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1

Extension of RAPTOR-M3G to r-?-z Geometry for Use in Reactor Dosimetry Applications  

NASA Astrophysics Data System (ADS)

The RAPTOR-M3G (RApid Parallel Transport Of Radiation - Multiple 3-D Geometries) is a new deterministic radiation transport code that was originally developed for x-y-z geometry. The development of the r-?-z version of RAPTOR-M3G and its application to determine ex-vessel neutron dosimetry responses in the cavity of a typical 2-loop pressurized water reactor is presented. The neutron dosimetry responses determined from RAPTOR-M3G and TORT 3-D r-?-z calculations are compared to actual measured responses.

Hunter, Melissa A.; Longoni, Gianluca; Anderson, Stanwood L.

2009-08-01

2

Transport Equation Solution by the Even Parity Method. Numerical Study of the Transport Evolution Equation in Two-Dimensional Lagrangian Geometry R-Z.  

National Technical Information Service (NTIS)

To get rid of visible sides problems, while solving Boltzmann equation on Lagrangian mesh, an even parity equation has been developed in 2D geometry. A conformous finite element method discretization is given by its week formulation and its mathematical r...

D. Verwaerde

1983-01-01

3

GBL-2D Version 1.0: a 2D geometry boolean library.  

SciTech Connect

This report describes version 1.0 of GBL-2D, a geometric Boolean library for 2D objects. The library is written in C++ and consists of a set of classes and routines. The classes primarily represent geometric data and relationships. Classes are provided for 2D points, lines, arcs, edge uses, loops, surfaces and mask sets. The routines contain algorithms for geometric Boolean operations and utility functions. Routines are provided that incorporate the Boolean operations: Union(OR), XOR, Intersection and Difference. A variety of additional analytical geometry routines and routines for importing and exporting the data in various file formats are also provided. The GBL-2D library was originally developed as a geometric modeling engine for use with a separate software tool, called SummitView [1], that manipulates the 2D mask sets created by designers of Micro-Electro-Mechanical Systems (MEMS). However, many other practical applications for this type of software can be envisioned because the need to perform 2D Boolean operations can arise in many contexts.

McBride, Cory L. (Elemental Technologies, American Fort, UT); Schmidt, Rodney Cannon; Yarberry, Victor R.; Meyers, Ray J. (Elemental Technologies, American Fort, UT)

2006-11-01

4

2-D Solar Dynamo Models in Spherical Geometry  

Microsoft Academic Search

We have developed a 2-D finite-difference code for solving the kinematic mean field dynamo equations in spherical geometry. We apply this code to the solar dynamo, considering interface dynamo models of the type initiated by Parker (1993, ApJ 408, 707) but including the full solar rotation profile as determined by helioseismology. The regeneration of the poloidal field by the alpha-effect

J. A. Markiel

1997-01-01

5

Transfer of polarized line radiation in 2D cylindrical geometry  

NASA Astrophysics Data System (ADS)

Aims: This paper deals with multidimensional NLTE polarized radiative transfer in the case of two level atom in the absence of lower level polarization. We aim to develop an efficient and robust method for 2D cylindrical geometry and to apply it to various axi-symmetrical astrophysical objects such as rings, disks, rotating stars, and solar prominences. Methods: We review the methods of short characteristics and Jacobi iteration applied to axisymmetric geometry. Then we demonstrate how to use a reduced basis for polarized intensity and polarized source function to self-consistently solve the coupled equations of radiative transfer and statistical equilibrium for linearly polarized radiation. We discuss some peculiarities that do not appear in Cartesian geometry, such as angular interpolation in performing the formal solution. We also show how to account for two different types of illuminating radiation. Results: The proposed method is tested on homogeneous, self-emitting cylinders to compare the results with those in 1D geometries. We demonstrate a possible astrophysical application on a very simple model of circumstellar ring illuminated by a host star where we show that such a disk can introduce a significant amount of scattering polarization in the system. Conclusions: This method is found to converge properly and, apparently, to allow for substantial time saving compared to 3D Cartesian geometry. We also discuss the advantages and disadvantages of this approach in multidimensional radiative transfer modeling.

Mili?, I.

2013-07-01

6

Collective motion of squirmers in a quasi-2D geometry  

NASA Astrophysics Data System (ADS)

Microorganisms like bacteria, algae or spermatozoa typically move in an aqueous environment where they interact via hydrodynamic flow fields. Recent experiments studied the collective motion of dense suspensions of bacteria where swarming and large-scale turbulence emerged. Moreover, spherical artificial microswimmers, so-called squirmers, have been constructed and studied in a quasi-2D geometry. Here we present a numerical study of the collective dynamics of squirmers confined in quasi-2D between two parallel walls. Because of their spherical shape the reorientation of squirmers is solely due to noise and hydrodynamic interactions via induced flow fields. This is in contrast to elongated swimmers like bacteria which locally align due to steric interactions. We study the collective motion of pushers, pullers and potential swimmers at different densities. At small densities the squirmers are oriented parallel to the walls and pairwise collisions determine the reorientation rate. In dense suspensions rotational diffusion is greatly enhanced and pushers, in particular, tend to orient perpendicular to the walls. This effects the dynamics of the emerging clusters. In very dense suspensions we observe active jamming and long-lived crystalline structures.

ZöTtl, Andreas; Stark, Holger

2013-03-01

7

2-D Solar Dynamo Models in Spherical Geometry  

NASA Astrophysics Data System (ADS)

We have developed a 2-D finite-difference code for solving the kinematic mean field dynamo equations in spherical geometry. We apply this code to the solar dynamo, considering interface dynamo models of the type initiated by Parker (1993, ApJ 408, 707) but including the full solar rotation profile as determined by helioseismology. The regeneration of the poloidal field by the alpha-effect occurs in the lower part of the convection zone, while the production of toroidal field by the differential rotation takes place below the convection zone. The surface rotation rate persists to the base of the convection zone, where a transition to rigid rotation of the core takes place within a thin layer of thickness <= 0.1 Rsun below the convection zone. The diffusivity changes discontinuously across the interface from its large turbulent value in the convection zone to a smaller uniform value in the core. Diffusivity ratios between 0.001 and 0.1 are considered. Both positive and negative alpha-effect are allowed, and the growth of the dynamo is limited by a nonlinear quenching of the alpha-effect based on the ratio of magnetic to kinetic energy density. If the shear layer is sufficiently thin so that the radial gradient of the rotation dominates the latitudinal gradient, then modes propagating along the interface are produced. The direction of propagation is towards the equator (pole) if the product alpha * partial Omega /partial r is negative (positive), as expected. However, the radial gradient changes sign at midlatitudes, which has two effects: (1) separate bands of field are produced in the equatorial and polar regions, propagating in different directions, and (2) the latitudinal gradient always dominates in the intermediate region where partial Omega /partial r ~ 0. The latter effect can produce different types of modes which alter or destroy the interface modes excited in the rest of the hemisphere. This research is supported by NSF grant AST-9528398.

Markiel, J. A.

1997-12-01

8

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

PubMed Central

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)10.1088/0031-9155/47/18/304] 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 Molière 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.; Mo, Xiaohu; Tome, Wolfgang A.; Mackie, Thomas R.; DeLuca, Paul M.

2013-01-01

9

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

10

Self-consistent, 2D simulations of filament propagation in photoconducting switches.  

National Technical Information Service (NTIS)

The authors present simulations of time-dependent filament propagation in laser-triggered GaAs photoswitches. Unlike previous modeling, the calculations are self-consistent in 2-D axisymmetric (r-z) geometry. Realistic electron and hole mobilities as well...

P. W. Rambo W. S. Lawson C. D. Capps R. A. Falk

1994-01-01

11

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

12

Single-Atom Trapping in Holographic 2D Arrays of Microtraps with Arbitrary Geometries  

NASA Astrophysics Data System (ADS)

We demonstrate single-atom trapping in two-dimensional arrays of microtraps with arbitrary geometries. We generate the arrays using a spatial light modulator, with which we imprint an appropriate phase pattern on an optical dipole-trap beam prior to focusing. We trap single Rb87 atoms in the sites of arrays containing up to approximately 100 microtraps separated by distances as small as 3 ?m, with complex structures such as triangular, honeycomb, or kagome lattices. Using a closed-loop optimization of the uniformity of the trap depths ensures that all trapping sites are equivalent. This versatile system opens appealing applications in quantum-information processing and quantum simulation, e.g., for simulating frustrated quantum magnetism using Rydberg atoms.

Nogrette, F.; Labuhn, H.; Ravets, S.; Barredo, D.; Béguin, L.; Vernier, A.; Lahaye, T.; Browaeys, A.

2014-04-01

13

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

PubMed

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

Aydemir, Erdo?an; Ulas, Abdullah

2011-02-15

14

Vectorization of a 2D-1D Iterative Algorithm for the 3D Neutron Transport Problem in Prismatic Geometries  

NASA Astrophysics Data System (ADS)

The past few years have been marked by a noticeable increase in the interest in 3D whole-core heterogeneous deterministic neutron transport solvers for reference calculations. Due to the extremely large problem sizes tackled by such solvers, they need to use adapted numerical methods and need to be efficiently implemented to take advantage of the full computing power of modern systems. As for numerical methods, one possible approach consists in iterating over resolutions of 2D and 1D MOC problems by taking advantage of prismatic geometries. The MICADO solver, developed at EDF R&D, is a parallel implementation of such a method in distributed and shared memory systems. However it is currently unable to use SIMD vectorization to leverage the full computing power of modern CPUs. In this paper, we describe our first effort to support vectorization in MICADO, typically targeting Intel© SSE CPUs. Both the 2D and 1D algorithms are vectorized, allowing for high expected speedups for the whole spatial solver. We present benchmark computations, which show nearly optimal speedups for our vectorized implementation on the TAKEDA case.

Moustafa, Salli; Févotte, François; Lathuilière, Bruno; Plagne, Laurent

2014-06-01

15

Detailed characterization of 2D and 3D scatter-to-primary ratios of various breast geometries using a dedicated CT mammotomography system  

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

16

A Simple 2-D Finite-Element Geometry for Analyzing Surface-Mounted Synchronous Machines With Skewed Rotor Magnets  

Microsoft Academic Search

We present a new 2-D FEM-based system for analyzing permanent-magnet surface-mounted synchronous machines with skewed rotor magnets. The system is based on generating a geometric equivalent non-skewed permanent-magnet distribution that accounts for the skewed distribution of the practical rotor. An appealing feature of the proposed system is that it can be easily performed in any 2-D electromagnetic FEM package by

Julio-César Urresty; J.-R. Riba Ruiz; Luís Romeral; Antonio Garcia

2010-01-01

17

Automated 2D NOESY Assignment and Structure Calculation of Crambin(S22\\/I25) with the Self-Correcting Distance Geometry Based NOAH\\/DIAMOD Programs  

Microsoft Academic Search

The NOAH\\/DIAMOD program suite was used to automatically assign an experimental 2D NOESY spectrum of the 46 residue protein crambin(S22\\/I25), using feedback filtering and self-correcting distance geometry (SECODG). Automatically picked NOESY cross peaks were combined with 157 manually assigned peaks to start NOAH\\/DIAMOD calculations. At each cycle, DIAMOD was used to calculate an ensemble of 40 structures from these NOE

Yuan Xu; Jian Wu; David Gorenstein; Werner Braun

1999-01-01

18

Constraining complex aquifer geometry with geophysics (2-D ERT and MRS measurements) for stochastic modelling of groundwater flow  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

19

MICADO: Parallel implementation of a 2D-1D iterative algorithm for the 3D neutron transport problem in prismatic geometries  

SciTech Connect

The large increase in computing power over the past few years now makes it possible to consider developing 3D full-core heterogeneous deterministic neutron transport solvers for reference calculations. Among all approaches presented in the literature, the method first introduced in [1] seems very promising. It consists in iterating over resolutions of 2D and ID MOC problems by taking advantage of prismatic geometries without introducing approximations of a low order operator such as diffusion. However, before developing a solver with all industrial options at EDF, several points needed to be clarified. In this work, we first prove the convergence of this iterative process, under some assumptions. We then present our high-performance, parallel implementation of this algorithm in the MICADO solver. Benchmarking the solver against the Takeda case shows that the 2D-1D coupling algorithm does not seem to affect the spatial convergence order of the MOC solver. As for performance issues, our study shows that even though the data distribution is suited to the 2D solver part, the efficiency of the ID part is sufficient to ensure a good parallel efficiency of the global algorithm. After this study, the main remaining difficulty implementation-wise is about the memory requirement of a vector used for initialization. An efficient acceleration operator will also need to be developed. (authors)

Fevotte, F.; Lathuiliere, B. [EDF R and D (France)] [EDF R and D (France)

2013-07-01

20

Weight functions and stress intensity factors for mode I cracks in arbitrary 2D geometries under general crack surface loading  

NASA Astrophysics Data System (ADS)

Stress intensity factors for mode I cracks in arbitrary two-dimensional geometries under general crack surface loading are derived in closed form by boundary element calculations and approximate weight functions. The boundary element method was developed previously to deal with arbitrary two-dimensional crack problems involving uniform crack surface pressure. Reference stress intensity factors calculated by the boundary element method are used to derive stress intensity factors for the same crack under arbitrary crack surface loading with weight functions based on an improved Petroski-Achenbach crack surface displacement approximation. Various crack problems are studied and limitations of the method are discussed. The investigation shows that a self-consistency examination will effectively reveal the accuracy of the derived weight functions and the associated stress intensity factors.

Wang, G. S.; Blom, A. F.

1993-01-01

21

Geometry  

NSDL National Science Digital Library

This collection, created by Salman Khan of the Khan Academy, features videos on geometry. A basic understanding of Algebra I necessary to understand the fundamental elements featured in this collection. Altogether, the site contains 23 videos the cover an array of topics under the field of geometry. After these lessons, you'll certainly be ready for Trigonometry.

Khan, Salman

2011-01-03

22

Computation of three-phase capillary entry pressures and arc menisci configurations in pore geometries from 2D rock images: A combinatorial approach  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

23

Available information in 2D motional Stark effect imaging.  

PubMed

Recent advances in imaging techniques have allowed the extension of the standard polarimetric 1D motional Stark effect (MSE) diagnostic to 2D imaging of the internal magnetic field of fusion devices [J. Howard, Plasma Phys. Controlled Fusion 50, 125003 (2008)]. This development is met with the challenge of identifying and extracting the new information, which can then be used to increase the accuracy of plasma equilibrium and current density profile determinations. This paper develops a 2D analysis of the projected MSE polarization orientation and Doppler phase shift. It is found that, for a standard viewing position, the 2D MSE imaging system captures sufficient information to allow imaging of the internal vertical magnetic field component B(Z)(r,z) in a tokamak. PMID:21033915

Creese, Mathew; Howard, John

2010-10-01

24

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

SciTech Connect

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

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

1991-02-22

25

2½D visual servoing  

Microsoft Academic Search

We propose an approach to vision-based robot control, called 2½D 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

26

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

27

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

28

Spinning geometry = Twisted geometry  

NASA Astrophysics Data System (ADS)

It is well known that the SU(2)-gauge invariant phase space of loop gravity can be represented in terms of twisted geometries. These are piecewise-linear-flat geometries obtained by gluing together polyhedra, but the resulting geometries are not continuous across the faces. Here we show that this phase space can also be represented by continuous, piecewise-flat three-geometries called spinning geometries. These are composed of metric-flat three-cells glued together consistently. The geometry of each cell and the manner in which they are glued is compatible with the choice of fluxes and holonomies. We first remark that the fluxes provide each edge with an angular momentum. By studying the piecewise-flat geometries which minimize edge lengths, we show that these angular momenta can be literally interpreted as the spin of the edges: the geometries of all edges are necessarily helices. We also show that the compatibility of the gluing maps with the holonomy data results in the same conclusion. This shows that a spinning geometry represents a way to glue together the three-cells of a twisted geometry to form a continuous geometry which represents a point in the loop gravity phase space.

Freidel, Laurent; Ziprick, Jonathan

2014-02-01

29

Lectures on 2D gravity and 2D string theory.  

National Technical Information Service (NTIS)

This report the following topics: loops and states in conformal field theory; brief review of the Liouville theory; 2D Euclidean quantum gravity I: path integral approach; 2D Euclidean quantum gravity II: canonical approach; states in 2D string theory; ma...

P. Ginsparg G. Moore

1992-01-01

30

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

31

Controlled Reagent Transport in Disposable 2D Paper Networks  

PubMed Central

Recent reports have demonstrated the multi-analyte detection capability of paper networks with multiple outlets per inlet. In this report, we focus on the capabilities of 2D paper networks with multiple inlets per outlet and demonstrate the controlled transport of reagents within paper devices. Specifically, we demonstrate methods of controlling fluid transport using the geometry of the network and dissovable barriers. Finally, we discuss the implications for higher sensitivity detection using this type of 2D paper network.

Fu, Elain; Lutz, Barry; Kauffman, Peter; Yager, Paul

2011-01-01

32

Shape Compression using Spherical Geometry Images  

Microsoft Academic Search

We recently introduced an algorithm for spherical parametrization and remeshing, which allows resampling of a genus-zero surface onto a regular 2D grid, a spherical geometry image. These geometry images offer several advantages for shape compression. First, simple extension rules extend the square image domain to cover the infinite plane, thereby providing a globally smooth surface parametrization. The 2D grid structure

Hugues Hoppe; Emil Praun

33

DYNA2D. Explicit 2-d Hydrodynamic FEM Program  

Microsoft Academic Search

DYNA2D is a vectorized, explicit, two dimensional, axisymmetric and plane strain finite element program for analyzing the large deformation dynamic and hydrodynamic response of inelastic solids. DYNA2D contains 13 material models and 9 equations of state (EOS) to cover a wide range of material behavior. The material models implemented in all machine versions are: elastic, orthotropic elastic, kinematic\\/isotropic elastic plasticity,

Whirley

1988-01-01

34

DYNA2D. Explicit 2-D Hydrodynamic FEM Program  

Microsoft Academic Search

DYNA2D is a vectorized, explicit, two-dimensional, axisymmetric and plane strain finite element program for analyzing the large deformation dynamic and hydrodynamic response of inelastic solids. DYNA2D contains 13 material models and 9 equations of state (EOS) to cover a wide range of material behavior. The material models implemented in all machine versions are: elastic, orthotropic elastic, kinematic\\/isotropic elastic plasticity, thermoelastoplastic,

Whirley

1988-01-01

35

Towards enumeration of crystalline frameworks: the 2D hyperbolic approach  

NASA Astrophysics Data System (ADS)

Crystalline frameworks in 3D Euclidean space can be constructed by projecting tilings of 2D hyperbolic space onto three-periodic minimal surfaces, giving surface reticulations. The technique involves Delaney-Dress tiling theory, group theory, differential and non-Euclidean geometry. Preliminary results of this approach, found at http://epinet.anu.edu.au, are discussed and compared with other approaches.

Hyde, S. T.; Delgado Friedrichs, O.; Ramsden, S. J.; Robins, V.

2006-07-01

36

Analysis of 2D triaxial flat braided textile composites  

Microsoft Academic Search

This paper is concerned with the development of an analytical model for the calculation of the effective linear elastic stiffness of a 2D triaxial flat braided composite (2DTBC) and the effect of initial unintended microstructural imperfections on the calculated stiffnesses. A representative unit cell (RUC) of the braid architecture is first identified along with its constituents. Tow geometry is represented

Shu Ching Quek; Anthony M. Waas; Khaled W. Shahwan; Venkatesh Agaram

2003-01-01

37

ISOGAT: A 2D tutorial MATLAB code for Isogeometric Analysis  

Microsoft Academic Search

A tutorial 2D MATLAB code for solving elliptic diffusion-type problems, including Poisson's equation on single patch geometries, is presented. The basic steps of Isogeometric Analysis are explained and two examples are given. The code has a very lean structure and has been kept as simple as possible, such that the analogy but also the differences to traditional finite element analysis

Anh-Vu Vuong; Christoph Heinrich; Bernd Simeon

2010-01-01

38

2D-Ising Model  

NSDL National Science Digital Library

The EJS 2D Ising model displays a lattice of spins. You can change the lattice size, temperature, and external magnetic field. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. The 2D-Ising model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_Ising2D.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2009-02-20

39

Extensions of 2D gravity  

SciTech Connect

After reviewing some aspects of gravity in two dimensions, I show that non-trivial embeddings of sl(2) in a semi-simple (super) Lie algebra give rise to a very large class of extensions of 2D gravity. The induced action is constructed as a gauged WZW model and an exact expression for the effective action is given.

Sevrin, A.

1993-06-01

40

Unparticle Example in 2D  

Microsoft Academic Search

We discuss what can be learned about unparticle physics by studying simple quantum field theories in one space and one time dimension. We argue that the exactly soluble 2D theory of a massless fermion coupled to a massive vector boson, the Sommerfield model, is an interesting analog of a Banks-Zaks model, approaching a free theory at high energies and a

Howard Georgi; Yevgeny Kats

2008-01-01

41

The relation between Euclidean and Lorentzian 2D quantum gravity  

NASA Astrophysics Data System (ADS)

Starting from 2D Euclidean quantum gravity, we show that one recovers 2D Lorentzian quantum gravity by removing all baby universes. Using a peeling procedure to decompose the discrete, triangulated geometries along a one-dimensional path, we explicitly associate with each Euclidean space-time a (generalized) Lorentzian space-time. This motivates a map between the parameter spaces of the two theories, under which their propagators get identified. In two dimensions, Lorentzian quantum gravity can therefore be viewed as a ``renormalized'' version of Euclidean quantum gravity.

Ambjørn, J.; Correia, J.; Kristjansen, C.; Loll, R.

2000-02-01

42

Synthesis and structural transformations of colloidal 2D layered metal chalcogenide nanocrystals.  

PubMed

This review presents recent advances in synthetic methods and structural transformations of colloidal 2D layered metal chalcogenide nanocrystals. Planar 2D anisotropy and interlayer van der Waals gaps are the important characteristics of these nanocrystals for pristine disc, plate or sheet morphologies. These 2D nanocrystals undergo unique chemical transformations upon exposure to external chemical stimuli and newly obtained structures are 2D nanostructures with high complexity in their morphological geometries and chemical compositions. Finally, future opportunities and potential applications of 2D layered metal chalcogenide nanocrystals are briefly discussed. PMID:23212120

Han, Jae Hyo; Lee, Sujeong; Cheon, Jinwoo

2013-04-01

43

DYNA2D. Explicit 2-D Hydrodynamic FEM Program  

SciTech Connect

DYNA2D is a vectorized, explicit, two-dimensional, axisymmetric and plane strain finite element program for analyzing the large deformation dynamic and hydrodynamic response of inelastic solids. DYNA2D contains 13 material models and 9 equations of state (EOS) to cover a wide range of material behavior. The material models implemented in all machine versions are: elastic, orthotropic elastic, kinematic/isotropic elastic plasticity, thermoelastoplastic, soil and crushable foam, linear viscoelastic, rubber, high explosive burn, isotropic elastic-plastic, temperature-dependent elastic-plastic. The additional models implemented in the CRAY and SUN machine versions are fluid, Johnson/Cook strain rate and temperature sensitive plasticity, and power law plasticity. The isotropic and temperature-dependent elastic-plastic models determine only the deviatoric stresses. Pressure is determined by one of 9 equations of state including linear polynomial, JWL high explosive, Sack `Tuesday` high explosive, Gruneisen, ratio of polynomials, linear polynomial with energy deposition, ignition and growth of reaction in HE, tabulated compaction, and tabulated.

Whirley, R.G. [Lawrence Livermore National Lab., CA (United States)

1988-03-01

44

DYNA2D. Explicit 2-d Hydrodynamic FEM Program  

SciTech Connect

DYNA2D is a vectorized, explicit, two dimensional, axisymmetric and plane strain finite element program for analyzing the large deformation dynamic and hydrodynamic response of inelastic solids. DYNA2D contains 13 material models and 9 equations of state (EOS) to cover a wide range of material behavior. The material models implemented in all machine versions are: elastic, orthotropic elastic, kinematic/isotropic elastic plasticity, thermoelastoplastic, soil and crushable foam, linear viscoelastic, rubber, high explosive burn, isotropic elastic plastic, and temperature dependent elastic-plastic. The additional models implemented in the CRAY and SUN machine versions are fluid, Johnson/Cook strain rate and temperature sensitive plasticity, and power law plasticity. The isotropic and temperature dependent elastic plastic models determine only the deviatoric stresses. Pressure is determined by one of 9 equations of state including linear polynomial, JWL high explosive, Sack `Tuesday` high explosive, Gruneisen, ratio of polynomials, linear polynomial with energy deposition, ignition and growth of reaction in HE, tabulated compaction, and tabulated.

Whirley, R.G. [Lawrence Livermore National Lab., CA (United States)

1988-03-01

45

2D Gauge Field Theory  

SciTech Connect

We show from the action integral that under the assumption of longitudinal dominance and transverse confinement, QCD4 in (3+1) dimensional space-time can be approximately compactified into QCD2 in (1+1) dimensional space-time. In such a process, we find the relation between the coupling constant $g(2D)$ in QCD2 and the coupling constant $g(4D)$ in QCD4. We also show that quarks and gluons in QCD2 acquire masses as a result of the compactification.

Koshelkin, Andrey V. [Moscow Institute for Physics and Engineering, Russia; Wong, Cheuk-Yin [ORNL

2012-01-01

46

IGUANA: a high-performance 2D and 3D visualisation system  

NASA Astrophysics Data System (ADS)

The IGUANA project has developed visualisation tools for multiple high-energy experiments. At the core of IGUANA is a generic, high-performance visualisation system based on OpenInventor and OpenGL. This paper describes the back-end and a feature-rich 3D visualisation system built on it, as well as a new 2D visualisation system that can automatically generate 2D views from 3D data, for example to produce R/Z or X/Y detector displays from existing 3D display with little effort. IGUANA has collaborated with the open-source gl2ps project to create a high-quality vector postscript output that can produce true vector graphics output from any OpenGL 2D or 3D display, complete with surface shading and culling of invisible surfaces. We describe how it works. We also describe how one can measure the memory and performance costs of various OpenInventor constructs and how to test scene graphs. We present good patterns to follow and bad patterns to avoid. We have added more advanced tools such as per-object clipping, slicing, lighting or animation, as well as multiple linked views with OpenInventor, and describe them in this paper. We give details on how to edit object appearance efficiently and easily, and even dynamically as a function of object properties, with instant visual feedback to the user.

Alverson, G.; Eulisse, G.; Muzaffar, S.; Osborne, I.; Taylor, L.; Tuura, L. A.

2004-11-01

47

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

48

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

49

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.

Bauer, Christina; Kobiela, Georg; Giessen, Harald

2012-01-01

50

Geometry Information  

NSDL National Science Digital Library

This article from New Zealand maths contains justifications for teaching geometry in the elementary grades and thoughts on how children learn geometry, including ideas from Piaget and the van Hieles. The article concludes with an example of how adults in a non-school setting would apply the van Hiele stages in an unfamiliar space.

2010-01-01

51

Infrared spectra of acetylene-water complexes: C2D2-H2O, C2D2-HDO, and C2D2-D2O  

NASA Astrophysics Data System (ADS)

Infrared spectra of C2D2-water complexes are studied in the 4.1 ?m region of the C2D2 ?3 fundamental band using a tunable diode laser source to probe a pulsed supersonic slit jet. Relatively large vibrational red shifts (-27.7 to -28.0 cm-1) are observed which are more easily interpretable than for the analogous C2H2 vibration thanks to the absence of Fermi resonance effects for C2D2. Noticeable homogeneous line broadening leads to estimates of upper state predissociation lifetimes of about 0.5, 0.9 and 1.1 ns for C2D2-H2O, -HDO, and -D2O, respectively. Transitions involving Ka = 0 and 1 levels are observed for C2D2-HDO, but there is a puzzling absence of Ka = 1 for C2D2-H2O and C2D2-D2O.

Rezaei, Mojtaba; Moazzen-Ahmadi, N.; McKellar, A. R. W.

2012-02-01

52

2-D axisymmetric line transport  

SciTech Connect

The methods used in the ALTAIR code for computing the transfer of spectral line radiation in two-dimensional axially-symmetric geometry are described. ALTAIR uses a variable-Eddington-tensor approach, in which the transfer equation of non-coherent line scattering is written in moment form, and the moments are closed with an assumed tensor relating the monochromatic pressure tensor and energy density; this Eddington tensor is obtained self-consistently using an accurate angle-dependent solution of the transfer equation. The finite element method for solving the moment system, and the discontinuous finite element method for solving the S{sub n} equation of transfer are described. Two applications of the method are discussed: line formation in uniform cylinders with different length-diameter ratios, and monochromatic transfer on an irregular x-y mesh (the Mordant test problem). 13 refs., 2 figs.

Castor, J.I.; Dykema, P.G. (Lawrence Livermore National Lab., CA (USA)); Klein, R.I. (Lawrence Livermore National Lab., CA (USA) California Univ., Berkeley, CA (USA). Dept. of Astronomy)

1990-11-20

53

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.

54

Connecting Geometry  

NSDL National Science Digital Library

A fully credited high school distance learning geometry course offered via the Internet to students throughout the Hawaiian islands as part of a grant-funded pilot project through the Hawaii Department of Education. During this E-School (electronic school) course Cathi Sanders, a teacher at Punahou School in Honolulu, and her students communicate through a Web page and via e-mail. Chapters include: 1. Communicating in Geometry; 2. Symmetry and Transformations; 3. Theorems in Geometry; 4. Congruent Triangles; 5. Triangle Properties; 6. Right Triangles; 7. Parallel Lines and Planes; 8. Polygons; 9. Similar Triangles; 10. Circles; 11. Perimeter and Area; 12. Surface Areas and Volumes.

Sanders, Cathleen V.

