Geometry of 2D topological field theories
Boris Dubrovin
1994-01-01
These lecture notes are devoted to the theory of equations of associativity\\u000adescribing geometry of moduli spaces of 2D topological field theories.\\u000aIntroduction. Lecture 1. WDVV equations and Frobenius manifolds. {Appendix A.}\\u000aPolynomial solutions of WDVV. {Appendix B.} Symmetriies of WDVV. Twisted\\u000aFrobenius manifolds. {Appendix C.} WDVV and Chazy equation. Affine connections\\u000aon curves with projective structure. Lecture 2. Topological
A Unified Reconstruction Algorithm for Conventional 2-D Acquisition Geometry*
A Unified Reconstruction Algorithm for Conventional 2-D Acquisition Geometry* Jiangsheng You-beam geometry, including parallel- or fan-beam collimation as a simplfied ex- ample. Compared to other harmonic for fan-beam geometry [2]. Tretiak and Metz ob- tained a FBP algorithm for projections of parallel- beam
Part I Euclidean Geometry 1 1 2D Computational Euclidean Geometry 3
Toronto, University of
Geometry 80 7.8 Documenting Degeneracies 81 7.9 Exercises 81 Part II Non-Euclidean Geometries 85 8 1DContents Preface v Part I Euclidean Geometry 1 1 2D Computational Euclidean Geometry 3 1.1 Points.5 The Geometry of the Euclidean Line E1 23 2.6 Immutability of Geometric Objects 24 2.7 Exercises 25 3 3D
GBL-2D Version 1.0: a 2D geometry boolean library.
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
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.
Non-Compact Geometries in 2D Euclidean Quantum Gravity
Gesser, Jens A
2010-01-01
This thesis discusses the worldsheet geometries in the (p,q) minimal model coupled to 2D euclidean Quantum Gravity with particular focus on non-compact geometries. We first calculate the FZZT-FZZT cylinder amplitudes for all pairs of Cardy matter states thereby generalizing the result obtained in arXiv:hep-th/0406030 and discuss the decompositions of the cylinder amplitudes in terms of solutions to the homogeneous Wheeler-DeWitt equation. We then show, that the principal ZZ boundary conditions in Liouville theory can be viewed as effective boundary conditions obtained by integrating out the matter degrees of freedom on the worldsheet. We now consider the (2,2m-1) minimal model coupled to 2D euclidean Quantum Gravity obtained in the scaling limit of dynamical triangulations, in which the mth multi-critical hyper-surface is approached and the conformal background is turned on. We show, that only one concrete realization of matter boundary condition, the (1,1) Cardy boundary condition, is obtained in this scalin...
Non-Compact Geometries in 2D Euclidean Quantum Gravity
Jens A. Gesser
2010-10-24
This thesis discusses the worldsheet geometries in the (p,q) minimal model coupled to 2D euclidean Quantum Gravity with particular focus on non-compact geometries. We first calculate the FZZT-FZZT cylinder amplitudes for all pairs of Cardy matter states thereby generalizing the result obtained in arXiv:hep-th/0406030 and discuss the decompositions of the cylinder amplitudes in terms of solutions to the homogeneous Wheeler-DeWitt equation. We then show, that the principal ZZ boundary conditions in Liouville theory can be viewed as effective boundary conditions obtained by integrating out the matter degrees of freedom on the worldsheet. We now consider the (2,2m-1) minimal model coupled to 2D euclidean Quantum Gravity obtained in the scaling limit of dynamical triangulations, in which the mth multi-critical hyper-surface is approached and the conformal background is turned on. We show, that only one concrete realization of matter boundary condition, the (1,1) Cardy boundary condition, is obtained in this scaling limit. Finally, we study the cylinder amplitude with fixed distance and provide some evidence of a transition from a FZZT-brane to a ZZ-brane on the exit loop in the limit, where the distance approaches infinity, and for particular values of the exit-boundary cosmological constant.
Facial biometrics based on 2D vector geometry
NASA Astrophysics Data System (ADS)
Malek, Obaidul; Venetsanopoulos, Anastasios; Androutsos, Dimitrios
2014-05-01
The main challenge of facial biometrics is its robustness and ability to adapt to changes in position orientation, facial expression, and illumination effects. This research addresses the predominant deficiencies in this regard and systematically investigates a facial authentication system in the Euclidean domain. In the proposed method, Euclidean geometry in 2D vector space is being constructed for features extraction and the authentication method. In particular, each assigned point of the candidates' biometric features is considered to be a 2D geometrical coordinate in the Euclidean vector space. Algebraic shapes of the extracted candidate features are also computed and compared. The proposed authentication method is being tested on images from the public "Put Face Database". The performance of the proposed method is evaluated based on Correct Recognition (CRR), False Acceptance (FAR), and False Rejection (FRR) rates. The theoretical foundation of the proposed method along with the experimental results are also presented in this paper. The experimental results demonstrate the effectiveness of the proposed method.
Cloaking of 2D particle geometries in a surface medium
NASA Astrophysics Data System (ADS)
Alexopoulos, A.; Yau, K. S. B.
2013-06-01
We theoretically examine the cloaking condition for two-dimensional particles with varying geometry embedded inside a surface medium. General solutions are obtained for multi-layer particle configurations with either all positive or partially negative constitutive parameters respectively. Cloaking of particle geometries that are large relative to the incident wavelength is demonstrated. Theoretical predictions are compared to full-wave numerical simulations for arrays of particles consisting of different geometries.
3D Geometry Projection from 2D to 3D
Jacobs, David
n n n zzz yyy xxx P Points = y x tsss tsss S 3,22,21,2 3,12,11,1 Some matrix = n n vvv uuu I 21 21 of the points in P. #12;5 First, look at 2D rotation (easier) - n n yyy xxx 21 21 ... cossin sincos coordinates. That is, it's rotated. #12;6 Simple 3D Rotation - n n n zzz yyy xxx 21 21 21 ... 100 0cossin 0
Boundary treatments for 2D elliptic mesh generation in complex geometries
Technology Transfer Automated Retrieval System (TEKTRAN)
This paper presents a boundary treatment method for 2D elliptic mesh generation in complex geometries. Corresponding to Neumann- Dirichlet boundary conditions (sliding boundary conditions), the proposed method aims at achieving orthogonal and smooth nodal distribution along irregular boundaries. In ...
Paris-Sud XI, Université de
GEOMETRY-CONSTRAINED CORONARY ARTERIES MOTION ESTIMATION FROM 2D ANGIOGRAMS - APPLICATION of coronary arteries. It exploits the geometry of acquisition to strongly constrain the problem, thereby of an angiographic exam into right or left artery tree. Index Terms-- Coronary arteries, motion estimation. 1
Stamos, Ioannis
digital photography. A system- atic way for registering 3D range scans and 2D images is thus essentialMultiview Geometry for Texture Mapping 2D Images Onto 3D Range Data Computer Vision and Pattern presents a system that integrates multiview geometry and automated 3D registration techniques for texture
Visualizing 2D Quantum Field Theory Geometry and Informatics of Mobilevision
Juriev, D V
1994-01-01
This article is devoted to some interesting geometric and informatic interpretations of peculiarities of 2D quantum field theory, which become re- vealed after its visualization. Contents. I. Geometry of Mobilevision: 1.1. Interpretational geometry and anomalous virtual realities; 1.2. Quantum projective field theory and Mobilevision; 1.3. Quantum conformal and q_R conformal field theories; quantum-field analogs of Euler-Arnold top; 1.4. Organizing MV cyberspace; 1.5. Non-Alexandrian geometry of Mobilevision. II. Informatics of Mobilevision: 2.1. Information transmission via anomalous virtual realities: AVR-photodosy; 2.2. Information transmission via intentional anomalous virtual realities: IAVR-teleaesthesy.
Numerical simulations of annular wire-array z-pinches in (x,y), (r,{theta}), and (r,z) geometries
Marder, B.M.; Sanford, T.W.L.; Allshouse, G.O.
1997-12-01
The Total Immersion PIC (TIP) code has been used in several two-dimensional geometries to understand better the measured dynamics of annular, aluminum wire-array z-pinches. The areas investigated include the formation of the plasma sheath from current-induced individual wire explosions, the effects of wire number and symmetry on the implosion dynamics, and the dependence of the Rayleigh-Taylor instability growth on initial sheath thickness. A qualitative change in the dynamics with increasing wire number was observed, corresponding to a transition between a z-pinch composed of non-merging, self-pinching individual wires, and one characterized by the rapid formation and subsequent implosion of a continuous plasma sheath. A sharp increase in radiated power with increasing wire number has been observed experimentally near this calculated transition. Although two-dimensional codes have correctly simulated observed power pulse durations, there are indications that three dimensional effects are important in understanding the actual mechanism by which these pulse lengths are produced.
Multiview Geometry for Texture Mapping 2D Images Onto 3D Range Data Lingyun Liu and Ioannis Stamos
Wolberg, George
technology with traditional digital photography. A system- atic way for registering 3D range scans and 2DMultiview Geometry for Texture Mapping 2D Images Onto 3D Range Data Ł Lingyun Liu and Ioannis 3D registration techniques for texture mapping 2D images onto 3D range data. The 3D range scans
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
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.
Probability distribution of the index in gauge theory on 2d non-commutative geometry
Hajime Aoki; Jun Nishimura; Yoshiaki Susaki
2007-10-05
We investigate the effects of non-commutative geometry on the topological aspects of gauge theory using a non-perturbative formulation based on the twisted reduced model. The configuration space is decomposed into topological sectors labeled by the index nu of the overlap Dirac operator satisfying the Ginsparg-Wilson relation. We study the probability distribution of nu by Monte Carlo simulation of the U(1) gauge theory on 2d non-commutative space with periodic boundary conditions. In general the distribution is asymmetric under nu -> -nu, reflecting the parity violation due to non-commutative geometry. In the continuum and infinite-volume limits, however, the distribution turns out to be dominated by the topologically trivial sector. This conclusion is consistent with the instanton calculus in the continuum theory. However, it is in striking contrast to the known results in the commutative case obtained from lattice simulation, where the distribution is Gaussian in a finite volume, but the width diverges in the infinite-volume limit. We also calculate the average action in each topological sector, and provide deeper understanding of the observed phenomenon.
Folded Paper Geometry from 2D Pattern and 3D Contour Damien Rohmer1,2,3
Paris-Sud XI, Université de
-like surfaces, not re- stricted to the convex hull of their contour points and where folds are automaticallyFolded Paper Geometry from 2D Pattern and 3D Contour Damien Rohmer1,2,3 , Marie-Paule Cani1University of Lyon, CPE Lyon. Abstract Folded paper exhibits very characteristic shapes, due to the presence
Large-eddy simulation with complex 2-D geometries using a parallel finite-element/spectral algorithm
NASA Astrophysics Data System (ADS)
Snyder, D. O.; Degrez, G.
2003-04-01
A parallel stabilized finite-element/spectral formulation is presented for incompressible large-eddy simulation with complex 2-D geometries. A unique discretization scheme is developed consisting of a streamline-upwind Petrov-Galerkin/Pressure-Stabilized Petrov-Galerkin (SUPG/PSPG) finite-element discretization in the 2-D plane with a collocated spectral/pseudospectral discretization in the out-of-plane direction. This formulation provides an efficient approach for solving 3-D flows over arbitrary 2-D geometries. Utilizing this discretization and through explicit temporal treatment of the non-linear terms, the system of equations for each Fourier mode is decoupled within each time step. A novel parallelization approach is then taken, where the computational work is partitioned in Fourier space. A validation of the algorithm is presented via comparison of results for flow past a circular cylinder with published values for Re=195, 300, and 3900.
E2GPR - Edit your geometry, Execute GprMax2D and Plot the Results!
NASA Astrophysics Data System (ADS)
Pirrone, Daniele; Pajewski, Lara
2015-04-01
In order to predict correctly the Ground Penetrating Radar (GPR) response from a particular scenario, Maxwell's equations have to be solved, subject to the physical and geometrical properties of the considered problem and to its initial conditions. Several techniques have been developed in computational electromagnetics, for the solution of Maxwell's equations. These methods can be classified into two main categories: differential and integral equation solvers, which can be implemented in the time or spectral domain. All of the different methods present compromises between computational efficiency, stability, and the ability to model complex geometries. The Finite-Difference Time-Domain (FDTD) technique has several advantages over alternative approaches: it has inherent simplicity, efficiency and conditional stability; it is suitable to treat impulsive behavior of the electromagnetic field and can provide either ultra-wideband temporal waveforms or the sinusoidal steady-state response at any frequency within the excitation spectrum; it is accurate and highly versatile; and it has become a mature and well-researched technique. Moreover, the FDTD technique is suitable to be executed on parallel-processing CPU-based computers and to exploit the modern computer visualisation capabilities. GprMax [1] is a very well-known and largely validated FDTD software tool, implemented by A. Giannopoulos and available for free public download on www.gprmax.com, together with examples and a detailled user guide. The tool includes two electromagnetic wave simulators, GprMax2D and GprMax3D, for the full-wave simulation of two-dimensional and three-dimensional GPR models. In GprMax, everything can be done with the aid of simple commands that are used to define the model parameters and results to be calculated. These commands need to be entered in a simple ASCII text file. GprMax output files can be stored in ASCII or binary format. The software is provided with MATLAB functions, which can be employed to import synthetic data created by GprMax using the binary-format option into MATLAB, in order to be processed and/or visualized. Further MATLAB procedures for the visualization of GprMax synthetic data have been developed within the COST Action TU1208 [2] and are available for free public download on www.GPRadar.eu. The current version of GprMax3D is compiled with OpenMP, supporting multi-platform shared memory multiprocessing which allows GprMax3D to take advantage of multiple cores/CPUs. GprMax2D, instead, exploits a single core when executed. E2GPR is a new software tool, available free of charge for both academic and commercial use, conceived to: 1) assist in the creation, modification and analysis of GprMax2D models, through a Computer-Aided Design (CAD) system; 2) allow parallel and/or distributed computing with GprMax2D, on a network of computers; 3) automatically plot A-scans and B-scans generated by GprMax2D. The CAD and plotter parts of the tool are implemented in Java and can run on any Java Virtual Machine (JVM) regardless of computer architecture. The part of the tool devoted to supporting parallel and/or distributed computing, instead, requires the set up of a Web-Service (on a server emulator or server); in fact, it is currently configured only for Windows Server and Internet Information Services (IIS). In this work, E2GPR is presented and examples are provided which demonstrate its use. The tool can be currently obtained by contacting the authors. It will soon be possible to download it from www.GPRadar.eu. Acknowledgement This work is a contribution to the COST Action TU1208 'Civil Engineering Applications of Ground Penetrating Radar.' The authors thank COST for funding the Action TU1208. References [1] A. Giannopoulos, 'Modelling ground penetrating radar by GprMax,' Construction and Building Materials, vol. 19, pp. 755-762, 2005. [2] L. Pajewski, A. Benedetto, X. Dérobert, A. Giannopoulos, A. Loizos, G. Manacorda, M. Marciniak, C. Plati, G. Schettini, I. Trinks, "Applications of Ground Penetrating Radar in Civil Enginee
The differences in the development of Rayleigh-Taylor instability in 2D and 3D geometries
NASA Astrophysics Data System (ADS)
Kuchugov, P. A.; Rozanov, V. B.; Zmitrenko, N. V.
2014-06-01
Results are presented from theoretical analysis and numerical simulations aimed to clarify specific features of Rayleigh-Taylor instability in 2D and 3D geometries. Two series of simulations, one with an isolated single-mode perturbation of the interface and the other with a random density perturbation, were performed. It is shown that the relative evolutions of integral characteristics for the first and the second series are different in 2D and 3D geometries. An attempt is made to interpret this result in the framework of the previously developed evolutionary approach based on the concept of the "critical age" of the perturbation (where, by the age is meant the product of the wavenumber and amplitude). The critical age corresponds to the destruction of the main mushroom-like structure formed during the development of Rayleigh-Taylor instability due to the onset of the secondary Kelvin-Helmholtz instability.
Combining 2D and 3D hand geometry features for biometric verification
Vivek Kanhangad; Ajay Kumar; David Zhang
2009-01-01
Traditional hand geometry based personal verification systems offer limited performance and therefore suitable only for small scale applications. This paper investigates a new approach to achieve performance improvement for hand geometry systems by simultaneously acquiring three dimensional features from the presented hands. The proposed system utilizes a laser based 3D digitizer to acquire registered intensity and range images of the
Effects of Training Method and Gender on Learning 2D/3D Geometry
ERIC Educational Resources Information Center
Khairulanuar, Samsudin; Nazre, Abd Rashid; Jamilah, H.; Sairabanu, Omar Khan; Norasikin, Fabil
2010-01-01
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…
The contact geometry in a 2D ?c-Si:H p-i-n imager
J Martins; F Sousa; M Fernandes; P Louro; A Maçarico; M Vieira
2000-01-01
A two-dimensional imager has been designed and produced based on ?c-Si:H material. The basic building block for the sensor element is a TCO\\/?c-p-i-n Si:H photodiode with two front metal contacts and a back TCO transparent one. A scan-out process obtains the image. The effect of the contact geometry on the sensor output characteristics (linearity, distortion, sensitivity and signal-to-noise ratio) were
Determining Transition State Geometries in Liquids Using 2D-IR
Harris, Charles; Cahoon, James F.; Sawyer, Karma R.; Schlegel, Jacob P.; Harris, Charles B.
2007-12-11
Many properties of chemical reactions are determined by the transition state connecting reactant and product, yet it is difficult to directly obtain any information about these short-lived structures in liquids. We show that two-dimensional infrared (2D-IR) spectroscopy can provide direct information about transition states by tracking the transformation of vibrational modes as a molecule crossed a transition state. We successfully monitored a simple chemical reaction, the fluxional rearrangement of Fe(CO)5, in which the exchange of axial and equatorial CO ligands causes an exchange of vibrational energy between the normal modes of the molecule. This energy transfer provides direct evidence regarding the time scale, transition state, and mechanism of the reaction.
A numerical study on the thermal initiation of a confined explosive in 2-D geometry.
Aydemir, Erdo?an; Ulas, Abdullah
2011-02-15
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
NASA Astrophysics Data System (ADS)
Shah, Jainil; Pachon, Jan H.; Madhav, Priti; Tornai, Martin P.
2011-03-01
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.
R. Ahl Laamara; A. Belhaj; L. B. Drissi; E. H. Saidi
2007-01-01
Motivated by studies on 4d black holes and q-deformed 2d Yang–Mills theory, and borrowing ideas from compact geometry of the blowing up of affine ADE singularities, we build a class of local Calabi–Yau threefolds (CY3) extending the local 2-torus model O(m)?O(?m)?T2 considered in [C. Gomez, S. Montanez, A comment on quantum distribution functions and the OSV conjecture, hep-th\\/0608162] to test
NASA Astrophysics Data System (ADS)
Huerta-Viga, Adriana; Amirjalayer, Saeed; Domingos, Sérgio R.; Meuzelaar, Heleen; Rupenyan, Alisa; Woutersen, Sander
2015-06-01
Salt bridges play an important role in protein folding and in supramolecular chemistry, but they are difficult to detect and characterize in solution. Here, we investigate salt bridges between glutamate (Glu-) and arginine (Arg+) using two-dimensional infrared (2D-IR) spectroscopy. The 2D-IR spectrum of a salt-bridged dimer shows cross peaks between the vibrational modes of Glu- and Arg+, which provide a sensitive structural probe of Glu-⋯Arg+ salt bridges. We use this probe to investigate a ?-turn locked by a salt bridge, an ?-helical peptide whose structure is stabilized by salt bridges, and a coiled coil that is stabilized by intra- and intermolecular salt bridges. We detect a bidentate salt bridge in the ?-turn, a monodentate one in the ?-helical peptide, and both salt-bridge geometries in the coiled coil. To our knowledge, this is the first time 2D-IR has been used to probe tertiary side chain interactions in peptides, and our results show that 2D-IR spectroscopy is a powerful method for investigating salt bridges in solution.
Huerta-Viga, Adriana; Amirjalayer, Saeed; Domingos, Sérgio R; Meuzelaar, Heleen; Rupenyan, Alisa; Woutersen, Sander
2015-06-01
Salt bridges play an important role in protein folding and in supramolecular chemistry, but they are difficult to detect and characterize in solution. Here, we investigate salt bridges between glutamate (Glu(-)) and arginine (Arg(+)) using two-dimensional infrared (2D-IR) spectroscopy. The 2D-IR spectrum of a salt-bridged dimer shows cross peaks between the vibrational modes of Glu(-) and Arg(+), which provide a sensitive structural probe of Glu(-)?Arg(+) salt bridges. We use this probe to investigate a ?-turn locked by a salt bridge, an ?-helical peptide whose structure is stabilized by salt bridges, and a coiled coil that is stabilized by intra- and intermolecular salt bridges. We detect a bidentate salt bridge in the ?-turn, a monodentate one in the ?-helical peptide, and both salt-bridge geometries in the coiled coil. To our knowledge, this is the first time 2D-IR has been used to probe tertiary side chain interactions in peptides, and our results show that 2D-IR spectroscopy is a powerful method for investigating salt bridges in solution. PMID:26049464
Shapiro, A.B.
1983-08-01
The computer code FACET calculates the radiation geometric view factor (alternatively called shape factor, angle factor, or configuration factor) between surfaces for axisymmetric, two-dimensional planar and three-dimensional geometries with interposed third surface obstructions. FACET was developed to calculate view factors for input to finite-element heat-transfer analysis codes. The first section of this report is a brief review of previous radiation-view-factor computer codes. The second section presents the defining integral equation for the geometric view factor between two surfaces and the assumptions made in its derivation. Also in this section are the numerical algorithms used to integrate this equation for the various geometries. The third section presents the algorithms used to detect self-shadowing and third-surface shadowing between the two surfaces for which a view factor is being calculated. The fourth section provides a user's input guide followed by several example problems.
Gordon Petrie; Nektarios Vlahakis; Kanaris Tsinganos
2001-11-28
We present a systematic method for constructing two-dimensional magnetohydrodynamic equilibria with compressible flow in Cartesian geometry. This systematic method has already been developed in spherical geometry and applied in modelling solar and stellar winds and outflows (Vlahakis & Tsinganos,1998) but is derived here in Cartesian geometry in the context of the solar atmosphere for the first time. Using the method we find several new classes of solutions, some of which generalise known solutions, including the Kippenhahn & Schl\\"uter (1957) and Hood & Anzer (1990) solar prominence models and the Tsinganos, Surlantzis & Priest (1993) coronal loop model with flow, and some of which are completely new. Having developed the method in full and summarised the several classes of solutions, we explore in a some detail one of the classes to illustrate the general construction method. From one of the new classes of solutions we calculate two loop-like solutions, one of which is the first exact two-dimensional magnetohydrodynamic equilibrium with trans-Alfv\\'enic flow.
Fevotte, F.; Lathuiliere, B. [EDF R and D (France)
2013-07-01
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)
On the Effect of Apex Geometry on Wall Shear Stress and Pressure in a 2-D Arterial Bifurcation
NASA Astrophysics Data System (ADS)
Robertson, Anne; Haljasmaa, Igor; Galdi, Giovanni
2000-11-01
There is strong evidence to support the hypothesis that vascular geometry plays an important role in the initiation and development of cerebral aneurysms as well as other vascular diseases through its influence on hemodynamics. Cerebral aneurysms are nearly always found at arterial bifurcations in and near the Circle of Willis. It is commonly believed that the cause of initiation and development of cerebral aneurysms is at least indirectly related to the effect of hemodynamic wall pressure and shear stress on the arterial tissue at arterial bifurcations. In this work, we use analytical and numerical approaches to investigate the hypothesis that local geometric factors can have a significant impact on the magnitude and spatial gradients of wall pressure and shear stress at the apex of arterial bifurcations. We find that sharp corners such as those at arterial bifurcations and the juncture between grafted vessels can be a source of localized high wall pressure and shear stress. In fact, it can be shown analytically that perfectly sharp corners (zero radius of curvature) will lead to unbounded magnitudes of shear stress and pressure . As the radius of curvature is increased (the corner is rounded), the maximum in magnitude in wall shear stress shifts away from the apex to the lateral sides of the bifurcation. Significantly, the unbounded pressure and shear stress at perfectly sharp corners are unrelated to the fluid inertia. As shown here, the large values of pressure and shear stress which have previously been reported in studies in sharp corner models (zero radius of curvature) are grid dependent approximations for unbounded pressure and shear stress.
NSDL National Science Digital Library
Rusin, Dave
A short article designed to provide an introduction to geometry, including classical Euclidean geometry and synthetic (non-Euclidean) geometries; analytic geometry; incidence geometries (including projective planes); metric properties (lengths and angles); and combinatorial geometries such as those arising in finite group theory. Many results in this area are basic in either the sense of simple, or useful, or both. History; applications and related fields and subfields; textbooks, reference works, and tutorials; software and tables; other web sites with this focus.
GRAPHICS PROGRAMMING Section B Java 2D
Hill, Gary
GRAPHICS PROGRAMMING Section B Java 2D 20 - Graphics2D: Introduction 21 - Graphics2D: Shapes 22 2D: General Path Curves 29 - Graphics 2D: Constructive Area Geometry Gary Hill December 2003 Java 2 Java initially through the Abstract Window Toolkit, which was extended to include swing, shortly
Kolkoori, Sanjeevareddy; Chitti Venkata, Krishnamurthy; Balasubramaniam, Krishnan
2015-01-01
This article presents an analytical approach for simulation of ultrasonic diffracted wave signals from cracks in two-dimensional geometries based on a novel Huygens-Fresnel Diffraction Model (HFDM). The model employs the frequency domain far-field displacement expressions derived by Miller and Pursey in 2D for a line source located on the free surface boundary of a semi-infinite elastic medium. At each frequency in the bandwidth of a pulsed excitation, the complex diffracted field is obtained by summation of displacements due to the unblocked virtual sources located in the section containing a vertical crack. The time-domain diffracted wave signal amplitudes in a general isotropic solid are obtained by standard Fast Fourier Transform (FFT) procedures. The wedge based finite aperture transducer refracted beam profiles were modelled by treating the finite dimension transducer as an array of line sources. The proposed model is able to evaluate back-wall signal amplitude and lateral wave signal amplitude, quantitatively. The model predicted range-dependent diffracted amplitudes from the edge of a bottom surface-breaking crack in the isotropic steel specimen were compared with Geometrical Theory of Diffraction (GTD) results. The good agreement confirms the validity of the HFDM method. The simulated ultrasonic time-of-flight diffraction (TOFD) A-scan signals for surface-breaking crack lengths 2 mm and 4 mm in a 10 mm thick aluminium specimen were compared quantitatively with the experimental results. Finally, important applications of HFDM method to the ultrasonic quantitative non-destructive evaluation are discussed. PMID:25200698
NSDL National Science Digital Library
Mr. Edwards
2010-09-29
Geometric concepts Thanks to all who have contributed to this site. Your hard work is appreciated. Geogebra Interactive manipulation of geometric figures National Library of Virtual Manipulatives Utah State University internet site with lots of math games Pythagorean Theorem Find out how the Greek philosopher figured the lengths of lines in a right triangle Triangles Build, name and see triangles in 3-D Great Geometry Play a matching game with polygons Learn to sort the different types of triangles Groovy Geometry Make different shapes and sizes ...
Self-consistent, 2D simulations of filament propagation in photoconducting switches
Rambo, P.W.; Lawson, W.S. [Lawrence Livermore National Lab., CA (United States); Capps, C.D.; Falk, R.A. [Boeing Defense and Space Group, Seattle, WA (United States)
1994-09-01
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 as field dependent impact ionization are included. The authors report filament propagation with speeds U{sub f} {approx} 10{sup 8}--10{sup 9} cm/s, much larger than the saturated carrier drift velocity, u{sup sat} {approx} 10{sup 7} cm/s. The self-consistently determined filament radius and carrier number density are typically R{sub f} {approx} 20--60 {mu}m and n{sub f} {approx} 10{sup 17}--10{sup 18} cm{sup {minus}3} respectively. Results are presented for filament propagation in systems with both uniform and nonuniform profiles of background carrier density and electric field.
Choi, Chang-Hyung; Lee, Byungjin; Kim, Jongmin; Nam, Jin-Oh; Yi, Hyunmin; Lee, Chang-Soo
2015-06-01
Polymeric microparticles with complex shapes have attracted substantial attention in many application areas because particle shape is a critical parameter to impart programmable functionalities. The formation of specific three-dimensional (3D) microstructures in a simple, scalable, and controllable manner is difficult. Here, we report the controlled fabrication of microparticles with complex 3D shapes based on the simple tuning of mold swelling and capillarity. Specifically, a photocurable solution loaded in micromolds is spatially deformed into complex shapes depending on the degree of molding swelling and capillarity, thereby producing polymeric microparticles with controlled 3D shapes upon photopolymerization. The results show that highly uniform microparticles with controlled two-dimensional (2D) and 3D shapes were fabricated from identical 2D micromolds via the simple tuning of the wetting fluids. This technique can be extended to produce highly complex microarchitectures with controlled 3D geometric domains via 2D mold designs. Finally, multicompartment microparticles with independently controlled 3D shapes for each compartment are produced by a simple combination of fabrication sequences. We envision that this strategy of producing 3D microarchitectures from easily designed simple micromolds could provide a path to new materials and new properties. PMID:25920947
NASA Astrophysics Data System (ADS)
Ouadah, S.; Stayman, J. W.; Gang, G.; Uneri, A.; Ehtiati, T.; Siewerdsen, J. H.
2015-03-01
Purpose: Robotic C-arm systems are capable of general noncircular orbits whose trajectories can be driven by the particular imaging task. However obtaining accurate calibrations for reconstruction in such geometries can be a challenging problem. This work proposes a method to perform a unique geometric calibration of an arbitrary C-arm orbit by registering 2D projections to a previously acquired 3D image to determine the transformation parameters representing the system geometry. Methods: Experiments involved a cone-beam CT (CBCT) bench system, a robotic C-arm, and three phantoms. A robust 3D-2D registration process was used to compute the 9 degree of freedom (DOF) transformation between each projection and an existing 3D image by maximizing normalized gradient information with a digitally reconstructed radiograph (DRR) of the 3D volume. The quality of the resulting "self-calibration" was evaluated in terms of the agreement with an established calibration method using a BB phantom as well as image quality in the resulting CBCT reconstruction. Results: The self-calibration yielded CBCT images without significant difference in spatial resolution from the standard ("true") calibration methods (p-value >0.05 for all three phantoms), and the differences between CBCT images reconstructed using the "self" and "true" calibration methods were on the order of 10-3 mm-1. Maximum error in magnification was 3.2%, and back-projection ray placement was within 0.5 mm. Conclusion: The proposed geometric "self" calibration provides a means for 3D imaging on general noncircular orbits in CBCT systems for which a geometric calibration is either not available or not reproducible. The method forms the basis of advanced "task-based" 3D imaging methods now in development for robotic C-arms.
2d gauge theories and generalized geometry
NASA Astrophysics Data System (ADS)
Kotov, Alexei; Salnikov, Vladimir; Strobl, Thomas
2014-08-01
We show that in the context of two-dimensional sigma models minimal coupling of an ordinary rigid symmetry Lie algebra g leads naturally to the appearance of the "generalized tangent bundle" M? TM? T * M by means of composite fields. Gauge transformations of the composite fields follow the Courant bracket, closing upon the choice of a Dirac structure D ? M (or, more generally, the choide of a "small Dirac-Rinehart sheaf" ), in which the fields as well as the symmetry parameters are to take values. In these new variables, the gauge theory takes the form of a (non-topological) Dirac sigma model, which is applicable in a more general context and proves to be universal in two space-time dimensions: a gauging of g of a standard sigma model with Wess-Zumino term exists, iff there is a prolongation of the rigid symmetry to a Lie algebroid morphism from the action Lie algebroid M × ? M into D ? M (or the algebraic analogue of the morphism in the case of ). The gauged sigma model results from a pullback by this morphism from the Dirac sigma model, which proves to be universal in two-spacetime dimensions in this sense.
ERIC Educational Resources Information Center
Garber, Judy; Korelitz, Katherine; Samanez-Larkin, Silvia
2012-01-01
This article highlights how the many important contributions of John R. Z. Abela's research program can inform the development and implementation of interventions for preventing depression in youth. Abela provided evidence of multiple vulnerabilities to depression including cognitive (e.g., inferential style, dysfunctional attitudes, ruminative…
RisR1478(EN) Unsteady 2D Potential-flow Forces on a
RisřR1478(EN) Unsteady 2D Potential-flow Forces on a Thin Variable Geometry Airfoil Undergoing: Unsteady 2D Potential-flow Forces on a Thin Variable Geometry Airfoil Undergoing Arbitrary Motion.): In this report analytical expressions for the unsteady 2D force distribution on a variable geometry airfoil
(-)-(2S,3R,Z)-Nakinadine A: first asymmetric synthesis and absolute configuration assignment.
Davies, Stephen G; Fletcher, Ai M; Roberts, Paul M; Shah, Rushabh S; Thompson, Amber L; Thomson, James E
2014-03-01
Mannich-type reaction of methyl phenylacetate with the N-tert-butylsulfinyl imine derived from (R)-tert-butylsulfinamide and (Z)-14-(pyridin-3'-yl)tetradec-11-enal has been used as the key step in the first asymmetric synthesis of (-)-nakinadine A. Both the 2,3-syn- and 2,3-anti-diastereoisomers were prepared; comparison of spectroscopic and specific rotation data facilitated assignment of the absolute (2S,3R,Z)-configuration within the natural product. (-)-(2S,3R,Z)-Nakinadine A was prepared in 10 steps from 11-bromoundecan-1-ol, in 10% overall yield, 97:3 dr [(Z):(E) ratio], and >98% ee. PMID:24564566
NASA Astrophysics Data System (ADS)
Jang, Hyun-Sook; Yu, Changqian; Hayes, Robert; Granick, Steve
2015-03-01
Polymer vesicles (``polymersomes'') are an intriguing class of soft materials, commonly used to encapsulate small molecules or particles. Here we reveal they can also effectively incorporate nanoparticles inside their polymer membrane, leading to novel ``2D nanocomposites.'' The embedded nanoparticles alter the capacity of the polymersomes to bend and to stretch upon external stimuli.
Symplectic Geometry Metric geometry
Wolpert, Scott A.
surfaces, metric space geometry, as well as the analytic/algebraic geometry of curvature, characteristicBasics Symplectic Geometry Curvature Metric geometry Random geodesics Weil-Petersson sampler;Basics Symplectic Geometry Curvature Metric geometry Random geodesics Table of contents 1 Introduction
Bagchi, Arjun; Mandal, Ipsita; Miwa, Akitsugu
2009-01-01
We make a detailed study of the infinite dimensional Galilean Conformal Algebra (GCA) in the case of two spacetime dimensions. Classically, this algebra is precisely obtained from a contraction of the generators of the relativistic conformal symmetry in 2d. Here we find quantum mechanical realisations of the (centrally extended) GCA by considering scaling limits of certain 2d CFTs. These parent CFTs are non-unitary and have their left and right central charges become large in magnitude and opposite in sign. We therefore develop, in parallel to the usual machinery for 2d CFT, many of the tools for the analysis of the quantum mechanical GCA. These include the representation theory based on GCA primaries, Ward identities for their correlation functions and a nonrelativistic Kac table. In particular, the null vectors of the GCA lead to differential equations for the four point function. The solution to these equations in the simplest case is explicitly obtained and checked to be consistent with various requiremen...
Diffusion Geometry Diffusion Geometry
Hirn, Matthew
Diffusion Geometry Diffusion Geometry for High Dimensional Data Matthew J. Hirn July 3, 2013 #12;Diffusion Geometry Introduction Embedding of closed curve Figure: Left: A closed, non-self-intersecting curve in 3 dimensions. Right: Its embedding as a circle. #12;Diffusion Geometry Introduction Cartoon
2D stepping drive for hyperspectral systems
NASA Astrophysics Data System (ADS)
Endrödy, Csaba; Mehner, Hannes; Grewe, Adrian; Sinzinger, Stefan; Hoffmann, Martin
2015-07-01
We present the design, fabrication and characterization of a compact 2D stepping microdrive for pinhole array positioning. The miniaturized solution enables a highly integrated compact hyperspectral imaging system. Based on the geometry of the pinhole array, an inch-worm drive with electrostatic actuators was designed resulting in a compact (1?cm2) positioning system featuring a step size of about 15?µm in a 170?µm displacement range. The high payload (20?mg) as required for the pinhole array and the compact system design exceed the known electrostatic inch-worm-based microdrives.
E. Kroupp; G. Rozenzweig; D. Osin; D. Alumot; R. D'Arcy; Y. Maron; A. Fisher; R. A. Commisso; D. Mosher; B. Weber; S. Jackson; C. Deeney
2008-01-01
Two systems were developed for measuring the time-dependent 3D density distribution of a cylindrical gas jet injected into vacuum through a triple valve-nozzle system: i) planar-laser-induced-fluorescence (PLIF), where the density distribution in either the r-z or the r-thetas planes is obtained with sub-millimeter resolution in a single measurement; ii) chordal interferometry, where Abel inversion of the data gives the radial
Vector potential remap for 2d MHD
Rambo, P W
1998-10-13
This report describes an algorithm to remap (rezone) the magnetic vector potential in 2D MHD calculations. This extends a previously described Lagrangian scheme [1] for use with ALE grids, when combined with a suitable remap capability for the hydrodynamic variables. In this scheme, the magnetic field B is a zone quantity derived from the node based vector potential A (B_{x}, B_{y}, and A_{z} in Cartesian geometry, (B_{z}, B_{r}, and A_{(small phi)} in cylindrical geometry). The scheme outlined here is closely related to a flux conserving remap of the magnetic field. Because B is derived from the updated vector potential, however, flux conservation and vanishing divergence are guaranteed; only accuracy is a concern. This is in contrast to schemes based directly on B, which require the additional constraint of preserving zero divergence [2, 3]. Beginning with Cartesian geometry, a straight forward development of the algorithm is first presented; an alternative view is then considered which makes clear the relationship to a flux conservative remapping of the zonal magnetic field. Examples comparing first and second order algorithms are shown, and the issue of energy conservation is discussed. Finally, the generalization to cylindrical geometry is given.
Interactive Geometry Remeshing
Pierre Alliez USC; Mark Meyer Caltech; Mathieu Desbrun
We present a novel technique, both flexible and efficient, for inter- active remeshing of irregular geometry. First, the original (arbitrary genus) mesh is substituted by a series of 2D maps in parameter space. Using these maps, our algorithm is then able to take advan- tage of established signal processing and halftoning tools that offer real-time interaction and intricate control. The
Interactive geometry remeshing
Pierre Alliez; Mark Meyer; Mathieu Desbrun
2002-01-01
We present a novel technique, both flexible and efficient, for interactive remeshing of irregular geometry. First, the original (arbitrary genus) mesh is substituted by a series of 2D maps in parameter space. Using these maps, our algorithm is then able to take advantage of established signal processing and halftoning tools that offer real-time interaction and intricate control. The user can
Algebraic Structures and Differential Geometry in 2D String Theory
Edward Witten; Barton Zwiebach
1992-01-01
A careful treatment of closed string BRST cohomology shows that there are\\u000amore discrete states and associated symmetries in $D=2$ string theory than has\\u000abeen recognized hitherto. The full structure, at the $SU(2)$ radius, has a\\u000anatural description in terms of abelian gauge theory on a certain three\\u000adimensional cone $Q$. We describe precisely how symmetry currents are\\u000aconstructed from
Galax2d: 2D isothermal Euler equations solver
NASA Astrophysics Data System (ADS)
Mulder, Wim
2015-03-01
Galax2d computes the 2D stationary solution of the isothermal Euler equations of gas dynamics in a rotating galaxy with a weak bar. The gravitational potential represents a weak bar and controls the flow. A damped Newton method solves the second-order upwind discretization of the equations for a steady-state solution, using a consistent linearization and a direct solver. The code can be applied as a tool for generating flow models if used on not too fine meshes, up to 256 by 256 cells for half a disk in polar coordinates.
