loudjy Chevry; Jean-Franois Berret; Brengre Abou

2011-05-31

349

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

350

A 5d/2d/4d correspondence  

NASA Astrophysics Data System (ADS)

We propose a correspondence between two-dimensional (0, 4) sigma models with target space the moduli spaces of r monopoles, and four-dimensional {N}=4 , U( r) Yang-Mills theory on del Pezzo surfaces. In particular, the two- and four-dimensional BPS partition functions are argued to be equal. The correspondence relies on insights from five-dimensional supersymmetric gauge theory and its geometric engineering in M-theory, hence the name "5d/2d/4d correspondence". We provide various tests of our proposal. The most stringent ones are for r = 1, for which we prove the equality of partition functions.

Haghighat, Babak; Manschot, Jan; Vandoren, Stefan

2013-03-01

351

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

352

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

353

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

PubMed

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. PMID:25230002

Podesta, Mark; Persoon, Lucas C G G; Verhaegen, Frank

2014-10-21

354

All Supersymmetric Solutions of N=2, D=4 Gauged Supergravity  

E-print Network

We classify all supersymmetric solutions of minimal gauged supergravity in four dimensions. There are two classes of solutions that are distinguished by the norm of the Killing vector constructed from the Killing spinor. If the Killing vector is timelike, the solutions are determined by the geometry of a two-dimensional base-manifold. When it is lightlike, the most general BPS solution is given by an electrovac AdS travelling wave. This supersymmetric configuration was previously unknown. Generically the solutions preserve one quarter of the supersymmetry. Also in the timelike case we show that there exist new BPS solutions, which are of Petrov type I, and are thus more general than the previously known type D configurations. These geometries can be uplifted to obtain new solutions of eleven-dimensional supergravity.

Marco M. Caldarelli; Dietmar Klemm

2003-07-02

355

All supersymmetric solutions of N = 2, D = 4 gauged supergravity  

NASA Astrophysics Data System (ADS)

We classify all supersymmetric solutions of minimal gauged supergravity in four dimensions. There are two classes of solutions that are distinguished by the norm of the Killing vector constructed from the Killing spinor. If the Killing vector is timelike, the solutions are determined by the geometry of a two-dimensional base-manifold. When it is lightlike, the most general BPS solution is given by an electrovac AdS travelling wave. This supersymmetric configuration was previously unknown. Generically the solutions preserve one quarter of the supersymmetry. Also in the timelike case we show that there exist new BPS solutions, which are of Petrov type I, and are thus more general than the previously known type D configurations. These geometries can be uplifted to obtain new solutions of eleven-dimensional supergravity.

Caldarelli, Marco M.; Klemm, Dietmar

2003-09-01

356

Predicting abnormal pressure from 2-D seismic velocity modeling  

SciTech Connect

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

357

Robust 2D Topological Insulators in van der Waals Heterostructures.  

PubMed

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

358

2D collisionless magnetic reconnection: background density dependence.  

NASA Astrophysics Data System (ADS)

Even the simplest 2D configuration susceptible to magnetic reconnection (namely, Harris current sheet), possesses a number of "free parameters" that determine the dynamics and energetics of the process. Among such parameters are T_i/T_e ratio, guide field value, current sheet thickness, etc. In this report we systematically study the effect of changing the background density (from n_b/n_0=0.5 to n_b/n_0=0.003), which covers the range of lobe density values observed in the Earth's magnetotail. We performed two-dimensional Particle-in-Cell (PIC) simulations using implicit parallel code iPIC3D with double-periodic configuration. Increase of the jet front magnetic field (B_z) with n_b decrease is in agreement with 2D simulations reported previously. The elevated B_z region (magnetic field component normal to the current sheet) is several times larger than the initial current layer thickness, whereas large normal electric field (E_x) area is focused between the front and current sheet edge. Normal electric field has a bipolar profile (in the X direction), intensity scales roughly as (n_b/n_0)(-1/2) with changing n_b. In the low density case intense waves are generated near magnetic reconnection separatrices, what can be explained either by the separatrix electron flow disruption or by electron holes propagation.

Divin, Andrey; Lapenta, Giovanni; Markidis, Stefano; Andr, Mats; Khotyaintsev, Yuri; Olshevsky, Vyacheslav; Vaivads, Andris

359

Sigma-delta cellular neural network for 2D modulation.  

PubMed

Although sigma-delta modulation is widely used for analog-to-digital (A/D) converters, sigma-delta concepts are only for 1D signals. Signal processing in the digital domain is extremely useful for 2D signals such as used in image processing, medical imaging, ultrasound imaging, and so on. The intricate task that provides true 2D sigma-delta modulation is feasible in the spatial domain sigma-delta modulation using the discrete-time cellular neural network (DT-CNN) with a C-template. In the proposed architecture, the A-template is used for a digital-to-analog converter (DAC), the C-template works as an integrator, and the nonlinear output function is used for the bilevel output. In addition, due to the cellular neural network (CNN) characteristics, each pixel of an image corresponds to a cell of a CNN, and each cell is connected spatially by the A-template. Therefore, the proposed system can be thought of as a very large-scale and super-parallel sigma-delta modulator. Moreover, the spatio-temporal dynamics is designed to obtain an optimal reconstruction signal. The experimental results show the excellent reconstruction performance and capabilities of the CNN as a sigma-delta modulator. PMID:18215502

Aomori, Hisashi; Otake, Tsuyoshi; Takahashi, Nobuaki; Tanaka, Mamoru

2008-01-01

360

RCircos: an R package for Circos 2D track plots  

PubMed Central

Background Circos is a Perl language based software package for visualizing similarities and differences of genome structure and positional relationships between genomic intervals. Running Circos requires extra data processing procedures to prepare plot data files and configure files from datasets, which limits its capability of integrating directly with other software tools such as R. Recently published R Bioconductor package ggbio provides a function to display genomic data in circular layout based on multiple other packages, which increases its complexity of usage and decreased the flexibility in integrating with other R pipelines. Results We implemented an R package, RCircos, using only R packages that come with R base installation. The package supports Circos 2D data track plots such as scatter, line, histogram, heatmap, tile, connectors, links, and text labels. Each plot is implemented with a specific function and input data for all functions are data frames which can be objects read from text files or generated with other R pipelines. Conclusion RCircos package provides a simple and flexible way to make Circos 2D track plots with R and could be easily integrated into other R data processing and graphic manipulation pipelines for presenting large-scale multi-sample genomic research data. It can also serve as a base tool to generate complex Circos images. PMID:23937229

2013-01-01

361

Automatic segmentation of scaling in 2-D psoriasis skin images.  

PubMed

Psoriasis is a chronic inflammatory skin disease that affects over 3% of the population. Various methods are currently used to evaluate psoriasis severity and to monitor therapeutic response. The PASI system of scoring is widely used for evaluating psoriasis severity. It employs a visual analogue scale to score the thickness, redness (erythema), and scaling of psoriasis lesions. However, PASI scores are subjective and suffer from poor inter- and intra-observer concordance. As an integral part of developing a reliable evaluation method for psoriasis, an algorithm is presented for segmenting scaling in 2-D digital images. The algorithm is believed to be the first to localize scaling directly in 2-D digital images. The scaling segmentation problem is treated as a classification and parameter estimation problem. A Markov random field (MRF) is used to smooth a pixel-wise classification from a support vector machine (SVM) that utilizes a feature space derived from image color and scaling texture. The training sets for the SVM are collected directly from the image being analyzed giving the algorithm more resilience to variations in lighting and skin type. The algorithm is shown to give reliable segmentation results when evaluated with images with different lighting conditions, skin types, and psoriasis types. PMID:23288330

Lu, Juan; Kazmierczak, Ed; Manton, Jonathan H; Sinclair, Rodney

2013-04-01

362

Predicting non-square 2D dice probabilities  

NASA Astrophysics Data System (ADS)

The prediction of the final state probabilities of a general cuboid randomly thrown onto a surface is a problem that naturally arises in the minds of men and women familiar with regular cubic dice and the basic concepts of probability. Indeed, it was considered by Newton in 1664 (Newton 1967 The Mathematical Papers of Issac Newton vol I (Cambridge: Cambridge University Press) pp 60-1). In this paper we make progress on the 2D problem (which can be realized in 3D by considering a long cuboid, or alternatively a rectangular cross-sectioned dreidel). For the two-dimensional case we suggest that the ratio of the probabilities of landing on each of the two sides is given by \\frac{\\sqrt{{{k}^{2}}+{{l}^{2}}}-k}{\\sqrt{{{k}^{2}}+{{l}^{2}}}-l}\\frac{arctan \\frac{l}{k}}{arctan \\frac{k}{l}} where k and l are the lengths of the two sides. We test this theory both experimentally and computationally, and find good agreement between our theory, experimental and computational results. Our theory is known, from its derivation, to be an approximation for particularly bouncy or grippy surfaces where the die rolls through many revolutions before settling. On real surfaces we would expect (and we observe) that the true probability ratio for a 2D die is a somewhat closer to unity than predicted by our theory. This problem may also have wider relevance in the testing of physics engines.

Pender, G. A. T.; Uhrin, M.

2014-07-01

363

A deep search for H2D+ in protoplanetary disks  

E-print Network

The structure in density and temperature of protoplanetary disks surrounding low-mass stars is not yet well known. The protoplanetary disks mid-planes are expected to be very cold and thus depleted in molecules in gas phase, especially CO. Recent observations of molecules at very low apparent temperature (~ 6 K) challenge this current picture of the protoplanetary disk structures. We aim at constraining the physical conditions, and in particular the gas-phase CO abundance in the mid-plane of protoplanetary disks. The light molecule H2D+,is a tracer of cold and CO-depleted environment. It is therefore a good candidate to explore the disks mid-planes. We performed a deep search for H2D+ in the two well-known disks surrounding TW Hya and DM Tau using the APEX and JCMT telescopes. The analysis of the observations are done with DISKFIT, a radiative transfer code dedicated to disks. In addition, we used a chemical model describing deuterium chemistry to infer the implications of our observations on the level of CO ...

Chapillon, E; Guilloteau, S; Du, F

2011-01-01

364

Mass loss in 2D rotating stellar models  

SciTech Connect

Radiatively driven mass loss is an important factor in the evolution of massive stars . The mass loss rates depend on a number of stellar parameters, including the effective temperature and luminosity. Massive stars are also often rapidly rotating, which affects their structure and evolution. In sufficiently rapidly rotating stars, both the effective temperature and radius vary significantly as a function of latitude, and hence mass loss rates can vary appreciably between the poles and the equator. In this work, we discuss the addition of mass loss to a 2D stellar evolution code (ROTORC) and compare evolution sequences with and without mass loss. Preliminary results indicate that a full 2D calculation of mass loss using the local effective temperature and luminosity can significantly affect the distribution of mass loss in rotating main sequence stars. More mass is lost from the pole than predicted by 1D models, while less mass is lost at the equator. This change in the distribution of mass loss will affect the angular momentum loss, the surface temperature and luminosity, and even the interior structure of the star. After a single mass loss event, these effects are small, but can be expected to accumulate over the course of the main sequence evolution.