2007-02-24

55

Geometry Adventure  

NSDL National Science Digital Library

You are going on a geometry adventure! Your first task is to become an Angle Investigator Then you\\'re off to the Shape Factory to help out. Finally, you will complete 10 rounds of the Triangle Sort ...

Craighill, Miss

2007-11-12

56

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

SciTech Connect

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

Turner, L.R.

1991-01-01

57

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

58

Iconic Indexing by 2-D Strings  

Microsoft Academic Search

In this paper, we describe a new way of representing a symbolic picture by a two-dimensional string. A picture query can also be specified as a 2-D string. The problem of pictorial information retrieval then becomes a problem of 2-D subsequence matching. We present algorithms for encoding a symbolic picture into its 2-D string representation, reconstructing a picture from its

Shi-Kuo Chang; Qing-Yun Shi; Cheng-Wen Yan

1987-01-01

59

Reactivity Effects of Differences Between JEFF-3.1 and ENDF/B-VI.8 in Analysis of Six MASURCA Cores of the R-Z Program  

SciTech Connect

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

MIchael A. Pope

2010-02-01

60

Quantitative 2D liquid-state NMR.  

PubMed

Two-dimensional (2D) liquid-state NMR has a very high potential to simultaneously determine the absolute concentration of small molecules in complex mixtures, thanks to its capacity to separate overlapping resonances. However, it suffers from two main drawbacks that probably explain its relatively late development. First, the 2D NMR signal is strongly molecule-dependent and site-dependent; second, the long duration of 2D NMR experiments prevents its general use for high-throughput quantitative applications and affects its quantitative performance. Fortunately, the last 10?years has witnessed an increasing number of contributions where quantitative approaches based on 2D NMR were developed and applied to solve real analytical issues. This review aims at presenting these recent efforts to reach a high trueness and precision in quantitative measurements by 2D NMR. After highlighting the interest of 2D NMR for quantitative analysis, the different strategies to determine the absolute concentrations from 2D NMR spectra are described and illustrated by recent applications. The last part of the manuscript concerns the recent development of fast quantitative 2D NMR approaches, aiming at reducing the experiment duration while preserving - or even increasing - the analytical performance. We hope that this comprehensive review will help readers to apprehend the current landscape of quantitative 2D NMR, as well as the perspectives that may arise from it. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24700689

Giraudeau, Patrick

2014-06-01

61

Computational Geometry  

NSDL National Science Digital Library

A short article designed to provide an introduction to computational geometry, intended for topics whose geometric aspects are fairly straightforward, but for which the main questions involve efficient, accurate computation. A number of geometric questions arise involving large sets of points (e.g. which of these points are closest together?) which are arguably combinatorics or statistics, but which have been included here.

Rusin, David J., 1957-

2007-12-14

62

(2D)2PCA+(2D)2LDA: a new feature extraction for face recognition  

NASA Astrophysics Data System (ADS)

In this paper, we combine the advantages of (2D)2PCA and (2D)2LDA, and propose a two-stage framework: "(2D)2PCA+(2D)2LDA". In the first stage, a two-directional 2D feature extraction technique, (2D)2PCA, is employed to condense the dimension of image matrix; in the second stage, the two-directional 2D linear discriminant analysis (2D)2LDA is performed in the (2D)2PCA subspace to find the optimal discriminant feature vectors. In addition, the proposed method can take full advantage of the descriptive information and discriminant information of the image. Experiments conducted on ORL and Yale face databases demonstrate the effectiveness and robustness of the proposed method.

Huang, Guohong

2011-04-01

63

Crooked-line 2D seismic reflection imaging in crystalline terrains: Part 1, data processing  

Microsoft Academic Search

For cost and access reasons, most of the seismic re- flection data collected in crystalline terrains have been acquired by 2D crooked-line profiling. When the sur- vey geometry is significantly irregular and the geologic structures have cross-profile dip, several standard 2D imaging procedures severely underperform. As a re- sult, reflection signal is poorly aligned across individ- ual common midpoint (CMP)

Mladen R. Nedimovic?; Gordon F. Westz

2003-01-01

64

Geometry Dependence of Stellarator Turbulence  

SciTech Connect

Using the nonlinear gyrokinetic code package GENE/GIST, we study the turbulent transport in a broad family of stellarator designs, to understand the geometry-dependence of the microturbulence. By using a set of flux tubes on a given flux surface, we construct a picture of the 2D structure of the microturbulence over that surface, and relate this to relevant geometric quantities, such as the curvature, local shear, and effective potential in the Schrodinger-like equation governing linear drift modes.

H.E. Mynick, P. Xanthopoulos and A.H. Boozer

2009-08-10

65

Capturing nonlocal effects in 2D granular flows  

NASA Astrophysics Data System (ADS)

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

Kamrin, Ken; Koval, Georg

2013-03-01

66

2-D Hydrogen Molecule Using AMO Approximation.  

National Technical Information Service (NTIS)

The eigenenergies of the hydrogen molecule are calculated in the Alternate Molecular Orbital (AMO) approximation. Emphasis is given to two-dimensional (2-D) systems. Results are compared for the 2-D and 3-D cases and also with the singlet state of the Var...

E. A. Deandradaesilva I. C. Dacunhalima A. Ferreiradasilva

1985-01-01

67

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

68

Image Representation Using 2D Gabor Wavelets  

Microsoft Academic Search

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

Tai Sing Lee

1996-01-01

69

2D conglomerate crystallization of heptahelicene.  

PubMed

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

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

2014-08-14

70

Drop Size Distributions Measured by a 2D Video Disdrometer: Comparison with Dual-Polarization Radar Data.  

NASA Astrophysics Data System (ADS)

An analysis of drop size distributions (DSDs) measured in four very different precipitation regimes is presented and is compared with polarimetric radar measurements. The DSDs are measured by a 2D video disdrometer, which is designed to measure drop size, shape, and fall speed with unprecedented accuracy. The observations indicate that significant DSD variability exists not only from one event to the next, but also within each system. Also, despite having vastly different storm structures and maximum rain rates, large raindrops with diameters greater than 5 mm occurred with each system. By comparing the occurrence of large drops with rainfall intensity, the authors find that the largest median diameters are not always associated with the heaviest rainfall, but are sometimes located either in advance of convective cores or, occasionally, in stratiform regions where rainfall rates are relatively low. Disdrometer and polarimetric radar measurements of radar reflectivity Z, differential reflectivity ZDR, specific differential phase KDP, and R(Z) and R(KDP) rain-rate estimators are compared in detail. Overall agreement is good, but it is found that both R(Z) and R(KDP) underestimate rain rate when the DSD is dominated by small drops and overestimate rain rate when the DSD is dominated by large drops. The results indicate that a classification of different rain types (associated with different DSDs) should be an essential part of polarimetric rainfall estimation. Furthermore, observations suggest that ZDR is a key parameter for making such a distinction. Last, the authors compute and compare maximum and average of gamma shape, slope, and intercept parameters for all four precipitation events. Potential measurement errors with the 2D video disdrometer are also discussed.

Schuur, Terry J.; Ryzhkov, Alexander V.; Zrni, Dusan S.; Schönhuber, Michael

2001-06-01

71

SAR Target Feature Extraction and Recognition Based on 2D-DLPP  

NASA Astrophysics Data System (ADS)

In this paper, a new feature extraction algorithm named 2D-DLPP (Two-dimensional Discriminant Locality Preserving Projections) is used for SAR ATR (Synthetic Aperture Radar Automatic Target Recognition). First, SAR target images are preprocessed by log-transformation and 2D FFT, then 2D-DLPP is applied to extract target feature which can not only preserve local information by capturing the local geometry of manifold but also implement sample dimension reduction effectively. Finally, classification with SVM (Support Vector Machine) is performed to get the good recognition rate. Experimental results based on MSTAR (Moving and Stationary Target Acquisition and Recognition) SAR data demonstrate that 2D-DLPP can obtain more effective target feature and improve the recognition rate obviously compared with 2D-LDA (Two-dimensional Linear Discriminant Analysis).

Han, Ping; Wu, Jingxian; Wu, Renbiao

72

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

73

Thermal-stress analysis by coupling NIKE2D and TACO2D. [Tank rubber tracks  

Microsoft Academic Search

Several tank track designs were evaluated for the heating of the rubber pads. NIKE2D was used to analyze the rubber pads under mechanical loading and TACO2D to calculate thermal distributions within the pads. (DLC)

1984-01-01

74

Light field morphing using 2D features.  

PubMed

We present a 2D feature-based technique for morphing 3D objects represented by light fields. Existing light field morphing methods require the user to specify corresponding 3D feature elements to guide morph computation. Since slight errors in 3D specification can lead to significant morphing artifacts, we propose a scheme based on 2D feature elements that is less sensitive to imprecise marking of features. First, 2D features are specified by the user in a number of key views in the source and target light fields. Then the two light fields are warped view by view as guided by the corresponding 2D features. Finally, the two warped light fields are blended together to yield the desired light field morph. Two key issues in light field morphing are feature specification and warping of light field rays. For feature specification, we introduce a user interface for delineating 2D features in key views of a light field, which are automatically interpolated to other views. For ray warping, we describe a 2D technique that accounts for visibility changes and present a comparison to the ideal morphing of light fields. Light field morphing based on 2D features makes it simple to incorporate previous image morphing techniques such as nonuniform blending, as well as to morph between an image and a light field. PMID:15631126

Wang, Lifeng; Lin, Stephen; Lee, Seungyong; Guo, Baining; Shum, Heung-Yeung

2005-01-01

75

The 2dF Galaxy Redshift Survey (2dFGRS) (2dFGRS Team, 1998-2003)  

NASA Astrophysics Data System (ADS)

The 2dF Galaxy Redshift Survey (2dFGRS) is a major spectroscopic survey taking full advantage of the unique capabilities of the 2dF facility built by the Anglo-Australian Observatory. The 2dFGRS is integrated with the 2dF QSO survey (2QZ, Cat. VII/241). The 2dFGRS obtained spectra for 245591 objects, mainly galaxies, brighter than a nominal extinction-corrected magnitude limit of bJ=19.45. Reliable (quality>=3) redshifts were obtained for 221414 galaxies. The galaxies cover an area of approximately 1500 square degrees selected from the extended APM Galaxy Survey in three regions: a North Galactic Pole (NGP) strip, a South Galactic Pole (SGP) strip, and random fields scattered around the SGP strip. Redshifts are measured from spectra covering 3600-8000 Angstroms at a two-pixel resolution of 9.0 Angstrom and a median S/N of 13 per pixel. All redshift identifications are visually checked and assigned a quality parameter Q in the range 1-5; Q>=3 redshifts are 98.4% reliable and have an rms uncertainty of 85 km/s. The overall redshift completeness for Q>=3 redshifts is 91.8% but this varies with magnitude from 99% for the brightest galaxies to 90% for objects at the survey limit. The 2dFGRS data base is available on the World Wide Web at http://www.mso.anu.edu.au/2dFGRS/. (6 data files).

Colless, M.; Dalton, G.; Maddox, S.; Sutherland, W.; Norberg, P.; Cole, S.; Bland-Hawthorn, J.; Bridges, T.; Cannon, R.; Collins, C.; Couch, W.; Cross, N.; Deeley, K.; de Propris, R.; Driver, S. P.; Efstathiou, G.; Ellis, R. S.; Frenk, C. S.; Glazebrook, K.; Jackson, C.; Lahav, O.; Lewis, I.; Lumsden, S.; Madgwick, D.; Peacock, J. A.; Peterson, B. A.; Price, I.; Seaborne, M.; Taylor, K.

2007-11-01

76

Anomalous Dynamics in 2D Polymer Melts  

NASA Astrophysics Data System (ADS)

The dynamics in polymer monolayers where chains are strongly confined and adopt 2D conformations are drastically different to those in the bulk. It is shown that viscoelastic hydrodynamic interactions play a major role defining the anomalous chain diffusion properties in such systems where chains cannot cross each other. We developed a quantitative analytical theory of polymer subdiffusion in 2D systems revealing a complex behavior controlled by a delicate interplay of inertial, viscoelastic hydrodynamic interactions, finite-box-size and frictional effects. The theory is fully supported by extensive momentum-conserving and Langevin molecular-dynamics simulation data explaining the highly cooperative character of 2D polymer motions.

Meyer, H.; Semenov, A. N.

2012-12-01

77

Quantitative 2D liquid-state NMR.  

PubMed

Two-dimensional liquid-state NMR has a very high potential to simultaneously determine the absolute concentration of small molecules in complex mixtures, thanks to its capacity to separate overlapping resonances. However, 2D NMR experiments suffer from a number of limitations which affect their quantitative performance. The last ten years have witnessed an increasing number of contributions where quantitative approaches based on 2D NMR were developed and applied to solve real analytical issues. In this review special feature article, Dr. Patrick Giraudeau (University of Nantes) describes these recent efforts to reach a high trueness and precision in quantitative measurements by 2D NMR. Different strategies are presented in a critical way, combining NMR developments with analytical chemistry protocols. The recent efforts to speed up the duration of quantitative 2D NMR experiments are particularly highlighted. PMID:24817633

Giraudeau, P

2014-06-01

78

Hydro schemes and reactive flow in 1-d and 2-d  

Microsoft Academic Search

The behavior of the implementation of Craig Tarver's reactive flow model for high explosives in a hydro code is investigated. The model produces the correct shock propagation rates. The effects of geometry, zoning and artificial viscosity are compared in one (1D) and two (2D) dimensions. Sensitivities to the solution scheme of the hydro equations are also investigated. A comparison with

D L Morgan; K Sinz

1998-01-01

79

Parallel algorithms for 2-D cylindrical transport equations of Eigenvalue problem  

SciTech Connect

In this paper, aimed at the neutron transport equations of eigenvalue problem under 2-D cylindrical geometry on unstructured grid, the discrete scheme of Sn discrete ordinate and discontinuous finite is built, and the parallel computation for the scheme is realized on MPI systems. Numerical experiments indicate that the designed parallel algorithm can reach perfect speedup, it has good practicality and scalability. (authors)

Wei, J.; Yang, S. [Institute of Applied Physics and Computational Mathematics, No. 2, Fenhao Donglu, Haidian District, Beijng (China)] [Institute of Applied Physics and Computational Mathematics, No. 2, Fenhao Donglu, Haidian District, Beijng (China)

2013-07-01

80

Characterization of fluidic microassembly for immobilization and positioning of Drosophila embryos in 2-D arrays  

Microsoft Academic Search

A technique for the positioning and immobilization of Drosophila embryos in 2-D arrays for use in high throughput microinjection experiments has been characterized. The method is based on fluidic microassembly, and immobilization yield, the number of misplaced embryos, alignment properties, and adhesion force of the embryos have been measured for samples with four different pad geometries. For samples with 250?m×400?m

Ralph W. Bernstein; Xiaojing Zhang; Stefan Zappe; Matt Fish; Matthew Scott; Olav Solgaard

2004-01-01

81

2D numerical modelling of the gas temperature in a high-temperature high-power strontium atom laser excited by nanosecond pulsed longitudinal discharge in a He-SrBr2 mixture  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

82

STP Random Walk 2D Program  

NSDL National Science Digital Library

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

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

2008-10-10

83

The 2D lingual appliance system.  

PubMed

The two-dimensional (2D) lingual bracket system represents a valuable treatment option for adult patients seeking a completely invisible orthodontic appliance. The ease of direct or simplified indirect bonding of 2D lingual brackets in combination with low friction mechanics makes it possible to achieve a good functional and aesthetic occlusion, even in the presence of a severe malocclusion. The use of a self-ligating bracket significantly reduces chair-side time for the orthodontist, and the low-profile bracket design greatly improves patient comfort. PMID:24005953

Cacciafesta, Vittorio

2013-09-01

84

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

85

tt * geometry in 3 and 4 dimensions  

NASA Astrophysics Data System (ADS)

We consider the vacuum geometry of supersymmetric theories with 4 supercharges, on a flat toroidal geometry. The 2 dimensional vacuum geometry is known to be captured by the tt * geometry. In the case of 3 dimensions, the parameter space is ( T 2 × ) N and the vacuum geometry turns out to be a solution to a generalization of monopole equations in 3 N dimensions where the relevant topological ring is that of line operators. We compute the generalization of the 2d cigar amplitudes, which lead to S 2 × S 1 or S 3 partition functions which are distinct from the supersymmetric partition functions on these spaces, but reduce to them in a certain limit. We show the sense in which these amplitudes generalize the structure of 3d Chern-Simons theories and 2d RCFT's. In the case of 4 dimensions the parameter space is of the form X M,N = ( T 3 × ) M × T 3 N , and the vacuum geometry is a solution to a mixture of generalized monopole equations and generalized instanton equations (known as hyper-holomorphic connections). In this case the topological rings are associated to surface operators. We discuss the physical meaning of the generalized Nahm transforms which act on all of these geometries.

Cecotti, Sergio; Gaiotto, Davide; Vafa, Cumrun

2014-05-01

86

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

87

Granular Flow in a 2D Couette-Taylor Experiment  

NASA Astrophysics Data System (ADS)

The dynamics of granular materials pose interesting problems both in gravity and low-gravity environments due to their high dissipation in collisions and their propensity to jam. In addition, it has been shown that even moderate flows can achieve supersonic conditions within a granular medium. A few thousand permeable spheres are motivated to flow in a 2D geometry via a magnetic field and then sheared mechanically at a boundary wall. The novel Couette-Taylor design of the apparatus with one soft boundary allows for shear flow in the 2D system to be studied in the absence of jamming. High-speed digital imaging and particle tracking software allow the system to be studied for a variety of flow speeds and shear rates at the boundary wall. The apparatus can also be used to study flow past an obstacle in analogy to a wind tunnel for granular flows. E. Rericha, C. Bizon, M. D. Shattuck, and H. Swinney, Phys. Rev. Lett., 88, 014302 (2002).

Olafsen, Jeffrey

2006-11-01

88

Ion source modeling with LORENTZ2D  

Microsoft Academic Search

LORENTZ-2D is a boundary element package developed and marketed by Integrated Engineering Software, which can be used for a variety of charged particle optical analyses. In this article, the program is used in the analysis of two types of Cs+ sputter ion sources. The results are presented and compared versus some earlier empirical and numerical simulations.

Ali Asi

2002-01-01

89

Sketching with projective 2D strokes  

Microsoft Academic Search

Freehand sketching has long had appeal as an artistic medium for conceptual design because of its immediacy in capturing and communicating design intent and visual experience. We present a sketching paradigm that supports the early stages of design by preserving the fluidity of traditional freehand drawings. In addition, it attempts to fill the gap between 2D drawing programs, which have

Osama Tolba; Julie Dorsey; Leonard McMillan

1999-01-01

90

Hopkinson bar simulation using DYNA2D  

SciTech Connect

A finite-element simulation of a Split Hopkinson's bar (Kolsky apparatus) technique involving mortar specimens is accomplished with DYNA2D, an explicit two-dimensional finite-element code. Calculations are compared with experimental results contained in a University of Florida report Dynamic Response of Concrete and Concrete Structures, and with analytic solutions of the appropriate wave propagation problem.

Smith, J.A.; Glover, T.A.

1985-01-08

91

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

SciTech Connect

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

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

1996-07-01

92

Crossing the c=1 barrier in 2D Lorentzian quantum gravity  

NASA Astrophysics Data System (ADS)

In an extension of earlier work we investigate the behavior of two-dimensional (2D) Lorentzian quantum gravity under coupling to a conformal field theory with c>1. This is done by analyzing numerically a system of eight Ising models (corresponding to c=4) coupled to dynamically triangulated Lorentzian geometries. It is known that a single Ising model couples weakly to Lorentzian quantum gravity, in the sense that the Hausdorff dimension of the ensemble of two-geometries is two (as in pure Lorentzian quantum gravity) and the matter behavior is governed by the Onsager exponents. By increasing the amount of matter to eight Ising models, we find that the geometry of the combined system has undergone a phase transition. The new phase is characterized by an anomalous scaling of spatial length relative to proper time at large distances, and as a consequence the Hausdorff dimension is now three. In spite of this qualitative change in the geometric sector, and a very strong interaction between matter and geometry, the critical exponents of the Ising model retain their Onsager values. This provides evidence for the conjecture that the KPZ values of the critical exponents in 2D Euclidean quantum gravity are entirely due to the presence of baby universes. Lastly, we summarize the lessons learned so far from 2D Lorentzian quantum gravity.

Ambjørn, J.; Anagnostopoulos, K.; Loll, R.

2000-02-01

93

Perturbation theory of 2D decagonal quasicrystals  

NASA Astrophysics Data System (ADS)

A perturbation method for solving elastic 3D problems for 2D decagonal quasicrystals with point groups 10 mm, 1022. overline10m2 and 10/mmm is proposed. We obtain a uniformly valid asymptotic solution of the elastic field by regarding phason field as a perturbation to phonon field and introducing a perturbation parameter ?= R/ cll, where cll and R are elastic constants of phonon field and phonon-phason coupling, respectively. A general solution for the equations of order zero is given in terms of five “harmonic” functions. As a simple application of the above theory, considering an infinite 2D decagonal quasicrystal of point group 10 mm weakened by a circular crack, we obtain the uniformly valid asymptotic solutions up to O( ?2) for the mode I loading.

Peng, Yan-ze; Fan, Tian-you

2002-02-01

94

Foot measurements from 2D digital images  

Microsoft Academic Search

Foot measurements play an important role in the design of comfortable footwear products. This study proposed a non-invasive and efficient means to obtain foot measurements from 2D digital foot images. The hardware of the proposed image-based measuring system was easy to set up and the developed measuring system was tested for 9 foot measurements with ten male subjects who were

Shuping Xiong; Yulin Li; Yi Zhu; Jingxing Qian; Dong Yang

2010-01-01

95

2-D kettle reboiler circulation model  

Microsoft Academic Search

A 2-D model is developed for sections of a kettle reboiler where liquid\\/vapour disengagement is not severe. Using a trial set of boundary conditions it is shown that the influence of flow around the periphery of the bundle has negligible effect on flow distribution over the tubes. Uniform heat flux solutions are obtained for q=20 and 50 kW\\/m2 boiling pentane

B. M. Burnside

1999-01-01

96

MAGNUM-2D computer code: user's guide  

SciTech Connect

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

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

1985-01-01

97

2D and 3D meso-scale finite element models for ravelling analysis of porous asphalt concrete  

Microsoft Academic Search

This paper presents 2D and 3D meso-level mechanical modelling for numerical analysis of ravelling resistance of porous asphalt concrete (PAC). The complex geometry of PAC was simplified so that the main components (aggregate particle, mortar, interfacial zone and air void) in the actual mixture were represented in the meso-scale model separately. Three different models, comprising 2D representations of different particle

L. T. Mo; M. Huurman; S. P. Wu; A. A. A. Molenaar

2008-01-01

98

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

Microsoft Academic Search

We present direct numerical simulation of two-dimensional decaying turbulence in wall bounded domains. The Navier-Stokes equations\\u000a are solved in a periodic square domain using the vorticity-velocity formulation. The bounded domain is imbedded in the periodic\\u000a domain and the no-slip boundary conditions on the wall are imposed using a volume penalisation technique. The numerical integration\\u000a is done with a Fourier pseudo-spectral

Kai Schneider; Marie Farge

99

Partial realization of 2-D discrete linear system and 2-D Pade approximation and reduction of 2-D rational transfer function  

Microsoft Academic Search

A method is presented for determining the unknown degree and system function of any 2-D discrete linear shift-invariant system characterized by a 2-D impulse response array, i.e., the coefficients of the formal double power series that are obtained by expanding a rational transfer function. Problems of 2-D Pade approximation and 2-D system reduction can be solved by the same method

S. Sakata

1990-01-01

100

ENERGY LANDSCAPE OF 2D FLUID FORMS  

SciTech Connect

The equilibrium states of 2D non-coarsening fluid foams, which consist of bubbles with fixed areas, correspond to local minima of the total perimeter. (1) The authors find an approximate value of the global minimum, and determine directly from an image how far a foam is from its ground state. (2) For (small) area disorder, small bubbles tend to sort inwards and large bubbles outwards. (3) Topological charges of the same sign repel while charges of opposite sign attract. (4) They discuss boundary conditions and the uniqueness of the pattern for fixed topology.

Y. JIANG; ET AL

2000-04-01

101

Point Charge Forces in 2D Model  

NSDL National Science Digital Library

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

Duffy, Andrew

2010-04-16

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

Pseudogaps in the 2D Hubbard Model.  

PubMed

We study the pseudogaps in the spectra of the 2D Hubbard model using both finite-size and dynamical cluster approximation (DCA) quantum Monte Carlo calculations. At half-filling, a charge pseudogap, accompanied by non-Fermi-liquid behavior in the self-energy, is shown to persist in the thermodynamic limit. The DCA (finite-size) method systematically underestimates (overestimates) the width of the pseudogap. A spin pseudogap is not seen at half-filling. At finite doping, a divergent d-wave pair susceptibility is observed. PMID:11136113

Huscroft; Jarrell; Maier; Moukouri; Tahvildarzadeh

2001-01-01

104

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

105

A salt-bridge structure in solution revealed by 2D-IR spectroscopy.  

PubMed

Salt bridges are important interactions for the stability of protein conformations, but up to now it has been difficult to determine salt-bridge geometries in solution. Here we characterize the spatial structure of a salt bridge between guanidinium (Gdm(+)) and acetate (Ac(-)) using two-dimensional vibrational (2D-IR) spectroscopy. We find that as a result of salt bridge formation there is a significant change in the infrared response of Gdm(+) and Ac(-), and cross peaks between them appear in the 2D-IR spectrum. From the 2D-IR spectrum we determine the relative orientation of the transition-dipole moments of the vibrational modes of Gdm(+) and Ac(-), as well as the coupling between them. PMID:24676430

Huerta-Viga, Adriana; Domingos, Sérgio R; Amirjalayer, Saeed; Woutersen, Sander

2014-07-01

106

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

107

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.

108

Influence of E × B and ? B drift terms in 2-D edge\\/SOL transport simulations  

Microsoft Academic Search

Classical particle drifts across the magnetic field can play an important role in tokamak edge-plasma transport. The relative influence of these terms is studied for self-consistent simulations by including them, together with anomalous diffusion transport, in a 2-D fluid model of edge-plasma transport for the DIII-D tokamak geometry. The drifts cause asymmetries in the plasma parameters between the inner and

T. D. Rognlien; G. D. Porter; D. D. Ryutov

1999-01-01

109

On the long time behavior of decaying 2D turbulence in bounded domains  

Microsoft Academic Search

Two--dimensional turbulence in bounded domains has many applications in geophysical flows, e.g., the prediction of coastal currents to study the transport and mixing of pollutants in oceans. We present Direct Numerical Simulations of 2D turbulence in bounded domains for different geometries. The Navier-Stokes equations are solved in a periodic square domain using the vorticity--velocity formulation. The bounded domain is imbedded

Kai Schneider; Marie Farge

2006-01-01

110

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

111

Extended Aperture 2-D Direction Finding With a Two-Parallel-Shape-Array Using Propagator Method  

Microsoft Academic Search

In this letter, we propose a two-parallel-shape array geometry, consisting of sensors spaced much farther apart than a half-wavelength, to improve estimation accuracy via aperture extension for two-dimensional (2D) direction finding. First, the subarray parallel with the x-axis is employed to extract automatically paired high-variance but unambiguous y-axis direction cosines and low-variance but cyclically ambiguous x-axis direction cosines. Then, the

Jin He; Zhong Liu

2009-01-01

112

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

113

H? reduced-order approximation of 2-D digital filters  

Microsoft Academic Search

This paper considers the H? reduced-order approximation of two-dimensional (2-D) digital filters using the linear matrix inequality (LMI) approach, The 2-D digital filter is described by the 2-D Roesser model. We shall first establish LMI conditions for which a 2-D system is bounded real. This bounded realness property then allows us to derive solvability conditions for the 2-D H? reduced-order

hunling Du; Lihua Xie; Yeng Chai Soh

2001-01-01

114

Cytochrome P450 2D6 as a Model Antigen  

PubMed Central

Cytochrome P450 2D6 (CYP2D6) has been identified as the major autoantigen in type 2 autoimmune hepatitis (AIH). However, because of a lack of appropriate animal models, the etiology of AIH is still poorly understood. We generated a mouse model for AIH using the human CYP2D6 as a triggering molecule for autoimmunity. We infected wild-type FVB mice with an adenovirus expressing human CYP2D6 (Ad-2D6) to break self-tolerance to the mouse CYP2D6 homologues. Ad-2D6-infected mice showed persistent features of liver damage including hepatic fibrosis, cellular infiltrations, focal-to-confluent necrosis and generation of anti-CYP2D6 antibodies, which predominantly recognized the identical immunodominant epitope recognized by LKM-1 antibodies from AIH patients. Interestingly, Ad-2D6 infection of transgenic mice expressing the human CYP2D6 (CYP2D6 mice) resulted in delayed kinetics and reduced severity of liver damage. However, the quantity and quality of anti-CYP2D6 antibodies was only moderately reduced in CYP2D6 mice. In contrast, the frequency of CYP2D6-specific CD4 and CD8 T cells was dramatically decreased in CYP2D6 mice, indicating the presence of a strong T cell tolerance to human CYP2D6 established in CYP2D6 mice, but not in wild-type mice. CYP2D6-specific T cells reacted to human CYP2D6 peptides with intermediate homology to the mouse homologues, but not to those with high homology, indicating that molecular mimicry rather than molecular identity breaks tolerance and subsequently causes severe persistent autoimmune liver damage. The CYP2D6 model provides a platform to investigate mechanisms involved in the immunopathogenesis of autoimmune-mediated chronic hepatic injury and evaluate possible ways of therapeutic interference.

Christen, Urs; Holdener, Martin; Hintermann, Edith

2010-01-01

115

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

116

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

117

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

118

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

119

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

120

The mouse ruby-eye 2(d) (ru2(d) /Hps5(ru2-d) ) allele inhibits eumelanin but not pheomelanin synthesis.  