Compatible, energy and symmetry preserving 2D Lagrangian hydrodynamics in rz-cylindrical coordinates
Shashkov, Mikhail [Los Alamos National Laboratory; Wendroff, Burton [Los Alamos National Laboratory; Burton, Donald [Los Alamos National Laboratory; Barlow, A [AWE; Hongbin, Guo [ASU
2009-01-01
We present a new discretization for 2D Lagrangian hydrodynamics in rz geometry (cylindrical coordinates) that is compatible, energy conserving and symmetry preserving. We describe discretization of the basic Lagrangian hydrodynamics equations.
2D Gaussian distributions. Equal height.
Oakes, Terry
2D Gaussian distributions. Equal height. Noise-free. Well separated. #12;2D Gaussian distributions. Equal height. Noise-free. Well separated. #12;2D Gaussian distributions. Equal height. Noise-free. Somewhat separated. #12;2D Gaussian distributions. Equal height. Noise-free. Overlapping. #12;2D Gaussian
Identifying Faces in a 2D Line Drawing Representing a Manifold Object
Jianzhuang Liu; Yong Tsui Lee; Wai-kuen Cham
2002-01-01
Abstract—A straightforward way,to illustrate a 3D model,is to use a line drawing. Faces in a 2D line drawing,provide important information for reconstructing its 3D geometry. Manifold objects belong to a class of common,solids and most solid systems,are based on manifold geometry. In this paper, a new method is proposed for finding faces from single 2D line drawings representing manifolds. The
Sevrin, A.
1993-06-01
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.
What we've learned from 3-D and r,z intense-beam simulations using the WARP code
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
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.
Batch discovery of nine z~1 clusters using x-ray and K or R,z' images
S. Andreon; I. Valtchanov; L. R. Jones; B. Altieri; M. Bremer; J. Willis; M. Pierre; H. Quintana
2005-03-10
We present results of an initial search for clusters of galaxies at z~1 and above, using data from 2.9 square degrees of XMM-Newton images. By selecting weak potentially extended X-ray sources with faint or no identifications in deep, ground-based optical imaging, we have constructed a starting sample of 19 high redshift cluster candidates. Near-IR and R,z' imaging of these fields identified nine of them as high redshift systems. Six of these were confirmed spectroscopically, three at z~1.0 and the other three in 0.8~1 clusters, after discarding "low" redshift systems at z ~2.5 10^{-15} ergs/cm2/s ([0.5-2] keV) and this is a lower limit, having screened not all potential z~1 candidate clusters. Coordinates, x-ray measures and evidence for nine x-ray selected high redshift clusters is given.
NASA Astrophysics Data System (ADS)
Valdez, F. Roberto Fragoso; Alvarez Romero, J. Trinidad
2001-10-01
The functions ?(r, z), G(r, ?), g(r) and F(r, ?) were calculated for Amersham model CDCS-M-type 137Cs source by means of Monte Carlo simulation using the algorithm PENELOPE. These functions are required to verify and/or to feed planning systems or directly as entrance data for the manual planning of the distribution of absorbed dose according with the recommendations of the TG 43, [1]. The values of the constant ? (r, Z) were determined as the quotient of absorbed dose rate distribution in water and air kerma strength in "free air" Sk. The values obtained for ? (r, Z) differ up to 3% of those reported in the literature [2], being very sensitive to the cutoff energy for the electrons in the interface of the source's encapsulated and water.
Pythagoras' Theorem on a 2D-Lattice from a \\
Jian Dai; Xing-Chang Song
2001-01-01
One of the key ingredients of A. Connes' noncommutative geometry is a\\u000ageneralized Dirac operator which induces a metric(Connes' distance) on the\\u000astate space. We generalize such a Dirac operator devised by A. Dimakis et al,\\u000awhose Connes' distance recovers the linear distance on a 1D lattice, into 2D\\u000alattice. This Dirac operator being \\
Edwin Langmann
2010-04-14
A detailed derivation of a two dimensional (2D) low energy effective model for spinless fermions on a square lattice with local interactions is given. This derivation utilizes a particular continuum limit that is justified by physical arguments. It is shown that the effective model thus obtained can be treated by exact bosonization methods. It is also discussed how this effective model can be used to obtain physical information about the corresponding lattice fermion system.
Conformal Geometry and the Universe By Anthony Lasenby
Cambridge, University of
of the transfer of a result from 2d non-Euclidean geometry to 4d de Sitter space (the Origin Lemma in the Poincar histories. Keywords: conformal geometry, geometric algebra, non-Euclidean geometry, de Sitter space to the case of non-Euclidean geometries, both spherical and hyperbolic, and in Lasenby & Lasenby (2003) have
Subtracted geometry from Harrison transformations
NASA Astrophysics Data System (ADS)
Virmani, Amitabh
2012-07-01
We consider the rotating non-extremal black hole of N=2 D=4 STU supergravity carrying three magnetic charges and one electric charge. We show that its subtracted geometry is obtained by applying a specific SO(4,4) Harrison transformation on the black hole. As previously noted, the resulting subtracted geometry is a solution of the N=2 S=T=U supergravity.
Nanoimprint lithography: 2D or not 2D? A review
NASA Astrophysics Data System (ADS)
Schift, Helmut
2015-04-01
Nanoimprint lithography (NIL) is more than a planar high-end technology for the patterning of wafer-like substrates. It is essentially a 3D process, because it replicates various stamp topographies by 3D displacement of material and takes advantage of the bending of stamps while the mold cavities are filled. But at the same time, it keeps all assets of a 2D technique being able to pattern thin masking layers like in photon- and electron-based traditional lithography. This review reports about 20 years of development of replication techniques at Paul Scherrer Institut, with a focus on 3D aspects of molding, which enable NIL to stay 2D, but at the same time enable 3D applications which are "more than Moore." As an example, the manufacturing of a demonstrator for backlighting applications based on thermally activated selective topography equilibration will be presented. This technique allows generating almost arbitrary sloped, convex and concave profiles in the same polymer film with dimensions in micro- and nanometer scale.
Andrey V. Koshelkin; Cheuk-Yin Wong
2012-07-27
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] [Moscow Institute for Physics and Engineering, Russia; Wong, Cheuk-Yin [ORNL] [ORNL
2012-01-01
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.
in matematica, fisica e filosofia V e n e r d i 2 6 M a r z o 2 0 0 4
Di Nasso, Mauro
LŐinfinito in matematica, fisica e filosofia V e n e r d i 2 6 M a r z o 2 0 0 4 curatori: Vieri, Universitŕ di Pisa Lucio Russo Dip. Matematica dell'Universitŕ di Roma II Steven Shore Dip. Fisica Carlo Toffalori Dip. Matematica e Fisica, Universitŕ di Camerino Vieri Benci Dip. Matematica Applicata
Persistence Measures for 2d Soap Froth
NASA Astrophysics Data System (ADS)
Feng, Y.; Ruskin, H. J.; Zhu, B.
Soap froths as typical disordered cellular structures, exhibiting spatial and temporal evolution, have been studied through their distributions and topological properties. Recently, persistence measures, which permit representation of the froth as a two-phase system, have been introduced to study froth dynamics at different length scales. Several aspects of the dynamics may be considered and cluster persistence has been observed through froth experiment. Using a direct simulation method, we have investigated persistent properties in 2D froth both by monitoring the persistence of survivor cells, a topologically independent measure, and in terms of cluster persistence. It appears that the area fraction behavior for both survivor and cluster persistence is similar for Voronoi froth and uniform froth (with defects). Survivor and cluster persistent fractions are also similar for a uniform froth, particularly when geometries are constrained, but differences observed for the Voronoi case appear to be attributable to the strong topological dependency inherent in cluster persistence. Survivor persistence, on the other hand, depends on the number rather than size and position of remaining bubbles and does not exhibit the characteristic decay to zero.
Pedro V. Sander; Zoë J. Wood; Steven J. Gortler; John Snyder; Hugues Hoppe
2003-01-01
We introduce multi-chart geometry images, a new representation for arbitrary surfaces. It is created by resampling a surface onto a regular 2D grid. Whereas the original scheme of Gu et al. maps the entire surface onto a single square, we use an atlas construction to map the surface piecewise onto charts of arbitrary shape. We demonstrate that this added flexibility
Georgi, Howard; Kats, Yevgeny [Center for the Fundamental Laws of Nature, Jefferson Physical Laboratory, Harvard University, Cambridge, Massachusetts 02138 (United States)
2008-09-26
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 scale-invariant theory with nontrivial anomalous dimensions at low energies. We construct a toy standard model coupling to the fermions in the Sommerfield model and study how the transition from unparticle behavior at low energies to free particle behavior at high energies manifests itself in interactions with the toy standard model particles.
2D quasiperiodic plasmonic crystals.
Bauer, Christina; Kobiela, Georg; Giessen, Harald
2012-01-01
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
Ultrafast 2D IR Vibrational Echo Spectroscopy
Fayer, Michael D.
Ultrafast 2D IR Vibrational Echo Spectroscopy JUNRONG ZHENG, KYUNGWON KWAK, AND M. D. FAYER The experimental technique and applications of ultrafast two- dimensional infrared (2D IR) vibrational echo systems. The form and time evolution of the 2D IR spectrum permits examination of processes that cannot
2-D axisymmetric line transport
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
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.
Fast 2D non-LTE radiative modelling of prominences I. Numerical methods and benchmark results
L. Leger; L. Chevallier; F. Paletou
2007-03-27
New high-resolution spectropolarimetric observations of solar prominences require improved radiative modelling capabilities in order to take into account both multi-dimensional - at least 2D - geometry and complex atomic models. This makes necessary the use of very fast numerical schemes for the resolution of 2D non-LTE radiative transfer problems considering freestanding and illuminated slabs. The implementation of Gauss-Seidel and successive over-relaxation iterative schemes in 2D, together with a multi-grid algorithm, is thoroughly described in the frame of the short characteristics method for the computation of the formal solution of the radiative transfer equation in cartesian geometry. We propose a new test for multidimensional radiative transfer codes and we also provide original benchmark results for simple 2D multilevel atom cases which should be helpful for the further development of such radiative transfer codes, in general.
NKG2D ligands as therapeutic targets
Spear, Paul; Wu, Ming-Ru; Sentman, Marie-Louise; Sentman, Charles L.
2013-01-01
The Natural Killer Group 2D (NKG2D) receptor plays an important role in protecting the host from infections and cancer. By recognizing ligands induced on infected or tumor cells, NKG2D modulates lymphocyte activation and promotes immunity to eliminate ligand-expressing cells. Because these ligands are not widely expressed on healthy adult tissue, NKG2D ligands may present a useful target for immunotherapeutic approaches in cancer. Novel therapies targeting NKG2D ligands for the treatment of cancer have shown preclinical success and are poised to enter into clinical trials. In this review, the NKG2D receptor and its ligands are discussed in the context of cancer, infection, and autoimmunity. In addition, therapies targeting NKG2D ligands in cancer are also reviewed. PMID:23833565
2-D and 3-D computations of curved accelerator magnets
Turner, L.R.
1991-01-01
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.
Predicting 2D Target Velocity Cannot Help 2D Motion Integration for Smooth Pursuit Initiation
Carrasco, Marisa
Report Predicting 2D Target Velocity Cannot Help 2D Motion Integration for Smooth Pursuit August 2006 Montagnini, Anna, Miriam Spering, and Guillaume S. Masson. Predicting 2D target velocity cannot help 2D motion integration for smooth pursuit initiation. J Neurophysiol 96: 35453550, 2006
Breaking of Rotational Symmetry in Cylindrically Bounded 2D Electron Plasmas and 2D Fluids
Marcus, Philip S.
Breaking of Rotational Symmetry in Cylindrically Bounded 2D Electron Plasmas and 2D Fluids Eli 24 April 2003; published 17 November 2004) Off-axis final states of cylindrically bounded 2D fluids can develop from initially unstable, but cylindrically symmetric, 2D vorticity distributions
Eldar, Yonina
COMPRESSED 3D ULTRASOUND IMAGING WITH 2D ARRAYS Michael Birk*, Amir Burshtein*, Tanya Chernyakova's Nyquist rate, which greatly increases the volume of data that must be processed. In 3D ultrasound imaging extend previous work on frequency domain beamforming for 2D ultrasound imaging to the geometry imposed
GEOMETRY EDUCATION FOR DEVELOPING SPATIAL VISUALISATION ABILITIES OF ENGINEERING STUDENTS
Cornelie LEOPOLD
The importance of descriptive geometry was pushed back in the last years in many curricula of engineering studies. Geometry Education was often substituted by training of CAD-systems and represen- tation techniques. This development leads to a deficiency in spatial visualisation abilities of engineering students. Descriptive Geometry provides the foundations for creating and understanding 2-D drawings of 3-D objects and helps
D. Sevic
1999-01-01
A a new implementation of the two-dimensional FFT (2-D FFT) is proposed. Compared with the usual separable solution, the new realization of the 2-D FFT has reduced arithmetic complexity. Computational savings are achieved because the 2-D case enables, after some modifications of the basic separable algorithm, scaling and inverse scaling of butterfly operators. The new improvement is also applied to
Iconic Indexing by 2-D Strings
Shi-Kuo Chang; Qing-Yun Shi; Cheng-Wen Yan
1987-01-01
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
NSDL National Science Digital Library
2010-01-01
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.
Michael Deering
1995-01-01
This paper introduces the concept of Geometry Compression, al- lowing 3D triangle data to be represented with a factor of 6 to 10 times fewer bits than conventional techniques, with only slight loss- es in object quality. The technique is amenable to rapid decompres- sion in both software and hardware implementations; if 3D render- ing hardware contains a geometry decompression
NSDL National Science Digital Library
Ms. Hocutt
2010-02-03
Play these fun games to see how good your geometry skills are and learn more about geometry. First, let's see if you can Feed Billy Bug. Then, see if you can help in the Space Rescue. If you're ready, play this fun game about angles find out what is your angle ?. ...
Lott, Geoffrey A; Utterback, James K; Widom, Julia R; Aspuru-Guzik, Alán; Marcus, Andrew H
2011-01-01
By applying a phase-modulation fluorescence approach to 2D electronic spectroscopy, we studied the conformation-dependent exciton-coupling of a porphyrin dimer embedded in a phospholipid bilayer membrane. Our measurements specify the relative angle and separation between interacting electronic transition dipole moments, and thus provide a detailed characterization of dimer conformation. Phase-modulation 2D fluorescence spectroscopy (PM-2D FS) produces 2D spectra with distinct optical features, similar to those obtained using 2D photon-echo spectroscopy (2D PE). Specifically, we studied magnesium meso tetraphenylporphyrin dimers, which form in the amphiphilic regions of 1,2-distearoyl-sn-glycero-3-phosphocholine liposomes. Comparison between experimental and simulated spectra show that while a wide range of dimer conformations can be inferred by either the linear absorption spectrum or the 2D spectrum alone, consideration of both types of spectra constrains the possible structures to a "T-shaped" geometry. The...
Electromagnetic gauge for measuring the radial particle velocity in 2-D flow
NASA Astrophysics Data System (ADS)
Rosenberg, G.; Yaziv, D.; Mayseless, M.
1982-04-01
Applications of existing EMV gauges are limited for uniaxial strain configurtions, since the gauge length must remain fixed during the motion. A modification of the electromagnetic technique which provides measurements in 2-D flow is presented. When the problem of a projectile impacting a target is described in cylindrical coordinates (r,z) with z as axis of symmetry, the flow can be defined by the particle velocity components Uz,Ur. A new gauge is made of a thin copper wire having a circular turn shape. The gauge is embedded in the target material in a plane normal to the z axis axisymetrically. Magnetic field is generated by a solenoid wrapped around the target so that the field lines are parallel to the z axis. In a configuration like this, only the radial motion contributes to the EMF, therefore in a uniform filed, B, the measured EMF depends on the radial particle velocity: E=2?Br(t)Ur(t), where the circular turn radius, r(t), is obtained by integrating the velocity Ur(t). This new method hjas been demonstrted by experiment, impacting a rod shaped projectile made of PMMA into a target of the same material. Results are compared with 2-D calculation.
1-D & 2-D Scans Epistasis Plots
Yandell, Brian S.
Outline Overview 1-D & 2-D Scans Anova Fit Epistasis Plots Conclusion Prototype QTL Strategy-D Scans Anova Fit Epistasis Plots Conclusion Overview Initialization 1-D & 2-D Scans Anova Fit Epistasis Plots Conclusion Brian S. Yandell, W. Whipple Neely, Nengjun Yi Prototype QTL Strategy: Phenotype
Annotated Bibliography of EDGE2D Use
J.D. Strachan and G. Corrigan
2005-06-24
This annotated bibliography is intended to help EDGE2D users, and particularly new users, find existing published literature that has used EDGE2D. Our idea is that a person can find existing studies which may relate to his intended use, as well as gain ideas about other possible applications by scanning the attached tables.
Design Application Translates 2-D Graphics to 3-D Surfaces
NASA Technical Reports Server (NTRS)
2007-01-01
Fabric Images Inc., specializing in the printing and manufacturing of fabric tension architecture for the retail, museum, and exhibit/tradeshow communities, designed software to translate 2-D graphics for 3-D surfaces prior to print production. Fabric Images' fabric-flattening design process models a 3-D surface based on computer-aided design (CAD) specifications. The surface geometry of the model is used to form a 2-D template, similar to a flattening process developed by NASA's Glenn Research Center. This template or pattern is then applied in the development of a 2-D graphic layout. Benefits of this process include 11.5 percent time savings per project, less material wasted, and the ability to improve upon graphic techniques and offer new design services. Partners include Exhibitgroup/Giltspur (end-user client: TAC Air, a division of Truman Arnold Companies Inc.), Jack Morton Worldwide (end-user client: Nickelodeon), as well as 3D Exhibits Inc., and MG Design Associates Corp.
2D and 3D Method of Characteristic Tools for Complex Nozzle Development
NASA Technical Reports Server (NTRS)
Rice, Tharen
2003-01-01
This report details the development of a 2D and 3D Method of Characteristic (MOC) tool for the design of complex nozzle geometries. These tools are GUI driven and can be run on most Windows-based platforms. The report provides a user's manual for these tools as well as explains the mathematical algorithms used in the MOC solutions.
Parallel algorithms for 2-D cylindrical transport equations of Eigenvalue problem
Wei, J.; Yang, S. [Institute of Applied Physics and Computational Mathematics, No. 2, Fenhao Donglu, Haidian District, Beijng (China)
2013-07-01
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)
Algebra = Geometry Sandor Kovacs
Kovács, Sándor
Algebra = Geometry S´andor Kov´acs University of Washington #12;Motto "To me, algebraic geometry is algebra with a kick" Solomon Lefschetz #12;Geometry Geometry = Space + Functions #12;Geometry Geometry = Space + Functions Type of function Type of Geometry #12;Geometry Geometry = Space + Functions Type
Lajos Tamássy
\\u000a In the thirties of the 19th century János Bolyai and Nikolai Ivanovi? Lobacevskii created the hyperbolic geometry. Thus they proved that not only the\\u000a Euclidean but also other geometries may exist. Concerning its geometrical importance, this discovery can be compared to the\\u000a change which replaced the Ptolemaic geocentric concept of astronomy by the heliocentric point of view of Copernicus. Hyperbolic
Partially gapped fermions in 2D
Jonas de Woul; Edwin Langmann
2010-04-16
We compute mean field phase diagrams of two closely related interacting fermion models in two spatial dimensions (2D). The first is the so-called 2D t-t'-V model describing spinless fermions on a square lattice with local hopping and density-density interactions. The second is the so-called 2D Luttinger model that provides an effective description of the 2D t-t'-V model and in which parts of the fermion degrees of freedom are treated exactly by bosonization. In mean field theory, both models have a charge-density-wave (CDW) instability making them gapped at half-filling. The 2D t-t'-V model has a significant parameter regime away from half-filling where neither the CDW nor the normal state are thermodynamically stable. We show that the 2D Luttinger model allows to obtain more detailed information about this mixed region. In particular, we find in the 2D Luttinger model a partially gapped phase that, as we argue, can be described by an exactly solvable model.
2D non-LTE radiative modelling of He I spectral lines formed in solar prominences
L. Leger; F. Paletou
2008-11-28
The diagnosis of new high-resolution spectropolarimetric observations of solar prominences made in the visible and near-infrared mainly, requires a radiative modelling taking into account for both multi-dimensional geometry and complex atomic models. Hereafter we contribute to the improvement of the diagnosis based on the observation of He I multiplets, by considering 2D non-LTE unpolarized radiation transfer, and taking also into account the atomic fine structure of helium. It is an improvement and a direct application of the multi-grid Gauss-Seidel/SOR iterative scheme in 2D cartesian geometry developed by us. It allows us to compute realistic emergent intensity profiles for the He I 10830 A and D3 multiplets, which can be directly compared to the simultaneous and high-resolution observations made at THeMIS. A preliminary 2D multi-thread modelling is also discussed.
Quenching of N( 2D) by cyanogen
NASA Astrophysics Data System (ADS)
Black, G.; Jusinski, L. E.; Slanger, T. G.
1987-10-01
A flowing afterglow in a 1% N 2/Ar mixture at 10 Torr has been used as a source of N( 2D), and resonance-enhanced multiphoton ionization (REMPI) at 269 nm has been used to follow the removal of the N( 2D) by C 2N 2 and O 2. The rate of removal by O 2 is consistent with previous work. The rate coefficient for N( 2D)/C 2N 2 interaction has been measured as (1.5±0.2) × 10 -11 cm 3 molecule -1 s -1 at 300 K, although the products have not yet been determined.
2D materials: to graphene and beyond
NASA Astrophysics Data System (ADS)
Mas-Ballesté, Rubén; Gómez-Navarro, Cristina; Gómez-Herrero, Julio; Zamora, Félix
2011-01-01
This review is an attempt to illustrate the different alternatives in the field of 2D materials. Graphene seems to be just the tip of the iceberg and we show how the discovery of alternative 2D materials is starting to show the rest of this iceberg. The review comprises the current state-of-the-art of the vast literature in concepts and methods already known for isolation and characterization of graphene, and rationalizes the quite disperse literature in other 2D materials such as metal oxides, hydroxides and chalcogenides, and metal-organic frameworks.
Brittle damage models in DYNA2D
Faux, D.R.
1997-09-01
DYNA2D is an explicit Lagrangian finite element code used to model dynamic events where stress wave interactions influence the overall response of the system. DYNA2D is often used to model penetration problems involving ductile-to-ductile impacts; however, with the advent of the use of ceramics in the armor-anti-armor community and the need to model damage to laser optics components, good brittle damage models are now needed in DYNA2D. This report will detail the implementation of four brittle damage models in DYNA2D, three scalar damage models and one tensor damage model. These new brittle damage models are then used to predict experimental results from three distinctly different glass damage problems.
Beltrami States in 2D Electron Magnetohydrodynamics
Shivamoggi, B K
2015-01-01
In this paper, the Hamiltonian formulations along with the Poisson brackets for two-dimensional (2D) electron magnetohydrodynamics (EMHD) flows are developed. These formulations are used to deduce the Beltrami states for 2D EMHD flows. In the massless electron limit, the EMHD Beltrami states reduce to the force-free states, though there is no force-free Beltrami state in the general EMHD case.
Ianir A. Ideses; Leonid P. Yaroslavsky; Barak Fishbain; Roni Vistuch
2007-01-01
In this paper, we present an efficient method to synthesize 3D video from compressed 2D video. The 2D video is analyzed by computing frame-by-frame motion maps. For this computation, MPEG motion vectors extraction was performed. Using the extracted motion vector maps, the video undergoes analysis and the frames are segmented to provide object-wise depth ordering. The frames are then used
Ianir A. Ideses; Leonid P. Yaroslavsky
2006-01-01
In this paper, we present methods to synthesize 3D video from arbitrary 2D video. The 2D video is analyzed by computing frame-by-frame motion maps. For this computation, several methods were tested, including optical flow, segmentation and correlation based target location. Using the computed motion maps, the video undergoes analysis and the frames are segmented to provide object-wise depth ordering. The
Wave Propagation in 1-D Spiral geometry
Chatterjee, Deep
2014-01-01
In this article, we investigate the wave equation in spiral geometry and study the modes of vibrations of a one-dimensional (1-D) string in spiral shape. Here we show that the problem of wave propagation along a spiral can be reduced to Bessel differential equation and hence, very closely related to the problem of radial waves of two-dimensional (2-D) vibrating membrane in circular geometry.
NSDL National Science Digital Library
Rusin, David J., 1957-
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.
2D Radiation MHD K-shell Modeling of Single Wire Array Stainless Steel Experiments on the Z Machine
Thornhill, J. W.; Giuliani, J. L.; Apruzese, J. P.; Chong, Y. K.; Davis, J.; Dasgupta, A. [Plasma Physics Division, Naval Research Laboratory, Washington DC 20375 (United States); Whitney, K. G.; Clark, R. W. [Berkeley Research Associates, Beltsville Maryland 20705 (United States); Jones, B.; Coverdale, C. A.; Ampleford, D. J.; Cuneo, M. E. [Sandia National Laboratories, Albuquerque NM 87545 (United States); Deeney, C. [National Nuclear Security Administration, Washington DC 20585 (United States)
2009-01-21
Many physical effects can produce unstable plasma behavior that affect K-shell emission from arrays. Such effects include: asymmetry in the initial density profile, asymmetry in power flow, thermal conduction at the boundaries, and non-uniform wire ablation. Here we consider how asymmetry in the radiation field also contributes to the generation of multidimensional plasma behavior that affects K-shell power and yield. To model this radiation asymmetry, we have incorporated into the MACH2 r-z MHD code a self-consistent calculation of the non-LTE population kinetics based on radiation transport using multi-dimensional ray tracing. Such methodology is necessary for modeling the enhanced radiative cooling that occurs at the anode and cathode ends of the pinch during the run-in phase of the implosion. This enhanced radiative cooling is due to reduced optical depth at these locations producing an asymmetric flow of radiative energy that leads to substantial disruption of large initial diameter (>5 cm) pinches and drives 1D into 2D fluid (i.e., Rayleigh-Taylor like) flows. The impact of this 2D behavior on K-shell power and yield is investigated by comparing 1D and 2D model results with data obtained from a series of single wire array stainless steel experiments performed on the Z generator.
Grid generation for general 2-D regions using hyperbolic equations
NASA Technical Reports Server (NTRS)
Cordova, Jeffrey Q.; Barth, Timothy J.
1988-01-01
A method for applying a hyperbolic grid generation scheme to the construction of meshes in general 2-D regions has been developed. This approach, which follows the theory developed by Steger and Chaussee (1980) and the algorithm outlined by Kinsey and Barth (1984), is based on improving local grid control. This is accomplished by adding an angle control source term to the equations and using a new algorithm for computing the volume source term. These modifications lead to superior methods for fixing the 'local' problems of hyperbolic grid generation, namely, propagation of initial discontinuities and formation of grid shocks (crossing grid lines). More importantly, a method for solving the global problem of constraining the grid with more than one boundary (internal grid generation) has been developed. These algorithms have been implemented in an interactive grid generation program and the results for several geometries are presented and discussed.
Interpretive 2-D treatment of scrape-off-layer plasmas
Umansky, M.; Allen, A.; Daughton, W. [MIT Plasma Fusion Center, Cambridge, MA (United States)] [and others
1996-12-31
The width of the scrape-off-layer in a tokamak is determined by cross field transport. In Alcator C-mod the plasma parameters in the scrape-off-layer are measured at upstream and divertor plate locations. We solve a 2-D scrape-off-layer heat conduction equation in the flux geometry (as determined by EFIT) of the C-mod experiment. Bolometric measurements are utilized for the radiative loss term. We use the end wall probe measurements of electron temperature as a boundary condition and the fast scanning probe measurements of upstream temperature are treated as constraints to determine the cross field transport and thermal conductivity. Results are compared with 1-D onion-skin-model predictions.
Novel antenna coupled 2D plasmonic terahertz detection.
Allen, Jim (UC Santa Barbara); Dyer, Greg (UC Santa Barbara); Reno, John Louis; Shaner, Eric Arthur
2010-03-01
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}.
Wu, C.H.; Li, C.; Young, F.F. [Auburn Univ., AL (United States). Dept. of Electrical Engineering] [Auburn Univ., AL (United States). Dept. of Electrical Engineering; Tsai, J.H. [National High-Performance Computing Center, Hsinchu (Taiwan, Province of China)] [National High-Performance Computing Center, Hsinchu (Taiwan, Province of China)
1995-08-01
A new kinetic scheme, the generalized Monte Carlo flux (GMCF) method, provides the electron particle distribution function in phase space, f(v, {mu}, r, z, t) (v: speed, {mu}: velocity angle, r: radial position, z: axial position, and t: time), for solving the Boltzmann equation in modeling capacitively coupled RF discharges. For a simulation with spatial- and temporal-varying fields in RF discharges, the GMCF method handles the collision terms of the Boltzmann equation by using one transition matrix to compute the collision transition between velocity space cells. An anti-diffusion flux transport scheme is developed to overcome the numerical diffusion in the velocity and configuration spaces. The major advantages of the GMCF method are the increase in resolution in the tail of distribution functions and the decrease of computation time. The GMCF calculation results in terms of microscopic electron distribution function and macroscopic quantities of density, electric field and ionization rate, are presented for RF discharges and compared with other kinetic and fluid simulation and experimental results. The effects of the induced radial electric field in the sheath close to the radial wall in a cylindrically symmetric parallel-plate geometry are discussed.
MAZE: an input generator for DYNA2D and NIKE2D
Hallquist, J.O.
1981-04-01
MAZE is a new interactive program that is being developed as an input generator for DYNA2D and NIKE2D; however, the generated mesh file is compatible with other finite element programs as well. The purpose of this report is to provide a preliminary user's manual. Since the development is not yet complete, users are invited and encouraged to make suggestions concerning any options of features that they would like added. Eventually, MAZE may become part of the DYNA2D and NIKE2D programs.
2D Models for Dust-driven AGB Star Winds
Peter Woitke
2006-02-16
New axisymmetric (2D) models for dust-driven winds of C-stars are presented which include hydrodynamics with radiation pressure on dust, equilibrium chemistry and time-dependent dust formation with coupled grey Monte Carlo radiative transfer. Considering the most simple case without stellar pulsation (hydrostatic inner boundary condition) these models reveal a more complex picture of the dust formation and wind acceleration as compared to earlier published spherically symmetric (1D) models. The so-called exterior $\\kappa$-mechanism causes radial oscillations with short phases of active dust formation between longer phases without appreciable dust formation, just like in the 1D models. However, in 2D geometry, the oscillations can be out-of-phase at different places above the stellar atmosphere which result in the formation of dust arcs or smaller caps that only occupy a certain fraction of the total solid angle. These dust structures are accelerated outward by radiation pressure, expanding radially and tangentially like mushroom clouds, while dust-poor matter is falling back towards the star at other places. A highly dynamical and turbulent dust formation zone is created in this way, which again leads to inhomogeneous dust production. Further away from the star, flow instabilities (e.g. Rayleigh-Taylor) have time to fragment the outward moving arcs and shells to produce numerous small-scale cloud-like sub-structures.
Modelling RF sources using 2-D PIC codes
Eppley, K.R.
1993-03-01
In recent years, many types of RF sources have been successfully modelled using 2-D PIC codes. Both cross field devices (magnetrons, cross field amplifiers, etc.) and pencil beam devices (klystrons, gyrotrons, TWT'S, lasertrons, etc.) have been simulated. All these devices involve the interaction of an electron beam with an RF circuit. For many applications, the RF structure may be approximated by an equivalent circuit, which appears in the simulation as a boundary condition on the electric field ( port approximation''). The drive term for the circuit is calculated from the energy transfer between beam and field in the drift space. For some applications it may be necessary to model the actual geometry of the structure, although this is more expensive. One problem not entirely solved is how to accurately model in 2-D the coupling to an external waveguide. Frequently this is approximated by a radial transmission line, but this sometimes yields incorrect results. We also discuss issues in modelling the cathode and injecting the beam into the PIC simulation.
Modelling RF sources using 2-D PIC codes
Eppley, K.R.
1993-03-01
In recent years, many types of RF sources have been successfully modelled using 2-D PIC codes. Both cross field devices (magnetrons, cross field amplifiers, etc.) and pencil beam devices (klystrons, gyrotrons, TWT`S, lasertrons, etc.) have been simulated. All these devices involve the interaction of an electron beam with an RF circuit. For many applications, the RF structure may be approximated by an equivalent circuit, which appears in the simulation as a boundary condition on the electric field (``port approximation``). The drive term for the circuit is calculated from the energy transfer between beam and field in the drift space. For some applications it may be necessary to model the actual geometry of the structure, although this is more expensive. One problem not entirely solved is how to accurately model in 2-D the coupling to an external waveguide. Frequently this is approximated by a radial transmission line, but this sometimes yields incorrect results. We also discuss issues in modelling the cathode and injecting the beam into the PIC simulation.
Calibration of 2D unstructured grid methods on propulsive flowfields
NASA Astrophysics Data System (ADS)
Karman, Steve L., Jr.; Spragle, Gregory S.
1992-09-01
A computational fluid dynamics (CFD) method is presented for the analysis of complex two-dimensional (2D) geometries using unstructured grid techniques. The grid generation procedure uses a split tree technique for subdividing the domain and generating internal mesh points. A Delaunay triangulation method is employed to triangulate the points, then iteratively refines the mesh based on cell aspect ratios and area variation to improve the quality of the initial mesh. The full Navier-Stokes equations are solved using an upwind flux difference splitting scheme for the inviscid flux and a central differencing scheme for the viscous flux. A two equation turbulence model is included for analyzing turbulent flows. A Jacobi iteration procedure is used to solve the linear set of implicit equations at each time step. Two 2D propulsive flowfields are analyzed and compared with experimental data. The grids are adapted to the flowfield by refinement based on the flowfield gradients. Improved resolution of the pertinent flowfield features were a result of the grid adaption employed.
2D microwave imaging reflectometer electronics
Spear, A. G.; Domier, C. W., E-mail: cwdomier@ucdavis.edu; Hu, X.; Muscatello, C. M.; Ren, X.; Luhmann, N. C. [Electrical and Computer Engineering, University of California, Davis, California 95616 (United States); Tobias, B. J. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)
2014-11-15
A 2D microwave imaging reflectometer system has been developed to visualize electron density fluctuations on the DIII-D tokamak. Simultaneously illuminated at four probe frequencies, large aperture optics image reflections from four density-dependent cutoff surfaces in the plasma over an extended region of the DIII-D plasma. Localized density fluctuations in the vicinity of the plasma cutoff surfaces modulate the plasma reflections, yielding a 2D image of electron density fluctuations. Details are presented of the receiver down conversion electronics that generate the in-phase (I) and quadrature (Q) reflectometer signals from which 2D density fluctuation data are obtained. Also presented are details on the control system and backplane used to manage the electronics as well as an introduction to the computer based control program.
Extended 2d generalized dilaton gravity theories
R. O. de Mello
2008-08-06
We show that an anomaly-free description of matter in (1+1) dimensions requires a deformation of the 2d relativity principle, which introduces a non-trivial center in the 2d Poincare algebra. Then we work out the reduced phase-space of the anomaly-free 2d relativistic particle, in order to show that it lives in a noncommutative 2d Minkowski space. Moreover, we build a Gaussian wave packet to show that a Planck length is well-defined in two dimensions. In order to provide a gravitational interpretation for this noncommutativity, we propose to extend the usual 2d generalized dilaton gravity models by a specific Maxwell component, which gauges the extra symmetry associated with the center of the 2d Poincare algebra. In addition, we show that this extension is a high energy correction to the unextended dilaton theories that can affect the topology of space-time. Further, we couple a test particle to the general extended dilaton models with the purpose of showing that they predict a noncommutativity in curved space-time, which is locally described by a Moyal star product in the low energy limit. We also conjecture a probable generalization of this result, which provides a strong evidence that the noncommutativity is described by a certain star product which is not of the Moyal type at high energies. Finally, we prove that the extended dilaton theories can be formulated as Poisson-Sigma models based on a nonlinear deformation of the extended Poincare algebra.
2D Surface Trap for Quantum Simulation
NASA Astrophysics Data System (ADS)
Gillen, Jonathon; Bakr, Waseem; Peng, Amy; Fölling, Simon; Greiner, Markus
2009-05-01
We present a novel optical trapping scheme for low dimensional quantum gases. Using a combination of evanescent waves, standing waves, and magnetic potentials we create a 2D Bose-Einstein condensate at a distance of only a few microns away from a glass surface. The trapping potentials near the surface are smooth and allow for a highly anisotropic confinement with an aspect ratio of 300:1:1 as well as long lifetimes of the 2D quantum gas. We are able to directly detect phase fluctuations and vortices. The setup is especially suitable for many body quantum simulations and applications such as high precision measurements close to surfaces.
Harmonic generation in 2D layered materials
NASA Astrophysics Data System (ADS)
Janisch, Corey; Ma, Ding; Mehta, Nikhil; Laura-Elias, Ana; Perea-Lopez, Nestor; Terrones, Mauricio; Liu, Zhiwen
2014-09-01
Two-Dimensional (2D) layered materials have garnered interest due to their novel optical and electronic properties. In this work, we investigate Second Harmonic Generation (SHG) in Tungsten Disulfide (WS2) monolayers grown on SiO2/Si substrates and suspended on a transmission electron microscopy grid; we find an unusually large second order susceptibility, which is nearly three orders of magnitude larger than common nonlinear crystals. We have also developed a Green's function based formalism to model the harmonic generation from a 2D layer .
841 P.2d 990 Page 1 4 Cal.4th 389, 841 P.2d 990, 14 Cal.Rptr.2d 470
Kammen, Daniel M.
841 P.2d 990 Page 1 4 Cal.4th 389, 841 P.2d 990, 14 Cal.Rptr.2d 470 (Cite as: 4 Cal.4th 389, 841 P.2d 990) BOALT STUDENTS PLEASE READ PAGES 5-6 (*394-97 STARTING WITH: II. The Constitutional. Works. #12;841 P.2d 990 Page 2 4 Cal.4th 389, 841 P.2d 990, 14 Cal.Rptr.2d 470 (Cite as: 4 Cal.4th 389
Dipolar Quasi-2D Bosons with Non-zero Dipole Tilt Angle
NASA Astrophysics Data System (ADS)
Shen, Pengtao; Quader, Khandker
2015-03-01
We study properties of dipolar bosons in quasi-2D geometry, with dipoles oriented at an angle to the direction perpendicular to the confining 2D plane. Starting from time-dependent Gross-Pitaevski equations, and the resulting Bogoliubov-de Gennes equations, we calculate the excitation spectrum of the Bose-Einstein condensate, and explore possible instabilities of the system as the tilt angle, system density and the relative strength of the dipole-dipole interaction are varied. We study how the depletion of the condensate varies with respect to these parameters. We also explore the effect of the anisotropic dipolar interaction on results in different momentum directions.
