Collective motion of squirmers in a quasi-2D geometry
NASA Astrophysics Data System (ADS)
Zöttl, Andreas; Stark, Holger
2013-03-01
Microorganisms like bacteria, algae or spermatozoa typically move in an aqueous environment where they interact via hydrodynamic flow fields. Recent experiments studied the collective motion of dense suspensions of bacteria where swarming and large-scale turbulence emerged. Moreover, spherical artificial microswimmers, so-called squirmers, have been constructed and studied in a quasi-2D geometry. Here we present a numerical study of the collective dynamics of squirmers confined in quasi-2D between two parallel walls. Because of their spherical shape the reorientation of squirmers is solely due to noise and hydrodynamic interactions via induced flow fields. This is in contrast to elongated swimmers like bacteria which locally align due to steric interactions. We study the collective motion of pushers, pullers and potential swimmers at different densities. At small densities the squirmers are oriented parallel to the walls and pairwise collisions determine the reorientation rate. In dense suspensions rotational diffusion is greatly enhanced and pushers, in particular, tend to orient perpendicular to the walls. This effects the dynamics of the emerging clusters. In very dense suspensions we observe active jamming and long-lived crystalline structures.
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.
the distinct roots of q(z) = 0, and suppose that p(ai) = 0, i = 1, .., n. Show that R has a partial fraction decomposition, i.e. R(z) = n i=1 ri(z), where ri is a rational function which vanishes at and whose only
Using Stereo Matching with General Epipolar Geometry for 2D Face Recognition
Daume III, Hal
Using Stereo Matching with General Epipolar Geometry for 2D Face Recognition across Pose Carlos D. Castillo, Student Member, IEEE, and David W. Jacobs, Member, IEEE Abstract--Face recognition across pose this, we show that, for conditions common in face recognition, the epipolar geometry of face images can
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.
Westerly, David C.; Mo Xiaohu; DeLuca, Paul M. Jr.; Tome, Wolfgang A.; Mackie, Thomas R.
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.
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.
Evaluation of 2D shallow-water model for spillway flow with a complex geometry
Technology Transfer Automated Retrieval System (TEKTRAN)
Although the two-dimensional (2D) shallow water model is formulated based on several assumptions such as hydrostatic pressure distribution and vertical velocity is negligible, as a simple alternative to the complex 3D model, it has been used to compute water flows in which these assumptions may be ...
A distributional approach to the geometry of 2D dislocations at the mesoscale
Lisbon, University of
. The fundamental identity relating the incompatibility tensor to the Frank and Burgers vectors is proved in the 2D dislocation segment has a constant Burgers vector which exhibits additive properties at dislocation junctions of these principles and of the pioneer works of Volterra (1907) and Cosserat (1909), Burgers (1939), Eshelby (1956
Maduri, Rajesh Kumar
2008-02-01
approximations in designing finite element computational processes has been demonstrated by Surana and co-workers [1-4]. It has been shown by Surana et al. [5] that when the element geometry is rectangular, higher order global differentiability approximations can...
ORMGEN. PC: a microcomputer program for automatic mesh generation of 2-D crack geometries
Bryson, J.W.; Bass, B.R.
1986-03-01
ORMGEN.PC (Oak Ridge Mesh GENeration.Personal Computer) automatically generates two-dimensional finite-element models for either cracked or uncracked structures. Element connectivities and nodal point coordinates are written in formats that are compatible for subsequent fracture analysis using either the ORVIRT.PC finite-element microcomputer program or the ADINA/ORVIRT mainframe system. ORMGEN.PC emphasizes generality in its design. Finite-element models can be generated for disks, plates, cylinders, and even geometries with holes, such as compact tension specimens. Either surface or embedded flaw geometries can be modeled. Detailed user instructions describe both preparation of input data and program operation. Sample problems are presented that demonstrate the flexibility of the program. ORMGEN.PC executes on an IBM PC/AT or PC/XT microcomputer; typical runtimes on an IBM PC/AT are 30 to 45 s. 20 figs.
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.
2D Geometry Predicts Perceived Visual Curvature in Context-Free Viewing
Dresp-Langley, Birgitta
2015-01-01
Planar geometry was exploited for the computation of symmetric visual curves in the image plane, with consistent variations in local parameters such as sagitta, chordlength, and the curves' height-to-width ratio, an indicator of the visual area covered by the curve, also called aspect ratio. Image representations of single curves (no local image context) were presented to human observers to measure their visual sensation of curvature magnitude elicited by a given curve. Nonlinear regression analysis was performed on both the individual and the average data using two types of model: (1) a power function where y (sensation) tends towards infinity as a function of x (stimulus input), most frequently used to model sensory scaling data for sensory continua, and (2) an “exponential rise to maximum” function, which converges towards an asymptotically stable level of y as a function of x. Both models provide satisfactory fits to subjective curvature magnitude as a function of the height-to-width ratio of single curves. The findings are consistent with an in-built sensitivity of the human visual system to local curve geometry, a potentially essential ground condition for the perception of concave and convex objects in the real world. PMID:26346803
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)
Moustafa, Salli; Févotte, François; Lathuilière, Bruno; Plagne, Laurent
2014-06-01
The past few years have been marked by a noticeable increase in the interest in 3D whole-core heterogeneous deterministic neutron transport solvers for reference calculations. Due to the extremely large problem sizes tackled by such solvers, they need to use adapted numerical methods and need to be efficiently implemented to take advantage of the full computing power of modern systems. As for numerical methods, one possible approach consists in iterating over resolutions of 2D and 1D MOC problems by taking advantage of prismatic geometries. The MICADO solver, developed at EDF R&D, is a parallel implementation of such a method in distributed and shared memory systems. However it is currently unable to use SIMD vectorization to leverage the full computing power of modern CPUs. In this paper, we describe our first effort to support vectorization in MICADO, typically targeting Intel© SSE CPUs. Both the 2D and 1D algorithms are vectorized, allowing for high expected speedups for the whole spatial solver. We present benchmark computations, which show nearly optimal speedups for our vectorized implementation on the TAKEDA case.
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.
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.
NASA Astrophysics Data System (ADS)
Chaudhuri, A.; Sekhar, M.; Descloitres, M.; Godderis, Y.; Ruiz, L.; Braun, J. J.
2013-11-01
Stochastic modelling is a useful way of simulating complex hard-rock aquifers as hydrological properties (permeability, porosity etc.) can be described using random variables with known statistics. However, very few studies have assessed the influence of topological uncertainty (i.e. the variability of thickness of conductive zones in the aquifer), probably because it is not easy to retrieve accurate statistics of the aquifer geometry, especially in hard rock context. In this paper, we assessed the potential of using geophysical surveys to describe the geometry of a hard rock-aquifer in a stochastic modelling framework. The study site was a small experimental watershed in South India, where the aquifer consisted of a clayey to loamy-sandy zone (regolith) underlain by a conductive fissured rock layer (protolith) and the unweathered gneiss (bedrock) at the bottom. The spatial variability of the thickness of the regolith and fissured layers was estimated by electrical resistivity tomography (ERT) profiles, which were performed along a few cross sections in the watershed. For stochastic analysis using Monte Carlo simulation, the generated random layer thickness was made conditional to the available data from the geophysics. In order to simulate steady state flow in the irregular domain with variable geometry, we used an isoparametric finite element method to discretize the flow equation over an unstructured grid with irregular hexahedral elements. The results indicated that the spatial variability of the layer thickness had a significant effect on reducing the simulated effective steady seepage flux and that using the conditional simulations reduced the uncertainty of the simulated seepage flux. As a conclusion, combining information on the aquifer geometry obtained from geophysical surveys with stochastic modelling is a promising methodology to improve the simulation of groundwater flow in complex hard-rock aquifers.
Bailey, T S; Adams, M L; Chang, J H
2008-10-01
We present a new spatial discretization of the discrete-ordinates transport equation in two-dimensional cylindrical (RZ) geometry for arbitrary polygonal meshes. This discretization is a discontinuous finite element method that utilizes the piecewise linear basis functions developed by Stone and Adams. We describe an asymptotic analysis that shows this method to be accurate for many problems in the thick diffusion limit on arbitrary polygons, allowing this method to be applied to radiative transfer problems with these types of meshes. We also present numerical results for multiple problems on quadrilateral grids and compare these results to the well-known bi-linear discontinuous finite element method.
NASA Astrophysics Data System (ADS)
Schmiedel, T.; Breitkreuz, C.; Görz, I.; Ehling, B.-C.
2015-03-01
Well data and core samples from the Late Paleozoic Halle Volcanic Complex (HVC) have been used to describe the geometry of the rhyolitic porphyritic laccoliths and their margins. The HVC formed between 301 and 292 Ma in the intramontane Saale basin, and it comprises mainly rhyolitic subvolcanic bodies (~300 km3) as well as minor lava flows and volcaniclastic deposits. The major HVC laccolith units display aspect ratios ranging between 0.04 and 0.07, and they are separated by tilted and deformed Carboniferous-Permian host sediments. For the margin of the Landsberg laccolith, a major coarsely porphyritic unit of the HVC, an exceptional data set of 63 wells concentrated in an area of 10 km2 reaching to depth of 710 m exists. It was used to explore the 3D geometry and textures, and to deduce an intrusion model. For a 3D visualization of the Landsberg laccolith margin, Geological Object Computer Aided Design; Paradigm® software (GOCAD) was used. Curve objects have been derived from the intrusion-host contacts. Automated GOCAD® methods for 3D modelling failed. As a result, manual refinement was essential. A major finding of the 3D modelling is the presence of prolate sediment rafts, up to 1,400 m in length and up to 500 m in thickness, surrounded by Landsberg rhyolite. The sedimentary rafts dip away from the laccolith centre. The engulfing laccolith sheets reach thickness of 100-300 m. For other HVC laccolith units (Löbejün, Petersberg, Brachstedt), well data reveal vertical rhyolite/sediment contacts or magma lobes fingering into the host sediments. HVC laccolith contact textures include small-scale shearing of the intruding magma and of the host sediment. In addition, internal shear zones have been detected inside the rhyolite bodies. The present study suggests that the emplacement of successive magma sheets was an important process during laccolith growth in the HVC.
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
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)
Centeno, Felipe Roman; Brittes, Rogério; França, Francis. H. R.; Ezekoye, Ofodike A.
2015-05-01
The weighted-sum-of-gray-gases (WSGG) model is widely used in engineering computations of radiative heat transfer due to its relative simplicity, robustness and flexibility. This paper presents the computation of radiative heat transfer in a 2D axisymmetric chamber using two WSGG models to compute radiation in H2O and CO2 mixtures. The first model considers a fixed ratio between the molar concentrations of H2O and CO2, while the second allows the solution for arbitrary ratios. The correlations for both models are based on the HITEMP2010 database. The test case considers typical conditions found in turbulent methane flames, with steep variations in the temperature field as well as in the molar concentrations of the participating species. To assess the accuracy of the WSGG model, the results are compared with a solution obtained by line-by-line integration (LBL) of the spectrum.
Baiz, Carlos R; Schach, Denise; Tokmakoff, Andrei
2014-07-28
We describe a microscope for measuring two-dimensional infrared (2D IR) spectra of heterogeneous samples with ?m-scale spatial resolution, sub-picosecond time resolution, and the molecular structure information of 2D IR, enabling the measurement of vibrational dynamics through correlations in frequency, time, and space. The setup is based on a fully collinear "one beam" geometry in which all pulses propagate along the same optics. Polarization, chopping, and phase cycling are used to isolate the 2D IR signals of interest. In addition, we demonstrate the use of vibrational lifetime as a contrast agent for imaging microscopic variations in molecular environments. PMID:25089490
NASA Astrophysics Data System (ADS)
Martínez, F.; Maksymowicz, A.; Ochoa, H.; Díaz, D.
2015-08-01
This paper discusses an integrated approach that provides new ideas about the structural geometry of the NNE-striking, Cretaceous Chañarcillo Basin located along the eastern Coastal Cordillera in the western Central Andes of northern Chile (27-28° S). The results obtained from the integration of two transverse (E-W) gravity profiles with previous geological information, show that the architecture of this basin is defined by a large NNE-SSE-trending and east-vergent anticline ("Tierra Amarilla Anticlinorium"), which is related to the positive reactivation of a former Cretaceous normal fault (Elisa de Bordos Master Fault). Moreover, intercalations of high and low gravity anomalies and steep gravity gradients reveal a set of buried, west-tilted half-grabens associated with a synthetic normal fault pattern. These results, together with the uplift and folding style of the Cretaceous syn-rift recognized within the basin, suggest that their complete structural geometry could be explained by an inverted fault system linked to the shortening of pre-existing Cretaceous normal fault systems. Ages of the synorogenic deposits exposed unconformably over the frontal limb of the Tierra Amarilla Anticlinorium confirm a Late Cretaceous age for the Andean deformation and tectonic inversion of the basin.
Ouadah, S.; Stayman, J. W.; Gang, G.; Uneri, A.; Ehtiati, T.; Siewerdsen, J. H.
2015-01-01
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 non-circular 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. PMID:26388661
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.
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…
(+)-(R,Z)-5-Muscenone and (-)-(R)-muscone by enantioselective aldol reaction and Grob fragmentation.
Fehr, Charles; Buzas, Andrea K; Knopff, Oliver; de Saint Laumer, Jean-Yves
2010-02-22
(+)-(R,Z)-5-Muscenone ((R)-1) was synthesized by an enantioselective aldol reaction, catalyzed by new ephedrine-type Ti reagents (up to 70 % enantiomeric excess). Substrate-directed diastereoselective reduction of the aldol product and Grob fragmentation of the tosylate of the resultant 1,3-diol afforded (+)-1. This approach also gave access to (-)-(R,E)-5-muscenone and (-)-(R)-muscone. PMID:20077541
Energy Science and Technology Software Center (ESTSC)
2005-07-01
Aniso2d is a two-dimensional seismic forward modeling code. The earth is parameterized by an X-Z plane in which the seismic properties Can have monoclinic with x-z plane symmetry. The program uses a user define time-domain wavelet to produce synthetic seismograms anrwhere within the two-dimensional media.
Energy Science and Technology Software Center (ESTSC)
2011-12-31
Mesh2d is a Fortran90 program designed to generate two-dimensional structured grids of the form [x(i),y(i,j)] where [x,y] are grid coordinates identified by indices (i,j). The x(i) coordinates alone can be used to specify a one-dimensional grid. Because the x-coordinates vary only with the i index, a two-dimensional grid is composed in part of straight vertical lines. However, the nominally horizontal y(i,j0) coordinates along index i are permitted to undulate or otherwise vary. Mesh2d also assignsmore »an integer material type to each grid cell, mtyp(i,j), in a user-specified manner. The complete grid is specified through three separate input files defining the x(i), y(i,j), and mtyp(i,j) variations.« less
NASA Astrophysics Data System (ADS)
Lotsch, Bettina V.
2015-07-01
Graphene's legacy has become an integral part of today's condensed matter science and has equipped a whole generation of scientists with an armory of concepts and techniques that open up new perspectives for the postgraphene area. In particular, the judicious combination of 2D building blocks into vertical heterostructures has recently been identified as a promising route to rationally engineer complex multilayer systems and artificial solids with intriguing properties. The present review highlights recent developments in the rapidly emerging field of 2D nanoarchitectonics from a materials chemistry perspective, with a focus on the types of heterostructures available, their assembly strategies, and their emerging properties. This overview is intended to bridge the gap between two major—yet largely disjunct—developments in 2D heterostructures, which are firmly rooted in solid-state chemistry or physics. Although the underlying types of heterostructures differ with respect to their dimensions, layer alignment, and interfacial quality, there is common ground, and future synergies between the various assembly strategies are to be expected.
MULTI2D - a computer code for two-dimensional radiation hydrodynamics
NASA Astrophysics Data System (ADS)
Ramis, R.; Meyer-ter-Vehn, J.; Ramírez, J.
2009-06-01
Simulation of radiation hydrodynamics in two spatial dimensions is developed, having in mind, in particular, target design for indirectly driven inertial confinement energy (IFE) and the interpretation of related experiments. Intense radiation pulses by laser or particle beams heat high-Z target configurations of different geometries and lead to a regime which is optically thick in some regions and optically thin in others. A diffusion description is inadequate in this situation. A new numerical code has been developed which describes hydrodynamics in two spatial dimensions (cylindrical R-Z geometry) and radiation transport along rays in three dimensions with the 4 ? solid angle discretized in direction. Matter moves on a non-structured mesh composed of trilateral and quadrilateral elements. Radiation flux of a given direction enters on two (one) sides of a triangle and leaves on the opposite side(s) in proportion to the viewing angles depending on the geometry. This scheme allows to propagate sharply edged beams without ray tracing, though at the price of some lateral diffusion. The algorithm treats correctly both the optically thin and optically thick regimes. A symmetric semi-implicit (SSI) method is used to guarantee numerical stability. Program summaryProgram title: MULTI2D Catalogue identifier: AECV_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AECV_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 151 098 No. of bytes in distributed program, including test data, etc.: 889 622 Distribution format: tar.gz Programming language: C Computer: PC (32 bits architecture) Operating system: Linux/Unix RAM: 2 Mbytes Word size: 32 bits Classification: 19.7 External routines: X-window standard library (libX11.so) and corresponding heading files (X11/*.h) are required. Nature of problem: In inertial confinement fusion and related experiments with lasers and particle beams, energy transport by thermal radiation becomes important. Under these conditions, the radiation field strongly interacts with the hydrodynamic motion through emission and absorption processes. Solution method: The equations of radiation transfer coupled with Lagrangian hydrodynamics, heat diffusion and beam tracing (laser or ions) are solved, in two-dimensional axial-symmetric geometry ( R-Z coordinates) using a fractional step scheme. Radiation transfer is solved with angular resolution. Matter properties are either interpolated from tables (equations-of-state and opacities) or computed by user routines (conductivities and beam attenuation). Restrictions: The code has been designed for typical conditions prevailing in inertial confinement fusion (ns time scale, matter states close to local thermodynamical equilibrium, negligible radiation pressure, …). Although a wider range of situations can be treated, extrapolations to regions beyond this design range need special care. Unusual features: A special computer language, called r94, is used at top levels of the code. These parts have to be converted to standard C by a translation program (supplied as part of the package). Due to the complexity of code (hydro-code, grid generation, user interface, graphic post-processor, translator program, installation scripts) extensive manuals are supplied as part of the package. Running time: 567 seconds for the example supplied.
THE STATUS OF TODAYS DESCRIPTIVE GEOMETRY RELATED EDUCATION
Nawratil, Georg
is carried out in European countries. By definition, Descriptive Geometry is a method to study 3D geometry: `Descriptive Geometry' is a method #12;2 to study 3D geometry through 2D images. It provides insight Geometry is the interplay · between the 3D situation and its 2D repre- sentation, and · between intuitive
A Geometric Boolean Library for 2D Objects
Energy Science and Technology Software Center (ESTSC)
2006-01-05
The 2D Boolean Library is a collection of C++ classes -- which primarily represent 2D geometric data and relationships, and routines -- which contain algorithms for 2D geometric Boolean operations and utility functions. Classes are provided for 2D points, lines, arcs, edgeuses, loops, surfaces and mask sets. Routines are provided that incorporate the Boolean operations Union(OR), XOR, Intersection and Difference. Various analytical geometry routines and routines for importing and exporting the data in various filemore »formats, are also provided in the library.« less
NASA Astrophysics Data System (ADS)
Apruzese, J. P.; Giuliani, J. L.
2008-11-01
Radiation plays a critical role in the dynamics of Z-pinch implosions. Modeling of Z-pinch experiments therefore needs to include an accurate but efficient algorithm for photon transport. Such algorithms exist for the one-dimensional (1D) approximation. In the present work, we report progress toward this goal in a 2D (r,z) geometry, intended for use in radiation hydrodynamics calculations of dynamically evolving Z pinches. We have tested a radiation transport algorithm that uses discrete ordinate sets for the ray in 3-space, and the multifrequency integral solution along each ray. The published solutions of Avery et al. [1] for the line source functions are used as a benchmark to ensure the accuracy of our approach. We discuss the coupling between the radiation field and kinetics that results in large departures from LTE, ruling out use of the diffusion approximation. [1] L. W. Avery, L. L. House, and A. Skumanich, JQSRT 9, 519 (1969).
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.
NASA Astrophysics Data System (ADS)
Wang, Jin; Ma, Jianyong; Zhou, Changhe
2014-11-01
A 3×3 high divergent 2D-grating with period of 3.842?m at wavelength of 850nm under normal incidence is designed and fabricated in this paper. This high divergent 2D-grating is designed by the vector theory. The Rigorous Coupled Wave Analysis (RCWA) in association with the simulated annealing (SA) is adopted to calculate and optimize this 2D-grating.The properties of this grating are also investigated by the RCWA. The diffraction angles are more than 10 degrees in the whole wavelength band, which are bigger than the traditional 2D-grating. In addition, the small period of grating increases the difficulties of fabrication. So we fabricate the 2D-gratings by direct laser writing (DLW) instead of traditional manufacturing method. Then the method of ICP etching is used to obtain the high divergent 2D-grating.