PubMed

The novel mutation named ru2(d) /Hps5(ru2-d) , characterized by light-colored coats and ruby-eyes, prohibits differentiation of melanocytes by inhibiting tyrosinase (Tyr) activity, expression of Tyr, Tyr-related protein 1 (Tyrp1), Tyrp2, and Kit. However, it is not known whether the ru2(d) allele affects pheomelanin synthesis in recessive yellow (e/Mc1r(e) ) or in pheomelanic stage in agouti (A) mice. In this study, effects of the ru2(d) allele on pheomelanin synthesis were investigated by chemical analysis of melanin present in dorsal hairs of 5-week-old mice from F2 generation between C57BL/10JHir (B10)-co-isogenic ruby-eye 2(d) and B10-congenic recessive yellow or agouti. Eumelanin content was decreased in ruby-eye 2(d) and ruby-eye 2(d) agouti mice, whereas pheomelanin content in ruby-eye 2(d) recessive yellow and ruby-eye 2(d) agouti mice did not differ from the corresponding Ru2(d) /- mice, suggesting that the ru2(d) allele inhibits eumelanin but not pheomelanin synthesis. PMID:23672590

Hirobe, Tomohisa; Ito, Shosuke; Wakamatsu, Kazumasa

2013-09-01

121

Predicting Fracture Using 2D Finite Element Modeling  

PubMed Central

A decrease in bone density at the hip or spine has been shown to increase the risk of fracture. A limitation of the bone mineral density (BMD) measurement is that it provides only a measure of a bone samples average density when projected onto a 2D surface. Effectively, what determines bone fracture is whether an applied load exceeds ultimate strength, with both bone tissue material properties (can be approximated through bone density), and geometry playing a role. The goal of this project was to use bone geometry and BMD obtained from radiographs and DXA measurements respectively to estimate fracture risk, using a two-dimensional finite element model (FEM) of the sagittal plane of lumbar vertebrae. The Canadian Multicenter Osteoporosis Study (CaMos) data was used for this study. There were 4194 men and women over the age of 50 years, with 786 having fractures. Each subject had BMD testing and radiographs of their lumbar vertebrae. A single two dimensional FEM of the first to fourth lumbar vertebra was automatically generated for each subject. Bone tissue stiffness was assigned based on the BMD of the individual vertebrae, and adjusted for patient age. Axial compression boundary conditions were applied with a force proportional to body mass. The resulting overall strain from the applied force was found. Men and women were analyzed separately. At baseline, the sensitivity of BMD to predict fragility fractures in women and men was 3.77 % and 0.86 %, while the sensitivity of FEM to predict fragility fractures for women and men was 10.8 % and 11.3 %. The FEM ROC curve demonstrated better performance compared to BMD. The relative risk of being considered at high fracture risk using FEM at baseline, was a better predictor of 5 year incident fragility fracture risk compared to BMD.

MacNeil, J.A.M.; Adachi, J.D; Goltzman, D; Josse, R.G; Kovacs, C.S; Prior, J.C; Olszynski, W; Davison, K.S.; Kaiser, S.M

2013-01-01

122

Predicting fracture using 2D finite element modelling.  

PubMed

A decrease in bone density at the hip or spine has been shown to increase the risk of fracture. A limitation of the bone mineral density (BMD) measurement is that it provides only a measure of a bone sample's average density when projected onto a 2D surface. Effectively, what determines bone fracture is whether an applied load exceeds ultimate strength, with both bone tissue material properties (can be approximated through bone density), and geometry playing a role. The goal of this project was to use bone geometry and BMD obtained from radiographs and DXA measurements respectively to estimate fracture risk, using a two-dimensional finite element model (FEM) of the sagittal plane of lumbar vertebrae. The Canadian Multicentre Osteoporosis Study (CaMos) data was used for this study. There were 4194 men and women over the age of 50 years, with 786 having fractures. Each subject had BMD testing and radiographs of their lumbar vertebrae. A single two dimensional FEM of the first to fourth lumbar vertebra was automatically generated for each subject. Bone tissue stiffness was assigned based on the BMD of the individual vertebrae, and adjusted for patient age. Axial compression boundary conditions were applied with a force proportional to body mass. The resulting overall strain from the applied force was found. Men and women were analyzed separately. At baseline, the sensitivity of BMD to predict fragility fractures in women and men was 3.77% and 0.86%, while the sensitivity of FEM to predict fragility fractures for women and men was 10.8% and 11.3%. The FEM ROC curve demonstrated better performance compared to BMD. The relative risk of being considered at high fracture risk using FEM at baseline, was a better predictor of 5 year incident fragility fracture risk compared to BMD. PMID:21959170

MacNeil, J A M; Adachi, J D; Goltzman, D; Josse, R G; Kovacs, C S; Prior, J C; Olszynski, W; Davison, K S; Kaiser, S M

2012-05-01

123

Vortices in the 2D Kuramoto model  

NASA Astrophysics Data System (ADS)

We study the synchronization of oscillators in 2D lattices with nearest neighbor coupling. The boundaries between synchronized domains are due to the motion of vortices. Since the phase winds by 2pi around a vortex, it generates 2pi phase slips between oscillators across its path. Thus, the synchronization behavior of the system can be viewed in terms of the production, movement, and annihilation of vortex pairs. Although the Kuramoto model is nonlinear, we show how to use the steady state solution of the linearized model to predict where the vortices are produced and how they move. We also study vortex density as a function of system size and coupling. This vortex approach may lead to an analytical understanding of why the lower critical dimension for macroscopic entrainment is 2.

Lee, Tony; Tam, Heywood; Refael, Gil; Rogers, Jeffrey; Cross, Michael

2010-03-01

124

Falling Body On Rotating Earth 2D  

NSDL National Science Digital Library

The EJS Falling Body On Rotating Earth 2D model illustrates the trajectory of an object dropped from rest (relative to the rotating Earth) from a point above Earth's equator. The user can set the initial height of the object above (or below) the Earth's surface, as well as the rotational speed of Earth. The motion of the object can be viewed from an inertial reference frame, or from a frame that rotates with the Earth (illustrating the effects of the so-called "Coriolis force"). The simulation can be made to stop when the object hits Earth's surface, or it can allow the object to move through the Earth. The user can select from a variety of options that control the gravitational and resistive forces acting on the object as it falls. The simulation can also generate a plot of the object's longitude (initially assumed to be zero) as a function of time.

Timberlake, Todd

2012-07-26

125

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

126

Stellar Aberration 2D JS Model  

NSDL National Science Digital Library

The Stellar Aberration 2D JS Model illustrates the phenomenon known as the aberration of starlight, first reported by James Bradley in 1729. Aberration occurs because light has a finite speed, and thus light from a star takes a finite amount of time to travel through the tube of a telescope. During this time, the telescope moves as a result of Earth's rotational and orbital motions (in this case, the orbital motion is more important because it is faster). Therefore, if the telescope is pointed directly at the star the starlight will hit the sides of the tube before reaching the eyepiece. To see the star the telescope must be pointed forward (i.e. in the direction of Earth's motion) very slightly. The simulation shows a telescope (depicted as a red rectangle) and a star (white point) directly overhead. When the simulation is run a pulse of light is emitted from the star and travels straight downward to Earth. The telescope moves to the right due to Earth's motion. As a result, if the telescope is pointed straight up (ie toward the actual location of the star) the pulse of light will not reach the bottom of the telescope. Controls allow the user to set the speed of Earth and the tilt of the telescope. The user can modify the tilt until the starlight reaches the bottom of the telescope. Alternately, the user can use the Options menu to set the telescope to the correct tilt for the current speed setting. The Stellar Aberration 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

2014-03-08

127

Simulation of 2D Magnetoconvection on Parallel Computers  

NASA Astrophysics Data System (ADS)

Magnetoconvection, or the interaction of magnetic fields with a thermally-driven plasma flow, is a phenomenon of great importance to stellar interiors---for example, it is thought to be the underlying cause of solar and stellar dynamos. Computer simulation is necessary for investigating problems of magnetoconvection because of its inherent nonlinearities. The advent of high-speed parallel computers opens up fresh possibilities for high-resolution simulation studies of the nonlinear dynamics of magnetoconvection. This presentation will outline the approach taken in parallelizing a 2D Boussinesq MHD model code designed to run on the Cornell Theory Center's IBM SP2 computer. Here, the plasma is imagined to be confined in a rotating, heated cylindrical annulus and threaded with azimuthal magnetic fields; this configuration is roughly analogous to a near-equatorial slice of the Sun. Such a geometry is germane to the study of many interesting types of nonlinear MHD waves, some of which may self-modulate or even reverse their direction of propagation (Lantz, Ph.D. thesis, 1992). Computational issues such as domain decomposition, parallel solution of a Poisson equation, and algorithmic optimization will be discussed.

Lantz, Steven R.

1996-05-01

128

Numerical models of 2-D and 3-D geophysical convection  

SciTech Connect

A suite of computational models has been developed which simulate thermal/chemical convection over a wide range of Rayleigh numbers both in 2-D annular and 3-D Cartesian geometries, for small Reynolds number flow, and a variety of boundary conditions. These simulators are revealing the patterns of convection that may occur in the earth, from mantle scale down to more localized regions such as mid-ocean spreading centers, on down to the scale of magma chambers. Features such as surface plates, variable viscosity and chemical buoyancy can have a dramatic impact on convective patterns compared to those seen in simple, constant property, free or fixed surface systems. In most cases, the nonlinear dynamics of these systems derive from thermal and chemical forces, rather than inertial. These models can be used to study general features and dynamics of convecting viscous fluids, and can also be used to constrain possible explanations for geophysical observations such as heat flow, gravity, topography, plate speeds, and isotopic distributions. Computational resources have reached a level at which numerical solutions of complex processes are feasible.

Travis, B.J.

1990-01-01

129

2D Fluidization of Nanomaterials by Biomimetic Membranes  

NASA Astrophysics Data System (ADS)

The last decade has seen much progress in the synthesis and manufacturing of a large variety of nanometer sized particles of different materials, geometries and properties. If they can be assembled into larger structures, these manmade nano-objects are posed to be the ``atoms'' and ``molecules'' of new materials. In order to facilitate their dynamic rearrangements we have developed a method that uses material specific binding peptides to anchor nano-objects to lipids in supported bilayers (SLB). In this study we use single walled carbon nanotubes (CNT) with a mean length of 1 micrometer as model of a potential nano-building block. By fluorescently labeling CNTs we are able to use video-microscopy to investigate the dynamic behavior of membrane anchored CNTs. We show that the 2D fluidity of the lipid membrane can be successfully templated on the CNTs and that they stay laterally mobile while being confined to a plane. Furthermore, the dependence of CNT mobility on specific binding stoichiometries is discussed.

Kelly, Kathleen; Forstner, Martin

2013-03-01

130

2D Fluidization of Nanomaterials by Biomimetic Membranes  

NASA Astrophysics Data System (ADS)

The last decade has seen much progress in the synthesis and manufacturing of a large variety of nanometer sized particles of different materials, geometries and properties. If they can be assembled into larger structures, these manmade nano-objects are posed to be the ``atoms'' and ``molecules'' of new materials. In order to facilitate their dynamic rearrangements we have developed a method that uses material specific binding peptides to anchor nano-objects to lipids in supported bilayers (SLB). In this study we use single walled carbon nanotubes (CNT) with a mean length of 1 micrometer as model of a potential nano-building block. By fluorescently labeling CNTs we are able to use video-microscopy to investigate the dynamic behavior of membrane anchored CNTs. We show that the 2D fluidity of the lipid membrane can be successfully templated on the CNTs and that they stay laterally mobile while being confined to a plane. Furthermore, the dependence of CNT mobility on specific binding stoichiometries is discussed.

Kelly, Kathleen; Forstner, Martin

2012-02-01

131

Anvaedande av 2D/3D. (Use of 2D3D).  

National Technical Information Service (NTIS)

It is today possible to use 3D presentations in airplanes and in MOUT situations, but the main question is if the new possibility helps soldiers in the field. In the choice between 2D and 3D, it is necessary to take into account the operators assignment a...

P. Lif

2004-01-01

132

Math Forum: Geometry  

NSDL National Science Digital Library

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

1997-01-01

133

On the Self-Affine Fractal Geometry of Plasma-Sprayed Surfaces  

NASA Astrophysics Data System (ADS)

Surface roughness strongly controls essential properties of thermally sprayed wear- and corrosion-resistant coatings including their mechanical adhesion to the substrate, tribological performance, efficient retention of lubricating materials, and also the presence of sufficient carrying surface able to support the wear couple along the line of contact expressed by the Abbott-Firestone curve. The determination of the surface fractal geometry may yield useful information on the topography of plasma-sprayed coatings beyond that provided by a single roughness parameter such as R a or R z. The fractal geometry of atmospheric plasma-sprayed chromium oxide coatings, deposited according to two different statistical experimental design protocols, was assessed through determination of the Hurst exponent H of fractal Brownian motion (fBM), as well as the area-scaled fractal complexity (ASFC) obtained by triangular tessellation ("patchwork" method). Attempts were made to correlate fractality with coating adhesion strength.

Heimann, Robert B.

2011-06-01

134

Morphological changes in 2D foams  

NASA Astrophysics Data System (ADS)

We consider equilibrium configurations of 2D soap foams with ideal gas inside the bubbles for various values of the parameters of the foam. For a given foam there is a critical value of the total area such that the morphology of the foam is drastically different for areas smaller and larger than this critical value. When the area of the foam is increased above the critical value, our theory predicts a first-order phase transition from a uniform to a non-uniform state. The non-uniform state consists of a few big bubbles and many small bubbles. Numerical simulations show that instead of undergoing an instantaneous transition, the foam suffers a sequence of structural transformations. This phenomenon is caused by the smallness of fluctuations compared with the energy required to overcome Plateau's rules. The statistics of the sequence of transformations depends on the imposed `reconnection temperature', just as the packing properties of a granular material depend on the shaking of the container.

Vainchtein, Dmitri L.; Aref, Hassan

1999-11-01

135

2D Radiative Processes Near Cloud Edges  

NASA Technical Reports Server (NTRS)

Because of the importance and complexity of dynamical, microphysical, and radiative processes taking place near cloud edges, the transition zone between clouds and cloud free air has been the subject of intense research both in the ASR program and in the wider community. One challenge in this research is that the one-dimensional (1D) radiative models widely used in both remote sensing and dynamical simulations become less accurate near cloud edges: The large horizontal gradients in particle concentrations imply that accurate radiative calculations need to consider multi-dimensional radiative interactions among areas that have widely different optical properties. This study examines the way the importance of multidimensional shortwave radiative interactions changes as we approach cloud edges. For this, the study relies on radiative simulations performed for a multiyear dataset of clouds observed over the NSA, SGP, and TWP sites. This dataset is based on Microbase cloud profiles as well as wind measurements and ARM cloud classification products. The study analyzes the way the difference between 1D and 2D simulation results increases near cloud edges. It considers both monochromatic radiances and broadband radiative heating, and it also examines the influence of factors such as cloud type and height, and solar elevation. The results provide insights into the workings of radiative processes and may help better interpret radiance measurements and better estimate the radiative impacts of this critical region.

Varnai, T.

2012-01-01

136

2D/3D facial feature extraction  

NASA Astrophysics Data System (ADS)

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

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

2006-02-01

137

2D electromagnetic modelling of superconductors  

NASA Astrophysics Data System (ADS)

Some issues concerning the numerical analysis of superconductors are discussed and a novel approach to 2D modelling is proposed. Both axial and translational symmetric as well as current driven and voltage driven systems are examined in detail. The E-J power law is chosen instead of the critical state model as a constitutive relation of the material and the need to modify this relation in order to account for the normal state transition at high currents is discussed. A linear space reconstruction of the current density by means of nodal shape functions is used in order to build the finite dimensional model. A method to relax the tangential continuity of the current density, which is inherent to the discretization method used, is discussed. The performance of the proposed approach, both in terms of current distribution and AC loss, is evaluated with reference to some cases of practical interest involving composite materials. The role of the electric field as a natural state variable for superconducting problems is also pointed out. The use of the method as an alternative to the circuit approach or edge elements for modelling the superconductors is finally discussed.

Morandi, Antonio

2012-10-01

138

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

139

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.

140

Geometry Formulas and Facts  

NSDL National Science Digital Library

Rewritten and updated excerpts from the 30th Edition of the CRC Standard Mathematical Tables and Formulas. Covers all of geometry, minus differential geometry. Very complete collection of definitions, formulas, tables and diagrams, divided into two- and three- dimensional geometry, and further into 16 subdivisions such as transformations, polygons, coordinate systems, isometries, polyhedra and spheres.

Levy, Silvio

2007-12-07

141

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

142

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

143

Single Transistor Digital Logic Circuits based on Gate-controlled 2D-2D Resonant Tunneling  

NASA Astrophysics Data System (ADS)

We have fabricated a new quantum device, the double electron layer tunneling transistor (DELTT),(J. A. Simmons et al., 1998 March Meeting abstract.) in an MBE-grown highly density-imbalanced AlGaAs/GaAs double quantum well heterostructure for higher operating temperature. Unlike other resonant tunneling devices, the DELTT is implemented in planar configuration, enabling ease in fabrication. It operates based on 2D-2D resonant tunneling, yielding strong negative differential resistance (NDR) in its source-drain I-V, which can be controlled by surface Schottky gate. we illustrate the multifunctionality of a single DELTT at 77K by demonstrating digital logic circuits such as XOR and NAND gates. These circuits use considerably fewer transistors than their conventional counterparts.

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

1998-03-01

144

The 2D Rydberg series in Al I  

NASA Technical Reports Server (NTRS)

High-quality ab initio electronic structure calculations have been performed on the 2D Rydberg series in Al I. The configuration 3s3p2(2D) is shown to contribute substantially to the lowest four 2D Rydberg states. The same configuration also contributes substantially to a 2D state embedded in the ionization continuum. Computed oscillator strengths for the first six members of the 2D Rydberg transitions are given: these should be of substantially higher accuracy than currently available values.

Taylor, Peter R.; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.

1988-01-01

145

The 2D Rydberg series in Al I  

NASA Technical Reports Server (NTRS)

High quality ab initio electonic structure calculations were performed on the 2D Rydberg series in Al I. The configuration 3s3p2(2D) is shown to contribute substantially to the lowest four 2D Rydberg states. The same configuration also contributes substantially to a 2D state embedded in the ionization continuum. Computed oscillator strengths for the first six members of the 2D Rydberg transitions are given: these should be of substantially high accuracy than currently available values.

Taylor, Peter R.; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.

1987-01-01

146

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

PubMed Central

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.

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

1993-01-01

147

Planar quantum transistor based on 2D-2D tunneling in double quantum well heterostructures  

NASA Astrophysics Data System (ADS)

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 flip-chip process, whereby submicron gating on opposite sides of semiconductor epitaxial layers as thin as 0.24 ?m 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 (~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.

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

1998-11-01

148

2D Geodynamic models of Microcontinent Formation  

NASA Astrophysics Data System (ADS)

Continental fragments (microcontinents and continental ribbons) are rifted-off blocks of relatively unthinned continental crust situated among the severely thinned crust of passive margins. The existence of these large crustal blocks would suggest that the passive margin containing them either underwent simultaneous differential rifting or multi-stage rifting in order to produce continental breakup and seafloor spreading in more than one location in the span of approximately 100 km. Also, because continental fragments do not occur on every passive margin, there must be something particular about the crust and/or lithosphere that led to the production of these features. Some proposed mechanisms for microcontinent and continental ribbon formation include (1) structural inheritance, (2) strain localization by serpentinized mantle or magmatic underplating, and (3) plume interaction with an active rift. Pre-existing weakness and inherited structural fabrics in typical continental crust from past tectonic events, such as varying rheology of accreted terranes and collisional suture zones, could be reactivated and serve as foci for deformation. The second theory is that strain is localized in certain regions by large amounts of weakened material that are either serpentinized mantle or mafic bodies underplating the thinned crust. Another possible process that could lead to continental fragment formation is magmatic influence of hot plume material that focuses in various regions, producing rifts in separate areas. The Jan Mayen and Seychelles microcontinents both have geological and plate reconstruction evidence to support the plume interaction theory. We use 2-D geodynamic experiments to assess the importance of structural inheritance, strain localization by regions of weakened mantle material, and contributions to rifting from plume material on producing crustal blocks surrounded by seafloor or thinned/hyperextended crust. Our preliminary results suggest that each of these three mechanisms, working alone, cannot produce concurrent or multi-stage differential thinning and continental break-up. We infer that multistage extension produced by a combination of these mechanisms could be necessary to produce microcontinents and continental ribbons.

Tetreault, Joya; Buiter, Susanne

2013-04-01

149

Quasar Clustering and Spacetime Geometry  

NASA Astrophysics Data System (ADS)

The non-Euclidean geometry of spacetime induces an anisotropy in the apparent correlation function of high-redshift objects, such as quasars, if redshifts and angles are converted to distances in ``naive'' Euclidean fashion. The degree of angular distortion depends on cosmological parameters, especially on the cosmological constant ?, so this effect can constrain ? independent of any assumptions about the evolution of luminosities, sizes, or clustering. We examine the prospects for distinguishing between low-density (?0 = 0.1-0.4) cosmological models with flat and open space geometry using the large quasar samples anticipated from the Two Degree Field Survey (2dF) and the Sloan Digital Sky Survey (SDSS). Along the way, we derive a number of results that are useful for studies of the quasar correlation function. In particular, we show that even these large quasar surveys are likely to reside in the ``sparse sampling'' regime for correlation function measurements, so that the statistical fluctuations in measurements are simply the Poisson fluctuations in the observed numbers of pairs. As a result, (1) one can devise a simple maximum likelihood scheme for estimating clustering parameters, (2) one can generate Monte Carlo realizations of correlation function measurements without specifying high-order correlation functions or creating artificial quasar distributions, and (3) for a fixed number of quasars, a deeper survey over a smaller area has greater statistical power than a shallow, large-area survey. If the quasar correlation length is equal to the value implied by recent (quite uncertain) estimates, then the 2dF and SDSS samples can provide clear discrimination between flat and open geometries for ?0 <= 0.2 but only marginal discrimination for ?0 = 0.4. Clear discrimination is possible for ?0 = 0.4 if the true quasar correlation length is a factor of 2 larger, and a high-density survey of 30,000 quasars in 200 deg2 would provide clear discrimination even for the lower correlation length. Detection of quasar clustering anisotropy would confirm the cosmological spacetime curvature that is a fundamental prediction of general relativity.

Popowski, Piotr A.; Weinberg, David H.; Ryden, Barbara S.; Osmer, Patrick S.

1998-05-01

150

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

151

Intact NKG2D-Independent Function of NK Cells Chronically Stimulated with the NKG2D Ligand Rae-1  

PubMed Central

Human tumors frequently express membrane-bound or soluble NK group 2, member D (NKG2D) ligands. This results in chronic engagement of NKG2D on the surfaces of NK and CD8+ T cells and rapid internalization of the receptor. Although it is well appreciated that this phenomenon impairs NKG2D-dependent function, careful analysis of NKG2D-independent functions in cells chronically stimulated through NKG2D is lacking. Using a mouse model of chronic NKG2D ligand expression, we show that constant exposure to NKG2D ligands does not functionally impair NK cells and CD8+ T cells in the context of viral infection.

Champsaur, Marine; Beilke, Joshua N.; Ogasawara, Kouetsu; Koszinowski, Ulrich H.; Jonjic, Stipan; Lanier, Lewis L.

2014-01-01

152

3-D Ray-tracing and 2-D Fokker-Planck simulations of radiofrequency application to tokamak plasmas  

SciTech Connect

A state of the art numerical tool has been developed to simulate the propagation and the absorption of coexisting different types of waves in a tokamak geometry. The code includes a numerical solution of the three-dimensional (R, Z, {phi}) toroidal wave equation for the electric field of the different waves in the WKBJ approximation. At each step of integration, the two-dimensional (v{sub (parallel} {sub sign)}, v{sub (perpendicular} {sub sign)}) Fokker-Planck equation is solved in the presence of quasilinear diffusion coefficients. The electron Landau damping of the waves is modeled taking into account the interaction of the wave electric fields with the quasilinearly modified distribution function. Consistently, the code calculates the radial profiles of non-inductively generated current densities, the transmitted power traces and the total power damping curves. Synergistic effects among the different type of waves (e.g., lower hybrid and ion Bernstein waves) are studied through the separation of the contributions of the single wave from the effects due to their coexistence. (c) 1999 American Institute of Physics.

Paoletti, F. [Columbia University, New York, New York (United States); Cardinali, A. [Associazione Euratom-ENEA sulla Fusione, Frascati, Rome, (Italy); Bernabei, S. [Plasma Physics Laboratory, Princeton, New Jersey (United States)

1999-09-20

153

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

SciTech Connect

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

A. Cardinali; F. Paoletti; S. Bernabei

1999-05-01

154

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

155

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.

156

SGEMP Geometry Effects  

Microsoft Academic Search

Self-consistent, fully dynamic computer calculations were performed using the recently developed arbitrary body-of-revolution code ABORC for complex geometries in SGEMP environments to test the validity of simplifying geometry assumptions previously made in the solutions of these problems. Assumptions such as simple geometry representations of complex bodies and separability of inside and outside problems are tested. Effects of gaps, interior electrical

A. J. Woods; E. P. Wenaas

1975-01-01

157

Developments in special geometry  

NASA Astrophysics Data System (ADS)

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

Mohaupt, Thomas; Vaughan, Owen

2012-02-01

158

Geometry and Physics Today  

NASA Astrophysics Data System (ADS)

Geometry,” in the sense of the classical differential geometry of smooth manifolds (CDG), is put under scrutiny from the point of view of Abstract Differential Geometry (ADG). We explore potential physical implications of viewing things under the light of ADG, especially matters concerning the “ gauge theories” of modern physics, when the latter are viewed (as they are actually regarded currently) as “ physical theories of a geometrical character.” Thence, “ physical geometry,” in connection with physical laws and the associated with them, within the background spacetime manifoldless context of ADG, “ differential” equations, are also being discussed.

Mallios, Anastasios

2006-08-01

159

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 Møller-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

160

Double Electron Layer Tunneling Transistor (DELTT) Based on Gate Control of 2D-2D Tunneling  

NASA Astrophysics Data System (ADS)

We report on the characteristics of a quantum tunneling transistor based on the gate-control of 2D-2D tunneling in an AlGaAs/GaAs double quantum well (DQW). footnoteJ. P. Eisenstein et al., Phys. Rev. B 44, 6511 (1991). Unlike previously proposed quantum tunneling transistors, the DELTT is entirely planar and thus does not require strict lithographic tolerances. The source and drain independently contact the top and bottom QWs, while a surface Schottky gate acts as the third terminal. At 1.5 K, DELTTs with low density (approximately 2 x 10^ 11 cm-2) in each well exhibit peak-to-valley ratios of 20:1 in their source drain I-V curve, and peak-to-background ratios of 50:1 in the small- signal source-drain conductance vs. gate voltage. The gate voltage strongly shifts the size and position of the resonance peak in the I-V. Higher density DELTTs with a built-in QW density difference of 6 x 10^11 cm-2 exhibit characteristics that are nearly as good at 77 K. Elsewhere(M. A. Blount et al., 1998 March Meeting abstract.) we describe use of the DELTT in bistable memory circuits.

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

1998-03-01

161

2D to 3D to 2D Dimensionality Crossovers in Thin BSCCO Films  

NASA Astrophysics Data System (ADS)

With increasing temperature the superfluid fraction in very thin BSCCO films undergoes a series of dimensionality crossovers. At low temperatures the strong anisotropy causes the thermal excitations to be 2D pancake-antipancake pairs in uncoupled layers. At higher temperatures where the c-axis correlation length becomes larger than a layer there is a crossover to 3D vortex loops. These are initially elliptical, but as the 3D Tc is approached they become more circular as the anisotropy scales away, as modeled by Shenoy and Chattopadhyay [1]. Close to Tc when the correlation length becomes comparable to the film thickness there is a further crossover to a 2D Kosterlitz-Thouless transition, with a drop of the superfluid fraction to zero at T_KT which can be of the order of 1 K below T_c. Good agreement with this model is found for experiments on thin BSCCO 2212 films [2]. 1. S. R. Shenoy and B. Chattopadhyay, Phys. Rev. B 51, 9129 (1995). 2. K. Osborn et al., cond-mat/0204417.

Williams, Gary A.

2003-03-01

162

Induction of CYP2D6 in pregnancy  

Microsoft Academic Search

Expression of the drug-metabolizing enzyme cytochrome P4502D6 (CYP2D6) is predominantly under genetic control, and enzyme-inducing drugs have little influence on its activity. We studied the activity of CYP2D6 during pregnancy. One hundred forty pregnant women were genotyped for CYP2D6. Seventeen of them (four poor metabolizers, seven heterozygous extensive metabolizers, and six extensive metabolizers) were phenotyped with dextromethorphan in late pregnancy

Mia Wadelius; Elisabeth Darj; Gunilla Frenne; Anders Rane

1997-01-01

163

Approximation of 2-D separable in denominator filters  

Microsoft Academic Search

After introducing a two-dimensional (2-D) model for the class of causal, recursive, and separable in denominator (CRSD) filters, a technique for approximating a given 2-D filter by a CRSD filter is presented. Also, a technique for 2-D CRSD model reduction is considered. Both the stability and minimality properties of the approximate model are explored. Some examples are also given to

BIJAN LASHGARI; LEONARD M. SILVERMAN; JEAN-FRANCOIS ABRAMATIC

1983-01-01

164

Advances in 1D and 2D thermoelectric materials  

Microsoft Academic Search

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

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

1999-01-01

165

Functions of C2D macrophage cells after adoptive transfer  

Microsoft Academic Search

Macrophage function depends on their in situ location. To test this hypothesis, we exam- ined functional changes of the C2D macrophage cell line after adoptive transfer. In vitro, C2D mac- rophages reside early in the macrophage lineage and show little functional activity. After in vivo i.p. culture, C2D macrophage cells switch their cyto- kine\\/chemokine profile from primarily Th2 cyto- kines

Betsey E. Potts; Stephen K. Chapes

2007-01-01

166

Interactive Geometry Dictionary: Areas in Geometry  

NSDL National Science Digital Library

The applets in this Interactive Geometry Dictionary (IGD) will allow students an opportunity to explore finding the area of some common shapes. The applets demonstrate how to find the area of a triangle using the area of a parallelogram, which in turn can be found using the area of a rectangle. This tool also supports the lesson "What's My Area" cataloged separately.