Si-based 1D and 2D slot waveguides for magneto-optics
NASA Astrophysics Data System (ADS)
Khanna, Amit; Säynätjoki, Antti; Tervonen, Ari; Honkanen, Seppo
2011-03-01
Although the new polymer based nano-composite materials that have been proposed for magneto-optic applications provide a high Verdet constant, they also exhibit high losses. These materials present a different challenge for realizing efficient integrated magneto-optic devices compared to traditionally used materials such as garnets. In this paper we study the figure of merit of 1D and 2D slot waveguide geometries and compare their advantages. In 2D slot waveguides the non-reciprocal TE/TM mode conversion, and in asymmetric 1D slot waveguides the non-reciprocal phase shift, respectively, are analyzed.
2D and 3D meso-scale finite element models for ravelling analysis of porous asphalt concrete
L. T. Mo; M. Huurman; S. P. Wu; A. A. A. Molenaar
2008-01-01
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
NSDL National Science Digital Library
Ms. Yost
2009-10-26
Let's practice some geometry skills. First, try to feed Billy Bug all the grubs in Billy Bug: Quadrant I. Just click on "Start," move Billy Bug with the arrow keys on the screen, and click "Feed" when you're at the coordinate where the grub is located. If you're up for a challenge, try Billy Bug: All Quadrants! Then, in Robo Packer, you will ...
A comprehensive 2-D divertor data set from DIII-D for edge theory validation
Fenstermacher, M.E.; Allen, S.L.; Hill, D.N. [and others
1996-02-01
A comprehensive set of experiments has been carried out on the DIII-D tokamak to measure the 2-D (R,Z) structure of the divertor plasma in a systematic way using new diagnostics. Measurements cover the divertor radially from inside the X-point to the outer target plate and vertically from the target plate to above the X-point. Identical, repeatable shots were made, each having radial sweeps of the X-point and divertor strike points, to allow complete plasma and radiation profile measurements. Data have been obtained in ohmic, L-mode, ELMing H-mode, and reversed B{sub T} operation ({gradient}B drift away from the X-point). In addition, complete measurements were made of radiative divertor plasmas with a Partially Detached Divertor (PDD) induced by D{sub 2} injection and with a Radiating Mantle induced by Impurity injection (RMI) using neon and nitrogen. The data set includes first observations of the radial and poloidal profiles of the X-point, inner and outer leg plasmas in PDD and RMI radiative divertor operation. Preliminary data analysis shows that intrinsic impurities play a critical role in determining the SOL and divertor conditions.
MAZE: an input generator for DYNA2D and NIKE2D
Hallquist, J.O.
1983-06-01
MAZE is an interactive program that has been developed as an input generator for DYNA2D, NIKE2D, and possibly other codes through the standard grid link file, SGLF. The purpose of this report is to provide a user's manual.
Timescales of IP3-Evoked Ca2D Spikes Emerge from Ca2D
Parker, Ian
Timescales of IP3-Evoked Ca2D Spikes Emerge from Ca2D Puffs Only at the Cellular Level Kevin behavior generates cellular behavior. Ca2ţ signaling by inositol trisphosphate receptors (IP3R) offers interactions between IP3R. Ca2ţ released by a cluster of IP3R (giving a local Ca2ţ puff) diffuses and ignites
Oscillating flow in a 2-D diffuser
Cameron V. King; Barton L. Smith
Separating oscillating flows in an internal, adverse pressure gradient geometry are studied experimentally. Simultaneous velocity\\u000a and pressure measurements demonstrate that the minor losses associated with oscillating flow in an adverse pressure gradient\\u000a geometry can be smaller or larger than those for steady flow. Separation is found to begin high in the diffuser and propagate\\u000a downward. The flow is able to
Animation : 2D versus 3D and their combined effect
Au, Kristin C
2014-01-01
This thesis studies the differences in the perception of space and character movement between 2D and 3D animation. 2D animation is defined by elements constructed in a 2D environment while 3D animation by elements constructed ...
Raman Spectroscopy Using a Tilted 2D MOT
NASA Astrophysics Data System (ADS)
Kwolek, Jonathan M.; Knutson, Erin; Narducci, Frank A.
2014-05-01
We demonstrate Raman spectroscopy using a cold and continuous beam of Rubidium atoms from a vapor-loaded, tilted two-dimensional magneto optical trap (2D MOT). The atoms emerge through a pinhole into an ultra-high vacuum chamber, and form a cold and slow moving beam of atoms with flux 109 atoms/sec with a most probable velocity of 10 m/s. The atoms travel across a set of laser beams which include an on-resonant state preparation beam, a beam tuned to drive a stimulated Raman transition, and another on-resonant readout beam. We observed Raman spectra which can include as many as 11 peaks. The width of the clock transition is consistent with the transit time of the atoms through the Raman fields. The width of the magnetic transitions is determined by laboratory magnetic noise. We have measured Rabi cycling on the clock transition using Raman beams in a co-propagating geometry by varying the laser power rather than pulse duration. Further developments will be made by introducing a momentum kick by using Raman beams in a counter-propagating geometry. Office of Naval Research.
Phase velocity in 2D TTI media
NASA Astrophysics Data System (ADS)
Xuan, Yihua; He, Qiaodeng; Lin, Yan
2007-03-01
We derive an expression for phase velocity in 2D tilted transverse isotropy (TTI) media. Snapshots of phase velocity in TTI and transverse isotropy (TI) model media are simulated and analyzed using the derived expression. In addition, the x-component character differences between the modeled phase velocities of the two media models are compared and analyzed.
Hopkinson bar simulation using DYNA2D
Smith, J.A.; Glover, T.A.
1985-01-08
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.
Structural Bifurcation of 2-D Incompressible Flows
Ghil, Michael
topological aspects of hydrodynamics, and Brenier [4, 5] for volume-preserving maps and generalized solutions). This article is part of a program to develop a geo- metric theory for the Lagrangian dynamics of 2-D very fortunate to be part of the Foias-Temam school of fluid dynamics since the early 1990s. Both
Intermittent transport in 2D electrostatic turbulence
Yanick Sarazin; Sadruddin Benkadda; Xavier Garbet; Philippe Ghendrih; George Zaslavsky
1998-01-01
This paper reports 2D fluid simulations of particle turbulent transport in the Scrape-off-layer of a tokamak driven by the interchange instability. The transport dynamics in the gradient driven case (GD) is compared with the one resulting from a flux drive of the system (FD). In the standard GD approach, the poloidally averaged radial transport is found to be homogeneous. Inverse
2D gravity and random matrices
P. Di Francesco; P. Ginsparg; J. Zinn-Justin
1995-01-01
We review recent progress in 2D gravity coupled to d < 1 conformal matter, based on a representation of discrete gravity in terms of random matrices. We discuss the saddle point approximation for these models, including a class of related O(n) matrix models. For d < 1 matter, the matrix problem can be completely solved in many cases by the
NIST HANDBOOK 150-2D Accreditation
NIST HANDBOOK 150-2D National Voluntary Laboratory Accreditation Program Calibration Laboratories. Permission to use the term and/or logo is granted to NVLAP-accredited laboratories for the limited purposes of announcing their accredited status, and for use on reports that describe only testing and calibration within
Simulations of 2D and 3D Scaled Supernova Jet Experiments at Omega*
NASA Astrophysics Data System (ADS)
Wilde, B. H.; Edwards, M. J.; Rosen, P. A.; Foster, J. M.; Remington, B. A.; Perry, T. S.
2001-10-01
Over the last few years we have fielded numerous jet experiments on the NOVA and OMEGA lasers (invited talk by Foster et al., this conference). We are now transitioning these experiments to more closely simulate scaled supernova jets during the explosion phase. In particular, we have fielded shots on OMEGA that investigate the difference between jets created by ablating a 3D (r,z) cylindrical pin versus a 2D (x,y) finite linear ridge. The Brominated CH pin or ridge is mounted symmetrically on the axis at the end of a laser-heated halfraum such that the radiation ablation is symmetric. The jet enters a cylinder of carbon foam and transmission radiographs are taken at different times and at two angles perpendicular to the symmetry axis. The LLNL 2-dimensional ALE and the LANL 3-dimensional Adaptive-Mesh-Refinement RAGE codes were used to design these experiments. Although 2-dimensional calculations are sufficient for the 3D cylindrical pin, 3-dimensional calculations are required for the 2D linear ridge due to its finite nature. To minimize 3-dimensional effects for the ridge, only the central section was Brominated with the ends made out of polyimide at the same density. Brominated and polyimide parts were also used in the pin to act as tagging that allows tracking the motion of different parts of the pin. In this poster, the calculations by the different codes will be compared to each other and to the data. These kinds of jet experiments should prove to be useful as validation for the new 3-dimensional codes being developed by the astrophysical community. *This work is performed under the auspices of the U. S. Department of Energy by the Los Alamos National Laboratory Laboratory under Contract No. W-7405-ENG-36, Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48, and the Laboratory for Laser Energetics under Contract No. DE-FC03-92SF19460.
NASA Astrophysics Data System (ADS)
Chernogorova, T. P.; Temelkov, K. A.; Koleva, N. K.; Vuchkov, N. K.
2014-05-01
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.
NSDL National Science Digital Library
Frame, Michael
This is one of the best online resources about fractals, and is "meant to support a first course in fractal geometry for students without especially strong mathematical preparation." The site is incredibly deep, providing everything from the most basic definitions and non-technical discussions to involved mathematical formulations. Interactive Java applets, downloadable software for the PC and Macintosh, and laboratory activities are also presented. A particularly interesting section of the site explores about 100 places in nature and society where fractals are found.
2d (0,2) Quiver Gauge Theories and D-Branes
Franco, Sebastian; Lee, Sangmin; Seong, Rak-Kyeong; Yokoyama, Daisuke
2015-01-01
We initiate a systematic study of 2d (0,2) quiver gauge theories on the worldvolume of D1-branes probing singular toric Calabi-Yau 4-folds. We present an algorithm for efficiently calculating the classical mesonic moduli spaces of these theories, which correspond to the probed geometries. We also introduce a systematic procedure for constructing the gauge theories for arbitrary toric singularities by means of partial resolution, which translates to higgsing in the field theory. Finally, we introduce Brane Brick Models, a novel class of brane configurations that consist of D4-branes suspended from an NS5-brane wrapping a holomorphic surface, tessellating a 3-torus. Brane Brick Models are the 2d analogues of Brane Tilings and allow a direct connection between geometry and gauge theory.
3D reconstruction of a carotid bifurcation from 2D transversal ultrasound images.
Yeom, Eunseop; Nam, Kweon-Ho; Jin, Changzhu; Paeng, Dong-Guk; Lee, Sang-Joon
2014-12-01
Visualizing and analyzing the morphological structure of carotid bifurcations are important for understanding the etiology of carotid atherosclerosis, which is a major cause of stroke and transient ischemic attack. For delineation of vasculatures in the carotid artery, ultrasound examinations have been widely employed because of a noninvasive procedure without ionizing radiation. However, conventional 2D ultrasound imaging has technical limitations in observing the complicated 3D shapes and asymmetric vasodilation of bifurcations. This study aims to propose image-processing techniques for better 3D reconstruction of a carotid bifurcation in a rat by using 2D cross-sectional ultrasound images. A high-resolution ultrasound imaging system with a probe centered at 40MHz was employed to obtain 2D transversal images. The lumen boundaries in each transverse ultrasound image were detected by using three different techniques; an ellipse-fitting, a correlation mapping to visualize the decorrelation of blood flow, and the ellipse-fitting on the correlation map. When the results are compared, the third technique provides relatively good boundary extraction. The incomplete boundaries of arterial lumen caused by acoustic artifacts are somewhat resolved by adopting the correlation mapping and the distortion in the boundary detection near the bifurcation apex was largely reduced by using the ellipse-fitting technique. The 3D lumen geometry of a carotid artery was obtained by volumetric rendering of several 2D slices. For the 3D vasodilatation of the carotid bifurcation, lumen geometries at the contraction and expansion states were simultaneously depicted at various view angles. The present 3D reconstruction methods would be useful for efficient extraction and construction of the 3D lumen geometries of carotid bifurcations from 2D ultrasound images. PMID:24965564
Fluctuating Pressure Data from 2-D Nozzle Cold Flow Tests (Dual Bell)
NASA Technical Reports Server (NTRS)
Nesman, Tomas E.
2001-01-01
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.
2D dynamics of a drop falling in a miscible fluid
A. Garcimartín; H. L. Mancini; C. Pérez-García
1992-01-01
The dynamics of the fragmentation of a liquid drop falling in a miscible fluid is studied in a Hele-Shaw geometry. We show that this configuration allows quantitative measurements of the characteristic sedimentation velocity and internal velocity of the drop. The break-up process observed in 3D is also found in this quasi-2D configuration. The relation between the internal circulation pattern and
Influence of E × B and ? B drift terms in 2-D edge\\/SOL transport simulations
T. D. Rognlien; G. D. Porter; D. D. Ryutov
1999-01-01
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
Hierarchical 2D Mesh Representation, Tracking and Compression for Object-Based Video
Peter Van Beek; A. Murat Tekalp; Ning Zhuang; Isil Celasun; Minghui Xia
1998-01-01
This paper proposes methods for designing, tracking and coding hierarchical 2D content-based meshrepresentations. The design procedure consists of constructing a fine-to-coarse hierarchy of Delaunaymeshes, using image- and shape-based criteria for mesh geometry simplification. Hierarchical trackingemploys a coarse-to-fine strategy with mesh-based motion vector optimization. We introduce new techniquesto maintain the initial mesh hierarchy and topology during tracking by imposing certain...
Interrogating Fiber Formation Kinetics with Automated 2D-IR Spectroscopy
NASA Astrophysics Data System (ADS)
Strasfeld, David B.; Ling, Yun L.; Shim, Sang-Hee; Zanni, Martin T.
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.
NASA Astrophysics Data System (ADS)
Gusakov, E. Z.; Irzak, M. A.; Popov, A. Yu; Teplova, N. V.
2015-07-01
Computational analysis of radial correlation reflectometry in the framework of a model accounting for 2D probing wave propagation and scattering is performed. The procedure of the turbulence wavenumber spectra reconstruction from radial correlation reflectometry data previously proposed in the case of normal incidence of probing wave onto the 1D plasma is justified for the real geometry of a reflectometry experiment at large and modest scale fusion plasmas.
CLOSED-FORM AUTOMATICALLY PAIRED 2-D DIRECTION-OF-ARRIVAL ESTIMATION WITH ARBITRARY ARRAYS
T. Filik; T. Engin Tuncer
2009-01-01
A new approach is proposed for two-dimensional (2-D) direction-of-arrival (DOA) estimation with arbitrary array geometries. The proposed method is based on array inter- polation and it provides automatically paired source azimuth and elevation angle estimates. It is a fast algorithm and there is no need for search. In addition, the number of sensors re- quired for such an operation is
Extended Aperture 2-D Direction Finding With a Two-Parallel-Shape-Array Using Propagator Method
Jin He; Zhong Liu
2009-01-01
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
Experimental evaluation of a 2D and 3D electron pencil beam algorithm
E. Mah; J. Antolak; J. W. Scrimger; J. J. Battista
1989-01-01
Verification of electron beam treatment-planning algorithms in the presence of heterogeneities can be very difficult. Using controlled geometries to minimise physical uncertainties in geometric alignment and composition, a large number of measurements were made to test the performance of a 2D and 3D electron pencil beam algorithm. A Therados RFA-3 beam-scanning system interfaced to a microcomputer was used to measure
Rotating convection in elliptical geometries
NASA Astrophysics Data System (ADS)
Evonuk, M.
2014-12-01
Tidal interactions between hot jupiter planets and their host stars are likely to result in non-spherical geometries. These elliptical instabilities may have interesting effects on interior fluid convective patterns, which in turn influence the nature of the magnetic dynamo within these planets. Simulations of thermal convection in the 2D rotating equatorial plane are conducted to determine to first order the effect of ellipticity on convection for varying density contrasts with differing convective vigor and rotation rate. This survey is conducted in two dimensions in order to simulate a broad range of ellipticities and to maximize the parameter space explored.
ERAST Demonstrator 2 (D-2) in flight
NASA Technical Reports Server (NTRS)
1996-01-01
ERAST Demonstrator 2 (D-2) in flight during 1996. The Demonstrator 2 (D-2) was built by Scaled Composites of Mojave, California, to test remote flight-control capabilities. As a result, it had only limited provisions for a scientific payload. The D-2 was also unusual in that it could be flown by either a pilot in an open cockpit or by remote control. It was powered by a 100-horsepower Rotax 914 piston engine turning a three-bladed propeller. It late 1996, it was flown to test the vehicle's ability to communicate over the horizon using a Tracking and Data Relay Satellite. The D-2 resumed flights in August 1998 to test a triply-redundant flight control system that would allow remotely piloted high-altitude missions.
Supersymmetric Extension of GCA in 2d
Mandal, Ipsita
2010-01-01
We derive the infinite dimensional Supersymmetric Galilean Conformal Algebra (SGCA) in the case of two spacetime dimensions by performing group contraction on 2d superconformal algebra. We also obtain the representations of the generators in terms of superspace coordinates. Here we find realisations of the SGCA by considering scaling limits of certain 2d SCFTs which are non-unitary and have their left and right central charges become large in magnitude and opposite in sign. We focus on the Neveu-Schwarz sector of the parent SCFTs and develop, in parallel to the GCA studies recently in (arXiv:0912.1090), the representation theory based on SGCA primaries, Ward identities for their correlation functions and their descendants which are null states.
Realistic and efficient 2D crack simulation
NASA Astrophysics Data System (ADS)
Yadegar, Jacob; Liu, Xiaoqing; Singh, Abhishek
2010-04-01
Although numerical algorithms for 2D crack simulation have been studied in Modeling and Simulation (M&S) and computer graphics for decades, realism and computational efficiency are still major challenges. In this paper, we introduce a high-fidelity, scalable, adaptive and efficient/runtime 2D crack/fracture simulation system by applying the mathematically elegant Peano-Cesaro triangular meshing/remeshing technique to model the generation of shards/fragments. The recursive fractal sweep associated with the Peano-Cesaro triangulation provides efficient local multi-resolution refinement to any level-of-detail. The generated binary decomposition tree also provides efficient neighbor retrieval mechanism used for mesh element splitting and merging with minimal memory requirements essential for realistic 2D fragment formation. Upon load impact/contact/penetration, a number of factors including impact angle, impact energy, and material properties are all taken into account to produce the criteria of crack initialization, propagation, and termination leading to realistic fractal-like rubble/fragments formation. The aforementioned parameters are used as variables of probabilistic models of cracks/shards formation, making the proposed solution highly adaptive by allowing machine learning mechanisms learn the optimal values for the variables/parameters based on prior benchmark data generated by off-line physics based simulation solutions that produce accurate fractures/shards though at highly non-real time paste. Crack/fracture simulation has been conducted on various load impacts with different initial locations at various impulse scales. The simulation results demonstrate that the proposed system has the capability to realistically and efficiently simulate 2D crack phenomena (such as window shattering and shards generation) with diverse potentials in military and civil M&S applications such as training and mission planning.
Surface modelling for 2D imagery
Lieng, Henrik
2014-11-11
for creating graphics typically emulate traditional painting media and support additional features such as undo and layering. Whether such digital tools achieve this simulation is a hot debate among artistsi. Those in favour for a digital revolution envision... . . . . . . . . . . . . . . . . Chapter 1 Introduction Digital design and creation of 2D imagery targets many applications, ranging from industrial and medical problems to artistic applications. The research presented in this dissertation in- volves the investigation of novel approaches...
MAGNUM-2D computer code: user's guide
England, R.L.; Kline, N.W.; Ekblad, K.J.; Baca, R.G.
1985-01-01
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.
Tomosynthesis imaging with 2D scanning trajectories
NASA Astrophysics Data System (ADS)
Khare, Kedar; Claus, Bernhard E. H.; Eberhard, Jeffrey W.
2011-03-01
Tomosynthesis imaging in chest radiography provides volumetric information with the potential for improved diagnostic value when compared to the standard AP or LAT projections. In this paper we explore the image quality benefits of 2D scanning trajectories when coupled with advanced image reconstruction approaches. It is intuitively clear that 2D trajectories provide projection data that is more complete in terms of Radon space filling, when compared with conventional tomosynthesis using a linearly scanned source. Incorporating this additional information for obtaining improved image quality is, however, not a straightforward problem. The typical tomosynthesis reconstruction algorithms are based on direct inversion methods e.g. Filtered Backprojection (FBP) or iterative algorithms that are variants of the Algebraic Reconstruction Technique (ART). The FBP approach is fast and provides high frequency details in the image but at the same time introduces streaking artifacts degrading the image quality. The iterative methods can reduce the image artifacts by using image priors but suffer from a slow convergence rate, thereby producing images lacking high frequency details. In this paper we propose using a fast converging optimal gradient iterative scheme that has advantages of both the FBP and iterative methods in that it produces images with high frequency details while reducing the image artifacts. We show that using favorable 2D scanning trajectories along with the proposed reconstruction method has the advantage of providing improved depth information for structures such as the spine and potentially producing images with more isotropic resolution.
NASA Astrophysics Data System (ADS)
Ideses, Ianir A.; Yaroslavsky, Leonid P.
2006-02-01
In this paper, we present methods to synthesize 3D video from arbitrary 2D video. The 2D video is analyzed by computing frame-by-frame motion maps. For this computation, several methods were tested, including optical flow, segmentation and correlation based target location. Using the computed motion maps, the video undergoes analysis and the frames are segmented to provide object-wise depth ordering. The frames are then used to synthesize stereo pairs. This is performed by resampling frames on a grid that is governed by a corresponding depth-map. In order to improve the quality of the synthetic video, as well as to enable 2D viewing where 3D visualization is not possible, several techniques for image enhancement are used. In our test case, anaglyph projection was selected as the 3D visualization method, as the method is mostly suited to standard displays. The drawback of this method is ghosting artifacts. In our implementation we minimize these unwanted artifacts by modifying the computed depth-maps using non-linear transformations. Defocusing of one anaglyph color component was also used to counter such artifacts. Our results show that the suggested methods enable synthesis of high quality 3D videos.
NASA Astrophysics Data System (ADS)
Ideses, Ianir A.; Yaroslavsky, Leonid P.; Fishbain, Barak; Vistuch, Roni
2007-02-01
In this paper, we present an efficient method to synthesize 3D video from compressed 2D video. The 2D video is analyzed by computing frame-by-frame motion maps. For this computation, MPEG motion vectors extraction was performed. Using the extracted motion vector maps, the video undergoes analysis and the frames are segmented to provide object-wise depth ordering. The frames are then used to synthesize stereo pairs. This is performed by resampling the video frames on a grid that is governed by a corresponding depth-map. In order to improve the quality of the synthetic video, as well as to enable 2D viewing where 3D visualization is not possible, several techniques for image enhancement are used. In our test case, anaglyph projection was selected as the 3D visualization method, as the method is mostly suited to standard displays. The drawback of this method is ghosting artifacts. In our implementation we minimize these unwanted artifacts by modifying the computed depth-maps using non-linear transformations. Defocusing of one anaglyph color component was also used to counter such artifacts. Our results show that the suggested methods enable synthesis of high quality 3D videos in real-time.
2D Projection Interval Relationships: A Symbolic Representation
Ngu, Anne H.H. - Department of Computer Science, Texas State University
2D Projection Interval Relationships: A Symbolic Representation of Spatial Relationships Mohammad we propose a uni ed representation of spatial relationships, 2D Projection Interval Relationships (2D that is based on 2D-PIR. This graph representation can be constructed e ciently and leads to an e cient
Casimir effects in systems containing 2D layers such as graphene and 2D electron gases
NASA Astrophysics Data System (ADS)
Sernelius, B. E.
2015-06-01
We present a variety of methods to derive the Casimir interaction in planar systems containing 2D layers. Examples where this can be of use is graphene, graphene-like layers and 2D electron gases. We present results for two free standing layers and for one layer above a substrate. The results can easily be extended to systems with a larger number of layers.
MAZE: an input generator for DYNA2D and NIKE2D
Hallquist, J.O.
1982-03-01
MAZE is an interactive program that has been developed as an input generator for DYNA2D and NIKE2D; however, the generated mesh file is compatible with other finite element programs as well. The purpose of this report is to provide a user's manual. Since the development is ongoing, users are invited and encouraged to make suggestions concerning any options or features that they would like added.
Casimir effects in systems containing 2D layers such as graphene and 2D electron gases.
Sernelius, B E
2015-06-01
We present a variety of methods to derive the Casimir interaction in planar systems containing 2D layers. Examples where this can be of use is graphene, graphene-like layers and 2D electron gases. We present results for two free standing layers and for one layer above a substrate. The results can easily be extended to systems with a larger number of layers. PMID:25965400
Atoms dictating shape: The discrete geometry of conformal two-dimensional materials
NASA Astrophysics Data System (ADS)
Mehboudi, Mehrshad; Utt, Kainen; Terrones, Humberto; Pacheco, Alejandro; Harriss, Edmund; Barraza-Lopeez, Salvador
2015-03-01
The electronic, optical, thermal, mechanical and chemical behavior of two-dimensional (2D) materials depends on their shape (geometry). 2D materials are nets, with covalent bonds representing edges, and where atoms are vertices. Here we use a mathematical language to tell the shape of meshes and discuss the geometry of 2D materials of varied lattice structures, such as: hexagonal boron nitride, black phosphorus monolayers, low-buckled silicene, germanene, blue phosphorous, newly predicted III-V buckled 2D compounds such as AlP, conformal ``thicker'' layered materials such as 2D tin, ``single-layer'' transition metal dichalcogenides (MX2's), and a single-quintuple-layer of the topological insulator Bi2Se3. We characterize the geometry of each atom position without recourse to a continuum parametric model. The new framework generalizes the discrete geometry we introduced recently for graphene.
Slab detachment - 3-D versus 1-D & 2-D
NASA Astrophysics Data System (ADS)
von Tscharner, Marina; Duretz, Thibault; Schmalholz, Stefan
2014-05-01
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
A 2-D ECG compression algorithm based on modified SPIHT
Zhelong Wang; Pengfu Zhu; Ying Chen
2008-01-01
A new two-dimensional (2-D) Electrocardiogram (ECG) signal compression algorithm named 2D Modified Set Partitioning In Hierarchical Trees (2-D MSPIHT), which is based on the SPIHT algorithm, has been proposed in this paper. According to the two correlativity of ECG signal, an ECG signal is cut and aligned to form a 2-D data array, and then 2-D MSPIHT can be applied.
WFR-2D: an analytical model for PWAS-generated 2D ultrasonic guided wave propagation
NASA Astrophysics Data System (ADS)
Shen, Yanfeng; Giurgiutiu, Victor
2014-03-01
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.
2-D or not 2-D, that is the question: A Northern California test
Mayeda, K; Malagnini, L; Phillips, W S; Walter, W R; Dreger, D
2005-06-06
Reliable estimates of the seismic source spectrum are necessary for accurate magnitude, yield, and energy estimation. In particular, how seismic radiated energy scales with increasing earthquake size has been the focus of recent debate within the community and has direct implications on earthquake source physics studies as well as hazard mitigation. The 1-D coda methodology of Mayeda et al. has provided the lowest variance estimate of the source spectrum when compared against traditional approaches that use direct S-waves, thus making it ideal for networks that have sparse station distribution. The 1-D coda methodology has been mostly confined to regions of approximately uniform complexity. For larger, more geophysically complicated regions, 2-D path corrections may be required. The complicated tectonics of the northern California region coupled with high quality broadband seismic data provides for an ideal ''apples-to-apples'' test of 1-D and 2-D path assumptions on direct waves and their coda. Using the same station and event distribution, we compared 1-D and 2-D path corrections and observed the following results: (1) 1-D coda results reduced the amplitude variance relative to direct S-waves by roughly a factor of 8 (800%); (2) Applying a 2-D correction to the coda resulted in up to 40% variance reduction from the 1-D coda results; (3) 2-D direct S-wave results, though better than 1-D direct waves, were significantly worse than the 1-D coda. We found that coda-based moment-rate source spectra derived from the 2-D approach were essentially identical to those from the 1-D approach for frequencies less than {approx}0.7-Hz, however for the high frequencies (0.7{le} f {le} 8.0-Hz), the 2-D approach resulted in inter-station scatter that was generally 10-30% smaller. For complex regions where data are plentiful, a 2-D approach can significantly improve upon the simple 1-D assumption. In regions where only 1-D coda correction is available it is still preferable over 2-D direct wave-based measures.
2D packing using the Myriad framework
NASA Astrophysics Data System (ADS)
Chatburn, Luke T.; Batchelor, Bruce G.
2004-02-01
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.
2D axisymmetric analysis of SRM ignition transient
NASA Technical Reports Server (NTRS)
Bai, S. D.; Han, Samuel S.; Pardue, B. A.
1993-01-01
To analyze ignition transient of Space Shuttle solid rocket motor, a transient two-dimensional numerical model based on turbulent compressible Navier-Stokes equations in a generalized coordinate system was developed. One-dimensional numerical models (Peretz et al., 1973; Han, 1992; Pardue and Han, 1992) with empirical correlations data obtained from steady turbulent boundary layer flows agrees reasonably well with test rocket data by adjusting a few parameters. However, a 1D model can not provide a physical insight into the complex multidimensional thermal fields and flowfields in the chamber and the converging-diverging rocket nozzle. As an interim step, a 2D model was developed and compared with test data. A modified version of SIMPLE algorithm was used for the numerical model, and the standard k-epsilon model with a wall function was used for turbulence closure. Transient flowfields and thermal fields in the combustion chamber and the attached nozzle were obtained for a selected rocket geometry and propellant. Transient behaviors of the flow and thermal fields were analyzed, and were found to be in good agreement with physical expectations.
2D Fluidization of Nanomaterials by Biomimetic Membranes
NASA Astrophysics Data System (ADS)
Kelly, Kathleen; Forstner, Martin
2012-02-01
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.
Howard Georgi; Yevgeny Kats
2008-05-26
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 scale invariant theory with nontrivial anomalous dimensions at low energies. We construct a toy standard model coupling to the fermions in the Sommerfield model and study how the transition from unparticle behavior at low energies to free particle behavior at high energies manifests itself in interactions with the toy standard model particles.
2D Electrostatic Actuation of Microshutter Arrays
NASA Technical Reports Server (NTRS)
Burns, Devin E.; Oh, Lance H.; Li, Mary J.; Jones, Justin S.; Kelly, Daniel P.; Zheng, Yun; Kutyrev, Alexander S.; Moseley, Samuel H.
2015-01-01
An electrostatically actuated microshutter array consisting of rotational microshutters (shutters that rotate about a torsion bar) were designed and fabricated through the use of models and experiments. Design iterations focused on minimizing the torsional stiffness of the microshutters, while maintaining their structural integrity. Mechanical and electromechanical test systems were constructed to measure the static and dynamic behavior of the microshutters. The torsional stiffness was reduced by a factor of four over initial designs without sacrificing durability. Analysis of the resonant behavior of the microshutter arrays demonstrates that the first resonant mode is a torsional mode occurring around 3000 Hz. At low vacuum pressures, this resonant mode can be used to significantly reduce the drive voltage necessary for actuation requiring as little as 25V. 2D electrostatic latching and addressing was demonstrated using both a resonant and pulsed addressing scheme.
Canard configured aircraft with 2-D nozzle
NASA Technical Reports Server (NTRS)
Child, R. D.; Henderson, W. P.
1978-01-01
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.
Simple 2-D navigation for wheeled vehicles
Klarer, P.R.
1988-04-01
This paper describes a simple algorithm to perform navigation in a two-dimensional world model. The algorithm utilizes a simple geometric approach which is first applied to a bicycle. The equations are then expanded to apply to 3- and 4-wheeled vehicles with ''conventional'' steering mechanisms (such as the Ackerman steering geometry in the 4-wheeled case). Calculations for omnidirectional robots which utilize differential odometry and differential drive are described as well. Practical considerations and sources of error are discussed, as are possible extensions of this method to a three-dimensional world model. 5 refs., 8 figs.
Simple 2-D navigation for wheeled vehicles
Klarer, P.R.
1988-01-01
This paper describes a simple algorithm to perform navigation in a two-dimensional world model. The algorithm utilizes a simple geometric approach which is first applied to a bicycle. The equations are then expeanded to apply to 3- and 4-wheeled vehicles with ''conventional'' steering mechanism (such as the Ackerman steering geometry in the 4-wheeled case). Calculations for omnidirectional robots which utilize differential odometry and differential drive are described as well. Practical considerations and sources of error are discussed, as are possible extensions of this method to a three-dimensional world model. 5 refs., 8 figs.
Comprehensive 2D measurements of radiative divertor plasmas in DIII-D
Fenstermacher, M.E.; Wood, R.D.; Allen, S.L.; Hill, D.N. [and others
1997-07-01
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.
Reactive 2D\\/3D garment pattern design modification
Ze Gang Luo; Matthew Ming-fai Yuen
2005-01-01
This paper presents a new 3D garment simulation result update algorithm for the 2D garment pattern design modification. The proposed algorithm enables the 3D garment fitting simulation result directly to react to the modification in the 2D patterns. The algorithm performs a topological invariant deformation of the 2D pattern mesh after the boundary of the 2D pattern undergoes a topological
Simplified 2D Bidomain Model of Whole Heart Electrical Activity and ECG Generation
NASA Astrophysics Data System (ADS)
Sovilj, Siniša; Magjarevi?, Ratko; Abed, Amr Al; Lovell, Nigel H.; Dokos, Socrates
2014-06-01
The aim of this study was the development of a geometrically simple and highly computationally-efficient two dimensional (2D) biophysical model of whole heart electrical activity, incorporating spontaneous activation of the sinoatrial node (SAN), the specialized conduction system, and realistic surface ECG morphology computed on the torso. The FitzHugh-Nagumo (FHN) equations were incorporated into a bidomain finite element model of cardiac electrical activity, which was comprised of a simplified geometry of the whole heart with the blood cavities, the lungs and the torso as an extracellular volume conductor. To model the ECG, we placed four electrodes on the surface of the torso to simulate three Einthoven leads VI, VII and VIII from the standard 12-lead system. The 2D model was able to reconstruct ECG morphology on the torso from action potentials generated at various regions of the heart, including the sinoatrial node, atria, atrioventricular node, His bundle, bundle branches, Purkinje fibers, and ventricles. Our 2D cardiac model offers a good compromise between computational load and model complexity, and can be used as a first step towards three dimensional (3D) ECG models with more complex, precise and accurate geometry of anatomical structures, to investigate the effect of various cardiac electrophysiological parameters on ECG morphology.
1 function fe2d_d 2 % 'fe2d_d.m' 2D finite element Matlab code for Scheme 2 applied
Garvie, Marcus R
1 function fe2d_d 2 % 'fe2d_d.m' 2D finite element Matlab code for Scheme 2 applied 3 % to the predator-prey system with Kinetics 1. The nodes and elements 4 % of the unstructured grid are loaded from_coord)'; 20 % Read in 't(3,no_elems)', the list of nodes for 'no_elems' elements 21 load t_triang.dat -ascii
Relative Affine Structure: Canonical Model for 3D From 2D Geometry and Applications
Amnon Shashua; Nassir Navab
1996-01-01
. We propose an affine framework for perspective views, capturedby a single extremely simple equation based on a viewer-centeredinvariant we call relative affine structure. Via a number of corollaries ofour main results we show that our framework unifies previous work --- includingEuclidean, projective and affine --- in a natural and simple way,and introduces new, extremely simple, algorithms for the tasks
Linear line spectropolarimetry as a new window to measure 2D and 3D wind geometries
NASA Astrophysics Data System (ADS)
Vink, Jorick S.
2015-01-01
Various theories have been proposed to predict how mass loss depends on the stellar rotation rate, both in terms of its strength, as well as its latitudinal dependence, crucial for our understanding of angular momentum evolution. Here we discuss the tool of linear spectropolarimetry that can probe the difference between mass loss from the pole versus the equator. Our results involve several groups of O stars and Wolf-Rayet stars, involving Oe stars, Of?p stars, Onfp stars, as well as the best candidate gamma-ray burst progenitors identified to date.
Decaying 2D Turbulence in Bounded Domains: Influence of the Geometry
École Normale Supérieure
time behaviour of the flow. Typically one observes the formation of stable large scale structures which simulation of two-dimensional decaying tur- bulence in wall bounded domains. The NavierStokes equations decay 1 Introduction Twodimensional turbulence in wall bounded domains has many applications
Automatic 2D-3D Registration Student: Lingyun Liu
Stamos, Ioannis
Automatic 2D-3D Registration Student: Lingyun Liu Advisor: Prof. Ioannis Stamos #12;Abstract: Given 3D model constructed from range images of a real-world scene and set of 2D images, we want to apply textures from those 2D images to the model automatically. We propose an approach that uses line features
Lee, In-Kwon
1 2012 2D 3D * 0 , 1 , 2 0,2 1 ( 0 skrcjstk, 2 iklee)@yonsei.ac.kr 1 rinthel Science, Yonsei University. 1 Dept. of Information Media, The University of Suwon. 2D 3D . 2D - , 3D (Disparity) 3D . . 1. 3D 3D . 3D 3D [1
NISTIR 7668 A Collection of 2D Elliptic
Mitchell, William F.
NISTIR 7668 A Collection of 2D Elliptic Problems for Testing Adaptive Algorithms William F of 2D Elliptic Problems for Testing Adaptive Algorithms William F. Mitchell Mathematical problems. 2D elliptic problems are often used as the first test bed for new algorithms and codes
Top2maya A Tool for Converting 2D Topographical
Illinois at Urbana-Champaign, University of
Top2maya A Tool for Converting 2D Topographical Maps to 3D Models Rob Gillespie Student techreports@itg.uiuc.edu http://www.itg.uiuc.edu #12;Top2maya A Tool for Converting 2D Topographical Maps@itg.uiuc.edu Top2maya is a program written in MEL script which changes 2D topographical maps into three
Top2maya A Tool for Converting 2D Topographical
Illinois at Urbana-Champaign, University of
Top2maya A Tool for Converting 2D Topographical Maps to 3D Models Rob Gillespie, Consultant 61801 techreports@itg.uiuc.edu http://www.itg.uiuc.edu #12;Top2maya A Tool for Converting 2D top2maya Top2maya is a program written in MEL script which changes 2D topographical maps into three
FPGA Implementation of 2D FDTD Algorithm A Thesis Presented
Leeser, Miriam
FPGA Implementation of 2D FDTD Algorithm A Thesis Presented by Wang Chen to The Department Graduate School of Engineering Thesis Title: FPGA Implementation of 2D FDTD Algorithm. Author: Wang Chen;NORTHEASTERN UNIVERSITY Graduate School of Engineering Thesis Title: FPGA Implementation of 2D FDTD Algorithm
Influence of individual cell motility on the 2D front roughness dynamics of tumour cell colonies.
Muzzio, N E; Pasquale, M A; González, P H; Arvia, A J
2014-06-01
The dynamics of in situ 2D HeLa cell quasi-linear and quasi-radial colony fronts in a standard culture medium is investigated. For quasi-radial colonies, as the cell population increased, a kinetic transition from an exponential to a constant front average velocity regime was observed. Special attention was paid to individual cell motility evolution under constant average colony front velocity looking for its impact on the dynamics of the 2D colony front roughness. From the directionalities and velocity components of cell trajectories in colonies with different cell populations, the influence of both local cell density and cell crowding effects on individual cell motility was determined. The average dynamic behaviour of individual cells in the colony and its dependence on both local spatio-temporal heterogeneities and growth geometry suggested that cell motion undergoes under a concerted cell migration mechanism, in which both a limiting random walk-like and a limiting ballistic-like contribution were involved. These results were interesting to infer how biased cell trajectories influenced both the 2D colony spreading dynamics and the front roughness characteristics by local biased contributions to individual cell motion. These data are consistent with previous experimental and theoretical cell colony spreading data and provide additional evidence of the validity of the Kardar-Parisi-Zhang equation, within a certain range of time and colony front size, for describing the dynamics of 2D colony front roughness. PMID:24893945
ERIC Educational Resources Information Center
Kuntz, Gilles
The first section of this paper on World Wide Web applications related to dynamic geometry addresses dynamic geometry and teaching, including the relationship between dynamic geometry and direct manipulation, key features of dynamic geometry environments, the importance of direct engagement of the learner using construction software for…
Baldwin, John T.