Qutb al-D?n Sh?r?z? (1236-1311), Persian polymath physician in the medieval period.
Nadim, Mostafa; Farjam, Mojtaba
2014-05-15
Qutb al-D?n Sh?r?z?, a great physician in the medieval period of the Iranian Islamic age, is also called All?ma (polymath) for his extraordinary expertise in almost all fields of contemporary sciences. The peaceful and cultural environment of his hometown and family contributed to his development despite a time of horror from Mongolian repeated invasions of the Islamic countries. Sh?r?z? never ceased learning and researching and migrated widely in order to find scientists to learn from them. He worked in many centres as a teacher and researcher. He practised medicine and educated students, and his books on other fields of science reflect his comprehensive mastery of most of the basic sciences and the humanities. Sh?r?z??'s social and political roles make him one of the paramount of Iranian elites who contributed to the re-establishment of the Iranian-Islamic civilisation after its destruction by the Mongolians in the thirteenth century. PMID:24833544
Recovering 3D tumor locations from 2D bioluminescence images
Huang, Xiaolei
Recovering 3D tumor locations from 2D bioluminescence images Xiaolei Huang1 , Dimitris Metaxas1 Bioluminescence imaging (BLI) is an emerging technique for sensitive and nonin- vasive imaging, which can be used bioluminescence images, then register and visualize the reconstructed tumor with detailed animal geometry
Optoelectronics with 2D semiconductors
NASA Astrophysics Data System (ADS)
Mueller, Thomas
2015-03-01
Two-dimensional (2D) atomic crystals, such as graphene and layered transition-metal dichalcogenides, are currently receiving a lot of attention for applications in electronics and optoelectronics. In this talk, I will review our research activities on electrically driven light emission, photovoltaic energy conversion and photodetection in 2D semiconductors. In particular, WSe2 monolayer p-n junctions formed by electrostatic doping using a pair of split gate electrodes, type-II heterojunctions based on MoS2/WSe2 and MoS2/phosphorene van der Waals stacks, 2D multi-junction solar cells, and 3D/2D semiconductor interfaces will be presented. Upon optical illumination, conversion of light into electrical energy occurs in these devices. If an electrical current is driven, efficient electroluminescence is obtained. I will present measurements of the electrical characteristics, the optical properties, and the gate voltage dependence of the device response. In the second part of my talk, I will discuss photoconductivity studies of MoS2 field-effect transistors. We identify photovoltaic and photoconductive effects, which both show strong photoconductive gain. A model will be presented that reproduces our experimental findings, such as the dependence on optical power and gate voltage. We envision that the efficient photon conversion and light emission, combined with the advantages of 2D semiconductors, such as flexibility, high mechanical stability and low costs of production, could lead to new optoelectronic technologies.
Compatible, energy and symmetry preserving 2D Lagrangian hydrodynamics in rz-cylindrical coordinates
Shashkov, Mikhail; Wendroff, Burton; Burton, Donald; Barlow, A; Hongbin, Guo
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.
California at Santa Cruz, University of
What is an anomaly? Current Conservation Anomaly in 2-d QED: Schwinger model Current MatrixÂ´alez University of California Â Santa Cruz March 2015 1 / 23 #12;What is an anomaly? Current Conservation Anomaly, in other words quantum corrections break the symmetry. 2 / 23 #12;What is an anomaly? Current Conservation
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.
Yukitaka Ishimoto; Takahiro Murashima; Takashi Taniguchi; Ryoichi Yamamoto
2012-03-31
A family of novel models of liquid on a 2D lattice (2D lattice liquid models) have been proposed as primitive models of soft-material membrane. As a first step, we have formulated them as single-component, single-layered, classical particle systems on a two-dimensional surface with no explicit viscosity. Among the family of the models, we have shown and constructed two stochastic models, a vicious walk model and a flow model, on an isotropic regular lattice and on the rectangular honeycomb lattice of various sizes. In both cases, the dynamics is governed by the nature of the frustration of the particle movements. By simulations, we have found the approximate functional form of the frustration probability, and peculiar anomalous diffusions in their time-averaged mean square displacements in the flow model. The relations to other existing statistical models and possible extensions of the models are also discussed.
Nanoimprint lithography: 2D or not 2D? A review
NASA Astrophysics Data System (ADS)
Schift, Helmut
2015-11-01
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.
*PSD:Position Sensitive Detector GP2D12/GP2D15 Distance Measuring Sensors
Wedeward, Kevin
*PSD:Position Sensitive Detector GP2D12/GP2D15 Distance Measuring Sensors General Purpose Type Distance Measuring Sensors SHARP's GP2D12/GP2D15 are general purpose type distance measuring sensors which -10 to +60°C -10 to +60°C Dissipation current Icc MAX.35mA GP2D12 Distance Measuring SensorsGP2D12/GP2
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
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
Rheological Properties of Quasi-2D Fluids in Microgravity
NASA Technical Reports Server (NTRS)
Stannarius, Ralf; Trittel, Torsten; Eremin, Alexey; Harth, Kirsten; Clark, Noel; Maclennan, Joseph; Glaser, Matthew; Park, Cheol; Hall, Nancy; Tin, Padetha
2015-01-01
In recent years, research on complex fluids and fluids in restricted geometries has attracted much attention in the scientific community. This can be attributed not only to the development of novel materials based on complex fluids but also to a variety of important physical phenomena which have barely been explored. One example is the behavior of membranes and thin fluid films, which can be described by two-dimensional (2D) rheology behavior that is quite different from 3D fluids. In this study, we have investigated the rheological properties of freely suspended films of a thermotropic liquid crystal in microgravity experiments. This model system mimics isotropic and anisotropic quasi 2D fluids [46]. We use inkjet printing technology to dispense small droplets (inclusions) onto the film surface. The motion of these inclusions provides information on the rheological properties of the films and allows the study of a variety of flow instabilities. Flat films have been investigated on a sub-orbital rocket flight and curved films (bubbles) have been studied in the ISS project OASIS. Microgravity is essential when the films are curved in order to avoid sedimentation. The experiments yield the mobility of the droplets in the films as well as the mutual mobility of pairs of particles. Experimental results will be presented for 2D-isotropic (smectic-A) and 2D-nematic (smectic-C) phases.
2D FEM Heat Transfer & E&M Field Code
1992-04-02
TOPAZ and TOPAZ2D are two-dimensional implicit finite element computer codes for heat transfer analysis. TOPAZ2D can also be used to solve electrostatic and magnetostatic problems. The programs solve for the steady-state or transient temperature or electrostatic and magnetostatic potential field on two-dimensional planar or axisymmetric geometries. Material properties may be temperature or potential-dependent and either isotropic or orthotropic. A variety of time and temperature-dependent boundary conditions can be specified including temperature, flux, convection, and radiation. By implementing the user subroutine feature, users can model chemical reaction kinetics and allow for any type of functional representation of boundary conditions and internal heat generation. The programs can solve problems of diffuse and specular band radiation in an enclosure coupled with conduction in the material surrounding the enclosure. Additional features include thermal contact resistance across an interface, bulk fluids, phase change, and energy balances.
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.
2D FEM Heat Transfer & E&M Field Code
Energy Science and Technology Software Center (ESTSC)
1992-04-02
TOPAZ and TOPAZ2D are two-dimensional implicit finite element computer codes for heat transfer analysis. TOPAZ2D can also be used to solve electrostatic and magnetostatic problems. The programs solve for the steady-state or transient temperature or electrostatic and magnetostatic potential field on two-dimensional planar or axisymmetric geometries. Material properties may be temperature or potential-dependent and either isotropic or orthotropic. A variety of time and temperature-dependent boundary conditions can be specified including temperature, flux, convection, and radiation.more »By implementing the user subroutine feature, users can model chemical reaction kinetics and allow for any type of functional representation of boundary conditions and internal heat generation. The programs can solve problems of diffuse and specular band radiation in an enclosure coupled with conduction in the material surrounding the enclosure. Additional features include thermal contact resistance across an interface, bulk fluids, phase change, and energy balances.« less
Choi, Jungwook; Chen, Haorong; Li, Feiran; Yang, Lingming; Kim, Steve S; Naik, Rajesh R; Ye, Peide D; Choi, Jong Hyun
2015-11-01
2D transition metal dichalcogenides (TMDCs) are nanomanufactured using a generalized strategy with self-assembled DNA nanotubes. DNA nanotubes of various lengths serve as lithographic etch masks for the dry etching of TMDCs. The nanostructured TMDCs are studied by atomic force microscopy, photoluminescence, and Raman spectroscopy. This parallel approach can be used to manufacture 2D TMDC nanostructures of arbitrary geometries with molecular-scale precision. PMID:26313027
VECTUM. Irregular 2D Velocity Vector Field Plotting Package
McClurg, F.R.; Mousseau, V.A.
1992-05-04
VECTUM is a NCAR Graphics based package, for generating a plot of an irregular 2D velocity vector field. The program reads an ASCII database of x, y, u, v, data pairs and produces a plot in Computer Graphics Metafile (CGM) format. The program also uses an ASCII parameter file for controlling annotation details such as the plot title, arrowhead style, scale of vectors, windowing, etc. Simple geometry (i.e. lines, arcs, splines) can be defined to be included with the velocity vectors. NCAR Graphics drivers can be used to display the CGM file into PostScript, HPGL, HDF, etc, output.
Purcaru, Elena
2012-01-01
The paper presents a solution for endcoding/decoding DNA information in 2D barcodes. First part focuses on the existing techniques and symbologies in 2D barcodes field. The 2D barcode PDF417 is presented as starting point. The adaptations and optimizations on PDF417 and on DataMatrix lead to the solution - DNA2DBC - DeoxyriboNucleic Acid Two Dimensional Barcode. The second part shows the DNA2DBC encoding/decoding process step by step. In conclusions are enumerated the most important features of 2D barcode implementation for DNA.
(2D)2PCA+(2D)2LDA: a new feature extraction for face recognition
NASA Astrophysics Data System (ADS)
Huang, Guohong
2011-06-01
In this paper, we combine the advantages of (2D)2PCA and (2D)2LDA, and propose a two-stage framework: "(2D)2PCA+(2D)2LDA". In the first stage, a two-directional 2D feature extraction technique, (2D)2PCA, is employed to condense the dimension of image matrix; in the second stage, the two-directional 2D linear discriminant analysis (2D)2LDA is performed in the (2D)2PCA subspace to find the optimal discriminant feature vectors. In addition, the proposed method can take full advantage of the descriptive information and discriminant information of the image. Experiments conducted on ORL and Yale face databases demonstrate the effectiveness and robustness of the proposed method.
Capturing nonlocal effects in 2D granular flows
NASA Astrophysics Data System (ADS)
Kamrin, Ken; Koval, Georg
2013-03-01
There is an industrial need, and a scientific desire, to produce a continuum model that can predict the flow of dense granular matter in an arbitrary geometry. A viscoplastic continuum approach, developed over recent years, has shown some ability to approximate steady flow and stress profiles in multiple inhomogeneous flow environments. However, the model incorrectly represents phenomena observed in the slow, creeping flow regime. As normalized flow-rate decreases, granular stresses are observed to become largely rate-independent and a dominating length-scale emerges in the mechanics. This talk attempts to account for these effects, in the simplified case of 2D, using the notion of nonlocal fluidity, which has proven successful in treating nonlocal effects in emulsions. The idea is to augment the local granular fluidity law with a diffusive second-order term scaled by the particle size, which spreads flowing zones accordingly. Below the yield stress, the local contribution vanishes and the fluidity becomes rate-independent, as we require. We implement the modified law in multiple geometries and validate its flow and stress predictions in multiple geometries compared against discrete particle simulations. In so doing, we demonstrate that the nonlocal relation proposed is satisfied universally in a seemingly geometry-independent fashion.
Bottom-up design of 2D organic photocatalysts for visible-light driven hydrogen evolution.
Wang, Peng; Jiang, Xue; Zhao, Jijun
2016-01-27
To design two-dimensional (2D) organocatalysts, three series of covalent organic frameworks (COFs) are constructed using bottom-up strategies, i.e. molecular selection, tunable linkage, and functionalization. First-principles calculations are performed to confirm their photocatalytic activity under visible light. Two of our constructed 2D COF models (B1 and C3) are identified as a sufficiently efficient organocatalyst for visible light water splitting. The controllable construction of such COFs from suitable organic subunit, linkage, and functional groups paves the way for correlating band edge alignments and geometry parameters of 2D organic materials. Our theoretical prediction not only provides essential insights into designing 2D-COF photocatalysts for water splitting, but also sparks other technological applications for 2D organic materials. PMID:26704386
2D conglomerate crystallization of heptahelicene.
Seibel, Johannes; Zoppi, Laura; Ernst, Karl-Heinz
2014-08-14
Two-dimensional (2D) nucleation and crystallization of the helical aromatic hydrocarbon heptahelicene on the single crystalline copper(100) surface has been studied with scanning tunnelling microscopy. In contrast to previously observed racemic 2D crystals on Cu(111), separation into homochiral domains is observed for Cu(100). PMID:24968343
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.
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...
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.
NETGEN -An Advancing Front 2D/3D-Mesh Generator Based on Abstract Rules
Schoeberl, Joachim
NETGEN - An Advancing Front 2D/3D-Mesh Generator Based on Abstract Rules Joachim Schoberl Abstract In this paper, the algorithms of the automatic mesh generator NETGEN are described. The domain is provided by a Constructive Solid Geometry (CSG). The whole task of 3D mesh generation splits into four subproblems of special
Toward a 2-D magneto-optical trap for polar molecules
NASA Astrophysics Data System (ADS)
Hummon, Matthew; Stuhl, Benjamin; Yeo, Mark; Collopy, Alejandra; Ye, Jun
2012-06-01
The additional structure that arises from the rotational degree of freedom in diatomic molecules makes difficult the adaptation of a traditional atomic magneto-optical trap (MOT) for use with molecules. We describe progress toward development of a 2-D MOT for laser cooled yttrium monoxide molecules based on a resonant LC baseball coil geometry.
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.
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)
The Use of Geometric Properties of 2D Arrays across Development
ERIC Educational Resources Information Center
Gibson, Brett M.; Leichtman, Michelle D.; Costa, Rachel; Bemis, Rhyannon
2009-01-01
Four- to 10-year-old children (n = 50) participated in a 2D search task that included geometry (with- and without lines) and feature conditions. During each of 27 trials, participants watched as a cartoon character hid behind one of three landmarks arranged in a triangle on a computer screen. During feature condition trials, participants could use…
2-d Finite Element Code Postprocessor
Energy Science and Technology Software Center (ESTSC)
1996-07-15
ORION is an interactive program that serves as a postprocessor for the analysis programs NIKE2D, DYNA2D, TOPAZ2D, and CHEMICAL TOPAZ2D. ORION reads binary plot files generated by the two-dimensional finite element codes currently used by the Methods Development Group at LLNL. Contour and color fringe plots of a large number of quantities may be displayed on meshes consisting of triangular and quadrilateral elements. ORION can compute strain measures, interface pressures along slide lines, reaction forcesmore »along constrained boundaries, and momentum. ORION has been applied to study the response of two-dimensional solids and structures undergoing finite deformations under a wide variety of large deformation transient dynamic and static problems and heat transfer analyses.« less
Ginsparg, P.
1991-01-01
These are introductory lectures for a general audience that give an overview of the subject of matrix models and their application to random surfaces, 2d gravity, and string theory. They are intentionally 1.5 years out of date.
Ginsparg, P.
1991-12-31
These are introductory lectures for a general audience that give an overview of the subject of matrix models and their application to random surfaces, 2d gravity, and string theory. They are intentionally 1.5 years out of date.
2D electronic materials for army applications
NASA Astrophysics Data System (ADS)
O'Regan, Terrance; Perconti, Philip
2015-05-01
The record electronic properties achieved in monolayer graphene and related 2D materials such as molybdenum disulfide and hexagonal boron nitride show promise for revolutionary high-speed and low-power electronic devices. Heterogeneous 2D-stacked materials may create enabling technology for future communication and computation applications to meet soldier requirements. For instance, transparent, flexible and even wearable systems may become feasible. With soldier and squad level electronic power demands increasing, the Army is committed to developing and harnessing graphene-like 2D materials for compact low size-weight-and-power-cost (SWAP-C) systems. This paper will review developments in 2D electronic materials at the Army Research Laboratory over the last five years and discuss directions for future army applications.
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.
Nucleation dynamics in 2d cylindrical Ising models and chemotaxis
Bosia, Carla; Corá, Davide
2009-01-01
The aim of our work is to study the effect of geometry variation on nucleation times and to address its role in the context of eukaryotic chemotaxis (i.e. the process which allows cells to identify and follow a gradient of chemical attractant). As a first step in this direction we study the nucleation dynamics of the 2d Ising model defined on a cylindrical lattice whose radius changes as a function of time. Geometry variation is obtained by changing the relative value of the couplings between spins in the compactified (vertical) direction with respect to the horizontal one. This allows us to keep the lattice size unchanged and study in a single simulation the values of the compactification radius which change in time. We show, both with theoretical arguments and numerical simulations that squeezing the geometry allows the system to speed up nucleation times even in presence of a very small energy gap between the stable and the metastable states. We then address the implications of our analysis for directional...
Geometry Dependence of Stellarator Turbulence
H.E. Mynick, P. Xanthopoulos and A.H. Boozer
2009-08-10
Using the nonlinear gyrokinetic code package GENE/GIST, we study the turbulent transport in a broad family of stellarator designs, to understand the geometry-dependence of the microturbulence. By using a set of flux tubes on a given flux surface, we construct a picture of the 2D structure of the microturbulence over that surface, and relate this to relevant geometric quantities, such as the curvature, local shear, and effective potential in the Schrodinger-like equation governing linear drift modes.
Finite Heat conduction in 2D Lattices
Lei Yang; Yang Kongqing
2001-07-30
This paper gives a 2D hamonic lattices model with missing bond defects, when the capacity ratio of defects is enough large, the temperature gradient can be formed and the finite heat conduction is found in the model. The defects in the 2D harmonic lattices impede the energy carriers free propagation, by another words, the mean free paths of the energy carrier are relatively short. The microscopic dynamics leads to the finite conduction in the model.
2d index and surface operators
NASA Astrophysics Data System (ADS)
Gadde, Abhijit; Gukov, Sergei
2014-03-01
In this paper we compute the superconformal index of 2d (2, 2) supersymmetric gauge theories. The 2d superconformal index, a.k.a. flavored elliptic genus, is computed by a unitary matrix integral much like the matrix integral that computes the 4d superconformal index. We compute the 2d index explicitly for a number of examples. In the case of abelian gauge theories we see that the index is invariant under flop transition and under CY-LG correspondence. The index also provides a powerful check of the Seiberg-type duality for non-abelian gauge theories discovered by Hori and Tong. In the later half of the paper, we study half-BPS surface operators in = 2 super-conformal gauge theories. They are engineered by coupling the 2d (2, 2) supersymmetric gauge theory living on the support of the surface operator to the 4d = 2 theory, so that different realizations of the same surface operator with a given Levi type are related by a 2d analogue of the Seiberg duality. The index of this coupled system is computed by using the tools developed in the first half of the paper. The superconformal index in the presence of surface defect is expected to be invariant under generalized S-duality. We demonstrate that it is indeed the case. In doing so the Seiberg-type duality of the 2d theory plays an important role.
NASA Technical Reports Server (NTRS)
Kapoor, Kamlesh; Anderson, Bernhard H.; Shaw, Robert J.
1994-01-01
A two-dimensional computational code, PRLUS2D, which was developed for the reactive propulsive flows of ramjets and scramjets, was validated for two-dimensional shock-wave/turbulent-boundary-layer interactions. The problem of compression corners at supersonic speeds was solved using the RPLUS2D code. To validate the RPLUS2D code for hypersonic speeds, it was applied to a realistic hypersonic inlet geometry. Both the Baldwin-Lomax and the Chien two-equation turbulence models were used. Computational results showed that the RPLUS2D code compared very well with experimentally obtained data for supersonic compression corner flows, except in the case of large separated flows resulting from the interactions between the shock wave and turbulent boundary layer. The computational results compared well with the experiment results in a hypersonic NASA P8 inlet case, with the Chien two-equation turbulence model performing better than the Baldwin-Lomax model.
Optical diffraction from opal-based photonic structures: transition from 2D to 3D regimes
NASA Astrophysics Data System (ADS)
Sinev, Ivan S.; Rybin, Mikhail V.; Samusev, Anton K.; Samusev, Kirill B.; Trofimova, Ekaterina Y.; Kurdukov, Dmitry A.; Golubev, Valery G.; Limonov, Mikhail F.