2011-01-01

167

2D-CELL: image processing software for extraction and analysis of 2-dimensional cellular structures  

NASA Astrophysics Data System (ADS)

2D-CELL is a software package for the processing and analyzing of photographic images of cellular structures in a largely interactive way. Starting from a binary digitized image, the programs extract the line network (skeleton) of the structure and determine the graph representation that best models it. Provision is made for manually correcting defects such as incorrect node positions or dangling bonds. Then a suitable algorithm retrieves polygonal contours which define individual cells — local boundary curvatures are neglected for simplicity. Using elementary analytical geometry relations, a range of metric and topological parameters describing the population are then computed, organized into statistical distributions and graphically displayed.

Righetti, F.; Telley, H.; Leibling, Th. M.; Mocellin, A.

1992-01-01

168

Solution of the field equations for 2-D electromagnetic direct implicit plasma simulation  

NASA Astrophysics Data System (ADS)

A direct implicit particle-in-cell (PIC) simulation model with full electromagnetic (EM) effects has been implemented in 2-D Cartesian geometry. The model, implemented with the D1 time differencing scheme, was first implemented in a 1-D electrostatic (ES) version to gain some experience with spatial differencing in forms suitable for extension to the full EM field in two dimensions. The implicit EM field solve is considerably different from the implicit ES code. The EM field calculation requires an inductive part as well as the electrostatic and the B field must be self-consistently advanced.

Hewett, D. W.; Langdon, A. B.

1985-01-01

169

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

170

Behavioral response of male white peach scale to the sex pheromone, (R,Z)-3,9,-dimethyl-6-isopropenyl-3,9-decadien-1-ol propionate and corresponding alcohol.  

PubMed

Males of the white peach scale,Pseudaulacaspis pentagona (Tar-gioni-Tozzetti), in Florida differ from this scale in France in their responses to putative pheromonal chemicals presented in a laboratory bioassay. Males from Florida were attracted to, and exhibited sexual (coputatory) behaviors at, the locus of evaporation of (R,Z)-3,9-dimethyl-6-isopropenyl-3,9-deca-dien-1-ol propionate (P) (previously identified from effluvia of Florida females). Addition of the corresponding primary alcohol (A) to the propionate did not alter the attraction of Florida males to the synthetic P and did not alter their sexual responses from those exhibited by males exposed to P alone. In contrast, the effluvia from French scales has been reported to contain P and A, and the alcohol has been reported in laboratory studies to be required to release sexual behavior in French males. This suggests that the conspecific status of the scale in Florida and France should be reexamined. Field trap baits with 2.5 ?g of a 1? 1 mixture of P and A captured significantly fewer Florida males than traps baited with 1.25 ?g of P alone, but traps similarly baited with 0.125 ?g of each material captured the same number of insects as traps baited with 0.125 ?g of P alone. PMID:24263591

McLaughlin, J R

1990-03-01

171

Modons in spherical geometry  

Microsoft Academic Search

Spherical geometry equivalent modons are derived in analytical form, together with the dispersion relationship that related the modon's frequency, spatial extent, and interior wavenumber. Improved kinematic agreement with atmospheric blocking patterns are achieved by equivalent modons in spherical geometry in virtue of increasing asymmetry as the geographic pole is approached. Numerical experiments demonstrating the robustness of spherical modons to background

Joseph J. Tribbia

1984-01-01

172

Noncommutative geometry and gravity  

Microsoft Academic Search

We study a deformation of infinitesimal diffeomorphisms of a smooth manifold. The deformation is based on a general twist. This leads to a differential geometry on a noncommutative algebra of functions whose product is a star product. The class of noncommutative spaces studied is very rich. Non-anticommutative superspaces are also briefly considered. The differential geometry developed is covariant under deformed

Paolo Aschieri; Marija Dimitrijevic; Frank Meyer; Julius Wess

2006-01-01

173

Lectures on Noncommutative Geometry  

Microsoft Academic Search

These Lectures are based on a course on noncommutative geometry given by the author in 2003 at the University of Chicago. The lectures contain some standard material, such as Poisson and Gerstenhaber algebras, deformations, Hochschild cohomology, Serre functors, etc. We also discuss many less known as well as some new results, in particular, noncommutative Chern-Weil theory, noncommutative symplectic geometry, noncommutative

Victor Ginzburg

2005-01-01

174

Geometry of multihadron production  

SciTech Connect

This summary talk only reviews a small sample of topics featured at this symposium: Introduction; The Geometry and Geography of Phase space; Space-Time Geometry and HBT; Multiplicities, Intermittency, Correlations; Disoriented Chiral Condensate; Deep Inelastic Scattering at HERA; and Other Contributions.

Bjorken, J.D.

1994-10-01

175

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

176

Expansion, geometry, and gravity  

Microsoft Academic Search

In general-relativistic cosmological models, the expansion history, matter content, and geometry are closely intertwined. In this brief paper, we clarify the distinction between the effects of geometry and expansion history on the luminosity distance. We show that the cubic correction to the Hubble law, measured recently with high-redshift supernovae, is the first cosmological measurement, apart from the cosmic microwave background,

Robert R. Caldwell; Marc Kamionkowski

2004-01-01

177

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

178

Want to Play Geometry?  

ERIC Educational Resources Information Center

Students enter the geometry classroom with a strong concept of fairness and a sense of what it means to "play by the rules," yet many students have difficulty understanding the postulates, or rules, of geometry and their implications. Although they may never have articulated the properties of an axiomatic system, they have gained a practical…

Kaufmann, Matthew L.; Bomer, Megan A.; Powell, Nancy Norem

2009-01-01

179

A 2D simple attenuation model for EM waves in human tissues: Comparison with a FDTD 3D simulator for UWB medical radar  

Microsoft Academic Search

This paper describes a simple 2D model for the propagation of electro-magnetic (EM) pulses in human tissues. To assess the reliability of using this model for fast attenuation evaluation of UWB radar pulses in the body, the model is compared with a well known 3D FDTD numeric simulator using a simple multilayer geometry. Results from the 2D model were found

G. Varotto; E. M. Staderini

2008-01-01

180

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

2014-02-01

181

Numerical solution of the radiation transport equation in disk geometry  

NASA Technical Reports Server (NTRS)

An efficient numerical method for solving the problem of radiation transport in a dusty medium with two dimensional (2-D) disk geometry is described. It is a generalization of the one-dimensional quasi-diffusion method in which the transport equation is cast in diffusion form and then solved as a boundary value problem. The method should be applicable to a variety of astronomical sources, the dynamics of which are angular-momentum dominated and hence not accurately treated by spherical geometry, e.g., protoplanetary nebulae, circumstellar disks, interstellar molecular clouds, accretion disks, and disk galaxies. The computational procedure and practical considerations for implementing the method are described in detail. To illustrate the effects of 2-D radiation transport, some model results (dust temperature distributions and IR flux spectra) for externally heated, interstellar dust clouds with spherically symmetric and disk geometry are compared.

Spagna, George F., Jr.; Leung, Chun Ming

1987-01-01

182

2D gravity, random surfaces and all that.  

National Technical Information Service (NTIS)

I review the recent progress in 2d gravity and discuss the new numerical simulations for 2d gravity and for random surfaces in d>2. The random surface theories of interest in d>2 have extrinsic curvature terms, and for a finite value of the extrinsic curv...

J. Ambjoern

1990-01-01

183

?-Filtered Reconstruction: 2D xray CT vs. 3D TCT  

Microsoft Academic Search

?-filtered reconstruction in 2D xray CT is compared and contrasted to 3D thermoacoustic tomography. The math is simpler in 3D than 2D and a simple example sheds light on early CT results indicating image quality loss in ?-filtered reconstruction.

SARAH K. PATCH

184

Tamoxifen and CYP2D6: A Contradiction of Data  

PubMed Central

Tamoxifen is an effective antiestrogen used in the treatment of hormone receptor–positive breast cancer. Bioconversion of tamoxifen to endoxifen, its most abundant active metabolite, is primarily dependent on the activity of cytochrome P450 2D6 (CYP2D6), which is highly polymorphic. Over 20 published studies have reported on the potential association between CYP2D6 polymorphism and tamoxifen treatment outcome, with highly inconsistent results. The purpose of this review is to explore differences among 17 independent studies to identify factors that may have contributed to the discrepant findings. This report discusses six putative factors that are grouped into two categories: (a) clinical management criteria: hormone receptor classification, menopausal status, and tamoxifen combination therapy; (b) pharmacologic criteria: genotyping comprehensiveness, CYP2D6 inhibitor coadministration, and tamoxifen adherence. Comparison of these factors between the positive and negative studies suggests that tamoxifen combination therapy, genotyping comprehensiveness, and CYP2D6 inhibitor coadministration may account for some of the contradictory results. Future association studies on the link between CYP2D6 genotype and tamoxifen treatment efficacy should account for combination therapy and CYP2D6 inhibition, and interrogate as many CYP2D6 alleles as possible.

Hertz, Daniel L.; McLeod, Howard L.

2012-01-01

185

2D Barcode and Augmented Reality Supported English Learning System  

Microsoft Academic Search

This study aims to construct a 2D barcode handheld augmented reality supported learning system called HELLO (handheld english language learning organization), to improve students' English level. The HELLO integrates the 2D barcodes, the Internet, augmented reality, mobile computing and database technologies. The proposed system consists of two subsystems: an English learning management system and a mobile learning tools system. A

Tsung-yu Liu; Tan-hsu Tan; Yu-ling Chu

2007-01-01

186

Spectral Characteristics of the 2dFGRS-NVSS Galaxies  

NASA Astrophysics Data System (ADS)

We have analysed the 2dF spectra of a sample of galaxies common to the 2dF Galaxy Redshift Survey (2dFGRS, Colless 1999) and the NRAO VLA Sky Survey (NVSS, Condon et al. 1998). Our sample comprises 88 galaxies selected by Sadler et al. (1999) from 30 2dFGRS fields observed in 1998. In this paper we discuss how this and future, much larger, samples of 2dFGRS-NVSS galaxies can be interpreted via analysis of those galaxies with strong narrow emission lines. Using diagnostic line ratio measurements, we confirm the majority of the eyeball classifications of Sadler et al. (1999), although many galaxies show evidence of being `composite' galaxies—mixtures of AGN plus starburst components.

Jackson, C. A.; Londish, D. M.

2000-12-01

187

The influence of courtyard geometry on air flow and thermal comfort: CFD and thermal comfort simulations  

Microsoft Academic Search

Courtyard and building geometry are crucial aspects to achieve efficient natural ventilation and indoor thermal comfort in a compact urban environment. In this paper, first, a comparison between different geometries of courtyards in terms of wind flow characteristics and indoor air speed is performed based on the validation of Computational Fluid Dynamics (CFD) simulations with 2D publis hed wind-tunnel experiments.

Abel Tablada; Bert Blocken; Jan Carmeliet; Frank De Troyer

2005-01-01

188

Inelastic scattering calculations in polyatomic systems using an ab initio intermolecular potential energy surface: The CO2* (0,0,1,0)+H2(D2) -->CO2(0,0,0,0)+H2(D2) systems  

Microsoft Academic Search

An ab initio computation of the energy transfer dynamics in the (CO2,H2) and (CO2,D2) systems has been carried out. The intermolecular potential energy hypersurface has been obtained from the results of ab initio SCF computations using extended Gaussian basis sets. The potential energy has been computed for 1053 different geometries. Previously formulated cubic spline fitting procedures are employed to effect

N. Sathyamurthy; L. M. Raff

1977-01-01

189

Inelastic scattering calculations in polyatomic systems using an abinitio intermolecular potential energy surface: The CO2* (0,0,1,0)+H2(D2) ?CO2(0,0,0,0)+H2(D2) systems  

Microsoft Academic Search

An abinitio computation of the energy transfer dynamics in the (CO2,H2) and (CO2,D2) systems has been carried out. The intermolecular potential energy hypersurface has been obtained from the results of abinitio SCF computations using extended Gaussian basis sets. The potential energy has been computed for 1053 different geometries. Previously formulated cubic spline fitting procedures are employed to effect surface interpolation

N. Sathyamurthyt; L. M. Raff

1977-01-01

190

Native American Geometry  

NSDL National Science Digital Library

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

Forum, Math; Hardaker, Chris

2000-01-01

191

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

192

Continuous Motion, Outdoor, 2 1\\/2D grid Map Generation using an Inexpensive Nodding 2-D Laser Rangefinder  

Microsoft Academic Search

This paper introduces a technique for creating 2 1\\/2D grid maps of unstructured, outdoor environments, while traveling at high speeds, using an inexpensive nodding 2-D laser rangefinder. The nodding mechanism allows the acquisition of multiple range data sets for terrain in front of the robot. While these multiple data sets alleviate some of the problems traditionally associated with laser rangefinders,

Gregory Broten; Jack Collier

2006-01-01

193

Efficient large-domain 2-D FEM solution of arbitrary waveguides using p-refinement on generalized quadrilaterals  

Microsoft Academic Search

An efficient and accurate large-domain higher order two-dimensional (2-D) Galerkin-type technique based on the finite-element method (FEM) is proposed for analysis of arbitrary electromagnetic waveguides. The geometry of a waveguide cross section is approximated by a mesh of large Lagrangian generalized curvilinear quadrilateral patches of arbitrary geometrical orders (large domains). The fields over the elements are approximated by a set

Milan M. Ilic ´; A. Z. Ilic; Branislav M. Notaros

2005-01-01

194

Integrating Transformation Geometry into Traditional High School Geometry.  

ERIC Educational Resources Information Center

Describes a geometry course that integrates transformation geometry into traditional high school geometry. Discussion of the scope and sequence of the course includes the topics of proof, congruence, translations, rotations, reflections, dilations, quadrilaterals, parallel lines, and similarity. (MDH)

Okolica, Steve; Macrina, Georgette

1992-01-01

195

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

196

Proof in Transformation Geometry  

ERIC Educational Resources Information Center

The first of three articles showing how inductively-obtained results in transformation geometry may be organized into a deductive system. This article discusses two approaches to enlargement (dilatation), one using coordinates and the other using synthetic methods. (MM)

Bell, A. W.

1971-01-01

197

Noncommutative Geometry and Physics  

SciTech Connect

In this very short essay we shall describe a 'spectral' point of view on geometry which allows to start taking into account the lessons from both renormalization and of general relativity. We shall first do that for renormalization and explain in rough outline the content of our recent collaborations with Dirk Kreimer and Matilde Marcolli leading to the universal Galois symmetry of renormalizable quantum field theories provided by the renormalization group in its cosmic Galois group incarnation. As far as general relativity is concerned, since the functional integral cannot be treated in the traditional perturbative manner, it relies heavily as a 'sum over geometries' on the chosen paradigm of geometric space. This will give us the occasion to discuss, in the light of noncommutative geometry, the issue of 'observables' in gravity and our joint work with Ali Chamseddine on the spectral action, with a first attempt to write down a functional integral on the space of noncommutative geometries.

Connes, Alain [College de France, 3, rue d'Ulm, Paris, F-75005 France (France)

2006-11-03

198

Noncommutative Geometry and Physics  

NASA Astrophysics Data System (ADS)

In this very short essay we shall describe a ``spectral'' point of view on geometry which allows to start taking into account the lessons from both renormalization and of general relativity. We shall first do that for renormalization and explain in rough outline the content of our recent collaborations with Dirk Kreimer and Matilde Marcolli leading to the universal Galois symmetry of renormalizable quantum field theories provided by the renormalization group in its cosmic Galois group incarnation. As far as general relativity is concerned, since the functional integral cannot be treated in the traditional perturbative manner, it relies heavily as a ``sum over geometries'' on the chosen paradigm of geometric space. This will give us the occasion to discuss, in the light of noncommutative geometry, the issue of ``observables'' in gravity and our joint work with Ali Chamseddine on the spectral action, with a first attempt to write down a functional integral on the space of noncommutative geometries.

Connes, Alain

2006-11-01

199

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

200

Discrete and Convex Geometry  

Microsoft Academic Search

\\u000a Mathematical research in Hungary started with geometry: with the work of the two Bolyais early in the 19th century. The father,\\u000a Farkas Bolyai, showed that equal area polygons are equidecomposable. The son, János Bolyai, laid down the foundations of non-Euclidean\\u000a geometry. The study of geometric objects has been continuing ever since. The present chapter of this book is devoted to

Imre Bárány

201

View-dependent geometry  

Microsoft Academic Search

When constructing 3D geometry for use in cel animation, the reference drawings of the object or character often contain various view-specific distortions, which cannot be captured with conventional 3D models. In this work we present a technique called View-Dependent Geometry, wherein a 3D model changes shape based on the direction it is viewed from. A view-dependent model consists of a

Paul Rademacher

1999-01-01

202

2D fluid simulation of RF inductive sources  

SciTech Connect

Inductive and other high density sources are of great interest to industry and are promised to be the next generation of plasma processing reactors. The two-dimensional (R-Z) electromagnetic code ZMR is being modified to include interactions between charged-particles and neutral species for modeling inductive sources self-consistently. Presently, the code models an argon plasma with momentum-transfer, excitation and ionization as electron-neutral reactions and scattering and charge-exchange for the ion-neutral reactions. The electrons and ions are treated as Maxwellian fluid species. In the zero electron inertia limit, the electron momentum equation is combined with a modified set of Maxwell`s equations to do the field advance. The numerical techniques used in ZMR relax the typical temporal and spatial constraints (e.g., {omega}{sub pc}{Delta}t < O(1), {lambda}De/{Delta}x < O(1), and c{Delta}t/{Delta}x < 1) allowing one to choose appropriate time-step to resolve only the frequencies of interest (e.g., {omega}{sub RF}{Delta}t < O(0.1)). Analytic boundary conditions are used to resolve the proper density profile without resolving the Debye sheaths. Density and power profiles will be shown over a wide range of neutral pressures and input powers.

Hewett, D.W.; Dipeso, G.J.; Vahedi, V.; Rognlien, T.D. [Lawrence Livermore National Lab., CA (United States)

1993-12-01

203

An Evaluation of Multimodal 2D+3D Face Biometrics  

Microsoft Academic Search

Abstract—We report on the largest experimental,study to date in multimodal 2D+3D face recognition, involving 198 persons in the gallery and either 198 or 670 time-lapse probe images. PCA-based methods,are used separately for each modality and match,scores in the separate,face spaces,are combined,for multimodal,recognition. Major conclusions,are: 1) 2D and 3D have similar recognition performance when considered individually, 2) combining 2D and 3D

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

2005-01-01

204

Cluster algebras in scattering amplitudes with special 2D kinematics  

NASA Astrophysics Data System (ADS)

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

Torres, Marcus A. C.

2014-02-01

205

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

206

Almost but not quite 2D, Non-linear Bayesian Inversion of CSEM Data  

NASA Astrophysics Data System (ADS)

The geophysical inverse problem can be elegantly stated in a Bayesian framework where a probability distribution can be viewed as a statement of information regarding a random variable. After all, the goal of geophysical inversion is to provide information on the random variables of interest - physical properties of the earth's subsurface. However, though it may be simple to postulate, a practical difficulty of fully non-linear Bayesian inversion is the computer time required to adequately sample the model space and extract the information we seek. As a consequence, in geophysical problems where evaluation of a full 2D/3D forward model is computationally expensive, such as marine controlled source electromagnetic (CSEM) mapping of the resistivity of seafloor oil and gas reservoirs, Bayesian studies have largely been conducted with 1D forward models. While the 1D approximation is indeed appropriate for exploration targets with planar geometry and geological stratification, it only provides a limited, site-specific idea of uncertainty in resistivity with depth. In this work, we extend our fully non-linear 1D Bayesian inversion to a 2D model framework, without requiring the usual regularization of model resistivities in the horizontal or vertical directions used to stabilize quasi-2D inversions. In our approach, we use the reversible jump Markov-chain Monte-Carlo (RJ-MCMC) or trans-dimensional method and parameterize the subsurface in a 2D plane with Voronoi cells. The method is trans-dimensional in that the number of cells required to parameterize the subsurface is variable, and the cells dynamically move around and multiply or combine as demanded by the data being inverted. This approach allows us to expand our uncertainty analysis of resistivity at depth to more than a single site location, allowing for interactions between model resistivities at different horizontal locations along a traverse over an exploration target. While the model is parameterized in 2D, we efficiently evaluate the forward response using 1D profiles extracted from the model at the common-midpoints of the EM source-receiver pairs. Since the 1D approximation is locally valid at different midpoint locations, the computation time is far lower than is required by a full 2D or 3D simulation. We have applied this method to both synthetic and real CSEM survey data from the Scarborough gas field on the Northwest shelf of Australia, resulting in a spatially variable quantification of resistivity and its uncertainty in 2D. This Bayesian approach results in a large database of 2D models that comprise a posterior probability distribution, which we can subset to test various hypotheses about the range of model structures compatible with the data. For example, we can subset the model distributions to examine the hypothesis that a resistive reservoir extends overs a certain spatial extent. Depending on how this conditions other parts of the model space, light can be shed on the geological viability of the hypothesis. Since tackling spatially variable uncertainty and trade-offs in 2D and 3D is a challenging research problem, the insights gained from this work may prove valuable for subsequent full 2D and 3D Bayesian inversions.

Ray, A.; Key, K.; Bodin, T.

2013-12-01

207

Efficient framework for deformable 2D-3D registration  

NASA Astrophysics Data System (ADS)

Using 2D-3D registration it is possible to extract the body transformation between the coordinate systems of X-ray and volumetric CT images. Our initial motivation is the improvement of accuracy of external beam radiation therapy, an effective method for treating cancer, where CT data play a central role in radiation treatment planning. Rigid body transformation is used to compute the correct patient setup. The drawback of such approaches is that the rigidity assumption on the imaged object is not valid for most of the patient cases, mainly due to respiratory motion. In the present work, we address this limitation by proposing a flexible framework for deformable 2D-3D registration consisting of a learning phase incorporating 4D CT data sets and hardware accelerated free form DRR generation, 2D motion computation, and 2D-3D back projection.

Fluck, Oliver; Aharon, Shmuel; Khamene, Ali

2008-04-01

208

Geometry of PDE's. IV  

NASA Astrophysics Data System (ADS)

Following our previous results on this subject [R.P. Agarwal, A. Prástaro, Geometry of PDE's. III(I): Webs on PDE's and integral bordism groups. The general theory, Adv. Math. Sci. Appl. 17 (2007) 239-266; R.P. Agarwal, A. Prástaro, Geometry of PDE's. III(II): Webs on PDE's and integral bordism groups. Applications to Riemannian geometry PDE's, Adv. Math. Sci. Appl. 17 (2007) 267-285; A. Prástaro, Geometry of PDE's and Mechanics, World Scientific, Singapore, 1996; A. Prástaro, Quantum and integral (co)bordism in partial differential equations, Acta Appl. Math. (5) (3) (1998) 243-302; A. Prástaro, (Co)bordism groups in PDE's, Acta Appl. Math. 59 (2) (1999) 111-201; A. Prástaro, Quantized Partial Differential Equations, World Scientific Publishing Co, Singapore, 2004, 500 pp.; A. Prástaro, Geometry of PDE's. I: Integral bordism groups in PDE's, J. Math. Anal. Appl. 319 (2006) 547-566; A. Prástaro, Geometry of PDE's. II: Variational PDE's and integral bordism groups, J. Math. Anal. Appl. 321 (2006) 930-948; A. Prástaro, Th.M. Rassias, Ulam stability in geometry of PDE's, Nonlinear Funct. Anal. Appl. 8 (2) (2003) 259-278; I. Stakgold, Boundary Value Problems of Mathematical Physics, I, The MacMillan Company, New York, 1967; I. Stakgold, Boundary Value Problems of Mathematical Physics, II, Collier-MacMillan, Canada, Ltd, Toronto, Ontario, 1968], integral bordism groups of the Navier-Stokes equation are calculated for smooth, singular and weak solutions, respectively. Then a characterization of global solutions is made on this ground. Enough conditions to assure existence of global smooth solutions are given and related to nullity of integral characteristic numbers of the boundaries. Stability of global solutions are related to some characteristic numbers of the space-like Cauchy dataE Global solutions of variational problems constrained by (NS) are classified by means of suitable integral bordism groups too.

Prástaro, Agostino

2008-02-01

209

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

210

Dynamic unfolding of multilayers: 2D numerical approach and application to turbidites in SW Portugal  

NASA Astrophysics Data System (ADS)

Numerical algorithms for two-dimensional (2D) ductile multilayer folding are used (1) to unfold synthetically generated multilayer folds and natural multilayer folds in turbidites on the SW coast of Portugal and (2) to test how 2D ductile multilayer folding may generate collapsed hinges. A series of dynamic retro-deformation experiments with different viscosity ratios, rheological flow laws, boundary conditions and initial geometries were able to restore digitized, natural multilayer folds to flat layers, except one particular collapsed hinge with closed limbs (i.e. no matrix material left between limbs). Consistently, 2D forward simulations of ductile multilayer folding produced always omega-shaped hinges with matrix material remaining stuffed between limbs. These numerical results suggested that 2D reverse ductile unfolding cannot retro-deform the fully closed, collapsed hinge. Having observed that one limb of this collapsed fold is ruptured, with a measured gap of about 4.9 m, additional calculations were made with implementation of this amount of stretching. Results were not more satisfactory. Since omega-shaped folds exist in other places in the field area, we concluded that in this specific case shales were likely squeezed out from the hinge in the third dimension, parallel to the fold axis. Dynamic retro-deformations indicate that the effective viscosity ratio between inter-layered quartzwackes and shales was between 25 and 100 during folding. They further point out where 3D flow and possibly fracturing were effective during folding. This work demonstrates the constructive feedback between numerical tests and field data and that dynamic retro-deformation offers rheological constraints that geometric retro-deformation of geological sections cannot provide.

Lechmann, S. M.; Schmalholz, S. M.; Burg, J.-P.; Marques, F. O.