Lovekin, Caterine [Los Alamos National Laboratory; Deupree, Bob [ST MARY'S UNIV.

2010-10-05

365

Peak width issues with generalised 2D correlation NMR spectroscopy  

NASA Astrophysics Data System (ADS)

Two-dimensional spectral correlation analysis is shown to be sensitive to fluctuations in spectral peak width as a function of perturbation variable. This is particularly significant where peak width fluctuations are of similar order of magnitude as the peak width values themselves and where changes in peak width are not random but are, for example, proportional to intensity. In such cases these trends appear in the asynchronous matrix as false peaks that serve to interfere with interpretation of the data. Complex, narrow band spectra such as provided by 1H NMR spectroscopy are demonstrated to be prone to such interference. 2D correlation analysis was applied to a series of NMR spectra corresponding to a commercial wine fermentation, in which the samples collected over a period of several days exhibit dramatic changes in concentration of minor and major components. The interference due to changing peak width effects is eliminated by synthesizing the recorded spectra using a constant peak width value prior to performing 2D correlation analysis.

Kirwan, Gemma M.; Adams, Michael J.

2008-12-01

366

Fluctuation geometry: a counterpart approach of inference geometry  

NASA Astrophysics Data System (ADS)

Starting from an axiomatic perspective, fluctuation geometry is developed as a counterpart approach of inference geometry. This approach is inspired on the existence of a notable analogy between the general theorems of inference theory and the general fluctuation theorems associated with a parametric family of distribution functions dp(I|?) = ?(I|?)dI, which describes the behavior of a set of continuous stochastic variables driven by a set of control parameters ?. In this approach, statistical properties are rephrased as purely geometric notions derived from the Riemannian structure on the manifold {M}_{\\theta } of stochastic variables I. Consequently, this theory arises as an alternative framework for applying the powerful methods of differential geometry for the statistical analysis. Fluctuation geometry has direct implications on statistics and physics. This geometric approach inspires a Riemannian reformulation of Einstein fluctuation theory as well as a geometric redefinition of the information entropy for a continuous distribution.

Velazquez, L.

2012-05-01

367

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

368

U-geometry: SL(5)  

NASA Astrophysics Data System (ADS)

Recently Berman and Perry constructed a four-dimensional {M} -theory effective action which manifests SL(5) U-duality. Here we propose an underlying differential geometry of it, under the name `SL(5) U-geometry' which generalizes the ordinary Riemannian geometry in an SL(5) compatible manner. We introduce a `semi-covariant' derivative that can be converted into fully covariant derivatives after anti-symmetrizing or contracting the SL(5) vector indices appropriately. We also derive fully covariant scalar and Ricci-like curvatures which constitute the effective action as well as the equation of motion.

Park, Jeong-Hyuck; Suh, Yoonji

2013-04-01

369

Common CYP2D6 polymorphisms affecting alternative splicing and transcription: long-range haplotypes with two regulatory variants modulate CYP2D6 activity.  

PubMed

Cytochrome P450 2D6 (CYP2D6) is involved in the metabolism of 25% of clinically used drugs. Genetic polymorphisms cause substantial variation in CYP2D6 activity and serve as biomarkers guiding drug therapy. However, genotype-phenotype relationships remain ambiguous except for poor metabolizers carrying null alleles, suggesting the presence of yet unknown genetic variants. Searching for regulatory CYP2D6 polymorphisms, we find that a SNP defining the CYP2D6*2 allele, rs16947 [R296C, 17-60% minor allele frequency (MAF)], previously thought to convey normal activity, alters exon 6 splicing, thereby reducing CYP2D6 expression at least 2-fold. In addition, two completely linked SNPs (rs5758550/rs133333, MAF 13-42%) increase CYP2D6 transcription more than 2-fold, located in a distant downstream enhancer region (>100 kb) that interacts with the CYP2D6 promoter. In high linkage disequilibrium (LD) with each other, rs16947 and the enhancer SNPs form haplotypes that affect CYP2D6 enzyme activity in vivo. In a pediatric cohort of 164 individuals, rs16947 alone (minor haplotype frequency 28%) was associated with reduced CYP2D6 metabolic activity (measured as dextromethorphan/metabolite ratios), whereas rs5758550/rs133333 alone (frequency 3%) resulted in increased CYP2D6 activity, while haplotypes containing both rs16947 and rs5758550/rs133333 were similar to the wild-type. Other alleles used in biomarker panels carrying these variants such as CYP2D6*41 require re-evaluation of independent effects on CYP2D6 activity. The occurrence of two regulatory variants of high frequency and in high LD, residing on a long haplotype, highlights the importance of gene architecture, likely shaped by evolutionary selection pressures, in determining activity of encoded proteins. PMID:23985325

Wang, Danxin; Poi, Ming J; Sun, Xiaochun; Gaedigk, Andrea; Leeder, J Steven; Sadee, Wolfgang

2014-01-01

370

Emergent geometry from quantized spacetime  

SciTech Connect

We examine the picture of emergent geometry arising from a mass-deformed matrix model. Because of the mass deformation, a vacuum geometry turns out to be a constant curvature spacetime such as d-dimensional sphere and (anti-)de Sitter spaces. We show that the mass-deformed matrix model giving rise to the constant curvature spacetime can be derived from the d-dimensional Snyder algebra. The emergent geometry beautifully confirms all the rationale inferred from the algebraic point of view that the d-dimensional Snyder algebra is equivalent to the Lorentz algebra in (d+1)-dimensional flat spacetime. For example, a vacuum geometry of the mass-deformed matrix model is completely described by a G-invariant metric of coset manifolds G/H defined by the Snyder algebra. We also discuss a nonlinear deformation of the Snyder algebra.

Yang, Hyun Seok [School of Physics, Korea Institute for Advanced Study, Seoul 130-012 (Korea, Republic of); Institute for the Early Universe, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Sivakumar, M. [School of Physics, University of Hyderabad, Hyderabad 500046 (India)

2010-08-15

371

Logic, Geometry And Probability Theory  

E-print Network

We discuss the relationship between logic, geometry and probability theory under the light of a novel approach to quantum probabilities which generalizes the method developed by R. T. Cox to the quantum logical approach to physical theories.

Federico Holik

2013-11-29

372

External-Memory Computational Geometry  

E-print Network

In this paper we give new techniques for designing e cient algorithms for computational geometry prob- lems that are too large to be solved in internal mem- ory. We use these techniques to develop optimal and practical ...

Goodrich, Michael T.; Tsay, Jyh-Jong; Vengroff, Darren Erik; Vitter, Jeffrey Scott

1993-01-01

373

A novel ULA-based geometry for improving AOA estimation  

NASA Astrophysics Data System (ADS)

Due to relatively simple implementation, Uniform Linear Array (ULA) is a popular geometry for array signal processing. Despite this advantage, it does not have a uniform performance in all directions and Angle of Arrival (AOA) estimation performance degrades considerably in the angles close to endfire. In this article, a new configuration is proposed which can solve this problem. Proposed Array (PA) configuration adds two elements to the ULA in top and bottom of the array axis. By extending signal model of the ULA to the new proposed ULA-based array, AOA estimation performance has been compared in terms of angular accuracy and resolution threshold through two well-known AOA estimation algorithms, MUSIC and MVDR. In both algorithms, Root Mean Square Error (RMSE) of the detected angles descends as the input Signal to Noise Ratio (SNR) increases. Simulation results show that the proposed array geometry introduces uniform accurate performance and higher resolution in middle angles as well as border ones. The PA also presents less RMSE than the ULA in endfire directions. Therefore, the proposed array offers better performance for the border angles with almost the same array size and simplicity in both MUSIC and MVDR algorithms with respect to the conventional ULA. In addition, AOA estimation performance of the PA geometry is compared with two well-known 2D-array geometries: L-shape and V-shape, and acceptable results are obtained with equivalent or lower complexity.

Shirvani-Moghaddam, Shahriar; Akbari, Farida

2011-12-01

374

Symmetries in Generalized Khler Geometry  

NASA Astrophysics Data System (ADS)

We define the notion of a moment map and reduction in both generalized complex geometry and generalized Khler geometry. As an application, we give very simple explicit constructions of bi-Hermitian structures on mathbb{C}mathbb{P}N, Hirzebruch surfaces, the blow up of mathbb{C}mathbb{P}N at arbitrarily many points, and other toric varieties, as well as complex Grassmannians.

Lin, Yi; Tolman, Susan

2006-11-01

375

Electrical spin injection in 2D semiconductors and topological insulators  

SciTech Connect

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

376

Patterning nanoparticles into rings by "2-D Pickering emulsions".  

PubMed

We present a simple method for the two-dimensional self-assembly of CdSe/ZnS quantum dots (QDs) into well-defined rings at the air/water interface, through the formation of "2-D Pickering emulsions". Surfactant molecules assemble at the air/water interface into islands that are subsequently surrounded by adsorption of QDs from the aqueous subphase. The QD rings emanating from this process range from ?100 nm to several micrometers in diameter, as characterized by atomic force microscopy, scanning eectron microscopy, and fluorescence microscopy. The deposition and alignment of QD rings onto large areas (cm(2)) were demonstrated by dip-coating onto a substrate. This simple method produces rings of QDs without the need for any templating or fabrication steps. PMID:24645916

Lee, Cheol Hee; Crosby, Alfred J; Hayward, Ryan C; Emrick, Todd

2014-04-01

377

CYP2D6-related oxidation polymorphism in Italy.  

PubMed

The distribution of the oxidation polymorphism related to cytochrome CYP2D6 (debrisoquine type) was determined in 246 healthy Italian volunteers. Phenotyping was based on HPLC determination of the dextrometorphan/dextrorphan concentration ratio (metabolic ratio) in urine samples collected over an 8 h interval following a single oral 30 mg dose of dextromethorphan hydrobromide. Urinary excretion of dextromethorphan showed a wide interindividual variability, ranging from < or = 0.04 to 3.9% and from 0.5 to 79.6% of the dose, respectively. Metabolic ratios ranged from < or = 0.001 to 6.6. Eleven of the 246 subjects showed a metabolic ratio greater than 0.30, indicating that 4.5% of the population could be ascribed to the poor metabolizer status. The frequency of the poor metabolizer phenotype in this population is within the range described for other Caucasian ethnic groups. PMID:8058599

Spina, E; Campo, G M; Avenoso, A; Caputi, A P; Zuccaro, P; Pacifici, R; Gatti, G; Strada, G; Bartoli, A; Perucca, E

1994-04-01

378

Glassy Dislocation Dynamics in 2-D Colloidal Dimer Crystals  

E-print Network

Although glassy relaxation is typically associated with disorder, here we report on a new type of glassy dynamics relating to dislocations within 2-D crystals of colloidal dimers. Previous studies have demonstrated that dislocation motion in dimer crystals is restricted by certain particle orientations. Here, we drag an optically trapped particle through such dimer crystals, creating dislocations. We find a two-stage relaxation response where initially dislocations glide until encountering particles that cage their motion. Subsequent relaxation occurs logarithmically slowly through a second process where dislocations hop between caged configurations. Finally, in simulations of sheared dimer crystals, the dislocation mean squared displacement displays a caging plateau typical of glassy dynamics. Together, these results reveal a novel glassy system within a colloidal crystal.