2012-06-01
We report on experimental and theoretical investigations of light diffraction from opal films of different thickness. A special attention was paid to the transformation of diffraction patterns upon building up the opal structure from two-dimensional (2D) film structure towards bulk three-dimensional (3D) structure. In our setup the diffraction patterns are displayed on a narrow cylindrical screen with a specimen fixed in its center. The diffraction patterns have been studied visually and recorded in different scattering geometries with the films illuminated with white unpolarized light. With increasing number of layers, certain regions of 2D diffraction patterns fade out and finally form diffraction spots characteristic for 3D diffraction. We also found that stacking faults in bulk opals lead to formation of a 2D-like diffraction pattern, i.e. such structure demonstrate 3D to quasi-2D transition in optical properties.
NASA Astrophysics Data System (ADS)
Schuur, Terry J.; Ryzhkov, Alexander V.; Zrni, Dusan S.; Schönhuber, Michael
2001-06-01
An analysis of drop size distributions (DSDs) measured in four very different precipitation regimes is presented and is compared with polarimetric radar measurements. The DSDs are measured by a 2D video disdrometer, which is designed to measure drop size, shape, and fall speed with unprecedented accuracy. The observations indicate that significant DSD variability exists not only from one event to the next, but also within each system. Also, despite having vastly different storm structures and maximum rain rates, large raindrops with diameters greater than 5 mm occurred with each system. By comparing the occurrence of large drops with rainfall intensity, the authors find that the largest median diameters are not always associated with the heaviest rainfall, but are sometimes located either in advance of convective cores or, occasionally, in stratiform regions where rainfall rates are relatively low. Disdrometer and polarimetric radar measurements of radar reflectivity Z, differential reflectivity ZDR, specific differential phase KDP, and R(Z) and R(KDP) rain-rate estimators are compared in detail. Overall agreement is good, but it is found that both R(Z) and R(KDP) underestimate rain rate when the DSD is dominated by small drops and overestimate rain rate when the DSD is dominated by large drops. The results indicate that a classification of different rain types (associated with different DSDs) should be an essential part of polarimetric rainfall estimation. Furthermore, observations suggest that ZDR is a key parameter for making such a distinction. Last, the authors compute and compare maximum and average of gamma shape, slope, and intercept parameters for all four precipitation events. Potential measurement errors with the 2D video disdrometer are also discussed.
TOPAZ2D heat transfer code users manual and thermal property data base
Shapiro, A.B.; Edwards, A.L.
1990-05-01
TOPAZ2D is a two dimensional implicit finite element computer code for heat transfer analysis. This user's manual provides information on the structure of a TOPAZ2D input file. Also included is a material thermal property data base. This manual is supplemented with The TOPAZ2D Theoretical Manual and the TOPAZ2D Verification Manual. TOPAZ2D has been implemented on the CRAY, SUN, and VAX computers. TOPAZ2D can be used to solve for the steady state or transient temperature field on two dimensional planar or axisymmetric geometries. Material properties may be temperature dependent and either isotropic or orthotropic. A variety of time and temperature dependent boundary conditions can be specified including temperature, flux, convection, and radiation. Time or temperature dependent internal heat generation can be defined locally be element or globally by material. TOPAZ2D can solve problems of diffuse and specular band radiation in an enclosure coupled with conduction in material surrounding the enclosure. Additional features include thermally controlled reactive chemical mixtures, thermal contact resistance across an interface, bulk fluid flow, phase change, and energy balances. Thermal stresses can be calculated using the solid mechanics code NIKE2D which reads the temperature state data calculated by TOPAZ2D. A three dimensional version of the code, TOPAZ3D is available. The material thermal property data base, Chapter 4, included in this manual was originally published in 1969 by Art Edwards for use with his TRUMP finite difference heat transfer code. The format of the data has been altered to be compatible with TOPAZ2D. Bob Bailey is responsible for adding the high explosive thermal property data.
Lorenz-Mie theory for 2D scattering and resonance calculations
NASA Astrophysics Data System (ADS)
Gagnon, Denis; Dubé, Louis J.
2015-10-01
This PhD tutorial is concerned with a description of the two-dimensional generalized Lorenz-Mie theory (2D-GLMT), a well-established numerical method used to compute the interaction of light with arrays of cylindrical scatterers. This theory is based on the method of separation of variables and the application of an addition theorem for cylindrical functions. The purpose of this tutorial is to assemble the practical tools necessary to implement the 2D-GLMT method for the computation of scattering by passive scatterers or of resonances in optically active media. The first part contains a derivation of the vector and scalar Helmholtz equations for 2D geometries, starting from Maxwell’s equations. Optically active media are included in 2D-GLMT using a recent stationary formulation of the Maxwell-Bloch equations called steady-state ab initio laser theory (SALT), which introduces new classes of solutions useful for resonance computations. Following these preliminaries, a detailed description of 2D-GLMT is presented. The emphasis is placed on the derivation of beam-shape coefficients for scattering computations, as well as the computation of resonant modes using a combination of 2D-GLMT and SALT. The final section contains several numerical examples illustrating the full potential of 2D-GLMT for scattering and resonance computations. These examples, drawn from the literature, include the design of integrated polarization filters and the computation of optical modes of photonic crystal cavities and random lasers.
Audio-frequency electromagnetic tomography in 2-D
Qiang Zhou; Becker, A.; Morrison, H.F. )
1993-04-01
The mathematical formulation of acoustic diffraction tomography is applied to the problem of low frequency, diffusive electromagnetic (EM) fields. EM tomographic inversion, in two-dimensional (2-D) Cartesian geometry, is illustrated for a crosshole source-receiver configuration. The object function of the conductivity distribution is related to the transformed and filtered data by an inverse Fourier transform in the vertical direction and an inverse Laplace transform in the lateral direction. The reconstructed conductivity image is found to be a band-limited version of the actual conductivity distribution. To stabilize the inversion, a regularized least-squares method is used for image reconstruction. As in the seismic case, the inversion quality can be understood by inspecting the wavenumber domain coverage of the object function. Numerical experiments show that the resolution is better in the vertical direction than in the horizontal and it is also a function of source operating frequency. The position and attitude of the target are recovered well.
Interpretive 2-D treatment of scrape-off-layer plasmas
Umansky, M.; Allen, A.; Daughton, W.
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.
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.; Whitney, K. G.; Clark, R. W.; Jones, B.; Coverdale, C. A.; Ampleford, D. J.; Cuneo, M. E.; Deeney, C.
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.
2D microwave imaging reflectometer electronics
Spear, A. G.; Domier, C. W. Hu, X.; Muscatello, C. M.; Ren, X.; Luhmann, N. C.; Tobias, B. J.
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.
Decoding 2-D Maps by Autocovariance Function.
Pietrogrande, Maria Chiara; Marchetti, Nicola; Dondi, Francesco
2016-01-01
This chapter describes a mathematical approach based on the study of the 2-D autocovariance function (2-D ACVF) useful for decoding the complex signals resulting from the separation of protein mixtures. The method allows to obtain fundamental analytical information hidden in 2-D PAGE maps by spot overlapping, such as the number of proteins present in the sample and the mean standard deviation of the spots, describing the separation performance. In addition, it is possible to identify ordered patterns potentially present in spot positions, which can be related to the chemical composition of the protein mixture, such as post-translational modifications.The procedure was validated on computer-simulated maps and successfully applied to reference maps obtained from literature sources. PMID:26611407
ERIC Educational Resources Information Center
Desseyn, H. O.; And Others
1985-01-01
Compares linear-nonlinear and planar-nonplanar geometry through the valence-shell electron pairs repulsion (V.S.E.P.R.), Mulliken-Walsh, and electrostatic force theories. Indicates that although the V.S.E.P.R. theory has more advantages for elementary courses, an explanation of the best features of the different theories offers students a better…
Capacity and Coding for 2D Channels
Khare, Aparna
2011-02-22
stream_source_info KHARE-THESIS.pdf.txt stream_content_type text/plain stream_size 67325 Content-Encoding ISO-8859-1 stream_name KHARE-THESIS.pdf.txt Content-Type text/plain; charset=ISO-8859-1 CAPACITY AND CODING FOR 2D... CHANNELS A Thesis by APARNA KHARE Submitted to the O?ce of Graduate Studies of Texas A&M University in partial fulflllment of the requirements for the degree of MASTER OF SCIENCE December 2010 Major Subject: Electrical Engineering CAPACITY AND CODING FOR 2D...
3D track initiation in clutter using 2D measurements
NASA Astrophysics Data System (ADS)
Lin, Lin; Kirubarajan, Thiagalingam; Bar-Shalom, Yaakov
2001-11-01
In this paper we present an algorithm for initiating 3-D tracks using range and azimuth (bearing) measurements from a 2-D radar on a moving platform. The work is motivated by the need to track possibly low-flying targets, e.g., cruise missiles, using reports from an aircraft-based surveillance radar. Previous work on this problem considered simple linear motion in a flat earth coordinate frame. Our research extends this to a more realistic scenario where the earth"s curvature is also considered. The target is assumed to be moving along a great circle at a constant altitude. After the necessary coordinate transformations, the measurements are nonlinear functions of the target state and the observability of target altitude is severely limited. The observability, quantified by the Cramer-Rao Lower Bound (CRLB), is very sensitive to the sensor-to-target geometry. The paper presents a Maximum Likelihood (ML) estimator for estimating the target motion parameters in the Earth Centered Earth Fixed coordinate frame from 2-D range and angle measurements. In order to handle the possibility of false measurements and missed detections, which was not considered in, we use the Probabilistic Data Association (PDA) algorithm to weight the detections in a frame. The PDA-based modified global likelihood is optimized using a numerical search. The accuracies obtained by the resulting ML-PDA estimator are quantified using the CRLB for different sensor-target configurations. It is shown that the proposed estimator is efficient, that is, it meets the CRLB. Of particular interest is the achievable accuracy for estimating the target altitude, which is not observed directly by the 2-D radar, but can be only inferred from the range and bearing observations.
Crossing the c=1 barrier in 2D Lorentzian quantum gravity
NASA Astrophysics Data System (ADS)
Ambjørn, J.; Anagnostopoulos, K.; Loll, R.
2000-02-01
In an extension of earlier work we investigate the behavior of two-dimensional (2D) Lorentzian quantum gravity under coupling to a conformal field theory with c>1. This is done by analyzing numerically a system of eight Ising models (corresponding to c=4) coupled to dynamically triangulated Lorentzian geometries. It is known that a single Ising model couples weakly to Lorentzian quantum gravity, in the sense that the Hausdorff dimension of the ensemble of two-geometries is two (as in pure Lorentzian quantum gravity) and the matter behavior is governed by the Onsager exponents. By increasing the amount of matter to eight Ising models, we find that the geometry of the combined system has undergone a phase transition. The new phase is characterized by an anomalous scaling of spatial length relative to proper time at large distances, and as a consequence the Hausdorff dimension is now three. In spite of this qualitative change in the geometric sector, and a very strong interaction between matter and geometry, the critical exponents of the Ising model retain their Onsager values. This provides evidence for the conjecture that the KPZ values of the critical exponents in 2D Euclidean quantum gravity are entirely due to the presence of baby universes. Lastly, we summarize the lessons learned so far from 2D Lorentzian quantum gravity.
Dong, Fan; Xiong, Ting; Sun, Yanjuan; Zhang, Yuxin; Zhou, Ying
2015-05-14
Herein, we report a facile strategy for the creation of 2D layered heterostructures with intimate interfacial contact and exposed reactive facets. The 2D layered heterostructures with intimate contact by sharing the interfacial oxygen atoms and exposed reactive facets endowed the as-prepared BiOIO3/BiOI nanostructures with highly enhanced visible photocatalytic performance for NO removal. PMID:25875135
Pierre Rognon; François Molino; Cyprien Gay
2009-02-13
We describe the geometry of foams squeezed between two solid plates (2D GG foams) in two main asymptotic regimes: fully dry floor tiles and dry pancakes. We predict an abrupt transition between both regimes, with a substantial change in the Plateau border radius. This should be observable in different types of experiments on such 2D GG foams: when foam is being progressively dried or wetted, when it is being squeezed further or stretched, when it coarsens through film breakage or Oswald ripening.
Baby universes in 2d quantum gravity
J. Ambjorn; S. Jain; G. Thorleifsson
1993-03-26
We investigate the fractal structure of $2d$ quantum gravity, both for pure gravity and for gravity coupled to multiple gaussian fields and for gravity coupled to Ising spins. The roughness of the surfaces is described in terms of baby universes and using numerical simulations we measure their distribution which is related to the string susceptibility exponent $\\g_{string}$.
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 ...
Aygun, M.; Sahin, Y.; Boztosun, I.
2007-04-23
In a homogeneous magnetic field, we present the solution of the radial Schroedinger equation for V(r)=-(Z/r) + gr + {lambda}r{sup 2} potential. Within an alternative approach, the asymptotic iteration method, we obtain the energy eigenvalues for any arbitrary magnetic fields. The results obtained by using different Larmor frequencies, wL = 0.1, 0.5, 1, 3, 5, 10, are compared with wL = 0 which corresponds to the non-magnetic field case. We present that this method works for weak and strong magnetic field cases i.e. any Larmor frequencies as well as it gives the energy eigenvalues for any n, m quantum numbers.
Static & Dynamic Response of 2D Solids
Energy Science and Technology Software Center (ESTSC)
1996-07-15
NIKE2D is an implicit finite-element code for analyzing the finite deformation, static and dynamic response of two-dimensional, axisymmetric, plane strain, and plane stress solids. The code is fully vectorized and available on several computing platforms. A number of material models are incorporated to simulate a wide range of material behavior including elasto-placicity, anisotropy, creep, thermal effects, and rate dependence. Slideline algorithms model gaps and sliding along material interfaces, including interface friction, penetration and single surfacemore »contact. Interactive-graphics and rezoning is included for analyses with large mesh distortions. In addition to quasi-Newton and arc-length procedures, adaptive algorithms can be defined to solve the implicit equations using the solution language ISLAND. Each of these capabilities and more make NIKE2D a robust analysis tool.« less
Explicit 2-D Hydrodynamic FEM Program
Energy Science and Technology Software Center (ESTSC)
1996-08-07
DYNA2D* is a vectorized, explicit, two-dimensional, axisymmetric and plane strain finite element program for analyzing the large deformation dynamic and hydrodynamic response of inelastic solids. DYNA2D* contains 13 material models and 9 equations of state (EOS) to cover a wide range of material behavior. The material models implemented in all machine versions are: elastic, orthotropic elastic, kinematic/isotropic elastic plasticity, thermoelastoplastic, soil and crushable foam, linear viscoelastic, rubber, high explosive burn, isotropic elastic-plastic, temperature-dependent elastic-plastic. Themore »isotropic and temperature-dependent elastic-plastic models determine only the deviatoric stresses. Pressure is determined by one of 9 equations of state including linear polynomial, JWL high explosive, Sack Tuesday high explosive, Gruneisen, ratio of polynomials, linear polynomial with energy deposition, ignition and growth of reaction in HE, tabulated compaction, and tabulated.« less
Perturbation theory of 2D decagonal quasicrystals
NASA Astrophysics Data System (ADS)
Peng, Yan-ze; Fan, Tian-you
2002-02-01
A perturbation method for solving elastic 3D problems for 2D decagonal quasicrystals with point groups 10 mm, 1022. overline10m2 and 10/mmm is proposed. We obtain a uniformly valid asymptotic solution of the elastic field by regarding phason field as a perturbation to phonon field and introducing a perturbation parameter ?= R/ cll, where cll and R are elastic constants of phonon field and phonon-phason coupling, respectively. A general solution for the equations of order zero is given in terms of five “harmonic” functions. As a simple application of the above theory, considering an infinite 2D decagonal quasicrystal of point group 10 mm weakened by a circular crack, we obtain the uniformly valid asymptotic solutions up to O( ?2) for the mode I loading.
Stochastic Inversion of 2D Magnetotelluric Data
Energy Science and Technology Software Center (ESTSC)
2010-07-01
The algorithm is developed to invert 2D magnetotelluric (MT) data based on sharp boundary parametrization using a Bayesian framework. Within the algorithm, we consider the locations and the resistivity of regions formed by the interfaces are as unknowns. We use a parallel, adaptive finite-element algorithm to forward simulate frequency-domain MT responses of 2D conductivity structure. Those unknown parameters are spatially correlated and are described by a geostatistical model. The joint posterior probability distribution function ismore »explored by Markov Chain Monte Carlo (MCMC) sampling methods. The developed stochastic model is effective for estimating the interface locations and resistivity. Most importantly, it provides details uncertainty information on each unknown parameter. Hardware requirements: PC, Supercomputer, Multi-platform, Workstation; Software requirements C and Fortan; Operation Systems/version is Linux/Unix or Windows« less
Compact 2-D graphical representation of DNA
NASA Astrophysics Data System (ADS)
Randi?, Milan; Vra?ko, Marjan; Zupan, Jure; Novi?, Marjana
2003-05-01
We present a novel 2-D graphical representation for DNA sequences which has an important advantage over the existing graphical representations of DNA in being very compact. It is based on: (1) use of binary labels for the four nucleic acid bases, and (2) use of the 'worm' curve as template on which binary codes are placed. The approach is illustrated on DNA sequences of the first exon of human ?-globin and gorilla ?-globin.
2-D color code quantum computation
Austin G. Fowler
2011-01-10
We describe in detail how to perform universal fault-tolerant quantum computation on a 2-D color code, making use of only nearest neighbor interactions. Three defects (holes) in the code are used to represent logical qubits. Triple defect logical qubits are deformed into isolated triangular sections of color code to enable transversal implementation of all single logical qubit Clifford group gates. CNOT is implemented between pairs of triple defect logical qubits via braiding.
Bandgaps and directional propagation of elastic waves in 2D square zigzag lattice structures
NASA Astrophysics Data System (ADS)
Wang, Yan-Feng; Wang, Yue-Sheng; Zhang, Chuanzeng
2014-12-01
In this paper we propose various types of two-dimensional (2D) square zigzag lattice structures, and we study their bandgaps and directional propagation of elastic waves. The band structures and the transmission spectra of the systems are calculated by using the finite element method. The effects of the geometry parameters of the 2D-zigzag lattices on the bandgaps are investigated and discussed. The mechanism of the bandgap generation is analyzed by studying the vibration modes at the bandgap edges. Multiple wide complete bandgaps are found in a wide porosity range owing to the separation of the degeneracy by introducing bending arms. The bandgaps are sensitive to the geometry parameters of the systems. The deformed displacement fields of the transient response of finite structures subjected to time-harmonic loads are presented to show the directional wave propagation. The research in this paper is relevant to the practical design of cellular structures with enhanced vibro-acoustics performance.
2D array based on fermat spiral
NASA Astrophysics Data System (ADS)
Martínez, O.; Martín, C. J.; Godoy, G.; Ullate, L. G.
2010-01-01
The main challenge faced by 3D ultrasonic imaging with 2D array transducer is the large number of elements required to achieve an acceptable level of quality in the images. Therefore, the optimization of the array layout to reduce the number of active elements in the aperture has been a research topic in the last years. Nowadays, CMUT array technology has made viable the production of 2D arrays with larger flexibility on elements size, shape and position. This is opening new options in 2D array design, allowing to revise as viable alternatives others layouts that had been studied in the past, like circular and Archimedes spiral layout. In this work the problem of designing an imaging system array with a diameter of 60 ? and a limited number of elements using the Fermat spiral layout has been studied. This study has been done for two different numbers of electronic channels (N = 128 and N = 256). As summary, a general discussion of the results and the most interesting cases are presented.
Lectures on 2D gravity and 2D string theory (TASI 1992)
P. Ginsparg; Gregory Moore
1993-04-05
Emphasis is on 2d target space (c=1 coupled to gravity). Contents: 0. Introduction, Overview, and Purpose 1. Loops and States in Conformal Field Theory 2. 2D Euclidean Quantum Gravity I: Path Integral Approach 3. Brief Review of the Liouville Theory 4. 2D Euclidean Quantum Gravity II: Canonical Approach 5. 2D Critical String Theory 6. Discretized surfaces, matrix models, and the continuum limit 7. Matrix Model Technology I: Method of Orthogonal Polynomials 8. Matrix Model Technology II: Loops on the Lattice 9. Matrix Model Technology III: Free Fermions from the Lattice 10. Loops and States in Matrix Model Quantum Gravity 11. Loops and States in the $c=1$ Matrix Model 12. Fermi Sea Dynamics and Collective Field Theory 13. String scattering in two spacetime dimensions 14. Vertex Operator Calculations and Continuum Methods 15. Achievements, Disappointments, Future Prospects "if you read only one set of lecture notes this year, don't read these."
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.
Driven microswimmers on a 2D substrate: A stochastic towed sled model
NASA Astrophysics Data System (ADS)
Marchegiani, Giampiero; Marchesoni, Fabio
2015-11-01
We investigate, both numerically and analytically, the diffusion properties of a stochastic sled sliding on a substrate, subject to a constant towing force. The problem is motivated by the growing interest in controlling transport of artificial microswimmers in 2D geometries at low Reynolds numbers. We simulated both symmetric and asymmetric towed sleds. Remarkable properties of their mobilities and diffusion constants include sidewise drifts and excess diffusion peaks. We interpret our numerical findings by making use of stochastic approximation techniques.