2010-10-01

211

Phylogenetic tree construction based on 2D graphical representation  

NASA Astrophysics Data System (ADS)

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

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

2006-04-01

212

Codeine Intoxication Associated with Ultrarapid CYP2D6 Metabolism  

Microsoft Academic Search

Life-threatening opioid intoxication developed in a patient after he was given small doses of codeine for the treatment of a cough associated with bilateral pneumonia. Co- deine is bioactivated by CYP2D6 into morphine, which then undergoes further glucu- ronidation. CYP2D6 genotyping showed that the patient had three or more functional alleles, a finding consistent with ultrarapid metabolism of codeine. We

Yvan Gasche; Youssef Daali; Marc Fathi; Alberto Chiappe; Silvia Cottini; Pierre Dayer; Jules Desmeules

2004-01-01

213

Superquadric-based reconstruction from 2D images  

Microsoft Academic Search

An approach for superquadric-based reconstruction from 2D images is developed, which computes and reconstructs the parametric models of the VE objects from the 2D images of the counterpart real objects. The superquadric-based hierarchical description as the universal parametric description of the 3D objects is proposed. On one hand, according to the complexity of the real objects, the superquadric curves and

Weibin Liu; Chao Zhang; Baozong Yuan

2002-01-01

214

ISAR Target 2D Images Pre-processing in ATR  

Microsoft Academic Search

The recognition performance can be enhanced using the ISAR target 2D image pre-processed. The image consists of many scatters. The image with holes is disadvantageous for extracting features in automatic target recognition (ATR). An approach of ISAR target 2D image pre-processing is proposed. It contains suppressing the interferential stripes, connecting the scatters and normalizing the mass center. The smoothed image

Xinggan Zhang; Yechao Bai

2009-01-01

215

General formulas for 2-D leaky-wave antennas  

Microsoft Academic Search

General formulas for a two-dimensional (2-D) leaky-wave antenna (LWA) are obtained, which are applicable to any general class of 2-D leaky-wave antenna that consists of a partially reflecting surface that is mounted on top of a grounded substrate, and excited by a simple source. Closed-form expressions are obtained for the radiated fields, the field peak values in the E- and

Tianxia Zhao; David R. Jackson; Jeffery T. Williams; Arthur A. Oliner

2005-01-01

216

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

217

Colloidal dipolar interactions in 2D smectic-C films  

Microsoft Academic Search

:   We use a two-dimensional (2D) elastic free energy to calculate the effective interaction between two circular disks immersed\\u000a in smectic-C films. For strong homeotropic anchoring, the distortion of the director field caused by the disks generates topological\\u000a defects that induce an effective interaction between the disks. We use finite elements, with adaptive meshing, to minimize\\u000a the 2D elastic free

P. Patrício; M. Tasinkevych; M. M. Telo da Gama

2002-01-01

218

Atmospheric radiative transfer through global arrays of 2D clouds  

Microsoft Academic Search

Shortwave and longwave 2D radiative transfer calculations were performed using Monte Carlo radiative transfer models and output from a global climate model (GCM) that employed, in each of its columns, a 2D cloud system-resolving model (CSRM) with a horizontal grid-spacing ?x of 4 km. CSRM output were sampled every 9 hours for December 2000. Radiative fluxes were averaged to the

J. N. S. Cole; H. W. Barker; W. O'Hirok; E. E. Clothiaux; M. F. Khairoutdinov; D. A. Randall

2005-01-01

219

Atmospheric radiative transfer through global arrays of 2D clouds  

Microsoft Academic Search

Shortwave and longwave 2D radiative transfer calculations were performed using Monte Carlo radiative transfer models and output from a global climate model (GCM) that employed, in each of its columns, a 2D cloud system-resolving model (CSRM) with a horizontal grid-spacing Deltax of 4 km. CSRM output were sampled every 9 hours for December 2000. Radiative fluxes were averaged to the

J. N. S. Cole; H. W. Barker; W. O'Hirok; E. E. Clothiaux; M. F. Khairoutdinov; D. A. Randall

2005-01-01

220

2D:4D and Sexually Dimorphic Facial Characteristics  

Microsoft Academic Search

The second-to-fourth-digit ratio (2D:4D) may be related to prenatal testosterone and estrogen levels and pu- bertal face growth. Several studies have recently provided evidence that 2D:4D is associated with other-rated facial masculinity and dominance, but not with facialmetric mea- sures of masculinity. We found that localized face shape differences, shown here to be sexually dimorphic and related to ratings of

Robert P. Burriss; Anthony C. Little; Emma C. Nelson

2006-01-01

221

Microstructural Fluctuations in 2D Dusty Plasma Liquids  

Microsoft Academic Search

We address structural fluctuations in a cold 2D dusty plasma liquid which is self-organized through the strong Coulomb coupling of the negatively charged micro-meter sized dust particles suspending in weakly ionized discharges. The 2D liquids consist of triangular type ordered domains surrounded by defect clusters, which can be reorganized through avalanche type hopping under the interplay of strong Coulomb coupling

Lin I; Yu-Hsuan Huang; Lee-Wen Teng

2007-01-01

222

The linear ? method for 2-D elastodynamic BE analysis  

Microsoft Academic Search

A linear ? method is used here to solve 2-D elastodynamic problems. Linear time and space interpolation functions are used,\\u000a and expressions for the computation of stresses at internal points by means of appropriate integral equations are presented.\\u000a When compared with the standard point collocation procedure, the linear ? method is more stable for 2-D elastodynamic problems,\\u000a with an equivalent

G. Yu; W. J. Mansur; J. A. M. Carrer

1999-01-01

223

A 2D-3D Hybrid Approach to Video Stabilization  

Microsoft Academic Search

In this paper, we introduce a novel 2D-3D hybrid video stabilization method which combines virtues of 2D and 3D video stabilization methods in one routine. It attempts to achieve high-quality camera motions and to retain full frame coherence in each frame, at while, ensure that local regions undergo a similarity transformation. We solve the stabilization problem by integrating 3D and

Zhiyong Huang; Fazhi He; Xiantao Cai; Yuan Chen; Xiao Chen

2011-01-01

224

2-D Walsh coding for robust digital image watermarking  

Microsoft Academic Search

One-dimensional (1D) Walsh coding have previously been proposed to improve the robustness of digital image watermarking techniques. In this paper, it is proposed to use two-dimensional (2D) Walsh coding to achieve further improvements in robustness. In the proposed method, Walsh functions are used to perform 2D coding of the watermark before embedding it in the original image. Simulation results, using

A. B. Sewaif; M. Al-Mualla; H. Al-Ahmad

2004-01-01

225

Automatic Contour Extraction from 2D Neuron Images  

Microsoft Academic Search

This work describes a novel methodology for automatic contour extraction from 2D im- ages of 3D neurons (e.g. camera lucida images and other types of 2D microscopy). Most contour-based shape analysis methods can not be used to characterize such cells because of overlaps between neuronal processes. The proposed framework is specifically aimed at the problem of contour following even in

Jorge J. G. Leandro; Roberto M. Cesar Jr.; Luciano Da Fontoura Costa

2008-01-01

226

Automatic contour extraction from 2D neuron images  

Microsoft Academic Search

This work describes a novel methodology for automatic contour extraction from 2D images of 3D neurons (e.g. camera lucida images and other types of 2D microscopy). Most contour-based shape analysis methods cannot be used to characterize such cells because of overlaps between neuronal processes. The proposed framework is specifically aimed at the problem of contour following even in presence of

J. J. G. Leandro; R. M. Cesar-Jr; L. da F. Costa

2009-01-01

227

Technical Report - Automatic Contour Extraction from 2D Neuron Images  

Microsoft Academic Search

This work describes a novel methodology for automatic contour extraction from 2D images of 3D neurons (e.g. camera lucida images and other types of 2D microscopy). Most contour-based shape analysis methods can not be used to characterize such cells because of overlaps between neuronal processes. The proposed framework is specifically aimed at the problem of contour following even in presence

J. J. G. Leandro; R. M. Cesar Jr; L. da F. Costa

2008-01-01

228

Technical Report - Automatic Contour Extraction from 2D Neuron Images  

Microsoft Academic Search

This work describes a novel methodology for automatic contour extraction from\\u000a2D images of 3D neurons (e.g. camera lucida images and other types of 2D\\u000amicroscopy). Most contour-based shape analysis methods can not be used to\\u000acharacterize such cells because of overlaps between neuronal processes. The\\u000aproposed framework is specifically aimed at the problem of contour following\\u000aeven in presence

J. J. G. Leandro; R. M. Cesar-Jr; F. Costa

2008-01-01

229

2dF Galaxy Redshift Survey. II. (Sadler+, 2002)  

NASA Astrophysics Data System (ADS)

We have cross-matched the 1.4-GHz NRAO VLA Sky Survey (NVSS, Condon 1998, Cat. ) with the first 210 fields observed in the 2dF Galaxy Redshift Survey (2dFGRS, Colless, 2001, Cat. ), covering an effective area of 325{deg}2 (about 20 per cent of the final 2dFGRS area). This yields a set of optical spectra of 912 candidate NVSS counterparts, of which we identify 757 as genuine radio identifications - the largest and most homogeneous set of radio source spectra ever obtained. The 2dFGRS radio sources span the redshift range z=0.005 to 0.438, and are a mixture of active galaxies (60 per cent) and star-forming galaxies (40 per cent). About 25 per cent of the 2dFGRS radio sources are spatially resolved by NVSS, and the sample includes three giant radio galaxies with projected linear size greater than 1 Mpc. The high quality of the 2dF spectra means we can usually distinguish unambiguously between AGN and star-forming galaxies. We make a new determination of the local radio luminosity function at 1.4 GHz for both active and star-forming galaxies, and derive a local star formation density of 0.022+/-0.004M{sun}/yr/Mpc3 (H0=50km/s/Mpc) (5 data files).

Sadler, E. M.; Jackson, C. A.; Cannon, R. D.; McIntyre, V. J.; Murphy, T.; Bland-Hawthorn, J.; Bridges, T.; Cole, S.; Colless, M.; Collins, C.; Couch, W.; Dalton, G.; de Propris, R.; Driver, S. P.; Efstathiou, G.; Ellis, R. S.; Frenk, C. S.; Glazebrook, K.; Lahav, O.; Lewis, I.; Lumsden, S.; Maddox, S.; Madgwick, D.; Norberg, P.; Peacock, J. A.; Peterson, B. A.; Sutherland, W.; Taylor, K.

2002-02-01

230

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

231

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

NASA Astrophysics Data System (ADS)

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

Liao, Jie; Gerya, Taras

2014-05-01

232

Students Discovering Spherical Geometry Using Dynamic Geometry Software  

ERIC Educational Resources Information Center

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

Guven, Bulent; Karatas, Ilhan

2009-01-01

233

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

234

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 20–25% 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

235

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

236

2D whispering gallery vs. 3D whispering cave  

NASA Astrophysics Data System (ADS)

Lord Rayleigh's 2 dimensional (2D) whispering gallery mode (WGM) is based upon 2D total internal reflection (TIR) while 3D whispering cave mode (WCM) is based upon 3D TIR. 3D WCM is however irreducible to 2D WGM: The 2D WGM is confined to a thin microdisk with a cylindrical symmetry solvable via Bessel function analysis while the 3D WCM is confined to a virtual toroid with a circular helix symmetry not reducible to a simple 2D symmetry. The 3D WCM laser is surface-normal dominant and has no in-plane resonance while the 2D WGM laser is in-plane dominant. Apart from the regular 2D WGM, the 3D WCM's major polarization state favors a strong carrier-photon coupling for the carriers in the planar quantum wells, such that the powerful transient coupling generates photonic quantum rings (PQRs), or concentric quantum rings with a half-wavelength pitch of imminently recombinant carriers, i.e., a photonic quantum corral effect. This feature is responsible for the low threshold currents and thermally stable spectra, which opens the way for easy optical mega-pixel ('Omega') chip fabrications. For the GaAs device size less than 1 ?m, the increasing intermode spacing leads to a single eigenmode PQR laser with a record low threshold current of 300 nA.. Moreover PQR 'holes', or microholes in the quantum well plane, give rise to an unusual 'convex' WCM laser via gain guiding effects. Mega-pixel PQR 'hole' laser chips are easier to fabricate than PQR 'mesa' chips, and both will be useful for optoelectronic VLSI, ITS, and biocell sorting.

Kwon, O'Dae

2008-02-01

237

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

238

The Decreased in Vivo Clearance of CYP2D6 Substrates by CYP2D6*10 Might Be Caused Not Only by the Low-Expression but Also by Low Affinity of CYP2D6  

Microsoft Academic Search

CYP2D6 exhibits genetic polymorphism with interindividual differences in metabolic activity. We have found a significant influence on the pharmacokinetics of venlafaxine by the CYP2D6*10 allele in a Japanese population. CYP2D6.10, which is translated from CYP2D6*10, has two amino acid substitutions: Pro34 ? Ser and Ser486 ? Thr. In this study, CYP2D6.10 was expressed in Saccharomyces cerevisiae and its catalytic activity

Tsuyoshi Fukuda; Yuko Nishida; Susumu Imaoka; Toyoko Hiroi; Masakazu Naohara; Yoshihiko Funae; Junichi Azuma

2000-01-01

239

2D/3D switchable LCD monitor with chromatic separation  

NASA Astrophysics Data System (ADS)

The 2D/3D switchable LCD stereoscopic display is based on the method of chromatic stereoscopic frame separation that occurs between the left and right eye with the use of two spectrally independent backlight sources with primary color sets RGBLeft and RGBRigth. Semiconductor lasers and/or LEDs with narrow band spectral filters could be used as backlight sources. In a 3D mode, the RGB sources illuminate alternatively and synchronously with the alternative displaying of stereo pair frames. Glasses with chromatic filters are used for watching in 3D mode and separate light from two RGB sources between the eyes of the viewer and in that way separate stereoscopic frames. In a 2D mode, any one of the RGB sources would work. In this case, the display looks like an ordinary display. Two RGB sources could be used for color enhancement in 2D mode. The quality of the images in 3D mode is the same as in 2D. Frame frequency is two times less in 3D mode as compared to 2D. The suggested method competes with two known methods for LCD that use glasses: "Shutter-Glasses Method" and "Polarization Method." It has certain advantages: image quality and stereo channel separation are independent from viewing angle or head tilt of viewer, and there are no active components in the glasses.

Gaskevich, Evgeny B.

2010-02-01

240

‘Graphenization’ of 2D simple monatomic liquids  

NASA Astrophysics Data System (ADS)

We present molecular dynamics (MD) simulations of the formation of 2D materials with a honeycomb structure from 2D simple monatomic liquids with honeycomb interaction potential (Rechtsman et al 2005 Phys. Rev. Lett. 95 228301). Models are observed by cooling from the melt at various cooling rates. Thermodynamics of the phase transitions is analyzed in detail. Depending on the cooling rate, amorphous or crystalline honeycomb structures have been found. Structural properties of the crystalline honeycomb structure are studied via radial distribution function (RDF), coordination number and ring distribution, including 2D visualization of the atomic configurations. We find evidence for the existence of polycrystalline honeycomb structures and new structural defects, not previously reported. The atomic mechanism that forms the solid phase of a honeycomb structure from the liquid state has been analyzed by monitoring the spatio-temporal arrangement of atoms in 6-fold rings and/or atoms with the coordination number Z=3 , occurring upon cooling from the melt. Since knowledge of how real 2D solids with honeycomb structures form from the vapor or liquid phase is still completely lacking, our simulations highlight the situation and give a deeper understanding of the structure and thermodynamics of real 2D materials such as graphene, silicene, germanene, etc.

Van Hoang, Vo

2014-05-01

241

Cancer immunotherapy using NKG2D and DNAM-1 systems.  

PubMed

Although tumor antigen-specific immunotherapy, such as dendritic cell vaccine, has recently emerged as a promising clinical approach, one limitation of tumor antigen- and T-cell receptor (TcR)-specific immunotherapy is antigen-specific inhibition by antigen-specific regulatory T-cell and myeloid suppressor cells. Therefore, immunotherapy using a TcR-independent mechanism may be an alternative immunotherapeutic strategy. NKG2D (natural killer, group 2, member D) and DNAX accessory molecule-1 (DNAM-1) are both activated receptors that are strongly expressed on T-cells, ??T-cells, and NK cells. Therefore, the expression of ligands for NKG2D and DNAM-1 on tumor cells plays an important role in tumor opsonization by immune effector cell targeting. Various modulatory methods for up-regulating NKG2D and DNAM-1-ligands have been reported, and included chemotherapeutic agents and hyperthermia. Although there are many obstacles to the utilization of NKG2D and DNAM-1 for cancer therapy, combined treatments using immune cell therapy and chemotherapy that take advantage of NKG2D and DNAM-1 may be an ideal approach. PMID:22641658

Morisaki, Takashi; Onishi, Hideya; Katano, Mitsuo

2012-06-01

242

Tryptamine: a possible endogenous substrate for CYP2D6.  

PubMed

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

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

1997-04-01

243

'Graphenization' of 2D simple monatomic liquids.  

PubMed

We present molecular dynamics (MD) simulations of the formation of 2D materials with a honeycomb structure from 2D simple monatomic liquids with honeycomb interaction potential (Rechtsman et al 2005 Phys. Rev. Lett. 95 228301). Models are observed by cooling from the melt at various cooling rates. Thermodynamics of the phase transitions is analyzed in detail. Depending on the cooling rate, amorphous or crystalline honeycomb structures have been found. Structural properties of the crystalline honeycomb structure are studied via radial distribution function (RDF), coordination number and ring distribution, including 2D visualization of the atomic configurations. We find evidence for the existence of polycrystalline honeycomb structures and new structural defects, not previously reported. The atomic mechanism that forms the solid phase of a honeycomb structure from the liquid state has been analyzed by monitoring the spatio-temporal arrangement of atoms in 6-fold rings and/or atoms with the coordination number [Formula: see text], occurring upon cooling from the melt. Since knowledge of how real 2D solids with honeycomb structures form from the vapor or liquid phase is still completely lacking, our simulations highlight the situation and give a deeper understanding of the structure and thermodynamics of real 2D materials such as graphene, silicene, germanene, etc. PMID:24769527

Hoang, Vo Van

2014-05-21

244

GEOMETRY, TENTATIVE GUIDES.  

ERIC Educational Resources Information Center

PRESENTED IS A FUSED COURSE IN PLANE, SOLID, AND COORDINATE GEOMETRY. ELEMENTARY SET THEORY, LOGIC, AND THE PRINCIPLE OF SEPARATION PROVIDE UNIFYING THREADS THROUGHOUT THE TEXT. THE TWO CURRICULUM GUIDES HAVE BEEN PREPARED FOR USE WITH TWO DIFFERENT TEXTS. EITHER CURRICULUM GUIDE MAY BE USED DEPENDING UPON THE CHOICE OF THE TEACHER AND THE NEEDS…

KLIER, KATHERINE M.

245

Seminar in Geometry  

NSDL National Science Digital Library

This course involves students taking turn giving lectures on geometry topics. Subjects such as Gauss maps, minimal surfaces and manifolds and geodesics were covered in the lectures. Course materials include lecture notes as well as student projects and examples. MIT presents OpenCourseWare as free educational material online. No registration or enrollment is required to use the materials.

Carberry, Emma Elizabeth, 1974-

2010-12-27

246

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, Università di Bologna and INFN Sezione di Bologna, Via Irnerio, 46-I-40126 Bologna (Italy)] [Dipartimento di Fisica, Università di Bologna and INFN Sezione di Bologna, Via Irnerio, 46-I-40126 Bologna (Italy); Limpouch, J.; Klimo, O.; Psikal, J. [Institute of Physics of the ASCR, ELI-Beamlines/HiLASE project, Na Slovance 2, 18221 Prague, Czech Republic and Czech Technical University in Prague, FNSPE, Brehova 7, 115 19 Prague (Czech Republic)] [Institute of Physics of the ASCR, ELI-Beamlines/HiLASE project, Na Slovance 2, 18221 Prague, Czech Republic and Czech Technical University in Prague, FNSPE, Brehova 7, 115 19 Prague (Czech Republic); Antici, P. [Dipartimento di Energetica ed INFM, Università di Roma, La Sapienza, 00165 Roma (Italy)] [Dipartimento di Energetica ed INFM, Università di Roma, La Sapienza, 00165 Roma (Italy); Margarone, D.; Korn, G. [Institute of Physics of the ASCR, ELI-Beamlines/HiLASE project, Na Slovance 2, 18221 Prague (Czech Republic)] [Institute of Physics of the ASCR, ELI-Beamlines/HiLASE project, Na Slovance 2, 18221 Prague (Czech Republic)

2013-07-26

247

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

248

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.

Atiyah, Michael; Dijkgraaf, Robbert; Hitchin, Nigel

2010-01-01

249

in Noncommutative Geometry  

Microsoft Academic Search

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

E. Atzmon

250

Noncommutative geometry and reality  

Microsoft Academic Search

We introduce the notion of realstructure in our spectral geometry. This notion is motivated by Atiyah’s KR-theory and by Tomita’s involution J. It allows us to remove two unpleasant features of the ‘‘Connes–Lott’’ description of the standard model, namely, the use of bivector potentials and the asymmetry in the Poincare´ duality and in the unimodularity condition.

Alain Connes

1995-01-01

251

Noncommutative Geometry and Reality.  

National Technical Information Service (NTIS)

We introduce the notion of real structure in our spectral geometry. This notion is motivated by Atiyah's KR-theory and by Tomita's involution J. It allows us to remove two unpleasant features of the 'Connes-Lott' description of the standard model, namely ...

A. Connes

1995-01-01

252

Noncommutative Projective Geometry  

Microsoft Academic Search

\\u000a The aim of the three lectures I gave at Constanta was to introduce the audience to the theory of “Noncommutative Pro- jective\\u000a Geometry.” The material for these talks was taken from the survey article (6) and so this abstract will give a very brief discussion of this material leaving the reader to see (6) for the details.

J. T. Stafford

253

Prolog and Geometry Projects  

Microsoft Academic Search

Prolog is a userful tool for geometry and graphics implementations because its primitives, such as unification, match the requiements of many geometric algorithms. During the last two years, we have implemented programs to solve several problems in Prolog, including a subset of the Graphical Kernel System, convex-hull calculation, planar graph traversal, recognition of groupings of objects, Boolean combinations of polygons

W. R. Franklin; P. Y. F. Wu; Sumitro Samaddar; Margaret Nichols

1986-01-01

254

Gravity is Geometry.  

ERIC Educational Resources Information Center

Clarifies two concepts of gravity--those of a fictitious force and those of how space and time may have geometry. Reviews the position of Newton's theory of gravity in the context of special relativity and considers why gravity (as distinct from electromagnetics) lends itself to Einstein's revolutionary interpretation. (JN)

MacKeown, P. K.

1984-01-01

255

Inflation from Quantum Geometry  

Microsoft Academic Search

Quantum geometry predicts that a universe evolves through an inflationary phase at small volume before exiting gracefully into a standard Friedmann phase. This does not require the introduction of additional matter fields with ad hoc potentials; rather, it occurs because of a quantum gravity modification of the kinetic part of ordinary matter Hamiltonians. An application of the same mechanism can

Martin Bojowald

2002-01-01

256

The Geometry of Viruses.  

ERIC Educational Resources Information Center

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

Case, Christine L.

1991-01-01

257

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

258

Geometry of spinor regularization  

NASA Technical Reports Server (NTRS)

The Kustaanheimo theory of spinor regularization is given a new formulation in terms of geometric algebra. The Kustaanheimo-Stiefel matrix and its subsidiary condition are put in a spinor form directly related to the geometry of the orbit in physical space. A physically significant alternative to the KS subsidiary condition is discussed. Derivations are carried out without using coordinates.

Hestenes, D.; Lounesto, P.

1983-01-01

259

Spinorial Geometry and Supergravity  

Microsoft Academic Search

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

JOSEPH J. GILLARD

2006-01-01

260

Topics in Computational Geometry.  

National Technical Information Service (NTIS)

Two problems in computational geometry are solved. The first is to characterize the behavior of the nearest-neighbor search algorithm based on the k-d tree data structure. The k-d tree is a data structure useful in classification and analysis of multidime...

J. E. Zolnowsky

1978-01-01

261

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.

Hsu, K J; Hsu, A J

1990-01-01

262

Secretory pathways generating immunosuppressive NKG2D ligands  

PubMed Central

Natural Killer Group 2 member D (NKG2D) activating receptor, present on the surface of various immune cells, plays an important role in activating the anticancer immune response by their interaction with stress-inducible NKG2D ligands (NKG2DL) on transformed cells. However, cancer cells have developed numerous mechanisms to evade the immune system via the downregulation of NKG2DL from the cell surface, including the release of NKG2DL from the cell surface in a soluble form. Here, we review the mechanisms involved in the production of soluble NKG2DL (sNKG2DL) and the potential therapeutic strategies aiming to block the release of these immunosuppressive ligands. Therapeutically enabling the NKG2D-NKG2DL interaction would promote immunorecognition of malignant cells, thus abrogating disease progression.

Baragano Raneros, Aroa; Suarez-Alvarez, Beatriz; Lopez-Larrea, Carlos

2014-01-01

263

Conformal invariance: From Weyl to SO(2,d)  

NASA Astrophysics Data System (ADS)

The present work deals with two different but subtilely related kinds of conformal mappings: Weyl rescaling in d > 2 dimensional spaces and SO(2,d) transformations. We express how the difference between the two can be compensated by diffeomorphic transformations. This is well known in the framework of string theory but in the particular case of d = 2 spaces. Indeed, the Polyakov formalism describes world sheets in terms of two-dimensional conformal field theory (CFT). On the other hand, Zumino had shown that a classical four-dimensional Weyl-invariant field theory restricted to live in Minkowski space leads to an SO(2,4)-invariant field theory. We extend Zumino's result to relate Weyl and SO(2,d) symmetries in arbitrary conformally flat spaces (CFS). This allows us to assert that a classical SO(2,d)-invariant field does not distinguish, at least locally, between two different d-dimensional CFSs.

Faci, S.

2013-02-01

264

A novel improved method for analysis of 2D diffusion relaxation data—2D 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.

Tønning, Erik; Polders, Daniel; Callaghan, Paul T.; Engelsen, Søren B.

2007-09-01

265

Investigations of flowfields found in typical combustor geometries  

NASA Technical Reports Server (NTRS)

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

Lilley, D. G.

1982-01-01

266

2D director calculation for liquid crystal optical phased array  

NASA Astrophysics Data System (ADS)

A practical numerical model for a liquid crystal cell is set up based on the geometrical structure of liquid crystal optical phased arrays. Model parameters include width and space of electrodes, thickness of liquid crystal layer, alignment layers and glass substrates, pre-tilted angles, dielectric constants, elastic constants and so on. According to electrostatic field theory and Frank-Oseen elastic continuum theory, 2D electric potential distribution and 2D director distribution are calculated by means of the finite difference method on non-uniform grids. The influence of cell sizes on director distribution is analyzed. The fringe field effect between electrodes is also discussed.

Xu, L.; Zhang, J.; Wu, L. Y.

2005-01-01

267

Experimental validation of equations for 2D DIC uncertainty quantification.  

SciTech Connect

Uncertainty quantification (UQ) equations have been derived for predicting matching uncertainty in two-dimensional image correlation a priori. These equations include terms that represent the image noise and image contrast. Researchers at the University of South Carolina have extended previous 1D work to calculate matching errors in 2D. These 2D equations have been coded into a Sandia National Laboratories UQ software package to predict the uncertainty for DIC images. This paper presents those equations and the resulting error surfaces for trial speckle images. Comparison of the UQ results with experimentally subpixel-shifted images is also discussed.

Reu, Phillip L.; Miller, Timothy J.

2010-03-01

268

2-D wavelet packet spectrum for texture analysis.  

PubMed

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

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

2013-06-01

269

Control law decoupling for 2-D biped walking system.  

PubMed

An explicit form of decoupled controls of a 2-D biped walking system is developed for use in simulation studies. The Lagrangian for an n-link 2-D biped system is first set down. The Lagrange formalism is then written as a state-space representation and a block-diagram scheme is proposed. Next, the direct nonlinear decoupling method is introduced, and an explicit form of generating rules is derived. The pole assignment problem is considered. The case of an n-degree of freedom biped system is investigated. PMID:18244074

Cotsaftis, M; Vibet, C

1988-01-01

270

Evaluation of 2D ceramic matrix composites in aeroconvective environments  

NASA Technical Reports Server (NTRS)

An evaluation is conducted of a novel ceramic-matrix composite (CMC) material system for use in the aeroconvective-heating environments encountered by the nose caps and wing leading edges of such aerospace vehicles as the Space Shuttle, during orbit-insertion and reentry from LEO. These CMCs are composed of an SiC matrix that is reinforced with Nicalon, Nextel, or carbon refractory fibers in a 2D architecture. The test program conducted for the 2D CMCs gave attention to their subsurface oxidation.

Riccitiello, Salvatore R.; Love, Wendell L.; Balter-Peterson, Aliza

1992-01-01

271

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

272

CH2D+, the Search for the Holy Grail  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

273

2D:4D and Sexually Dimorphic Facial Characteristics  

Microsoft Academic Search

The second-to-fourth-digit ratio (2D:4D) may be related to prenatal testosterone and estrogen levels and pubertal face growth.\\u000a Several studies have recently provided evidence that 2D:4D is associated with other-rated facial masculinity and dominance,\\u000a but not with facialmetric measures of masculinity. We found that localized face shape differences, shown here to be sexually\\u000a dimorphic and related to ratings of dominance, were

Robert P. Burriss; Anthony C. Little; Emma C. Nelson

2007-01-01

274

Noninvasive deep Raman detection with 2D correlation analysis  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

275

2D full wave modeling for a synthetic Doppler backscattering diagnostic.  

PubMed

Doppler backscattering (DBS) is a plasma diagnostic used in tokamaks and other magnetic confinement devices to measure the fluctuation level of intermediate wavenumber (k(?)?(s) ~ 1) density fluctuations and the lab frame propagation velocity of turbulence. Here, a synthetic DBS diagnostic is described, which has been used for comparisons between measurements in the DIII-D tokamak and predictions from nonlinear gyrokinetic simulations. To estimate the wavenumber range to which a Gaussian beam would be sensitive, a ray tracing code and a 2D finite difference, time domain full wave code are used. Experimental density profiles and magnetic geometry are used along with the experimental antenna and beam characteristics. An example of the effect of the synthetic diagnostic on the output of a nonlinear gyrokinetic simulation is presented. PMID:23126989

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

2012-10-01

276

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

277

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

278

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

279

2D divertor design calculations for the Nataional High-power Advanced Torus Experiment  

SciTech Connect

The National High Power Advanced Torus Experiment is a concept for a new facility to address the FESAC Theme of "Taming the Plasma-Material Interface." This concept exploits the compactness and excellent access provided by low aspect ratio to achieve a high ratio of exhaust power to major radius in order to study the integration of high-performance, long-pulse plasmas with a reactor-relevant high heat flux plasma boundary. Predictions of the scrape-off-layer plasma characteristics are presented, as calculated with the 2D edge modeling code SOLPS. Calculations in a variety of magnetic geometries indicate that very high levels of divertor heat flux can be expected, with peak values far in excess of the power handling capabilities of presently-used materials. Possible methods to reduce the heat flux to acceptable levels are discussed.

Canik, John [ORNL; Maingi, R. [Oak Ridge National Laboratory (ORNL); Owen, Larry W [ORNL; Menard, J. [Princeton Plasma Physics Laboratory (PPPL); Goldston, R. [Princeton Plasma Physics Laboratory (PPPL); Kotschenreuther, M. [University of Texas, Austin; Valanju, P. [University of Texas, Austin; Mahajan, S. [University of Texas, Austin

2009-01-01

280

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

NASA Technical Reports Server (NTRS)

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

Pulliam, T. H.

1994-01-01

281

Geometry of thermodynamic control  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

282

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

283

Puzzle geometry and rigidity  

NASA Astrophysics Data System (ADS)

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

Smania, Daniel

2007-07-01

284

Rényi 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. Rényi entropies are natural generalizations of the entanglement entropy that are much less understood. Above two spacetime dimensions, the universal terms in the Rényi entropies are unknown for general entangling geometries. We conjecture a new structure in the dependence of the four-dimensional Rényi 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 Rényi entropies across cylindrical entangling surfaces to corresponding three-dimensional massive Rényi entropies across circular entangling surfaces. Our numerical technique also allows us to directly probe other interesting aspects of three-dimensional Rényi entropy, including the massless renormalized Rényi entropy and calculable contributions to the perimeter law.

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

2014-06-01

285

Brane Universe: Global Geometry  

SciTech Connect

The global geometries of bulk vacuum space-times in the brane-universe models are investigated and classified in terms of geometrical invariants. The corresponding Carter-Penrose diagrams and embedding diagrams are constructed. It is shown that for a given energy-momentum induced on the brane there can be different types of global geometries depending on the signs of a bulk cosmological term and surface energy density of the brane (the sign of the latter does not influence the internal cosmological evolution). It is shown that in the Randall-Sundrum scenario it is possible to have an asymmetric hierarchy splitting even with a Z{sub 2}-symmetric matching of 'our' brane to the bulk.