Analytic Structures Geometry and Categoricity John T. Baldwin January 8, 2012 #12;Geometry and Categoricity Homogeneity Zariski Structures Analytic Structures Whig History #12;Geometry and Categoricity John T. Baldwin in (C, +, Â·) by `analytically' definable. Response #12;Geometry and Categoricity John T. Baldwin
Gideon, Rudy A.
Projective Geometry and Pappus' Theorem Kelly McKinnie History Pappus' Theorem Geometries Picturing Kelly McKinnie History Pappus' Theorem Geometries Picturing the projective plane Lines in projective and Pappus' Theorem Kelly McKinnie History Pappus' Theorem Geometries Picturing the projective plane Lines
Computational Information Geometry From Euclidean to flat Pythagorean geometries
Nielsen, Frank
geometry: Customize geometries to datasets, generic non-Euclidean algorithmic toolboxes. George E. P. BoxComputational Information Geometry From Euclidean to flat Pythagorean geometries Frank Nielsen persistence), Recover intrinsic geometry (eg., distance learning, invariants) Computational information
2D Cooling of Magnetized Neutron Stars
Deborah N. Aguilera; José A. Pons; Juan A. Miralles
2008-04-17
Context: Many thermally emitting isolated neutron stars have magnetic fields larger than 10^13 G. A realistic cooling model that includes the presence of high magnetic fields should be reconsidered. Aims: We investigate the effects of anisotropic temperature distribution and Joule heating on the cooling of magnetized neutron stars. Methods: The 2D heat transfer equation with anisotropic thermal conductivity tensor and including all relevant neutrino emission processes is solved for realistic models of the neutron star interior and crust. Results: The presence of the magnetic field affects significantly the thermal surface distribution and the cooling history during both, the early neutrino cooling era and the late photon cooling era. Conclusions: There is a large effect of the Joule heating on the thermal evolution of strongly magnetized neutron stars. Both magnetic fields and Joule heating play a key role in keeping magnetars warm for a long time. Moreover, this effect is important for intermediate field neutron stars and should be considered in radio-quiet isolated neutron stars or high magnetic field radio-pulsars.
On 2D impurity radiation fronts
NASA Astrophysics Data System (ADS)
Simakov, A. M.; Krasheninnikov, S. I.
1997-11-01
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
2D Radiative Processes Near Cloud Edges
NASA Technical Reports Server (NTRS)
Varnai, T.
2012-01-01
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.
Multiple Stokes wavelength generation in H2, D2, and CH4 for lidar aerosol measurements
NASA Technical Reports Server (NTRS)
Chu, Zhiping; Wilkerson, Thomas D.; Singh, Upendra N.
1991-01-01
Experimental results are reported of multiple Stokes generation of a frequency-doubled Nd:YAG laser in H2, D2, and CH4 in a focusing geometry. The energies at four Stokes orders were measured as functions of pump energy and gas pressure. The characteristics of the Stokes radiation generated in these gases are compared for optical production of multiple wavelengths. The competition between Raman components is analyzed in terms of cascade Raman scattering and four-wave mixing. The results indicate the possibility of using these generation processes for atmospheric aerosol measurements by means of multiwavelength lidar systems. Also, this study distinguishes between the gases, as regards the tendency to produce several wavelengths (H2,D2) versus the preference to produce mainly first Stokes radiation (CH4).
Long-range orientation and atomic attachment of nanocrystals in 2D honeycomb superlattices.
Boneschanscher, M P; Evers, W H; Geuchies, J J; Altantzis, T; Goris, B; Rabouw, F T; van Rossum, S A P; van der Zant, H S J; Siebbeles, L D A; Van Tendeloo, G; Swart, I; Hilhorst, J; Petukhov, A V; Bals, S; Vanmaekelbergh, D
2014-06-20
Oriented attachment of synthetic semiconductor nanocrystals is emerging as a route for obtaining new semiconductors that can have Dirac-type electronic bands such as graphene, but also strong spin-orbit coupling. The two-dimensional (2D) assembly geometry will require both atomic coherence and long-range periodicity of the superlattices. We show how the interfacial self-assembly and oriented attachment of nanocrystals results in 2D metal chalcogenide semiconductors with a honeycomb superlattice. We present an extensive atomic and nanoscale characterization of these systems using direct imaging and wave scattering methods. The honeycomb superlattices are atomically coherent and have an octahedral symmetry that is buckled; the nanocrystals occupy two parallel planes. Considerable necking and large-scale atomic motion occurred during the attachment process. PMID:24948734
Numerical investigation of convection-induced MHD waves interacting with a null point in 2D
NASA Astrophysics Data System (ADS)
Tarr, Lucas A.; Linton, Mark G.; Leake, James
2015-04-01
We use the LaRe2D MHD code to investigate the propagation of waves in a 2D geometry that includes a quadrupolar magnetic field with a single nullpoint. The simulation box spans the upper convection zone to the corona (y=[-3Mm,35.4Mm] ) and includes a stratified atmosphere. We model the upper convection zone by introducing an energy flux at the lower boundary, an ad-hoc Newton-cooling term to simulate the effect of radiation at the photosphere (y=0), and an initial condition that includes density and internal energy perturbations throughout the convection zone. This sets up the superadiabatic temperature gradient necessary to sustain convection and generate waves. We discuss the dynamic properties of these waves as they propagate through the atmosphere and interact at topologically important features of the magnetic field. This work is funded by the Chief of Naval Research.
Pythagoras' Theorem on a 2D-Lattice from a "Natural" Dirac Operator and Connes' Distance Formula
Jian Dai; Xing-Chang Song
2001-01-15
One of the key ingredients of A. Connes' noncommutative geometry is a generalized Dirac operator which induces a metric(Connes' distance) on the state space. We generalize such a Dirac operator devised by A. Dimakis et al, whose Connes' distance recovers the linear distance on a 1D lattice, into 2D lattice. This Dirac operator being "naturally" defined has the so-called "local eigenvalue property" and induces Euclidean distance on this 2D lattice. This kind of Dirac operator can be generalized into any higher dimensional lattices.
A Planar Quantum Transistor Based on 2D-2D Tunneling in Double Quantum Well Heterostructures
Baca, W.E.; Blount, M.A.; Hafich, M.J.; Lyo, S.K.; Moon, J.S.; Reno, J.L.; Simmons, J.A.; Wendt, J.R.
1998-12-14
We report on our work on the double electron layer tunneling transistor (DELTT), based on the gate-control of two-dimensional -- two-dimensional (2D-2D) tunneling in a double quantum well heterostructure. While previous quantum transistors have typically required tiny laterally-defined features, by contrast the DELTT is entirely planar and can be reliably fabricated in large numbers. We use a novel epoxy-bond-and-stop-etch (EBASE) flip-chip process, whereby submicron gating on opposite sides of semiconductor epitaxial layers as thin as 0.24 microns can be achieved. Because both electron layers in the DELTT are 2D, the resonant tunneling features are unusually sharp, and can be easily modulated with one or more surface gates. We demonstrate DELTTs with peak-to-valley ratios in the source-drain I-V curve of order 20:1 below 1 K. Both the height and position of the resonant current peak can be controlled by gate voltage over a wide range. DELTTs with larger subband energy offsets ({approximately} 21 meV) exhibit characteristics that are nearly as good at 77 K, in good agreement with our theoretical calculations. Using these devices, we also demonstrate bistable memories operating at 77 K. Finally, we briefly discuss the prospects for room temperature operation, increases in gain, and high-speed.
A large 2D PSD for thermal neutron detection
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
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.
A large 2D PSD for thermal neutron detection
NASA Astrophysics Data System (ADS)
Knott, R. B.; Smith, G. C.; Watt, G.; Boldeman, J. W.
1997-02-01
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 × 640 mm 2. To meet the specifications for neutron detection efficiency and spatial resolution, and to minimise parallax, the gas mixture was 190 kPa 3He plus 100 kPa CF 4, and the active volume had a thickness of 30 mm. The design maximum neutron count rate of the detector was 10 5 events per secod. The (calculated) neutron detection efficiency was 60% for 2 Ĺ 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 × 5 mm 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 line width 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.
Space Charge Limited 2-d Electron Flow between Two Flat Electrodes in a Strong Magnetic Field
Rokhlenko, A; Lebowitz, Joel L.
2003-01-01
An approximate analytic solution is constructed for the 2-d space charge limited emission by a cathode surrounded by non emitting conducting ledges of width Lambda. An essentially exact solution (via conformal mapping) of the electrostatic problem in vacuum is matched to the solution of a linearized problem in the space charge region whose boundaries are sharp due to the presence of a strong magnetic field. The current density growth in a narrow interval near the edges of the cathode depends strongly on Lambda. We obtain an empirical formula for the total current as a function of Lambda which extends to more general cathode geometries.
The Hartle-Hawking wave function in 2d causal set quantum gravity
Lisa Glaser; Sumati Surya
2014-11-13
We define the Hartle-Hawking no-boundary wave function for causal set quantum gravity over the discrete analogs of spacelike hypersurfaces. Using Markov Chain Monte Carlo and numerical integration methods we analyse this wave function in non perturbative 2d causal set quantum gravity. Our results provide new insights into the role of quantum gravity in the observable universe. We find that non-manifold contributions to the Hartle-Hawking wave function can play a significant role. These discrete geometries exhibit a rapid spatial expansion with respect to the proper time and also possess a spatial homogeneity consistent with our current understanding of the observable universe.
Amoeboid motion in confined geometry
Wu, Hao; Hu, Wei-Fan; Farutin, Alexander; Rafaď, Salima; Lai, Ming-Chih; Peyla, Philippe; Misbah, Chaouqi
2015-01-01
Cells of the immune system, as well as cancer cells, migrating in confined environment of tissues undergo frequent shape changes (described as amoeboid motion) that enable them to move forward through these porous media without the assistance of adhesion sites. In other words, they perform amoeboid swimming (AS) while using extracellular matrices and cells of tissues as support. We introduce a simple model of AS in a confined geometry solved by means of 2D numerical simulations. We find that confinement promotes AS, unless being so strong that it restricts shape change amplitude. A straight AS trajectory in the channel is found to be unstable, and ample lateral excursions of the swimmer prevail. For weak confinement, these excursions are symmetric, while they become asymmetric at stronger confinement, whereby the swimmer is located closer to one of the two walls. This is a spontaneous symmetry-breaking bifurcation. We find that there exists an optimal confinement for migration. We provide numerical results as...
Differential CYP 2D6 metabolism alters primaquine pharmacokinetics.
Potter, Brittney M J; Xie, Lisa H; Vuong, Chau; Zhang, Jing; Zhang, Ping; Duan, Dehui; Luong, Thu-Lan T; Bandara Herath, H M T; Dhammika Nanayakkara, N P; Tekwani, Babu L; Walker, Larry A; Nolan, Christina K; Sciotti, Richard J; Zottig, Victor E; Smith, Philip L; Paris, Robert M; Read, Lisa T; Li, Qigui; Pybus, Brandon S; Sousa, Jason C; Reichard, Gregory A; Marcsisin, Sean R
2015-04-01
Primaquine (PQ) metabolism by the cytochrome P450 (CYP) 2D family of enzymes is required for antimalarial activity in both humans (2D6) and mice (2D). Human CYP 2D6 is highly polymorphic, and decreased CYP 2D6 enzyme activity has been linked to decreased PQ antimalarial activity. Despite the importance of CYP 2D metabolism in PQ efficacy, the exact role that these enzymes play in PQ metabolism and pharmacokinetics has not been extensively studied in vivo. In this study, a series of PQ pharmacokinetic experiments were conducted in mice with differential CYP 2D metabolism characteristics, including wild-type (WT), CYP 2D knockout (KO), and humanized CYP 2D6 (KO/knock-in [KO/KI]) mice. Plasma and liver pharmacokinetic profiles from a single PQ dose (20 mg/kg of body weight) differed significantly among the strains for PQ and carboxy-PQ. Additionally, due to the suspected role of phenolic metabolites in PQ efficacy, these were probed using reference standards. Levels of phenolic metabolites were highest in mice capable of metabolizing CYP 2D6 substrates (WT and KO/KI 2D6 mice). PQ phenolic metabolites were present in different quantities in the two strains, illustrating species-specific differences in PQ metabolism between the human and mouse enzymes. Taking the data together, this report furthers understanding of PQ pharmacokinetics in the context of differential CYP 2D metabolism and has important implications for PQ administration in humans with different levels of CYP 2D6 enzyme activity. PMID:25645856
H. Stachel, Professor A Way to Geometry Through Descriptive Geometry
Stachel, Hellmuth
motions in [9]. The correspondence be- tween non-Euclidean differential geometry and the geometryH. Stachel, Professor A Way to Geometry Through Descriptive Geometry Vienna University of geometry and on my contributions to Descriptive Geometry education. Descriptive Geometry in Austria
Differential Cytochrome P450 2D Metabolism Alters Tafenoquine Pharmacokinetics.
Vuong, Chau; Xie, Lisa H; Potter, Brittney M J; Zhang, Jing; Zhang, Ping; Duan, Dehui; Nolan, Christina K; Sciotti, Richard J; Zottig, Victor E; Nanayakkara, N P Dhammika; Tekwani, Babu L; Walker, Larry A; Smith, Philip L; Paris, Robert M; Read, Lisa T; Li, Qigui; Pybus, Brandon S; Sousa, Jason C; Reichard, Gregory A; Smith, Bryan; Marcsisin, Sean R
2015-07-01
Cytochrome P450 (CYP) 2D metabolism is required for the liver-stage antimalarial efficacy of the 8-aminoquinoline molecule tafenoquine in mice. This could be problematic for Plasmodium vivax radical cure, as the human CYP 2D ortholog (2D6) is highly polymorphic. Diminished CYP 2D6 enzyme activity, as in the poor-metabolizer phenotype, could compromise radical curative efficacy in humans. Despite the importance of CYP 2D metabolism for tafenoquine liver-stage efficacy, the exact role that CYP 2D metabolism plays in the metabolism and pharmacokinetics of tafenoquine and other 8-aminoquinoline molecules has not been extensively studied. In this study, a series of tafenoquine pharmacokinetic experiments were conducted in mice with different CYP 2D metabolism statuses, including wild-type (WT) (reflecting extensive metabolizers for CYP 2D6 substrates) and CYPmouse 2D knockout (KO) (reflecting poor metabolizers for CYP 2D6 substrates) mice. Plasma and liver pharmacokinetic profiles from a single 20-mg/kg of body weight dose of tafenoquine differed between the strains; however, the differences were less striking than previous results obtained for primaquine in the same model. Additionally, the presence of a 5,6-ortho-quinone tafenoquine metabolite was examined in both mouse strains. The 5,6-ortho-quinone species of tafenoquine was observed, and concentrations of the metabolite were highest in the WT extensive-metabolizer phenotype. Altogether, this study indicates that CYP 2D metabolism in mice affects tafenoquine pharmacokinetics and could have implications for human tafenoquine pharmacokinetics in polymorphic CYP 2D6 human populations. PMID:25870069
Update on 2-D array transducers for medical ultrasound
Stephen W. Smith; Richard E. Davidsen; Charles D. Emery; Richard L. Goldberg; Edward D. Light
1995-01-01
l˝-D and 2-D arrays offer a myriad of new imaging modalities and benefits when compared to the linear array. However, with added benefits come many problems and challenges and l˝-D and 2-D arrays are no exception. The authors give possible solutions to a number of these challenges. The increase in transducer channels needed in a 1˝-D and 2-D array can
Water Quality Additions to CASC2D - TAPS
Patrick N. Deliman; Terry K. Gerald; Carlos E. Ruiz
PURPOSE: The purpose of this effort was the implementation of nutrient water quality compo- nents included in the Transport and Pollutant System (TAPS) into the CASC2D hydrology water- shed model. The CASC2D model is still in development and is being improved, refined, and updated with new technology. Users of CASC2D need to have a thorough background in hydrology and nu-
Jamming and flow statistics in a silo geometry
A. Martin; F. Dubois; Y. Monerie; F. Radjai
2009-01-01
We propose a 2D study of jamming at the outlet of a silo in the metastable state by means of the nonsmooth contact dynamics method. The jamming problem in this geometry can be mapped into the avalanche problem on a granular slope. In this analogy, the size of the opening plays the same role as the slope angle whereas the
Communication: Determining the lowest-energy isomer of Au8: 2D, or not 2D.
Hansen, Jared A; Piecuch, Piotr; Levine, Benjamin G
2013-09-01
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 Mřller-Plesset perturbation theory calculations. The highest-level computations, in which the single-point CCSD(T) calculations employing the correlation-consistent basis set of the cc-pVTZ quality and the associated relativistic effective core potential (ECP), both optimized for gold, and correlating the 5d(10)6s(1) valence and 5s(2)5p(6) semi-core electrons, are combined with the geometrical information obtained with the corresponding CCSD(T)/cc-pVDZ/ECP approach, favor the planar configuration, with the next three non-planar structures separated by 4-6 kcal/mol. In agreement with the earlier work, smaller-basis set CCSD(T) computations provide unreliable results for the relative energetics, even when the geometries are optimized at the CCSD(T) level. PMID:24028093
Communication: Determining the lowest-energy isomer of Au8: 2D, or not 2D
NASA Astrophysics Data System (ADS)
Hansen, Jared A.; Piecuch, Piotr; Levine, Benjamin G.
2013-09-01
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 Mřller-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.
Digital Geometry Tools and Algorithms http://liris.cnrs.fr/dgtal
Lévy, Bruno
with stream mechanism · 3D viewer with stream mechanism based on QGLviewer (New in 0.3) · image, volumes): contours, 3D viewer · Tristan Roussillon (LIRIS): 2D geometry · Guillaume Damiand (LIRIS): kernel · SDigital Geometry Tools and Algorithms http://liris.cnrs.fr/dgtal LORIA 6-8 avril 2011 1 DGtal
John Stillwell
\\u000a Surprisingly, the geometry of curved surfaces throws light on the geometry of the plane. More than 2000 years after Euclid\\u000a formulated axioms for plane geometry, differential geometry showed that the parallel axiom does not follow from the other axioms of Euclid. It had long been hoped that the parallel axiom followed from the others, but no proof had ever been
Functional characterization of CYP2D6 enhancer polymorphisms.
Wang, Danxin; Papp, Audrey C; Sun, Xiaochun
2015-03-15
CYP2D6 metabolizes nearly 25% of clinically used drugs. Genetic polymorphisms cause large inter-individual variability in CYP2D6 enzyme activity and are currently used as biomarker to predict CYP2D6 metabolizer phenotype. Previously, we had identified a region 115 kb downstream of CYP2D6 as enhancer for CYP2D6, containing two completely linked single nucleotide polymorphisms (SNPs), rs133333 and rs5758550, associated with enhanced transcription. However, the enhancer effect on CYP2D6 expression, and the causative variant, remained to be ascertained. To characterize the CYP2D6 enhancer element, we applied chromatin conformation capture combined with the next-generation sequencing (4C assays) and chromatin immunoprecipitation with P300 antibody, in HepG2 and human primary culture hepatocytes. The results confirmed the role of the previously identified enhancer region in CYP2D6 expression, expanding the number of candidate variants to three highly linked SNPs (rs133333, rs5758550 and rs4822082). Among these, only rs5758550 demonstrated regulating enhancer activity in a reporter gene assay. Use of clustered regularly interspaced short palindromic repeats mediated genome editing in HepG2 cells targeting suspected enhancer regions decreased CYP2D6 mRNA expression by 70%, only upon deletion of the rs5758550 region. These results demonstrate robust effects of both the enhancer element and SNP rs5758550 on CYP2D6 expression, supporting consideration of rs5758550 for CYP2D6 genotyping panels to yield more accurate phenotype prediction. PMID:25381333
NSDL National Science Digital Library
Levy, Silvio
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.
NASA Astrophysics Data System (ADS)
Chae, Dongho; Constantin, Peter; Wu, Jiahong
2014-09-01
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.
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
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.
3-D Ray-tracing and 2-D Fokker-Planck simulations of radiofrequency application to tokamak plasmas
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
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.
Assessing plasma filling in NIF cluster geometry
NASA Astrophysics Data System (ADS)
McAlpin, S. W.; Stevenson, R. M.; Thomas, B. R.; Kline, J.; Batha, S.
2006-06-01
The National Ignition Facility (NIF), currently under construction at Lawrence Livermore National Laboratory (LLNL) comprises four clusters of 48 laser beams in a symmetric geometry. Each cluster is itself capable of producing potentially useful conditions for hohlraum interaction experiments. The three dimensional nature of the laser illumination geometry in each cluster presents a challenge when modelled with a 2D hydrocode. Recent experiments have been fielded on the OMEGA laser facility to investigate the validity of using such codes in modelling the plasma filling of targets in similar geometries to a NIF cluster. The extent to which plasma filling within hohlraum type targets is a significant issue can potentially be addressed by the observation of laser plasma instabilities, such as Raman backscatter. This can be a significant energy loss mechanism for targets that have electron densities up to quarter critical. Linear Raman gain theory has been applied to the output from AWE's 2D lagrangian radiation hydrodynamics code, NYM, to produce qualitative and quantitative comparisons with these experiments. This provides a basis for judging the fidelity of the approach. \\copyright British Crown Copyright 2005/MOD
Denoising 2-D Vector Fields by Vector Wavelet Thresholding
Westenberg, Michel A.
Denoising 2-D Vector Fields by Vector Wavelet Thresholding Michel A. Westenberg and Thomas Ertl for denoising 2-D vector fields that are corrupted by additive noise. The method is based on the vector wavelet introduce modifications to scalar wavelet coefficient thresholding for dealing with vector
Smoothing 2D model HESS for Kirchhoff migrations Petr Bulant
Cerveny, Vlastislav
Smoothing 2D model HESS for Kirchhoff migrations Petr Bulant Department of Geophysics, Charles and interfaces of the data set 'hess.dat', provided by Amerada Hess, and build the 2D model suitable for ray tracing. 1 Data and model parametrization File 'hess.dat' has the form of a file with input data
Combinatorial structure of rigid transformations in 2D digital images
Paris-Sud XI, Université de
in applications related to 2D or 3D images (e.g., remote sensing, medical imaging). Despite the digital natureCombinatorial structure of rigid transformations in 2D digital images Phuc Ngoa , Yukiko Kenmochia of digital image process- ing applications. When applied on discrete images, rigid transformations
Combinatorial structure of rigid transformations in 2D digital images
Paris-Sud XI, Université de
[1], image registration [2]), and considered in applications related to 2D or 3D images (e.g., remoteCombinatorial structure of rigid transformations in 2D digital images Phuc Ngoa , Yukiko Kenmochia of digital image processing applications. When applied on such discrete images, rigid transformations
Reconstruction of 3-D Figure Motion from 2-D Correspondences
David E. Difranco; Tat-jen Cham; James M. Rehg
2001-01-01
We present a method for computing the 3D motion of articulated models from 2D correspondences. An iterative batch algorithm is proposed which estimates the maximum aposteriori trajectory based on the 2D measurements sub- ject to a number of constraints. These include (i) kinematic constraints based on a 3D kinematic model, (ii) joint an- gle limits, (iii) dynamic smoothing and (iv)
Topology-preserving rigid transformation of 2D digital images
Boyer, Edmond
] or tracking [4]. This concerns not only 3D (e.g., in medical imaging [5]) but also 2D data (e.g., in remote1 Topology-preserving rigid transformation of 2D digital images Phuc Ngo, Nicolas Passat, Yukiko and warping. Index Terms--Digital images, rigid transformation, digital topology, image preprocessing
2D-Shape Analysis Using Conformal Mapping
Eitan Sharon; David Mumford
2004-01-01
The study of 2D shapes and their similarities is a central problem in the field of vision. It arises in particular from the task of classifying and recognizing objects from their observed silhouette. Defining natural distances between 2D shapes cre- ates a metric space of shapes, whose mathematical structure is inherently relevant to the classification task. One intriguing metric space
2D Barcode and Augmented Reality Supported English Learning System
Tsung-yu Liu; Tan-hsu Tan; Yu-ling Chu
2007-01-01
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
Triangulation location fusion algorithm for 2D sensor network
Yu Lei; Xin-xi Feng; Can-bin Zhu; Bin-bin Li
2011-01-01
Problems of estimation and accuracy for target location in two-dimensional (2D) sensor network are investigated. Considering the influence of the actual Earth Curvature on the target location accuracy, a triangulation location with data fusion algorithm based on the actual ellipsoidal earth model for 2D sensor network is presented, and the location equations and accuracy estimation expressions are calculated. The dada
2D Corotational Beam Formulation by Louie L. Yaw
Yaw, Louis L.
words: geometrically nonlinear analysis, 2d corotational beam, variationally consistent, load control in terms of beam elements. As a frame structure is loaded the entire frame deforms from its original1 2D Corotational Beam Formulation by Louie L. Yaw Walla Walla University November 30, 2009 key
Global shape information modelling and classification of 2D workpieces
M. C. WU; J. R. CHEN; S. R. JEN
1994-01-01
This paper presents a representation scheme for modelling the global shape information of 2D workpieces and uses this representation scheme to classify workpieces. The global shape information of a workpiece could be seen as its topological structure. Retrieving workpieces with similar global shape would facilitate some design and manufacturing activities. To derive the proposed representation scheme, a 2D workpiece first
Combinatorial structure of rigid transformations in 2D digital images
Paris-Sud XI, Université de
registration [2]), and considered in applications related to 2D or 3D images (e.g., remote sensing, medicalCombinatorial structure of rigid transformations in 2D digital images Phuc Ngoa , Yukiko Kenmochia of digital image process- ing applications. When applied on discrete images, rigid transformations
Assessment of an ASTER-generated DEM for 2D hydrodynamic flood modeling
NASA Astrophysics Data System (ADS)
Tarekegn, Tesfaye Haimanot; Haile, Alemseged Tamiru; Rientjes, Tom; Reggiani, P.; Alkema, Dinand
2010-12-01
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.
NASA Astrophysics Data System (ADS)
Wang, Zenghui; X-L Feng, Philip
2015-06-01
Black phosphorus (P), a layered material that can be isolated down to individual 2D crystalline sheets, exhibits highly anisotropic mechanical properties due to its corrugated crystal structure in each atomic layer, which are intriguing for two-dimensional (2D) nanomechanical devices. Here we lay the framework for describing the mechanical resonant responses in free-standing black P structures, by using a combination of analytical modeling and numerical simulation. We find that thicker devices (>100 nm) operating in the elastic plate regime exhibit pronounced signatures of mechanical anisotropy, and can lead to new multimode resonant characteristics in terms of mode sequences, shapes, and orientational preferences that are unavailable in nanomechanical resonators made of isotropic materials. In addition, through investigating devices with different geometries, we identify the resonant responses’ dependence on crystal orientation in asymmetric devices, and evaluate the effects from the degree of anisotropy. The results suggest a pathway towards harnessing the mechanical anisotropy in black P for building novel 2D nanomechanical devices and resonant transducers with engineerable multimode functions.
New 2D discrete Fourier transforms in image processing
NASA Astrophysics Data System (ADS)
Grigoryan, Artyom M.; Agaian, Sos S.
2015-03-01
In this paper, the concept of the two-dimensional discrete Fourier transformation (2-D DFT) is defined in the general case, when the form of relation between the spatial-points (x, y) and frequency-points (?1, ?2) is defined in the exponential kernel of the transformation by a nonlinear form L(x, y; ?1, ?2). The traditional concept of the 2-D DFT uses the Diaphanous form x?1 +y?2 and this 2-D DFT is the particular case of the Fourier transform described by the form L(x, y; ?1, ?2). Properties of the general 2-D discrete Fourier transform are described and examples are given. The special case of the N × N-point 2-D Fourier transforms, when N = 2r, r > 1, is analyzed and effective representation of these transforms is proposed. The proposed concept of nonlinear forms can be also applied for other transformations such as Hartley, Hadamard, and cosine transformations.
Theoretical 2D Raman band of strained graphene
NASA Astrophysics Data System (ADS)
Popov, Valentin N.; Lambin, Philippe
2013-04-01
We study the 2D Raman band of in-plane uniaxially strained graphene within a nonorthogonal tight-binding model. At nonzero strain, the obtained 2D band splits into two subbands at strain angles 0? and 30? or into three subbands at intermediate angles. The evolution of the 2D subbands is calculated systematically in the range of the accessible strains from -1% to 3% and for the commonly used laser photon energy from 1.5 to 3.0 eV. The strain rate and dispersion rate of the 2D subbands are derived and tabulated. In particular, these two quantities show large variations up to 50%. The results on the 2D subbands can be used for detecting and monitoring strain in graphene for nanoelectronics applications.
Estrogen-Induced Cholestasis Leads to Repressed CYP2D6 Expression in CYP2D6-Humanized Mice.
Pan, Xian; Jeong, Hyunyoung
2015-07-01
Cholestasis activates bile acid receptor farnesoid X receptor (FXR) and subsequently enhances hepatic expression of small heterodimer partner (SHP). We previously demonstrated that SHP represses the transactivation of cytochrome P450 2D6 (CYP2D6) promoter by hepatocyte nuclear factor (HNF) 4?. In this study, we investigated the effects of estrogen-induced cholestasis on CYP2D6 expression. Estrogen-induced cholestasis occurs in subjects receiving estrogen for contraception or hormone replacement, or in susceptible women during pregnancy. In CYP2D6-humanized transgenic (Tg-CYP2D6) mice, cholestasis triggered by administration of 17?-ethinylestradiol (EE2) at a high dose led to 2- to 3-fold decreases in CYP2D6 expression. This was accompanied by increased hepatic SHP expression and subsequent decreases in the recruitment of HNF4? to CYP2D6 promoter. Interestingly, estrogen-induced cholestasis also led to increased recruitment of estrogen receptor (ER) ?, but not that of FXR, to Shp promoter, suggesting a predominant role of ER? in transcriptional regulation of SHP in estrogen-induced cholestasis. EE2 at a low dose (that does not cause cholestasis) also increased SHP (by ?50%) and decreased CYP2D6 expression (by 1.5-fold) in Tg-CYP2D6 mice, the magnitude of differences being much smaller than that shown in EE2-induced cholestasis. Taken together, our data indicate that EE2-induced cholestasis increases SHP and represses CYP2D6 expression in Tg-CYP2D6 mice in part through ER? transactivation of Shp promoter. PMID:25943116
A community benchmark for viscoplastic thermal convection in a 2-D squared box
NASA Astrophysics Data System (ADS)
Tosi, Nicola; Stein, Claudia; Noack, Lena; Hüttig, Christian; Maierova, Petra; Samuel, Henri; Davies, Rhodri; Wilson, Cian; Kramer, Stephen; Thieulot, Cedric; Glerum, Anne; Fraters, Menno; Rozel, Antoine; Tackley, Paul
2015-04-01
Numerical simulations of thermal convection in the Earth's mantle often employ a pseudo-plastic rheology in order to mimic the plate-like behavior of the lithosphere. Yet the benchmark tests available in the literature are largely based on simple linear rheologies in which the viscosity is either assumed to be constant or weakly dependent on temperature. We present a suite of simple test cases based on non-linear rheologies featuring temperature-, pressure-, and strain-rate dependent viscosity. Eleven different codes based on the finite-volume, finite-element, or spectral method have been used to run five benchmark cases leading to stagnant lid, mobile lid, and periodic convection in a 2-D squared box. For two of these cases, we also show resolution tests from all contributing codes. In addition, we present a bifurcation analysis describing the transition from mobile lid to periodic regime and from periodic to stagnant lid regime in dependence of the yield stress. At a reference resolution of around 100 cells or elements in both vertical and horizontal directions, all codes reproduce the required diagnostic quantities with a discrepancy of at most ~3% in the presence of both linear and non-linear rheologies. Furthermore they all consistently predict the critical value of the yield stress at which the transition between different convective regimes occurs. As the most recent mantle convection codes are capable to handle a number of different domain geometries (2-D and 3-D, rectangular, cylindrical, and spherical) within a single solution framework, this benchmark is expected to be a useful tool to validate simulations of viscoplastic thermal convection also in geometries that are more complex and computationally demanding than a simple 2-D box.
AnisWave2D: User's Guide to the 2d Anisotropic Finite-DifferenceCode
Toomey, Aoife
2005-01-06
This document describes a parallel finite-difference code for modeling wave propagation in 2D, fully anisotropic materials. The code utilizes a mesh refinement scheme to improve computational efficiency. Mesh refinement allows the grid spacing to be tailored to the velocity model, so that fine grid spacing can be used in low velocity zones where the seismic wavelength is short, and coarse grid spacing can be used in zones with higher material velocities. Over-sampling of the seismic wavefield in high velocity zones is therefore avoided. The code has been implemented to run in parallel over multiple processors and allows large-scale models and models with large velocity contrasts to be simulated with ease.
Tory, Melanie
Comparing a single 2D scatter plot, a single 3D scatter plot with Motion, and a 2D SPLOM Supervisory Committee Comparing a single 2D scatter plot, a single 3D scatter plot with Motion, and a 2D SPLOM ............................................................................................................................4 2.1 Comparing 2D and 3D displays
NKG2D CAR T cell therapy inhibits the growth of NKG2D ligand heterogeneous tumors
Spear, Paul; Barber, Amorette; Rynda-Apple, Agnieszka; Sentman, Charles L.
2013-01-01
Tumor heterogeneity presents a substantial barrier to increasing clinical responses mediated by targeted therapies. Broadening the immune response elicited by treatments that target a single antigen is necessary for the elimination of tumor variants that fail to express the targeted antigen. In this study, it is shown that adoptive transfer of T cells bearing a chimeric antigen receptor (CAR) inhibited the growth of target-expressing and –deficient tumor cells within ovarian and lymphoma tumors. Mice bearing the ID8 ovarian or RMA lymphoma tumors were treated with T cells transduced with a NKG2D-based CAR (chNKG2D). NKG2D CAR T cell therapy protected mice from heterogeneous RMA tumors. Moreover, adoptive transfer of chNKG2D T cells mediated tumor protection against highly heterogeneous ovarian tumors in which 50%, 20%, or only 7% of tumor cells expressed significant amounts of NKG2D ligands. CAR T cells did not mediate an in vivo response against tumor cells that did not express sufficient amounts of NKG2D ligands, and the number of ligand-expressing tumor cells correlated with therapeutic efficacy. In addition, tumor-free surviving mice were protected against a tumor re-challenge with NKG2D ligand-negative ovarian tumor cells. These data indicate that NKG2D CAR T cell treatment can be an effective therapy against heterogeneous tumors and induce tumor-specific immunity against ligand-deficient tumor cells. PMID:23628805
Efficient 2D MRI relaxometry using compressed sensing.
Bai, Ruiliang; Cloninger, Alexander; Czaja, Wojciech; Basser, Peter J
2015-06-01
Potential applications of 2D relaxation spectrum NMR and MRI to characterize complex water dynamics (e.g., compartmental exchange) in biology and other disciplines have increased in recent years. However, the large amount of data and long MR acquisition times required for conventional 2D MR relaxometry limits its applicability for in vivo preclinical and clinical MRI. We present a new MR pipeline for 2D relaxometry that incorporates compressed sensing (CS) as a means to vastly reduce the amount of 2D relaxation data needed for material and tissue characterization without compromising data quality. Unlike the conventional CS reconstruction in the Fourier space (k-space), the proposed CS algorithm is directly applied onto the Laplace space (the joint 2D relaxation data) without compressing k-space to reduce the amount of data required for 2D relaxation spectra. This framework is validated using synthetic data, with NMR data acquired in a well-characterized urea/water phantom, and on fixed porcine spinal cord tissue. The quality of the CS-reconstructed spectra was comparable to that of the conventional 2D relaxation spectra, as assessed using global correlation, local contrast between peaks, peak amplitude and relaxation parameters, etc. This result brings this important type of contrast closer to being realized in preclinical, clinical, and other applications. PMID:25917134
Efficient 2D MRI relaxometry using compressed sensing
NASA Astrophysics Data System (ADS)
Bai, Ruiliang; Cloninger, Alexander; Czaja, Wojciech; Basser, Peter J.
2015-06-01
Potential applications of 2D relaxation spectrum NMR and MRI to characterize complex water dynamics (e.g., compartmental exchange) in biology and other disciplines have increased in recent years. However, the large amount of data and long MR acquisition times required for conventional 2D MR relaxometry limits its applicability for in vivo preclinical and clinical MRI. We present a new MR pipeline for 2D relaxometry that incorporates compressed sensing (CS) as a means to vastly reduce the amount of 2D relaxation data needed for material and tissue characterization without compromising data quality. Unlike the conventional CS reconstruction in the Fourier space (k-space), the proposed CS algorithm is directly applied onto the Laplace space (the joint 2D relaxation data) without compressing k-space to reduce the amount of data required for 2D relaxation spectra. This framework is validated using synthetic data, with NMR data acquired in a well-characterized urea/water phantom, and on fixed porcine spinal cord tissue. The quality of the CS-reconstructed spectra was comparable to that of the conventional 2D relaxation spectra, as assessed using global correlation, local contrast between peaks, peak amplitude and relaxation parameters, etc. This result brings this important type of contrast closer to being realized in preclinical, clinical, and other applications.
Turbulent flow over a surface-mounted 2-D block in thermally-stratified boundary layers
NASA Astrophysics Data System (ADS)
Zhang, W.; Markfort, C. D.; Porte-Agel, F.
2013-12-01
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.
Geometry of thin nematic elastomer sheets.
Aharoni, Hillel; Sharon, Eran; Kupferman, Raz
2014-12-19
A thin sheet of nematic elastomer attains 3D configurations depending on the nematic director field upon heating. In this Letter, we describe the intrinsic geometry of such a sheet and derive an expression for the metric induced by general nematic director fields. Furthermore, we investigate the reverse problem of constructing a director field that induces a specified 2D geometry. We provide an explicit recipe for how to construct any surface of revolution using this method. Finally, we show that by inscribing a director field gradient across the sheet's thickness, one can obtain a nontrivial hyperbolic reference curvature tensor, which together with the prescription of a reference metric allows dictation of actual configurations for a thin sheet of nematic elastomer. PMID:25554907
Developments in special geometry
Thomas Mohaupt; Owen Vaughan
2012-01-19
We review the special geometry of N = 2 supersymmetric vector and hypermultiplets with emphasis on recent developments and applications. A new formulation of the local c-map based on the Hesse potential and special real coordinates is presented. Other recent developments include the Euclidean version of special geometry, and generalizations of special geometry to non-supersymmetric theories. As applications we disucss the proof that the local r-map and c-map preserve geodesic completeness, and the construction of four- and five-dimensional static solutions through dimensional reduction over time. The shared features of the real, complex and quaternionic version of special geometry are stressed throughout.
Developments in special geometry
Mohaupt, Thomas
2011-01-01
We review the special geometry of N = 2 supersymmetric vector and hypermultiplets with emphasis on recent developments and applications. A new formulation of the local c-map based on the Hesse potential and special real coordinates is presented. Other recent developments include the Euclidean version of special geometry, and generalizations of special geometry to non-supersymmetric theories. As applications we disucss the proof that the local r-map and c-map preserve geodesic completeness, and the construction of four- and five-dimensional static solutions through dimensional reduction over time. The shared features of the real, complex and quaternionic version of special geometry are stressed throughout.
Conformal field theory of critical Casimir interactions in 2D
Bimonte, G.