Takes Electric or Magnetic field data through Inversion process a 2D Distributon
2008-05-01
Program images 2D distributions in electrical conductivity for geophysical applications. The program can treat surface based and cross well measurement geometries, including inductive and grounded source antennas in the quasi-static limit. The algorithm using Krylov iterative methods to solve for the predicted data and model sensitivities. The model update is achieved using a Gauss-newton optimization process for stability. A new line search capability is now included in the algorithm to insure global convergence of the inversion iteration.
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
Periodically sheared 2D Yukawa systems
NASA Astrophysics Data System (ADS)
Kovács, Anikó Zsuzsa; Hartmann, Peter; Donkó, Zoltán
2015-10-01
We present non-equilibrium molecular dynamics simulation studies on the dynamic (complex) shear viscosity of a 2D Yukawa system. We have identified a non-monotonic frequency dependence of the viscosity at high frequencies and shear rates, an energy absorption maximum (local resonance) at the Einstein frequency of the system at medium shear rates, an enhanced collective wave activity, when the excitation is near the plateau frequency of the longitudinal wave dispersion, and the emergence of significant configurational anisotropy at small frequencies and high shear rates.
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.
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.
A 2D driven 3D vessel segmentation algorithm for 3D digital subtraction angiography data
NASA Astrophysics Data System (ADS)
Spiegel, M.; Redel, T.; Struffert, T.; Hornegger, J.; Doerfler, A.
2011-10-01
Cerebrovascular disease is among the leading causes of death in western industrial nations. 3D rotational angiography delivers indispensable information on vessel morphology and pathology. Physicians make use of this to analyze vessel geometry in detail, i.e. vessel diameters, location and size of aneurysms, to come up with a clinical decision. 3D segmentation is a crucial step in this pipeline. Although a lot of different methods are available nowadays, all of them lack a method to validate the results for the individual patient. Therefore, we propose a novel 2D digital subtraction angiography (DSA)-driven 3D vessel segmentation and validation framework. 2D DSA projections are clinically considered as gold standard when it comes to measurements of vessel diameter or the neck size of aneurysms. An ellipsoid vessel model is applied to deliver the initial 3D segmentation. To assess the accuracy of the 3D vessel segmentation, its forward projections are iteratively overlaid with the corresponding 2D DSA projections. Local vessel discrepancies are modeled by a global 2D/3D optimization function to adjust the 3D vessel segmentation toward the 2D vessel contours. Our framework has been evaluated on phantom data as well as on ten patient datasets. Three 2D DSA projections from varying viewing angles have been used for each dataset. The novel 2D driven 3D vessel segmentation approach shows superior results against state-of-the-art segmentations like region growing, i.e. an improvement of 7.2% points in precision and 5.8% points for the Dice coefficient. This method opens up future clinical applications requiring the greatest vessel accuracy, e.g. computational fluid dynamic modeling.
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.
2D-fractal based algorithms for nanoparticles characterization
NASA Astrophysics Data System (ADS)
Bonifazi, Giuseppe; Serranti, Silvia
2014-02-01
Fractal geometry concerns the study of non-Euclidean geometrical figures generated by a recursive sequence of mathematical operations. The proposed 2D-fractal approach was applied to characterise the image structure and texture generated by fine and ultra-fine particles when impacting on a flat surface. The work was developed with reference to particles usually produced by ultra-fine milling addressed to generate nano-particles population. In order to generate different particle populations to utilize in the study, specific milling actions have been thus performed adopting different milling actions and utilising different materials, both in terms of original size class distribution and chemical-physical attributes. The aim of the work was to develop a simple, reliable and low cost analytical set of procedures with the ability to establish correlations between particles detected by fractal characteristics and their milled-induced-properties (i.e. size class distribution, shape, surface properties, etc.). Such logic should constitute the core of a control engine addressed to realize a full monitoring of the milling process as well as to establish correlation between operative parameters, fed and resulting products characteristics.
Defect formation and coarsening in hexagonal 2D curved crystals.
García, Nicolás A; Pezzutti, Aldo D; Register, Richard A; Vega, Daniel A; Gómez, Leopoldo R
2015-02-01
In this work we study the processes of defect formation and coarsening of two-dimensional (2D) curved crystal structures. These processes are found to strongly deviate from their counterparts in flat systems. In curved backgrounds the process of defect formation is deeply affected by the curvature, and at the onset of a phase transition the early density of defects becomes highly inhomogeneous. We observe that even a single growing crystal can produce varying densities of defects depending on its initial position and local orientation with regard to the substrate. This process is completely different from flat space, where grain boundaries are formed due to the impingement of different propagating crystals. Quenching the liquid into the crystal phase leads to the formation of a curved polycrystalline structure, characterized by complex arrays of defects. During annealing, mechanisms of geodesic curvature-driven grain boundary motion and defect annihilation lead to increasing crystalline order. Linear arrays of defects diffuse to regions of high curvature, where they are absorbed by disclinations. At the early stage of coarsening the density of dislocations is insensitive to the geometry while the population of isolated disclinations is deeply affected by curvature. The regions with high curvature act as traps for the diffusion of different structures of defects, including disclinations and domain walls. PMID:25491780
NASA Astrophysics Data System (ADS)
Park, Kwan-Ho; Lee, Soonil; Seo, Won-Seon; Shin, Dong-Kil; Kim, Il-Ho
2014-03-01
Rare-earth-filled skutterudites R z Fe4- x Co x Sb12 (R: Yb, La, Ce) were prepared, and their transport and thermoelectric properties were examined. All specimens showed p-type conduction and exhibited a degenerate semiconductor behavior. R0.9Fe3CoSb12 had lower electrical conductivities and higher Seebeck coefficients than RFe4Sb12, which meant that Co led to charge compensation through electron donations. All specimens had positive Hall coefficients, and their carrier concentrations were decreased by charge compensation with increasing Co substitution. The thermal conductivities of R0.9Fe3CoSb12 were lower than those of RFe4Sb12 due to the decreased carrier concentration, as well as the lattice scattering induced by the substitution of Co for Fe. Yb-filled and La-filled skutterudites showed enhanced thermoelectric figures of merit through charge compensation with Co, but Ce-filled skutterudites did not. Yb2˜3+ and La3+ ions required charge compensation to stabilize their skutterudite phases, but Ce3˜4+ ions did not.
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.
2D quantum gravity from quantum entanglement
Ferdinando Gliozzi
2010-06-24
In quantum systems with many degrees of freedom the replica method is a useful tool to study the entanglement of arbitrary spatial regions. We apply it in a way which allows them to back-react. As a consequence, they become dynamical subsystems whose position, form and extension is determined by their interaction with the whole system. We analyze in particular quantum spin chains described at criticality by a conformal field theory (CFT). Its coupling to the Gibbs' ensemble of all possible subsystems is relevant and drives the system into a new fixed point which is argued to be that of the 2D quantum gravity coupled to this system. Numerical experiments on the critical Ising model show that the new critical exponents agree with those predicted by the formula of Knizhnik, Polyakov and Zamolodchikov.
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.
Heat conduction in 2d nonlinear lattices
A. Lippi; R. Livi
1999-10-26
The divergence of the heat conductivity in the thermodynamic limit is investigated in 2d-lattice models of anharmonic solids with nearest-neighbour interaction from single-well potentials. Two different numerical approaches based on nonequilibrium and equilibrium simulations provide consistent indications in favour of a logarithmic divergence in "ergodic", i.e. highly chaotic, dynamical regimes. Analytical estimates obtained in the framework of linear-response theory confirm this finding, while tracing back the physical origin of this {\\sl anomalous} transport to the slow diffusion of the energy of long-wavelength effective Fourier modes. Finally, numerical evidence of {\\sl superanomalous} transport is given in the weakly chaotic regime, typically found below some energy density threshold.
NASA Astrophysics Data System (ADS)
Hannum, David; Fiksel, G.; Forest, C. B.; Kendrick, R. D.
2007-11-01
The rotating wall machine is a linear screw-pinch built to study the role of different wall boundary conditions on the resistive wall mode (RWM). Its plasma is created by a hexagonal array of electrostatic guns. The central seven guns can be biased to discharge up to 1 kA of current. A probe inserted from the opposite end of the chamber combines magnetic pickup loops with singletip Langmuir electrodes. The loop signals are electronically integrated for a current measurement, while the singletip analysis employs a multivariable fitting routine on the I-V curve to derive the traditional Langmuir measurements. The probe can move over the length of the 1.2-meter long plasma column for 2D profiles of q, Te, ne and Vp in r and z. Individual gun streams are seen to coalesce into a single plasma column, with density peaking in the center even as the plasma edge spreads out to the wall.
Responsive ionic liquidpolymer 2D photonic crystal gas sensors
Asher, Sanford A.
Responsive ionic liquidpolymer 2D photonic crystal gas sensors Natasha L. Smith, Zhenmin Hong and Sanford A. Asher* We developed novel air-stable 2D polymerized photonic crystal (2DPC) sensing materials
Generates 2D Input for DYNA NIKE & TOPAZ
1996-07-15
MAZE is an interactive program that serves as an input and two-dimensional mesh generator for DYNA2D, NIKE2D, TOPAZ2D, and CHEMICAL TOPAZ2D. MAZE also generates a basic template for ISLAND input. MAZE has been applied to the generation of input data to study the response of two-dimensional solids and structures undergoing finite deformations under a wide variety of large deformation transient dynamic and static problems and heat transfer analyses.
MAZE96. Generates 2D Input for DYNA NIKE & TOPAZ
Sanford, L.; Hallquist, J.O.
1992-02-24
MAZE is an interactive program that serves as an input and two-dimensional mesh generator for DYNA2D, NIKE2D, TOPAZ2D, and CHEMICAL TOPAZ2D. MAZE also generates a basic template for ISLAND input. MAZE has been applied to the generation of input data to study the response of two-dimensional solids and structures undergoing finite deformations under a wide variety of large deformation transient dynamic and static problems and heat transfer analyses.
Tracer dispersion in 2-D fractures with flat and rough walls in a radial flow geometry
Hinch, John
Laboratoire de Physique et Mecanique des Milieux He'terogenes (LJRA-CNRS No. 857). ESPCI, 10 rue Vauquelin90, 42003 Saint-Etienne Cedex I, France J. P. Hulin Laboratoire de Physique et Mecanique des Milieux of the geometrical and velocity field structures, fractured media represent an excellent example of heterogeneous
World-Sheet Geometry and Baby Universes in 2-D Quantum Gravity
Sanjay Jain; Samir D. Mathur
1992-04-07
We show that the surface roughness for $cgravity is described by a self-similar structure of baby universes. There exist baby universes whose neck thickness is of the order of the ultraviolet cutoff, the largest of these having a macroscopic area $\\sim A^{1 \\over {1-\\gamma}}$, where $A$ is the total area and $\\gamma$ the string susceptibility exponent.
Communication Ultrafast 2D NMR spectroscopy using a continuous spatial
Frydman, Lucio
Communication Ultrafast 2D NMR spectroscopy using a continuous spatial encoding of the spin by ultrafast 2D NMR spectroscopy. It is found that when dealing with 2D NMR experiments involving a t1 NMR spectra within a single scan is introduced and illustrated. The approach relies on applying a pair
INTRODUCTION Device-to-device (D2D) communications are
Shen, Xuemin "Sherman"
points or base stations. Bluetooth and WiFi-Direct are the two most popular D2D tech- niques, both working in the unlicensed 2.4 GHz industrial, scientific, and medical (ISM) bands. Cellular networks the possibilities of introducing D2D communications in cellular networks [2]. Such network assisted D2D
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.
Lott, Geoffrey A.; Perdomo-Ortiz, Alejandro; 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. Specifically, we studied magnesium meso tetraphenylporphyrin dimers, which form in the amphiphilic regions of 1,2-distearoyl-sn-glycero-3-phosphocholine liposomes. Comparison between experimental and simulated spectra show that although a wide range of dimer conformations can be inferred by either the linear absorption spectrum or the 2D spectrum alone, consideration of both types of spectra constrain the possible structures to a “T-shaped” geometry. These experiments establish the PM-2D FS method as an effective approach to elucidate chromophore dimer conformation. PMID:21940499
Elastic interactions between 2D geometric defects
Michael Moshe; Eran Sharon; Raz Kupferman
2015-10-13
In this paper, we introduce a methodology applicable to a wide range of localized two-dimensional sources of stress. This methodology is based on a geometric formulation of elasticity. Localized sources of stress are viewed as singular defects---point charges of the curvature associated with a reference metric. The stress field in the presence of defects can be solved using a scalar stress function that generalizes the classical Airy stress function to the case of materials with nontrivial geometry. This approach allows the calculation of interaction energies between various types of defects. We apply our methodology to two physical systems: shear-induced failure of amorphous materials and the mechanical interaction between contracting cells.
2D/3D Visual Tracker for Rover Mast
NASA Technical Reports Server (NTRS)
Bajracharya, Max; Madison, Richard W.; Nesnas, Issa A.; Bandari, Esfandiar; Kunz, Clayton; Deans, Matt; Bualat, Maria
2006-01-01
A visual-tracker computer program controls an articulated mast on a Mars rover to keep a designated feature (a target) in view while the rover drives toward the target, avoiding obstacles. Several prior visual-tracker programs have been tested on rover platforms; most require very small and well-estimated motion between consecutive image frames a requirement that is not realistic for a rover on rough terrain. The present visual-tracker program is designed to handle large image motions that lead to significant changes in feature geometry and photometry between frames. When a point is selected in one of the images acquired from stereoscopic cameras on the mast, a stereo triangulation algorithm computes a three-dimensional (3D) location for the target. As the rover moves, its body-mounted cameras feed images to a visual-odometry algorithm, which tracks two-dimensional (2D) corner features and computes their old and new 3D locations. The algorithm rejects points, the 3D motions of which are inconsistent with a rigid-world constraint, and then computes the apparent change in the rover pose (i.e., translation and rotation). The mast pan and tilt angles needed to keep the target centered in the field-of-view of the cameras (thereby minimizing the area over which the 2D-tracking algorithm must operate) are computed from the estimated change in the rover pose, the 3D position of the target feature, and a model of kinematics of the mast. If the motion between the consecutive frames is still large (i.e., 3D tracking was unsuccessful), an adaptive view-based matching technique is applied to the new image. This technique uses correlation-based template matching, in which a feature template is scaled by the ratio between the depth in the original template and the depth of pixels in the new image. This is repeated over the entire search window and the best correlation results indicate the appropriate match. The program could be a core for building application programs for systems that require coordination of vision and robotic motion.
NASA Astrophysics Data System (ADS)
Matsushima, F.; Yonezu, T.; Moriwaki, Y.; Takagi, K.; Amano, T.
2009-06-01
The pure rotational transition frequencies of H_2D^+, 2_{12}? 1_{11}, 2_{02}? 1_{01}, 2_{11}? 1_{10}, and 3_{13}? 2_{12}, have been measured in the laboratory precisely by using a tunable far-infrared spectrometer. Among them, the 2_{12}? 1_{11} line was recently detected in space toward Sgr B2 by Cernicharo et al.^a. Their identification was made based on a calculated line frequency estimated from the spectroscopic data of Amano and Hirao^b. It has been found that our measured frequency of this line, 2363242.82(69) MHz, is lower by about 20 MHz than the estimated value. All the available THz lines and known millimeter- and submillimeter-wave lines together with the combination differences derived from the infrared transitions are fitted to the Watson effective Hamiltonian. A set of improved molecular constants are obtained. ---------- ^aJ.Cernicharo, E. Polehampton, and J.R. Goicoechea. Astrophys. J., 657, L21-L24 (2007). ^bT. Amano and T. Hirao, J. Mol. Spectrosc., 233, 7-14 (2005).
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.
NASA Technical Reports Server (NTRS)
Taylor, Peter R.; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.
1987-01-01
High quality ab initio electonic structure calculations were performed on the 2D Rydberg series in Al I. The configuration 3s3p2(2D) is shown to contribute substantially to the lowest four 2D Rydberg states. The same configuration also contributes substantially to a 2D state embedded in the ionization continuum. Computed oscillator strengths for the first six members of the 2D Rydberg transitions are given: these should be of substantially high accuracy than currently available values.
NASA Technical Reports Server (NTRS)
Taylor, Peter R.; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.
1988-01-01
High-quality ab initio electronic structure calculations have been performed on the 2D Rydberg series in Al I. The configuration 3s3p2(2D) is shown to contribute substantially to the lowest four 2D Rydberg states. The same configuration also contributes substantially to a 2D state embedded in the ionization continuum. Computed oscillator strengths for the first six members of the 2D Rydberg transitions are given: these should be of substantially higher accuracy than currently available values.
GMC Collisions as Triggers of Star Formation. I. Parameter Space Exploration with 2D Simulations
NASA Astrophysics Data System (ADS)
Wu, Benjamin; Van Loo, Sven; Tan, Jonathan C.; Bruderer, Simon
2015-09-01
We utilize magnetohydrodynamic (MHD) simulations to develop a numerical model for giant molecular cloud (GMC)-GMC collisions between nearly magnetically critical clouds. The goal is to determine if, and under what circumstances, cloud collisions can cause pre-existing magnetically subcritical clumps to become supercritical and undergo gravitational collapse. We first develop and implement new photodissociation region based heating and cooling functions that span the atomic to molecular transition, creating a multiphase ISM and allowing modeling of non-equilibrium temperature structures. Then in 2D and with ideal MHD, we explore a wide parameter space of magnetic field strength, magnetic field geometry, collision velocity, and impact parameter and compare isolated versus colliding clouds. We find factors of ˜2-3 increase in mean clump density from typical collisions, with strong dependence on collision velocity and magnetic field strength, but ultimately limited by flux-freezing in 2D geometries. For geometries enabling flow along magnetic field lines, greater degrees of collapse are seen. We discuss observational diagnostics of cloud collisions, focussing on 13CO(J = 2-1), 13CO(J = 3-2), and 12CO(J = 8-7) integrated intensity maps and spectra, which we synthesize from our simulation outputs. We find that the ratio of J = 8-7 to lower-J emission is a powerful diagnostic probe of GMC collisions.
Universal Centrality and Collision Energy Trends for $v_2$ Measurements From 2D Angular Correlations
STAR collaboration; David Kettler
2009-07-15
We have measured the $p_t$-integrated quadrupole component of two-particle azimuth correlations (related to quantity $v_2$, denoted in this case by $v_2 \\{2D\\}$) via two-dimensional (2D) angular autocorrelations on $(\\eta, \\phi)$ for unidentified hadrons in Au-Au collisions at 62 and 200 GeV. The 2D autocorrelation provides a method to remove non-quadrupole contributions to $v_2$ (conventionally termed ``nonflow'') under the assumption that such processes produce significant dependence on pair-wise relative $\\eta$ within the detector acceptance. We hypothesize, based on empirical observations, that non-quadrupole contributions are dominated by minijets or minimum-bias jets. Using the optical Glauber eccentricity model for initial-state geometry we find simple and accurate universal energy and centrality trends for the quadrupole component. Centrality trends are determined only by the initial state (impact parameter $b$ and center-of-mass energy $\\sqrt{s_{NN}}$). There is no apparent dependence on evolving system dynamics (e.g., equation of state or number of secondary collisions). Our measurements of the quadrupole and non-quadrupole components have implications for the contributions to $v_2$. They suggest that the main source of the difference between $v_2 \\{2\\}$ and $v_2 \\{4\\}$ (or $v_2 \\{2D\\}$) is measured properties of minijets.
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.
Simulation of Solar Particle Dropouts in Slab+2D Spherical Harmonic Magnetic Fields
NASA Astrophysics Data System (ADS)
Tooprakai, P.; Ruffolo, D. J.; Matthaeus, W. H.
2011-12-01
The rapid changes in the intensity of solar energetic particles (SEPs) called dropouts, in which the intensity appears and disappears repeatedly, were measured by the ACE spacecraft for impulsive solar flare events and represent the filamentation of the particle distribution. We have explained these features using computer simulations. We evaluate the particle trajectories in slab + 2D spherical harmonic magnetic fields using the fundamental Newton-Lorentz equations in spherical geometry. We simulate the motion of charged particles at different energies in the same magnetic field, which shows that the low energy particles closely follow the slab + 2D spherical harmonic magnetic fields and exhibit dropout features. These features remain and the distribution is even more compact for high energy particles at about 1 AU. Partially supported by NSF SHINE ATM-0752135 and NASA Heliophysics Theory Program NNX08A147G.