Berezin, Victor [Institute for Nuclear Research, Russian Academy of Sciences, 60th October Anniversary Prospect, 7a, 117312, Moscow (Russian Federation)

2010-06-23

286

Noncommutative Geometry Year 2000  

Microsoft Academic Search

\\u000a Our geometric concepts evolved first through the discovery of Non-Euclidean geometry. The discovery of quantum mechanics in\\u000a the form of the noncommuting coordinates on the phase space of atomic systems entails an equally drastic evolution. We describe\\u000a a basic construction which extends the familiar duality between ordinary spaces and commutative algebras to a duality between\\u000a Quotient spaces and Noncommutative algebras.

Alain Connes

2000-01-01

287

Gravity from Noncommutative Geometry  

Microsoft Academic Search

We introduce the linear connection in the noncommutative geometry model of\\u000athe product of continuous manifold and the discrete space of two points. We\\u000adiscuss its metric properties, define the metric connection and calculate the\\u000acurvature. We define also the Ricci tensor and the scalar curvature. We find\\u000athat the latter differs from the standard scalar curvature of the manifold

Andrzej Sitarz

1994-01-01

288

Curved geometry and Graphs  

NASA Astrophysics Data System (ADS)

Quantum Graphity is an approach to quantum gravity based on a background independent formulation of condensed matter systems on graphs. We summarize recent results obtained on the notion of emergent geometry from the point of view of a particle hopping on the graph. We discuss the role of connectivity in emergent Lorentzian perturbations in a curved background and the Bose-Hubbard (BH) model defined on graphs with particular symmetries.

Caravelli, Francesco

2012-05-01

289

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

NASA Astrophysics Data System (ADS)

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.

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

2010-10-01

290

Atomistic simulations of J-integral in 2D graphene nanosystems.  

PubMed

The J-integral is investigated in discrete atomic systems using molecular mechanics simulations. A method of calculating J-integral in specified atomic domains is developed. Two cases, a semiinfinite crack in an infinite domain under the remote K-field deformation and a finite crack length in a finite geometry under the tensile and shear deformation prescribed on the boundary, are studied in the two-dimensional graphene sheets and the values of J-integral are obtained under small-strain deformation. The comparison with energy release rates in Mode I and Mode II based on continuum theory of linear elastic fracture mechanics show good agreements. Meanwhile, the nonlinear strain and stress relation of a 2D graphene sheet is evaluated and is fitted with a power law curve. With necessary modifications on the Tersoff-Brenner potential, the critical values of J-integral of 2D graphene systems, which denoted as Jc, are eventually obtained. The results are then compared with those from the relevant references. PMID:16430147

Jin, Y; Yuan, F G

2005-12-01

291

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

292

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

2008-04-01

293

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

294

A multiple-point statistics algorithm for 3D pore space reconstruction from 2D images  

NASA Astrophysics Data System (ADS)

Fluid flow behavior in a porous medium is a function of the geometry and topology of its pore space. The construction of a three dimensional pore space model of a porous medium is therefore an important first step in characterizing the medium and predicting its flow properties. A stochastic technique for reconstruction of the 3D pore structure of unstructured random porous media from a 2D thin section training image is presented. The proposed technique relies on successive 2D multiple point statistics simulations coupled to a multi-scale conditioning data extraction procedure. The Single Normal Equation Simulation Algorithm (SNESIM), originally developed as a tool for reproduction of long-range, curvilinear features of geological structures, serves as the simulation engine. Various validating criteria such as marginal distributions of pore and grain, directional variograms, multiple-point connectivity curves, single phase effective permeability and two phase relative permeability calculations are used to analyze the results. The method is tested on a sample of Berea sandstone for which a 3D micro-CT scanning image is available. The results confirm that the equi-probable 3D realizations obtained preserve the typical patterns of the pore space that exist in thin sections, reproduce the long-range connectivities, capture the characteristics of anisotropy in both horizontal and vertical directions and have single and two phase flow characteristics consistent with those of the measured 3D micro-CT image.

Hajizadeh, Alireza; Safekordi, Aliakbar; Farhadpour, Farhad A.

2011-10-01

295

Modeling and Control of 2-D Grasping of an Object with Arbitrary Shape under Rolling Contact  

NASA Astrophysics Data System (ADS)

Modeling, control, and stabilization of dynamics of two-dimensional object grasping by using a pair of multi-joint robot fingers are investigated under rolling contact constraints and an arbitrary geometry of the object and fingertips. First, a fundamental testbed problem of modeling and control of rolling motion between 2-D rigid bodies with an arbitrary shape is treated under the assumption that the two contour curves coincide at the contact point and share the same tangent. The rolling constraint induces the Euler equation of motion that is parameterized by a common arclength parameter and constrained onto the kernel space orthogonally complemented to the image space spanned from the constraint gradient. By extending the analysis to the problem of stable grasp of a 2-D object with an arbitrary shape by a pair of robot fingers, the Euler-Lagrange equation of motion of the overall fingers/object system parametrized by arclength parameters is derived, together with a couple of first-order differential equations that express evolutions of contact points in terms of the second fundamental form. It is shown that 2-D rolling constraints are integrable in the sense of Frobonius even if their Pfaffian forms are characterized by arclength parameters. A control signal called “blind grasping” is introduced and shown to be effective in stabilization of grasping without using the details of the object shape and parameters or external sensing. An extension of the Dirichlet-Lagrange stability theorem to a class of systems with DOF-redundancy under constraints is suggested by using a Morse-Bott-Lyapunov function.

Arimoto, Suguru; Yoshida, Morio; Sekimoto, Masahiro; Tahara, Kenji

296

Advanced 2D structures metrology with CD-SEM for OPC challenges  

NASA Astrophysics Data System (ADS)

The rapid shrink of device dimensions requires not only excellent 1D CD precision, but also characterization of corner rounding and line end shape. To meet this on-going trend the industry is in a quest for higher resolution metrology tools, which in-turn drives the use of SEM metrology as more crucial. The industry challenge is to reduce corner rounding and area loss. The metrology challenge, is to be able to measure accurately and precisely these characters, in order to be able to control your process. In our study we will introduce the development of a new algorithm for general shape analysis. The purpose of this algorithm is to allow effective control of the correspondence of the feature"s shape to the design geometry. The disadvantage of the standard CD SEM metric such as contact area was discussed widely in the literature but new metrics were not discussed yet. We consider the following issues and challenges related to the development of a generic algorithm for general shape 2D analysis. First stage of this algorithm is a generic segmentation of the two dimensional features. It should be robust to noise, as well as brightness and contrast changes. Output of this phase will be the contour representing the bottom of the feature. The second stage is the obtaining of new CD metrics for these contours, especially for contours corresponding to contacts with OPC structures. We consider the corner rounding as an example of such new metric. The same techniques can be elaborated for a large range of 2D structures with different levels of complexity. The obtaining of new metrics can be useful as handles for advanced process control (i.e. what to measure on the 2D feature with complex shape such as contact with OPC structures). We consider in this paper the application of the developed metrics for reticle contact with OPC structure monitoring problem that simulates a high level of complexity.

Kris, Roman; Tam, Aviram; Peltinov, Ram; Menadeva, Ovadya; Adan, Ofer; Wertsman, Nadav; Vilenkin, Arcadiy

2005-01-01

297

An interactive 2-D power-line modeling and simulation tool  

NASA Astrophysics Data System (ADS)

The U.S. Army Research Laboratory's Power-Line unmanned aerial vehicle (UAV) Modeling and Simulation (ARL-PLUMS) is a tool for estimating and analyzing quasi-static electric and magnetic fields due to power lines. This tool consists of an interactive 2-D graphical user interface (GUI) and a compute engine that can be used to calculate and visualize the E-Field and H-Field due to as many as seven conductors (two 3-phase circuits and a ground wire). ARL-PLUMS allows the user to set the geometry of the lines and the load conditions on those lines, and then calculate Ey, Ez, Hy, or Hz along a linear path or cutting plane, or in the form of a movie. The path can be along the ground or in the air to simulate the fields that might be observed, for example, by a robotic vehicle or a UAV. ARL-PLUMS makes several simplifying assumptions in order to allow simulations to be completed on a laptop PC interactively. In most cases, the results are excellent, providing a "90% solution" in just a few minutes of total modeling and simulation time. This paper describes the physics used by ARL-PLUMS, including the simplifying assumptions and the 2-D Method of Moments solver. Examples of electric and magnetic fields for different wire configurations, including typical 3-phase distribution and transmissions lines, are provided. Comparisons to similar results using a full 3-D model are also shown, and a discussion of errors that may be expected from the 2-D simulations is provided.

Hull, David; Adelman, Ross

2012-05-01

298

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

299

Tearing Mode Stability in 1D and 2D.  

National Technical Information Service (NTIS)

A stability code for tearing modes in 1D and 2D straight equilibria in the tokamak scaling has been developed. It finds the lowest eigenvalues of a Hermitian problem which is obtained analytically by a reduction of the full problem. The main advantage is ...

W. Kerner H. Tasso

1981-01-01

300

Determination of Saturation Intensity in NH2D.  

National Technical Information Service (NTIS)

Saturated absorption of monochromatic radiation by a Doppler-broadened transition in NH2D has been measured as a function of intensity. The transition was Stark tuned into coincidence with the 10.6 micrometers P(20) line of a CO2 laser. We thereby determi...

L. Thielman L. W. Davis

1974-01-01

301

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

302

Simulating 2D Tearing Phenomena for Interactive Medical Surgery Simulators  

Microsoft Academic Search

This paper introduces a methodology to simulate a particular kind of the fracture phenomenon : the tearing one. The objective of the method is to provide realistic tear- ing simulations, occuring on 2D deformable objects, and working in real-time. This method can find applications in surgery simulators, where te aring human tissue is an important feature to provide. It can

François Boux De Casson; Christian Laugier

2000-01-01

303

Picture Languages: From Wang Tiles to 2D Grammars  

Microsoft Academic Search

The aim of this paper is to collect definitions and results on t he main classes of 2D languages introduced with the attempt of generalizing regular and context-free string languages and in same time preserving some of their nice properties. Almost all the models here described are based on tiles. So we also summarize some results on Wang tiles and

Alessandra Cherubini; Matteo Pradella

2009-01-01

304

Consistent 2-D phase unwrapping guided by a qualtiy map  

Microsoft Academic Search

The problem of 2-D phase unwrapping arises when a spatially varying quantity is measured modulo some period. One needs to reconstruct a smooth unwrapped phase, consistent with the original data, by adding a multiple of the period to each sample. Smoothness typically cannot be enforced over all of the scene, due to noise and localized jumps. An unwrapping algorithm may

1995-01-01

305

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

306

Compensation of packaging asymmetry in a 2-D wind sensor  

Microsoft Academic Search

The influence of packaging on the behaviour of a 2-D thermal wind sensor has been investigated. Non-ideal packaging increases the thermal asymmetry in the sensor, which in turn distorts its output signal. Such distortion can be compensated for by adjusting the heat distribution in the sensor. Using a combination of CAD modeling techniques, expressions have been derived from which the

S. P. Matova; K. A. A. Makinwa; J. H. Huijsing

2002-01-01

307

Design Arbitrary Shaped 2D Acoustic Cloak without Singularity  

Microsoft Academic Search

A method is proposed to design arbitrary shaped two dimensional (2D) isotropic-inertia acoustic cloaks without singularity. The method is based on the deformation view of the transformation method, where the transformation tensor A is identified as the deformation gradient tensor and the transformed material parameters can be expressed by the principal stretches in the principal system of the deformation. The

Jin Hu; Xiaoming Zhou; Gengkai Hu

2009-01-01

308

Consistent 2-D phase unwrapping guided by a quality map  

Microsoft Academic Search

The problem of 2D phase unwrapping arises when a spatially varying quantity is measured module some period. One needs to reconstruct a smooth unwrapped phase, consistent with the original data, by adding a multiple of the period to each sample. Smoothness typically cannot be enforced over all of the scene, due to noise and localized jumps. An unwrapping algorithm may

Thomas J. Flynn

1996-01-01

309

Model based phase unwrapping of 2-D signals  

Microsoft Academic Search

A parametric model and a corresponding parameter estimation algorithm for unwrapping 2-D phase functions are presented. The proposed algorithm performs global analysis of the observed signal. Since this analysis is based on parametric model fitting, the proposed phase unwrapping algorithm has low sensitivity to phase aliasing due to low sampling rates and noise, as well as to local errors. In

Benjamin Friedlander; J. M. Francos

1996-01-01

310

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

311

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

312

2D signature for detection and identification of drugs  

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

313

Protein Folding in 3-d and 2-d  

NSDL National Science Digital Library

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

Brian White (University of Massachusetts;)

2006-06-18

314

Iterative learning control synthesis based on 2-D system theory  

Microsoft Academic Search

An algorithm is presented for iterative learning of the control input for a linear discrete-time multivariable system. Necessary and sufficient conditions are stated for convergence of the proposed algorithm. The algorithm synthesis and analysis are based on two-dimensional (2-D) system theory. A numerical example is given

J. E. Kurek; M. B. Zaremba

1993-01-01

315

The 2D lid-driven cavity problem revisited  

Microsoft Academic Search

Numerical simulations of the 2D lid-driven cavity flow are performed for a wide range of Reynolds numbers. Accurate benchmark results are provided for steady solutions as well as for periodic solutions around the critical Reynolds number. Numerous comparisons with the results available in the literature are given. The first Hopf bifurcation is localized by a study of the linearized problem.

Charles-Henri Bruneau; Mazen Saad

2006-01-01

316

The AAO 2dF QSO Redshift Survey  

Microsoft Academic Search

We describe the aims, strategy and status of the AAO 2dF QSO redshift survey. This goal of the survey is to obtain redshifts for 30000 QSOs in a homogeneous magnitude limited (B<21) survey. The survey began in early 1997 and should be complete by the end of 1999.

Boyle; R. J. Smith; T. Shanks; S. M. Croom; L. Miller

1997-01-01

317

Shear modulus imaging with 2-D transient elastography  

Microsoft Academic Search

In previous work, we have shown that time-resolved 2-D transient elastography is a promising technique for characterizing the elasticity of soft tissues. It involves the measurement of the displacements induced by the propagation of low frequency (LF) pulsed shear waves in biological tissues. In this paper, we present a novel apparatus that contains a LF vibrating device surrounding a linear

Laurent Sandrin; Mickl Tanter; Stefan Catheline; Mathias Fink

2002-01-01

318

Piezoeffect in fluorographane-like 2D supracrystals  

NASA Astrophysics Data System (ADS)

The components of the tensor of piezoelectric constants of fluorographane-like 2D supracrystals have been calculated. It has been shown that their values can be higher than those of lithium niobate. The obtained results can be used in the development of piezotransducers for the excitation and detection of terahertz elastic waves in nanoribbons and nanotubes.

Brazhe, R. A.; Kochaev, A. I.; Sovetkin, A. A.

2013-10-01

319

Hopkinson bar simulation using DYNA2D. Revision 1  

SciTech Connect

A finite-element simulation of a Split Hopkinson's bar (Kolsky apparatus) technique involving mortar specimens is accomplished with DYNA2D, an explicit two-dimensional finite-element code. Calculations are compared with experimental results contained in a University of Florida report Dynamic Response of Concrete and Concrete Structures, and with analytic solutions of the appropriate wave propagation problem.

Smith, J.A.; Glover, T.A.

1985-05-01

320

The toroidal Hausdorff dimension of 2d Euclidean quantum gravity  

NASA Astrophysics Data System (ADS)

The lengths of shortest non-contractible loops are studied numerically in 2d Euclidean quantum gravity on a torus coupled to conformal field theories with central charge less than one. We find that the distribution of these geodesic lengths displays a scaling in agreement with a Hausdorff dimension given by the formula of Y. Watabiki.

Ambjørn, J.; Budd, T.

2013-07-01

321

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

322

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

323

On 2D Motion Parameters for Flapping Wing Propulsion  

Microsoft Academic Search

The paper discusses how to obtain favourable 2D- motion parameters for a apping wing propulsion sys- tem. To nd parameter sets with a high propulsion eciency , two dieren t approaches are considered: A biomimic approach is undertaken, where the motion parameters of a dragony are derived from slow moti- on lm material of a dragony in search igh t

Jan Windte; K.-C. Pngsten

324

Submillimeter-Wave Spectrum of CH2D+  

NASA Astrophysics Data System (ADS)

In interstellar carbon chemistry, CH_3^+ is thought to be an important and abundant molecular ion. However, as it is a symmetric planar molecule and, as a result, it has no permanent dipole moment, it is almost impossible to detect this species by radio astronomical observations. Its deuterated species, CH_2D^+ and CHD_2^+, possess the dipole moment, so the rotational lines should be observable. Rösslein et al. and Jagod et al. observed the infrared spectra of these deuterated species. Demuynck and coworkers tried to observe CH_2D^+ rotational lines in an extended negative glow discharge with no success. More recently Lis et al. reported tentative identification of CH_2D^+ toward Ori IRc2. The molecular constants and the predicted rotational transition frequencies given by Röslein et al. were a good starting point in searching for the rotational lines. A very weak feature was found almost exactly at the calculated frequency for the 212-111 transition. Eventually the line appeared stronger enough for precise frequency measurements, after adjusting the reaction conditions. The optimum gas mixture was found to be CH_4 (˜ 3 mTorr), CD_4 (˜ 1 mTorr), H_2 (˜ 2 mTorr), and He (˜ 35 mTorr). It is interesting to note that helium is essential to produce CH_2D^+. No signals were detectable with Ar buffer.

Amano, T.

2010-06-01

325

Submillimeter-wave spectrum of CH2D+  

NASA Astrophysics Data System (ADS)

Aims: Recently a tentative identification of CH2D+ in interstellar space has been reported. To facilitate astronomical identifications, laboratory measurements of precise rest frequencies for the rotational lines of CH2D+ should be carried out. Methods: A submillimeter-wave spectrometer is used for detection of CH2D+. The CH2D+ ion is generated in an extended negative glow discharge operated at liquid nitrogen temperature. The optimum gas mixture is found to be CH4 (~3 mTorr), CD4 (~1 mTorr), and H2 (~2 mTorr) in helium buffer. Results: Four rotational lines have been detected in the frequency range of 280-890 GHz. The measured frequencies agree very well within a MHz with the predictions given by Rösslein et al. from the infrared spectra. Conclusions: Two rotational lines of this ion have been tentatively identified toward Ori IRc2. The rest frequencies obtained here should facilitate identifications and analysis of astronomical spectra.

Amano, T.

2010-06-01

326

FLIRT - Interest regions for 2D range data  

Microsoft Academic Search

Local image features are used for a wide range of applications in computer vision and range imaging. While there is a great variety of detector-descriptor combinations for image data and 3D point clouds, there is no general method readily available for 2D range data. For this reason, the paper first proposes a set of benchmark experiments on detector repeatability and

Gian Diego Tipaldi; Kai Oliver Arras

2010-01-01

327

Math Forum: K-12 Geometry  

NSDL National Science Digital Library

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

1997-01-01

328

Flood hazard assessment using 1D and 2D approaches  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

329

Articulated registration of 3D human geometry to X-ray image  

Microsoft Academic Search

A fully automatic 3D-2D articulated registration algorithm for aligning a whole-body human geometry to a 2D X-ray image is presented. Domain prior in the form of a hierarchi- cal model encapsulating the kinematic structure of the human body is exploited. A deformation operator is then defined with respect to the hierarchical model. An iterative search using ICP is performed to

Sang N. Le; Jayashree Karlekar; Anthony C. Fang

2008-01-01

330

Resonances of piezoelectric plate with embedded 2D electron system  

NASA Astrophysics Data System (ADS)

A thin GaAs/AlGaAs plate was studied by the resonant ultrasound spectroscopy (RUS) in the temperature range 0.3-10 K and in magnetic fields of up to 18 T. The resonance frequencies and linewidths were measured. Quantum oscillations of both these values were observed and were associated with the quantum Hall effect occurred in the 2D electron system. For an analysis the sample was treated as a dielectric piezoelectric plate covered on one side by a film with a field dependent conductivity. Screening of the strain-driven electric field was changed due to the variation of the electron relaxation time in the vicinity of the metal-dielectric transitions caused by the magnetic field in the 2D system. The dielectric film does not affect properties of GaAs and thus the resonance frequencies are defined only by the elastic, piezoelectric and dielectric constants of GaAs. A metallic 2D sheet effectively screens the parallel electric field, so the ultrasound wave velocities and resonance frequencies decrease when the sheet conductivity increases. Oscillations of the resonance linewidth reflect the influence of the 2D system on the ultrasound attenuation, which is proportional to the linewidth. A metallic film as well as a dielectric one does not affect this attenuation but at some finite nonzero value of the conductivity the linewidth approaches a maximum. In high magnetic field each oscillation of the conductivity produces one oscillation of a resonance frequency and two linewidth peaks. The observed phenomena can be described by the relaxation type equations and the resonant ultrasound spectroscopy opens another opportunity for contactless studies on 2D electron systems.

Suslov, A. V.

2009-02-01

331

Numerical inversion and assessment of 2D Laplace transforms using the Brancik algorithm and its use in 3D holography  

NASA Astrophysics Data System (ADS)

An analytic examination of 3D holography under a 90° recording geometry was carried out earlier in which 2D spatial Laplace transforms were introduced in order to develop transfer functions for the scattered outputs under readout [1,2]. Thereby, the resulting reconstructed output was obtained in the 2D Laplace domain whence the spatial information would be found only by performing a 2D Laplace inversion. Laplace inversion in 2D was attempted by testing a prototype function for which the analytic result was known using two known inversion algorithms, viz., the Brancik and the Abate [2]. The results indicated notable differences in the 3D plots between the algorithms and the analytic result, and hence were somewhat inconclusive. In this paper, we take a closer look at the Brancik algorithm in order to understand better the implications of the choices of key parameters such as the real and imaginary parts of the Bromwich contour and the grid sizes of the summation operations. To assess the inversion findings, three prototype test cases are considered for which the analytic solutions are known. For specific choices of the algorithm parameters, optimal values are determined that minimize errors in general. It is found that even though errors accumulate near the edges of the grid, overall reasonably accurate inversions are possible to obtain with optimal parameter choices that are verifiable via cross-sectional views. Further work is ongoing whereby the optimized algorithm is to be applied to the 3D holography problem.

Chatterjee, Monish R.; Feng, Le

2014-02-01

332

A 2D block-structured mesh partitioner for accurate flow simulations on non-rectangular geometries  

Microsoft Academic Search

The motivation of this work is to carry out parallel simulations of incompressible flows on block-structured meshes. A new partitioning method is proposed. The quality of rectangular partitions is checked and compared with other methods, as regards load balance, edge-cut and block numbers. The partitioner is coupled with the massively parallel Hypre solver library and efficiency of the coupling is

E. Ahusborde; S. Glockner

2011-01-01

333

Experimental results for film cooling in 2-D supersonic flow including coolant delivery pressure, geometry, and incident shock effects  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

334

COMPARISON OF THE ACCURACY OF VARIOUS SPATIAL DISCRETIZATION SCHEMES OF THE DISCRETE ORDINATES EQUATIONS IN 2D CARTESIAN GEOMETRY  

SciTech Connect

We present a comprehensive error estimation of four spatial discretization schemes of the two-dimensional Discrete Ordinates (SN) equations on Cartesian grids utilizing a Method of Manufactured Solution (MMS) benchmark suite based on variants of Larsen’s benchmark featuring different orders of smoothness of the underlying exact solution. The considered spatial discretization schemes include the arbitrarily high order transport methods of the nodal (AHOTN) and characteristic (AHOTC) types, the discontinuous Galerkin Finite Element method (DGFEM) and the recently proposed higher order diamond difference method (HODD) of spatial expansion orders 0 through 3. While AHOTN and AHOTC rely on approximate analytical solutions of the transport equation within a mesh cell, DGFEM and HODD utilize a polynomial expansion to mimick the angular flux profile across each mesh cell. Intuitively, due to the higher degree of analyticity, we expect AHOTN and AHOTC to feature superior accuracy compared with DGFEM and HODD, but at the price of potentially longer grind times and numerical instabilities. The latter disadvantages can result from the presence of exponential terms evaluated at the cell optical thickness that arise from the semianalytical solution process. This work quantifies the order of accuracy and the magnitude of the error of all four discretization methods for different optical thicknesses, scattering ratios and degrees of smoothness of the underlying exact solutions in order to verify or contradict the aforementioned intuitive expectation.

Sebastian Schunert; Yousry Y. Azmy; Damien Fournier

2011-05-01

335

Flexible Camera Setup for Visual Based Registration on 2D Interaction Surface with Undefined Geometry Using Neural Network  

Microsoft Academic Search

Camera setup, calibration and visual based registration of Augmented Reality (AR) based tabletop setups can be a really complicated and time-intensive task. Homography is often used liberally despite its assumption for planar surfaces, where the mapping from the camera to the table can be expressed by a simple projective homography. However, this approach often fails in curved and non-planar surface

Ary Setijadi Prihatmanto; Michael Haller; Roland Wagner

2006-01-01

336

The Common Geometry Module (CGM): A Generic, Extensible Geometry Interface  

Microsoft Academic Search

Geometry modeling has in the past five years emerge d as a commodity capability; several geometry model ing engines are available which provide largely the same capability , and most high-end CAD systems provide access to their geometry through APIs. However, subtle differences still exist betw een these modelers, both at the syntax level and in the underlying topological models.

Timothy J. Tautges; TIMOTHY J

2000-01-01

337

Computation of neutron fluxes in clusters of fuel pins arranged in hexagonal assemblies (2D and 3D)  

SciTech Connect

For computations of fluxes, we have used Carvik's method of collision probabilities. This method requires tracking algorithms. An algorithm to compute tracks (in 2D and 3D) has been developed for seven hexagonal geometries with cluster of fuel pins. This has been implemented in the NXT module of the code DRAGON. The flux distribution in cluster of pins has been computed by using this code. For testing the results, they are compared when possible with the EXCELT module of the code DRAGON. Tracks are plotted in the NXT module by using MATLAB, these plots are also presented here. Results are presented with increasing number of lines to show the convergence of these results. We have numerically computed volumes, surface areas and the percentage errors in these computations. These results show that 2D results converge faster than 3D results. The accuracy on the computation of fluxes up to second decimal is achieved with fewer lines. (authors)

Prabha, H.; Marleau, G. [Institut de Genie Nucleaire, Ecole Polytechnique de Montreal, Stn. CV, P.O. Box 6079, Montreal, QC H3C 3A7 (Canada)

2012-07-01

338

Preparation and study of 2-D semiconductors with Dirac type bands due to the honeycomb nanogeometry  

NASA Astrophysics Data System (ADS)

The interest in 2-dimensional systems with a honeycomb lattice and related Dirac-­type electronic bands has exceeded the prototype graphene1. Currently, 2-­dimensional atomic2,3 and nanoscale4-­8 systems are extensively investigated in the search for materials with novel electronic properties that can be tailored by geometry. The immediate question that arises is how to fabricate 2D semiconductors that have a honeycomb nanogeometry, and as a consequence of that, display a Dirac-­type band structure? Here, we show that atomically coherent honeycomb superlattices of rocksalt (PbSe, PbTe) and zincblende (CdSe, CdTe) semiconductors can be obtained by nanocrystal self-­assembly and facet-­to-­facet atomic bonding, and subsequent cation exchange. We present a extended structural analysis of atomically coherent 2D honeycomb structures that were recently obtained with self-assembly and facet-­to-­facet bonding9. We show that this process may in principle lead to three different types of honeycomb structures, one with a graphene type-­, and two others with a silicene-­type structure. Using TEM, electron diffraction, STM and GISAXS it is convincingly shown that the structures are from the silicene-­type. In the second part of this work, we describe the electronic structure of graphene-­type and silicene type honeycomb semiconductors. We present the results of advanced electronic structure calculations using the sp3d5s* atomistic tight-­binding method10. For simplicity, we focus on semiconductors with a simple and single conduction band for the native bulk semiconductor. When the 3-­D geometry is changed into 2D honeycomb, a conduction band structure transformation to two types of Dirac cones, one for S-­ and one for P-­orbitals, is observed. The width of the bands depends on the honeycomb period and the coupling between the nanocrystals. Furthermore, there is a dispersionless P-­orbital band, which also forms a landmark of the honeycomb structure. The effects of considerable intrinsic spin-­orbit coupling are briefly considered. For heavy-­element compounds such as CdTe, strong intrinsic spin-­-orbit coupling opens a non-­trivial gap at the P-­orbital Dirac point, leading to a quantum Spin Hall effect10-­12. Our work shows that well known semiconductor crystals, known for centuries, can lead to systems with entirely new electronic properties, by the simple action of nanogeometry. It can be foreseen that such structures will play a key role in future opto-­electronic applications, provided that they can be fabricated in a straightforward way.

Kalesaki, E.; Boneschanscher, M. P.; Geuchies, J. J.; Delerue, C.; Morais Smith, C.; Evers, W. H.; Allan, G.; Altantzis, T.; Bals, S.; Vanmaekelbergh, D.

2014-03-01

339

Infrared pushbroom camera breadboard using off-the-shelf 2D array of detector  

NASA Astrophysics Data System (ADS)

Performances for nowadays optronic systems require focal plane arrays (FPA) with an increasing number of detectors. The `push- broom' technic is well adapted to earth observation in the visible range with the availability of long linear CCD'S offering thousands of pixels. In the infrared, line scan systems are preferred at the present time because technological difficulties have to be overcome in order to get long linear arrays. Among the most important, are: (1) Difficulties to have a large cold focal plane with a temperature uniformity of a few degrees. (2) Difficulties to get good detection material over large surface. Mechanical or optical butting technology can be used there but with dead pixels and/or side effects. (3) Very low cold shield efficiency due to the geometry of the long linear array. (4) Very high development costs. MATRA DEFENSE UAO has made the design of a new infrared FPA concept which has the advantage to overcome all drawbacks listed previously (patented design). The idea consists to transform the pixel arrangement geometry of a 2D array which is available off the shelf into a long linear FPA using a coherent infrared fiber optic reformatter. In order to demonstrate the feasibility of this new FPA concept, a camera breadboard has been built. This task has been supported by the French MOD (STTE). This paper describes this breadboard and gives main technical performances.