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 ...
Technical Review of the UNET2D Hydraulic Model
Perkins, William A.; Richmond, Marshall C.
2009-05-18
The Kansas City District of the US Army Corps of Engineers is engaged in a broad range of river management projects that require knowledge of spatially-varied hydraulic conditions such as velocities and water surface elevations. This information is needed to design new structures, improve existing operations, and assess aquatic habitat. Two-dimensional (2D) depth-averaged numerical hydraulic models are a common tool that can be used to provide velocity and depth information. Kansas City District is currently using a speci?c 2D model, UNET2D, that has been developed to meet the needs of their river engineering applications. This report documents a tech- nical review of UNET2D.
STOCHASTIC 2-D NAVIER-STOKES EQUATION WITH ARTIFICIAL COMPRESSIBILITY
Menaldi, Jose-Luis
STOCHASTIC 2-D NAVIER-STOKES EQUATION WITH ARTIFICIAL COMPRESSIBILITY Navier-Stokes equation wi* *th artificial compressibility. The main results of this work of the deterministic Navier- Stokes equation with artificial compressibility in bounded domains. In the rest
Conductivity of 2D polycrystalline media in a magnetic field
Dykhne, A. M. [Russian State Research Center Troitsk Institute for Innovation and Thermonuclear Research (Russian Federation); Snarskii, A. A. [Ukrainian National Technical University, Kiev Polytechnical Institute (Ukraine)], E-mail: asnar@phys.carrier.kiev.ua
2006-03-15
The effective conductivity of 2D polycrystalline media in a magnetic field is considered. A current trap model constructed for strongly anisotropic polycrystalline media makes it possible to determine the distribution of the Joule heat liberated in such media.
Scheduling and 2D placement heuristics for partially reconfigurable systems
Santambrogio, Marco Domenico
This paper proposes new scheduling and 2D placement heuristics for partially dynamically reconfigurable systems. One specific focus of this work is to deal with applications containing hundreds of tasks grouped in a few ...
From weakly to strongly interacting 2D Fermi gases
NASA Astrophysics Data System (ADS)
Dyke, Paul; Fenech, Kristian; Lingham, Marcus; Peppler, Tyson; Hoinka, Sascha; Vale, Chris
2014-05-01
We study ultracold 2D Fermi gases of 6Li formed in a highly oblate trapping potential. The potential is generated by a cylindrically focused, blue detuned TEM01 mode laser beam. Weak magnetic field curvature provides highly harmonic confinement in the radial direction and we can readily produce single clouds with an aspect ratio of 230. Our experiments investigate the dimensional crossover from 3D to 2D for a two component Fermi gas in the Bose-Einstein Condensate to Bardeen Cooper Schrieffer crossover. Observation of an elbow in measurements of the cloud width vs. atom number is consistent with populating only the lowest transverse harmonic oscillator state for weak attractive interactions. This measurement is extended to the strongly interacting region using the broad Feshbach resonance at 832 G. We also report our progress towards measurement of the 2D equation of state for an interacting 2D Fermi gas via in-situ absorption imaging.
On a Mean Field Theory of Topological 2D Gravity
Jian Zhou
2015-03-30
We present a one-dimensional mean field theory for topological 2D gravity. We discuss possible generalizations to other topological field theories, in particular those related to semisimple Frobenius manifolds.
2. D Street facade and rear (east) blank wall of ...
2. D Street facade and rear (east) blank wall of parking garage. Farther east is 408 8th Street (National Art And Frame Company). - PMI Parking Garage, 403-407 Ninth Street, Northwest, Washington, District of Columbia, DC
2D TEM-MODE THz QUASIOPTICS STEVEN M. COLEMAN
Oklahoma State University
2D TEM-MODE THz QUASIOPTICS By STEVEN M. COLEMAN Bachelor of Science Oklahoma State University ________________________________________________ Dissertation Advisor R. Alan Cheville ________________________________________________ James C. West ________________________________________________ James P. Wicksted ________________________________________________ A. Gordon Emslie
Van der Waals heterostructures: Stacked 2D materials shed light
NASA Astrophysics Data System (ADS)
Wang, Xiaomu; Xia, Fengnian
2015-03-01
A powerful strategy to leverage and combine the optoelectronic characteristics of different 2D materials is to stack them into vertical van der Waals heterostructures. This approach is now used to realize efficient light-emitting devices.
A 2d spray model with gyroscopic effects. Ayman Moussa
Sueur, Franck
A 2d spray model with gyroscopic effects. Ayman Moussa , Franck Sueur , December 15, 2011 Abstract-type equation and an Euler-type equation: the fluid acts on the dispersed phase through a gyroscopic force
Implementation of 2D\\/3D Transformation for Clothing Panel
Xinrong Hu; Yan Bai; Shuqin Cui; Zhongmin Deng
2009-01-01
2D\\/3D transformation for clothing panel is one of most important steps for virtual clothing. And vector mesh generation is one of the basic tasks that complete 2D\\/3D transformation of clothing panel images and virtual clothing designs. Based on the classical methods of generating meshes, an algorithm for generating vector meshes which is suitable for garment panel images was presented. The
On computing the 2-D extended lapped transforms
D. Sevic; M. Popovic
1997-01-01
A new implementation of the two-dimensional extended lapped transform (2-D ELT) is proposed. Compared to the separable solution, proposed by Malvar (1992), the new realization of the 2-D ELT has a reduced arithmetic complexity. Computational savings are achieved because scaling and inverse scaling of the butterfly matrices, suggested by Malvar for the 1-D case, are, after some modifications of the
Compression of 2-D Biomedical Images 7.1. Introduction
Paris-Sud XI, Université de
) or even spatio-temporal sequences (i.e. 3D+t) by encoding each image separately and independently of all of medical images are acquired using 2D acquisition imaging systems (e.g., vertebra and lung digital X rays, mammography). Moreover, it is possible to compress temporal sequences (i.e. 2D+t), volume sequences (i.e. 3D
A vision-based 2D-3D registration system
Quan Wang; Suya You
2009-01-01
In this paper, we propose an automatic system for robust alignment of 2D optical images with 3D LiDAR (light detection and ranging) data. Focusing on applications such as data fusion and rapid updating for GIS (geographic information systems) from diverse sources when accurate georeference is not available, our goal is a vision-based approach to recover the 2D to 3D transformation
Real-time 2D to 3D video conversion
Ianir A. Ideses; Leonid P. Yaroslavsky; Barak Fishbain
2007-01-01
We present a real-time implementation of 2D to 3D video conversion using compressed video. In our method, compressed 2D video\\u000a is analyzed by extracting motion vectors. Using the motion vector maps, depth maps are built for each frame and the frames\\u000a are segmented to provide object-wise depth ordering. These data are then used to synthesize stereo pairs. 3D video synthesized
Volumetric Elasticity Imaging with a 2-D CMUT Array
Ted G. Fisher; Timothy J. Hall; Satchi Panda; Michael S. Richards; Paul E. Barbone; Jingfeng Jiang; Jeff Resnick; Steve Barnes
2010-01-01
This article reports the use of a two-dimensional (2-D) capacitive micro-machined ultrasound transducer (CMUT) to acquire radio-frequency (RF) echo data from relatively large volumes of a simple ultrasound phantom to compare three-dimensional (3-D) elasticity imaging methods. Typical 2-D motion tracking for elasticity image formation was compared with three different methods of 3-D motion tracking, with sum-squared difference (SSD) used as
Integrating TITAN2D Geophysical Mass Flow Model with GIS
L. M. Namikawa; C. Renschler
2005-01-01
TITAN2D simulates geophysical mass flows over natural terrain using depth-averaged granular flow models and requires spatially distributed parameter values to solve differential equations. Since a Geographical Information System (GIS) main task is integration and manipulation of data covering a geographic region, the use of a GIS for implementation of simulation of complex, physically-based models such as TITAN2D seems a natural
Imperfect 2D phosphorus, yet an almost perfect semiconductor
NASA Astrophysics Data System (ADS)
Penev, Evgeni; Liu, Yuanyue; Xu, Fangbo; Zhang, Ziang; Yakobson, Boris
2015-03-01
The deep gap states created by defects in semiconductors typically deteriorate the performance of (opto)electronic devices. This has limited the applications of two-dimensional (2D) metal dichalcogenides (MX2) and underscored the need for a new 2D semiconductor without defect-induced deep gap states. The talk will discuss why a 2D mono-elemental semiconductor can be a promising candidate. This is exemplified by a first-principles study of 2D phosphorus (``phosphorene''), a recently fabricated high-mobility semiconductor. Most of the defects, including intrinsic point defects and grain boundaries, are electronically inactive, thanks to the homoelemental bonding, which is not preferred in heteroelemental system such as MX2. Unlike MX2, where the edges create deep gap states and cannot be eliminated by passivation, the edge states of 2D P can be removed from the band gap by hydrogen termination. It is further found that both the type and the concentration of charge carriers in 2D P can be tuned by doping with foreign atoms. The work sheds light on the role of defects on the electronic structure of low-dimensional materials in general. Present affiliation: NREL
Geometry Here, Geometry There, Geomerty is EVERYWHERE!
NSDL National Science Digital Library
Miss Tiller
2012-02-05
See if you know your geometry by using coordinate planes! GAME 1 Space Boy To The Rescue! See if you can fly through space using coordinate pairs if you dare! Directions: Double click on the space astronaut on the right hand side of the screen. Your astronaut should ...
Some links between turtle geometry and analytic geometry
Neil C. Rowe
1985-01-01
The computer language LOGO facilitates the teaching of analytic geometry and calculus from the notion of curvature, through its ‘turtle geometry’ facility [2]. We provide some theoretical basis for finding turtle geometry equivalents of familiar curves in analytic geometry, and vice versa, by some simple methods which apparently have not been noticed previously. In particular, we study turtle geometry programs
Sensitivity analysis of imaging geometries for prostate diffuse optical tomography
Zhou, Xiaodong; Zhu, Timothy C.
2015-01-01
Endoscopic and interstitial diffuse optical tomography have been studied in clinical investigations for imaging prostate tissues, yet, there is no comprehensive comparison of how these two imaging geometries affect the quality of the reconstruction images. In this study, the effect of imaging geometry is investigated by comparing the cross-section of the Jacobian sensitivity matrix and reconstructed images for three-dimensional mathematical phantoms. Next, the effect of source-detector configurations and number of measurements in both geometries is evaluated using singular value analysis. The amount of information contained for each source-detector configuration and different number of measurements are compared. Further, the effect of different measurements strategies for 3D endoscopic and interstitial tomography is examined. The pros and cons of using the in-plane measurements and off-plane measurements are discussed. Results showed that the reconstruction in the interstitial geometry outperforms the endoscopic geometry when deeper anomalies are present. Eight sources 8 detectors and 6 sources 12 detectors are sufficient for 2D reconstruction with endoscopic and interstitial geometry respectively. For a 3D problem, the quantitative accuracy in the interstitial geometry is significantly improved using off-plane measurements but only slightly in the endoscopic geometry.
Euclidean Geometry via Programming.
ERIC Educational Resources Information Center
Filimonov, Rossen; Kreith, Kurt
1992-01-01
Describes the Plane Geometry System computer software developed at the Educational Computer Systems laboratory in Sofia, Bulgaria. The system enables students to use the concept of "algorithm" to correspond to the process of "deductive proof" in the development of plane geometry. Provides an example of the software's capability and compares it to…
ERIC Educational Resources Information Center
Lyublinskaya, Irina; Funsch, Dan
2012-01-01
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…
2D whispering gallery vs. 3D whispering cave
NASA Astrophysics Data System (ADS)
Kwon, O'Dae
2008-02-01
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.
Geometrie im Internet Wolfgang Rath
Stachel, Hellmuth
Geometrie im Internet Wolfgang Rath Institut für Geometrie, TU Wien rath@geometrie.tuwien.ac.at http://www.geometrie.tuwien.ac.at/rath Version 1999-11-15 #12;Geometrie im Internet - Wolfgang Rath......................................................................................... 5 1.1 SCHNELLER EINSTIEG INS INTERNET
Geometries for CAGD Helmut Pottmanna
Nawratil, Georg
, and non-Euclidean geometries. In all cases, we outline and illustrate applications of the respective modeling and addresses Euclidean, affine and projective geometry, as well as differential geometry in Projective Geometry Differential geometry in projective spaces requires some modifications over Euclidean
Flavors of Geometry MSRI Publications
Kapovich, Misha
of non-Euclidean geometry, that is, a geometry that discards one of Euclid's axioms. Einstein and Minkowski found in non-Euclidean geometry a This work was supported in part by The Geometry Center of the twentieth century every serious student of mathematics and physics studied non-Euclidean geometry. This has
Resistivity of dilute 2D electrons in an undoped GaAs heterostructure.
Lilly, M P; Reno, J L; Simmons, J A; Spielman, I B; Eisenstein, J P; Pfeiffer, L N; West, K W; Hwang, E H; Das Sarma, S
2003-02-01
We report resistivity measurements from 0.03 to 10 K in a dilute high mobility 2D electron system. Using an undoped GaAs/AlGaAs heterojunction in a gated field-effect transistor geometry, a wide range of densities, 0.16 x 10(10) to 7.5 x 10(10) cm(-2), are explored. For high densities, the results are quantitatively shown to be due to scattering by acoustic phonons and impurities. In an intermediate range of densities, a peak in the resistivity is observed for temperatures below 1 K. This nonmonotonic resistivity can be understood by considering the known scattering mechanisms of phonons, bulk, and interface ionized impurities. Still lower densities appear insulating to the lowest temperature measured. PMID:12633388
The role of the Beltrami parametrization of complex structures in 2-d Free Conformal Field Theory
Serge Lazzarini
2005-09-30
This talk gives a review on how complex geometry and a Lagrangian formulation of 2-d conformal field theory are deeply related. In particular, how the use of the Beltrami parametrization of complex structures on a compact Riemann surface fits perfectly with the celebrated locality principle of field theory, the latter requiring the use infinite dimensional spaces. It also allows a direct application of the local index theorem for families of elliptic operators due to J.-M. Bismut, H. Gillet and C. Soul\\'{e}. The link between determinant line bundles equipped with the Quillen\\'s metric and the so-called holomorphic factorization property will be addressed in the case of free spin $j$ b-c systems or more generally of free fields with values sections of a holomorphic vector bundles over a compact Riemann surface.
Toward an Efficient Icing CFD Process Using an Interactive Software Toolkit--SmaggIce 2D
NASA Technical Reports Server (NTRS)
Vickerman, Mary B.; Choo, Yung K.; Schilling, Herbert W.; Baez, Marivell; Braun, Donald C.; Cotton, Barbara J.
2002-01-01
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.
Amoeboid motion in confined geometry
Hao Wu; Marine Thiébaut; Wei-Fan Hu; Alexander Farutin; Salima Rafaď; Ming-Chih Lai; Philippe Peyla; Chaouqi Misbah
2015-02-13
Cells of the immune system, as well as cancer cells, migrating in confined environment of tissues undergo frequent shape changes (described as amoeboid motion) that enable them to move forward through these porous media without the assistance of adhesion sites. In other words, they perform amoeboid swimming (AS) while using extracellular matrices and cells of tissues as support. We introduce a simple model of AS in a confined geometry solved by means of 2D numerical simulations. We find that confinement promotes AS, unless being so strong that it restricts shape change amplitude. A straight AS trajectory in the channel is found to be unstable, and ample lateral excursions of the swimmer prevail. For weak confinement, these excursions are symmetric, while they become asymmetric at stronger confinement, whereby the swimmer is located closer to one of the two walls. This is a spontaneous symmetry-breaking bifurcation. We find that there exists an optimal confinement for migration. We provide numerical results as well as scaling laws. This study raises the question of the relevance of these scenarios to complex situations encountered in vivo.
Ultrafast 2D-IR spectroelectrochemistry of flavin mononucleotide
NASA Astrophysics Data System (ADS)
El Khoury, Youssef; Van Wilderen, Luuk J. G. W.; Bredenbeck, Jens
2015-06-01
We demonstrate the coupling of ultrafast two-dimensional infrared (2D-IR) spectroscopy to electrochemistry in solution and apply it to flavin mononucleotide, an important cofactor of redox proteins. For this purpose, we designed a spectroelectrochemical cell optimized for 2D-IR measurements in reflection and measured the time-dependent 2D-IR spectra of the oxidized and reduced forms of flavin mononucleotide. The data show anharmonic coupling and vibrational energy transfer between different vibrational modes in the two redox species. Such information is inaccessible with redox-controlled steady-state FTIR spectroscopy. The wide range of applications offered by 2D-IR spectroscopy, such as sub-picosecond structure determination, IR band assignment via energy transfer, disentangling reaction mixtures through band connectivity in the 2D spectra, and the measurement of solvation dynamics and chemical exchange can now be explored under controlled redox potential. The development of this technique furthermore opens new horizons for studying the dynamics of redox proteins.
Ultrafast 2D-IR spectroelectrochemistry of flavin mononucleotide.
El Khoury, Youssef; Van Wilderen, Luuk J G W; Bredenbeck, Jens
2015-06-01
We demonstrate the coupling of ultrafast two-dimensional infrared (2D-IR) spectroscopy to electrochemistry in solution and apply it to flavin mononucleotide, an important cofactor of redox proteins. For this purpose, we designed a spectroelectrochemical cell optimized for 2D-IR measurements in reflection and measured the time-dependent 2D-IR spectra of the oxidized and reduced forms of flavin mononucleotide. The data show anharmonic coupling and vibrational energy transfer between different vibrational modes in the two redox species. Such information is inaccessible with redox-controlled steady-state FTIR spectroscopy. The wide range of applications offered by 2D-IR spectroscopy, such as sub-picosecond structure determination, IR band assignment via energy transfer, disentangling reaction mixtures through band connectivity in the 2D spectra, and the measurement of solvation dynamics and chemical exchange can now be explored under controlled redox potential. The development of this technique furthermore opens new horizons for studying the dynamics of redox proteins. PMID:26049436
ARC2D - EFFICIENT SOLUTION METHODS FOR THE NAVIER-STOKES EQUATIONS (CRAY VERSION)
NASA Technical Reports Server (NTRS)
Pulliam, T. H.
1994-01-01
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.
ARC2D - EFFICIENT SOLUTION METHODS FOR THE NAVIER-STOKES EQUATIONS (DEC RISC ULTRIX VERSION)
NASA Technical Reports Server (NTRS)
Biyabani, S. R.
1994-01-01
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.
SmaggIce 2D Version 1.8: Software Toolkit Developed for Aerodynamic Simulation Over Iced Airfoils
NASA Technical Reports Server (NTRS)
Choo, Yung K.; Vickerman, Mary B.
2005-01-01
SmaggIce 2D version 1.8 is a software toolkit developed at the NASA Glenn Research Center that consists of tools for modeling the geometry of and generating the grids for clean and iced airfoils. Plans call for the completed SmaggIce 2D version 2.0 to streamline the entire aerodynamic simulation process--the characterization and modeling of ice shapes, grid generation, and flow simulation--and to be closely coupled with the public-domain application flow solver, WIND. Grid generated using version 1.8, however, can be used by other flow solvers. SmaggIce 2D will help researchers and engineers study the effects of ice accretion on airfoil performance, which is difficult to do with existing software tools because of complex ice shapes. Using SmaggIce 2D, when fully developed, to simulate flow over an iced airfoil will help to reduce the cost of performing flight and wind-tunnel tests for certifying aircraft in natural and simulated icing conditions.
NSDL National Science Digital Library
2007-12-12
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)
Double Brillouin scattering geometry
NASA Astrophysics Data System (ADS)
Mroz, B.; Mielcarek, S.
2001-02-01
A procedure to optimize the collection of Brillouin spectra and to allow the simultaneous observation of phonons in two pairs of scattering geometries is proposed. The first geometry is used to observe the bulk phonons in right-angle- and back-scattering. This procedure reduces measurement time and requires the use of only one type of sample. The second geometry is used for simultaneous observation of bulk and surface phonons in transparent materials and can provide some valuable information on the relation between the bulk and surface elastic properties.
Synthesizing stereo 3D views from focus cues in monoscopic 2D images
NASA Astrophysics Data System (ADS)
Aguirre Valencia, Sergio; Rodriguez-Dagnino, Ramon M.
2003-05-01
In this paper we propose a monoscopic 2D to stereo 3D conversion system. Our process of producing a stereo 3D system from 2D images requires to estimate a relative depth map of the objects in the image that comprises the real world 3D geometry of the scene initially captured. Subsequently, we map the estimated depth into two perspective image views, left and right, with an artificially synthesized parallax between them. We present a depth estimation method based on measuring focus cues, which consists of a local spatial frequency measurement using multiresolution wavelet analysis and a Lipschitz regularity estimation of significant edges; resulting in a pixel resolution depth map. Based on this relative depth map, the stereo 3D image is synthesized with a method that uses interpolated image row sections to artificially generate parallax in the left and right perspective views, and thus when viewed with a stereo 3D display system induce a sense of stereopsis to the observer.
Acoustic Receptivity of a Blasius Boundary Layer with 2-D and Oblique Surface Waviness
NASA Technical Reports Server (NTRS)
King, Rudolph A.; Breuer, Kenneth S.
2000-01-01
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.
Mitri, F G
2015-09-01
The optical theorem for plane waves is recognized as one of the fundamental theorems in optical, acoustical and quantum wave scattering theory as it relates the extinction cross-section to the forward scattering complex amplitude function. Here, the optical theorem is extended and generalized in a cylindrical coordinates system for the case of 2D beams of arbitrary character as opposed to plane waves of infinite extent. The case of scalar monochromatic acoustical wavefronts is considered, and generalized analytical expressions for the extinction, absorption and scattering cross-sections are derived and extended in the framework of the scalar resonance scattering theory. The analysis reveals the presence of an interference scattering cross-section term describing the interaction between the diffracted Franz waves with the resonance elastic waves. The extended optical theorem in cylindrical coordinates is applicable to any object of arbitrary geometry in 2D located arbitrarily in the beam's path. Related investigations in optics, acoustics and quantum mechanics will benefit from this analysis in the context of wave scattering theory and other phenomena closely connected to it, such as the multiple scattering by a cloud of particles, as well as the resulting radiation force and torque. PMID:25773968
Dynamics of 2D Dust Clusters with a Perpendicular Magnetic Field
Greiner, Franko; Carstensen, Jan; Hou Lujing; Piel, Alexander [Institut fuer Experimentelle und Angewandte Physik, Christian-Albrechts Universitaet, Kiel (Germany)
2008-09-07
The physics of two-dimensional (2D) dust clusters in an unmagnetized plasma sheath has been understood in dept. However, introduction of a perpendicular magnetic field into the dusty plasma sheath leads to some new effects, such as rotation and compression of dust clusters, whose mechanism is still unclear. It is found that even for a magnetic field as low as the earth magnetic field ({approx_equal}40 {mu}T), clusters rotate as rigid about their centers. It was proposed [U. Konopka, PRE 61, 1890 (2000)] that the ExB-induced ion flow drives the dust clusters into rotation. Simulations [L.-J. Hou, PoP 12, 042104 (2005)] based on the same hypothesis also reproduced the rotation of 2D clusters in a qualitative manner. However, this model cannot fully explain the experimental observations. We present detailed experimental investigations, which show that the rotation of a dust cluster critically depends on the detailed discharge geometry. In particular, the co-rotation of the background neutral gas and its role in driving dust-cluster rotation is proposed as a mechanism to set the dust cluster in rotation.
NASA Astrophysics Data System (ADS)
Jakubiak, Rachel; Tondiglia, Vincent P.; Natarajan, Lalgudi V.; Lloyd, Pamela F.; Sutherland, Richard; Vaia, Richard A.; Bunning, Timothy J.
2009-02-01
Holographic photopolymerization, such as used to form holographic polymer dispersed liquid crystals (HPDLCs), has the advantage of combining the desirable processing properties of polymers with a periodic distribution of an electrically tunable medium (LC). Herein we describe laser oscillations resulting from distributed feedback in fieldmodulated, 2-D H-PDLC photonic crystals. Compared to results of lasing from pyrromethene 597 in 1-D H-PDLCs, the linewidth of the laser action decreases by at least a factor of four and the lasing wavelength is electrically tunable over 5 nm. The 2-D H-PDLCs consist of LC columns within a polymer matrix that were created by interference of four writing beams on the sample cell. Two configurations were studied; one comprising a reflection grating orthogonal to a transmission grating (in-plane) and the other from two orthogonal transmission gratings (out-of-plane). Given that the lattice spacing was the same for both samples, the lasing wavelengths were similar; however the polarization dependence on lasing threshold varied by a factor of three for the in-plane configuration and electrical switching resulted in bimodal lasing. The out-of-plane geometry showed no polarization dependence on lasing threshold and the lasing blue-shifted with applied electric field.
Engagement of neural circuits underlying 2D spatial navigation in a rodent virtual reality system
Aronov, Dmitriy; Tank, David W.
2015-01-01
SUMMARY Virtual reality (VR) enables precise control of an animal’s environment and otherwise impossible experimental manipulations. Neural activity in navigating rodents has been studied on virtual linear tracks. However, the spatial navigation system’s engagement in complete two-dimensional environments has not been shown. We describe a VR setup for rats, including control software and a large-scale electrophysiology system, which supports 2D navigation by allowing animals to rotate and walk in any direction. The entorhinal-hippocampal circuit, including place cells, grid cells, head direction cells and border cells, showed 2D activity patterns in VR similar to those in the real world. Hippocampal neurons exhibited various remapping responses to changes in the appearance or the shape of the virtual environment, including a novel form in which a VR-induced cue conflict caused remapping to lock to geometry rather than salient cues. These results suggest a general-purpose tool for novel types of experimental manipulations in navigating rats. PMID:25374363
2-D synthetic seismic and log cross sections from stratigraphic forward models
Shuster, M.W. (KSEPL (Shell Research), Rijswijk (Netherlands)); Aigner, T. (Universitat Tubingen (Germany))
1993-09-01
In an effort to fully utilize deterministic stratigraphic forward modeling techniques in subsurface stratigraphic analysis, Shell has developed a computer interface to routinely create synthetic logs and one-dimensional and two-dimensional (2-D) seismic responses from 2-D stratigraphic simulations. Each 2-D stratigraphic model can contain up to 200 timelines defining age equivalent stratigraphic layers with laterally variable lithofacies and depths. Synthetic gamma-ray, density, and velocity responses are calculated for the simulated lithofacies using user-specified rock and fluid properties. Vertically incident synthetic seismograms are created using calculated reflection coefficients and user-defined input wavelets. Because the chronostratigraphy is know a priori, log correlations and the interpolated seismic geometries follow timelines exactly. The power of this technique as an aid in sequence stratigraphic interpretations is shown from three case studies: (1) a simulation of an idealized clastic system assuming constant clastic input and sinusoidal fourth- and third-order sea level variations, (2) simulations of the Permian mixed clastic-carbonate infill of the Midland basin, and (3) a detailed simulation of one third-order carbonate depositional sequence (lower-middle San Andres Formation) from the Northwest Shelf, Permian basin. Some general conclusions form these case studies include the following: (a) seismic and well log-defined topsets, forests, bottom-sets, and related event terminations can be unequivocally related to relative sea level fluctuations; (b) Exxon-type sequence boundaries are not necessarily seismically imageable and their identification on well logs is not straight forward; and (c) buildups and lateral variations in amplitude related to lithofacies variations can be modeled. Synthetic logs and seismic sections from stratigraphic forward models may be useful in constraining interpretations of subsurface data and in stratigraphic prediction.
Turbulent flow over a surface-mounted 2-D block: thermal stability effects
NASA Astrophysics Data System (ADS)
Zhang, Wei; Markfort, Corey; Porté-Agel, Fernando
2013-04-01
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.
Rapid Plateau border size variations expected in three simple experiments on 2D liquid foams.
Gay, C; Rognon, P; Reinelt, D; Molino, F
2011-01-01
Up to a global scaling, the geometry of foams squeezed between two solid plates (2D GG foams) essentially depends on two independent parameters: the liquid volume fraction and the degree of squeezing (bubble thickness to diameter ratio). We describe it in two main asymptotic regimes: fully dry floor tiles, where the Plateau border radius is smaller than the distance between the solid plates, and dry pancakes, where it is larger. We predict a rapid variation of the Plateau border radius in one part of the pancake regime, namely when the Plateau border radius is larger than the inter-plate distance but smaller than the geometric mean of that distance and the bubble perimeter. This rapid variation is not related to any topological change in the foam: in all the regimes we consider, the bubbles remain in mutual lateral contact through films located at mid-height between both plates. We provide asymptotic predictions in different types of experiments on such 2D GG foams: when foam is being progressively dried or wetted, when it is being squeezed further or stretched, when it coarsens through film breakage or through inter-bubble gas diffusion. Our analysis is restricted to configurations close to equilibrium, as we do not include stresses resulting from bulk viscous flow or from non-homogeneous surfactant concentrations. We also assume that the inter-plate distance is sufficiently small for gravity to be negligible. The present work does not provide a method for measuring small Plateau border radii experimentally, but it indicates that large (and easily observable) Plateau borders should appear or disappear rather suddenly in some types of experiments with small inter-plate gaps. It also gives expected orders of magnitude that should be helpful for designing experiments on 2D GG foams. PMID:21253804
550 P.2d 1001 Page 1 17 Cal.3d 129, 550 P.2d 1001, 130 Cal.Rptr. 465
Kammen, Daniel M.
550 P.2d 1001 Page 1 17 Cal.3d 129, 550 P.2d 1001, 130 Cal.Rptr. 465 (Cite as: 17 Cal.3d 129, 550 P.2d 1001) BOALT STUDENTS PLEASE READ PAGES 7-9 (*140-*142 STARTING WITH: City's Power to Provide. Works. #12;550 P.2d 1001 Page 2 17 Cal.3d 129, 550 P.2d 1001, 130 Cal.Rptr. 465 (Cite as: 17 Cal.3d 129
Adaptive stereoscopic image conversion of 2D image
NASA Astrophysics Data System (ADS)
Lee, Jong-Ho; Kim, Jung-Jin; Kim, Eun-Soo
2001-11-01
In recent years, there have been many researches being done throughout the world on the 3D image conversion of 2D image. However, 3D image conversion of 2D image has many problems on obtaining the optimal stereopsis. Stereopsis is dominated to relative position of several objects and depth information within image. Accordingly, in this paper, as a new adaptive scheme for stereoscopic image conversion of 2D image is suggested. Two input images acquired by Stereo Camera have different disparity information to each other. Disparity map, based on disparity information, presents mutually different occulusion region in the left/right image. These depend on the left view & right view and front & rear view of the virtual image plane. If arbitrary threshold values are applied to disparity map, we can get segmented objects from the input image. Using the principle of horizontal parallax, segmented objects are shifted with optimal screen disparity. In this case, we can improve stereopsis by differential shifting.
Extension of Gkeyll Discontinuous Galerkin Kinetic Code to 2D
NASA Astrophysics Data System (ADS)
Shi, E. L.; Hakim, A.; Hammett, G. W.
2014-10-01
Gkeyll is a discontinuous Galerkin (DG) code under development for modeling the edge plasma in fusion devices and basic plasma experiments. High-order accurate, energy-conserving numerical algorithms for general Hamiltonian systems are implemented in Gkeyll. Details of the recent extension of the code dimensionality to 2D2V will be presented. Since DG schemes allow for flexibility in the choice of basis functions, we will discuss how various types of basis functions affect code accuracy and efficiency. Test problems in 2D, such as toroidal ITG instabilities and turbulence in a local limit, will be presented. We will also show initial results from 2D kinetic simulations of transport in a scrape-off layer plasma, using a specified diffusion coefficient to model radial transport. This research was supported by U.S. DOE Contract DE-AC02-09CH11466 and is part of the Max-Planck/Princeton Center for Plasma Physics.
On the Nonrelativistic 2D Purely Magnetic Supersymmetric Pauli Operator
P. Grinevich; A. Mironov; S. Novikov
2015-01-18
The Complete Manifold of Ground State Eigenfunctions for the Purely Magnetic 2D Pauli Operator is considered as a by-product of the new reduction found by the present authors few years ago for the Algebrogeometric Inverse Spectral Data (i.e. Riemann Surfaces and Divisors). This reduction is associated with the (2+1) Soliton Hierarhy containing a 2D analog of the famous "Burgers System". This article contains also exposition of the previous works made since 1980 including the first topological ideas in the space of quasimomenta. We present here also new results dedicated to the self-adjoint boundary problems for Pauli Operator. The 2D zero level "nonspectral" Bloch-Floquet functions give discrete points of additional spectrum similar to the "boundary states" of finite-gap 1D potentials in the gaps.
Computation of neutron fluxes in clusters of fuel pins arranged in hexagonal assemblies (2D and 3D)
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
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)
NASA Astrophysics Data System (ADS)
Chen, Shang-Shang; Li, Ben-Wen
2014-12-01
A collocation spectral domain decomposition method (CSDDM) based on the influence matrix technique is developed to solve radiative transfer problems within a participating medium of 2D partitioned domains. In this numerical approach, the spatial domains of interest are decomposed into rectangular sub-domains. The radiative transfer equation (RTE) in each sub-domain is angularly discretized by the discrete ordinates method (DOM) with the SRAPN quadrature scheme and then is solved by the CSDDM directly. Three test geometries that include square enclosure and two enclosures with one baffle and one centered obstruction are used to validate the accuracy of the developed method and their numerical results are compared to the data obtained by other researchers. These comparisons indicate that the CSDDM has a good accuracy for all solutions. Therefore this method can be considered as a useful approach for the solution of radiative heat transfer problems in 2D partitioned domains.
CYP2D44 polymorphisms in cynomolgus and rhesus macaques.
Uno, Yasuhiro; Uehara, Shotaro; Kohara, Sakae; Osada, Naoki; Murayama, Norie; Yamazaki, Hiroshi
2015-07-01
Macaques, including cynomolgus and rhesus macaques, are important animal species used in drug metabolism studies. CYP2D44 is expressed in cynomolgus macaque liver and encodes a functional drug metabolizing enzyme, metabolizing typical human CYP2D substrates such as bufuralol and dextromethorphan. CYP2D44 is highly homologous to human CYP2D6 that is known to be polymorphic with a large inter-individual variation in metabolic activities, however, genetic polymorphisms have not been investigated in macaque CYP2D44. In the present study, screening of 78 cynomolgus and 40 rhesus macaques found a total of 67 variants, including 64 non-synonymous variants, 1 nonsense mutation, and 2 frameshift mutations, and 1 gene conversion, of which 14, 19, and 15 variants were unique to Indochinese cynomolgus macaques, Indonesian cynomolgus macaques, and Chinese rhesus macaques, respectively. Eleven of the 64 non-synonymous variants were located in substrate recognition sites, the regions important for protein function. By site-directed mutagenesis and metabolic assays, S175N, V185L, A235G, R242G, R245K, and N337D showed substantially decreased activity in bufuralol 1'-hydroxylation as compared with wild-type proteins. Moreover, two null alleles (c.128T>del and c.664G>T) were found in Indonesian cynomolgus macaques, but not in Indochinese cynomolgus macaques or Chinese rhesus macaques. These results suggest that genetic polymorphisms might account for the variability of CYP2D44-dependent metabolism in macaques. PMID:25682269
Quantum quenches in 2D via arrays of coupled chains
NASA Astrophysics Data System (ADS)
James, Andrew; Konik, Robert
2015-03-01
Matrix product state (MPS) methods are extremely powerful when applied to strongly correlated systems in 1D. However they are less efficacious in 2D due to the `area law' growth of entanglement, limiting the system sizes that can be studied. We combine MPS methods with analytical results for integrable chains to build an algorithm that can study large (anisotropic) 2D many body quantum systems, because it reduces the need for a large `area'. As an example we describe the application of our method to quantum quenches of the 2 + 1 dimensional quantum Ising model.
Heterogeneous and anisotropic dynamics of a 2D gel
D. Orsi; L. Cristofolini; G. Baldi; A. Madsen
2012-02-03
We report X-ray Photon Correlation Spectroscopy (XPCS) results on a bidimensional (2D) gel formed by a Langmuir monolayer of gold nanoparticles. The system allows an experimental determination of the fourth order time correlation function which is compared to the usual second order correlation functions and to the mechanical response measured on macroscopic scale. The observed dynamics is anisotropic, heterogeneous and super-diffusive on the nanoscale. Different time scales, associated with fast heterogeneous dynamics inside 2D cages and slower motion of larger parts of the film, can be identified from the correlation functions.
Scaling Theory of Electrically Doped 2D Transistors
NASA Astrophysics Data System (ADS)
Ilatikhameneh, Hesameddin; Klimeck, Gerhard; Appenzeller, Joerg; Rahman, Rajib
2015-07-01
In this letter, it is shown that the existing scaling theories for chemically doped transistors cannot be applied to the novel class of electrically doped 2D transistors and the concept of equivalent oxide thickness (EOT) is not applicable anymore. Hence, a novel scaling theory is developed based on analytic solutions of the 2D Poisson equation. Full band atomistic quantum transport simulations verify the theory and show that the critical design parameters are the physical oxide thickness and distance between the gates. Accordingly, the most optimized electrically doped devices are those with the smallest spacing between the gates and the thinnest oxide, and not the smallest EOT.
2dF grows up: Echidna for the AAT
NASA Astrophysics Data System (ADS)
McGrath, Andrew; Barden, Sam; Miziarski, Stan; Rambold, William; Smith, Greg
2008-07-01
We present the concept design of a new fibre positioner and spectrograph system for the Anglo-Australian Telescope, as a proposed enhancement to the Anglo-Australian Observatory's well-known 2dF facility. A four-fold multiplex enhancement is accomplished by replacing the 400-fibre 2dF fibre positioning robot with a 1600-fibre Echidna unit, feeding three clones of the AAOmega optical spectrograph. Such a facility has the capability of a redshift 1 survey of a large fraction of the southern sky, collecting five to ten thousand spectra per night for a million-galaxy survey.
Radiative heat transfer in 2D Dirac materials
Pablo Rodriguez-Lopez; Wang-Kong Tse; Diego A. R. Dalvit
2015-02-02
We compute the radiative heat transfer between two sheets of 2D Dirac materials, including topological Chern insulators and graphene, within the framework of the local approximation for the optical response of these materials. In this approximation, which neglects spatial dispersion, we derive both numerically and analytically the short-distance asymptotic of the near-field heat transfer in these systems, and show that it scales as the inverse of the distance between the two sheets. Finally, we discuss the limitations to the validity of this scaling law imposed by spatial dispersion in 2D Dirac materials.
Noninvasive deep Raman detection with 2D correlation analysis
NASA Astrophysics Data System (ADS)
Kim, Hyung Min; Park, Hyo Sun; Cho, Youngho; Jin, Seung Min; Lee, Kang Taek; Jung, Young Mee; Suh, Yung Doug
2014-07-01
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.
Design of the LRP airfoil series using 2D CFD
NASA Astrophysics Data System (ADS)
Zahle, Frederik; Bak, Christian; Sřrensen, Niels N.; Vronsky, Tomas; Gaudern, Nicholas
2014-06-01
This paper describes the design and wind tunnel testing of a high-Reynolds number, high lift airfoil series designed for wind turbines. The airfoils were designed using direct gradient- based numerical multi-point optimization based on a Bezier parameterization of the shape, coupled to the 2D Navier-Stokes flow solver EllipSys2D. The resulting airfoils, the LRP2-30 and LRP2-36, achieve both higher operational lift coefficients and higher lift to drag ratios compared to the equivalent FFA-W3 airfoils.
Radiative heat transfer in 2D Dirac materials
NASA Astrophysics Data System (ADS)
Rodriguez-López, Pablo; Tse, Wang-Kong; Dalvit, Diego A. R.