Sharon J. Gerbode; Umang Agarwal; Desmond C. Ong; Chekesha M. Liddell; Fernando Escobedo; Itai Cohen

2010-08-11

379

2D Binary QSAR Modeling of LPA3 Receptor Antagonism  

PubMed Central

A structurally diverse dataset of 119 compounds was used to develop and validate a 2D binary QSAR model for the LPA3 receptor. The binary QSAR model was generated using an activity threshold of greater than 15% inhibition at 10M. The overall accuracy of the model on the training set was 82%. It had accuracies of 55% for active and 91% for inactive compounds, respectively. The model was validated using an external test set of 10 compounds. The accuracy on the external test set was 60% overall, identifying three out of seven actives and all three inactive compounds. This model was combined with similarity searching to rapidly screen libraries and select 14 candidate LPA3 antagonists. Experimental assays confirmed 13 of these (93%) met the 15% inhibition threshold defining actives. The successful application of the model to select candidates for screening demonstrates the power of this binary QSAR model to prioritize compound selection for experimental consideration. PMID:20356772

Fells, James I.; Tsukahara, Ryoko; Liu, Jianxiong; Tigyi, Gabor; Parrill, Abby L.

2010-01-01

380

The 2D Hubbard model on the honeycomb lattice  

E-print Network

We consider the 2D Hubbard model on the honeycomb lattice, as a model for a single layer graphene sheet in the presence of screened Coulomb interactions. At half filling and weak enough coupling, we compute the free energy, the ground state energy and we construct the correlation functions up to zero temperature in terms of convergent series; analiticity is proved by making use of constructive fermionic renormalization group methods. We show that the interaction produces a modification of the Fermi velocity and of the wave function renormalization without changing the asymptotic infrared properties of the model with respect to the unperturbed non-interacting case; this rules out the possibility of superconducting or magnetic instabilities in the ground state. We also prove that the correlations verify a Ward Identity similar to the one for massless Dirac fermions, up to asymptotically negligible corrections and a renormalization of the charge velocity.

Alessandro Giuliani; Vieri Mastropietro

2008-11-12

381

Spectrum of Relativistic Fermions in a 2d Doped Lattice  

E-print Network

Motivated by some previous work on fermions on random lattices and by suggestions that impurities could trigger parity breaking in 2d crystals, we have analyzed the spectrum of the Dirac equation on a two dimensional square lattice where sites have been removed randomly --- a doped lattice. We have found that the system is well described by a sine-Gordon action. The solitons of this model are the lattice fermions, which pick a quartic interaction due to the doping and become Thirring fermions. They also get an effective mass different from the lagrangian mass. The system seems to exhibit spontaneous symmetry breaking, exactly as it happens for a randomly triangulated lattice. The associated ``Goldstone boson" is the sine-Gordon scalar. We argue, however, that the peculiar behaviour of the chiral condensate is due to finite size effects.

D. Espriu; J. Matias

1992-04-21

382

Adaptive superplastic forming using NIKE2D with ISLAND  

SciTech Connect

Superplastic forming has emerged as an important manufacturing process for producing near-net-shape parts. The design of a superplastic forming process is more difficult than conventional manufacturing operations, and is less amenable to trial and error approaches. This paper describes a superplastic forming process design capability incorporating nonlinear finite element analysis. The material constraints to allow superplastic behavior are integrated into an external constraint equation which is solved concurrently with the nonlinear finite element equations. The implementation of this approach using the ISLAND solution control language with the nonlinear finite element code NIKE2D is discussed in detail. Superplastic forming process design problems with one and two control parameters are presented as examples.

Engelmann, B.E.; Whirley, R.G.; Raboin, P.J.

1992-07-30

383

areaDetector: Software for 2-D Detectors in EPICS  

SciTech Connect

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

384

Optimum design of 2D micro-angle sensor  

NASA Astrophysics Data System (ADS)

To improve dynamic measurement performance and resolution, an optimum design on two-dimensional (2D) micro-angle sensor based on optical internal-reflection method via critical-angle refractive index measurement is presented in the paper. The noise signals were filtered effectively by modulating laser-driven and demodulating in signal proceeding. The system's accuracy and response speed are improved further by using 16-bit high-precision AD converter and MSP430 CPU which present with a high-speed performance during signals processes such as fitting angle-voltage curve through specific arithmetic, full range and zero point calibration, filter, scaling transformation etc. The experiment results indicated that, dynamic signal measurement range can be up to +/-600arcsec, the measurement resolution can be better than 0.1arcsec, and the repeatability could be better than +/-0.5arcsec.

Liu, Qinggang; Zhao, Heng; Lou, Xiaona; Jiang, Ningchuan; Hu, Xiaotang

2008-12-01

385

The Extended Fourier Transform for 2D Spectral Estimation  

NASA Astrophysics Data System (ADS)

We present a linear algebraic method, named the e Xtended Fourier Transform (XFT), for spectral estimation from truncated time signals. The method is a hybrid of the discrete Fourier transform (DFT) and the regularized resolvent transform (RRT) (J. Chen et al., J. Magn. Reson.147, 129-137 (2000)). Namely, it estimates the remainder of a finite DFT by RRT. The RRT estimation corresponds to solution of an ill-conditioned problem, which requires regularization. The regularization depends on a parameter, q, that essentially controls the resolution. By varying q from 0 to ? one can "tune" the spectrum between a high-resolution spectral estimate and the finite DFT. The optimal value of q is chosen according to how well the data fits the form of a sum of complex sinusoids and, in particular, the signal-to-noise ratio. Both 1D and 2D XFT are presented with applications to experimental NMR signals.

Armstrong, Geoffrey S.; Mandelshtam, Vladimir A.

2001-11-01

386

TOPAZ2D validation status report, August 1990  

SciTech Connect

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

387

Spectral dimension of quantum geometries  

NASA Astrophysics Data System (ADS)

The spectral dimension is an indicator of geometry and topology of spacetime and a tool to compare the description of quantum geometry in various approaches to quantum gravity. This is possible because it can be defined not only on smooth geometries but also on discrete (e.g., simplicial) ones. In this paper, we consider the spectral dimension of quantum states of spatial geometry defined on combinatorial complexes endowed with additional algebraic data: the kinematical quantum states of loop quantum gravity (LQG). Preliminarily, the effects of topology and discreteness of classical discrete geometries are studied in a systematic manner. We look for states reproducing the spectral dimension of a classical space in the appropriate regime. We also test the hypothesis that in LQG, as in other approaches, there is a scale dependence of the spectral dimension, which runs from the topological dimension at large scales to a smaller one at short distances. While our results do not give any strong support to this hypothesis, we can however pinpoint when the topological dimension is reproduced by LQG quantum states. Overall, by exploring the interplay of combinatorial, topological and geometrical effects, and by considering various kinds of quantum states such as coherent states and their superpositions, we find that the spectral dimension of discrete quantum geometries is more sensitive to the underlying combinatorial structures than to the details of the additional data associated with them.

Calcagni, Gianluca; Oriti, Daniele; Thrigen, Johannes

2014-07-01

388

Tensor network states and geometry  

E-print Network

Tensor network states are used to approximate ground states of local Hamiltonians on a lattice in D spatial dimensions. Different types of tensor network states can be seen to generate different geometries. Matrix product states (MPS) in D=1 dimensions, as well as projected entangled pair states (PEPS) in D>1 dimensions, reproduce the D-dimensional physical geometry of the lattice model; in contrast, the multi-scale entanglement renormalization ansatz (MERA) generates a (D+1)-dimensional holographic geometry. Here we focus on homogeneous tensor networks, where all the tensors in the network are copies of the same tensor, and argue that certain structural properties of the resulting many-body states are preconditioned by the geometry of the tensor network and are therefore largely independent of the choice of variational parameters. Indeed, the asymptotic decay of correlations in homogeneous MPS and MERA for D=1 systems is seen to be determined by the structure of geodesics in the physical and holographic geometries, respectively; whereas the asymptotic scaling of entanglement entropy is seen to always obey a simple boundary law -- that is, again in the relevant geometry. This geometrical interpretation offers a simple and unifying framework to understand the structural properties of, and helps clarify the relation between, different tensor network states. In addition, it has recently motivated the branching MERA, a generalization of the MERA capable of reproducing violations of the entropic boundary law in D>1 dimensions.

G. Evenbly; G. Vidal

2011-06-06

389

The Common Geometry Module (CGM).  

SciTech Connect

The Common Geometry Module (CGM) is a code library which provides geometry functionality used for mesh generation and other applications. This functionality includes that commonly found in solid modeling engines, like geometry creation, query and modification; CGM also includes capabilities not commonly found in solid modeling engines, like geometry decomposition tools and support for shared material interfaces. CGM is built upon the ACIS solid modeling engine, but also includes geometry capability developed beside and on top of ACIS. CGM can be used as-is to provide geometry functionality for codes needing this capability. However, CGM can also be extended using derived classes in C++, allowing the geometric model to serve as the basis for other applications, for example mesh generation. CGM is supported on Sun Solaris, SGI, HP, IBM, DEC, Linux and Windows NT platforms. CGM also includes support for loading ACIS models on parallel computers, using MPI-based communication. Future plans for CGM are to port it to different solid modeling engines, including Pro/Engineer or SolidWorks. CGM is being released into the public domain under an LGPL license; the ACIS-based engine is available to ACIS licensees on request.

Tautges, Timothy James

2004-12-01

390

Thermocapillary bubble dynamics in a 2D axis swirl domain  

NASA Astrophysics Data System (ADS)

The lack of significant buoyancy effects in zero-gravity conditions poses an issue with fluid transfer in a stagnant liquid. In this paper, bubble movement in a stagnant liquid is analysed and presented numerically using a computational fluid dynamics approach. The governing continuum and conservation equations for two-phase flow are solved using the commercial software package Ansys-Fluent v.13. The volume of fluid method is used to track the liquid/gas interface in 2D and 3D domains, which has been found to be a valuable tool for studying the phenomenon of gas-liquid interaction, and the validation results are in reasonable agreement with earlier experimental observations. The flow is driven via Marangoni influence induced by the temperature difference, which in turn drives the bubble from the cold to the hot region. The results indicate that the inherent velocity of bubbles decreases with an increase in Marangoni number; this is in agreement with the results of previous experiments conducted in Kang et al. (Microgravity Sci Technol 20:67-71, 2008). Some three-dimensional simulations will also be performed to compare and examine the results with two-dimensional simulations. The thermocapillary bubble flow in a 2D swirl axisymmetry driven by the rotation of the walls was also carried out for different angular velocities in zero gravity. The bubble migration speed was found to decrease with increasing angular velocity. This occurrence is due to an increase in the pressure gradient between the cylinder's outer wall and the axis of rotation, which forces the lowest pressure region to shift from the sides of the bubble to the axis of rotation. A deformation of the bubble and the formation of the two vortices inside the bubble are also observed. These new and original findings aim to help support research into space applications.