2d PDE Linear Symmetric Matrix Solver
Energy Science and Technology Software Center (ESTSC)
1983-10-01
ICCG2 (Incomplete Cholesky factorized Conjugate Gradient algorithm for 2d symmetric problems) was developed to solve a linear symmetric matrix system arising from a 9-point discretization of two-dimensional elliptic and parabolic partial differential equations found in plasma physics applications, such as resistive MHD, spatial diffusive transport, and phase space transport (Fokker-Planck equation) problems. These problems share the common feature of being stiff and requiring implicit solution techniques. When these parabolic or elliptic PDE''s are discretized withmore »finite-difference or finite-element methods,the resulting matrix system is frequently of block-tridiagonal form. To use ICCG2, the discretization of the two-dimensional partial differential equation and its boundary conditions must result in a block-tridiagonal supermatrix composed of elementary tridiagonal matrices. The incomplete Cholesky conjugate gradient algorithm is used to solve the linear symmetric matrix equation. Loops are arranged to vectorize on the Cray1 with the CFT compiler, wherever possible. Recursive loops, which cannot be vectorized, are written for optimum scalar speed. For matrices lacking symmetry, ILUCG2 should be used. Similar methods in three dimensions are available in ICCG3 and ILUCG3. A general source containing extensions and macros, which must be processed by a pre-compiler to obtain the standard FORTRAN source, is provided along with the standard FORTRAN source because it is believed to be more readable. The pre-compiler is not included, but pre-compilation may be performed by a text editor as described in the UCRL-88746 Preprint.« less
2D Geodynamic models of Microcontinent Formation
NASA Astrophysics Data System (ADS)
Tetreault, Joya; Buiter, Susanne
2013-04-01
Continental fragments (microcontinents and continental ribbons) are rifted-off blocks of relatively unthinned continental crust situated among the severely thinned crust of passive margins. The existence of these large crustal blocks would suggest that the passive margin containing them either underwent simultaneous differential rifting or multi-stage rifting in order to produce continental breakup and seafloor spreading in more than one location in the span of approximately 100 km. Also, because continental fragments do not occur on every passive margin, there must be something particular about the crust and/or lithosphere that led to the production of these features. Some proposed mechanisms for microcontinent and continental ribbon formation include (1) structural inheritance, (2) strain localization by serpentinized mantle or magmatic underplating, and (3) plume interaction with an active rift. Pre-existing weakness and inherited structural fabrics in typical continental crust from past tectonic events, such as varying rheology of accreted terranes and collisional suture zones, could be reactivated and serve as foci for deformation. The second theory is that strain is localized in certain regions by large amounts of weakened material that are either serpentinized mantle or mafic bodies underplating the thinned crust. Another possible process that could lead to continental fragment formation is magmatic influence of hot plume material that focuses in various regions, producing rifts in separate areas. The Jan Mayen and Seychelles microcontinents both have geological and plate reconstruction evidence to support the plume interaction theory. We use 2-D geodynamic experiments to assess the importance of structural inheritance, strain localization by regions of weakened mantle material, and contributions to rifting from plume material on producing crustal blocks surrounded by seafloor or thinned/hyperextended crust. Our preliminary results suggest that each of these three mechanisms, working alone, cannot produce concurrent or multi-stage differential thinning and continental break-up. We infer that multistage extension produced by a combination of these mechanisms could be necessary to produce microcontinents and continental ribbons.
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…
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 Å 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.
Automated registration of 3D-range with 2D-color images: an overview
Stamos, Ioannis
Stamos)) Input: Range ImagesInput: Range Images 3D Line Extraction3D Line Extraction Input: 2D ImagesInput: 2D Images 2D Line Extraction2D Line Extraction 3D Line Clustering3D Line Clustering 2D Feature2D Feature Line Extraction3D Line Extraction Input: 2D ImagesInput: 2D Images 2D Line Extraction2D Line Extraction
Additional Invariants and Statistical Equilibria for the 2D Euler Equations on a spherical domain
Herbert, Corentin
2013-01-01
The role of the domain geometry for the statistical mechanics of 2D Euler flows is investigated. It is shown that for a spherical domain, there exists invariant subspaces in phase space which yield additional angular momentum, energy and enstrophy invariants. The microcanonical measure taking into account these invariants is built and a mean-field, Robert-Sommeria-Miller theory is developed in the simple case of the energy-enstrophy measure. The variational problem is solved analytically and a partial energy condensation is obtained. The thermodynamic properties of the system are also discussed.
Takes Electric or Magnetic field data through Inversion process a 2D Distributon
Energy Science and Technology Software Center (ESTSC)
2008-05-01
Program images 2D distributions in electrical conductivity for geophysical applications. The program can treat surface based and cross well measurement geometries, including inductive and grounded source antennas in the quasi-static limit. The algorithm using Krylov iterative methods to solve for the predicted data and model sensitivities. The model update is achieved using a Gauss-newton optimization process for stability. A new line search capability is now included in the algorithm to insure global convergence of themore »inversion iteration.« less
2D-CELL: image processing software for extraction and analysis of 2-dimensional cellular structures
NASA Astrophysics Data System (ADS)
Righetti, F.; Telley, H.; Leibling, Th. M.; Mocellin, A.
1992-01-01
2D-CELL is a software package for the processing and analyzing of photographic images of cellular structures in a largely interactive way. Starting from a binary digitized image, the programs extract the line network (skeleton) of the structure and determine the graph representation that best models it. Provision is made for manually correcting defects such as incorrect node positions or dangling bonds. Then a suitable algorithm retrieves polygonal contours which define individual cells — local boundary curvatures are neglected for simplicity. Using elementary analytical geometry relations, a range of metric and topological parameters describing the population are then computed, organized into statistical distributions and graphically displayed.
Integrated Design for Manufacturing of Braided Preforms for Advanced Composites Part I: 2D Braiding
NASA Astrophysics Data System (ADS)
Gao, Yan Tao; Ko, Frank K.; Hu, Hong
2013-12-01
This paper presents a 2D braiding design system for advanced textile structural composites was based on dynamic models. A software package to assist in the design of braided preform manufacturing has been developed. The package allows design parameters (machine speeds, fiber volume fraction, tightness factor, etc.) to be easily obtained and the relationships between said parameters to be demonstrated graphically. The fabirc geometry model (FGM) method was adopted to evaluate the mechanical properties of the composites. Experimental evidence demonstrates the success of the use of dynamic models in the design software for the manufacture of braided fabric preforms.
Models Ion Trajectories in 2D and 3D Electrostatic and Magnetic Fields
Energy Science and Technology Software Center (ESTSC)
2000-02-21
SIMION3D7.0REV is a C based ion optics simulation program that can model complex problems using Laplace equation solutions for potential fields. The program uses an ion optics workbench that can hold up to 200 2D and/or 3D electrostatic/magnetic potential arrays. Arrays can have up to 50,000,000 points. SIMION3D7.0''s 32 bit virtual Graphics User Interface provides a highly interactive advanced user environment. All potential arrays are visualized as 3D objects that the user can cut awaymore »to inspect ion trajectories and potential energy surfaces. User programs allow the user to customize the program for specific simulations. A geometry file option supports the definition of highly complex array geometry. Algorithm modifications have improved this version''s computational speed and accuracy.« less
Proper time is stochastic time in 2d quantum gravity
J. Ambjorn; R. Loll; Y. Watabiki; W. Westra; S. Zohren
2009-11-21
We show that proper time, when defined in the quantum theory of 2d gravity, becomes identical to the stochastic time associated with the stochastic quantization of space. This observation was first made by Kawai and collaborators in the context of 2d Euclidean quantum gravity, but the relation is even simpler and more transparent in he context of 2d gravity formulated in the framework of CDT (causal dynamical triangulations).
Amoeboid motion in confined geometry
Wu, Hao; Hu, Wei-Fan; Farutin, Alexander; Rafaï, 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...
Complexities of CYP2D6 gene analysis and interpretation.
Gaedigk, Andrea
2013-10-01
Cytochrome P450 2D6 (CYP2D6) plays an important role in the metabolism and bioactivation of about 25% of clinically used drugs including many antidepressants, antipsychotics and opioids. CYP2D6 activity is highly variably ranging from no activity in so-called poor metabolizers to ultrarapid metabolism at the other end of the extreme of the activity distribution. A large portion of this variability can be explained by the highly polymorphic nature of the CYP2D6 gene locus for which > 100 variants and subvariants identified to date. Allele frequencies vary markedly between ethnic groups; some have exclusively or predominantly only been observed in certain populations. Pharmacogenetic testing holds the promise of individualizing drug therapy by identifying patients with CYP2D6 diplotypes that puts them at an increased risk of experiencing dose-related adverse events or therapeutic failure. Inferring a patient's CYP2D6 metabolic capacity, or phenotype, however, is a challenging task due to the complexity of the CYP2D6 gene locus. Allelic variation includes SNPs, small insertions and deletions, gene copy number variation and rearrangements with CYP2D7, a highly related non-functional gene. This review provides a summary of the intricacies of CYP2D6 variation and genotype analysis, knowledge that is invaluable for the translation of genotype into clinically useful information. PMID:24151800
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
Buechler, H. P.; Micheli, A.; Pupillo, G.; Zoller, P.; Demler, E.; Lukin, M.; Prokof'ev, N.
2007-02-09
We discuss techniques to tune and shape the long-range part of the interaction potentials in quantum gases of bosonic polar molecules by dressing rotational excitations with static and microwave fields. This provides a novel tool towards engineering strongly correlated quantum phases in combination with low-dimensional trapping geometries. As an illustration, we discuss the 2D superfluid-crystal quantum phase transition for polar molecules interacting via an electric-field-induced dipole-dipole potential.
Discovering Planetary Nebula Geometries: Explorations with a Hierarchy of Models
Discovering Planetary Nebula Geometries: Explorations with a Hierarchy of Models Karen A. Huyser Naval Observatory, Washington DC 20016 USA Abstract. Astronomical objects known as planetary nebulae for a hierarchy of five models. The first three models treat the nebula as a 2D image, estimating its position
Practical Linear Algebra: A Geometry Toolbox Third edition
Farin, Gerald
to the ancient Greeks An indispensable tool in many applications -- computer graphics -- finite element analysis 2 / 26 #12;Introduction to Breaking It Up: Triangles 2D finite element method: refinementPractical Linear Algebra: A Geometry Toolbox Third edition Chapter 17: Breaking It Up: Triangles
An Evaluation of Multimodal 2D+3D Face Biometrics
Bowyer, Kevin W.
. Flynn Abstract--We report on the largest experimental study to date in multimodal 2D+3D face recognition for multimodal recognition. Major conclusions are: 1) 2D and 3D have similar recognition performance when improvement. Index Terms--Biometrics, face recognition, three-dimensional face, multimodal, multisample. æ 1
Integrating Mobile Multimedia into Textbooks: 2D Barcodes
ERIC Educational Resources Information Center
Uluyol, Celebi; Agca, R. Kagan
2012-01-01
The major goal of this study was to empirically compare text-plus-mobile phone learning using an integrated 2D barcode tag in a printed text with three other conditions described in multimedia learning theory. The method examined in the study involved modifications of the instructional material such that: a 2D barcode was used near the text, the…
Tamoxifen and CYP2D6: A Contradiction of Data
Hertz, Daniel L.; McLeod, Howard L.
2012-01-01
Tamoxifen is an effective antiestrogen used in the treatment of hormone receptor–positive breast cancer. Bioconversion of tamoxifen to endoxifen, its most abundant active metabolite, is primarily dependent on the activity of cytochrome P450 2D6 (CYP2D6), which is highly polymorphic. Over 20 published studies have reported on the potential association between CYP2D6 polymorphism and tamoxifen treatment outcome, with highly inconsistent results. The purpose of this review is to explore differences among 17 independent studies to identify factors that may have contributed to the discrepant findings. This report discusses six putative factors that are grouped into two categories: (a) clinical management criteria: hormone receptor classification, menopausal status, and tamoxifen combination therapy; (b) pharmacologic criteria: genotyping comprehensiveness, CYP2D6 inhibitor coadministration, and tamoxifen adherence. Comparison of these factors between the positive and negative studies suggests that tamoxifen combination therapy, genotyping comprehensiveness, and CYP2D6 inhibitor coadministration may account for some of the contradictory results. Future association studies on the link between CYP2D6 genotype and tamoxifen treatment efficacy should account for combination therapy and CYP2D6 inhibition, and interrogate as many CYP2D6 alleles as possible. PMID:22531359
A shading pipeline for 2D animation techniques HEDLENA BEZERRA
de Figueiredo, Luiz Henrique
A shading pipeline for 2D animation techniques HEDLENA BEZERRA 1 , LUIZ VELHO 2 , BRUNO FEIJÓ 1 1] Normals; [O] Orientation; [S] Smoothing; [M] Mask; [I] Interpolation 1. Introduction Traditional animation is often leaded by 2D cartoons where each frame is hand draw. Throughout the history of cartoon
ERIC Educational Resources Information Center
McDonald, Nathaniel J.
2001-01-01
Chronicles a teacher's first year teaching geometry at the Hershey Montessori Farm School in Huntsburg, Ohio. Instructional methods relied on Euclid primary readings and combined pure abstract logic with practical applications of geometry on the land. The course included geometry background imparted by Montessori elementary materials as well as…
Developing Mobile BIM/2D Barcode-Based Automated Facility Management System
Chen, Yen-Pei
2014-01-01
Facility management (FM) has become an important topic in research on the operation and maintenance phase. Managing the work of FM effectively is extremely difficult owing to the variety of environments. One of the difficulties is the performance of two-dimensional (2D) graphics when depicting facilities. Building information modeling (BIM) uses precise geometry and relevant data to support the facilities depicted in three-dimensional (3D) object-oriented computer-aided design (CAD). This paper proposes a new and practical methodology with application to FM that uses an integrated 2D barcode and the BIM approach. Using 2D barcode and BIM technologies, this study proposes a mobile automated BIM-based facility management (BIMFM) system for FM staff in the operation and maintenance phase. The mobile automated BIMFM system is then applied in a selected case study of a commercial building project in Taiwan to verify the proposed methodology and demonstrate its effectiveness in FM practice. The combined results demonstrate that a BIMFM-like system can be an effective mobile automated FM tool. The advantage of the mobile automated BIMFM system lies not only in improving FM work efficiency for the FM staff but also in facilitating FM updates and transfers in the BIM environment. PMID:25250373
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.
Chukalovsky, A. A.; Rakhimova, T. V.; Klopovsky, K. S.; Mankelevich, Yu. A.; Proshina, O. V.
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
A. Cardinali; F. Paoletti; S. Bernabei
1999-05-01
A state of the art numerical tool has been developed to simulate the propagation and the absorption of coexisting different types of waves in a tokamak geometry. The code includes a numerical solution of the three-dimensional (R, Z, {Phi}) toroidal wave equation for the electric field of the different waves in the WKBJ approximation. At each step of integration, the two-dimensional (v{sub {parallel}}, v{sub {perpendicular}}) Fokker-Planck equation is solved in the presence of quasilinear diffusion coefficients. The electron Landau damping of the waves is modeled taking into account the interaction of the wave electric fields with the quasilinearly modified distribution function. Consistently, the code calculates the radial profiles of non-inductively generated current densities, the transmitted power traces and the total power damping curves. Synergistic effects among the different type of waves (e.g., lower hybrid and ion Bernstein waves) are studied through the separation of the contributions of the single wave from the effects due to their coexistence.
Yuri A. Rylov
2005-03-14
The first crisis in the geometry arose in the beginning of XIXth century, when the mathematicians rejected the non-Euclidean geometry as a possible geometry of the real world. Now we observe unreasonable rejection of the non-Riemannian geometry by the official representatives of the contemporary geometry. Class of the Riemannian geometries appears to be too narrow for physical applications. The microcosm physics needs expansion of the class of possible geometries appropriate for the role of space-time geometry. In the framework of the non-Riemannian geometry one can construct the space-time geometry, where the motion of free particles is primordially stochastic, and this stochasticity depends on the particle mass. At the same time the geometry in itself is not stochastic in the sense that the space-time intervals are deterministic. Principles of quantum mechanics can be deduced from such a space-time geometry. The crisis situation in geometry appears to be connected with some preconceptions concerning the foundation of the geometry. The preconceptions as well as the crisis generated by them are not purely scientific phenomena. The human factor (social aspect) is rather strong in the crisis phenomena. The preconceptions and the human factor appear to be so strong, that usual logical arguments are not perceived, and the usual formal mathematical language appears to be inappropriate for perception of an analysis of the crisis origin and of a possibility of its overcoming. In the paper the history and motives of the non-Riemannian geometry construction are presented. There is a hope that such a less formal way of presentation helps to understand and to overcome the existing preconceptions.
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.
The geometry and forcefield of acetylene
NASA Astrophysics Data System (ADS)
Carter, Stuart; Handy, Nicholas C.
The variational method has been used to determine the geometry and ground state potential surface of acetylene. All the parameters were refined through a least-squares fit to J = 0, 1 levels for C2H2 and C2D2. A new program was written to evaluate the rovibrational energy levels; in particular, primitive basis sets were developed for all values of J taking into account the singularity for linear geometries. Thus ?, ?, ?states can be refined. The full theory for tetraatomic linear molecules is presented. In this refinement 150 observed levels were used as data, below 10 000 cm-1. The geometry was refined and gives Re (CC) = 1.2028 Å, Re (CH) = 1.0618 Å, to be compared with the best experimentally derived values of 1.2027 ± 0.0005 Å, 1.062 ± 0.001 Å, respectively. The zero point energies are 5771.1 cm-1 for C2H2and 4571.1 cm-1 for C2D2.
2D vs. 3D mammography observer study
NASA Astrophysics Data System (ADS)
Fernandez, James Reza F.; Hovanessian-Larsen, Linda; Liu, Brent
2011-03-01
Breast cancer is the most common type of non-skin cancer in women. 2D mammography is a screening tool to aid in the early detection of breast cancer, but has diagnostic limitations of overlapping tissues, especially in dense breasts. 3D mammography has the potential to improve detection outcomes by increasing specificity, and a new 3D screening tool with a 3D display for mammography aims to improve performance and efficiency as compared to 2D mammography. An observer study using a mammography phantom was performed to compare traditional 2D mammography with this ne 3D mammography technique. In comparing 3D and 2D mammography there was no difference in calcification detection, and mass detection was better in 2D as compared to 3D. There was a significant decrease in reading time for masses, calcifications, and normals in 3D compared to 2D, however, as well as more favorable confidence levels in reading normal cases. Given the limitations of the mammography phantom used, however, a clearer picture in comparing 3D and 2D mammography may be better acquired with the incorporation of human studies in the future.
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.
Comparison of 2D and 3D gamma analyses
Pulliam, Kiley B.; Huang, Jessie Y.; Howell, Rebecca M.; Followill, David; Kry, Stephen F.; Bosca, Ryan; O’Daniel, Jennifer
2014-02-15
Purpose: As clinics begin to use 3D metrics for intensity-modulated radiation therapy (IMRT) quality assurance, it must be noted that these metrics will often produce results different from those produced by their 2D counterparts. 3D and 2D gamma analyses would be expected to produce different values, in part because of the different search space available. In the present investigation, the authors compared the results of 2D and 3D gamma analysis (where both datasets were generated in the same manner) for clinical treatment plans. Methods: Fifty IMRT plans were selected from the authors’ clinical database, and recalculated using Monte Carlo. Treatment planning system-calculated (“evaluated dose distributions”) and Monte Carlo-recalculated (“reference dose distributions”) dose distributions were compared using 2D and 3D gamma analysis. This analysis was performed using a variety of dose-difference (5%, 3%, 2%, and 1%) and distance-to-agreement (5, 3, 2, and 1 mm) acceptance criteria, low-dose thresholds (5%, 10%, and 15% of the prescription dose), and data grid sizes (1.0, 1.5, and 3.0 mm). Each comparison was evaluated to determine the average 2D and 3D gamma, lower 95th percentile gamma value, and percentage of pixels passing gamma. Results: The average gamma, lower 95th percentile gamma value, and percentage of passing pixels for each acceptance criterion demonstrated better agreement for 3D than for 2D analysis for every plan comparison. The average difference in the percentage of passing pixels between the 2D and 3D analyses with no low-dose threshold ranged from 0.9% to 2.1%. Similarly, using a low-dose threshold resulted in a difference between the mean 2D and 3D results, ranging from 0.8% to 1.5%. The authors observed no appreciable differences in gamma with changes in the data density (constant difference: 0.8% for 2D vs 3D). Conclusions: The authors found that 3D gamma analysis resulted in up to 2.9% more pixels passing than 2D analysis. It must be noted that clinical 2D versus 3D datasets may have additional differences—for example, if 2D measurements are made with a different dosimeter than 3D measurements. Factors such as inherent dosimeter differences may be an important additional consideration to the extra dimension of available data that was evaluated in this study.
Seven-degree-of-freedom, quantum scattering dynamics study of the H2D++H2 reaction
NASA Astrophysics Data System (ADS)
Wang, Dunyou; Xie, Zhen; Bowman, Joel M.