2015-06-01
We compute the radiative heat transfer between two sheets of 2D Dirac materials, including topological Chern insulators and graphene, within the framework of the local approximation for the optical response of these materials. In this approximation, which neglects spatial dispersion, we derive both numerically and analytically the short-distance asymptotic of the near-field heat transfer in these systems, and show that it scales as the inverse of the distance between the two sheets. Finally, we discuss the limitations to the validity of this scaling law imposed by spatial dispersion in 2D Dirac materials.
Assessment of 2D resistivity structures using 1D inversions
Beard, Les Paul
1987-01-01
ASSESSMENT OF 2D RESISTIVITY STRUCTURES USING ID INVERSIONS A Thesis by LES PAUL BEARD Submitted to the Graduate College of Texas A kM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE May 198i Major... Subject: Geophysics ASSESSMENT OF 2D RESISTIVITY STRUCTURES USING 1D INVERSION A Thesis by LES PAUL BEARD Approved as to style and content by: F. D. Morgan (Chairman of Committee) A. F. Gangi (Member) R. . Pande (Member) E. R. Hoskins (Member...
Conservation Laws and 2D Black Holes in Dilaton Gravity
R. B. Mann
1992-06-10
A very general class of Lagrangians which couple scalar fields to gravitation and matter in two spacetime dimensions is investigated. It is shown that a vector field exists along whose flow lines the stress-energy tensor is conserved, regardless of whether or not the equations of motion are satisfied or if any Killing vectors exist. Conditions necessary for the existence of Killing vectors are derived. A new set of 2D black hole solutions is obtained for one particular member within this class of Lagrangians. One such solution bears an interesting resemblance to the 2D string-theoretic black hole, yet contains markedly different thermodynamic properties.
Radiative heat transfer in 2D Dirac materials.
Rodriguez-López, Pablo; Tse, Wang-Kong; Dalvit, Diego A R
2015-06-01
We compute the radiative heat transfer between two sheets of 2D Dirac materials, including topological Chern insulators and graphene, within the framework of the local approximation for the optical response of these materials. In this approximation, which neglects spatial dispersion, we derive both numerically and analytically the short-distance asymptotic of the near-field heat transfer in these systems, and show that it scales as the inverse of the distance between the two sheets. Finally, we discuss the limitations to the validity of this scaling law imposed by spatial dispersion in 2D Dirac materials. PMID:25965703
Quantum process tomography by 2D fluorescence spectroscopy
NASA Astrophysics Data System (ADS)
Pachón, Leonardo A.; Marcus, Andrew H.; Aspuru-Guzik, Alán
2015-06-01
Reconstruction of the dynamics (quantum process tomography) of the single-exciton manifold in energy transfer systems is proposed here on the basis of two-dimensional fluorescence spectroscopy (2D-FS) with phase-modulation. The quantum-process-tomography protocol introduced here benefits from, e.g., the sensitivity enhancement ascribed to 2D-FS. Although the isotropically averaged spectroscopic signals depend on the quantum yield parameter ? of the doubly excited-exciton manifold, it is shown that the reconstruction of the dynamics is insensitive to this parameter. Applications to foundational and applied problems, as well as further extensions, are discussed.
The Anglo-Australian Observatory's 2dF Facility
I. J. Lewis; R. D. Cannon; K. Taylor; K. Glazebrook; J. A. Bailey; I. K. Baldry; J. R. Barton; T. J. Bridges; G. B. Dalton; T. J. Farrell; P. M. Gray; A. Lankshear; C. McCowage; I. R. Parry; R. M. Sharples; K. Shortridge; G. A. Smith; J. Stevenson; J. O. Straede; L. G. Waller; J. D. Whittard; J. K. Wilcox; K. C. Willis
2002-01-01
The 2dF (Two-degree Field) facility at the prime focus of the\\u000aAnglo-Australian Telescope provides multiple object spectroscopy over a 2\\u000adegree field of view. Up to 400 target fibres can be independently positioned\\u000aby a complex robot. Two spectrographs provide spectra with resolutions of\\u000abetween 500 and 2000, over wavelength ranges of 440nm and 110nm respectively.\\u000aThe 2dF facility began
Nomenclature for human CYP2D6 alleles.
Daly, A K; Brockmöller, J; Broly, F; Eichelbaum, M; Evans, W E; Gonzalez, F J; Huang, J D; Idle, J R; Ingelman-Sundberg, M; Ishizaki, T; Jacqz-Aigrain, E; Meyer, U A; Nebert, D W; Steen, V M; Wolf, C R; Zanger, U M
1996-06-01
To standardize CYP2D6 allele nomenclature, and to conform with international human gene nomenclature guidelines, an alternative to the current arbitrary system is described. Based on recommendations for human genome nomenclature, we propose that alleles be designated by CYP2D6 followed by an asterisk and a combination of roman letters and arabic numerals distinct for each allele with the number specifying the key mutation and, where appropriate, a letter specifying additional mutations. Criteria for classification as a separate allele and protein nomenclature are also presented. PMID:8807658
Quantum process tomography by 2D fluorescence spectroscopy.
Pachón, Leonardo A; Marcus, Andrew H; Aspuru-Guzik, Alán
2015-06-01
Reconstruction of the dynamics (quantum process tomography) of the single-exciton manifold in energy transfer systems is proposed here on the basis of two-dimensional fluorescence spectroscopy (2D-FS) with phase-modulation. The quantum-process-tomography protocol introduced here benefits from, e.g., the sensitivity enhancement ascribed to 2D-FS. Although the isotropically averaged spectroscopic signals depend on the quantum yield parameter ? of the doubly excited-exciton manifold, it is shown that the reconstruction of the dynamics is insensitive to this parameter. Applications to foundational and applied problems, as well as further extensions, are discussed. PMID:26049462
T. Filik; T. E. Tuncer
2009-01-01
A new approach is proposed for two-dimensional (2-D) direction-of-arrival (DOA) estimation with arbitrary array geometries, which is based on array interpolation. The method provides automatically paired source azimuth and elevation angle estimates. Furthermore it is possible to estimate D sources with D+1 sensor. 2-D array interpolation errors are minimized by using Wiener formulation. Proposed method is applied to the two
Proof in Transformation Geometry
ERIC Educational Resources Information Center
Bell, A. W.
1971-01-01
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)
ERIC Educational Resources Information Center
Emenaker, Charles E.
1999-01-01
Describes a sixth-grade interdisciplinary geometry unit based on Charles Dickens's "A Christmas Carol". Focuses on finding area, volume, and perimeter, and working with estimation, decimals, and fractions in the context of making gingerbread houses. (ASK)
Flyby Geometry Optimization Tool
NASA Technical Reports Server (NTRS)
Karlgaard, Christopher D.
2007-01-01
The Flyby Geometry Optimization Tool is a computer program for computing trajectories and trajectory-altering impulsive maneuvers for spacecraft used in radio relay of scientific data to Earth from an exploratory airplane flying in the atmosphere of Mars.
NSDL National Science Digital Library
Brown, Kevin
"Informal notes" by Kevin Brown on geometry: constructing the heptadecagon, what mirrors do, the golden pentagon, the grazing goat and the lune, Napoleon's theorem, chess boards, Diophantine geodesic boxes, Zeno's mice and the logarithmic spiral, and many more.
ERIC Educational Resources Information Center
Potter, Gretchen
1976-01-01
After a unit on Euclidean geometry which stresses both the development of intuition and the use of deductive methods, non-Euclidean concepts are introduced by having students read and consider science fiction stories. (SD)
Manuel Hohmann
2014-09-11
From general relativity we have learned the principles of general covariance and local Lorentz invariance, which follow from the fact that we consider observables as tensors on a spacetime manifold whose geometry is modeled by a Lorentzian metric. Approaches to quantum gravity, however, hint towards a breaking of these symmetries and the possible existence of more general, non-tensorial geometric structures. Possible implications of these approaches are non-tensorial transformation laws between different observers and an observer-dependent notion of geometry. In this work we review two different frameworks for observer dependent geometries, which may provide hints towards a quantization of gravity and possible explanations for so far unexplained phenomena: Finsler spacetimes and Cartan geometry on observer space. We discuss their definitions, properties and applications to observers, field theories and gravity.
José Natário
\\u000a In this chapter we discuss the non-Euclidean geometry of curved surfaces, using the sphere as our primary example. We find\\u000a that all the information about the geometry of the surface is contained in the expression for the distance between two nearby\\u000a points in some coordinate system, called the metric. For example, the distance between two distant points can be found
NSDL National Science Digital Library
2007-12-12
Science UTM offers online articles and activities for people who like science. Science U and the web-design and development company that owns and operates the website, Geometry Technologies, were formed as a result of the closure of The Geometry Center at the University of Minnesota. One of the conditions of that grant, which funded The Geometry Center and ended in 1998, was that the Center would find a way to keep their materials available to the public. In anticipation of the day when the Geometry Center goes offline, they are slowly migrating materials to this website. The Geometry Center section at Science U offers lessons on solids using interactive models, geometry tiling activities, an interactive fractal generator, and many other puzzles, articles and activities. Visitors can search their resources using an online query form or by browsing the topic index, subject listing or content listing. The content listing gives you an idea of the different types of resources available, such as articles, facts and figures, classroom materials, online simulations, hands-on-projects, or software. The Science U also offers other sections on astronomy, graphic arts, and a library with various online and print resources on science.
Radioligand receptor assay for 25-hydroxyvitamin D2/D3 and 1 alpha, 25-dihydroxyvitamin D2/D3.
Hughes, M R; Baylink, D J; Jones, P G; Haussler, M R
1976-07-01
A competitive protein binding assay for measurement of the plasma concentration of 1 alpha, 25-dihydroxyvitamin D3 [1alpha, 25-(OH)2D3] has been extended to include the immediate precursor of this hormone, 25-hydroxyvitamin D3 (25-OHD3). In addition, the assay system is capable of measuring the two metabolic products of ergocalciferol, namely. 25-hydroxyvitamin D2 (25-OHD2) and 1alpha, 25-dihydroxyvitamin D2 [1alpha, 25-(OH)2D2]. The target tissue assay system consists of a high affinity cytosol receptor protein that binds the vitamin D metabolites and a limited number of acceptor sites on the nuclear chromatin. By utilizing a series of chromatographic purification steps, a single plasma sample can be assayed for any of the four vitamin D metabolites either individually or combined. Therefore, the assay procedure allows for both the quantitative and qualitative assessment of the total active vitamin D level in a given plasma sample. To show that the binding assay was capable of measuring 1alpha, 25-(OH)2D2 as well as 1alpha, 25 (OH)2D3, two groups of rats were raised. One group, supplemented with vitamin D3, produced assayable material that represented 1alpha, 25-(OH)2D3. The other group, fed only vitamin D2 in the diet, yielded plasma containing only 1alpha, 25-(OH)2D2 as the hormonal form of the vitamin. The circulating concentrations of the two active sterols were nearly identical (15 ng/100 ml) in both groups, indicating that the competitive binding assay can be used to measure both hormonal forms in plasma. In a separate experiment, 1alpha, 25-(OH)2D2 was generated in an in vitro kidney homogenate system using 25-OHD2 as substrate. Comparison of this sterol with 1alpha, 25-(OH)2D3 in the assay system showed very similar binding curves; the D2 form was slightly less efficient (77%). Comparison of the respective 25-hydroxy forms (25-OHD2 vs. 25-OHD3) at concentrations 500-fold that of 1alpha, 25-(OH)2D3, again suggested that the binding of the D2 metabolite was slightly less efficient (71%). Finally, the assay was employed to measure the total active vitamin D metabolite pools in the plasma of normal subjects and patients with varying degrees of hypervitaminosis D. The normal plasma levels of 25-OHD and 1alpha, 25-(OH)2D measured in Tucson adults were 25-40 ng/ml and 2.1-4.5 ng/100 ml, respectively. Both sterols were predominately (greater than 90%) in the form of vitamin D3 metabolites in this environment. Typical cases of hypervitaminosis D exhibited approximately a 15-fold increase in the plasma 25-OHD concentration, and a dramatic changeover to virtually all metabolites existing in the form of D2 vitamins. In contrast, the circulating concentration of 1alpha, 25-(OH)2D was not substantially enhanced in vitamin D-intoxicated patients. We therefore conclude that hypervitaminosis D is not a result of abnormal plasma levels of 1alpha, 25-(OH)2D but may be cuased by an excessive circulating concentration of 25-OHD. PMID:1084355
Magnetoencephalography in ellipsoidal geometry
George Dassios; Fotini Kariotou
2003-01-01
An exact analytic solution for the forward problem in the theory of biomagnetics of the human brain is known only for the (1D) case of a sphere and the (2D) case of a spheroid, where the excitation field is due to an electric dipole within the corresponding homogeneous conductor. In the present work the corresponding problem for the more realistic
Flow-induced protein crystallization: Macroscopic effects on 2D crystals
NASA Astrophysics Data System (ADS)
Young, James; Posada, David; Hirsa, Amir; Lopez, Juan
2012-11-01
Proteins must first be crystallized before their molecular structure can be studied in detail. However, crystallizing protein is a challenging task which is often met with limited success. Although 2-D protein crystals at the air/water interface are usually obtained under quiescent conditions, it was recently shown that crystallization can be enhanced by a shearing flow. Here we examine the relationship between Reynolds number and the crystal growth process using the deep-channel surface viscometer geometry. It consists of an annular region bounded by stationary inner and outer cylinders and driven by a constant rotation of the floor. The interfacial velocity measurements are compared to Navier-Stokes computations with the Boussinesq-Scriven surface model. The interfacial film is lifted onto a solid substrate, and the protein crystals are observed via optical and atomic force microscopy. For a particular protein surface concentration, a Reynolds number threshold has been identified for flow-induced crystallization. This flow geometry also allows for the determination of the surface shear viscosity, which provides a quantitative measure of the mesoscale interactions associated with protein crystallization.
Study of the mechanical behavior of a 2-D carbon-carbon composite
Avery, W.B.; Herakovich, C.T.
1987-08-01
The objective of this study was to observe and characterize the out-of-plane fracture of a 2-D carbon-carbon composite and to gain an understanding of the factors influencing the stress distribution in such a laminate. Finite element analysis of a two-ply carbon-carbon composite under in-plane, out-of-plane, and thermal loading were performed. The results indicated that under out-of-plane loading sigma sub x and tau sub xz were strongly dependent on stacking sequence, undulation aspect ratio, and undulation offset ratio, but sigma sub z and sigma sub y were relatively independent of geometry. 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 from those predicted assuming the fiber to be transversely isotropic.
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
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.
[Denoising worm artifacts of elastogram using 2-D wavelet shrinkage].
Cui, Shaoguo; Liu, Dongquan
2011-06-01
This paper proposes a technique to denoise the worm artifacts of elastogram using 2-D wavelet shrinkage denoising method. Firstly, strain estimate matrix including worm artifacts was decomposed to 3 levels by 2-D discrete wavelet transform with Sym8 wavelet function, and the thresholds were obtained using Birg6-Massart algorithm. Secondly, all the high frequency coefficients on different levels were quantized by using hard threshold and soft threshold function. Finally, the strain estimate matrix was reconstructed by using the 3rd layer low frequency coefficients and other layer quantized high frequency coefficients. The simulation results illustrated that the present technique could efficiently denoise the worm artifacts, enhance the elastogram performance indices, such as elastographic signal-to-noise ratio (SNRe) and elastographic contrast-to-noise ratio (CNRe), and could increase the correlation coefficient between the denoised elastogram and the ideal elastogram. In comparison with 2-D low-pass filtering, it could also obtain the higher elastographic SNRe and CNRe, and have clearer hard lesion edge. In addition, the results demonstrated that the proposed technique could suppress worm artifacts of elastograms for various applied strains. This work showed that the 2-D wavelet shrinkage denoising could efficiently denoise the worm artifacts of elastogram and enhance the performance of elastogram. PMID:21774202
A 2D semiconductor-self-assembled monolayer photoswitchable diode.
Margapoti, Emanuela; Li, Juan; Ceylan, Özlem; Seifert, Max; Nisic, Filippo; Anh, Tuan Le; Meggendorfer, Felix; Dragonetti, Claudia; Palma, Carlos-Andres; Barth, Johannes V; Finley, Jonathan J
2015-02-25
A switchable diode in a 2D semiconductor-molecular junction heterostructure is reported. MoS2 is exfoliated on top of a monolayer of azobenzene-substituted thiols on gold. Photoisomerization of the azobenzenes results in switching between a rectifier with rectifying ratios of 10(4) and a conductive state, as revealed by conducting atomic force microscopy. PMID:25641369
Face Recognition Using 2D and 3D Facial Data
Kyong I. Chang; Kevin W. Bowyer; Patrick J. Flynn
2003-01-01
Results are presented for the largest experimental study to date that investigates the comparison and combination of 2D and 3D face recognition. To our knowledge, this is also the only such study to incorporate signicant time lapse be- tween gallery and probe image acquisition, and to look at the effect of depth resolution. Recognition results are ob- tained in (1)
Maximally Fully Adaptive Routing in 2D Meshes
Christopher J. Glass; Lionel M. Ni
1992-01-01
Previous authors have proposed that wormhole routing in 2D meshes be made fullyadaptive by doubling the number of channels in one of the two dimensions. We examinethis proposition both using a new model for designing adaptive routing algorithmsand using simulations. The model involves analyzing the directions in which packetscan turn in a network and the cycles that the turns can
2D Jet Simulation Testing SUNY Stony Brook
McDonald, Kirk
2D Jet Simulation Testing Yan Zhan SUNY Stony Brook Feb 3rd 2014 1 #12;Mesh & Boundary Conditions Inlet Boundary Condition 13 H. Liu, J. Wang, R.J. Brown and N. Kelson, Computational Fluid Dynamic (CFD) Simulation of Ultrahigh Velocity Abrasive Water jet, Key Engineering Materials, Vols. 233236 (2003), 477482
Hierarchical mesh adaptation of 2D quadrilateral elements
E. T. Moyer
1995-01-01
In this paper, we present some examples which illustrate the use of adaptive finite element analysis using a new hierarchical refinement algorithm for 2D quadrilateral elements. Projection type a posteriori error estimators based on a global stress smoothing and a simple stress averaging scheme have been used. The algorithm produces well refined meshes for some simple examples which contain stress
The 2D lid-driven cavity problem revisited
Charles-Henri Bruneau; Mazen Saad
2006-01-01
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.
2D Shape Classification Using Multifractional Brownian Motion
Bicego, Manuele
2D Shape Classification Using Multifractional Brownian Motion Manuele Bicego and Alessandro Trudda is to characterize the contour of an object using the multifractional Brownian motion (mBm), a mathe- matical method is to characterize the contour of each object using the multifractional Brownian motion (mBm) [4,5,6], a mathematical
Discrepant Results in a 2-D Marble Collision
ERIC Educational Resources Information Center
Kalajian, Peter
2013-01-01
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…
Protein Folding in 3-d and 2-d
NSDL National Science Digital Library
Brian White (University of Massachusetts; )
2006-06-18
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.
SAR imaging via modern 2-D spectral estimation methods
Stuart R. Degraaf
1998-01-01
Discusses the use of modern 2D spectral estimation algorithms for synthetic aperture radar (SAR) imaging. The motivation for applying power spectrum estimation methods to SAR imaging is to improve resolution, remove sidelobe artifacts, and reduce speckle compared to what is possible with conventional Fourier transform SAR imaging techniques. This paper makes two principal contributions to the field of adaptive SAR
2-D airfoil tests including side wall boundary layer measurements
W. Bartelheimer; K. H. Horstmann; W. Puffert-Meissner
1994-01-01
The data presented in this contribution were obtained in the DLR Transonic Wind Tunnel Braunschweig. The intent of the experiment was to provide data giving information on the development of the TWB-side wall boundary layer in the presence of a typical transonic airfoil model for further investigation of the influence of the side wall boundary layer on 2-D airfoil measurements.
RICE UNIVERSITY Millimeter Wave Transmission Spectroscopy of 2D
Natelson, Douglas
RICE UNIVERSITY Millimeter Wave Transmission Spectroscopy of 2D Electron and Hole Systems was accepted to Rice's Physics and Astronomy Department two weeks before classes started and arrived one week myself at Rice University with friends and mentors who have been invaluable resources. They have made
Hopkinson bar simulation using DYNA2D. Revision 1
Smith, J.A.; Glover, T.A.
1985-05-01
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.
Numerical reconstruction of 2D potential fields from discrete measurements
J. Irša; A. N. Galybin
2011-01-01
Purpose – The purpose of this paper is to consider reconstructions of potential 2D fields from discrete measurements. Two potential processes are addressed, steady flow and heat conduction. In the first case, the flow speed and streamlines are determined from the discrete data on flow directions, in the second case, the temperature and flux are recovered from temperature measurements at
Computational Predictions of Stable 2D Arrays of Bidisperse Particles
() of 0.375. We found that interparticle forces were essential to stabilize the LS (the two-dimensional NaCl-stabilized gold particles with distinct bimodal size distributions spontaneously order into twoComputational Predictions of Stable 2D Arrays of Bidisperse Particles Brooks D. Rabideau and Roger
Reconstructing 3D Human Pose from 2D Image Landmarks
Sheikh, Yaser Ajmal
the configurations spanned in the corpus, ensuring anthropometric plausibility while discouraging impossible that violate anthropometric con- straints such as limb proportions, yet yield a projection in 2D that is plausible. The goal is therefore to develop an activity-independent model while ensuring anthropometric
ADVANCES IN 2-D CORRELATION IN NIR SPECTROSCOPY
Technology Transfer Automated Retrieval System (TEKTRAN)
Two-dimensional (2-D) vibrational correlation spectroscopy has now advanced to the stage of realizing many of its touted advantages. Those advantages primarily are: elucidation of chemical interactions of functional groups, simplification of complex spectra, enhancement of spectral resolution by sp...
Particle trajectories in 2D granular avalanches with imposed vibrations
Nora Swisher; Brian Utter
2011-01-01
We study particle trajectories of photoelastic grains in a 2D circular rotating drum subjected to imposed vertical vibrations in order to characterize the jamming behavior of granular materials. Jamming appears in many systems (grain silos & chutes, landslides, mixing industrial materials, etc.) and vibration (granular temperature) is a primary factor in the jamming\\/unjamming transition. Images are taken and each particle's
VLSI architecture for fast 2D discrete orthonormal wavelet transform
Henry Y. H. Chuang; Ling Chen
1995-01-01
The discrete wavelet transform (DWT) provides a new method for signal\\/image analysis where high frequency components are studied with finer time resolution and low frequency components with coarser time resolution. It decomposes a signal or an image into localized contributions for multiscale analysis. In this paper, we present a parallel pipelined VLSI array architecture for 2D dyadic separable DWT. The
"Stem Cell Migration on 2D Biomaterials Platforms" Tyler Vlass
Mountziaris, T. J.
"Stem Cell Migration on 2D Biomaterials Platforms" Tyler Vlass Faculty Mentor: Dr. Shelly Peyton, Chemical Engineering The research project I will be working on this summer deals with stem cell motility. I will be building off of research done by the Peyton Lab. When testing stem cell movement on 3D scaffolds
Yield analysis of 2D hexagonal VLSI\\/WSI arrays
Afzel Noore; S. Cambam
1991-01-01
This paper proposes techniques for determining the yield of redundant 2D hexagonal VLSI and WSI arrays. Such arrays are very useful in parallel processing, distributed processing and systolic array applications. Redundancy is implemented at the interstitial spaces of the array structure and reconfiguration is performed locally in order to keep the interconnections short and simple. The first reconfiguration strategy models
2D Resistivity in Discontinuous Permafrost, Fort Wainwright, Alaska
B. N. Astley; C. F. Snyder; K. Sturtevant
2004-01-01
2D resistivity profiles were collected in an area containing discontinuous permafrost, fractured bedrock, and groundwater contamination on Fort Wainwright, Alaska in June 2004. The stratigraphy consists of the Chena Alluvium over weathered and fractured Birch Hill Schist. Contaminant migration pathways are complex due to numerous fractures and frozen zones. Our purpose was to supplement existing permafrost data and to identify
2D superconductivity: Classification of universality classes by infinite symmetry
NASA Astrophysics Data System (ADS)
Trugenberger, Carlo A.
2005-06-01
I consider superconducting condensates which become incompressible in the infinite gap limit. Classical 2D incompressible fluids possess the dynamical symmetry of area-preserving diffeomorphisms. I show that the corresponding infinite dynamical symmetry of 2D superconducting fluids is the coset {W?W}/{U(1}, with W the chiral algebra of quantum area-preserving diffeomorphisms and I derive its minimal models. These define a discrete set of 2D superconductivity universality classes which fall into two main categories: conventional superconductors with their vortex excitations and unconventional superconductors. These are characterized by a broken U(1?U(1 symmetry and are labeled by an integer level m. They possess neutral spinon excitations of fractional spin and statistics S=?/2?={m-12m, which carry also an SU(m) isospin quantum number; this hidden SU(m) symmetry implies that these anyon excitations are non-Abelian. The simplest unconventional superconductor is realized for m=2: in this case the spinon excitations are semions (half-fermions). My results show that spin-charge separation in 2D superconductivity is a universal consequence of the infinite symmetry of the ground state. This infinite symmetry and its superselection rules realize a quantum protectorate in which the neutral spinons can survive even as soft modes on a rigid, spinless charge condensate.
2D Transformation Optics using Anisotropic Transmission-Line Metamaterials
Eleftheriades, George V.
2D Transformation Optics using Anisotropic Transmission-Line Metamaterials Michael Zedler *, George-dimensional metamaterial unit cell which synthesizes equivalent material parameters needed for 'transformation optics', as introduced in [1]. The proposed metamaterial consists of a grid of reactively loaded transmission
Shed NKG2D ligand boosts NK cell immunity.
Narni-Mancinelli, Emilie; Vivier, Eric
2015-06-01
Ligands for natural killer (NK) cell activating receptors can be released from tumor cells and are believed to promote tumor growth by acting as decoys for effector lymphocytes. In a recent paper published in Science, Deng et al. report another scenario in which a shed form of the MULT1 mouse NKG2D ligand boosts NK cell functions. PMID:25849247
A potential based panel method for 2-D hydrofoils
Sakir Bal
1998-01-01
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
SAR Image Superresolution via 2-D Adaptive Extrapolation$
Fisher III, John
of a nonparametric two dimensional (2-D) procedure to extrapolate a signal, an extension of the Adaptive Weighted, synthetic aperture radar, extrapolation 1. Introduction There is an increasing interest in the use of superresolution methods to form Synthetic Aperture Radar (SAR) images [1], [2], [3], [4], [5], [6], [7], [8
FINITE CONNECTIONS FOR SUPERCRITICAL BERNOULLI BOND PERCOLATION IN 2D
FINITE CONNECTIONS FOR SUPERCRITICAL BERNOULLI BOND PERCOLATION IN 2D MASSIMO CAMPANINO, DMITRY for super-critical Bernoulli bond percolation on Z2 . These asymptotics are based on a detailed fluctuation analysis of long finite super-critical clusters or, more precisely, of dual open (sub-critical) loops which
On monochromatic arm exponents for 2D critical percolation
Paris-Sud XI, Université de
On monochromatic arm exponents for 2D critical percolation Vincent Beffara Pierre Nolin Abstract We investigate the so-called monochromatic arm exponents for critical percolation in two dimensions main result is that the monochromatic j-arm exponent is strictly between the polychromatic j-arm and (j
Modeling and application of 2D photonic band gap structures
Mizan Rahman; Maria A. Stuchly
2001-01-01
Photonic band gap (PBG) structures have originally been explored in electro-optics. During the last five years, 2D planar PBG circuits have also been used at microwave frequencies. PBG structures behave as high impedance surfaces and suppress surface waves in one or more frequency ranges. Until now, these circuits have only been reliably modeled by numerical methods. A new equivalent circuit
2D TwoPhase Jet Simulations SUNY Stony Brook
McDonald, Kirk
, Volume Fraction Of Water Snapshots 4 #12;Axial Velocity Contour (Mercury Air ) [click to watch the movie] VOF CLSVOF 5 #12;Volume Fraction Of Water (Mercury Air ) [click to watch the movie] VOF Of Water Snapshots · 2D WaterAir Jet Movies · Axial Velocity Contour, Volume Fraction Of Water
ENVIRONMENTAL EFFECTS OF DREDGING AND DISPOSAL (E2-D2)
US Army Corps of Engineers public web site for the "Environmental Effects of Dredging and Disposal" ("E2-D2") searchable database of published reports and studies about environmental impacts associated with dredging and disposal operations. Many of the reports and studies are ava...
2D and 3D Elasticity Imaging Using Freehand Ultrasound
Drummond, Tom
2D and 3D Elasticity Imaging Using Freehand Ultrasound Joel Edward Lindop Pembroke College March to mechanical properties (e.g., stiffness) to which conventional forms of ultrasound, X-ray and magnetic that occur between the acquisition of multiple ultrasound images. Likely applications include improved
The 2-D Leap-Frog: Integrability, Noise, and Digitization
Kozera, Ryszard
The 2-D Leap-Frog: Integrability, Noise, and Digitization Lyle Noakes a and Ryszard Kozera b and Software Engineering b , 35 Stirling Highway, Crawley WA 6009, Australia Summary. The 1-D Leap-Frog paper ? we adapt Leap- Frog to solve an optimization problem in computer vision. The vision problem
Skrynnikov, Nikolai
optimized spectroscopy, isotopic labeling, malate synthase G, high molecular weight proteins AbstractArticle Comparison of 13 CH3, 13 CH2D, and 13 CHD2 methyl labeling strategies in proteins Jason E A comparison of three labeling strategies for studies involving side chain methyl groups in high molecular
Realistic Picture of 2D Harmonic Oscillator Coherent States
Michel Gondran
2005-11-30
We show that a 2D harmonic oscillator coherent state is a soliton which has the same evolution as a spinning top: the center of mass follows a classical trajectory and the particle rotates around its center of mass in the same direction as its spin with the harmonic oscillator frequency.
Synthesis, Characterization, Properties, and Tribological Performance of 2D Nanomaterials
He, Xingliang
2014-04-25
. Using 2D nanoparticles provides fundamentally new solution to reduce friction-induced energy loss in liquid lubrication. New understandings on nano-fluidics and nano-rheology will be beneficial to a broad range of tribology-related applications, e.g...
Some problems connected with 2D modeling of geosynthetic tubes
Josef Malík
2009-01-01
Some problems connected with 2D modeling of geosynthetic tubes on rigid foundations are studied. Basic equations are derived and analyzed. The analysis of the equations is based on the implicit function theorem. Geosynthetic tubes are made of a special fabric and then filled with water or slurry. After being filled tubes take certain shapes and tensions are induced in the
Students Discovering Spherical Geometry Using Dynamic Geometry Software
ERIC Educational Resources Information Center
Guven, Bulent; Karatas, Ilhan
2009-01-01
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…
The Anglo-Australian Observatory's 2dF Facility
I. J. Lewis; R. D. Cannon; K. Taylor; K. Glazebrook; J. A. Bailey; I. K. Baldry; J. R. Barton; T. J. Bridges; G. B. Dalton; T. J. Farrell; P. M. Gray; A. Lankshear; C. McCowage; I. R. Parry; R. M. Sharples; K. Shortridge; G. A. Smith; J. Stevenson; J. O. Straede; L. G. Waller; J. D. Whittard; J. K. Wilcox; K. C. Willis
2002-02-08
The 2dF (Two-degree Field) facility at the prime focus of the Anglo-Australian Telescope provides multiple object spectroscopy over a 2 degree field of view. Up to 400 target fibres can be independently positioned by a complex robot. Two spectrographs provide spectra with resolutions of between 500 and 2000, over wavelength ranges of 440nm and 110nm respectively. The 2dF facility began routine observations in 1997. 2dF was designed primarily for galaxy redshift surveys and has a number of innovative features. The large corrector lens incorporates an atmospheric dispersion compensator, essential for wide wavelength coverage with small diameter fibres. The instrument has two full sets of fibres on separate field plates, so that re-configuring can be done in parallel with observing. The robot positioner places one fibre every 6 seconds, to a precision of 0.3 arcsec (20micron) over the full field. All components of 2dF, including the spectrographs, are mounted on a 5-m diameter telescope top-end ring for ease of handling and to keep the optical fibres short in order to maximise UV throughput . There is a pipeline data reduction system which allows each data set to be fully analysed while the next field is being observed. In this paper we provide the historical background to the 2dF facility, the design philosophy, a full technical description and a summary of the performance of the instrument. We also briefly review its scientific applications and possible future developments.
2D/3D Image Registration using Regression Learning
Chou, Chen-Rui; Frederick, Brandon; Mageras, Gig; Chang, Sha; Pizer, Stephen
2013-01-01
In computer vision and image analysis, image registration between 2D projections and a 3D image that achieves high accuracy and near real-time computation is challenging. In this paper, we propose a novel method that can rapidly detect an object’s 3D rigid motion or deformation from a 2D projection image or a small set thereof. The method is called CLARET (Correction via Limited-Angle Residues in External Beam Therapy) and consists of two stages: registration preceded by shape space and regression learning. In the registration stage, linear operators are used to iteratively estimate the motion/deformation parameters based on the current intensity residue between the target projec-tion(s) and the digitally reconstructed radiograph(s) (DRRs) of the estimated 3D image. The method determines the linear operators via a two-step learning process. First, it builds a low-order parametric model of the image region’s motion/deformation shape space from its prior 3D images. Second, using learning-time samples produced from the 3D images, it formulates the relationships between the model parameters and the co-varying 2D projection intensity residues by multi-scale linear regressions. The calculated multi-scale regression matrices yield the coarse-to-fine linear operators used in estimating the model parameters from the 2D projection intensity residues in the registration. The method’s application to Image-guided Radiation Therapy (IGRT) requires only a few seconds and yields good results in localizing a tumor under rigid motion in the head and neck and under respiratory deformation in the lung, using one treatment-time imaging 2D projection or a small set thereof. PMID:24058278
Direct comparison of 2D PIV and stereoscopic PIV measurements
NASA Astrophysics Data System (ADS)
Yoon, Jong-Hwan; Lee, Sang-Joon
2002-10-01
A stereoscopic particle image velocimetry (PIV) measurement system based on the translation configuration was developed and applied to the flow behind a forward-swept axial-fan with five blades in a water tank. The 3D calibration procedure was employed to compensate the distortion and refraction of particle images. The perspective error caused by the out-of-plane motion was estimated by direct comparison of the 2D PIV and stereoscopic PIV (SPIV) results. The SPIV and 2D PIV comparison was carried out for the particle images captured simultaneously. The difference of mean velocity data measured by 2D PIV and SPIV techniques is nearly proportional to the mean out-of-plane velocity component. The difference appears to be relatively large in the region near the fan blade having higher out-of-plane motion. The perspective error estimated from the calibration data and mean out-of-plane velocity data agrees with the mean velocity difference between the 2D PIV and SPIV results. The turbulence intensity measured by the 2D PIV method is overestimated in comparison to that of the SPIV method due to the projected velocity fluctuations of the out-of-plane velocity component. The turbulent fluctuations caused by the out-of-plane velocity component were estimated by multiplication of the incident angle obtained in the calibration procedure and out-of-plane velocity fluctuations. The estimated perspective fluctuation of the out-of-plane velocity component was compared with the difference measured by the two methods. In SPIV measurements of turbulent statistics, therefore, the ratio of out-of-plane to in-plane RMS error determined from the system set-up should be considered in order to obtain reliable results.
The physics of 2D microfluidic droplet ensembles
NASA Astrophysics Data System (ADS)
Beatus, Tsevi; Bar-Ziv, Roy H.; Tlusty, Tsvi
2012-07-01
We review non-equilibrium many-body phenomena in ensembles of 2D microfluidic droplets. The system comprises of continuous two-phase flow with disc-shaped droplets driven in a channel, at low Reynolds number of 10-4-10-3. The basic physics is that of an effective potential flow, governed by the 2D Laplace equation, with multiple, static and dynamic, boundaries of the droplets and the walls. The motion of the droplets induces dipolar flow fields, which mediate 1/r2 hydrodynamic interaction between the droplets. Summation of these long-range 2D forces over droplet ensembles converges, in contrast to the divergence of the hydrodynamic forces in 3D. In analogy to electrostatics, the strong effect of boundaries on the equations of motion is calculated by means of image dipoles. We first consider the dynamics of droplets flowing in a 1D crystal, which exhibits unique phonon-like excitations, and a variety of nonlinear instabilities-all stemming from the hydrodynamic interactions. Narrowing the channel results in hydrodynamic screening of the dipolar interactions, which changes salient features of the phonon spectra. Shifting from a 1D ordered crystal to 2D disordered ensemble, the hydrodynamic interactions induce collective density waves and shocks, which are superposed on single-droplet randomized motion and dynamic clustering. These collective modes originate from density-velocity coupling, whose outcome is a 1D Burgers equation. The rich observational phenomenology and the tractable theory render 2D droplet ensembles a suitable table-top system for studying non-equilibrium many-body physics with long-range interactions.
An Introduction to Projective Geometry
NSDL National Science Digital Library
Birchfield, Stan
The contents of this paper include: The Projective Plane; Projective Space; Projective Geometry Applied to Computer Vision; Demonstration of Cross Ratio in P^1; and a bibliography. (Euclidean geometry is a subset of projective geometry, and there are two geometries between them: similarity and affine.) Also at http://vision.stanford.edu/~birch/projective/.
Topics in Geometry Olga Kharlampovich
Kharlampovich, Olga
. Symmetry in the real world Â˛ Euclidean and non-Euclidean geometry 1. History 2. Plane Euclidean geometry, 3 mathematics, AMS, Mathematical world, Vol. 5, 1996 P.J. Ryan, Euclidean and non-Euclidean geometry. AÂ±ne transformations in the Euclidean plane, 4. Finite groups of isometries of E2 , 5. Geometry
TRACTOR CALCULI FOR PARABOLIC GEOMETRIES
ANDREAS CAP; A. ROD GOVER
1999-01-01
Parabolic geometries may be considered as curved analogues of the homogeneous spaces G=P where G is a semisimple Lie group and P G a parabolic subgroup. Conformal geometries and CR geometries are exam- ples of such structures. We present a uniform description of a calculus, called tractor calculus, based on natural bundles with canonical linear connections for all parabolic geometries.
REFINAMIENTO EN PARALELO DE MALLAS GEOMÉTRICAS EN 2D PARALLEL REFINEMENT OF GEOMETRICAL MESHES IN 2D
Mario E. Mellado; Pedro Rodríguez; Javier Camiruaga
This paper deals with the generation and implementation of a parallel algorithm for adaptive mesh refinement in 2D. This is an application in C and GTK that allows to construct the constrained Delaunay triangulation over an input polygon and the parallel refinement\\/unrefinement - local\\/global of the triangular mesh based on the longest edge bisection algorithm. The parallel refinement uses the
A scanning-mode 2D shear wave imaging (s2D-SWI) system for ultrasound elastography.