Bernier, Joel; Plainchamp, Patrick; Bardon, Dominique

1994-09-01

340

Complex 2D matrix model and geometrical map on the complex-Nc plane  

NASA Astrophysics Data System (ADS)

We study the parameter dependence of the internal structure of resonance states by formulating a complex two-dimensional (2D) matrix model, where the two dimensions represent two levels of resonances. We calculate a critical value of the parameter at which a "nature transition" with character exchange occurs between two resonance states, from the viewpoint of geometry on complex-parameter space. Such a critical value is useful for identifying the internal structure of resonance states with variation of the parameter in the system. We apply the model to analyze the internal structure of hadrons with variation of the color number N_c from infty to a realistic value 3. By regarding 1/N_c as the variable parameter in our model, we calculate a critical color number of the nature transition between hadronic states in terms of a quark-antiquark pair and a mesonic molecule as exotics from the geometry on the complex-N_c plane. For large-N_c effective theory, we employ the chiral Lagrangian induced by holographic QCD with a D4/D8/overline {D8} multi-D brane system in type IIA superstring theory.

Nawa, Kanabu; Ozaki, Sho; Nagahiro, Hideko; Jido, Daisuke; Hosaka, Atsushi

2013-08-01

341

The 2dF Galaxy Redshift Survey 100k Data Release (2dFGRS Team, 2001)  

NASA Astrophysics Data System (ADS)

The 2dF Galaxy Redshift Survey (2dFGRS) is designed to measure redshifts for approximately 250000 galaxies. The 2dFGRS uses the 2dF multifibre spectrograph on the Anglo-Australian Telescope, which is capable of observing 400 objects simultaneously over a 2 degree diameter field. The source catalogue for the survey is a revised and extended version of the APM galaxy catalogue, and the targets are galaxies with extinction-corrected magnitudes brighter than bJ=19.45. The main survey regions are two declination strips, one in the southern Galactic hemisphere spanning 80x15degrees around the South Galactic Pole, and the other in the Northern Galactic hemisphere spanning 75x10degrees along the celestial equator; in addition, there are 99 fields spread over the southern Galactic cap. The survey covers 2000 square degrees and has a median depth of z=0.11. Adaptive tiling is used to give a highly uniform sampling rate of 93% over the whole survey region. The 100k release contains the 102426 objects observed up to 31 January 2001. Redshifts are measured from spectra covering 3600-8000 Angstroms at a two-pixel resolution of 9.0 Angstrom and a median S/N of 13 per pixel. All redshift identifications are visually checked and assigned a quality parameter Q in the range 1-5; Q>=3 redshifts are 98.4% reliable and have an rms uncertainty of 85 km/s. The overall redshift completeness for Q>=3 redshifts is 91.8% but this varies with magnitude from 99% for the brightest galaxies to 90% for objects at the survey limit. The 2dFGRS data base is available on the World Wide Web at http://www.mso.anu.edu.au/2dFGRS. This catalog was extracted from the 2dF Galaxy Redshift Survey 100k release CD-ROMs using the included mSQL database. This catalog comprises the basic spectroscopic information from the best spectrum of each object, that is contained in the extnum=0 rows of the mSQL database. (1 data file).

Colless, M.; Dalton, G.; Maddox, S.; Sutherland, W.; Norberg, P.; Cole, S.; Bland-Hawthorn, J.; Bridges, T.; Cannon, R.; Collins, C.; Couch, W.; Cross, N.; Deeley, K.; de Propris, R.; Driver, S. P.; Efstathiou, G.; Ellis, R. S.; Frenk, C. S.; Glazebrook, K.; Jackson, C.; Lahav, O.; Lewis, I.; Lumsden, S.; Madgwick, D.; Peacock, J. A.; Peterson, B. A.; Price, I.; Seaborne, M.; Taylor, K.

2003-06-01

342

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

343

2-D linear motion system. Innovative technology summary report  

SciTech Connect

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

NONE

1998-11-01

344

Topologiacl Models of 2D Fractal Cellular Structures  

NASA Astrophysics Data System (ADS)

In space-filling 2D cellular structures with trivalent vertices and in which each cell is constrained to share at most one side with any cell and no side with itself, the maximum fraction of three-sided cells is produced by a decoration of vertices of any initial structure by three-sided cells. Fractal cellular structures are obtained if the latter decoration process is iterated indefinitely. Other methods of constructions of fractal structures are also described. The probability distribution P(n) of the number n of cell sides and some two-cell topological properties of a 2D fractal cellular structure constructed from the triangular Sierpinski gasket are investigated. On the whole, the repartition of cells in 2D structures with n geq 3 and P(3) ne 0 evolve regularly when topological disorder, conveniently measured by the variance ?2 of P(n), increases. The strong correlations which exist among cells, in particular in natural structures (?2lesssim 5), decrease progressively when ?2 increases, a cell repartition close to a random one being reached for ?2sim 12. We argue that the structures finally evolve to fractal structures (for which ?2 is infinite) but we have not characterized the latter transition. Dans des structures cellulaires 2D à sommets trivalents qui remplissent l'espace et dans lesquelles une cellule partage au plus un côté avec toute autre cellule et aucun avec elle-même, la proportion maximum admissible de cellules à trois côtés est obtenue par une décoration de tous les sommets d'une structure initiale quelconque par des cellules à trois côtés. Des structures cellulaires “fractales” 2D sont ainsi engendrées si le processus précédent est répété à l'infini. D'autres méthodes de constructions de structures fractales sont également décrites. La distribution de probabilité P(n) du nombre n de côtés des cellules ainsi que des corrélations de paires sont étudiées pour une structure cellulaire fractale construite à partir du tamis de Sierpinski. Au total, la répartition des cellules dans les structures cellulaires 2D avec n geq 3 et P(3) ne 0 évolue de manière régulière lorseque le désordre topologique, commodément représenté par la variance ?2 de P(n), s'accroît. Les fortes corrélations qui existent entre les cellules, en particulier dans les structures naturelles (?2lesssim 5) diminuent progressivement quand ?2 augmente, la répartition des cellules étant proche d'une répartition aléatoire pour ?2sim 12. Enfin les structures évolueraient vers des structures fractales, pour lesquelles ?2 est infini, mais cette dernière transition reste encore à caractériser.

Le Caër, G.; Delannay, R.

1995-11-01

345

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

NASA Astrophysics Data System (ADS)

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

Lian, Yaogang

346

Geometry: Grades 10-12.  

ERIC Educational Resources Information Center

Behavioral objectives, each accompanied by six sample test items, for secondary school geometry are presented. Objectives were determined by surveying the most widely used secondary school geometry textbooks, and cover 14 major categories of geometry, with sections on set theory and introductory trigonometry. Answers are provided. Categories…

Instructional Objectives Exchange, Los Angeles, CA.

347

Computer-Aided Geometry Modeling  

NASA Technical Reports Server (NTRS)

Techniques in computer-aided geometry modeling and their application are addressed. Mathematical modeling, solid geometry models, management of geometric data, development of geometry standards, and interactive and graphic procedures are discussed. The applications include aeronautical and aerospace structures design, fluid flow modeling, and gas turbine design.

Shoosmith, J. N. (compiler); Fulton, R. E. (compiler)

1984-01-01

348

Improving the performance of 2D Discrete Wavelet Transform using data-level parallelism  

Microsoft Academic Search

The JPEG2000 standard uses the 2D Discrete Wavelet Transform (2D DWT), while the JPEG standard uses the 2D Discrete Cosine Transform (DCT). However, the 2D DWT has higher computational requirements than the 2D DCT and consumes a significant part of the total JPEG2000 encoding time. One way to improve the performance of the 2D DWT is using parallel techniques on

Asadollah Shahbahrami

2011-01-01

349

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

350

Unique CYP2D6 activity distribution and genotype-phenotype discordance in black Americans  

Microsoft Academic Search

Background: Although CYP2D6 has been studied extensively in differentpopulation groups, relatively little is known for black Americans.Methods: CYP2D6 activity was assessed with dextromethorphan in 283 black American subjects and correlated with their genotype (2D6*2 to *12, 2D6*14, 2D6*15, 2D6*17, 2D6*18, and 2D6*29 and gene duplications). Volunteers provided information about ethnicity and concurrent medication, and they participated in either phenotyping (n

Andrea Gaedigk; L. DiAnne Bradford; Kenda A. Marcucci; J. Steven Leeder

2002-01-01

351

Transport Equations Resolution By N-BEE Anti-Dissipative Scheme In 2D Model Of Low Pressure Glow Discharge  

NASA Astrophysics Data System (ADS)

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

Kraloua, B.; Hennad, A.

2008-09-01

352

2D Bipyrimidine silver(I) nitrate: Synthesis, X-ray structure, solution chemistry and anti-microbial activity  

Microsoft Academic Search

Synthesis and X-ray single crystal structure analysis of the compound {[Ag2(?2-bpym)(?-O-NO3)2]}n, (1), (where bpym=2,2?-bipyrimidine) are presented. Compound (1) has a (6,3)-2D honeycomb structure with a tetrahedral coordination geometry around the Ag(I) ion. In contrary to the solid state structural investigation, ESI-MS for (1) in solution shows a strong peak at m\\/z 423.0269 which indicates that the [Ag(bpym)2]+ cation is dominating

Alshima'a A. Massoud; Vratislav Langer; Yousry M. Gohar; Morsy A. M. Abu-Youssef; Janne Jänis; Lars Öhrström

2011-01-01

353

Transport Equations Resolution By N-BEE Anti-Dissipative Scheme In 2D Model Of Low Pressure Glow Discharge  

SciTech Connect

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

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

2008-09-23

354

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

355

FPCAS2D user's guide, version 1.0  

NASA Astrophysics Data System (ADS)

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

Bakhle, Milind A.

1994-12-01

356

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

357

Transition to chaos in an open unforced 2D flow  

NASA Technical Reports Server (NTRS)

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

Pulliam, Thomas H.; Vastano, John A.

1993-01-01

358

Micro-structural Fluctuations in 2D Dusty Plasma Liquids  

SciTech Connect

We address structural fluctuations in a cold 2D dusty plasma liquid which is self-organized through the strong Coulomb coupling of the negatively charged micro-meter sized dust particles suspending in weakly ionized discharges. The 2D liquids consist of triangular type ordered domains surrounded by defect clusters, which can be reorganized through avalanche type hopping under the interplay of strong Coulomb coupling and thermal fluctuations. The spatio-temporal evolutions of the local bond-orientational order are directly tracked through digital optical microscopy. The power law scaling of the temporal persistence length of fluctuations is obtained for the cold liquid. The measurement of the conditional probability of the persistence lengths of the successive fluctuating cycles suggests certain types of the persistence length combinations are more preferred. The memory of persistence lasts a few fluctuating cycles.

I Lin; Huang, Y.-H.; Teng, L.-W. [Department of Physics, National Central University, Jhong-Li, Taiwan, 32001 (China)

2007-07-13

359

Track monitoring with single and multiple 2D passive sensors  

NASA Astrophysics Data System (ADS)

In a multiple target environment, hit-to-track data association is important for properly tracking targets in view. Track monitoring is a fast method of determining whether the proper data association has been made. This paper presents track monitoring algorithms for both single and multiple passive 2-D sensors along with analytical methods of evaluating their effectiveness. Single sensor track monitoring produces a dilemma: a poor track is a result of target maneuver or incorrect hit-to-track data association. The algorithm presented for multiple 2-D passive sensors solves the problem by adding inclination angle monitoring. The multiple sensor monitoring system can distinguish between target maneuver, incorrect hit-to-track data association, and the addition problem with multiple sensors of incorrect track-to-track association, or `ghost' tracks. These monitoring methods can be used to prune poor hypotheses in MHT filters or in single assignment tracking when processor power is limited.

Roecker, James A.

1992-08-01

360

Metastability and nucleation in the 2D-Potts ferromagnet  

NASA Astrophysics Data System (ADS)

The nature of the temperature-driven transition of the 2D q>4-Potts model, and the associated metastability, are studied. The problem was firstly investigated by Binder [1,2] in 1981, who discussed the existence of metastable states in a temperature interval below the critical point, which is first-order for q>4. Starting from the droplet expansion theory for the 2D Potts condensation point (Meunier & Morel, 2000 [3]), we compare the metastability derived from the theory with the dynamic metastability found with a local updating rule dynamics. The results are interpreted in terms of the microscopic mechanisms of nucleation, and compared to those described by Classical Nucleation Theory for the Ising model in an external field, which result to be different in several aspects.

de Berganza, Miguel Ibáñez

2009-01-01

361

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

362

Numerical diffraction synthesis of 2-D quasioptical power splitter  

Microsoft Academic Search

A new diffraction synthesis method is proposed for computing quasioptical 2-D reflector beam splitters in the E-polarization case. It is a combination of a numerical gradient (NG) optimization and an efficient analysis method based on singular integral equations (SIEs) which are discretized using a fast and accurate numerical Nystrom-type method of discrete singularities (MDS). The results of design are shown

Andrey A. Nosich; Yuriy V. Gandel; Thore Magath; Ayhan Altintas

2007-01-01

363

Easily Computable Optimum Grasps in 2-D and 3-D  

Microsoft Academic Search

We consider the problem of finding optimum forceclosure grasps of two and three-dimensional objects.Our focus is on grasps which are useful in practice,namely grasps with a small number of fingers, withfriction at the contacts. Assuming frictional contactand rounded finger tips---very mild assumptions inpractice---we give new upper (and lower) bounds onthe number of fingers necessary to achieve force closuregrasps of 2-D

Brian Mirtich; John F. Canny

1994-01-01

364

PISCES-MC: a multiwindow, multimethod 2-D device simulator  

Microsoft Academic Search

A multiwindow, multimethod device analysis algorithm that combines the advantages of efficient drift-diffusion simulators and accurate physical models using Monte Carlo methods is described. The PISCES 2-D device analysis program is used whenever the drift-diffusion model is valid. In situations where the drift-diffusion model breaks down, a window is opened in the part of the device where the hot-carrier effects

D. Y. Cheng; Chang G. Hwang; Robert W. Dutton

1988-01-01

365

Transition in a 2-D lid-driven cavity flow  

Microsoft Academic Search

Direct numerical simulations about the transition process from laminar to chaotic flow in square lid-driven cavity flows are considered in this paper. The chaotic flow regime is reached after a sequence of successive supercritical Hopf bifurcations to periodic, quasi-periodic, inverse period-doubling, period-doubling, and chaotic self-sustained flow regimes. The numerical experiments are conducted by solving the 2-D incompressible Navier–Stokes equations with

Yih-Ferng Peng; Yuo-Hsien Shiau; Robert R. Hwang

2003-01-01

366

Reconstruction of Complex Buildings using LIDAR and 2D Maps  

Microsoft Academic Search

The extraction of the building models from remote-sensed data is an important work in the geographic information systems. This investigation describes an approach to integrate LIDAR data and 2D building boundaries for building reconstruction. The proposed scheme comprises of three major parts: (1) data pre-processing, (2) extraction of building primitive, and (3) shaping. In the data pre-processing, the LIDAR point

Tee-ann Teo; Jiann-Yeou Raul; Liang-chien Chen; Jin-king Liu; Wei-chen Hsu

2006-01-01

367

The partition function of 2d string theory  

Microsoft Academic Search

We derive a compact and explicit expression for the generating functional of\\u000aall correlation functions of tachyon operators in 2D string theory. This\\u000aexpression makes manifest relations of the $c=1$ system to KP flow and\\u000a$W_{1+\\\\infty}$ constraints. Moreover we derive a Kontsevich-Penner integral\\u000arepresentation of this generating functional.

Robbert Dijkgraaf; Gregory Moore; Ronen Plesser

1992-01-01

368

Intensity based 2D-3D registration of cerebral angiograms  

Microsoft Academic Search

We propose a new method for aligning three-di- mensional (3-D) magnetic resonance angiography (MRA) with 2-D X-ray digital subtraction angiograms (DSA). Our method is developed from our algorithm to register computed tomography volumes to X-ray images based on intensity matching of digitally reconstructed radiographs (DRRs). To make the DSA and DRR more similar, we transform the MRA images to images

John H. Hipwell; Graeme P. Penney; Robert A. Mclaughlin; Kawal S. Rhode; Paul E. Summers; Tim C. S. Cox; James V. Byrne; J. Alison Noble; David J. Hawkes

2003-01-01

369

CMOS planar 2D micro-fluxgate sensor  

Microsoft Academic Search

An electronic compass made of a new planar 2D micro-fluxgate sensor is presented. The magnetometer is integrated in a standard CMOS process, and uses a post-processed cross-shaped ferromagnetic amorphous core. This core is diagonally placed above a single square excitation coil common to both measurement axes. The silicon chip includes the driving and readout electronics, the excitation and pick-up coils

L. Chiesi; P. Kejik; B. Janossy; R. S. Popovic

2000-01-01

370

2-D phase unwrapping and instantaneous frequency estimation  

Microsoft Academic Search

The phase of complex signals is wrapped since it can only be measured modulo-2?; unwrapping searches for the 2?-combinations that minimize the discontinuity of the unwrapped phase, as only the unwrapped phase can be analyzed and interpreted by further processing. Given an estimate of the phase gradient (i.e., of the instantaneous frequency), the 2-D unwrapped phase can be obtained as

Umberto Spagnolini

1995-01-01

371

Adaptive Multicast Wormhole Routing in 2D Mesh Multicomputers  

Microsoft Academic Search

. We study the issues of adaptive multicast wormhole routingin 2D mesh multicomputers. Three adaptive multicast wormhole routingstrategies are proposed and studied, which include minimal partial adaptive,minimal fully adaptive and nonminimal multicast routing methods.All the algorithms are shown to be deadlock-free. These are the firstdeadlock-free adaptive multicast wormhole routing algorithms ever proposed.A simulation study has been conducted that compares the

Xiaola Lin; Philip K. Mckinley; Abdol-hossein Esfahanian

1993-01-01

372

2-D Magnetic Recording: Read Channel Modeling and Detection  

Microsoft Academic Search

Two-dimensional magnetic recording (TDMR) is a novel storage architecture that, in theory, can achieve a density of up to 10 Tb\\/in2. It uniquely differs from other proposed next-generation architectures because of its reliance on sophisticated 2-D signal-processing algorithms. Recently, a number of contributions have been made in the development of read-channel models and detectors for TDMR systems. In this paper,

Anantha Raman Krishnan; Rathnakumar Radhakrishnan; Bane Vasic; Aleksander Kavcic; William Ryan; Fatih Erden

2009-01-01

373

Collapse of Cycloidal flow in 2d Crossed Field Gaps  

Microsoft Academic Search

The start up of crossed-field amplifiers and magnetrons can result in noise detrimental to many applications. The transient of a 2d crossed field diode can be divided into three separate stages: cycloidal flow, collapse of cycloidal flow and non-uniform (E×B) sheared flow. Recent 1d results show cycloidal flows will collapse into near Brillouin flow(P. J. Christenson, et. al. Phys. Plasmas),

K. L. Cartwright; P. J. Christenson; J. P. Verboncoeur; C. K. Birdsall

1998-01-01

374

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?.

Remorino, Amanda; Hochstrasser, Robin M.

2012-01-01

375

Novel method for fabrication of volume 2D photonic crystals  

NASA Astrophysics Data System (ADS)

Photonic crystals are wavelength-scale periodic structures built from dielectrics with different refractive indexes As standard 2D photonic crystals are fabricated by lithographic methods, but in this case only planar structure can be obtained. We have adapted stack and draw technique that is usually used for photonic crystal fiber fabrication to develop volume 2D photonic crystals. Technology allows fabrication of high contrast structures with air holes as well as low contrast solid-all structures where air holes are replaced with glass micro rods of refractive index. Use of soft glasses with a high difference in refractive index allows development of a structure where partial photonic band gap exists. The proposed method offers possibility of fabrication volume 2D photonic crystal with a diameter in the order of 1 mm and height of a few mm. Large area photonic crystals are very attractive as new optical material named 'photonic glass' with built-in photonic bandgap functionality. Preliminary fabrication test were performed for two pairs of soft glasses NC21/F2 and SK222/Zr3. The considered glasses are thermally matched and are synthesized in-house except of F2 glass (standard Schott glass). Obtained structures are regular with some defects on the borders between intermediate performs. Some glass diffusion is observed between Zr3 and SK222 glasses. With this technique a 2D photonic crystal with a hexagonal lattice was fabricated with a pair of soft glasses SK222 and Zr3. Microrod diameter is 749nm and lattice constant 1110 nm. Photonic crystal consists of 166421 elements (425 elements on diagonal) and its total surface is about field ~0,178mm2.

Buczynski, Ryszard; Kujawa, Ireneusz; Filipkowski, Adam; Pysz, Dariusz; Hudelist, Florian; Waddie, Andrew; Stepien, Ryszard; Taghizadeh, Mo

2008-05-01

376

QSAR using 2D descriptors and TRIPOS' SIMCA  

Microsoft Academic Search

The combination of 2-dimensional descriptors and classification analysis has seen limited use within drug design either due to the general nature of the descriptors used or by the drive to use only 3D information. We present the use of SIMCA as implemented by TRIPOS in conjunction with our in-house 2D topological descriptors as a means of giving chemically significant analyses

Peter A. Hunt

1999-01-01

377

Cryogenic cavitating flow in 2D laval nozzle  

Microsoft Academic Search

Cavitation is one of the troublesome problems in rocket turbo pumps, and since most of high-efficiency rocket propellants\\u000a are cryogenic fluids, so called “thermodynamic effect” becomes more evident than in water. In the present study, numerical\\u000a and experimental study of liquid nitrogen cavitation in 2D Laval nozzle was carried out, so that the influence of thermodynamic\\u000a effect was examined. It

Naoki Tani; Toshio Nagashima

2003-01-01

378

Highly integrated 2-D capacitive micromachined ultrasonic transducers  

Microsoft Academic Search

Two dimensional (2-D) silicon based capacitive micromachined ultrasonic transducer (cMUT) arrays are fabricated efficiently using standard integrated circuit (IC) processing techniques. Furthermore, high density interconnects are implemented using through-chip vias which bring the signal from the front surface of the transducer chip to the back side. The transducer chip then can be flip-chip bonded to a signal processing chip. This

S. Calmes; C. H. Cheng; F. L. Degertekin; X. C. Jin; S. Ergun; B. T. Khuri-Yakub

1999-01-01

379

Numerical simulation of 2D and 3D compressible flows  

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

380

Propagation of guided elastic waves in 2D phononic crystals.  

PubMed

The phononic band structure of two-dimensional phononic guides is numerically studied. A plane wave expansion method is used to calculate the dispersion relations of guided elastic waves in these periodic media, including 2D phononic plates and thin layered periodic arrangements. We show that, for any guided elastic wave, Lamb or generalised Lamb modes, stop bands appear in the dispersion curves, displaying a phononic band structure in both cases. PMID:16797667

Charles, C; Bonello, B; Ganot, F

2006-12-22

381

Hyperfine Structure in the Microwave Spectrum of NH2D  

Microsoft Academic Search

Hyperfine structure in the 313?303 rotation—inversion transition of deuterated ammonia NH2D at 18 807.7 Mc\\/sec has been studied with a beam maser microwave spectrometer giving a linewidth of 7 kc\\/sec. All details of the observed hyperfine structure have been accounted for in terms of the various quadrupole, spin—rotation, and spin—spin interactions of the four coupling nuclei. The hyperfine coupling constants

P. Thaddeus; L. C. Krisher; P. Cahill

1964-01-01

382

Retrospective analysis of 2D patient-specific IMRT verifications  

Microsoft Academic Search

We performed 858 two-dimensional (2D) patient-specific intensity modulated radiotherapy verifications over a period of 18 months. Multifield, composite treatment plans were measured in phantom using calibrated Kodak EDR2 film and compared with the calculated dose extracted from two treatment planning systems. This research summarizes our findings using the normalized agreement test (NAT) index and the percent of pixels failing the

Nathan L. Childress; R. Allen White; Charles Bloch; Mohammad Salehpour; Lei Dong; Isaac I. Rosen

2005-01-01

383

2D velocity fields of simulated interacting disc galaxies  

Microsoft Academic Search

We investigate distortions in the velocity fields of disc galaxies and their use in revealing the dynamical state of interacting galaxies at different redshifts. We model disc galaxies in combined N-body\\/hydrodynamic simulations. 2D velocity fields of the gas are extracted, which we place at different redshifts from z=0 to z=1 to investigate resolution effects on the properties of the velocity

T. Kronberger; W. Kapferer; S. Schindler; B. L. Ziegler

2007-01-01

384

Quantum Motion on 2D Surface of Nonspherical Topology  

Microsoft Academic Search

An excess term exists when using hermitian form of Cartesian momentum pi (i = 1, 2, 3) in usual kinetic energy 1\\/(2µ) S pi2 for a particle moving on the 2D surface, and the correct kinetic energy turns to be 1\\/(2µ) S 1\\/fipi fi pi where the fi are dummy factors in classical mechanics and nontrivial in quantum mechanics. In

Q. H. Liu; J. X. Hou; Y. P. Xiao; L. X. Li

2004-01-01

385

Differentiation of C2D Macrophage Cells after Adoptive Transfer  

Microsoft Academic Search

Received 8 August 2007\\/Returned for modification 7 October 2007\\/Accepted 5 December 2007 C2D macrophage cells protect immunocompromised mice from experimentally induced pneumonias after intraperitoneal (i.p.) adoptive transfer. These macrophage cells are immature and display minimal activity in vitro. Therefore, we wanted to understand how adoptive transfer affected these cells. We believe that the in vivo environment affects the phenotypic and

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

2008-01-01

386

Numerical simulation of 2-D oblique shock-wave reflections  

Microsoft Academic Search

The transport phenomena of oblique shock-wave 2D nonstationary oblique shock-wave reflections over compressive wedges in air are studied using numerical simulation. The operator splitting method, the MacCormack scheme, the FCT modification, and adaptive grid generation techniques are used in the numerical simulation. Calculations of the oblique wall angles show that the three reflection shapes obtained by classical pseudostationary theoretical analysis

Genwang Mao

1991-01-01

387

Programmable 2D linear filter for video applications  

Microsoft Academic Search

A fully integrated 2-D linear filter including a line buffer for a 7×7 kernel is presented. To run the filter in real time at video clock frequencies, an array of pipelined carry-save adders was used as a very fast arithmetic unit. The filter chip contains 292451 transistors on a silicon area of 135 mm2. The maximum clock frequency under worst-case

WINFRIED KAMP; RONALD KUNEMUND; HEINZ SOLDNER; REINHOLD HOFER

1990-01-01

388

2-D DOA estimation method using Zernike moments  

Microsoft Academic Search

This paper proposes a computationally efficient 2-D direction-of-arrival estimation method for the single source case. In this method, the array outputs are regarded as the pixel values and then transformed into the Zernike moments (ZMs). The rotation-invariant feature of ZMs allows us to estimate azimuth angles independently of elevation angles, without performing the eigenvalue decomposition. Obtained the azimuth estimate, the

Nobuhiro Kanaya; Youji Iiguni; Hajime Maeda

2002-01-01

389

A 2D Barcode-Based Mobile Payment System  

Microsoft Academic Search

Mobile payment is very important and critical solution for mobile commerce. A user-friendly mobile payment solution is strongly needed to support mobile users to conduct secure and reliable payment transactions using mobile devices. This paper presents an innovative mobile payment system based on 2-dimensional (2D) barcodes for mobile users to improve mobile user experience in mobile payment.Unlike other existing mobile

Jerry Gao; Vijay Kulkarni; Himanshu Ranavat; Lee Chang; Hsing Mei

2009-01-01

390

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

391

Charge Transport in Chemically Doped 2D Graphene  

Microsoft Academic Search

We report on a numerical study of electronic transport in chemically doped 2D graphene materials. By using ab initio calculations, a self-consistent scattering potential is derived for boron and nitrogen substitutions, and a fully quantum-mechanical Kubo-Greenwood approach is used to evaluate the resulting charge mobilities and conductivities of systems with impurity concentration ranging within [0.5, 4.0]%. Even for a doping

Aurélien Lherbier; X. Blase; Yann-Michel Niquet; François Triozon; Stephan Roche

2008-01-01

392

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

393

Statistical analysis of quiet stance sway in 2-D.  

PubMed

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

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

2014-04-01

394

Proterozoic Geomagnetic Field Geometry  

NASA Astrophysics Data System (ADS)

Pre-Mesozoic continental reconstructions and paleoclimatic inferences from paleomagnetism rely critically upon the assumption of a time-averaged geocentric axial dipole (GAD) magnetic field. We have been testing the GAD assumption and localized non-dipole components in a different manner, by observing directional variations within the Matachewan, Mackenzie and Franklin dyke swarms. Large dyke swarms, commonly emplaced within a few million years, provide the necessary broad areal coverage to perform a test of global geomagnetic field geometry. Our analysis varies the quadrupole and octupole values of the generalized paleolatitude equation to determine a minimal angular dispersion and maximum precision of paleopoles from each dyke swarm. As a control, paleomagnetic data from the central Atlantic magmatic province (CAMP) show the sensitivities of our method to non-GAD contributions to the ancient geomagnetic field. Within the uncertainties, CAMP data are consistent with independent estimates of non-GAD contributions derived from global tectonic reconstructions (Torsvik & Van der Voo, 2002). Current results from the three Proterozoic dyke swarms all have best fits that are non-dipolar, but they differ in their optimal quadrupole/ octupole components. Treated together under the hypothesis of a static Proterozoic field geometry, the data allow a pure GAD geodynamo within the uncertainty of the method. Current results were performed using Fisherian statistics, but Bingham statistics will be included to account for the ellipticity of data.