Alhendal, Yousuf; Turan, Ali

2014-09-01

391

E-2D Advanced Hawkeye: primary flight display  

NASA Astrophysics Data System (ADS)

This paper is a response to the challenge of providing a large area avionics display for the E-2D AHE aircraft. The resulting display design provides a pilot with high-resolution visual information content covering an image area of almost three square feet (Active Area of Samsung display = 33.792cm x 27.0336 cm = 13.304" x 10.643" = 141.596 square inches = 0.983 sq. ft x 3 = 2.95 sq. ft). The avionics display application, design and performance being described is the Primary Flight Display for the E-2D Advanced Hawkeye aircraft. This cockpit display has a screen diagonal size of 17 inches. Three displays, with minimum bezel width, just fit within the available instrument panel area. The significant design constraints of supporting an upgrade installation have been addressed. These constraints include a display image size that is larger than the mounting opening in the instrument panel. This, therefore, requires that the Electromagnetic Interference (EMI) window, LCD panel and backlight all fit within the limited available bezel depth. High brightness and a wide dimming range are supported with a dual mode Cold Cathode Fluorescent Tube (CCFT) and LED backlight. Packaging constraints dictated the use of multiple U shaped fluorescent lamps in a direct view backlight design for a maximum display brightness of 300 foot-Lamberts. The low intensity backlight levels are provided by remote LEDs coupled through a fiber optic mesh. This architecture generates luminous uniformity within a minimum backlight depth. Cross-cockpit viewing is supported with ultra-wide field-of-view performance including contrast and the color stability of an advanced LCD cell design supports. Display system design tradeoffs directed a priority to high optical efficiency for minimum power and weight.

Paolillo, Paul W.; Saxena, Ragini; Garruba, Jonathan; Tripathi, Sanjay; Blanchard, Randy

2006-05-01

392

4D-2D projection of Lorentz-violating Myers-Pospelov QED  

NASA Astrophysics Data System (ADS)

We consider the four-dimensional quantum electrodynamics extended with Myers-Pospelov Lorentz-violating dimension-five operators to investigate 4D-2D projection. In projecting out the 4D theory down to a 2D theory, we get analogs of these operators. Namely, we obtain a new two-dimensional theory with corresponding scalar and fermionic 2D Myers-Pospelov Lorentz-violating dimension-three operators. New defect structures can also be found from this new projected-out 2D scalar sector. Furthermore, we also show that this 2D scalar sector can also be radiatively induced through the new 2D fermionic sector.

Brito, F. A.; Guimaraes, M. S.; Passos, E.; Sampaio, P.; Wotzasek, C.

2012-11-01

393

Comparison of Super Resolution Reconstruction Acquisition Geometries for Use in Mouse Phenotyping  

PubMed Central

3D isotropic imaging at high spatial resolution (30100 microns) is important for comparing mouse phenotypes. 3D imaging at high spatial resolutions is limited by long acquisition times and is not possible in many in vivo settings. Super resolution reconstruction (SRR) is a postprocessing technique that has been proposed to improve spatial resolution in the slice-select direction using multiple 2D multislice acquisitions. Any 2D multislice acquisition can be used for SRR. In this study, the effects of using three different low-resolution acquisition geometries (orthogonal, rotational, and shifted) on SRR images were evaluated and compared to a known standard. Iterative back projection was used for the reconstruction of all three acquisition geometries. The results of the study indicate that super resolution reconstructed images based on orthogonally acquired low-resolution images resulted in reconstructed images with higher SNR and CNR in less acquisition time than those based on rotational and shifted acquisition geometries. However, interpolation artifacts were observed in SRR images based on orthogonal acquisition geometry, particularly when the slice thickness was greater than six times the inplane voxel size. Reconstructions based on rotational geometry appeared smoother than those based on orthogonal geometry, but they required two times longer to acquire than the orthogonal LR images. PMID:24174930

Clymer, Bradley D.; Bratasz, Anna; Powell, Kimerly A.

2013-01-01

394

2-D Circulation Control Airfoil Benchmark Experiments Intended for CFD Code Validation  

NASA Technical Reports Server (NTRS)

A current NASA Research Announcement (NRA) project being conducted by Georgia Tech Research Institute (GTRI) personnel and NASA collaborators includes the development of Circulation Control (CC) blown airfoils to improve subsonic aircraft high-lift and cruise performance. The emphasis of this program is the development of CC active flow control concepts for both high-lift augmentation, drag control, and cruise efficiency. A collaboration in this project includes work by NASA research engineers, whereas CFD validation and flow physics experimental research are part of NASA s systematic approach to developing design and optimization tools for CC applications to fixed-wing aircraft. The design space for CESTOL type aircraft is focusing on geometries that depend on advanced flow control technologies that include Circulation Control aerodynamics. The ability to consistently predict advanced aircraft performance requires improvements in design tools to include these advanced concepts. Validation of these tools will be based on experimental methods applied to complex flows that go beyond conventional aircraft modeling techniques. This paper focuses on recent/ongoing benchmark high-lift experiments and CFD efforts intended to provide 2-D CFD validation data sets related to NASA s Cruise Efficient Short Take Off and Landing (CESTOL) study. Both the experimental data and related CFD predictions are discussed.

Englar, Robert J.; Jones, Gregory S.; Allan, Brian G.; Lin, Johb C.

2009-01-01

395

Supramolecular Self-Assembly of -conjugated Hydrocarbons via 2D Cooperative CH/ Interaction  

SciTech Connect

Supramolecular self-assembly on well-defined surfaces provides access to a multitude of nanoscale architectures, including clusters of distinct symmetry and size. The driving forces underlying supramolecular structures generally involve both graphoepitaxy and weak directional nonconvalent interactions. Here we show that functionalizing a benzene molecule with an ethyne group introduces attractive interactions in a 2D geometry, which would otherwise be dominated by intermolecular repulsion. Furthermore, the attractive interactions enable supramolecular self-assembly, wherein a subtle balance between very weak CH/{pi} bonding and molecule-surface interactions produces a well-defined 'magic' dimension and chirality of supramolecular clusters. The nature of the process is corroborated by extensive scanning tunneling microscopy/spectroscopy (STM/S) measurements and ab initio calculations, which emphasize the cooperative, multicenter characters of the CH/{pi} interaction. This work points out new possibilities for chemical functionalization of {pi}-conjugated hydrocarbon molecules that may allow for the rational design of supramolecular clusters with a desired shape and size.

Sumpter, Bobby G [ORNL; Fuentes-Cabrera, Miguel A [ORNL

2011-01-01

396

Extended States and Critical Behavior in 2D and 3D Amorphous Conductors  

NASA Astrophysics Data System (ADS)

With a tight binding treatment for one, two and three dimensional systems, we calculate and analyze electronic states in a conductor with topological disorder, or no correlations among the positions of the hopping sites. The Inverse Participation Ratio (IPR) is used to characterize carrier wave functions with respect to localization. We consider an exponentially decaying hopping integral with range (or ``Bohr radius'') l. Using two complementary finite size scaling techniques to extrapolate to the bulk limit (both methods exploit critical behavior in different ways to locate the energy marking the boundary between extended and localized wave functions) which nevertheless yield identical results, we obtain phase diagrams showing regions where states are extended and domains of localized states. We find exclusively localized wave functions for 1D geometries, irrespective of l. In the 2D case, states are localized below a threshold length scale lc 1.0, with a finite fraction of states extended for l > lc. For 3D systems, the extended phase is flanked by regions of localized states and bounded by two mobility edges. The swath of extended states, broad for l 1, becomes narrower with decreasing l, scaling asymptotically as e^-A/l for l 1.

Priour, Donald

2012-02-01

397

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

SciTech Connect

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

398

AUTOTEM - Automated geometry meshing and heat conduction calculation  

NASA Technical Reports Server (NTRS)

Temperature distribution for an arbitrary irregular body is calculated by AUTOTEM, which generates required input data automatically by computer. Temperature distribution is calculated for a two-dimensional plane section in /x,y/ coordinates or for an axisymmetric irregular body in /r,z/ coordinates.

Lee, A. Y.; Wells, K. J.

1971-01-01

399

2-D Stress Accumulation Analysis of the North Anatolian Fault East of the Marmara Sea  

NASA Astrophysics Data System (ADS)

On August 17th, 1999, a magnitude 7.4 earthquake shook the city of Kocaeli (Izmit), Turkey killing over 17,000 people. The epicenter was approximately 100-km east of Turkey's largest city, Istanbul, along the North Anatolian Fault (NAF) system. This 1600-km long, strike-slip boundary divides the Anatolian plate and the Eurasian plate. The NAF slips at an average rate of 2-3-cm y-1, and has an earthquake recurrence interval of approximately 300 years. To further understand the NAF system and its dynamics, a simplified 2-D mesh model was developed to describe fault stress accumulation along an ~110-km stretch of the NAF system east of the Marmara Sea. This region was selected because it is where two sets of faults within the NAF system converge, and then diverge. One set diverges to the NW to bound the northern rim of the Marmara Sea, while the second set continues to the SW along the southern rim of the Marmara Sea. The 2-D mesh separates the study area into three geologic provinces defined by these faults: the Istanbul Zone, the Armatlu-Almacik Zone, and the Sakarya Zone. The resulting mesh was then processed using the Numerical Manifold Method (NMM) and PyLith, a finite element code deformation software. The NMM and PyLith simulations model the stress field in the region by employing surface fault geometry, rock physics parameters of the surface geology, and relative plate motions as determined by GPS velocities from Turkey's extensive network of GPS stations. Surface geology was simplified into the three rock types, and rock physics parameters were assigned using general physical parameters for each rock type and extrapolating further data from the Canadian Rock Physics Database. For the three zones, an average value for density and P-wave velocity was assigned using this database, and these averaged values were used to calculate S-wave velocity, shear modulus, bulk modulus, Young's modulus, Poisson's ratio, and Lam's first parameter for use in processing the mesh model. To further validate the results of the simulations, we analyzed lineaments from a digital elevation model (DEM) and a daytime ASTER image. Lineaments were then plotted on a rose diagram to determine the directions of principle stress, which trend SE-NW (sigma-1), and SW-NE (sigma-3). The 2-D geophysical model allows for changes in stress direction and magnitude to be depicted over the entire region, while the lineament analysis is a potential sum of how stress has evolved over time. The map of modeled stress accumulation allows us to evaluate the potential geometry of the faults in this section of the NAF system as well as highlight which faults are host to more stress, and thus predict how that stress may migrate to the east, either north or south of the Marmara Sea. Based on a hundred year record of seismicity in Turkey, it is theorized that a higher magnitude of total stress accumulation will migrate south of the Marmara Sea along the SW-NE trending faults within our region of interest. A greater understanding of the stress field will allow researchers to evaluate the seismic risk within the larger region of Eastern Turkey, as well as understand fault dynamics along the NAF.

Karimi, B.; McQuarrie, N.; Harbert, W.; Lin, J.