Qiu, Weibao; Wang, Congzhi; Li, Yongchuan; Zhou, Juan; Yang, Ge; Xiao, Yang; Feng, Ge; Jin, Qiaofeng; Mu, Peitian; Qian, Ming; Zheng, Hairong
2015-09-01
Ultrasound elastography is widely used for the non-invasive measurement of tissue elasticity properties. Shear wave imaging (SWI) is a quantitative method for assessing tissue stiffness. SWI has been demonstrated to be less operator dependent than quasi-static elastography, and has the ability to acquire quantitative elasticity information in contrast with acoustic radiation force impulse (ARFI) imaging. However, traditional SWI implementations cannot acquire two dimensional (2D) quantitative images of the tissue elasticity distribution. This study proposes and evaluates a scanning-mode 2D SWI (s2D-SWI) system. The hardware and image processing algorithms are presented in detail. Programmable devices are used to support flexible control of the system and the image processing algorithms. An analytic signal based cross-correlation method and a Radon transformation based shear wave speed determination method are proposed, which can be implemented using parallel computation. Imaging of tissue mimicking phantoms, and in vitro, and in vivo imaging test are conducted to demonstrate the performance of the proposed system. The s2D-SWI system represents a new choice for the quantitative mapping of tissue elasticity, and has great potential for implementation in commercial ultrasound scanners. PMID:26025508
Panserat, S; Sica, L; Gérard, N; Mathieu, H; Jacqz-Aigrain, E; Krishnamoorthy, R
1999-01-01
Aims To determine the molecular basis of the intermediate extensive metaboliser (EM) CYP2D6 phenotype in healthy Gabonese subjects. Methods The CYP2D6 phenotype of 154 healthy Gabonese subjects was assessed by giving the subject a single dose of 30 mg dextromethorphan, and collecting their urine for the next 8 h. The CYP2D6 genotype was determined for 50 individuals of the EM phenotypic group by Southern blotting and various PCR-based procedures aimed at identifying different CYP2D6 alleles. Results We found that in the studied Gabonese population, as compared with a French population, there is significantly higher frequency of intermediate EM phenotype having lower frequency of CYP2D6 PM alleles. To clarify this discrepancy phenotype-genotype relationship was studied. We found that the CYP2D6*17 and CYP2D6*2 alleles, prevalent in this black population, are characterised by their low capacity for dextromethorphan demethylation. Our data also show that the CYP2D6*1 allele is associated with the highest in vivo activity followed by the CYP2D6*2 allele and then the CYP2D6*17 allele. Conclusions The higher frequencies of the CYP2D6*2 and CYP2D6*17 alleles than the CYP2D6*1 allele account for the high frequency of the intermediate EM phenotype in this black population. The polymorphism of the CYP2D6 enzyme activity in African populations could have important implications for use of drugs that are substrates for CYP2D6 and have a narrow therapeutic window. PMID:10073750
Titan 2D: Understanding Titan’s Seasonal Atmospheric Cycles
NASA Astrophysics Data System (ADS)
Wong, Michael; Zhang, X.; Li, C.; Hu, R.; Shia, R.; Newman, C.; Müller-Wodarg, I.; Yung, Y.
2013-10-01
In this study, we present results from a novel two-dimensional (2D) model that simulates the physics and chemistry of Titan’s atmosphere. Despite being an icy moon of Saturn, Titan is the only Solar System object aside from Earth that is sheathed by a thick nitrogen-dominated atmosphere. This vulnerable gaseous envelope—an embodiment of a delicate coupling between photochemistry, radiation, and dynamics—is Nature’s laboratory for the synthesis of complex organic molecules. Titan’s large obliquity generates pronounced seasonal cycles in its atmosphere, and the Cassini spacecraft has been observing these variations since 2004. In particular, Cassini measurements show that the latitudinal distribution of Titan’s rich mélange of hydrocarbon species follows seasonal patterns. The mixing ratios of hydrocarbons increase with latitude towards the winter pole, suggesting a pole-to-pole circulation that reverses after equinox. Using a one-dimensional photochemical model of Titan’s atmosphere, we show that photochemistry alone cannot produce the observed meridional hydrocarbon distribution. This necessitates the employment of a 2D chemistry-transport model that includes meridional circulation as well as diffusive processes and photochemistry. Of additional concern, no previous 2D model of Titan extends beyond 500 km altitude—a critical limitation since the peak of methane photolysis is at 800 km. Our 2D model is the first to include Titan’s stratosphere, mesosphere, and thermosphere. The meridional circulation in our 2D model is derived from the outputs of two general circulation models (GCMs): the TitanWRF GCM (Newman et al. 2011) covering the troposphere, stratosphere, and lower mesosphere, and a thermosphere general circulation model (TGCM) covering the remainder of the atmosphere through the thermosphere (Müller-Wodarg et al. 2003; 2008). This presentation will focus on the utilization of these advances applied to the 2D Caltech/JPL KINETICS model to understand the seasonal and meridional distribution of hydrocarbons as well as other atmospheric cycles on Titan.
Integral Geometry and Holography
Czech, Bartlomiej; McCandlish, Samuel; Sully, James
2015-01-01
We present a mathematical framework which underlies the connection between information theory and the bulk spacetime in the AdS$_3$/CFT$_2$ correspondence. A key concept is kinematic space: an auxiliary Lorentzian geometry whose metric is defined in terms of conditional mutual informations and which organizes the entanglement pattern of a CFT state. When the field theory has a holographic dual obeying the Ryu-Takayanagi proposal, kinematic space has a direct geometric meaning: it is the space of bulk geodesics studied in integral geometry. Lengths of bulk curves are computed by kinematic volumes, giving a precise entropic interpretation of the length of any bulk curve. We explain how basic geometric concepts -- points, distances and angles -- are reflected in kinematic space, allowing one to reconstruct a large class of spatial bulk geometries from boundary entanglement entropies. In this way, kinematic space translates between information theoretic and geometric descriptions of a CFT state. As an example, we...
NSDL National Science Digital Library
Eppstein, David
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).
Euclidean geometry as algorithm for construction of generalized geometries
Yuri A. Rylov
2005-11-23
It is shown that the generalized geometries may be obtained as a deformation of the proper Euclidean geometry. Algorithm of construction of any proposition S of the proper Euclidean geometry E may be described in terms of the Euclidean world function sigma_E in the form S(sigma_E). Replacing the Euclidean world function sigma_E by the world function sigma of the geometry G, one obtains the corresponding proposition S(sigma) of the generalized geometry G. Such a construction of the generalized geometries (known as T-geometries) uses well known algorithms of the proper Euclidean geometry and nothing besides. This method of the geometry construction is very simple and effective. Using T-geometry as the space-time geometry, one can construct the deterministic space-time geometries with primordially stochastic motion of free particles and geometrized particle mass. Such a space-time geometry defined properly (with quantum constant as an attribute of geometry) allows one to explain quantum effects as a result of the statistical description of the stochastic particle motion (without a use of quantum principles).
Visible light stealth based on 2D holographic antireflection coatings
NASA Astrophysics Data System (ADS)
Liu, Ying; Yao, Guozheng; Zhao, Lili
2014-11-01
The reflection efficiency of material surface can be reduced by fabricated sub-micron periodic structures. Part of the light energy will propagate along the surface of the material as guided wave, thereby, the interaction between material and light is increased and the light absorption efficiency in visible light stealth material is improved. In this paper, two-dimensional (2D) relief periodic structure with 300nm was fabricated by holographic lithography. Test results show that the reflection efficiency of the material surface can be reduce after fabricated 2D periodic structures. However, because of the presence of diffraction orders, the zero order transmission diffraction efficiency is reduced in short wavelength band. Through rational design of the duty cycle and etching depth, the diffraction efficiency of reflection can be reduced, and then, the optical coupling efficiency of the material can be improved and the visible light stealth properties of the material can be improved too.
A "Necklace" Model for Vesicles Simulations in 2D
Mourad Ismail; Aline Lefebvre-Lepot
2012-02-14
The aim of this paper is to propose a new numerical model to simulate 2D vesicles interacting with a newtonian fluid. The inextensible membrane is modeled by a chain of circular rigid particles which are maintained in cohesion by using two different type of forces. First, a spring force is imposed between neighboring particles in the chain. Second, in order to model the bending of the membrane, each triplet of successive particles is submitted to an angular force. Numerical simulations of vesicles in shear flow have been run using Finite Element Method and the FreeFem++[1] software. Exploring different ratios of inner and outer viscosities, we recover the well known "Tank-Treading" and "Tumbling" motions predicted by theory and experiments. Moreover, for the first time, 2D simulations of the "Vacillating-Breathing" regime predicted by theory in [2] and observed experimentally in [3] are done without special ingredient like for example thermal fluctuations used in [4].
F2D: A two dimensional compressible gas flow code
Ahti Suo-Anttila (Science Applications International Corporation, 2109 Air Park Road S.E., Albuquerque, New Mexico 87106 (United States))
1993-01-20
The F2D computer code is a general-purpose, two-dimensional, fully compressible thermal-fluids code that models most phenomena found in experimental environments with coupled fluid flow and heat transfer. The code solves momentum, continuity, gas energy, and structure energy equations, simultaneously utilizing a predictor-corrector solution algorithm. The F2D code applied to a particle-bed reactor operating at 5 MW/L with a flow-control cold frit, revealed a skew in the temperature contours caused by two-dimensional flow effects. A thermal-fluid stability analysis of particle-bed and NERVA type reactors reveals similar behavior for the stability threshold.
F2D: A two dimensional compressible gas flow code
NASA Astrophysics Data System (ADS)
Ahti, Suo-Anttila
1993-01-01
The F2D computer code is a general-purpose, two-dimensional, fully compressible thermal-fluids code that models most phenomena found in experimental environments with coupled fluid flow and heat transfer. The code solves momentum, continuity, gas energy, and structure energy equations, simultaneously utilizing a predictor-corrector solution algorithm. The F2D code applied to a particle-bed reactor operating at 5 MW/L with a flow-control cold frit, revealed a skew in the temperature contours caused by two-dimensional flow effects. A thermal-fluid stability analysis of particle-bed and NERVA type reactors reveals similar behavior for the stability threshold.
Defect Dynamics in Active 2D Nematic Liquid Crystals
NASA Astrophysics Data System (ADS)
Decamp, Stephen; Redner, Gabriel; Hagan, Michael; Dogic, Zvonimir
2014-03-01
Active materials are assemblies of animate, energy-consuming objects that exhibit continuous dynamics. As such, they have properties that are dramatically different from those found in conventional materials made of inanimate objects. We present a 2D active nematic liquid crystal composed of bundled microtubules and kinesin motor proteins that exists in a dynamic steady-state far from equilibrium. The active nematic exhibits spontaneous binding and unbinding of charge +1/2 and -1/2 disclination defects as well as streaming of +1/2 defects. By tuning ATP concentration, we precisely control the amount of activity, a key parameter of the system. We characterize the dynamics of streaming defects on a large, flat, 2D interface using quantitative polarization light microscopy. We report fundamental characteristics of the active nematics such as defect velocities, defect creation and annihilation rates, and emergent length scales in the system.
Electronic and magnetic properties of 2D BCN nanostructures
NASA Astrophysics Data System (ADS)
Park, Hyoungki
2013-03-01
Recent developments of two-dimensional (2D) nanomaterials hold great promises for future electronics, optics and spintronics. Since the isolation and electronic characterization of graphene, other layered 2D crystals also have been synthesized. In particular, carbon can be combined with its neighboring atoms in the periodic table, boron and nitrogen as hexagonal BN (h-BN), to obtain hybrid BCN configurations. These BCN 2D nanostructures show a rich variety of physical properties, distinct from parent materials. Their electronic properties can in principle be tuned by varying the concentration of each of the three elements. We study electronic structures of a variety of 2D BCN nanostructures using hybrid functional HSE in density functional theory (DFT). We show that their electronic properties can be gradually tuned by composition and the atomic configuration of three elements. We demonstrate that the substitution-induced impurity states, associated with carbon atoms, and their interactions dictate the electronic structure and properties of C-doped h-BN. Stacking of localized impurity states in small C clusters embedded in h-BN forms a set of discrete energy levels in the wide gap of h-BN, leading to electronic structures of quantum dots made of carbon nano-domains for applications in optics and opto-electronics. We also show that half-metallic electron transport can be achieved by low concentration substitutional doping of only one sublattice of graphene by nitrogen or boron atoms. The delocalized spin-densities induced by the unpaired electrons at substitutional sites permeate only through the sublattice where the nitrogen (boron) atoms belong. For interacting nitrogen (boron) atoms located along the ``zigzag'' direction and in the same sublattice the ferro-magnetic spin-ordering is energetically favored, and substitution-induced impurity states selectively disturb the spin-polarized ?-orbital of that same sublattice. Recent developments of two-dimensional (2D) nanomaterials hold great promises for future electronics, optics and spintronics. Since the isolation and electronic characterization of graphene, other layered 2D crystals also have been synthesized. In particular, carbon can be combined with its neighboring atoms in the periodic table, boron and nitrogen as hexagonal BN (h-BN), to obtain hybrid BCN configurations. These BCN 2D nanostructures show a rich variety of physical properties, distinct from parent materials. Their electronic properties can in principle be tuned by varying the concentration of each of the three elements. We study electronic structures of a variety of 2D BCN nanostructures using hybrid functional HSE in density functional theory (DFT). We show that their electronic properties can be gradually tuned by composition and the atomic configuration of three elements. We demonstrate that the substitution-induced impurity states, associated with carbon atoms, and their interactions dictate the electronic structure and properties of C-doped h-BN. Stacking of localized impurity states in small C clusters embedded in h-BN forms a set of discrete energy levels in the wide gap of h-BN, leading to electronic structures of quantum dots made of carbon nano-domains for applications in optics and opto-electronics. We also show that half-metallic electron transport can be achieved by low concentration substitutional doping of only one sublattice of graphene by nitrogen or boron atoms. The delocalized spin-densities induced by the unpaired electrons at substitutional sites permeate only through the sublattice where the nitrogen (boron) atoms belong. For interacting nitrogen (boron) atoms located along the ``zigzag'' direction and in the same sublattice the ferro-magnetic spin-ordering is energetically favored, and substitution-induced impurity states selectively disturb the spin-polarized ?-orbital of that same sublattice. Supported by DOE-Basic Energy Science DOE-BES-DMS (DEFG02-99ER45795). Computing resources are provided by NERSC and OSC.
Implementation of 2-D DCT based on FPGA
NASA Astrophysics Data System (ADS)
Guo, Bao-Zeng; Niu, Li; Liu, Zhi-Ming
2010-08-01
Discrete Cosine Transform (DCT) plays an important role in the image and video compression, and it has been widely used in JPEG, MPEG, H.26x. DCT being implemented by hardware is crucial to improve the speed of image compression. This paper presents a method that 2-D DCT is implemented by FPGA, which is based on the algorithm of row-column decomposition, and the parallel structure is used to achieve high throughput. The design is achieved by top-down design methodology and described with Verilog HDL in RTL level. The hardware of 2-D DCT is implemented by the FPGA EP2C35F672C8 made by ALTERA. The experiment results show that the delay time is as low as 15 ns, and the clock frequency as high as 138.35 MHz, which can satisfy the requirements of the real-time video image compression.
2-D Magnetohydrodynamic Modeling of A Pulsed Plasma Thruster
NASA Technical Reports Server (NTRS)
Thio, Y. C. Francis; Cassibry, J. T.; Wu, S. T.; Rodgers, Stephen L. (Technical Monitor)
2002-01-01
Experiments are being performed on the NASA Marshall Space Flight Center (MSFC) MK-1 pulsed plasma thruster. Data produced from the experiments provide an opportunity to further understand the plasma dynamics in these thrusters via detailed computational modeling. The detailed and accurate understanding of the plasma dynamics in these devices holds the key towards extending their capabilities in a number of applications, including their applications as high power (greater than 1 MW) thrusters, and their use for producing high-velocity, uniform plasma jets for experimental purposes. For this study, the 2-D MHD modeling code, MACH2, is used to provide detailed interpretation of the experimental data. At the same time, a 0-D physics model of the plasma initial phase is developed to guide our 2-D modeling studies.
Transition to chaos in an open unforced 2D flow
NASA Technical Reports Server (NTRS)
Pulliam, Thomas H.; Vastano, John A.
1993-01-01
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.
Structural analysis of teicoplanin A2 by 2d NMR
NASA Astrophysics Data System (ADS)
Heald, Sarah L.; Mueller, Luciano; Jeffs, Peter W.
The analysis of the intact glycopeptide antibiotic, teicoplanin A 2, by two-dimensional proton NMR is described. Delayed-correlation spectroscopy (COSY), double-quantum coherence experiments (DACE), and nuclear Overhauser spectroscopy (NOESY) are utilized to confirm the primary structure. Distance constraints derived from NOESY data integrated with computer-assisted molecular modeling and force-field energy minimization yields a proposed three-dimensional solution-state conformation. Included are NMR methods developed for improved accuracy of distance measurements from 2D NOE experiments obtained on samples dissolved in DMSO- d6/water. The effects of different pulse sequences for water suppression on the 2D NOE spectral results are compared. Clear indication that teicoplanin exists in two unequally populated conformations which are in slow exchange is revealed by the presence of cross peaks attributable to conformational interchange in the NOESY spectra.
Formation of hybrid 2D polymer-metal microobjects.
Comrie, Jean E; Huck, Wilhelm T S
2007-01-30
This paper describes a fabrication strategy based on polymer brushes (20-150 nm thick) and soft lithographic techniques, for creating hydrophobic, cross-linked, laterally patterned polymer films. The hydrophobicity of the resulting micrometer-scale "quasi-2D" objects is shown to allow the polymer to act as an etch resist. By adjusting the etching time, we demonstrate that underetching of the gold from underneath the edges of the laterally patterned films can be used to create free-standing polymer-gold hybrid structures. These structures retain their structural integrity when lifted wholly or partially from the substrate and can hence be imaged in suspension. Characterization of the quasi-2D objects was carried out using atomic force microscopy (AFM), ellipsometry, optical microscopy, and Fourier transform infrared spectroscopy (FTIR). A continuous film, containing embedded polymer-gold objects, can be lifted, folded, and re-deposited onto a substrate without damaging the conductivity of the embedded metallic objects. PMID:17241089
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
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
Evaluation of imaging geometry for stationary chest tomosynthesis
NASA Astrophysics Data System (ADS)
Shan, Jing; Tucker, Andrew W.; Lee, Yueh Z.; Heath, Michael D.; Wang, Xiaohui; Foos, David; Lu, Jianping; Zhou, Otto
2014-03-01
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.
Feature based 3D garment design through 2D sketches
Charlie C. L. Wang; Yu Wang; Matthew Ming-fai Yuen
2003-01-01
This paper presents a new approach for intuitively modeling a 3D garment around a 3D human model by 2D sketches input. Our approach is feature based - every human model has pre-defined features, and the constructed garments are related to the features on human models. Firstly, a feature template for creating a customized 3D garment is defined according to the
Local topological order inhibits thermal stability in 2D
Olivier Landon-Cardinal; David Poulin
2012-09-25
We study the robustness of quantum information stored in the degenerate ground space of a local, frustration-free Hamiltonian with commuting terms on a 2D spin lattice. On one hand, a macroscopic energy barrier separating the distinct ground states under local transformations would protect the information from thermal fluctuations. On the other hand, local topological order would shield the ground space from static perturbations. Here we demonstrate that local topological order implies a constant energy barrier, thus inhibiting thermal stability.
A Tied-Mixture 2-D HMM Face Recognition System
Hisham Othman; Tyseer Aboulnasr
2002-01-01
In this paper, a simplified 2D second-order hidden Markov model (HMM) with tied state mixtures is applied to the face recognition problem. The mixture of the model states is fully-tied across all models for lower complexity. Tying HMM parameters is a well-known solution for the problem of insufficient training data leading to nonrobust estimation. We show that parameter tying in
Design and optimization of 2D electrostatic micro scanning mirrors
Jun Yao; Wenying Ma; Fangrong Hu; Dongmei Cai; Dajia Wang; Chuankai Qiu
2009-01-01
is paper demonstrates a 2D (two-dimensional) electrostatic MEMS scanning mirror. This scanner rotates on both axis X and Y, giving a two degrees of freedom. Finite element analysis has shown that optical scanning angle on axis X is 5.0° at 120V and axis Y is 4.4°at 160V. The structure has been optimized to achieve good dynamic performance.
A 2-D MSGC-based imaging detector for neutrons
J. E. Bateman; G. E. Derbyshire; D. M. Duxbury; A. S. Marsh; N. J. Rhodes; E. M. Schooneveld; E. J. Spill; R. Stephenson
2005-01-01
The development and testing of a two-dimensional (2-D) prototype detector based on a microstrip gas chamber (MSGC) is reported using a gas mixture of 2.5 bar 3He and 2.5 bar CF4. The second coordinate is obtained by utilising a plane of wires as pick up electrodes. The detector is operated with the wire plane at such a potential so as
Supramolecular assembly of heterocirculenes in 2D and 3D.
Ivasenko, Oleksandr; Macleod, Jennifer M; Chernichenko, Konstantin Yu; Balenkova, Elizabeth S; Shpanchenko, Roman V; Nenajdenko, Valentine G; Rosei, Federico; Perepichka, Dmitrii F
2009-03-14
The results of a high-resolution ambient STM study of 'sulflower' (octathio[8]circulene) and 'selenosulflower' (sym-tetraselena-tetrathio[8]circulene) molecules, immobilized in a hydrogen-bonded matrix of trimesic acid (TMA) at the solid-liquid interface, are compared with the STM and X-ray structure of separate host and guest 2D and 3D crystals, respectively. PMID:19240870
Report of the 1988 2-D Intercomparison Workshop, chapter 3
NASA Technical Reports Server (NTRS)
Jackman, Charles H.; Brasseur, Guy; Soloman, Susan; Guthrie, Paul D.; Garcia, Rolando; Yung, Yuk L.; Gray, Lesley J.; Tung, K. K.; Ko, Malcolm K. W.; Isaken, Ivar
1989-01-01
Several factors contribute to the errors encountered. With the exception of the line-by-line model, all of the models employ simplifying assumptions that place fundamental limits on their accuracy and range of validity. For example, all 2-D modeling groups use the diffusivity factor approximation. This approximation produces little error in tropospheric H2O and CO2 cooling rates, but can produce significant errors in CO2 and O3 cooling rates at the stratopause. All models suffer from fundamental uncertainties in shapes and strengths of spectral lines. Thermal flux algorithms being used in 2-D tracer tranport models produce cooling rates that differ by as much as 40 percent for the same input model atmosphere. Disagreements of this magnitude are important since the thermal cooling rates must be subtracted from the almost-equal solar heating rates to derive the net radiative heating rates and the 2-D model diabatic circulation. For much of the annual cycle, the net radiative heating rates are comparable in magnitude to the cooling rate differences described. Many of the models underestimate the cooling rates in the middle and lower stratosphere. The consequences of these errors for the net heating rates and the diabatic circulation will depend on their meridional structure, which was not tested here. Other models underestimate the cooling near 1 mbar. Suchs errors pose potential problems for future interactive ozone assessment studies, since they could produce artificially-high temperatures and increased O3 destruction at these levels. These concerns suggest that a great deal of work is needed to improve the performance of thermal cooling rate algorithms used in the 2-D tracer transport models.
3-D Object Recognition Using 2-D Views
Wenjing Li; George Bebis; Nikolaos G. Bourbakis
2008-01-01
We consider the problem of recognizing 3-D objects from 2-D images using geometric models and assuming different viewing angles and positions. Our goal is to recognize and localize instances of specific objects (i.e., model-based) in a scene. This is in contrast to category-based object recognition methods where the goal is to search for instances of objects that belong to a
Smart multi-sensor for 2D target classification
Heinrich Ruser; Boris Ivanov; Michael Horn
2003-01-01
A multi-sensor for the detection and classification of objects in indoor environments, merging the outputs from an infrared (IR) diode array and an ultrasonic (US) range sensor to get a reliable 2D image of objects in front of the sensor, is described. With the IR sensor array consisting of up to 8 emitter-receiver pairs, multiple objects can be detected and
1092 Channel 2-D Array Demultiplexer for Ultralarge Data Bandwidth
Trevor K. Chan; Jason Karp; Rui Jiang; Nikola Alic; Stojan Radic; Christopher F. Marki; Joseph E. Ford
2007-01-01
We demonstrate 1 times 1092 channel wavelength demultiplexing with 50-GHz channel pitch and a 600-nm total bandwidth. Outputs from 1 times 40 channel arrayed waveguide gratings operating with multiple orders enter a free-space optical grating demultiplexer which separates the orders into a 2-D spot array, where the light can be coupled into discrete output fibers or operated on by a
Translating 2D German expressionist woodcut artwork into 3D
Musha, Elona
2006-10-30
&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved by: Chair of Committee, Karen Hillier Committee Members, Carol LaFayette Michael Greenwald Head of Department, Mardelle Shepley... August 2006 Major Subject: Visualization Sciences iii ABSTRACT Translating 2D German Expressionist Woodcut Artwork Into 3D. (August 2006) Elona Musha, B.F.A., Shawnee State University Chair of Advisory Committee: Prof. Karen Hillier...
NASA High-Speed 2D Photogrammetric Measurement System
NASA Technical Reports Server (NTRS)
Dismond, Harriett R.
2012-01-01
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.
Theoretical and computational aspects of 2-D inverse profiling
Anton G. Tijhuis; Kamal Belkebir; Amélie C. S. Litman; Bastiaan P. de Hon
2001-01-01
The authors discuss two techniques for solving two-dimensional (2D) inverse scattering problems by parameterizing the scattering configuration, and determining the optimum value of the parameters by minimizing a cost function involving the known scattered-field data. The computation of the fields in each estimated configuration is considered as an auxiliary problem. To improve the efficiency of these computations, the CGFFT iterative
Remark on numerical simulation of 2D unsteady transonic flows
NASA Astrophysics Data System (ADS)
Fo?t, J.; Hülek, T.; Kozel, K.; Vavrincová, M.
The work deals with three numerical methods solving the system of Euler or Navier-Stokes equations. Mac Cormack cell centered and Ni cell vertex finite volume schemes were used for simulation of inviscid unsteady solution of transonic flows through a 2D cascade. Unsteady motion is caused by a periodic change of downstream pressure. The Runge-Kutta multistage cell centered finite volume scheme has been used for viscous laminar steady and unsteady transonic flows over NACA 0012.
3D structures by 2D vibrational spectroscopy
Remorino, Amanda; Hochstrasser, Robin M.
2012-01-01
Conspectus The development of experiments that can generate molecular movies of changing chemical structures is a major challenge for physical chemistry. But to realize this dream, we not only need to significantly improve existing approaches, but we also must invent new technologies .. Most of the known protein structures have been determined by X-ray diffraction and to lesser extent by NMR. Though powerful, X-ray diffraction presents limitations for acquiring time dependent structures. In the case of NMR, ultrafast equilibrium dynamics might be inferred from lineshapes, but the structures of conformations interconverting on such time scales are not realizable. This Account highlights two dimensional infrared spectroscopy (2D IR), in particular the 2D vibrational echo, as an approach to time resolved structure determination. We outline the use of the 2D IR method to completely determine the structure of a protein of the integrin family in a time window of few picoseconds. As a transmembrane protein, this class of structures has proved particularly challenging for the established structural methodologies of x-ray crystallography and NMR. We describe the challenges facing multidimensional spectroscopy and compare it with some other methods of structural biology. Then we succinctly discuss the basic principles of 2D IR methods as they relate to time domain and frequency domain experimental and theoretical properties required for protein structure determination. By means of the example of the transmembrane protein, we describe the essential aspects of combined carbon-13 oxygen-18 isotope labels to create vibrational resonance pairs that allow the determination of protein and peptide structures in motion. Finally, we propose a three dimensional structure of the ?IIb transmembrane homodimer that includes optimum locations of all side chains and backbone atoms of the protein. Delocalization among 13C=18O residues on different helices. The vibrational excitation is transferred between modes on different helices on the coherent energy transfer time ?/2?. PMID:22458539
Baby universes and fractal structure of 2d gravity
NASA Astrophysics Data System (ADS)
Thorleifsson, Gudmar
1994-04-01
We extract the string susceptibility exponent ?str by measuring the distribution of baby universes on surfaces in the case of various matter fields coupled to discrete 2d quantum gravity. For c <= 1 the results are in good agreement with the KPZ-formula, if logarithmic corrections are taken into account for c = 1. For c > 1 it is not as clear how to extract ?str but universality with respect to c is observed in the fractal structure.
Analyses of the 2dF Deep Field
NASA Astrophysics Data System (ADS)
Fulton, Chris; Arp, Halton; Hartnett, John G.
2010-06-01
We briefly discuss the observational motivation for and then present statistical analyses performed by a computer algorithm on the 2dF deep field. The results show that high redshift extragalactic objects can be and in many cases are physically associated with low redshift extragalactic objects and that consequently these high redshifts are at least partly intrinsic and therefore not entirely due to Doppler shift.
Stabilization and extraction of 2D barcodes for camera phones
Chung-Hua Chu; De-Nian Yang; Ya-Lan Pan; Ming-Syan Chen
2011-01-01
With the ubiquity of cellular phones, mobile applications with 2D barcodes have drawn a lot of attentions in recent years.\\u000a When a user takes a barcode image with the camera in a mobile device, the captured image tends to be blurred due to camera\\u000a shaking when the user presses the shutter. In addition, the captured image includes part of the
CHARACTERISTIC VIEWS: OBTAINING 2-D RECONSTRUCTIONS FROM COLOR EDGES
G. Bellaire; K. Talmi; E. Oezguer; A. Koschan
This article presents a complete hybrid object recognition system for three-dimensional objects using the characteristic view (ChV) idea. High-quality 2-D reconstructions have to be generated from intensity or color data, respectively, to integrate the ChV represen- tation method into a recognition system. First, we present an approach for obtaining edges and gradient information from color images. Second, we present an
Analog integrated 2-D optical flow sensor with programmable pixels
Alan A. Stocker; Rodney J. Douglas
2004-01-01
We present a framework for real-time visual motion per- ception consisting of a novel analog VLSI optical flow sen- sor with reconfigurablepixels, connectedin feedbackwith a controlling processor. The 2-D sensor array is composed of motion processing pixels that can be individually recruited to form dynamicensembles that collectively computevisual motion. This flexible framework lends itself to the emula- tion of multi-layer
Quenching of O+/2D/ by electrons in the thermosphere
NASA Technical Reports Server (NTRS)
Torr, M. R.; Torr, D. G.; Richards, P.
1980-01-01
Satellite measurements of relevant ionospheric parameters were used to determine the rate coefficient for quenching of O+(2D) by electrons as a function of temperature. The results agree with the theoretically determined rate coefficient to within statistical uncertainties. The study provides confirmation of the absolute magnitude of the rate coefficient given by theoretical calculation at these temperatures, but it also indicates a somewhat steeper dependence on electron temperature than that predicted by theory.
Strings in a 2-d Extremal Black Hole
Amit Giveon; Amit Sever
2005-01-01
String theory on 2-d charged black holes corresponding to (SL(2) × U(1)L)\\/U(1) exact asymmetric quotient CFTs are investigated. These backgrounds can be embedded, in particular, in a two dimensional heterotic string. In the extremal case, the quotient CFT description captures the near horizon physics, and is equivalent to strings in AdS2 with a gauge field. Such string vacua possess an
Bi-Hamiltonian Structure in 2-d Field Theory
E. V. Ferapontov; C. A. P. Galvăo; O. I. Mokhov; Y. Nutku
1997-01-01
: We exhibit the bi-Hamiltonian structure of the equations of associativity (Witten-Dijkgraaf-Verlinde-Verlinde-Dubrovin equations)\\u000a in 2-d topological field theory, which reduce to a single equation of Monge-Amp?re type in the case of three primary fields. The first Hamiltonian structure of this equation is based on its representation as a\\u000a 3-component system of hydrodynamic type and the second Hamiltonian structure follows from its
Application of 2D Barcode in Hardcopy Document Verification System
Mazleena Salleh; Teoh Chin Yew
2009-01-01
Forgery can cause significant damage in terms of trust and authenticity. Therefore, it is essential that the integrity of\\u000a important documents should be maintained to avoid implication of the document being jeopardized by criminals. In this study\\u000a we explore the applicability of two-dimensional (2D) barcode, specifically Data Matrix Barcode, for the integrity verification\\u000a of hardcopy documents. The proposed system also
Building 3D scenes from 2D image sequences
NASA Astrophysics Data System (ADS)
Cristea, Paul D.
2006-05-01
Sequences of 2D images, taken by a single moving video receptor, can be fused to generate a 3D representation. This dynamic stereopsis exists in birds and reptiles, whereas the static binocular stereopsis is common in mammals, including humans. Most multimedia computer vision systems for stereo image capture, transmission, processing, storage and retrieval are based on the concept of binocularity. As a consequence, their main goal is to acquire, conserve and enhance pairs of 2D images able to generate a 3D visual perception in a human observer. Stereo vision in birds is based on the fusion of images captured by each eye, with previously acquired and memorized images from the same eye. The process goes on simultaneously and conjointly for both eyes and generates an almost complete all-around visual field. As a consequence, the baseline distance is no longer fixed, as in the case of binocular 3D view, but adjustable in accordance with the distance to the object of main interest, allowing a controllable depth effect. Moreover, the synthesized 3D scene can have a better resolution than each individual 2D image in the sequence. Compression of 3D scenes can be achieved, and stereo transmissions with lower bandwidth requirements can be developed.
A 2D model for a gliding arc discharge
NASA Astrophysics Data System (ADS)
Kolev, St.; Bogaerts, A.
2015-02-01
In this study we report on a 2D fluid model of a gliding arc discharge in argon. Despite the 3D nature of the discharge, 2D models are found to be capable of providing very useful information about the operation of the discharge. We employ two models—an axisymmetric and a Cartesian one. We show that for the considered experiment and the conditions of a low current arc (around 30 mA) in argon, there is no significant heating of the cathode surface and the discharge is sustained by field electron emission from the cathode accompanied by the formation of a cathode spot. The obtained discharge power and voltage are relatively sensitive to the surface properties and particularly to the surface roughness, causing effectively an amplification of the normal electric field. The arc body and anode region are not influenced by this and depend mainly on the current value. The gliding of the arc is modelled by means of a 2D Cartesian model. The arc–electrode contact points are analysed and the gliding mechanism along the electrode surface is discussed. Following experimental observations, the cathode spot is simulated as jumping from one point to another. A complete arc cycle is modelled from initial ignition to arc decay. The results show that there is no interaction between the successive gliding arcs.
Region-based Statistical Analysis of 2D PAGE Images
Li, Feng; Seillier-Moiseiwitsch, Françoise; Korostyshevskiy, Valeriy R.
2011-01-01
A new comprehensive procedure for statistical analysis of two-dimensional polyacrylamide gel electrophoresis (2D PAGE) images is proposed, including protein region quantification, normalization and statistical analysis. Protein regions are defined by the master watershed map that is obtained from the mean gel. By working with these protein regions, the approach bypasses the current bottleneck in the analysis of 2D PAGE images: it does not require spot matching. Background correction is implemented in each protein region by local segmentation. Two-dimensional locally weighted smoothing (LOESS) is proposed to remove any systematic bias after quantification of protein regions. Proteins are separated into mutually independent sets based on detected correlations, and a multivariate analysis is used on each set to detect the group effect. A strategy for multiple hypothesis testing based on this multivariate approach combined with the usual Benjamini-Hochberg FDR procedure is formulated and applied to the differential analysis of 2D PAGE images. Each step in the analytical protocol is shown by using an actual dataset. The effectiveness of the proposed methodology is shown using simulated gels in comparison with the commercial software packages PDQuest and Dymension. We also introduce a new procedure for simulating gel images. PMID:21850152
Characterization of Porous Medium Properties Using 2D NMR
NASA Astrophysics Data System (ADS)
Sun, Boqin; Dunn, Keh-Jim
2003-03-01
We have successfully applied the concept of 2D NMR to the characterization of properties of fluid-saturated porous medium. Using a two-windowed modified CPMG pulse sequence, we were able to explore the magnetic internal filed gradient distribution within the pore space of a fluid-saturated porous medium due to magnetic susceptibility contrast between the solid matrix and pore fluid. Similar scheme is used to identify and quantify different types of pore fluids, such as oil, water, and gas, based on the contrast in their diffusion coefficients. The magic angle spinning technique (MAS) can also be applied in the 2D NMR framework for delineating the chemical shift spectra of the pore fluids in a porous medium at different T1 or T2 relaxation times. The results can be displayed in a two-dimensional plot, with one axis being the T1 or T2 relaxation times, the other axis being the internal field gradient, diffusion coefficient, or chemical shift, and the third axis being the proton population. Our preliminary laboratory work indicates that the 2D NMR approach can be a powerful tool for the characterization of properties of fluid-saturated porous medium, such as fluid typing, oil viscosity determination, surface wettability, etc.
Volumetric Elasticity Imaging with a 2D CMUT Array
Fisher, Ted G.; Hall, Timothy J.; Panda, Satchi; Richards, Michael S.; Barbone, Paul E.; Jiang, Jingfeng; Resnick, Jeff; Barnes, Steve
2010-01-01
This paper reports the use of a two-dimensional (2D) capacitive micro-machined ultrasound transducer (CMUT) to acquire radio frequency (RF) echo data from relatively large volumes of a simple ultrasound phantom to compare 3D elasticity imaging methods. Typical 2D motion tracking for elasticity image formation was compared to three different methods of 3D motion tracking, with sum-squared difference (SSD) used as the similarity measure. Differences among the algorithms were the degree to which they tracked elevational motion: not at all (2D search), planar search, combination of multiple planes, and plane independent guided search. The cross correlation between the pre-deformation and motion-compensated post-deformation RF echo fields was used to quantify motion tracking accuracy. The lesion contrast-to-noise ratio was used to quantify image quality. Tracking accuracy and strain image quality generally improved with increased tracking sophistication. When used as input for a 3D modulus reconstruction, high quality 3D displacement estimates yielded accurate and low noise modulus reconstruction. PMID:20510188
High precision calibration for 2D optical standard
NASA Astrophysics Data System (ADS)
Sun, Shuanghua; Gan, Xiaochuan; Xue, Zi; Ye, Xiaoyou; Wang, Heyan; Gao, Hongtang
2012-10-01
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).
COMBINING 2D AND 3D VIEWS FOR VISUALIZATION OF SPATIAL DATA
Zhang, Richard "Hao"
COMBINING 2D AND 3D VIEWS FOR VISUALIZATION OF SPATIAL DATA by Melanie Tory B.Sc. University Title of Thesis: Combining 2D and 3D Views for Visualization of Spatial Data Examining Committee compares two-dimensional (2D), three-dimensional (3D), and 2D/ 3D combination displays (orientation icon
IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS Visualization Task Performance with 2D, 3D,
Tory, Melanie
IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS Visualization Task Performance with 2D, 3D--We describe a series of experiments that compare 2D displays, 3D displays, and combined 2D/3D displays, orientation icon and ExoVis displays were better than strict 2D or 3D displays (displays consisting
Reasoning with Uncertain Points, Straight Lines, and Straight Line Segments in 2D
Reasoning with Uncertain Points, Straight Lines, and Straight Line Segments in 2D Jochen Meidow ,a representations of uncertain Preprint submitted to Elsevier 23 July 2009 #12;geometric entities in 2D together is necessary for efficient and successful spatial reasoning in 2D and 3D. Basic geometric 2D elements
Frydman, Lucio
Ultrafast 2D NMR Spectroscopy Using Sinusoidal Gradients: Principles and Ex Vivo Brain ultrafast acquisitions of 2D NMR spectra with suitable spectral widths on a microimaging probe (for both Wiley-Liss, Inc. Key words: ultrafast 2D NMR; magnetic resonance spectros- copy; brain metabolites; 2D
2D Mapping of Cluttered Indoor Environments by Means of 3D Perception
Arras, Kai O.
2D Mapping of Cluttered Indoor Environments by Means of 3D Perception Oliver Wulf 1 , Kai O. Arras presents a combination of a 3D laser sensor and a line-base SLAM algorithm which together produce 2D line of commonly used 2D laser range sensors by 3D perception. A straightforward algorithm extracts a virtual 2D
ERIC Educational Resources Information Center
KLIER, KATHERINE M.