Panzik, J. E.; Evans, D. A.

2011-12-01

395

How to turn your pump-probe instrument into a multidimensional spectrometer: 2D IR and Vis spectroscopies via pulse shaping  

PubMed Central

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

Shim, Sang-Hee; Zanni, Martin T.

2010-01-01

396

Altered expression of small heterodimer partner governs cytochrome P450 (CYP) 2D6 induction during pregnancy in CYP2D6-humanized mice.  

PubMed

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

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

2014-02-01

397

Understanding 2D projections on mirrors and on windows.  

PubMed

Representational art tries to capture a 3D world on a 2D surface, and artists often discuss this in relation to the projected image on window panes and mirrors. But are 2D projections on transparent surfaces useful to learn about projections in general? Most people are unaware of the 2D projected size of objects on the surface of mirrors. They also incorrectly expect that these projections always get smaller with distance of the target object from the mirror, and do not change with distance of the observer (when the target is stationary). In this paper we extend this result about surfaces of mirrors to surfaces of windows, and we confirm that the errors that people make are not specific to Western culture by replicating the study in China. In contrast to their errors about projections, people are more accurate at predicting how field of view will vary depending on distance of the observer from a mirror or window. To explain how this pattern of (false) beliefs can stem from experience we argue that people do not perceive projections on transparent surfaces. PMID:18534104

Bertamini, Marco; Lawson, Rebecca; Liu, Dan

2008-01-01

398

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.

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

2011-01-01

399

Comparison of 2D melting criteria in a colloidal system.  

PubMed

We use super-paramagnetic spherical particles which are arranged in a two-dimensional monolayer at a water/air interface to investigate the crystal to liquid phase transition. According to the KTHNY theory a crystal melts in thermal equilibrium by two continuous phase transitions into the isotropic liquid state with an intermediate phase, commonly known as the hexatic phase. We verify the significance of several criteria based on dynamical and structural properties to identify the crystal-hexatic and hexatic-isotropic liquid phase transitions for the same experimental data of the given setup. The criteria are the bond orientational correlation function, the Larson-Grier criterion, the 2D dynamic Lindemann parameter, the bond orientational susceptibility, the 2D Hansen-Verlet rule, the Löwen-Palberg-Simon criterion as well as a criterion based on the shape factor of Voronoi cells and Minkowski functionals. For our system with long-range repulsion, the bond order correlation function and bond order susceptibility work best to identify the hexatic-isotropic liquid transition and the 2D dynamic Lindemann parameter identifies unambiguously the hexatic-crystalline transition. PMID:23114280

Dillmann, Patrick; Maret, Georg; Keim, Peter

2012-11-21

400

Comparison of 2D melting criteria in a colloidal system  

NASA Astrophysics Data System (ADS)

We use super-paramagnetic spherical particles which are arranged in a two-dimensional monolayer at a water/air interface to investigate the crystal to liquid phase transition. According to the KTHNY theory a crystal melts in thermal equilibrium by two continuous phase transitions into the isotropic liquid state with an intermediate phase, commonly known as the hexatic phase. We verify the significance of several criteria based on dynamical and structural properties to identify the crystal-hexatic and hexatic-isotropic liquid phase transitions for the same experimental data of the given setup. The criteria are the bond orientational correlation function, the Larson-Grier criterion, the 2D dynamic Lindemann parameter, the bond orientational susceptibility, the 2D Hansen-Verlet rule, the Löwen-Palberg-Simon criterion as well as a criterion based on the shape factor of Voronoi cells and Minkowski functionals. For our system with long-range repulsion, the bond order correlation function and bond order susceptibility work best to identify the hexatic-isotropic liquid transition and the 2D dynamic Lindemann parameter identifies unambiguously the hexatic-crystalline transition.

Dillmann, Patrick; Maret, Georg; Keim, Peter

2012-11-01

401

An Intercomparison of 2-D Models Within a Common Framework  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

402

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

403

High precision calibration for 2D optical standard  

NASA Astrophysics Data System (ADS)

Photomask is a kind of 2-D optical standard with etched orthogonal coordinates made of a glass substrate chrominged or filmed with other metal. In order to solve the problems of measurement and traceability of ultra precision photomasks used in advanced manufacturing industry, 2-D photomask optical standard was calibrated in high precision laser two coordinate standard device. A high precision differential laser interferometer system was used for a length standard, a high magnification optical micro vision system was used for precision optical positioning feedback. In this paper, a image measurement model was purposed; A sampling window auto identification algorithm was designed. Grid stripe image could be identified and aimed at automatically by this algorithm. An edge detection method based on bidirection progressive scanning and 3-sigma rule for eliminating outliers in sampling window was found. Dirty point could be removed with effect. Edge detection error could be lowered. By this means, the measurement uncertainty of 2-D optical standard's ruling span was less than 0.3 micrometer (k=2).

Sun, Shuanghua; Gan, Xiaochuan; Xue, Zi; Ye, Xiaoyou; Wang, Heyan; Gao, Hongtang

2012-10-01

404

Damping in 2D and 3D dilute Bose gases  

NASA Astrophysics Data System (ADS)

Damping in two-dimensional (2D) and 3D dilute gases is investigated using both the hydrodynamical approach and the Hartree-Fock-Bogoliubov (HFB) approximation. We found that both methods are good for Beliaev damping at zero temperatures and Landau damping at very low temperatures. However, at high temperatures, the hydrodynamical approach overestimates the Landau damping and HFB gives a precise asymptotic behavior. This result shows that the comparison of the theoretical calculation using the hydrodynamical approach and the experimental data for high temperatures by Vincent Liu (1997 Phys. Rev. Lett. 79 4056) is not valid. For 2D systems, we show that the Beliaev damping rate is proportional to k3 and the Landau damping rate is proportional to T2 for low temperatures and to T for high temperatures. We also show that in 2D the hydrodynamical approach gives the same result for zero temperature and for low temperature as HFB, but overestimates the Landau damping for high temperatures.

Chung, Ming-Chiang; Bhattacherjee, Aranya B.

2009-12-01

405

Extension of the 3-D range migration algorithm to cylindrical and spherical scanning geometries  

Microsoft Academic Search

A near field three-dimensional (3-D) synthetic-aperture radar (SAR) algorithm specially tailored for cylindrical and spherical scanning geometries is presented. An imaging system with 3-D capability can be implemented by using a stepped-frequency radar which synthesizes a two-dimensional (2-D) aperture. Typical scanning geometries commonly used are planar, cylindrical, and spherical. The 3-D range migration algorithm (RMA) can be readily used with

Joaquim Fortuny-Guasch; Juan M. Lopez-Sanchez

2001-01-01

406

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

407

Migrating from 2D to 3D in "Autograph"  

ERIC Educational Resources Information Center

With both "Cabri" and "Autograph" now venturing into 3D, the dimension that previously was only demonstrated in the classroom with a lot of arm waving and crude wire cages can now be explored dynamically on screen. "Cabri 3D" concentrates on constructions, using the principles of Euclidian geometry, whereas "Autograph" creates objects using a…

Butler, Douglas

2006-01-01

408

Laboratory experiments on stratified and rotating turbulence 2D structure  

Microsoft Academic Search

Oceanic and atmospheric flows may be considered as turbulent motions under the constraints of geometry, stratification and rotation. At large scales these flows tend to be along isopycnal surfaces due to the combined effects of the very low aspect ratio of the flows (the motion is confined to thin layers of fluid) and the existence of stable density stratification. The

J. M. Redondo; A. Matulka

2009-01-01

409

Infrared spectra of ethylene clusters: (C2D4)2 and (C2D4)3.  

PubMed

Spectra of ethylene dimers and trimers are studied in the ?(11) fundamental band region of C(2)D(4) (?2200 cm(-1)) using a tuneable quantum cascade laser to probe a pulsed supersonic slit jet expansion. The dimer spectrum is that of a prolate symmetric top perpendicular band, with a distinctive appearance because the A rotational constant is almost exactly equal to six times the B constant. The analysis supports the previously determined cross-shaped dimer structure with D(2d) symmetry. An ethylene trimer has not previously been observed with rotational resolution. The spectrum is that of an oblate symmetric top parallel band. It leads to a proposed trimer structure which is barrel shaped and has C(3h) or C(3) symmetry, with the ethylene monomer C-C axes approximately aligned along the trimer symmetry axis. PMID:22588171

Rezaei, M; Michaelian, K H; McKellar, A R W; Moazzen-Ahmadi, N

2012-06-21

410

The cytochrome P450 2D6 (CYP2D6) enzyme polymorphism: Screening costs and influence on clinical outcomes in psychiatry  

Microsoft Academic Search

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

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

1996-01-01

411

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

PubMed Central

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

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

2013-01-01

412

A nonrigid kernel-based framework for 2D-3D pose estimation and 2D image segmentation.  

PubMed

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

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

2011-06-01

413

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 Å ± 0.5 Å, twist angle ?12 = 5° ± 5°), which differs from the conformation of such adjacent bases in duplex DNA. These experiments establish UV-2D FS as a method for examining the local conformations of an adjacent pair of fluorescent nucleotides substituted into specific DNA or RNA constructs, which will serve as a powerful probe to interpret, in structural terms, biologically significant local conformational changes within the nucleic acid framework of protein-nucleic acid complexes.

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

2013-01-01

414

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

415

Strong Localization of a Photon at the Intersection of the Phase Slips in 2D Photonic Crystal with Incomplete Bandgap  

NASA Astrophysics Data System (ADS)

One of the original motivations for the intensive study of photonic crystals was creating conditions for strong localization of light [1]. Introducing a point defect into photonic crystal gives rise to a localized in-gap mode bound to the defect. We demonstrate that strong localization of light can be achieved in 2D rectangular photonic crystal without a complete bandgap. The necessary conditions for localization are: (a) two phase slips along the major axes; (b) ``magic'' geometry of a unit cell, for which the leakage of the localized mode into continuum is suppressed. For the simplest geometry - a square lattice of cylinders - magic cylinder radius is 43.10 percent of the lattice period. For this geometry, even with a small contrast of dielectric constant the quality factor of the localized mode, bound to the intersection of the phase slips exceeds 10^6. Conditions for 3D magic geometry in FCC crystals are established. This work was supported by the Petroleum Research Fund under Grant No. 37890-AC6. [1] S. John, Phys. Rev. Lett. 58, 2486 (1987).

Apalkov, V. M.; Raikh, M. E.

2003-03-01

416

Null twisted geometries  

NASA Astrophysics Data System (ADS)

We define and investigate a quantization of null hypersurfaces in the context of loop quantum gravity on a fixed graph. The main tool we use is the parametrization of the theory in terms of twistors, which has already proved useful in discussing the interpretation of spin networks as the quantization of twisted geometries. The classical formalism can be extended in a natural way to null hypersurfaces, with the Euclidean polyhedra replaced by null polyhedra with spacelike faces, and SU(2) by the little group ISO(2). The main difference is that the simplicity constraints present in the formalism are all first class, and the symplectic reduction selects only the helicity subgroup of the little group. As a consequence, information on the shapes of the polyhedra is lost, and the result is a much simpler, Abelian geometric picture. It can be described by a Euclidean singular structure on the two-dimensional spacelike surface defined by a foliation of spacetime by null hypersurfaces. This geometric structure is naturally decomposed into a conformal metric and scale factors, forming locally conjugate pairs. Proper action-angle variables on the gauge-invariant phase space are described by the eigenvectors of the Laplacian of the dual graph. We also identify the variables of the phase space amenable to characterize the extrinsic geometry of the foliation. Finally, we quantize the phase space and its algebra using Dirac's algorithm, obtaining a notion of spin networks for null hypersurfaces. Such spin networks are labeled by SO(2) quantum numbers and are embedded nontrivially in the unitary, infinite-dimensional irreducible representations of the Lorentz group.

Speziale, Simone; Zhang, Mingyi

2014-04-01

417

New results in 2-D systems theory, part II: 2-D state-space models—Realization and the notions of controllability, observability, and minimality  

Microsoft Academic Search

In this part, a comparison between the different state-space models is presented. We discuss proper definitions of state, controllability and observability and their relations to minimality of 2-D systems. We also present new circuit realizations and 2-D digital filter hardware implementation of 2-D transfer functions.

Sun-Yuan Kung; B. C. Levy; M. Morf; T. Kailath

1977-01-01

418

DRC2: A code with specialized applications for coupling localized Monte Carlo adjoint calculations with fluences from two-dimensional R-Z discrete ordinates air-over-ground calculations  

SciTech Connect

The DRC2 code, which couples MASH or MASHX adjoint leakages with DORT 2-D discrete ordinates forward directional fluences, is described. The forward fluences are allowed to vary both axially and radially over the coupling surface, as opposed to the strictly axial variation allowed by the predecessor DRC code. Input instructions are presented along with descriptions and results from several sample problems. Results from the sample problems are used to compare DRC2 with DRC, DRC2 with DORT, and DRC2 with itself for the case of x-y dependence versus no x-y dependence of the forward fluence. The test problems demonstrate that for small systems DRC and DRC2 give essentially the same results. Some significant differences are noted for larger systems. Additionally, DRC2 results with no x-y dependence of the forward directional fluences are practically the same as those calculated by DRC.

Slater, C.O.

1992-01-01

419

Characterization and modeling of 2D-glass micro-machining by spark-assisted chemical engraving (SACE) with constant velocity  

NASA Astrophysics Data System (ADS)

Spark-assisted chemical engraving (SACE) is an unconventional micro-machining technology based on electrochemical discharge used for micro-machining nonconductive materials. SACE 2D micro-machining with constant speed was used to machine micro-channels in glass. Parameters affecting the quality and geometry of the micro-channels machined by SACE technology with constant velocity were presented and the effect of each of the parameters was assessed. The effect of chemical etching on the geometry of micro-channels under different machining conditions has been studied, and a model is proposed for characterization of the micro-channels as a function of machining voltage and applied speed.

Fatanat Didar, Tohid; Dolatabadi, Ali; Wüthrich, Rolf

2008-06-01

420

Inhibitory effects of phytochemicals on metabolic capabilities of CYP2D6(*)1 and CYP2D6(*)10 using cell-based models in vitro.  

PubMed

Aim:Herbal products have been widely used, and the safety of herb-drug interactions has aroused intensive concerns. This study aimed to investigate the effects of phytochemicals on the catalytic activities of human CYP2D6(*)1 and CYP2D6(*)10 in vitro.Methods:HepG2 cells were stably transfected with CYP2D6(*)1 and CYP2D6(*)10 expression vectors. The metabolic kinetics of the enzymes was studied using HPLC and fluorimetry.Results:HepG2-CYP2D6(*)1 and HepG2-CYP2D6(*)10 cell lines were successfully constructed. Among the 63 phytochemicals screened, 6 compounds, including coptisine sulfate, bilobalide, schizandrin B, luteolin, schizandrin A and puerarin, at 100 ?mol/L inhibited CYP2D6(*)1- and CYP2D6(*)10-mediated O-demethylation of a coumarin compound AMMC by more than 50%. Furthermore, the inhibition by these compounds was dose-dependent. Eadie-Hofstee plots demonstrated that these compounds competitively inhibited CYP2D6(*)1 and CYP2D6(*)10. However, their Ki values for CYP2D6(*)1 and CYP2D6(*)10 were very close, suggesting that genotype-dependent herb-drug inhibition was similar between the two variants.Conclusion:Six phytochemicals inhibit CYP2D6(*)1 and CYP2D6(*)10-mediated catalytic activities in a dose-dependent manner in vitro. Thus herbal products containing these phytochemicals may inhibit the in vivo metabolism of co-administered drugs whose primary route of elimination is CYP2D6. PMID:24786236

Qu, Qiang; Qu, Jian; Han, Lu; Zhan, Min; Wu, Lan-Xiang; Zhang, Yi-Wen; Zhang, Wei; Zhou, Hong-Hao

2014-05-01

421

Human erythrocytes analyzed by generalized 2D Raman correlation spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

422

Efficient 2D inversion of long ERT sections  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

423

Progress in 2D photonic crystal Fano resonance photonics  

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

424

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

425

Superradiance and synchronization of 2D spaser array  

NASA Astrophysics Data System (ADS)

Recently [E. S. Andrianov et al. Phys. Rev. B, 85, 165419 (2012)] it has been shown that a 1D chain of spasers may be synchronized via dipole-dipole interaction of quantum dots with plasmonic nanoparticles of neighboring spasers. We demonstrate that the same mechanism can synchronize a 2D array of spasers too, so that dipole moments of all nanoparticles oscillate in phase and in parallel to the array plane. This results in supperradiance in the direction perpendicular to the plane. Futhermore, the increase of the number of spasers N results in narrowing of the radiation pattern. Certainly, the intensity is restricted by power of pumping.

Zyablovsky, A. A.; Dorofeenko, A. V.; Vinogradov, A. P.; Andrianov, E. S.; Pukhov, A. A.; Lisyansky, A. A.

2012-09-01

426

Spontaneous bending of 2D molecular bottle-brush.  

PubMed

Using a scaling approach we consider a 2D comb copolymer brush under bending deformations. We show that the rectilinear brush is locally stable and can be characterized by a persistence length lambda increasing with the molecular weight of grafting side chains as lambda approximately M3. A bending instability due to redistribution of the side chains appears in the non-linear regime where bending is strong. Arguments are presented that the brush conformations consist of alternating rectilinear and bent sections corresponding to the different free-energy minima. PMID:16733644

Subbotin, A; de Jong, J; ten Brinke, G

2006-05-01

427

2D Simulation and Validation of Rotary Tube Piercing Process  

NASA Astrophysics Data System (ADS)

The aim of this work is to design and to improve a FEM model able to correctly define the influence of the parameters affecting the hole formation during the rotary piercing process (Mannesmann process). The software used to perform the simulations was a commercial FEM code, Deform 2D. The technological data introduced in the simulative model have been furnished by TENARIS-DALMINE S.p.A. Company, partner in this research. The results obtained in this research have been considered valid and helpful by the company.

Ceretti, E.; Giardini, C.; Brisotto, F.

2004-06-01

428

PARCEQ2D heat transfer grid sensitivity analysis  

NASA Technical Reports Server (NTRS)

The material presented in this paper is an extension of two-dimensional Aeroassist Flight Experiment (AFE) results shown previously. This study has focused on the heating rate calculations to the AFE obtained from an equilibrium real gas code, with attention placed on the sensitivity of grid dependence and wall temperature. Heat transfer results calculated by the PARCEQ2D code compare well with those computed by other researchers. Temperature convergence in the case of kinetic transport has been accomplished by increasing the wall temperature gradually from 300 K to the wall temperature of 1700 K.

Saladino, Anthony J.; Praharaj, Sarat C.; Collins, Frank G.

1991-01-01

429

Quantifying Therapeutic and Diagnostic Efficacy in 2D Microvascular Images  

NASA Technical Reports Server (NTRS)

VESGEN is a newly automated, user-interactive program that maps and quantifies the effects of vascular therapeutics and regulators on microvascular form and function. VESGEN analyzes two-dimensional, black and white vascular images by measuring important vessel morphology parameters. This software guides the user through each required step of the analysis process via a concise graphical user interface (GUI). Primary applications of the VESGEN code are 2D vascular images acquired as clinical diagnostic images of the human retina and as experimental studies of the effects of vascular regulators and therapeutics on vessel remodeling.

Parsons-Wingerter, Patricia; Vickerman, Mary B.; Keith, Patricia A.

2009-01-01

430

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

431

Conformal field theory of critical Casimir interactions in 2D  

NASA Astrophysics Data System (ADS)

Thermal fluctuations of a critical system induce long-ranged Casimir forces between objects that couple to the underlying field. For two-dimensional (2D) conformal field theories (CFT) we derive an exact result for the Casimir interaction between two objects of arbitrary shape, in terms of 1) the free energy of a circular ring whose radii are determined by the mutual capacitance of two conductors with the objects' shape; and 2) a purely geometric energy that is proportional to the conformal charge of the CFT, but otherwise super-universal in that it depends only on the shapes and is independent of boundary conditions and other details.

Bimonte, G.; Emig, T.; Kardar, M.

2013-10-01

432

Rotational Invariance of the 2d Spin - Spin Correlation Function  

NASA Astrophysics Data System (ADS)

At the critical temperature in the 2d Ising model on the square lattice, we establish the rotational invariance of the spin-spin correlation function using the asymptotics of the spin-spin correlation function along special directions (McCoy and Wu in the two dimensional Ising model. Harvard University Press, Cambridge, 1973) and the finite difference Hirota equation for which the spin-spin correlation function is shown to satisfy (Perk in Phys Lett A 79:3-5, 1980; Perk in Proceedings of III international symposium on selected topics in statistical mechanics, Dubna, August 22-26, 1984, JINR, vol II, pp 138-151, 1985).

Pinson, Haru

2012-09-01

433

Parallelization of the 2d Swendsen-Wang Algorithm  

NASA Astrophysics Data System (ADS)

We implemented a parallel Swendsen-Wang algorithm for a 2D Ising system without magnetization in a host-node programming model. The simulations were performed on the Intel Hypercube IPSC/860. Our maximum number of updates/s on 32 nodes ist three times as high as in the implementation by Stauffer and Kertész on the same machine. With 32 processors we reach half the speed of the simulations by Tamayo and Flanigan on 256 nodes of a CM5. We discuss the non-equilibrium relaxation for the energy and the magnetization.

Hackl, R.; Matuttis, H.-G.; Singer, J. M.; Husslein, Th.; Morgenstern, I.

434

Spin relaxation anisotropy: microscopic mechanisms for 2D systems  

NASA Astrophysics Data System (ADS)

Low symmetry of two-dimensional (2D) semiconductor systems results in a dependence of the spin relaxation times on the spin orientation relative to crystallographic directions. It is demonstrated that a microscopic reason for this anisotropy is an interference of structure inversion asymmetry (SIA) and bulk inversion asymmetry (BIA). For the D'yakonov-Perel' spin relaxation mechanism the anisotropy is due to SIA and BIA interference in the spin splitting of energy spectrum. In the case of the Elliott-Yafet mechanism the spin relaxation anisotropy is caused by the interference of SIA and BIA in the spin-flip scattering probability.

Averkiev, N. S.; Golub, L. E.

2008-11-01

435

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

436

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.

437

Characterization and modeling of 2D-glass micro-machining by spark-assisted chemical engraving (SACE) with constant velocity  

Microsoft Academic Search

Spark-assisted chemical engraving (SACE) is an unconventional micro-machining technology based on electrochemical discharge used for micro-machining nonconductive materials. SACE 2D micro-machining with constant speed was used to machine micro-channels in glass. Parameters affecting the quality and geometry of the micro-channels machined by SACE technology with constant velocity were presented and the effect of each of the parameters was assessed. The

Tohid Fatanat Didar; Ali Dolatabadi; Rolf Wüthrich

2008-01-01

438

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; Daniël De Zutter

2000-01-01

439

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

440

Tardive dyskinesia and debrisoquine 4-hydroxylase (CYP2D6) genotype in Japanese schizophrenics  

Microsoft Academic Search

Previous studies have shown that many neuroleptics are metabolized by debrisoquine 4-hydrolase (CYP2D6), which exhibits genetic polymorphisms. In Oriental populations, poor metabolizers (PMs) with a lack of CYP2D6 activity are rare, although the CYP2D6* 10 allele, which is associated with decreased CYP2D6 activity, is commonly found. The authors examined the relationship between tardive dyskinesia (TD) and CYP2D6 polymorphisms, including the

Osamu Ohmori; Takashi Suzuki; Hideki Kojima; Takahiro Shinkai; Takeshi Terao; Takashi Mita; Kazuhiko Abe

1998-01-01

441

Parallel 2D Graded Guaranteed Quality Delaunay Mesh Refinement  

Microsoft Academic Search

Summary. We develop a theoretical framework for constructing guaranteed qual- ity Delaunay meshes in parallel for general two-dimensional geometries. This paper presents a new approach for constructing graded meshes, i.e., meshes with element size controlled by a user-defined criterion. The sequential Delaunay refinement algo- rithms are based on inserting points at the circumcenters of triangles of poor quality or unacceptable

Andrey N. Chernikov; Nikos Chrisochoides

2005-01-01

442

Design and cost drivers in 2-D braiding  

NASA Technical Reports Server (NTRS)

Fundamentally, the braiding process is a highly efficient, low cost method for combining single yarns into circumferential shapes, as evidenced by the number of applications for continuous sleeving. However, this braiding approach cannot fully demonstrate that it can drastically reduce the cost of complex shape structural preforms. Factors such as part geometry, machine design and configuration, materials used, and operating parameters are described as key cost drivers and what is needed to minimize their effect on elevating the cost of structural braided preforms.

Morales, Alberto

1993-01-01

443

2D invariant object recognition using Log-Polar transform  

Microsoft Academic Search

Object recognition is an essential task in many image processing applications. Although object appears as three-dimensional in real world, they are usually perceived as two-dimensional in digital image or video. In most cases, major problems in recognizing objects lie on the two-dimensional geometry changes in object appearances. This paper presents an innovative template matching based object recognition method that is

Rittavee Matungka; Yuan F. Zheng; Robert L. Ewing

2008-01-01

444

View Dependent Mesh Streaming based on Geometry Image and JPEG 2000 Standard  

Microsoft Academic Search

Therefore, in this paper, we propose a new mesh streaming method by utilizing the benefits of JPEG 2000. This method takes the advantage of the fact that a 3D model or a 3D scene can be represented by a geometry image (3). This could reduce the prob- lem of 3D mesh streaming and transfer it to 2D image streaming. There

Nein-Hsiung Lin; Ting-Hao Huang; Bing-Yu Chen; Yung-Yu Chuang; Ming Ouhyoung

445

Slab geometry depending on absolute velocities and possibilities of cyclicity, Insights from numerical modelling  

Microsoft Academic Search

Recent analogical models of Heuret et al (2007) and Guillaume et al (2009) showed that the kinematical and mechanical role of the overriding plate is crucial for the slab geometry. We used Hassani et al (1997) 2D finite element numerical code to model subduction with parameters close to analogue models conditions. Our results are coherent with considered previous analogue models.

Gibert Gaelle; Hassani Riad; Tric Emmanuel; Monfret Tony

2010-01-01

446

Marginal fluctuations as instantons on M2/D2-branes  

NASA Astrophysics Data System (ADS)

We introduce some (anti-) M/D-branes through turning on the corresponding field strengths of the 11- and 10-dimensional supergravity theories over spaces, where we use and for the internal spaces. Indeed, when we add M2/D2-branes on the same directions with the near horizon branes of the Aharony-Bergman-Jafferis-Maldacena model, all symmetries and supersymmetries are preserved trivially. In this case, we obtain a localized object just in the horizon. This normalizable bulk massless scalar mode is a singlet of and , and it agrees with a marginal boundary operator of the conformal dimension of . However, after performing a special conformal transformation, we see that the solution is localized in the Euclideanized space and is attributable to the included anti-M2/D2-branes, which are also necessary to ensure that there is no back-reaction. The resultant theory now breaks all supersymmetries to , while the other symmetries are so preserved. The dual boundary operator is then set up from the skew-whiffing of the representations and for the supercharges and scalars, respectively, while the fermions remain fixed in of the original theory. Besides, we also address another alternate bulk to boundary matching procedure through turning on one of the gauge fields of the full gauge group along the same lines with a similar situation to the one faced in the AdS/CFT correspondence. The latter approach covers the difficulty already faced with in the bulk-boundary matching procedure for as well.

Naghdi, M.

2014-03-01

447

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

448

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.

2013-01-01

449

2D-simulation Design of An Ignition Hohlraum  

NASA Astrophysics Data System (ADS)

Based on two-dimensinal (2D) calculations, this article describes the method by which we can design an ignition hohlraum under the conditions of capsule drive and laser energy and power limit. We use JC Code (3T Version) to simulate the coupling between laser and hohlraum and use the improved post code to obtain the x-ray drive on capsule. The study focuses onsome key problems, which do not appear in the 0D design. These problems include how to choose hohlraum gas fill density and capsule drive pulse length, how to describe the main pulse temporal behavior of laser drive, and how to tune the P2 drive asymmetry on capsule in the main pulse to zero. Laser plasma interaction (LPI) is not considered in the study because of the lack of analysis ability. But we leave sufficient margin for it. The final ignition hohlraum 2D design requires 1.4 MJ and 416 TW of laser energy and peak power, to achieve a drive temperature of 300 eV with 14% M-band photon (hv>2keV) ratio in an cylindrical target and gives a yield of about 16 MJ. The ratio of the outer beam energy over the inner beam energy is 3. About 85% laser energy converts to x-rays.

Li, Xin; Wu, Changshu; Zhao, Yiqing; Zou, Shiyang; Zheng, Wudi

2012-10-01

450

Numerical modeling of 2D wave refraction and shoaling  

NASA Astrophysics Data System (ADS)

As waves propagate into shallow water area they undergo shoaling and refraction. Refraction is a bending wave phenomenon that leads the wave crest arriving at beach directed parallel to the shoreline. Shoaling is a phenomenon of increasing wave height with decreasing water depth. Shoaling and refraction are both direct consequence of energy conservation. In this paper we solve the 2D shallow water equations using the conservative finite volume method. This scheme is non dissipative, therefore it can produce shoaling coefficient correctly. Simulation of 2D plane wave above a parallel bottom contours shows that numerical wave refraction confirms the analytical wave refraction. In this way we are convinced that our scheme can produce shoaling and refraction correctly. When a wave travels over a continental shelf and further to the beach, before breaking, the wave will experience shoaling and refraction which is not