2011-12-01

400

Measurement of sputtering yields of CD_4,C_2D2 and C_2D4 at the carbon divertor plate of JT-60U  

NASA Astrophysics Data System (ADS)

Under cold and dense divertor conditions, the chemical erosion process reduces the lifetime of carbon divertor tiles in fusion reactors. It is important to evaluate the chemical sputtering yield at the divertor exposed to the high particle flux in large tokamaks such as JT-60U. Spectral bands of CD and C2 have been measured in order to evaluate the chemical sputtering yields of CD4 ,C_2D2 and C_2D4 in L-mode discharges. From the intensities of the spectral bands, the yields of CD4 and C_2D_2+C_2D4 are estimated to be about 1-2% in an ion flux range of 0.2-210^23m-2/s. The yields of CD4 and C_2D_2+C_2D4 in this work are about half compared with laboratory data(R.Yamada J.Nucl.Mater. 145-147(1987)359) in a low ion flux range ( ~210^19m-2/s). However, the ratio of CD4 to C_2D_2+C_2D4 is almost the same in both experiments. The number of carbon atoms originating from C_2D2 and C_2D4 is comparable to or larger than that from CD_4. Therefore, heavy hydrocarbons as well as CD4 have the contribution to carbon impurity generation in a wide range of the ion flux. This work is the first quantitative estimation of the sputtering yields of C_2D2 and C_2D4 in tokamaks.

Nakano, T.; Kubo, H.; Higashijima, S.; Sugie, T.; Asakura, N.; Itami, K.

2000-10-01

401

Highly resolved double absorption 2D NMR spectra from complex severely truncated 2D phase-modulated signals by filter-diagonalization-averaging method  

Microsoft Academic Search

Application of the filter diagonalization method (FDM) to the spectral estimation of purely phase-modulated 2D-J NMR data is described. It is shown that obtaining an entire 2D line list of spectral parameters is not a prerequisite for constructing a spectral estimate of the data. Common problems with 2D FT analysis, such as phase-twist lineshapes, spectral broadening from the time-frequency uncertainty

Vladimir A. Mandelshtam; Nathan D. Taylor; Haitao Hu; Mari Smith; A. J. Shaka

1999-01-01

402

Antenna-coupled microbolometer based uncooled 2D array and camera for 2D real-time terahertz imaging  

NASA Astrophysics Data System (ADS)

CEA-Leti has developed a monolithic large focal plane array bolometric technology optimized for 2D real-time imaging in the terahertz range. Each pixel consists in a silicon microbolometer coupled to specific antennas and a resonant quarter-wavelength cavity. First prototypes of imaging arrays have been designed and manufactured for optimized sensing in the 1-3.5THz range where THz quantum cascade lasers are delivering high optical power. NEP in the order of 1 pW/sqrt(Hz) has been assessed at 2.5 THz. This paper reports the steps of this development, starting from the pixel level, to an array associated monolithically to its CMOS ROIC and finally a stand-alone camera. For each step, modeling, technological prototyping and experimental characterizations are presented.

Simoens, F.; Meilhan, J.; Gidon, S.; Lasfargues, G.; Lalanne Dera, J.; Ouvrier-Buffet, J. L.; Pocas, S.; Rabaud, W.; Guellec, F.; Dupont, B.; Martin, S.; Simon, A. C.

2013-09-01

403

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

SciTech Connect

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

404

Digit ratio (2D:4D) moderates the impact of an aggressive music video on aggression  

Microsoft Academic Search

Digit ratio (2D:4D) is a sexually dimorphic trait. Men have relatively shorter index fingers (2D) compared to ring fingers (4D) than women. Evidence suggests that more masculine ratios are influenced by higher prenatal testosterone levels. Testosterone and aggression are related and accordingly evidence suggests that male 2D:4D is related to physical aggression [Bailey and Hurd, 2005] and female 2D:4D is

Kobe Millet; Siegfried Dewitte

2007-01-01

405

Stochastic 2D Hydrodynamical Type Systems: Well Posedness and Large Deviations  

SciTech Connect

We deal with a class of abstract nonlinear stochastic models, which covers many 2D hydrodynamical models including 2D Navier-Stokes equations, 2D MHD models and the 2D magnetic Benard problem and also some shell models of turbulence. We state the existence and uniqueness theorem for the class considered. Our main result is a Wentzell-Freidlin type large deviation principle for small multiplicative noise which we prove by a weak convergence method.

Chueshov, Igor, E-mail: chueshov@univer.kharkov.u [Kharkov National University, Department of Mechanics and Mathematics (Ukraine); Millet, Annie, E-mail: amillet@univ-paris1.f [Universites Paris 6-Paris 7, Boite Courrier 188, Laboratoire de Probabilites et Modeles Aleatoires (France)

2010-06-15

406

Characterization of the oxidation reactions catalyzed by cyp2d enzyme in rat renal microsomes  

Microsoft Academic Search

Monooxygenase activities in rat renal microsomes were determined with the substrates of hepatic CYP2D enzymes. Seven kinds of CYP2D-mediated monooxygenase activities and immunochemically determined CYP2D contents in kidneys corresponded to approximately 3 % of those in livers. Debrisoquine 4-hydroxylase and bunitrolol 4-hydroxylase in renal microsomes were inhibited almost completely by the antibody against a CYP2D enzyme purified from rat liver.

Yasuhiro Masubuchi; Kyoko Yamamoto; Tokuji Suzuki; Toshiharu Hone; Shizuo Narimatsu

1996-01-01

407

Human Erythrocyte Catalase: 2-D Crystal Nucleation and Production of Multiple Crystal Forms  

Microsoft Academic Search

Negatively stained electron microscope images are presented, showing the nucleation of two-dimensional (2-D) crystals of human erythrocyte catalase produced on mica by the negative staining-carbon film technique. Examples of the formation of partially ordered 2-D arrays and more ordered 2-D crystals are shown and the conditions required for the production of large well-ordered 2-D crystals discussed. The structural transformation of

J. Robin Harris; Andreas Holzenburg

1995-01-01

408

The 2dF Galaxy Redshift Survey: spectra and redshifts  

Microsoft Academic Search

The 2dF Galaxy Redshift Survey (2dFGRS) is designed to measure redshifts for approximately 250000 galaxies. This paper describes the survey design, the spectroscopic observations, the redshift measurements and the survey data base. The 2dFGRS uses the 2dF multifibre spectrograph on the Anglo-Australian Telescope, which is capable of observing 400 objects simultaneously over a 2 diameter field. The source catalogue for

Matthew Colless; Gavin Dalton; Steve Maddox; Will Sutherland; Peder Norberg; Shaun Cole; Joss Bland-Hawthorn; Terry Bridges; Chris Collins; Nicholas Cross; Kathryn Deeley; Roberto De Propris; Simon P. Driver; George Efstathiou; Richard S. Ellis; Karl Glazebrook; Carole Jackson; Ofer Lahav; Ian Lewis; Stuart Lumsden; Darren Madgwick; John A. Peacock; Bruce A. Peterson; Ian Price; Mark Seaborne; Keith Taylor

2001-01-01

409

Quasi 2D Materials: Raman Nanometrology and Thermal Management Applications  

NASA Astrophysics Data System (ADS)

Quasi two-dimensional (2D) materials obtained by the "graphene-like" exfoliation attracted tremendous attention. Such materials revealed unique electronic, thermal and optical properties, which can be potentially used in electronics, thermal management and energy conversion. This dissertation research addresses two separate but synergetic problems: (i) preparation and optical characterization of quasi-2D films of the bismuth-telluride (Bi 2Te3) family of materials, which demonstrate both thermoelectric and topological insulator properties; and (ii) investigation of thermal properties of composite materials prepared with graphene and few-layer graphene (FLG). The first part of dissertation reports properties of the exfoliated few-quintuple layers of Bi2Te3, Bi2Se3 and Sb 2Te3. Both non-resonant and resonant Raman scattering spectra have been investigated. It was found that the crystal symmetry breaking in few-quintuple films results in appearance of A1u-symmetry Raman peaks, which are not active in the bulk crystals. The scattering spectra measured under the 633-nm wavelength excitation reveals a number of resonant features, which could be used for analysis of the electronic and phonon processes in these materials. The obtained results help to understand the physical mechanisms of Raman scattering in the few-quintuple-thick films and can be used for nanometrology of topological insulator films on various substrates. The second part of the dissertation is dedicated to investigation of properties of composite materials prepared with graphene and FLG. It was found that the optimized mixture of graphene and multilayer graphene---produced by the high-yield inexpensive liquid-phase-exfoliation technique---can lead to an extremely strong enhancement of the cross-plane thermal conductivity K of the composite. The "laser flash" measurements revealed a record-high enhancement of K by 2300 % in the graphene-based polymer at the filler loading fraction f =10 vol. %. It was determined that the relatively high concentration of the single-layer and bilayer graphene flakes (10--15%) present simultaneously with the thicker multilayers of large lateral size ( 1 microm) were essential for the observed unusual K enhancement. Our modeling results suggest that graphene-multilayer graphene nanocomposite used as the thermal interface material outperforms those with carbon nanotubes or metal nanoparticles owing to graphene's aspect ratio and lower Kapitza resistance at the graphene-matrix interface.

Shahil, Khan Mohammad Farhan

410

The effect of turbulence on 2D magnetic reconnection  

NASA Astrophysics Data System (ADS)

Magnetic reconnection is a well known plasma process believed to lie at the heart of a variety of phenomena such as sub-storms in the Earth's magnetosphere, solar/stellar and accretion-disk flares, sawteeth activity in fusion devices, etc. During reconnection, the global magnetic field topology changes rapidly, leading to the violent release of magnetic energy. One of the outstanding theoretical challenges in this field is the understanding of the mechanism(s) responsible for such rapid changes. In single-fluid MHD, it is believed that magnetic reconnection is well described by the Sweet-Parker theory (SP), which, however, is orders of magnitude too slow to explain observations. In many cases of interest, reconnection takes place in plasmas which are fundamentally collisionless, and which cannot, therefore, be described by MHD theory. Indeed, a vast amount of numerical studies suggest that fast reconnection can be obtained when kinetic physics becomes important. However, in many astrophysical situations (e.g., inside stars and accretion disks) the density is so high that the reconnection layer is collisional and resistive MHD should apply. How, then, can reconnection be fast in these environments? Missing from the SP picture is that most, if not all, environments where reconnection occurs are likely to be turbulent. Theoretical arguments exist [Lazarian & Vishniac, ApJ 517, 700 (1999)] (LV) suggesting that indeed turbulence can significantly enhance the reconnection rate, but only in 3D. In this talk, we present the results of an extensive, high-resolution, numerical study of the effect of small-scale background turbulence on 2D magnetic reconnection [Loureiro et al., MNRAS 399, 1 (2009)]. We show that, contrary to theoretical expectations, turbulence has a very significant effect in speeding-up the 2D reconnection process, yielding a reconnection rate whose dependence on resistivity (?) is extremely weak and is even consistent with an ?-independent value. We suggest that these results point to a mechanism of turbulent enhancement of the reconnection rate which is alternative to that envisionaged by LV, and which may be related to the instability of the current sheet to the formation of multiple secondary magnetic islands (plasmoids).