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…
Sliding vane geometry turbines
Sun, Harold Huimin; Zhang, Jizhong; Hu, Liangjun; Hanna, Dave R
2014-12-30
Various systems and methods are described for a variable geometry turbine. In one example, a turbine nozzle comprises a central axis and a nozzle vane. The nozzle vane includes a stationary vane and a sliding vane. The sliding vane is positioned to slide in a direction substantially tangent to an inner circumference of the turbine nozzle and in contact with the stationary vane.
NSDL National Science Digital Library
Hardaker, Chris.
This Website, sprung from a gifted-and-talented program for K-12 students in Arizona, presents the interesting world of Native American geometry, a system based on the proportional relationship between the radius and circumference of a circle. The eye-pleasing site, divided into sections that include Foundations, Education, Designs, and Anthropology, would be appealing to curious Web surfers along with mathematics students. Geometric principles of proportions and angles are presented in the context of Native American designs, joining art and science and allowing students to learn in a creative, applied fashion. Some highlights of the site include illustrated examples of how corporate logos such as those of Mitsubishi or CBS Television are based on this geometry and a page on the architectural geometries of archaeologic sites such as Chaco Canyon, NM. A brief discussion of the history of circle-based ("string and two sticks") geometry throughout the world and a list of references for teachers are also important parts of this site.
Baldwin, John T.
's Critique Three Frameworks High School Curriculum http://www.glencoe.com/sec/math/studytools/cgi- binGeometry and Proof John T. Baldwin Hilbert's Critique Three Frameworks High School Curriculum Frameworks High School Curriculum Outline 1 Hilbert's Critique 2 Three Frameworks 3 High School Curriculum
NSDL National Science Digital Library
2010-01-01
This activity allows learners to practice observation skills and to realize examples of geometric shapes are everywhere. This geometry scavenger hunt (PDF) contains a set of directions and a recording sheet to complete. Included also is a list of materials and extension ideas.
ERIC Educational Resources Information Center
Martin, John
2010-01-01
The cycloid has been called the Helen of Geometry, not only because of its beautiful properties but also because of the quarrels it provoked between famous mathematicians of the 17th century. This article surveys the history of the cycloid and its importance in the development of the calculus.
ERIC Educational Resources Information Center
Hartz, Viggo
1981-01-01
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)
ERIC Educational Resources Information Center
MacKeown, P. K.
1984-01-01
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)
ERIC Educational Resources Information Center
Fielker, David
2007-01-01
Geoff Giles died suddenly in 2005. He was a highly original thinker in the field of geometry teaching. As early as 1964, when teaching at Strathallen School in Perth, he was writing in "MT27" about constructing tessellations by modifying the sides of triangles and (irregular) quadrilaterals to produce what he called "trisides" and "quadrisides".…
Duality and asymptotic geometries
Harm Jan Boonstra; Bas Peeters; Kostas Skenderis
1997-01-01
We consider a series of duality transformations that leads to a constant shift in the harmonic functions appearing in the description of a configuration of branes. This way, for several intersections of branes, we can relate the original brane configuration which is asymptotically flat to a geometry of the type adSk × El × Sm. The implications of our results
NSDL National Science Digital Library
Terese Herrera
This resource guide from the Middle School Portal 2 project, written specifically for teachers, provides links to exemplary resources including background information, lessons, career information, and related national science education standards. The online resources featured in Geometry in 3-D actively engage students in exploring a variety of geometric shapes, at times through lessons that involve building models or creating paper nets that fold into three-dimensional shapes; at other times, through technology that allows students to rotate and zoom in on figures, noting their attributes and complexity. Other lessons offer problems on surface area and volume, a part of every middle school curriculum. The problems, each with a different twist on the subject, challenge students to reconsider their understanding of how to measure solids. Activities for developing spatial sense, another primary objective in teaching geometry, are also featured. Finally, there are online galleries of geometric solids, included for the rare opportunity they offer to show your students the beauty in mathematics. In Background Information, you will find workshop sessions developed for teachers and other materials that may interest you as a professional. Each resource deals specifically with three-dimensional geometry topics that align with the geometry and measurement standards recommended by NCTM.
Spacetime and Euclidean Geometry
Dieter Brill; Ted Jacobson
2004-08-04
Using only the principle of relativity and Euclidean geometry we show in this pedagogical article that the square of proper time or length in a two-dimensional spacetime diagram is proportional to the Euclidean area of the corresponding causal domain. We use this relation to derive the Minkowski line element by two geometric proofs of the "spacetime Pythagoras theorem".
Spacetime and Euclidean geometry
NASA Astrophysics Data System (ADS)
Brill, Dieter; Jacobson, Ted
2006-04-01
Using only the principle of relativity and Euclidean geometry we show in this pedagogical article that the square of proper time or length in a two-dimensional spacetime diagram is proportional to the Euclidean area of the corresponding causal domain. We use this relation to derive the Minkowski line element by two geometric proofs of the spacetime Pythagoras theorem.
Ren, Shiwei; Ma, Xiaochuan; Yan, Shefeng; Hao, Chengpeng
2013-01-01
A unitary transformation-based algorithm is proposed for two-dimensional (2-D) direction-of-arrival (DOA) estimation of coherent signals. The problem is solved by reorganizing the covariance matrix into a block Hankel one for decorrelation first and then reconstructing a new matrix to facilitate the unitary transformation. By multiplying unitary matrices, eigenvalue decomposition and singular value decomposition are both transformed into real-valued, so that the computational complexity can be reduced significantly. In addition, a fast and computationally attractive realization of the 2-D unitary transformation is given by making a Kronecker product of the 1-D matrices. Compared with the existing 2-D algorithms, our scheme is more efficient in computation and less restrictive on the array geometry. The processing of the received data matrix before unitary transformation combines the estimation of signal parameters via rotational invariance techniques (ESPRIT)-Like method and the forward-backward averaging, which can decorrelate the impinging signals more thoroughly. Simulation results and computational order analysis are presented to verify the validity and effectiveness of the proposed algorithm. PMID:23539031
Koh, Kwi Hye; Pan, Xian; Zhang, Wei; McLachlan, Alan; Urrutia, Raul; Jeong, Hyunyoung
2014-12-01
Cytochrome P450 2D6 (CYP2D6), a major drug-metabolizing enzyme, is responsible for metabolism of approximately 25% of marketed drugs. Clinical evidence indicates that metabolism of CYP2D6 substrates is increased during pregnancy, but the underlying mechanisms remain unclear. To identify transcription factors potentially responsible for CYP2D6 induction during pregnancy, a panel of genes differentially expressed in the livers of pregnant versus nonpregnant CYP2D6-humanized (tg-CYP2D6) mice was compiled via microarray experiments followed by real-time quantitative reverse-transcription polymerase chain reaction(qRT-PCR) verification. As a result, seven transcription factors-activating transcription factor 5 (ATF5), early growth response 1 (EGR1), forkhead box protein A3 (FOXA3), JUNB, Krüppel-like factor 9 (KLF9), KLF10, and REV-ERB?-were found to be up-regulated in liver during pregnancy. Results from transient transfection and promoter reporter gene assays indicate that KLF9 itself is a weak transactivator of CYP2D6 promoter but significantly enhances CYP2D6 promoter transactivation by hepatocyte nuclear factor 4 (HNF4?), a known transcriptional activator of CYP2D6 expression. The results from deletion and mutation analysis of CYP2D6 promoter activity identified a KLF9 putative binding motif at -22/-14 region to be critical in the potentiation of HNF4?-induced transactivation of CYP2D6. Electrophoretic mobility shift assays revealed a direct binding of KLF9 to the putative KLF binding motif. Results from chromatin immunoprecipitation assay showed increased recruitment of KLF9 to CYP2D6 promoter in the livers of tg-CYP2D6 mice during pregnancy. Taken together, our data suggest that increased KLF9 expression is in part responsible for CYP2D6 induction during pregnancy via the potentiation of HNF4? transactivation of CYP2D6. PMID:25217496
2-D Finite-Element Models Of Tactile Sensors
S. L. Ricker; R. E. Ellis
1993-01-01
It is proposed that tactile sensors be modeled mechanically with finite-element methods, which capture the geometry and boundary conditions more faithfully than classical techniques. The main advantage of finite-element methods is increased realism of the models. The main disadvantage is a loss of simplicity, especially with respect to providing a model for fast and reliable inversion of the transduced strains
Migrating from 2D to 3D in "Autograph"
ERIC Educational Resources Information Center
Butler, Douglas
2006-01-01
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…
2D imaging by X-ray fluorescence microtomography
NASA Astrophysics Data System (ADS)
Simionovici, A.; Chukalina, M.; Drakopoulos, M.; Snigireva, I.; Snigirev, A.; Schroer, Ch.; Lengeler, B.; Janssens, K.; Adams, F.
2000-05-01
First experimental results of fluorescence microtomography in "pencil-beam" geometry with 6 ?m resolution obtained at the ESRF/1D 22 are described. Image reconstructions are based on either a simplified algebraic reconstruction method (ART) or the filtered back-projection method (FBT). Simple cylindrical test objects are accurately reconstructed.
Normalized 3D to 2D model-based facial image synthesis for 2D model-based face recognition
A-Nasser Ansari; Mohammad H. Mahoor; Mohamed Abdel-Mottaleb
2011-01-01
In our previous research [1-3], we created a database of 3D textured face models of people using stereo images and a generic face mesh model for 3D face recognition application. Consequently, in this paper we make use of this available database and propose an algorithm for synthesizing multiple view 2D facial images of each subject, which extends the number of
Robust mean traveltime curves: a powerful tool for analysis in 2D transmission tomographic surveys
NASA Astrophysics Data System (ADS)
Fernandez Martinez, J.; Pedruelo Gonzalez, L.; Rector, J.
2008-12-01
Acoustic tomography methods belong to the class of non destructive inspection techniques and are widely used in engineering applications. One of the main issues for these methods is the direct arrivals, which can be noisy or affected by scattering or other propagation effects. Mean traveltime curves (mean and standard deviation) have been introduced by Fernández Martínez et al (2006), and describe the variation of the main statistical parameters of the traveltime distribution for the different gathering subsets as a function of the gather index. These curves constitute a simple methodology (Fernández Martínez et al., 2008) to analyze before inversion the traveltime quality in 2D acoustic transmission tomography experiments conducted in relatively homogeneous blocks. This analysis can help to discriminate the contribution of picking errors from that of geological heterogeneities. In this contribution we present the so-called robust mean traveltime curves, which refer to the variation of the different p-percentiles and related measures of dispersion (inter-quartile range and minimum absolute deviation) for the above mentioned gathering subsets. Together with the mean curve, the median and upper-quartile traveltime curves are very resistant to the presence of outliers, and thus, are preferred to infer a background velocity model, which is valid at experiment scale and honors the experimental traveltime distribution. This methodology is valid for 2D zonal isotropic or elliptical anisotropic media, explored via any arbitrary acquisition geometry. We show the application to a well-known granitic medium (Febex Project, Nagra, Switzerland). Fernández Martínez et al. 2006. Mathematical Geology:38-3.343-374 Fernández Martínez et al.2008. Computer and Geosciences:34-3,213-225, 2008.
Room- and low-temperature magnetic properties of 2-D magnetite particle arrays
NASA Astrophysics Data System (ADS)
Krása, David; Muxworthy, Adrian R.; Williams, Wyn
2011-04-01
Palaeomagnetic observations are being used in increasingly sophisticated geological and geophysical interpretations. It is therefore important to test the theories behind palaeomagnetic recording by rocks, and this can only be achieved using samples containing precisely controlled magnetic mineralogy, grain size and interparticle spacing, the last of which controls the degree of magnetostatic interactions within the samples. Here we report the room- and low temperature magnetic behaviour of a set of samples produced by the nano-scale patterning technique electron beam lithography. The samples consist of 2-D arrays of near-identical magnetite dots of various sizes, geometries and spatial configurations, with dot sizes from ranging from near the single domain threshold of 74-333 nm. We have made a series of magnetic measurements including hysteresis, first-order-reversal curve measurements and remanence acquisition, many as a function of temperature between 20 and 300 K, to quantify the samples’ behaviour to routine palaeomagnetic measurement procedures. We have also examined the behaviour of saturation isothermal remanences (SIRM) to cooling and warming cycling of the sample below room temperature. In addition, we investigated the samples’ responses to alternating-field demagnetization of room temperature induced SIRM, anhysteretic remanent magnetization (ARM) and partial ARM. ARM was used as a non-heating analogue for natural thermoremanence. Given the 2-D spatial distribution of the samples, in all the experiments we conducted both in-plane and out-of-plane measurements. Generally, the samples were found to display pseudo-single-domain hysteresis characteristics, but were found to be reliable recorders of weak-field remanences like ARM. For the closely packed samples, the samples’ magnetic response was highly dependent on measurement orientation.
Widom, Julia R.; Johnson, Neil P.; von Hippel, Peter H.; Marcus, Andrew H.
2013-01-01
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 Ĺ ± 0.5 Ĺ, twist angle ?12 = 5° ± 5°), which differs from the conformation of such adjacent bases in duplex DNA. These experiments establish UV-2D FS as a method for examining the local conformations of an adjacent pair of fluorescent nucleotides substituted into specific DNA or RNA constructs, which will serve as a powerful probe to interpret, in structural terms, biologically significant local conformational changes within the nucleic acid framework of protein-nucleic acid complexes. PMID:24223491
Crews, K R; Gaedigk, A; Dunnenberger, H M; Klein, T E; Shen, D D; Callaghan, J T; Kharasch, E D; Skaar, T C
2012-02-01
Codeine is bioactivated to morphine, a strong opioid agonist, by the hepatic cytochrome P450 2D6 (CYP2D6); hence, the efficacy and safety of codeine as an analgesic are governed by CYP2D6 polymorphisms. Codeine has little therapeutic effect in patients who are CYP2D6 poor metabolizers, whereas the risk of morphine toxicity is higher in ultrarapid metabolizers. The purpose of this guideline (periodically updated at http://www.pharmgkb.org) is to provide information relating to the interpretation of CYP2D6 genotype test results to guide the dosing of codeine. PMID:22205192
Sebastian Schunert; Yousry Y. Azmy; Damien Fournier
2011-05-01
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.
NASA Astrophysics Data System (ADS)
Caputo, Jean-Guy; Flytzanis, Nikos; Gaididei, Yuri; Moulitsa, Irene; Vavalis, Emmanuel
We introduce a new type of splitting method for semilinear partial differential equations. The method is analyzed in detail for the case of the two-dimensional static sine-Gordon equation describing a large area Josephson junction with overlap current feed and external magnetic field. The solution is separated into an explicit term that satisfies the one-dimensional sine-Gordon equation in the y-direction with boundary conditions determined by the bias current and a residual which is expanded using modes in the y-direction, the coefficients of which satisfy ordinary differential equations in x with boundary conditions given by the magnetic field. We show by direct comparison with a two-dimensional solution that this method converges and that it is an efficient way of solving the problem. The convergence of the y expansion for the residual is compared for Fourier cosine modes and the normal modes associated to the static one-dimensional sine-Gordon equation and we find a faster convergence for the latter. Even for such large widths as w=10 two such modes are enough to give accurate results.
Investigation of the Effect of Deformable Trailing Edge Geometry Control Systems on Flutter Velocity
Investigation of the Effect of Deformable Trailing Edge Geometry Control Systems on Flutter control system on flutter velocity in the 2D case. The focus of this work is on the difference in flutter control system parameters, including both PD control parameters as well as control system timelag
Integrating Automated Range Registration with Multiview Geometry for the Photorealistic Modeling
Stamos, Ioannis
photography. This paper presents a system that integrates automated 3D-to-3D and 2D-to-3D registra- tion techniques, with multiview geometry for the photorealistic modeling of urban scenes. The 3D range scans are registered using our automated 3D-to-3D registra- tion method that matches 3D features (linear or circular
Optimization of multistatic passive radar geometry based on CRLB with uncertain observations
V. Anastasio; F. Colone; A. Di Lallo; A. Farina; F. Gumiero; P. Lombardo
2010-01-01
In the present paper, we derive the Cramer-Rao Lower Bound (CRLB) with uncertain observations, namely for Pd<;1, for the 2D position measurements of a multistatic passive radar, to optimize the geometry of the system. This is an extension of the enumeration method CRLB to the multisensor case, where it is considered that the multiple receivers could detect or miss the
Using real data for the implementation of multistatic passive radar geometry optimization procedure
F. Gumiero; S. Santarelli; C. Bongioanni; F. Colone; P. Lombardo
2011-01-01
This paper presents the results of the application to specific real air traffic scenarios of a design procedure developed in [1]–[2], that aims at passive radar system performance optimization in terms of 2D positioning accuracy. Specifically the presented procedure guides the designer to select the multistatic radar geometry configuration that maximizes the twodimensional target positioning accuracy. A preliminary statistical study
Abstract. Geometry and Complex Numbers GEOMETRY AND COMPLEX NUMBERS
Lee, Carl
Abstract. Geometry and Complex Numbers GEOMETRY AND COMPLEX NUMBERS JERZY DYDAK Contents 1. Introduction 2 2. Solving equations 10 3. Geometric proofs 20 Key words and phrases. Complex numbers. 1 #12-Euclidean, Projective, and Discrete' by Michael Henle (2nd edition, Prentice Hall). (2) `Complex numbers and geometry
2D reflection seismic investigations in the Kevitsa Ni-Cu-PGE deposit, northern Finland
NASA Astrophysics Data System (ADS)
Koivisto, E.; Malehmir, A.; Heikkinen, P.; Heinonen, S.; Kukkonen, I.
2012-04-01
In 2007, 2D reflection seismic survey was conducted in the Kevitsa Ni-Cu-PGE (platinum group elements) deposit, northern Finland as a part of the HIRE (High Resolution Reflection Seismics for Ore Exploration 2007-2010) project of the Geological Survey of Finland. The Kevitsa 2D seismic survey consists of four connected survey lines, each approximately 6-8 km long. The survey lines traverse the ore-bearing Kevitsa intrusive complex and partly also the geological units surrounding it, thus providing an insight to the structural make-up of the complex. The aim of the survey was to delineate the overall shape and basal contact of the Kevitsa ultramafic intrusive complex at depth, to study the seismic response of the disseminated Kevitsa Ni-Cu-PGE deposit, and to potentially find indications for new ore deposits. Herein, we present results from processing and interpretation of the Kevitsa 2D reflection seismic data. In the data processing sequence, specific focus was given to finding optimal CDP-line geometries for the crooked-line survey profiles, and to detailed velocity analysis. We also conducted a simplified cross-dip analysis to assess the potential cross-profile dips of the reflectors, however, application of the cross-dip corrections was found to be unnecessary, and our conventional processing sequence involving prestack DMO corrections followed by poststack migration resulted in high-quality images of the subsurface. The seismic sections presented in this work reveal a detailed reflectivity structure of the uppermost 5 kilometers. The known Kevitsa deposit was found to have a specific seismic signature, and the seismic images were used to establish previously unknown shape and extent of the ore-bearing Kevitsa intrusive complex, thus providing a framework for effective future exploration in the area. Interestingly, the data reveal complex internal reflectivity structure within the intrusion, suggesting multiple levels of intrusion within the pre-existing stratigraphy, and a deeper continuation of the intrusion. A complicated pattern of faults brackets the known deposit, and a series of major fault and shear zones brackets the Kevitsa intrusive complex as a whole. The major structures identified in the seismic sections may potentially be related to the origin of Kevitsa. The data also indicate a possible relationship between the Kevitsa intrusive complex and the nearby Satovaara complex, however, the exact relationship of this complex to the Kevitsa intrusive complex needs to be established through future drilling. Acknowledgements: Kevitsa Mining Oy/First Quantum Minerals Ltd
NASA Astrophysics Data System (ADS)
Vinsard, G.; Dufour, S.; Saatdjian, E.; Mota, J. P. B.
2015-04-01
Chaotic advection can effectively enhance the heat transfer rate between a boundary and fluids with high Prandtl number. These fluids are usually highly viscous and thus turbulent agitation is not a viable solution since the energy required to mix the fluid would be prohibitive. Here, we analyze previously obtained results on chaotic advection and heat transfer in two similar 2-D periodic flows and on their corresponding 3-D periodic flows when an axial velocity component is superposed. The two flows studied are the flow between eccentric rotating cylinders and the flow between confocal ellipses. For both of these flows the analysis is simplified because the Stokes equations can be solved analytically to obtain a closed form solution. For both 2-D periodic flows, we show that chaotic heat transfer is enhanced by the displacement of the saddle point location during one period. Furthermore, the enhancement by chaotic advection in the elliptical geometry is approximately double that obtained in the cylindrical geometry because there are two saddle points instead of one. We also explain why, for high eccentricity ratios, there is no heat transfer enhancement in the cylindrical geometry. When an axial velocity component is added to both of these flows so that they become 3-D, previous work has shown that there is an optimum modulation frequency for which chaotic advection and heat transfer enhancement is a maximum. Here we show that the optimum modulation frequency can be derived from results without an axial flow. We also explain by physical arguments other previously unanswered questions in the published data.
Kim, Sung-Kon; Wie, Jeong Jae; Mahmood, Qasim; Park, Ho Seok
2014-07-01
Polymer inorganic nanosheet composites hold great promise in enhancing their physical and mechanical properties by increasing the interfacial area. Herein, we demonstrate the nanoinclusion effects of two-dimensional (2D) molybdenum disulfide (MoS2) and tungsten disulfide (WS2) nanosheets on the mechanical properties of the poly(vinyl alcohol) (PVA) polymer. At very small amounts of nanosheets (0.9 wt% for MoS2 and 2.0 wt% for WS2), nanocomposite films exhibit up to 65% improved mechanical properties than the neat PVA film because of strong non-covalent polymer-filler interactions by means of large contact area induced by the 2D geometry of nanosheets. As demonstrated by the decrease in the crystallinity of PVA and the increase in the glass transition temperature, 2D MoS2 is a more attractive filler than 2D WS2 in terms of reinforcing mechanical properties of PVA. These findings fit well with a modified Halpin-Tsai (H-T) model including a nanoscale interfacial layer that can support the observed reinforcements with extremely small 2D filler loadings. This study highlights the strong interplay between the polymer and inorganic nanosheets which plays an important role in greatly improving the mechanical stability of nanocomposites. PMID:24879420
2D to 3D conversion implemented in different hardware
NASA Astrophysics Data System (ADS)
Ramos-Diaz, Eduardo; Gonzalez-Huitron, Victor; Ponomaryov, Volodymyr I.; Hernandez-Fragoso, Araceli
2015-02-01
Conversion of available 2D data for release in 3D content is a hot topic for providers and for success of the 3D applications, in general. It naturally completely relies on virtual view synthesis of a second view given by original 2D video. Disparity map (DM) estimation is a central task in 3D generation but still follows a very difficult problem for rendering novel images precisely. There exist different approaches in DM reconstruction, among them manually and semiautomatic methods that can produce high quality DMs but they demonstrate hard time consuming and are computationally expensive. In this paper, several hardware implementations of designed frameworks for an automatic 3D color video generation based on 2D real video sequence are proposed. The novel framework includes simultaneous processing of stereo pairs using the following blocks: CIE L*a*b* color space conversions, stereo matching via pyramidal scheme, color segmentation by k-means on an a*b* color plane, and adaptive post-filtering, DM estimation using stereo matching between left and right images (or neighboring frames in a video), adaptive post-filtering, and finally, the anaglyph 3D scene generation. Novel technique has been implemented on DSP TMS320DM648, Matlab's Simulink module over a PC with Windows 7, and using graphic card (NVIDIA Quadro K2000) demonstrating that the proposed approach can be applied in real-time processing mode. The time values needed, mean Similarity Structural Index Measure (SSIM) and Bad Matching Pixels (B) values for different hardware implementations (GPU, Single CPU, and DSP) are exposed in this paper.
Human erythrocytes analyzed by generalized 2D Raman correlation spectroscopy
NASA Astrophysics Data System (ADS)
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
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.
Geometry for the Secondary School
ERIC Educational Resources Information Center
Moalem, D.
1977-01-01
A sequential but non-axiomatic high school geometry course which includes Euclidean, transformation, and analytic geometry and vectors and matrices, and emphasizes the invariance property of transformations, is outlined. Sample problems, solutions, and comments are included. (MN)
NASA Astrophysics Data System (ADS)
Smania, Daniel
2007-07-01
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.
Nebeck, H.E.
1986-08-01
The MAZE mesh generator represents an arbitrary two dimensional region of space as an ordered collection of quadrilateral elements. Each element is defined by its four corner points (nodes) and an integer material number. Models are created by subdividing the region(s) of interest into one or more PARTS and specifying the element distribution in each part. Then, parts can be merged together to form the meshed representation of the entire region. Applying boundary conditions and describing material properties completes the model construction process. This activity takes place in three distinct phases: phase I-define geometry, subdivide regions into elements; phase II-refine geometry, establish interface and boundary conditions; phase III-describe material properties. This work presents explanations and examples of the phase I commands, along with an overview of the MAZE mesh generation process.
Synthesis, Characterization, Properties, and Tribological Performance of 2D Nanomaterials
He, Xingliang
2014-04-25
of the inorganic film-forming additive. 1.1.3. Anti-wear and extreme-pressure additives Under the conditions of high load, low speed, or little viscosity, high asperities on the mating surfaces interact with each other. This occurs initially through.... ..................................................................................... 99 Figure 5.22. 2D nanostructured B2O3-induced surface improvement during CMP (left); layered nanostructure of B2O3 (right) ............................................. 100 xvi Figure 5.23. Surface roughness on Cu films before and after CMP...
Faceting and branching in 2D crystal growth.
Tegze, György; Tóth, Gyula I; Gránásy, László
2011-05-13
Using atomic scale time-dependent density functional calculations we confirm that both diffusion-controlled and diffusionless crystallization modes exist in simple 2D systems. We provide theoretical evidence that a faceted to nonfaceted transition is coupled to these crystallization modes, and faceting is governed by the local supersaturation at the fluid-crystalline interface. We also show that competing modes of crystallization have a major influence on mesopattern formation. Irregularly branched and porous structures are emerging at the crossover of the crystallization modes. The proposed branching mechanism differs essentially from dendritic fingering driven by diffusive instability. PMID:21668173
Spontaneous synchronized bursting in 2D neural networks
NASA Astrophysics Data System (ADS)
Segev, Ronen; Ben-Jacob, Eshel
2001-12-01
We present a long-term (hours) measurements of the spontaneous activity of cortical cells 2D neural network placed on multi-electrodes arrays. We compare the histogram of the single neurons inter spike interval and the network inter synchronized bursting events interval. In addition, the effect of Ca concentration on the network activity is being studied. Under 1 mM Ca concentration the network exhibits periodic synchronized bursting. We present a novel feedback regulated integrate & fire model to account of the observations. In the model we include two additional features of dynamical threshold and synapses fatigue.
Melting of 2D Coulomb clusters in dusty plasmas
Ichiki, R; Wolter, M; Kawai, Y; Melzer, A; Ichiki, Ryuta; Ivanov, Yuriy; Wolter, Matthias; Kawai, Yoshinobu; Melzer, Andre
2004-01-01
The melting of 2D dust clusters caused by one additional particle in the lower layer has experimentally been observed to undergo a two-step transition, which divides the phase of the cluster into three stages. The first transition is a jump of the dust kinetic energy due to the onset of an instability of the lower-layer particle, shifting the cluster from an ordinary to a hot crystalline state. The second transition is the actual phase transition into a liquid state, which occurs at a decisively lower gas pressure. The detailed dynamical properties of the system during the transition were determined in terms of the normal mode analysis.
2D Neutron Diffraction Imaging on an Ammonite
NASA Astrophysics Data System (ADS)
Shamoto, Shin-ichi; Kodama, Katsuaki; Imaki, Tadashi; Nakatani, Takeshi; Oshita, Hidetoshi; Kaneko, Naokatsu; Masuko, Kenji; Sakamoto, Kensaku; Yamaguchi, Kenji; Suzuya, Kentaro; Otomo, Toshiya
2D neutron diffraction imaging of an ammonite fossil was carried out at high-intensity total diffractometer NOVA in J-PARC. Observed diffraction profiles consist of calcite, siderite and amorphous structures. Most of part in the ammonite is calcite. The calcite image shows air chambers divided by septa in the spiral shell. Siderite is observed only in the body chamber. Amorphous structure is observed in both the protoconch and the inner whorls. Based on the crystal structures, their chemical compositions are discussed.
Transport Experiments on 2D Correlated Electron Physics in Semiconductors
Tsui, Daniel
2014-03-24
This research project was designed to investigate experimentally the transport properties of the 2D electrons in Si and GaAs, two prototype semiconductors, in several new physical regimes that were previously inaccessible to experiments. The research focused on the strongly correlated electron physics in the dilute density limit, where the electron potential energy to kinetic energy ratio rs>>1, and on the fractional quantum Hall effect related physics in nuclear demagnetization refrigerator temperature range on samples with new levels of purity and controlled random disorder.
Exact solutions for the 2d one component plasma
Timothy D. Andersen
2013-02-13
The 2d one component gas of pointlike charges in a uniform neutralizing background interacting with a logarithmic potential is a common model for plasmas. In its classical equilibrium statistics at fixed temperature (canonical ensemble) it is formally related to certain types of random matrices with Gaussian distribution and complex eigenvalues. In this paper, I present an exact integration of this ensemble for $N$ such particles (or alternatively $N\\times N$ matrices) for all even non-negative temperatures, a significant open problem in statistical physics for several decades. I achieve this exact integration via an exact integration of a related ensemble, the two-dimensional Selberg integral.
PARCEQ2D heat transfer grid sensitivity analysis
NASA Technical Reports Server (NTRS)
Saladino, Anthony J.; Praharaj, Sarat C.; Collins, Frank G.
1991-01-01
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.
Black liquor gasification phase 2D final report
Kohl, A.L.; Stewart, A.E.
1988-06-01
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.
2D spectroscopy of double-barred galaxies
A. V. Moiseev; J. R. Valdes; V. H. Chavushyan
2002-02-13
The first results of the observational program of the study of 2D-kinematics in double-barred galaxies are presented. We show that, for the main part of the sample, the inner bars do not affect the circumnuclear stellar kinematics. Therefore, they are not dynamically decoupled structures. Various types of non-circular gas motion were found in many galaxies. The analysis of the ground-based and HST optical and NIR images reveals mini-spirals in about half of the investigated objects. We suggest that so called ``double-barred galaxies'' are, in fact, galaxies with very different circumnuclear structure.
2D vector map watermarking based on spatial relations
NASA Astrophysics Data System (ADS)
Wu, Baiyan; Wang, Wei; Miao, Dandan
2008-12-01
We describe a method, based on spatial relations, to generate algorithms for watermarking 2D vector map. The method consists of: defining and computing the metric meatures of topological relations between map objects; extracting cover data from metric meatures; deviding the cover data into different subsets; adjusting the spatial relations between map objects within the precision tolerance of the map to make the cover data distribution of one subset shows one of the two expected patterns to suggest the embedding of bit 1 or 0. The method is blind and experiments show that it is also robust.
Optical Tweezers Array System Based on 2D Photonic Crystals
NASA Astrophysics Data System (ADS)
Ren, Xuechang; Wang, Canhui; Li, Yanshuang; Shen, Shaoxin; Liu, Shou
A simple optical interference method for creating multiple optical tweezers from a single laser beam, using two dimentional photonic crystals (PhCs) as a diffractive beam splitter, was described. To obtained clear periodic traps, all diffracted beams sould be used and the intensity of each splitted beam should be same. So the period and the surface features of PhCs was adjusted in the present study As a demonstration of this technique, using 2D PhCs with 700 nanometer period, hexagonal lattice patterns with one micrometer period have been implemented. The image of periodic intensity gradient of light fabricated by this method is presented.
2D Magneto-Optical Trapping of Diatomic Molecules
NASA Astrophysics Data System (ADS)
Hummon, Matthew T.; Yeo, Mark; Stuhl, Benjamin K.; Collopy, Alejandra L.; Xia, Yong; Ye, Jun
2013-04-01
We demonstrate one- and two-dimensional transverse laser cooling and magneto-optical trapping of the polar molecule yttrium (II) oxide (YO). In a 1D magneto-optical trap (MOT), we characterize the magneto-optical trapping force and decrease the transverse temperature by an order of magnitude, from 25 to 2 mK, limited by interaction time. In a 2D MOT, we enhance the intensity of the YO beam and reduce the transverse temperature in both transverse directions. The approach demonstrated here can be applied to many molecular species and can also be extended to 3D.
SU-D-12A-04: Investigation of a 2D Antiscatter Grid for Flat Panel Detectors
Altunbas, C; Kavanagh, B; Miften, M [University of Colorado School of Medicine, Aurora, CO (United States); Zhong, Y; Shaw, C [UT MD Anderson Cancer Center, Houston, TX (United States)
2014-06-01
Purpose: To improve CT number accuracy and contrast sensitivity, a novel 2D antiscatter grid (ASG) for flat panel detector (FPD) based CBCT imaging was evaluated. Experiments were performed to characterize the scatter rejection and contrast sensitivity performance of ASG. The reduction in primary transmission for various ASG geometries was also evaluated by a computational model. Methods: The 2D ASG design was based on multi-hole collimators used in Nuclear Medicine. It consisted of abutted hexagon shaped apertures with 2.5 mm pitch and 32 mm height, and separated by 0.25 mm thick lead septa. Scatter-to-primary ratio (SPR), contrast-to-noise ratio (CNR), and mean primary transmission were measured using a benchtop FPD/x-ray source system. Acrylic slabs of varying thicknesses were imaged with a contrast-detail phantom to measure CNR and SPR under different scatter conditions. Primary transmission was also measured by averaging pixel values in flood field images without the phantom. We additionally explored variation of primary transmission with pitch and septum thickness using a computational model of our ASG. Results: Our 2D ASG reduced the SPR from 3.3 to 0.12, and improved CNR by 50% in 20 cm thick slab phantom projections acquired at 120 kVp. While the measured primary transmission was 72.8%, our simulations show that primary transmission can be increased to 86% by reducing the septum thickness to 0.1 mm. Primary transmission further increases to 93% if septum thickness of 0.1 mm is used in conjunction with an increased pitch of 4 mm. Conclusion: The 2D ASG appears to be a promising scatter rejection device, offering both superior scatter rejection and improved contrast sensitivity. Though its lead footprint reduced primary transmission, our work shows that optimization of aperture pitch and septum thickness can significantly improve the primary transmission.
NON COMMUTATIVE DIFFERENTIAL GEOMETRY
Michel Dubois-Violette; Peter W. Michor
In commutative differential geometry the Frolicher-Nijenhuis bracket computes all kinds of curvatures and obstructions to integrability. In (1) the Frolicher- Nijenhuis bracket was developed for universal differential forms of non-commutative algebras, and several applications were given. In this paper this bracket and the Frolicher-Nijenhuis calculus will be developed for several kinds of differential graded algebras based on derivations, which were
Freezing in confined geometries
NASA Technical Reports Server (NTRS)
Sokol, P. E.; Ma, W. J.; Herwig, K. W.; Snow, W. M.; Wang, Y.; Koplik, Joel; Banavar, Jayanth R.
1992-01-01
Results of detailed structural studies, using elastic neutron scattering, of the freezing of liquid O2 and D2 in porous vycor glass, are presented. The experimental studies have been complemented by computer simulations of the dynamics of freezing of a Lennard-Jones liquid in narrow channels bounded by molecular walls. Results point to a new simple physical interpretation of freezing in confined geometries.
Electroencephalography in ellipsoidal geometry
Fotini Kariotou
2004-01-01
The human brain is shaped in the form of an ellipsoid with average semiaxes equal to 6, 6.5 and 9 cm. This is a genuine 3-D shape that reflects the anisotropic characteristics of the brain as a conductive body. The direct electroencephalography problem in such anisotropic geometry is studied in the present work. The results, which are obtained through successively solving an
Integral Geometry and Holography
Bartlomiej Czech; Lampros Lamprou; Samuel McCandlish; James Sully
2015-05-20
We present a mathematical framework which underlies the connection between information theory and the bulk spacetime in the AdS$_3$/CFT$_2$ correspondence. A key concept is kinematic space: an auxiliary Lorentzian geometry whose metric is defined in terms of conditional mutual informations and which organizes the entanglement pattern of a CFT state. When the field theory has a holographic dual obeying the Ryu-Takayanagi proposal, kinematic space has a direct geometric meaning: it is the space of bulk geodesics studied in integral geometry. Lengths of bulk curves are computed by kinematic volumes, giving a precise entropic interpretation of the length of any bulk curve. We explain how basic geometric concepts -- points, distances and angles -- are reflected in kinematic space, allowing one to reconstruct a large class of spatial bulk geometries from boundary entanglement entropies. In this way, kinematic space translates between information theoretic and geometric descriptions of a CFT state. As an example, we discuss in detail the static slice of AdS$_3$ whose kinematic space is two-dimensional de Sitter space.
Implicit Computation Geometry Henrik Blunck
Brodal, Gerth Střlting
Implicit Computation Geometry Henrik Blunck Department of Computer Science WWU M¨unster #12 Implicit Computation Geometry 1 #12;Motivation Traditional focus in algorithm design: Running Time Here/write)-memory Sensor Networks Car Navigation Henrik Blunck Implicit Computation Geometry 2 #12;In-Place Algorithms
Noncommutative geometry for arbitrary braidings
NASA Astrophysics Data System (ADS)
Marcinek, Wl/adysl/aw
1994-05-01
The noncommutative geometry corresponding to arbitrary braidings is studied in a purely algebraical way. The new and original proposal of the geometry is given in terms of the theory of braided monoidal categories. The quantum oscillator is considered as an example of application of our geometry.
Geometry for Santiago and Mathias
NSDL National Science Digital Library
Nora
2009-06-05
The Klings can practice their geometry skills through fun games. Test your geometry knowledge in Shape Hangman!! Practice what you know in the sort trianles. Do you reallyGrasp Geometry? Measuring area of rectangles, good for Santi Area of Rectangles BBC Cool Geoboard for Santi Interactive geoboard More area measuring Tutorial with game ...
De mme, pour A == 23r, Z~ .---
Paris-Sud XI, Université de
4~. SPECTRES D'ABSORPTION ET D'ÉMISSION L DU DYSPROSIUM Par GILBERT BARRČRE. Attaché de Recherches discontinuités d'absorption L du dysprosium sont mesurées et étudiées avec les structures qui les accompagnent valeurs suivantes pour les longueurs d'onde des discontinuités du dysprosium : On voit qu'une révision de
Force chains and hysteresis in a 2D granular piston
NASA Astrophysics Data System (ADS)
Hartley, R. R.; Behringer, R. P.; Kolb, E.; Ovarlez, G.; Clement, E.
2001-11-01
We present photoelastic studies of force distributions and propagation in a 2D granular piston.footnote E. Kolb, et. al. Europhys. J. B. 8, 483-491 (1999). The particles, ~ 1/2 cm disks, are confined by rigid sidewalls and pushed against gravity by a piston at constant velocity in the range 10-150 ? m/s. Friction prevents the free rotation and displacement of particles within the bulk of the material and leads to the buildup of stress chains resisting motion. The local and global stress within the granular material can be extracted by placing the experiment between complimentary circular polarizers. We find that the initial preparation (where the particles rain down in bulk) gives a stress minimum in the middle and edges, while the stress is polarized and maximal along each sidewall. The 2D pressure saturates at a depth ~ 1/2 width, and uniform compressive loads show hysteresis within the bulk. Under shear, we present evidence of stick-slip dynamics and large-scale convection when the particles can mobilize after dilation.