2010-02-01
A quantum scattering dynamics, time-dependent wavepacket propagation method is applied to study the reaction of H2D++H2?H3++HD on the Xie-Braams-Bowman potential energy surface. The reduced-dimensional, seven-degree-of-freedom approach is employed in this calculation by fixing one Jacobi and one torsion angle related to H2D+ at the lowest saddle point geometry of D2d on the potential energy surface. Initial state selected reaction probabilities are presented for various initial rovibrational states. The ground state reaction probability shows no threshold for this reaction, in other words, this reaction can occur without an activation barrier. The vibrational excitation shows that the stretching motion of H+-HD only has a small effect on the reaction probability; the vibrational excitation of HD in H2D+ hinders the reactivity. By contrast, rotational excitation of H+-HD greatly enhances the reactivity with the reaction probability increased double or triple at high rotational states compared to the ground state. Reactive resonances, seen in all the initial state selected reaction probabilities, are also found in the integral cross section for the ground state of H2D+ and H2. The thermal rate coefficient is also calculated and is found to be in semiquantitative agreement with experiment; however, quantum scattering approaches including more degrees of freedom, especially including all the angles, are necessary to study this reaction in the future.
Generation of high quality 2D meshes for given bathymetry
Colmenero, Jorge, S.B. Massachusetts Institute of Technology
2014-01-01
This thesis develops and applies a procedure to generate high quality 2D meshes for any given ocean region with complex coastlines. The different criteria used in determining mesh element sizes for a given domain are ...
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.
Ultralow Electron Temperatures in 2D Electron Gases
ZumbÃ¼hl, Dominik
Ultralow Electron Temperatures in 2D Electron Gases by efficient silver sinter heat exchangers 3.1 Cold Electrons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.2 Kapitza . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.4 Thermal Conduction in Metals . . . . . . . . . . . . . . . . . . . . . 9 3.5 Electron
Collective excitations in 2D hard-disc fluid.
Huerta, Adrian; Bryk, Taras; Trokhymchuk, Andrij
2015-07-01
Collective dynamics of a two-dimensional (2D) hard-disc fluid was studied by molecular dynamics simulations in the range of packing fractions that covers states up to the freezing. Some striking features concerning collective excitations in this system were observed. In particular, the short-wavelength shear waves while being absent at low packing fractions were observed in the range of high packing fractions, just before the freezing transition in a 2D hard-disc fluid. In contrast, the so-called "positive sound dispersion" typically observed in dense Lennard-Jones-like fluids, was not detected for the 2D hard-disc fluid. The ratio of specific heats in the 2D hard-disc fluid shows a monotonic increase with density approaching the freezing, resembling in this way the similar behavior in the vicinity of the Widom line in the case of supercritical fluids. PMID:25595625
Conformal field theory of critical Casimir interactions in 2D
Bimonte, Giuseppe
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 ...
Recent developments in 2D layered inorganic nanomaterials for sensing.
Kannan, Padmanathan Karthick; Late, Dattatray J; Morgan, Hywel; Rout, Chandra Sekhar
2015-08-28
Two dimensional layered inorganic nanomaterials (2D-LINs) have recently attracted huge interest because of their unique thickness dependent physical and chemical properties and potential technological applications. The properties of these layered materials can be tuned via both physical and chemical processes. Some 2D layered inorganic nanomaterials like MoS2, WS2 and SnS2 have been recently developed and employed in various applications, including new sensors because of their layer-dependent electrical properties. This article presents a comprehensive overview of recent developments in the application of 2D layered inorganic nanomaterials as sensors. Some of the salient features of 2D materials for different sensing applications are discussed, including gas sensing, electrochemical sensing, SERS and biosensing, SERS sensing and photodetection. The working principles of the sensors are also discussed together with examples. PMID:26204797
Recent developments in 2D layered inorganic nanomaterials for sensing
NASA Astrophysics Data System (ADS)
Kannan, Padmanathan Karthick; Late, Dattatray J.; Morgan, Hywel; Rout, Chandra Sekhar
2015-08-01
Two dimensional layered inorganic nanomaterials (2D-LINs) have recently attracted huge interest because of their unique thickness dependent physical and chemical properties and potential technological applications. The properties of these layered materials can be tuned via both physical and chemical processes. Some 2D layered inorganic nanomaterials like MoS2, WS2 and SnS2 have been recently developed and employed in various applications, including new sensors because of their layer-dependent electrical properties. This article presents a comprehensive overview of recent developments in the application of 2D layered inorganic nanomaterials as sensors. Some of the salient features of 2D materials for different sensing applications are discussed, including gas sensing, electrochemical sensing, SERS and biosensing, SERS sensing and photodetection. The working principles of the sensors are also discussed together with examples.
Mesoscopic organic nanosheets peeled from stacked 2D covalent frameworks.
Zhang, Yugen; Tan, Meixuan; Li, Hai; Zheng, Yuangang; Gao, Shujun; Zhang, Hua; Ying, Jackie Y
2011-07-14
Novel mesoscopic organic nanosheets were developed by functionalizing bulk 2D organic covalent framework polymers with small molecules. The water-soluble fluorescent nanosheets are promising as nanocarriers for biological applications. PMID:21643599
Chemical vapour deposition: Transition metal carbides go 2D
NASA Astrophysics Data System (ADS)
Gogotsi, Yury
2015-11-01
The unique properties of 2D materials, such as graphene or transition metal dichalcogenides, have been attracting much attention in the past decade. Now, metallically conductive and even superconducting transition metal carbides are entering the game.
2D and 3D ordered arrays of Co magnetic nanowires
NASA Astrophysics Data System (ADS)
Garcia, J.; Prida, V. M.; Vega, V.; Rosa, W. O.; Caballero-Flores, R.; Iglesias, L.; Hernando, B.
2015-06-01
Cobalt nanowire arrays spatially distributed in 2D and 3D arrangements have been performed by pulsed electrodeposition into the pores of planar and cylindrical nanoporous anodic alumina membranes, respectively. Morphological characterization points out the good filling factor reached by electroplated Co nanowires in both kinds of alumina membranes exhibiting hexagonally self-ordered porous structures. Co nanowires grown in both kinds of alumina templates exhibit the same crystalline phases. DC magnetometry and First Order Reversal Curve (FORC) analysis were carried out in order to determine the overall magnetic behavior for both nanowire array geometries. It is found that when the Co nanowires of two kinds of arrays are perpendicularly magnetized, both hysteresis loops are identical, suggesting that neither the intrinsic magnetic behavior of the nanowires nor the collective one depend on the arrays geometry. FORC analysis performed along the radial direction of the Co nanowire arrays embedded in the cylindrical alumina template reveals that the contribution of each nanowire to the magnetization reversal process involves its specific orientation with respect to the applied field direction. Furthermore, the comparison between the magnetic properties for both kinds of Co nanowire arrays allows discussing about the effect of the cylindrical geometry of the template on the magnetostatic interaction among nanowires.
Phylogenetic tree construction based on 2D graphical representation
NASA Astrophysics Data System (ADS)
Liao, Bo; Shan, Xinzhou; Zhu, Wen; Li, Renfa
2006-04-01
A new approach based on the two-dimensional (2D) graphical representation of the whole genome sequence [Bo Liao, Chem. Phys. Lett., 401(2005) 196.] is proposed to analyze the phylogenetic relationships of genomes. The evolutionary distances are obtained through measuring the differences among the 2D curves. The fuzzy theory is used to construct phylogenetic tree. The phylogenetic relationships of H5N1 avian influenza virus illustrate the utility of our approach.
Application of 2-D graphical representation of DNA sequence
NASA Astrophysics Data System (ADS)
Liao, Bo; Tan, Mingshu; Ding, Kequan
2005-10-01
Recently, we proposed a 2-D graphical representation of DNA sequence [Bo Liao, A 2-D graphical representation of DNA sequence, Chem. Phys. Lett. 401 (2005) 196-199]. Based on this representation, we consider properties of mutations and compute the similarities among 11 mitochondrial sequences belonging to different species. The elements of the similarity matrix are used to construct phylogenic tree. Unlike most existing phylogeny construction methods, the proposed method does not require multiple alignment.
2D microscopic model of graphene fracture properties
NASA Astrophysics Data System (ADS)
Hess, Peter
2015-05-01
An analytical two-dimensional (2D) microscopic fracture model based on Morse-type interaction is derived containing no adjustable parameter. From the 2D Young’s moduli and 2D intrinsic strengths of graphene measured by nanoindentation based on biaxial tension and calculated by density functional theory for uniaxial tension the widely unknown breaking force, line or edge energy, surface energy, fracture toughness, and strain energy release rate were determined. The simulated line energy agrees well with ab initio calculations and the fracture toughness of perfect graphene sheets is in good agreement with molecular dynamics simulations and the fracture toughness evaluated for defective graphene using the Griffith relation. Similarly, the estimated critical strain energy release rate agrees well with result of various theoretical approaches based on the J-integral and surface energy. The 2D microscopic model, connecting 2D and three-dimensional mechanical properties in a consistent way, provides a versatile relationship to easily access all relevant fracture properties of pristine 2D solids.
Geometry of Thin Nematic Elastomer Sheets
NASA Astrophysics Data System (ADS)
Aharoni, Hillel; Sharon, Eran; Kupferman, Raz
2014-12-01
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.
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.
Failure Mechanism of True 2D Granular Flows
Nguyen, Cuong T; Fukagawa, R
2015-01-01
Most previous experimental investigations of two-dimensional (2D) granular column collapses have been conducted using three-dimensional (3D) granular materials in narrow horizontal channels (i.e., quasi-2D condition). Our recent research on 2D granular column collapses by using 2D granular materials (i.e., aluminum rods) has revealed results that differ markedly from those reported in the literature. We assume a 2D column with an initial height of h0 and initial width of d0, a defined as their ratio (a =h0/d0), a final height of h , and maximum run-out distance of d . The experimental data suggest that for the low a regime (a 0.65), the ratio of a to (d-d0)/d0, h0/h , or d/d0 is expressed by power-law relations. In particular, the following power-function ratios (h0/h=1.42a^2/3 and d/d0=4.30a^0.72) are proposed for every a >0.65. In contrast, the ratio (d-d0)/d0=3.25a^0.96 only holds for 0.651.5. In addition, the influence of ground contact surfaces (hard or soft beds) on the final run-out distance and destru...
Transient 2D IR spectroscopy of ubiquitin unfolding dynamics
Chung, Hoi Sung; Ganim, Ziad; Jones, Kevin C.; Tokmakoff, Andrei
2007-01-01
Transient two-dimensional infrared (2D IR) spectroscopy is used as a probe of protein unfolding dynamics in a direct comparison of fast unfolding experiments with molecular dynamics simulations. In the experiments, the unfolding of ubiquitin is initiated by a laser temperature jump, and protein structural evolution from nanoseconds to milliseconds is probed using amide I 2D IR spectroscopy. The temperature jump prepares a subensemble near the unfolding transition state, leading to quasi-barrierless unfolding (the “burst phase”) before the millisecond activated unfolding kinetics. The burst phase unfolding of ubiquitin is characterized by a loss of the coupling between vibrations of the ?-sheet, a process that manifests itself in the 2D IR spectrum as a frequency blue-shift and intensity decrease of the diagonal and cross-peaks of the sheet's two IR active modes. As the sheet unfolds, increased fluctuations and solvent exposure of the ?-sheet amide groups are also characterized by increases in homogeneous linewidth. Experimental spectra are compared with 2D IR spectra calculated from the time-evolving structures in a molecular dynamics simulation of ubiquitin unfolding. Unfolding is described as a sequential unfolding of strands in ubiquitin's ?-sheet, using two collective coordinates of the sheet: (i) the native interstrand contacts between adjacent ?-strands I and II and (ii) the remaining ?-strand contacts within the sheet. The methods used illustrate the general principles by which 2D IR spectroscopy can be used for detailed dynamical comparisons of experiment and simulation. PMID:17551015
Growth and Characterization of Silicon at the 2D Limit
NASA Astrophysics Data System (ADS)
Mannix, Andrew; Kiraly, Brian; Hersam, Mark; Guisinger, Nathan
2015-03-01
Because bulk silicon has dominated the development of microelectronics over the past 50 years, the recent interest in two-dimensional (2D) materials (e.g., graphene, MoS2, phosphorene, etc.) naturally raises questions regarding the growth and properties of silicon at the 2D limit. Utilizing atomic-scale, ultra-high vacuum (UHV) scanning tunneling microscopy (STM), we have investigated the 2D limits of silicon growth on Ag(111). In agreement with previous reports of sp2-bonded silicene phases, we observe the temperature-dependent evolution of ordered 2D phases. However, we attribute these to apparent Ag-Si surface alloys. At sufficiently high silicon coverage, we observe the precipitation of crystalline, sp3-bonded Si(111) domains. These domains are capped with a ?3 honeycomb phase that is indistinguishable from the silver-induced ?3 honeycomb-chained-trimer reconstruction on bulk Si(111). Further ex-situcharacterization with Raman spectroscopy, atomic force microscopy, cross-sectional transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy reveals that these sheets are ultrathin sheets of bulk-like, (111) oriented, sp3 silicon. Even at the 2D limit, scanning tunneling spectroscopy shows that these silicon nanosheets exhibit semiconducting electronic characteristics.
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.
Toward an Efficient Icing CFD Process Using an Interactive Software Toolkit: Smagglce 2D
NASA Technical Reports Server (NTRS)
Vickerman, Mary B.; Choo, Yung K.; Schilling, Herbert W.; Baez, Marivell; Braun, Donald C.; Cotton, Barbara J.
2001-01-01
Two-dimensional CID analysis for iced airfoils can be a labor-intensive task. The software toolkit SmaggIce 2D is being developed to help streamline the CID process and provide the unique features needed for icing. When complete, it will include a combination of partially automated and fully interactive tools for all aspects of the tasks leading up to the flow analysis: geometry preparation, domain decomposition. block boundary demoralization. gridding, and linking with a flow solver. It also includes tools to perform ice shape characterization, an important aid in determining the relationship between ice characteristics and their effects on aerodynamic performance. Completed tools, work-in-progress, and planned features of the software toolkit are presented here.
An Integrative Model of Excitation Driven Fluid Flow in a 2D Uterine Channel
NASA Astrophysics Data System (ADS)
Maggio, Charles; Fauci, Lisa; Chrispell, John
2009-11-01
We present a model of intra-uterine fluid flow in a sagittal cross-section of the uterus by inducing peristalsis in a 2D channel. This is an integrative multiscale computational model that takes as input fluid viscosity, passive tissue properties of the uterine channel and a prescribed wave of membrane depolarization. This voltage pulse is coupled to a model of calcium dynamics inside a uterine smooth muscle cell, which in turn drives a kinetic model of myosin phosphorylation governing contractile muscle forces. Using the immersed boundary method, these muscle forces are communicated to a fluid domain to simulate the contractions which occur in a human uterus. An analysis of the effects of model parameters on the flow properties and emergent geometry of the peristaltic channel will be presented.
Study of the mechanical behavior of a 2-D carbon-carbon composite
NASA Technical Reports Server (NTRS)
Avery, W. B.; Herakovich, C. T.
1987-01-01
The out-of-plane fracture of a 2-D carbon-carbon composite was observed and characterized to gain an understanding of the factors influencing the stress distribution in such a laminate. Finite element analyses of a two-ply carbon-carbon composite under in-plane, out-of-plane, and thermal loading were performed. Under in-plane loading all components of stress were strong functions of geometry. Additionally, large thermal stresses were predicted. Out-of-plane tensile tests revealed that failure was interlaminar, and that cracks propagated along the fiber-matrix interface. An elasticity solution was utilized to analyze an orthotropic fiber in an isotropic matrix under uniform thermal load. The analysis reveals that the stress distributions in a transversely orthotropic fiber are radically different than those predicted assuming the fiber to be transversely isotropic.
2D full wave modeling for a synthetic Doppler backscattering diagnostic
Hillesheim, J. C.; Schmitz, L.; Kubota, S.; Rhodes, T. L.; Carter, T. A.; Holland, C.
2012-10-15
Doppler backscattering (DBS) is a plasma diagnostic used in tokamaks and other magnetic confinement devices to measure the fluctuation level of intermediate wavenumber (k{sub {theta}}{rho}{sub s}{approx} 1) density fluctuations and the lab frame propagation velocity of turbulence. Here, a synthetic DBS diagnostic is described, which has been used for comparisons between measurements in the DIII-D tokamak and predictions from nonlinear gyrokinetic simulations. To estimate the wavenumber range to which a Gaussian beam would be sensitive, a ray tracing code and a 2D finite difference, time domain full wave code are used. Experimental density profiles and magnetic geometry are used along with the experimental antenna and beam characteristics. An example of the effect of the synthetic diagnostic on the output of a nonlinear gyrokinetic simulation is presented.
2D full wave modeling for a synthetic Doppler backscattering diagnostic.
Hillesheim, J C; Holland, C; Schmitz, L; Kubota, S; Rhodes, T L; Carter, T A
2012-10-01
Doppler backscattering (DBS) is a plasma diagnostic used in tokamaks and other magnetic confinement devices to measure the fluctuation level of intermediate wavenumber (k(?)?(s) ~ 1) density fluctuations and the lab frame propagation velocity of turbulence. Here, a synthetic DBS diagnostic is described, which has been used for comparisons between measurements in the DIII-D tokamak and predictions from nonlinear gyrokinetic simulations. To estimate the wavenumber range to which a Gaussian beam would be sensitive, a ray tracing code and a 2D finite difference, time domain full wave code are used. Experimental density profiles and magnetic geometry are used along with the experimental antenna and beam characteristics. An example of the effect of the synthetic diagnostic on the output of a nonlinear gyrokinetic simulation is presented. PMID:23126989
Genetics, genomics, and evolutionary biology of NKG2D ligands.
Carapito, Raphael; Bahram, Seiamak
2015-09-01
Human and mouse NKG2D ligands (NKG2DLs) are absent or only poorly expressed by most normal cells but are upregulated by cell stress, hence, alerting the immune system in case of malignancy or infection. Although these ligands are numerous and highly variable (at genetic, genomic, structural, and biochemical levels), they all belong to the major histocompatibility complex class I gene superfamily and bind to a single, invariant, receptor: NKG2D. NKG2D (CD314) is an activating receptor expressed on NK cells and subsets of T cells that have a key role in the recognition and lysis of infected and tumor cells. Here, we review the molecular diversity of NKG2DLs, discuss the increasing appreciation of their roles in a variety of medical conditions, and propose several explanations for the evolutionary force(s) that seem to drive the multiplicity and diversity of NKG2DLs while maintaining their interaction with a single invariant receptor. PMID:26284473
Graphene based 2D-materials for supercapacitors
NASA Astrophysics Data System (ADS)
Palaniselvam, Thangavelu; Baek, Jong-Beom
2015-09-01
Ever-increasing energy demands and the depletion of fossil fuels are compelling humanity toward the development of suitable electrochemical energy conversion and storage devices to attain a more sustainable society with adequate renewable energy and zero environmental pollution. In this regard, supercapacitors are being contemplated as potential energy storage devices to afford cleaner, environmentally friendly energy. Recently, a great deal of attention has been paid to two-dimensional (2D) nanomaterials, including 2D graphene and its inorganic analogues (transition metal double layer hydroxides, chalcogenides, etc), as potential electrodes for the development of supercapacitors with high electrochemical performance. This review provides an overview of the recent progress in using these graphene-based 2D materials as potential electrodes for supercapacitors. In addition, future research trends including notable challenges and opportunities are also discussed.
2D growth processes: SLE and Loewner chains
Michel Bauer; Denis Bernard
2006-02-20
This review provides an introduction to two dimensional growth processes. Although it covers a variety processes such as diffusion limited aggregation, it is mostly devoted to a detailed presentation of stochastic Schramm-Loewner evolutions (SLE) which are Markov processes describing interfaces in 2D critical systems. It starts with an informal discussion, using numerical simulations, of various examples of 2D growth processes and their connections with statistical mechanics. SLE is then introduced and Schramm's argument mapping conformally invariant interfaces to SLE is explained. A substantial part of the review is devoted to reveal the deep connections between statistical mechanics and processes, and more specifically to the present context, between 2D critical systems and SLE. Some of the SLE remarkable properties are explained, as well as the tools for computing with SLE. This review has been written with the aim of filling the gap between the mathematical and the physical literatures on the subject.