Loureiro, Nuno

2010-05-01

411

Universal Entanglement Entropy in 2D Conformal Quantum Critical Points  

SciTech Connect

We study the scaling behavior of the entanglement entropy of two dimensional conformal quantum critical systems, i.e. systems with scale invariant wave functions. They include two-dimensional generalized quantum dimer models on bipartite lattices and quantum loop models, as well as the quantum Lifshitz model and related gauge theories. We show that, under quite general conditions, the entanglement entropy of a large and simply connected sub-system of an infinite system with a smooth boundary has a universal finite contribution, as well as scale-invariant terms for special geometries. The universal finite contribution to the entanglement entropy is computable in terms of the properties of the conformal structure of the wave function of these quantum critical systems. The calculation of the universal term reduces to a problem in boundary conformal field theory.

Hsu, Benjamin; Mulligan, Michael; Fradkin, Eduardo; Kim, Eun-Ah

2008-12-05

412

Reconstruction algorithm study of 2D interpolating resistive readout structure  

NASA Astrophysics Data System (ADS)

Systematic investigations including both simulation and prototype tests have been done about the interpolating resistive readout structure with GEM (Gaseous Electron Multiplier) detector. From the simulation, we have a good knowledge of the process of charge diffusion on the surface of the readout plane and develop several reconstruction methods to determine the hit position. The total signal duration time of a typical event with the readout structure was about several hundred nanoseconds, which implied an ideal count rate up to 106 Hz. A stable working prototype was designed and fabricated after the simulation. Using 55Fe 5.9 keV X-ray, the image performance of the prototype was examined with flat field image and some special geometry shapes, meanwhile, an energy resolution of about 17% was obtained.

Xiu, Qing-Lei; Dong, Ming-Yi; Liu, Rong-Guang; Zhang, Jian; Ouyang, Qun; Chen, Yuan-Bo

2013-10-01

413

Non-rigid 2D-3D Medical Image Registration using Markov Random Fields  

E-print Network

Non-rigid 2D-3D Medical Image Registration using Markov Random Fields Enzo Ferrante and Nikos of this approach. Keywords: 2D-3D registration, medical imaging, markov random fields, dis- crete optimization. 1 Introduction 2D-3D image registration is an important problem in medical imaging and it can be applied

414

ESSDERC, Bucharest, Sep. 19, 2013.Kaustav Banerjee, UCSB 2D Electronics: Graphene and Beyond  

E-print Network

Nanomaterials Graphene (Thinnest 2D Crystal) Single-wall CNT (1D) Multi-wall CNT (1D) Graphene (Thinnest 2D Crystal) Monolayer Graphene NanoRibbons (GNRs) (1D) zigzag armchair Multi-layer GNR (1D) #12;ESSDERCESSDERC, Bucharest, Sep. 19, 2013.Kaustav Banerjee, UCSB 2D Electronics: Graphene and Beyond

Liebling, Michael

415

Assigning molecules with 2D-NMR: Static and dynamic aspects Franoise Sauriol  

E-print Network

Assigning molecules with 2D-NMR: Static and dynamic aspects Fran�oise Sauriol e-mail : francoise.sauriol@chem.queensu.ca Chemistry Department, Queen's University https://qshare.queensu.ca/Users01/sauriolf/www/ 2D-NMR techniques at the characterization of molecules that undergo dynamic motion. A special attention will be placed on explaining how 2D

Graham, Nick

416

Communication HyperSPASM NMR: A new approach to single-shot 2D correlations  

E-print Network

Communication HyperSPASM NMR: A new approach to single-shot 2D correlations on DNP-enhanced samples Available online 29 October 2012 Keywords: 2D NMR Dissolution DNP Hyperpolarization Heteronuclear connectivity, two-dimensional (2D) NMR conveys unique information about a molecule's struc- ture and dynamics

Frydman, Lucio

417

Real-Time 2D NMR Identification of Analytes Undergoing Continuous Chromatographic Separation  

E-print Network

Real-Time 2D NMR Identification of Analytes Undergoing Continuous Chromatographic Separation Boaz, with the real-time acquisition of a series of 2D 1 H NMR spectra arising from a mixture of compounds subject to a continuous liquid chromatography (LC) separation. This real-time 2D NMR identification of chemicals eluted

Frydman, Lucio

418

Single-scan 2D NMR spectroscopy on a 25 T bitter magnet Boaz Shapira a  

E-print Network

Single-scan 2D NMR spectroscopy on a 25 T bitter magnet Boaz Shapira a , Kiran Shetty b , William W Abstract 2D NMR relies on monitoring systematic changes in the phases incurred by spin coherences for 2D NMR acquisitions. It is here shown with a series of homo- and hetero-nuclear examples

Frydman, Lucio

419

Ultrafast Solid-State 2D NMR Experiments via Orientational Encoding Rangeet Bhattacharyya and Lucio Frydman*  

E-print Network

Ultrafast Solid-State 2D NMR Experiments via Orientational Encoding Rangeet Bhattacharyya and Lucio October 6, 2006; E-mail: lucio.frydman@weizmann.ac.il 2D NMR1 enables the characterization of a wide by sensitivity constraints. Proposals for accelerating 2D NMR include among others non-FT schemes3 as well

Frydman, Lucio

420

Communication Single-scan 2D NMR correlations by multiple coherence transfers  

E-print Network

Communication Single-scan 2D NMR correlations by multiple coherence transfers Maayan Gal 1 , Lucio: Multidimensional spectroscopy Ultrafast 2D NMR HSQC Coherence transfer processes a b s t r a c t A new scheme for the acquisition of heteronuclear 2D correlations in NMR spectroscopy within a single scan, is proposed

Frydman, Lucio

421

Sorting out Mixtures with 2D NMR Gregory S. Boebinger, National High Magnetic Field Laboratory  

E-print Network

Sorting out Mixtures with 2D NMR Gregory S. Boebinger, National High Magnetic Field Laboratory DMR-Award 0654118 AMRIS Facility We developed a 2D NMR peak alignment algorithm that enables pattern recognition of the resonances. The combination of 2D NMR spectra with full-resolution statistical analysis provides a platform

Weston, Ken

422

Quadrupolar and Chemical Shift Tensors Characterized by 2D Multiple-Quantum NMR Spectroscopy  

E-print Network

Quadrupolar and Chemical Shift Tensors Characterized by 2D Multiple-Quantum NMR Spectroscopy Ales The present work discusses a new 2D NMR method for char- acterizing the principal values and relative; multiple-quantum spectroscopy; 2D NMR correlations. 1. INTRODUCTION Quadrupolar nuclei with half

Frydman, Lucio

423

Real-Time Monitoring of Chemical Transformations by Ultrafast 2D NMR Spectroscopy  

E-print Network

Real-Time Monitoring of Chemical Transformations by Ultrafast 2D NMR Spectroscopy Maayan Gal, Mor: An approach enabling the acquisition of 2D nuclear magnetic resonance (NMR) spectra within a single scan has of these measurements involved acquiring a train of 2D 1 H-15 N HSQC NMR spectra separated by ca. 4 s; following

Frydman, Lucio

424

Symmetric spatial encoding in ultrafast 2D NMR spectroscopy Boaz Shapira, Yoav Shrot, Lucio Frydman *  

E-print Network

Symmetric spatial encoding in ultrafast 2D NMR spectroscopy Boaz Shapira, Yoav Shrot, Lucio Frydman with a series of amplitude-modulated homo- and hetero-nuclear 2D ultrafast NMR examples. ? 2005 Elsevier Inc. All rights reserved. Keywords: Ultrafast 2D NMR; Spatial encoding; Double-frequency-sweep irradiation

Frydman, Lucio

425

Bicomponent blend-directed amplification of the alkyl chain effect on the 2D structures.  

PubMed

Only one methylene unit difference in the long alkyl group of isobutenyl ether compounds is amplified by blending, resulting in the diversification of 2D structures, although each component formed individual 2D patterns, regardless of alkyl chain lengths. The 2D structures were revealed by using scanning tunneling microscopy at the solid/liquid interface. PMID:25229070

Kikkawa, Yoshihiro; Ishitsuka, Manami; Kashiwada, Ayumi; Tsuzuki, Seiji; Hiratani, Kazuhisa

2014-10-01

426

Structural noise and coherent backscattering modelled with the ATHENA 2D finite elements code  

E-print Network

Structural noise and coherent backscattering modelled with the ATHENA 2D finite elements code S in complex media has to be validated. In this study, the finite element code ATHENA 2D developed by EDF R numerically. The finite elements code Athena 2D has been developed by an EDF R&D­INRIA collaboration

Paris-Sud XI, Université de

427

T2D@ZJU: a knowledgebase integrating heterogeneous connections associated with type 2 diabetes mellitus.  

PubMed

Type 2 diabetes mellitus (T2D), affecting >90% of the diabetic patients, is one of the major threats to human health. A comprehensive understanding of the mechanisms of T2D at molecular level is essential to facilitate the related translational research. Here, we introduce a comprehensive and up-to-date knowledgebase for T2D, i.e. T2D@ZJU. T2D@ZJU contains three levels of heterogeneous connections associated with T2D, which is retrieved from pathway databases, protein-protein interaction databases and literature, respectively. In current release, T2D@ZJU contains 1078 T2D related entities such as proteins, protein complexes, drugs and others together with their corresponding relationships, which include 3069 manually curated connections, 14,893 protein-protein interactions and 26,716 relationships identified by text-mining technology. Moreover, T2D@ZJU provides a user-friendly web interface for users to browse and search data. A Cytoscape Web-based interactive network browser is available to visualize the corresponding network relationships between T2D-related entities. The functionality of T2D@ZJU is shown by means of several case studies. Database URL: http://tcm.zju.edu.cn/t2d. PMID:23846596

Yang, Zhenzhong; Yang, Jihong; Liu, Wei; Wu, Leihong; Xing, Li; Wang, Yi; Fan, Xiaohui; Cheng, Yiyu

2013-01-01

428

Substrate binding and protein conformational dynamics measured by 2D-IR vibrational  

E-print Network

Substrate binding and protein conformational dynamics measured by 2D-IR vibrational echo of small organic molecule substrates is studied by using 2D-IR vibrational echo spectroscopy. Carbon? Ultrafast 2D-IR vibrational echo spectroscopy can probe protein conformational fluctuations under thermal

Fayer, Michael D.

429

Quantum geometry and gravitational entropy  

SciTech Connect

Most quantum states have wavefunctions that are widely spread over the accessible Hilbert space and hence do not have a good description in terms of a single classical geometry. In order to understand when geometric descriptions are possible, we exploit the AdS/CFT correspondence in the half-BPS sector of asymptotically AdS_5 x S5 universes. In this sector we devise a"coarse-grained metric operator" whose eigenstates are well described by a single spacetime topology and geometry. We show that such half-BPS universes have a non-vanishing entropy if and only if the metric is singular, and that the entropy arises from coarse-graining the geometry. Finally, we use our entropy formula to find the most entropic spacetimes with fixed asymptotic moments beyond the global charges.