Simultaneous 2D Strain Sensing Using Polymer Planar Bragg Gratings
Rosenberger, Manuel; Eisenbeil, Waltraud; Schmauss, Bernhard; Hellmann, Ralf
2015-01-01
We demonstrate the application of polymer planar Bragg gratings for multi-axial strain sensing and particularly highlight simultaneous 2D strain measurement. A polymer planar Bragg grating (PPBG) fabricated with a single writing step in bulk polymethylmethacrylate is used for measuring both tensile and compressive strain at various angles. It is shown that the sensitivity of the PPBG strongly depends on the angle between the optical waveguide into which the grating is inscribed and the direction along which the mechanical load is applied. Additionally, a 2D PPBG fabricated by writing two Bragg gratings angularly displaced from each other into a single polymer platelet is bonded to a stainless steel plate. The two reflected wavelengths exhibit different sensitivities while tested toward tensile and compressive strain. These characteristics make 2D PPBG suitable for measuring multi-axial tensile and compressive strain. PMID:25686313
Geometrie im Internet Wolfgang Rath
Havlicek, Hans
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
Induced geometry from disformal transformation
Fang-Fang Yuan; Peng Huang
2015-02-08
In this note, we use the disformal transformation to induce a geometry from the manifold which is originally Riemannian. The new geometry obtained here can be considered as a generalization of Weyl integrable geometry. Based on these results, we further propose a geometry which is naturally a generalization of Weyl geometry.
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
NASA Astrophysics Data System (ADS)
Tønning, Erik; Polders, Daniel; Callaghan, Paul T.; Engelsen, Søren B.
2007-09-01
This paper demonstrates how the multi-linear PARAFAC model can with advantage be used to decompose 2D diffusion-relaxation correlation NMR spectra prior to 2D-Laplace inversion to the T2- D domain. The decomposition is advantageous for better interpretation of the complex correlation maps as well as for the quantification of extracted T2- D components. To demonstrate the new method seventeen mixtures of wheat flour, starch, gluten, oil and water were prepared and measured with a 300 MHz nuclear magnetic resonance (NMR) spectrometer using a pulsed gradient stimulated echo (PGSTE) pulse sequence followed by a Carr-Purcell-Meiboom-Gill (CPMG) pulse echo train. By varying the gradient strength, 2D diffusion-relaxation data were recorded for each sample. From these double exponentially decaying relaxation data the PARAFAC algorithm extracted two unique diffusion-relaxation components, explaining 99.8% of the variation in the data set. These two components were subsequently transformed to the T2- D domain using 2D-inverse Laplace transformation and quantitatively assigned to the oil and water components of the samples. The oil component was one distinct distribution with peak intensity at D = 3 × 10 -12 m 2 s -1 and T2 = 180 ms. The water component consisted of two broad populations of water molecules with diffusion coefficients and relaxation times centered around correlation pairs: D = 10 -9 m 2 s -1, T2 = 10 ms and D = 3 × 10 -13 m 2 s -1, T2 = 13 ms. Small spurious peaks observed in the inverse Laplace transformation of original complex data were effectively filtered by the PARAFAC decomposition and thus considered artefacts from the complex Laplace transformation. The oil-to-water ratio determined by PARAFAC followed by 2D-Laplace inversion was perfectly correlated with known oil-to-water ratio of the samples. The new method of using PARAFAC prior to the 2D-Laplace inversion proved to have superior potential in analysis of diffusion-relaxation spectra, as it improves not only the interpretation, but also the quantification.
Radiative heat transfer in 2D Dirac materials
Pablo Rodriguez-Lopez; Wang-Kong Tse; Diego A. R. Dalvit
2015-07-29
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.
On 2D bisection method for double eigenvalue problems
Ji, X.
1996-06-01
The two-dimensional bisection method presented in (SIAM J. Matrix Anal. Appl. 13(4), 1085 (1992)) is efficient for solving a class of double eigenvalue problems. This paper further extends the 2D bisection method of full matrix cases and analyses its stability. As in a single parameter case, the 2D bisection method is very stable for the tridiagonal matrix triples satisfying the symmetric-definite condition. Since the double eigenvalue problems arise from two-parameter boundary value problems, an estimate of the discretization error in eigenpairs is also given. Some numerical examples are included. 42 refs., 1 tab.
Integrability from 2d {N}=(2,2) dualities
NASA Astrophysics Data System (ADS)
Yamazaki, Masahito; Yan, Wenbin
2015-10-01
We study integrable models in the context of the recently discovered Gauge/YBE correspondence, where the Yang-Baxter equation (YBE) is promoted to a duality between two supersymmetric gauge theories. We study flavored elliptic genus of 2d {N}=(2,2) quiver gauge theories, which are defined from statistical lattices regarded as quiver diagrams. Our R-matrices are written in terms of theta functions and simplify considerably when the gauge groups at the quiver nodes are Abelian. We also discuss the modularity properties of the R-matrix, reduction of 2d index to 1d Witten index, and string theory realizations of our theories.
Using 2-D arrays for sensing multimodal Lamb waves
NASA Astrophysics Data System (ADS)
Engholm, Marcus; Stepinski, Tadeusz
2010-04-01
Monitoring structural integrity of large planar structures requires normally a relatively dense network of uniformly distributed ultrasonic sensors. A 2-D ultrasonic phased array with all azimuth angle coverage would be extremely useful for the structural health monitoring (SHM) of such structures. Known techniques for estimating direction of arriving (DOA) waves cannot efficiently cope with dispersive and multimodal Lamb waves (LWs). In the paper we propose an adaptive spectral estimation technique capable of handling broadband LWs sensed by 2-D arrays, the modified Capon method. Performance of the technique is evaluated using simulated multiple-mode LWs, and verified using experimental data.
Codeine intoxication associated with ultrarapid CYP2D6 metabolism.
Gasche, Yvan; Daali, Youssef; Fathi, Marc; Chiappe, Alberto; Cottini, Silvia; Dayer, Pierre; Desmeules, Jules
2004-12-30
Life-threatening opioid intoxication developed in a patient after he was given small doses of codeine for the treatment of a cough associated with bilateral pneumonia. Codeine is bioactivated by CYP2D6 into morphine, which then undergoes further glucuronidation. CYP2D6 genotyping showed that the patient had three or more functional alleles, a finding consistent with ultrarapid metabolism of codeine. We attribute the toxicity to this genotype, in combination with inhibition of CYP3A4 activity by other medications and a transient reduction in renal function. PMID:15625333
Design of the LRP airfoil series using 2D CFD
NASA Astrophysics Data System (ADS)
Zahle, Frederik; Bak, Christian; Sørensen, 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.
Quantum process tomography by 2D fluorescence spectroscopy
Pachón, Leonardo A.; Marcus, Andrew H.; Aspuru-Guzik, Alán
2015-06-07
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.
Experimental validation of equations for 2D DIC uncertainty quantification.
Reu, Phillip L.; Miller, Timothy J.
2010-03-01
Uncertainty quantification (UQ) equations have been derived for predicting matching uncertainty in two-dimensional image correlation a priori. These equations include terms that represent the image noise and image contrast. Researchers at the University of South Carolina have extended previous 1D work to calculate matching errors in 2D. These 2D equations have been coded into a Sandia National Laboratories UQ software package to predict the uncertainty for DIC images. This paper presents those equations and the resulting error surfaces for trial speckle images. Comparison of the UQ results with experimentally subpixel-shifted images is also discussed.
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.
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.
Radiative heat transfer in 2D Dirac materials
Rodriguez-López, Pablo; Tse, Wang -Kong; Dalvit, Diego A. R.
2015-05-12
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. In conclusion, we discuss the limitations to the validity of this scaling law imposed by spatial dispersion in 2D Dirac materials.
Examination of Measurement Apparatus for 2-D Magnetic Properties
NASA Astrophysics Data System (ADS)
Maeda, Yoshitaka; Urata, Shinya; Kano, Yuko; Arakawa, Toshinobu; Yanase, Shunji; Okazaki, Yasuo; Watanabe, Shota
Development of high efficient electrical rotating machines is an important issue in energy conservation. To realize this purpose, we have to consider details of magnetic phenomena in rotating machines. Therefore an accurate evaluation of the 2-D magnetic properties is indispensable. However, it is very difficult to measure these properties especially under high magnetic induction due to difficulty to measure rotating magnetic properties in the electrical steel sheets. In this paper, a new apparatus with 8-teeth-core, distributed windings, and inter-poles is proposed to measure the 2-D magnetic properties. We evaluate the uniformity of magnetic conditions in the specimen by using the finite element analysis.
Dynamics of 2D Dust Clusters with a Perpendicular Magnetic Field
NASA Astrophysics Data System (ADS)
Greiner, Franko; Carstensen, Jan; Hou, Lu-Jing; Piel, Alexander
2008-09-01
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 (?40 ?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.
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.
Magnetic properties of 2D nickel nanostrips: structure dependent magnetism and Stoner criterion.
Kashid, Vikas; Shah, Vaishali; Salunke, H G; Mokrousov, Yuriy; Blügel, Stefan
2015-08-12
We have investigated different geometries of two-dimensional (2D) infinite length Ni nanowires of increasing width using spin density functional theory calculations. Our simulations demonstrate that the parallelogram motif is the most stable and structures that incorporate the parallelogram motif are more stable as compared to rectangular structures. The wires are conducting and the conductance channels increase with increasing width. The wires have a non-linear behavior in the ballistic anisotropic magnetoresistance ratios (BAMR) with respect to the magnetization directions. All 2D nanowires as well as Ni (1 1 1) and Ni (1 0 0) monolayer investigated are ferromagnetic under the Stoner criterion and exhibit enhanced magnetic moments as compared to bulk Ni and the respective Ni monolayers. The easy axis for all nickel nanowires under investigation is observed to be along the wire axis. The double rectangular nanowire exhibits a magnetic anomaly with a smaller magnetic moment when compared to Ni (1 0 0) monolayer and is the only structure with an easy axis perpendicular to the wire axis. The Stoner parameter which has been known to be structure independent in bulk and surfaces is found to vary with the structure and the width of the nanowires. The less stable rectangular and rhombus shaped nanowires have a higher ferromagnetic strength than parallelogram shaped nanowires. PMID:26189771
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
Dynamics of 2D Dust Clusters with a Perpendicular Magnetic Field
Greiner, Franko; Carstensen, Jan; Hou Lujing; Piel, Alexander
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)
Ray, Anandaroop; Key, Kerry; Bodin, Thomas; Myer, David; Constable, Steven
2014-12-01
We apply a reversible-jump Markov chain Monte Carlo method to sample the Bayesian posterior model probability density function of 2-D seafloor resistivity as constrained by marine controlled source electromagnetic data. This density function of earth models conveys information on which parts of the model space are illuminated by the data. Whereas conventional gradient-based inversion approaches require subjective regularization choices to stabilize this highly non-linear and non-unique inverse problem and provide only a single solution with no model uncertainty information, the method we use entirely avoids model regularization. The result of our approach is an ensemble of models that can be visualized and queried to provide meaningful information about the sensitivity of the data to the subsurface, and the level of resolution of model parameters. We represent models in 2-D using a Voronoi cell parametrization. To make the 2-D problem practical, we use a source-receiver common midpoint approximation with 1-D forward modelling. Our algorithm is transdimensional and self-parametrizing where the number of resistivity cells within a 2-D depth section is variable, as are their positions and geometries. Two synthetic studies demonstrate the algorithm's use in the appraisal of a thin, segmented, resistive reservoir which makes for a challenging exploration target. As a demonstration example, we apply our method to survey data collected over the Scarborough gas field on the Northwest Australian shelf.
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.
Computation of neutron fluxes in clusters of fuel pins arranged in hexagonal assemblies (2D and 3D)
Prabha, H.; Marleau, G.
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.
Patterned Arrays of Lateral Heterojunctions within Monolayer 2D Semiconductors
Mahjouri-Samani, Masoud; Lin, Ming-Wei; Wang, Kai; Lupini, Andrew R; Lee, Jaekwang; Basile Carrasco, Leonardo A; Rouleau, Christopher M; Boulesbaa, Abdelaziz; Puretzky, Alexander A; Ivanov, Ilia N; et al
2015-01-01
The formation of semiconductor heterojunctions and their high density integration are foundations of modern electronics and optoelectronics. To enable two-dimensional (2D) crystalline semiconductors as building blocks in next generation electronics, developing methods to deterministically form lateral heterojunctions is crucial. Here we demonstrate a process strategy for the formation of lithographically-patterned lateral semiconducting heterojunctions within a single 2D crystal. E-beam lithography is used to pattern MoSe2 monolayer crystals with SiO2, and the exposed locations are selectively and totally converted to MoS2 using pulsed laser deposition (PLD) of sulfur in order to form MoSe2/MoS2 heterojunctions in predefined patterns. The junctions and conversionmore »process are characterized by atomically resolved scanning transmission electron microscopy, photoluminescence, and Raman spectroscopy. This demonstration of lateral semiconductor heterojunction arrays within a single 2D crystal is an essential step for the lateral integration of 2D semiconductor building blocks with different electronic and optoelectronic properties for high-density, ultrathin circuitry.« less
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...
RADMC: A 2-D Continuum Radiative Transfer Tool
NASA Astrophysics Data System (ADS)
Dullemond, C. P.
2011-08-01
RADMC is a 2-D Monte-Carlo code for dust continuum radiative transfer circumstellar disks and envelopes. It is based on the method of Bjorkman & Wood (ApJ 2001, 554, 615), but with several modifications to produce smoother results with fewer photon packages.
Proteomic profiling of macrophages by 2D electrophoresis.
Bouvet, Marion; Turkieh, Annie; Acosta-Martin, Adelina E; Chwastyniak, Maggy; Beseme, Olivia; Amouyel, Philippe; Pinet, Florence
2014-01-01
The goal of the two-dimensional (2D) electrophoresis protocol described here is to show how to analyse the phenotype of human cultured macrophages. The key role of macrophages has been shown in various pathological disorders such as inflammatory, immunological, and infectious diseases. In this protocol, we use primary cultures of human monocyte-derived macrophages that can be differentiated into the M1 (pro-inflammatory) or the M2 (anti-inflammatory) phenotype. This in vitro model is reliable for studying the biological activities of M1 and M2 macrophages and also for a proteomic approach. Proteomic techniques are useful for comparing the phenotype and behaviour of M1 and M2 macrophages during host pathogenicity. 2D gel electrophoresis is a powerful proteomic technique for mapping large numbers of proteins or polypeptides simultaneously. We describe the protocol of 2D electrophoresis using fluorescent dyes, named 2D Differential Gel Electrophoresis (DIGE). The M1 and M2 macrophages proteins are labelled with cyanine dyes before separation by isoelectric focusing, according to their isoelectric point in the first dimension, and their molecular mass, in the second dimension. Separated protein or polypeptidic spots are then used to detect differences in protein or polypeptide expression levels. The proteomic approaches described here allows the investigation of the macrophage protein changes associated with various disorders like host pathogenicity or microbial toxins. PMID:25408153
Syndrome identification based on 2D analysis Stefan Boehringer*,1
Würtz, Rolf P.
2D pictures of patients each being affected with one of 10 syndromes (fragile X syndrome; Cornelia and the evaluation of the overall impression of a patient by the examiner. Imprecise and nonstandardized nomenclature. Other more subtle problems involve the very process of perception, which is subject to influence from
2D SNS junction with Rashba spin-orbit interaction
Fominov, Yakov
2D SNS junction with Rashba spin-orbit interaction Ol'ga V. Dimitrova and M. V. Feigel'man #12 of the total Josephson current on the spin-orbit coupling, derived for the general case of an arbitrary length of the Beenakker's formula for Andreev levels in presence of Rashba spin-orbit interaction #12;The role of boundary
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...
Patterned Arrays of Lateral Heterojunctions within Monolayer 2D Semiconductors
Mahjouri-Samani, Masoud; Lin, Ming-Wei; Wang, Kai; Lupini, Andrew R; Lee, Jaekwang; Basile Carrasco, Leonardo A; Rouleau, Christopher M; Boulesbaa, Abdelaziz; Puretzky, Alexander A; Ivanov, Ilia N; Xiao, Kai; Yoon, Mina; Geohegan, David B
2015-01-01
The formation of semiconductor heterojunctions and their high density integration are foundations of modern electronics and optoelectronics. To enable two-dimensional (2D) crystalline semiconductors as building blocks in next generation electronics, developing methods to deterministically form lateral heterojunctions is crucial. Here we demonstrate a process strategy for the formation of lithographically-patterned lateral semiconducting heterojunctions within a single 2D crystal. E-beam lithography is used to pattern MoSe2 monolayer crystals with SiO2, and the exposed locations are selectively and totally converted to MoS2 using pulsed laser deposition (PLD) of sulfur in order to form MoSe2/MoS2 heterojunctions in predefined patterns. The junctions and conversion process are characterized by atomically resolved scanning transmission electron microscopy, photoluminescence, and Raman spectroscopy. This demonstration of lateral semiconductor heterojunction arrays within a single 2D crystal is an essential step for the lateral integration of 2D semiconductor building blocks with different electronic and optoelectronic properties for high-density, ultrathin circuitry.
Creation of a scalar potential in 2D dilaton gravity
Behrndt, K.
1994-09-01
The authors investigate quantum corrections of the 2-d dilaton gravity near the singularity. Their motivation comes from a s-wave reduced cosmological solution which is classically singular in the scalar fields (dilaton and moduli). As a result they find, that the singularity disappears and a dilaton/moduli potential is created.
Procter & Gamble Co. 379 F.2d 675
Shamos, Michael I.
Morrissey v. Procter & Gamble Co. 379 F.2d 675 United States Court of Appeals, First Circuit June, Procter & Gamble Company, infringed, by copying, almost precisely, Rule 1. In its motion for summary of 2Morrissey v. Proctor & Gamble Co. 9/26/2007http
2D signature for detection and identification of drugs
NASA Astrophysics Data System (ADS)
Trofimov, Vyacheslav A.; Varentsova, Svetlana A.; Shen, Jingling; Zhang, Cunlin; Zhou, Qingli; Shi, Yulei
2011-06-01
The method of spectral dynamics analysis (SDA-method) is used for obtaining the2D THz signature of drugs. This signature is used for the detection and identification of drugs with similar Fourier spectra by transmitted THz signal. We discuss the efficiency of SDA method for the identification problem of pure methamphetamine (MA), methylenedioxyamphetamine (MDA), 3, 4-methylenedioxymethamphetamine (MDMA) and Ketamine.
2D and 3D Elasticity Imaging Using Freehand Ultrasound
Drummond, Tom
2D and 3D Elasticity Imaging Using Freehand Ultrasound Joel Edward Lindop Pembroke College March property (e.g., density). Various new scanning techniques are aimed at producing elasticity images related for almost two decades. Elasticity images are produced by estimating and analysing quasistatic deformations
Detection of N$_2$D$^+$ in a protoplanetary disk
Huang, Jane
2015-01-01
Observations of deuterium fractionation in the solar system, and in interstellar and circumstellar material, are commonly used to constrain the formation environment of volatiles. Toward protoplanetary disks, this approach has been limited by the small number of detected deuterated molecules, i.e. DCO$^+$ and DCN. Based on ALMA Cycle 2 observations toward the disk around the T Tauri star AS 209, we report the first detection of N$_2$D$^+$ (J=3-2) in a protoplanetary disk. These data are used together with previous Submillimeter Array observations of N$_2$H$^+$ (J=3-2) to estimate a disk-averaged D/H ratio of 0.3--0.5, an order of magnitude higher than disk-averaged ratios previously derived for DCN/HCN and DCO$^+$/HCO$^+$ around other young stars. The high fractionation in N$_2$H$^+$ is consistent with model predictions. The presence of abundant N$_2$D$^+$ toward AS 209 also suggests that N$_2$D$^+$ and the N$_2$D$^+$/N$_2$H$^+$ ratio can be developed into effective probes of deuterium chemistry, kinematics, ...
ELLIPT2D: A Flexible Finite Element Code Written Python
Pletzer, A.; Mollis, J.C.
2001-03-22
The use of the Python scripting language for scientific applications and in particular to solve partial differential equations is explored. It is shown that Python's rich data structure and object-oriented features can be exploited to write programs that are not only significantly more concise than their counter parts written in Fortran, C or C++, but are also numerically efficient. To illustrate this, a two-dimensional finite element code (ELLIPT2D) has been written. ELLIPT2D provides a flexible and easy-to-use framework for solving a large class of second-order elliptic problems. The program allows for structured or unstructured meshes. All functions defining the elliptic operator are user supplied and so are the boundary conditions, which can be of Dirichlet, Neumann or Robbins type. ELLIPT2D makes extensive use of dictionaries (hash tables) as a way to represent sparse matrices.Other key features of the Python language that have been widely used include: operator over loading, error handling, array slicing, and the Tkinter module for building graphical use interfaces. As an example of the utility of ELLIPT2D, a nonlinear solution of the Grad-Shafranov equation is computed using a Newton iterative scheme. A second application focuses on a solution of the toroidal Laplace equation coupled to a magnetohydrodynamic stability code, a problem arising in the context of magnetic fusion research.