Simon, Joan; Balasubramanian, Vijay; Czech, Bart Iomiej; Larjo, Klaus; Marolf, Donald; Simon, Joan

2007-05-29

430

Photorealistic image synthesis and camera validation from 2D images  

NASA Astrophysics Data System (ADS)

This paper presents a new 3D scene reconstruction technique using the Unity 3D game engine. The method presented here allow us to reconstruct the shape of simple objects and more complex ones from multiple 2D images, including infrared and digital images from indoor scenes and only digital images from outdoor scenes and then add the reconstructed object to the simulated scene created in Unity 3D, these scenes are then validated with real world scenes. The method used different cameras settings and explores different properties in the reconstructions of the scenes including light, color, texture, shapes and different views. To achieve the highest possible resolution, it was necessary the extraction of partial textures from visible surfaces. To recover the 3D shapes and the depth of simple objects that can be represented by the geometric bodies, there geometric characteristics were used. To estimate the depth of more complex objects the triangulation method was used, for this the intrinsic and extrinsic parameters were calculated using geometric camera calibration. To implement the methods mentioned above the Matlab tool was used. The technique presented here also let's us to simulate small simple videos, by reconstructing a sequence of multiple scenes of the video separated by small margins of time. To measure the quality of the reconstructed images and video scenes the Fast Low Band Model (FLBM) metric from the Video Quality Measurement (VQM) software was used. Low bandwidth perception based features include edges and motion.

Santos Ferrer, Juan C.; Gonzlez Chvere, David; Manian, Vidya

2014-06-01

431

Fabrication of 2D arrays of multi-component nanoparticles  

NASA Astrophysics Data System (ADS)

The paper presents a study of a physical method for fabrication of two-dimensional (2D) arrays composed of multi-component nanoparticles on a dielectric substrate. The method consists of two steps. In the first one, thin films composed of different metals are deposited by a classical PLD technique by using targets consisting of sections of different materials. Thin films composed of mixtures of different metals, as gold, silver, nickel, cobalt, iron, platinum, are thus deposited on a quartz substrate. By changing the area of the different sections in the target, thin films with different concentration of the metals are produced. The films fabricated are then annealed by nanosecond laser pulses delivered by a Nd:YAG laser system operating at its third harmonic. The modification of the films is studied as a function of the parameters of the incident radiation, as number of pulses and laser pulse fluence. It is found that the laser annealing can lead to a decomposition of the film into a monolayer of nanoparticles with a narrow size distribution. The optical properties of the structures produced are analyzed on the basis of their transmission spectra. The structures can be used in surface enhanced Raman spectroscopy (SERS) and magneto-optics.

Nikov, Ru G.; Nedyalkov, N. N.; Stankova, N. E.; Atanasov, P. A.

2014-05-01

432

2D/3D registration algorithm for lung brachytherapy  

SciTech Connect

Purpose: A 2D/3D registration algorithm is proposed for registering orthogonal x-ray images with a diagnostic CT volume for high dose rate (HDR) lung brachytherapy. Methods: The algorithm utilizes a rigid registration model based on a pixel/voxel intensity matching approach. To achieve accurate registration, a robust similarity measure combining normalized mutual information, image gradient, and intensity difference was developed. The algorithm was validated using a simple body and anthropomorphic phantoms. Transfer catheters were placed inside the phantoms to simulate the unique image features observed during treatment. The algorithm sensitivity to various degrees of initial misregistration and to the presence of foreign objects, such as ECG leads, was evaluated. Results: The mean registration error was 2.2 and 1.9 mm for the simple body and anthropomorphic phantoms, respectively. The error was comparable to the interoperator catheter digitization error of 1.6 mm. Preliminary analysis of data acquired from four patients indicated a mean registration error of 4.2 mm. Conclusions: Results obtained using the proposed algorithm are clinically acceptable especially considering the complications normally encountered when imaging during lung HDR brachytherapy.

Zvonarev, P. S. [McMaster University, Medical Physics and Applied Radiation Sciences, Hamilton, Ontario L8S 4L8 (Canada); Farrell, T. J.; Hunter, R.; Wierzbicki, M.; Hayward, J. E. [McMaster University, Medical Physics and Applied Radiation Sciences, Hamilton, Ontario L8S 4L8 (Canada); Juravinski Cancer Centre, Medical Physics, Hamilton, Ontario L8V 5C2 (Canada); Sur, R. K. [McMaster University, Medical Physics and Applied Radiation Sciences, Hamilton, Ontario L8S 4L8 (Canada); Juravinski Cancer Centre, Radiation Oncology, Hamilton, Ontario L8V 5C2 (Canada)

2013-02-15

433

2D luminescence imaging of physiological wound oxygenation.  

PubMed

In cutaneous wound healing, the role of oxygen in vivo is poorly understood. We studied wound surface pO(2) during physiological wound healing in humans. Split-thickness skin graft donor sites (n=12) served as standardized wound models. Wound surface pO(2) was measured at 1, 6 and 14days after split-skin harvesting using two-dimensional luminescence lifetime imaging (2D-LLI) of palladium(II)-meso-tetraphenyl-tetrabenzoporphyrin (Pd-TPTBP) in polystyrene-co-acrylonitrile (PSAN) particles on transparent foils. In another experiment, we removed the stratum corneum (SC) on the volar forearm (n=10) by tape strippings to study the impact of the SC on the epidermal oxygen barrier. Split-skin donor site pO(2) significantly decreased during the time course of physiological healing. Regional differences in pO(2) within donor site wounds were visualized for the first time in literature. No difference was found in pO(2) before and after SC removal, showing that the SC is not a major constituent of the epidermal oxygen barrier. PMID:21443617

Schreml, Stephan; Meier, Robert J; Wolfbeis, Otto S; Maisch, Tim; Szeimies, Rolf-Markus; Landthaler, Michael; Regensburger, Johannes; Santarelli, Francesco; Klimant, Ingo; Babilas, Philipp

2011-07-01

434

Parallel streamline placement for 2D flow fields.  

PubMed

Parallel streamline placement is still an open problem in flow visualization. In this paper, we propose an innovative method to place streamlines in parallel for 2D flow fields. This method is based on our proposed concept of local tracing areas (LTAs). An LTA is defined as a subdomain enclosed by streamlines and/or field borders, where the tracing of streamlines are localized. Given a flow field, it is initialized as an LTA, which is later recursively partitioned into hierarchical LTAs. Streamlines are placed within different LTAs simultaneously and independently. At the same time, to control the density of streamlines, each streamline is associated with an isolation zone and a saturation zone, both of which are center aligned with the streamline but have different widths. None of streamlines can trace into isolation zones of others. And new streamlines are only seeded within valid seeding areas (VSAs) that are enclosed by saturation zones and/or field borders. To implement the parallel strategy and the density control, a cell-based modeling is devised to describe isolation zones and LTAs as well as saturation zones and VSAs. With the help of these cell-based models, a heuristic seeding strategy is proposed to seed streamlines within irregular LTAs, and a cell-marking technique is used to control the seeding and tracing of streamlines. Test results show that the placement method can achieve highly parallel performance on shared memory systems without losing the quality of placements. PMID:22889829

Zhang, Wenyao; Wang, Yi; Zhan, Jianfeng; Liu, Beichen; Ning, Jianguo

2013-07-01

435

Antenna coupled detectors for 2D staring focal plane arrays  

NASA Astrophysics Data System (ADS)

Millimeter-wave (mmW)/sub-mmW/THz region of the electro-magnetic spectrum enables imaging thru clothing and other obscurants such as fog, clouds, smoke, sand, and dust. Therefore considerable interest exists in developing low cost millimeter-wave imaging (MMWI) systems. Previous MMWI systems have evolved from crude mechanically scanned, single element receiver systems into very complex multiple receiver camera systems. Initial systems required many expensive mmW integrated-circuit low-noise amplifiers. In order to reduce the cost and complexity of the existing systems, attempts have been made to develop new mmW imaging sensors employing direct detection arrays. In this paper, we report on Raytheon's recent development of a unique focal plane array technology, which operates broadly from the mmW through the sub-mmW/THz region. Raytheon's innovative nano-antenna based detector enables low cost production of 2D staring mmW focal plane arrays (mmW FPA), which not only have equivalent sensitivity and performance to existing MMWI systems, but require no mechanical scanning.

Gritz, Michael A.; Kolasa, Borys; Lail, Brian; Burkholder, Robert; Chen, Leonard

2013-06-01

436

Anatomy of luminosity functions: the 2dFGRS example  

E-print Network

Aims. We use the 2dF Galaxy Redshift Survey to derive the luminosity function (LF) of the first-ranked (brightest) group/cluster galaxies, the LF of second-ranked, satellite and isolated galaxies, and the LF of groups of galaxies. Methods. We investigate the LFs of different samples in various environments: in voids, filaments, superclusters and supercluster cores. We compare the derived LFs with the Schechter and double-power-law analytical expressions. We also analyze the luminosities of isolated galaxies. Results. We find strong environmental dependency of luminosity functions of all populations. The luminosities of first-ranked galaxies have a lower limit, depending on the global environment (higher in supercluster cores, and absent in voids). The LF of second-ranked galaxies in high-density regions is similar to the LF of first-ranked galaxies in a lower-density environment. The brightest isolated galaxies can be identified with first-ranked galaxies at distances where the remaining galaxies lie outside the observational window used in the survey. Conclusions. The galaxy and cluster LFs can be well approximated by a double-power-law; the widely used Schechter function does not describe well the bright end and the bend of the LFs. Properties of the LFs reflect differences in the evolution of galaxies and their groups in different environments.

Elmo Tempel; Jaan Einasto; Maret Einasto; Enn Saar; Erik Tago

2008-05-28

437

Global 2-D intercomparison of sectional and modal aerosol modules  

SciTech Connect

We present an intercomparison of two aerosol modules, one sectional, one modal, in a global 2-D model in order to differentiate their behavior for tropospheric and stratospheric applications. We model only binary sulfuric acid-water aerosols in this study. Two versions of the sec-tional model and three versions of the modal model are used to test the sensitivity of background aerosol mass and size distribution to the number of bins or modes and to the pre-scribed width of the largest mode. We ?nd modest sensitivity to the number of bins (40 vs 150) used in the sectional model. Aerosol mass is found to be reduced in a modal model if care is not taken in selecting the width of the largest lognormal mode, re?ecting differences in sedimentation in the middle stratosphere. The size distributions calculated by the sec-tional model can be better matched by a modal model with four modes rather than three modes in most but not all sit-uations. A simulation of aerosol decay following the 1991 eruption of Mt. Pinatubo shows that the representation of the size distribution can have a sign?cant impact on model-calculated aerosol decay rates in the stratosphere. Between 1991 and 1995, aerosol mass and surface area density calcu-lated by two versions of the modal model adequately match results from the sectional model. Calculated effective radius for the same time period shows more intermodel variability.

Weisenstein, D. K.; Penner, J. E.; Herzog, M.; Liu, Xiaohong

2007-05-08

438

Damage mechanics in 2-D and 3-D microstructures  

NASA Astrophysics Data System (ADS)

The evolution of damage and strategies for assessing damage when it has occurred in structural materials is the primary focus of this research program. The research effort is a collaborative one on mesomechanics called 'Damage in 2D and 3D Microstructures.' What distinguishes this effort from others is the attempt to perform incisive model experiments to assist in evaluating stochastic models for constitutive laws (elasticity and conductivity), mechanical response plasticity, and hardness and associated damage processes. The theoretical models are designed to be elegant and efficient in the use of computing resources as opposed to brute force procedures which handle systems with different scales by scaling up the size of the computer. The essence of this work is to explore sample size microstructure relationships via stochastic models which reflect the same types of variability present in the response of real materials. This leads directly to concerns with effective properties of materials. Thus, research integrates the effects of microstructure and preferred orientation on the effective tensorial properties of polycrystalline materials.

Bowman, Keith J.; Ostoja-Starzewski, Martin

1993-02-01

439

Non-universality in the 2D flocking model  

NASA Astrophysics Data System (ADS)

In this paper, we discuss the universality of the critical exponents ? and ? found in the Viscek model for one zone of interaction in the 2D flocking model. Within the framework of this model, the particles move with the same absolute velocity v0 and interact locally by trying to align their direction with that of neighbors. In this paper, we include a second zone of interaction named zone of repulsion R1, where each agent attempts to maintain a minimum distance from the others. Our model results show that in order to maintain an order in a flock with higher density, it is necessary to decrease the region of repulsion around each individual. Depending on the noise and on the density, the order parameter va is found to scale as ( (? c - ? )/(? c))? and ((? - ? c)/(?_c ))? , respectively. Our findings show that the exponents ? and ? depend strongly on the size of the repulsion zone and on the density ?, indicating the non-universality of these critical exponents. The analysis is performed over different situations by using a numerical simulation technique.

Tarras, I.; Mazroui, M.; Moussa, N.; Boughaleb, Y.

2014-06-01

440

2D Fokker-Planck models of rotating clusters  

NASA Astrophysics Data System (ADS)

Globular clusters rotate significantly, and with the increasing amount of detailed morphological and kinematical data obtained in recent years on galactic globular clusters many interesting features show up. We show how our theoretical evolutionary models of rotating clusters can be used to obtain fits, which at least properly model the overall rotation and its implied kinematics in full 2D detail (dispersions, rotation velocities). Our simplified equal mass axisymmetric rotating model provides detailed two-dimensional kinematical and morphological data for star clusters. The degree of rotation is not dominant in energy, but also non-negligible for the phase-space distribution function, shape and kinematics of clusters. Therefore, the models are well applicable for galactic globular clusters. Since previously published papers on that matter by us made it difficult to do detailed comparisons with observations, we provide a much more comprehensive and easy-to-use set of data here, which uses as entries dynamical age and flattening of observed cluster and then offers a limited range of applicable models in full detail. The method, data structure and some exemplary comparison with observations are presented. Future work will improve modelling and data base to take a central black hole, a mass spectrum and stellar evolution into account.

Fiestas, J.; Spurzem, R.; Kim, E.

2006-12-01

441

2D modeling of electromagnetic waves in cold plasmas  

NASA Astrophysics Data System (ADS)

The consequences of sheath (rectified) electric fields, resulting from the different mobility of electrons and ions as a response to radio frequency (RF) fields, are a concern for RF antenna design as it can cause damage to antenna parts, limiters and other in-vessel components. As a first step to a more complete description, the usual cold plasma dielectric description has been adopted, and the density profile was assumed to be known as input. Ultimately, the relevant equations describing the wave-particle interaction both on the fast and slow timescale will need to be tackled but prior to doing so was felt as a necessity to get a feeling of the wave dynamics involved. Maxwell's equations are solved for a cold plasma in a 2D antenna box with strongly varying density profiles crossing also lower hybrid and ion-ion hybrid resonance layers. Numerical modelling quickly becomes demanding on computer power, since a fine grid spacing is required to capture the small wavelengths effects of strongly evanescent modes.

Cromb, K.; Van Eester, D.; Koch, R.; Kyrytsya, V.

2014-02-01

442

Design of wheel motor using Maxwell 2D simulation  

SciTech Connect

This paper presents a high efficiency direct wheel motor drive for electric vehicles (EVs). The proposed motor is a permanent magnet square-wave motor whose rotor with rare earth magnets forms the outside of the motor to be set within each rear wheel tire to realize the direct drive. The inner stator with its windings is rigidly linked to the suspension and frame structure of the vehicle. In order to achieve the direct drive without any mechanical transmission for EVs, the wheel motor has been designed as a low-speed high-torque motor. The design and optimization of the motor was done with the aid of finite element electromagnetic field analysis using the Maxwell 2D Simulator software. The motor parameters and characteristics can be accurately calculated and predicted in terms of field computation and analysis results. The design procedure of the 6.6 kW, 1,000 rpm wheel motor and its technical data are given in this paper.

Chen, G.H.; Tseng, K.J. [Nanyang Technological Univ., Singapore (Singapore). School of Electrical and Electronic Engineering

1995-12-31

443

2D Toda ?-functions as combinatorial generating functions  

E-print Network

Two methods of constructing 2D Toda $\\tau$-functions that are generating functions for certain geometrical invariants of a combinatorial nature are related. The first involves generation of paths in the Cayley graph of the symmetric group $S_n$ by multiplication of the conjugacy class sums $C_\\lambda \\in C[S_n]$ in the group algebra by elements of an abelian group of central elements. Extending the characteristic map to the tensor product $C[S_n]\\otimes C[S_n]$ leads to double expansions in terms of power sum symmetric functions, in which the coefficients count the number of such paths. Applying the same map to sums over the orthogonal idempotents leads to diagonal double Schur function expansions that are identified as $\\tau$-functions of hypergeometric type. The second method is the standard construction of $\\tau$-functions as vacuum state matrix elements of products of vertex operators in a fermionic Fock space with elements of the abelian group of convolution symmetries. A homomorphism between these two group actions is derived and shown to be intertwined by the characteristic map composed with fermionization. Applications include Okounkov's generating function for double Hurwitz numbers, which count branched coverings of the Riemann sphere with nonminimal branching at two points, and various analogous combinatorial counting functions.

Mathieu Guay-Paquet; J. Harnad

2014-05-24

444

2D Toda \\tau-functions as combinatorial generating functions  

E-print Network

Two methods of constructing 2D Toda $\\tau$-functions that are generating functions for certain geometrical invariants of a combinatorial nature are related. The first involves generation of paths in the Cayley graph of the symmetric group $S_n$ by multiplication of the conjugacy class sums $C_\\lambda \\in C[S_n]$ in the group algebra by elements of an abelian group of central elements. Extending the characteristic map to the tensor product $C[S_n]\\otimes C[S_n]$ leads to double expansions in terms of power sum symmetric functions, in which the coefficients count the number of such paths. Applying the same map to sums over the orthogonal idempotents leads to diagonal double Schur function expansions that are identified as $\\tau$-functions of hypergeometric type. The second method is the standard construction of $\\tau$-functions as vacuum state matrix elements of products of vertex operators in a fermionic Fock space with elements of the abelian group of convolution symmetries. A homomorphism between these two g...

Guay-Paquet, Mathieu

2014-01-01

445

Fast visible 2-D camera imaging on NSTX  

NASA Astrophysics Data System (ADS)

Initial applications of 2-D cameras on tokamak devices were mainly used to gain qualitative insight into global dynamics such as plasma formation and motion. Quantitative data were limited, due in large part to the time scales of most plasma events that were far faster than the frame rate of the camera and the inability to resolve structures at the characteristic plasma scale lengths. Recent advances in the development of fast cameras increased the frame rate up to megahertz rates while exposure times as short as 3nsec have been achieved with intensifiers. NSTX supports 8 fast visible cameras with framing rates ranging from 10^3 to 10^6 frames/sec with resolution from 64 X 64 to 1024 X 1080 pixels at the shortest exposure times. These cameras have been used to study plasma phenomena including edge and divertor turbulence, ELMs, and impurity transport. The most recent applications include studies of supersonic gas jets, pellet ablation, incandescent dust behavior, and measurement of fast ion loss of neutral beam injected particles. The capabilities of each camera will be presented and movies of plasma phenomena recorded with them will be presented.

Roquemore, A. L.; Nishino, N.; Maqueda, R.; Bush, C.; Dorf, L.; Shinohara, K.

2005-10-01

446

Stray-light correction in 2D spectroscopy  

NASA Astrophysics Data System (ADS)

Context. In solar physics, spectropolarimeters based on Fabry-Prot interferometers are commonly used for high spatial resolution observations. In the data pipeline, corrections for scattered light may be performed on each narrow band image. Aims: We elaborate on the effects of stray-light corrections on Doppler maps. Methods: First, we demonstrate the basic correction effect in a simplified situation of two profiles that suffer from stray light. Then, we study the correction effects on velocity maps by transforming a Hinode SP map into a two-dimensional spectroscopic data set with i(x,y) at each wavelength point, which mimicks narrow band images. Velocity maps are inferred from line profiles of original and stray-light corrected data. Results: The correction of scattered light in narrow band images affects the inferred Doppler velocity maps: relative red shifts always become more red, and relative blue shifts become more blue. This trend is independent of whether downflows have dark or bright intensities. As a result, the effects of overcorrection produce both downflows and upflows. Conclusions: In 2D spectropolarimetry, corrections for scattered light can improve the image intensity and velocity contrast but inherently produce downflow signatures in the penumbra. Hence, such corrections are justified only if the properties of the stray light (seeing, telescope, and instrument) are well known.

Schlichenmaier, R.; Franz, M.

2013-07-01

447

Color constancy in 3D-2D face recognition  

NASA Astrophysics Data System (ADS)

Face is one of the most popular biometric modalities. However, up to now, color is rarely actively used in face recognition. Yet, it is well-known that when a person recognizes a face, color cues can become as important as shape, especially when combined with the ability of people to identify the color of objects independent of illuminant color variations. In this paper, we examine the feasibility and effect of explicitly embedding illuminant color information in face recognition systems. We empirically examine the theoretical maximum gain of including known illuminant color to a 3D-2D face recognition system. We also investigate the impact of using computational color constancy methods for estimating the illuminant color, which is then incorporated into the face recognition framework. Our experiments show that under close-to-ideal illumination estimates, one can improve face recognition rates by 16%. When the illuminant color is algorithmically estimated, the improvement is approximately 5%. These results suggest that color constancy has a positive impact on face recognition, but the accuracy of the illuminant color estimate has a considerable effect on its benefits.

Meyer, Manuel; Riess, Christian; Angelopoulou, Elli; Evangelopoulos, Georgios; Kakadiaris, Ioannis A.

2013-05-01

448

2-D Collision of Pucks -- Center of Mass Velocity  

NSDL National Science Digital Library

This lab uses Tracker video analysis software to measure and analyze the center of mass of a system of two pucks during a two-dimensional collision. Students measure the initial and final velocity vector for each puck and calculate the center-of-mass velocity of the system before and after the collision and show that it is constant. Tracker can automatically calculate and mark the center of mass in each frame, so it is easy to see that the center of mass velocity is constant and calculate its value from graphs of center-of-mass variables. The zip file contains the lab handout, a video showing a 2-D collision of pucks, and the Tracker file. The video copyright is Flashmedia. To open the Tracker file, download and run