Dislocation Structures in Disordered 2D Vortex Matter
Dislocation Structures in Disordered 2D Vortex Matter M. Chandran, R. Scalettar & G.T. Zimanyi U/Low Fields: quasi Bragg Glass (qBG) (Giamarchi, Le Doussal): Dislocations extremely widely separated Disorder): Dislocations dense Only crossover, not true phase transition #12;Picture of quasi Bragg Glass Dislocations are
2D superconductivity in single crystals of LSCO
Keren, Amit
/h), rotation of the feed rod and crystal ·Growing atmosphere It appears that LSCO grows with it's c2D superconductivity in single crystals of LSCO DrachuckGil Amit Keren Colaborators: Galina this unintentionally while measuring magnetization of single crystal of LSCO with different orientations. #12;Traveling
Validation and testing of the VAM2D computer code
Kool, J.B.; Wu, Y.S. )
1991-10-01
This document describes two modeling studies conducted by HydroGeoLogic, Inc. for the US NRC under contract no. NRC-04089-090, entitled, Validation and Testing of the VAM2D Computer Code.'' VAM2D is a two-dimensional, variably saturated flow and transport code, with applications for performance assessment of nuclear waste disposal. The computer code itself is documented in a separate NUREG document (NUREG/CR-5352, 1989). The studies presented in this report involve application of the VAM2D code to two diverse subsurface modeling problems. The first one involves modeling of infiltration and redistribution of water and solutes in an initially dry, heterogeneous field soil. This application involves detailed modeling over a relatively short, 9-month time period. The second problem pertains to the application of VAM2D to the modeling of a waste disposal facility in a fractured clay, over much larger space and time scales and with particular emphasis on the applicability and reliability of using equivalent porous medium approach for simulating flow and transport in fractured geologic media. Reflecting the separate and distinct nature of the two problems studied, this report is organized in two separate parts. 61 refs., 31 figs., 9 tabs.
2-D Imaging of Electron Temperature in Tokamak Plasmas
T. Munsat; E. Mazzucato; H. Park; C.W. Domier; M. Johnson; N.C. Luhmann Jr.; J. Wang; Z. Xia; I.G.J. Classen; A.J.H. Donne; M.J. van de Pol
2004-07-08
By taking advantage of recent developments in millimeter wave imaging technology, an Electron Cyclotron Emission Imaging (ECEI) instrument, capable of simultaneously measuring 128 channels of localized electron temperature over a 2-D map in the poloidal plane, has been developed for the TEXTOR tokamak. Data from the new instrument, detailing the MHD activity associated with a sawtooth crash, is presented.
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…
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 Topographical Maps to 3D Models. Rob Gillespie Consultant Visualization, Media and Imaging Laboratory jrgilles@itg.uiuc.edu Figure 1: left: red blood cells imaged on AFM (J. Gunther), right: The resulting 3D model produced using
Communication Arrayed acquisition of 2D exchange NMR spectra within
Frydman, Lucio
Communication Arrayed acquisition of 2D exchange NMR spectra within a single scan experiment Boaz of a series of time-incremented spectra. The present Communication exemplifies this concept by showing how, this strategy found its most widespread application in the characterization of co- herent forms of spin
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 to 3D Models. Rob Gillespie Consultant Visualization, Media and Imaging Laboratory jrgilles of the image you are going to change into a 3D model. If nothing is entered in the next field it is also
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.
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
ERIC Educational Resources Information Center
Chern, Shiing-Shen
1990-01-01
Discussed are the major historical developments of geometry. Euclid, Descartes, Klein's Erlanger Program, Gaus and Riemann, globalization, topology, Elie Cartan, and an application to molecular biology are included as topics. (KR)
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)
Noncommutative Geometry and Physics
Connes, Alain
2006-11-03
In this very short essay we shall describe a 'spectral' point of view on geometry which allows to start taking into account the lessons from both renormalization and of general relativity. We shall first do that for renormalization and explain in rough outline the content of our recent collaborations with Dirk Kreimer and Matilde Marcolli leading to the universal Galois symmetry of renormalizable quantum field theories provided by the renormalization group in its cosmic Galois group incarnation. As far as general relativity is concerned, since the functional integral cannot be treated in the traditional perturbative manner, it relies heavily as a 'sum over geometries' on the chosen paradigm of geometric space. This will give us the occasion to discuss, in the light of noncommutative geometry, the issue of 'observables' in gravity and our joint work with Ali Chamseddine on the spectral action, with a first attempt to write down a functional integral on the space of noncommutative geometries.
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)
Cytochrome P450-2D6 Screening Among Elderly Using Antidepressants (CYSCE)
2015-12-09
Depression; Depressive Disorder; Poor Metabolizer Due to Cytochrome P450 CYP2D6 Variant; Intermediate Metabolizer Due to Cytochrome P450 CYP2D6 Variant; Ultrarapid Metabolizer Due to Cytochrome P450 CYP2D6 Variant
A community benchmark for viscoplastic thermal convection in a 2-D square box
NASA Astrophysics Data System (ADS)
Tosi, N.; Stein, C.; Noack, L.; Hüttig, C.; Maierová, P.; Samuel, H.; Davies, D. R.; Wilson, C. R.; Kramer, S. C.; Thieulot, C.; Glerum, A.; Fraters, M.; Spakman, W.; Rozel, A.; Tackley, P. J.
2015-07-01
Numerical simulations of thermal convection in the Earth's mantle often employ a pseudoplastic 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. Here we present a suite of simple tests based on nonlinear rheologies featuring temperature, pressure, and strain rate-dependent viscosity. Eleven different codes based on the finite volume, finite element, or spectral methods have been used to run five benchmark cases leading to stagnant lid, mobile lid, and periodic convection in a 2-D square 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 a mobile lid regime to a periodic regime, and from a periodic regime to a stagnant lid regime, as a function of the yield stress. At a 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 nonlinear rheologies. Furthermore, they consistently predict the critical value of the yield stress at which the transition between different regimes occurs. As the most recent mantle convection codes can handle a number of different geometries within a single solution framework, this benchmark will also prove useful when validating viscoplastic thermal convection simulations in such geometries.
NASA Astrophysics Data System (ADS)
Ceresole, Anna; Ferrara, Sergio; Gnecchi, Alessandra; Marrani, Alessio
2013-02-01
We analyze some properties of the four dimensional supergravity theories which originate from five dimensions upon reduction. They generalize to N > 2 extended supersymmetries the d-geometries with cubic prepotentials, familiar from N = 2 special Kähler geometry. We emphasize the role of a suitable parametrization of the scalar fields and the corresponding triangular symplectic basis. We also consider applications to the first order flow equations for non-BPS extremal black holes.
Energy Science and Technology Software Center (ESTSC)
2005-01-01
The Common Geometry Module (CGM) is a code library which provides geometry functionality used for mesh generation and other applications. This functionality includes that commonly found in solid modeling engines, like geometry creation, query and modification; CGM also includes capabilities not commonly found in solid modeling engines, like geometry decomposition tools and support for shared material interfaces. CGM is built upon the ACIS solid modeling engine, but also includes geometry capability developed beside and onmore »top of ACIS. CGM can be used as-is to provide geometry functionality for codes needing this capability. However, CGM can also be extended using derived classes in C++, allowing the geometric model to serve as the basis for other applications, for example mesh generation. CGM is supported on Sun Solaris, SGI, HP, IBM, DEC, Linux and Windows NT platforms. CGM also indudes support for loading ACIS models on parallel computers, using MPI-based communication. Future plans for CGM are to port it to different solid modeling engines, including Pro/Engineer or SolidWorks. CGM is being released into the public domain under an LGPL license; the ACIS-based engine is available to ACIS licensees on request.« less
Kraloua, B.; Hennad, A.
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.
Investigations of flowfields found in typical combustor geometries
NASA Technical Reports Server (NTRS)
Lilley, D. G.
1982-01-01
Experimental and theoretical research undertaken on 2-D axisymmetric geometries under low speed, nonreacting, turbulent, swirling flow conditions is reported. The flow enters the test section and proceeds into a larger chamber (the expansion ratio D/d = 2) via a sudden or gradual expansion (sidewall angle alpha = 90 and 45 degrees). Inlet swirl vanes are adjustable to a variety of vane angles with values of phi = 0, 38, 45, 60 and 70 degrees being emphasized.
NASA Astrophysics Data System (ADS)
Kiflu, H. G.; Kruse, S. E.; Harro, D.; Loke, M. H.; Wilkinson, P. B.
2013-12-01
Electrical resistivity tomography is commonly used to identify geologic features associated with sinkhole formation. In covered karst terrain, however, it can be difficult to resolve the depth to top of limestone with this method. This is due to the fact that array lengths, and hence depth of resolution, are often limited by residential or commercial lot dimensions in urban environments. Furthermore, the sediments mantling the limestone are often clay-rich and highly conductive. The resistivity method has limited sensitivity to resistive zones beneath conductive zones. This sensitivity can be improved significantly with electrodes implanted at depth in the cover sediments near the top of limestone. An array of deep electrodes is installed with direct push technology in the karst cover. When combined with a surface array in which each surface electrode is underlain by a deep electrode, the array geometry is similar to a borehole array turned on its side. This method, called the Multi-Electrode Resistivity Implant Technique (MERIT), offers the promise of significantly improved resolution of epikarst and cover collapse development zones in the overlying sediment, the limestone or at the sediment-bedrock interface in heterogeneous karst environments. With a non-traditional array design, the question of optimal array geometries arises. Optimizing array geometries is complicated by the fact that many plausible 4-electrode readings will produce negative apparent resistivity values, even in homogeneous terrain. Negative apparent resistivities cannot be used in inversions based on the logarithm of the apparent resistivity. New algorithms for seeking optimal array geometries have been developed by modifying the 'Compare R' method of Wilkinson and Loke. The optimized arrays show significantly improved resolution over basic arrays adapted from traditional 2D surface geometries. Several MERIT case study surveys have been conducted in covered karst in west-central Florida, with 28-electrode arrays with electrodes 2-5 meters apart, and the deep arrays buried at 4-8 meters depth. Ground penetrating radar surveys, SPT borings and coring data provide selected 'ground truthing'. The case studies show that inclusion of the deep electrode array permits karst features such as undulations at the top of limestone and raveling zones within surficial sediments to be imaged. These features are not accessible from surface arrays with equivalent surface footprints. The method also has better resolution at depth at the ends of the lines, where surface arrays are typically plotted with a trapezoidal truncation due to poor resolution at the lower corners of the profile.
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
Modeling seismic wave propagation and amplification in 1D/2D/3D linear and nonlinear unbounded media
Semblat, Jean-François
2011-01-01
To analyze seismic wave propagation in geological structures, it is possible to consider various numerical approaches: the finite difference method, the spectral element method, the boundary element method, the finite element method, the finite volume method, etc. All these methods have various advantages and drawbacks. The amplification of seismic waves in surface soil layers is mainly due to the velocity contrast between these layers and, possibly, to topographic effects around crests and hills. The influence of the geometry of alluvial basins on the amplification process is also know to be large. Nevertheless, strong heterogeneities and complex geometries are not easy to take into account with all numerical methods. 2D/3D models are needed in many situations and the efficiency/accuracy of the numerical methods in such cases is in question. Furthermore, the radiation conditions at infinity are not easy to handle with finite differences or finite/spectral elements whereas it is explicitely accounted in the B...
The Geometry Of War The Geometry Of War
Aslaksen, Helmer
The Geometry Of War 1 #12;The Geometry Of War GEM1518K Mathematics in Arts &Architecture Presenting : The Geometry Of War Prepared by: 1) Linda Tjoe Matriculation number: U017984E 2) Lince Salim Matriculation017997 2 #12;The Geometry Of War Contents Page(s) Introduction 1 1.1 Early Canon 2 1.2 The Triumph
2-D linear motion system. Innovative technology summary report
1998-11-01
The US Department of Energy's (DOE's) nuclear facility decontamination and decommissioning (D and D) program requires buildings to be decontaminated, decommissioned, and surveyed for radiological contamination in an expeditious and cost-effective manner. Simultaneously, the health and safety of personnel involved in the D and D activities is of primary concern. D and D workers must perform duties high off the ground, requiring the use of manlifts or scaffolding, often, in radiologically or chemically contaminated areas or in areas with limited access. Survey and decontamination instruments that are used are sometimes heavy or awkward to use, particularly when the worker is operating from a manlift or scaffolding. Finding alternative methods of performing such work on manlifts or scaffolding is important. The 2-D Linear Motion System (2-D LMS), also known as the Wall Walker{trademark}, is designed to remotely position tools and instruments on walls for use in such activities as radiation surveys, decontamination, and painting. Traditional (baseline) methods for operating equipment for these tasks require workers to perform duties on elevated platforms, sometimes several meters above the ground surface and near potential sources of contamination. The Wall Walker 2-D LMS significantly improves health and safety conditions by facilitating remote operation of equipment. The Wall Walker 2-D LMS performed well in a demonstration of its precision, accuracy, maneuverability, payload capacity, and ease of use. Thus, this innovative technology is demonstrated to be a viable alternative to standard methods of performing work on large, high walls, especially those that have potential contamination concerns. The Wall Walker was used to perform a final release radiological survey on over 167 m{sup 2} of walls. In this application, surveying using a traditional (baseline) method that employs an aerial lift for manual access was 64% of the total cost of the improved technology. However, for areas over approximately 600 m{sup 2}, the Wall Walker would cost less than the baseline. Using the Wall Walker 2-D LMS, ALARA exposure and worker safety is improved, and there is potential for increased productivity. This innovative technology performed better than the baseline by providing real-time monitoring of the tool or instrument position. Also, the Wall Walker 2-D LMS can traverse any two-dimensional path at constant speeds of up to 18.3 linear meters per minute (60 linear feet per minute). The survey production rate for the innovative technology was about 0.6 m{sup 2}/min (6 ft{sup 2}/min); the baseline production rate was approximately 0.3 m{sup 2}/min (3 ft{sup 2}/min), using the same surveying instrument and maximum scanning rate.
Integrable Background Geometries
NASA Astrophysics Data System (ADS)
Calderbank, David M. J.
2014-03-01
This work has its origins in an attempt to describe systematically the integrable geometries and gauge theories in dimensions one to four related to twistor theory. In each such dimension, there is a nondegenerate integrable geometric structure, governed by a nonlinear integrable differential equation, and each solution of this equation determines a background geometry on which, for any Lie group G, an integrable gauge theory is defined. In four dimensions, the geometry is selfdual conformal geometry and the gauge theory is selfdual Yang-Mills theory, while the lower-dimensional structures are nondegenerate (i.e., non-null) reductions of this. Any solution of the gauge theory on a k-dimensional geometry, such that the gauge group H acts transitively on an ?-manifold, determines a (k+?)-dimensional geometry (k+??4) fibering over the k-dimensional geometry with H as a structure group. In the case of an ?-dimensional group H acting on itself by the regular representation, all (k+?)-dimensional geometries with symmetry group H are locally obtained in this way. This framework unifies and extends known results about dimensional reductions of selfdual conformal geometry and the selfdual Yang-Mills equation, and provides a rich supply of constructive methods. In one dimension, generalized Nahm equations provide a uniform description of four pole isomonodromic deformation problems, and may be related to the {SU}(?) Toda and dKP equations via a hodograph transformation. In two dimensions, the {Diff}(S^1) Hitchin equation is shown to be equivalent to the hyperCR Einstein-Weyl equation, while the {SDiff}(?^2) Hitchin equation leads to a Euclidean analogue of Plebanski's heavenly equations. In three and four dimensions, the constructions of this paper help to organize the huge range of examples of Einstein-Weyl and selfdual spaces in the literature, as well as providing some new ! ones. The nondegenerate reductions have a long ancestry. More ! recently , degenerate or null reductions have attracted increased interest. Two of these reductions and their gauge theories (arguably, the two most significant) are also described.
Rickard Jonsson; Hans Westman
2007-08-21
We show that by employing the standard projected curvature as a measure of spatial curvature, we can make a certain generalization of optical geometry (Abramowicz and Lasota 1997, Class. Quantum Grav. 14 (1997) A23). This generalization applies to any spacetime that admits a hypersurface orthogonal shearfree congruence of worldlines. This is a somewhat larger class of spacetimes than the conformally static spacetimes assumed in standard optical geometry. In the generalized optical geometry, which in the generic case is time dependent, photons move with unit speed along spatial geodesics and the sideways force experienced by a particle following a spatially straight line is independent of the velocity. Also gyroscopes moving along spatial geodesics do not precess (relative to the forward direction). Gyroscopes that follow a curved spatial trajectory precess according to a very simple law of three-rotation. We also present an inertial force formalism in coordinate representation for this generalization. Furthermore, we show that by employing a new sense of spatial curvature (Jonsson, Class. Quantum Grav. 23 (2006) 1) closely connected to Fermat's principle, we can make a more extensive generalization of optical geometry that applies to arbitrary spacetimes. In general this optical geometry will be time dependent, but still geodesic photons move with unit speed and follow lines that are spatially straight in the new sense. Also, the sideways experienced (comoving) force on a test particle following a line that is straight in the new sense will be independent of the velocity.
NASA Astrophysics Data System (ADS)
Jonsson, Rickard; Westman, Hans
2006-01-01
We show that by employing the standard projected curvature as a measure of spatial curvature, we can make a certain generalization of optical geometry (Abramowicz M A and Lasota J-P 1997 Class. Quantum Grav. A 14 23 30). This generalization applies to any spacetime that admits a hypersurface orthogonal shearfree congruence of worldlines. This is a somewhat larger class of spacetimes than the conformally static spacetimes assumed in standard optical geometry. In the generalized optical geometry, which in the generic case is time dependent, photons move with unit speed along spatial geodesics and the sideways force experienced by a particle following a spatially straight line is independent of the velocity. Also gyroscopes moving along spatial geodesics do not precess (relative to the forward direction). Gyroscopes that follow a curved spatial trajectory precess according to a very simple law of three-rotation. We also present an inertial force formalism in coordinate representation for this generalization. Furthermore, we show that by employing a new sense of spatial curvature (Jonsson R 2006 Class. Quantum Grav. 23 1)) closely connected to Fermat's principle, we can make a more extensive generalization of optical geometry that applies to arbitrary spacetimes. In general this optical geometry will be time dependent, but still geodesic photons move with unit speed and follow lines that are spatially straight in the new sense. Also, the sideways experienced (comoving) force on a test particle following a line that is straight in the new sense will be independent of the velocity.
Calculation of wakefields in 2D rectangular structures
NASA Astrophysics Data System (ADS)
Zagorodnov, I.; Bane, K. L. F.; Stupakov, G.
2015-10-01
We consider the calculation of electromagnetic fields generated by an electron bunch passing through a vacuum chamber structure that, in general, consists of an entry pipe, followed by some kind of transition or cavity, and ending in an exit pipe. We limit our study to structures having rectangular cross section, where the height can vary as function of longitudinal coordinate but the width and side walls remain fixed. For such structures, we derive a Fourier representation of the wake potentials through one-dimensional functions. A new numerical approach for calculating the wakes in such structures is proposed and implemented in the computer code echo(2d). The computation resource requirements for this approach are moderate and comparable to those for finding the wakes in 2D rotationally symmetric structures. Numerical examples obtained with the new numerical code are presented.
Development of 2D Ionization Chamber for Particle Therapy
NASA Astrophysics Data System (ADS)
Ho, Chi-Li
2010-11-01
Recently rapid growth in particle therapy has imposed new detector developments for quality assurance (QA) purposes. Relatively high dose deposition from proton or carbon ion beam requires stringent performance from detectors. Cyclotron, synchrotron, or future laser driven accelerators represent DC and pulse sources which need different timing designs in electronics. Dose and position measurements of particle beams can serve clinical, beam diagnosis and QA purposes. We categorize the parameters of detectors - electronics, DAQ, and simulation--to serve for later optimizations. Gaseous detector is preferred because of its radiation hardness, and operation at ionization mode provides stable condition. We present our progresses in 2D ionization chamber development. Basic studies are carried out on 1D ionization chamber, which consists of 16 6-mm-wide strips. Results of measuring electron and proton beams are compared with MC simulations. 2D array ionization chamber design is optimized and based on 1D prototype measurements.
Visualization of 2-D and 3-D Tensor Fields
NASA Technical Reports Server (NTRS)
Hesselink, Lambertus
1995-01-01
In previous work we have developed a novel approach to visualizing second order symmetric 2-D tensor fields based on degenerate point analysis. At degenerate points the eigenvalues are either zero or equal to each other, and the hyperstreamlines about these points give rise to trisector or wedge points. These singularities and their connecting hyperstreamlines determine the topology of the tensor field. In this study we are developing new methods for analyzing and displaying 3-D tensor fields. This problem is considerably more difficult than the 2-D one, as the richness of the data set is much larger. Here we report on our progress and a novel method to find, analyze and display 3-D degenerate points. First we discuss the theory, then an application involving a 3-D tensor field, the Boussinesq problem with two forces.
Visualization of 2-D and 3-D Tensor Fields
NASA Technical Reports Server (NTRS)
Hesselink, Lambertus
1997-01-01
In previous work we have developed a novel approach to visualizing second order symmetric 2-D tensor fields based on degenerate point analysis. At degenerate points the eigenvalues are either zero or equal to each other, and the hyper-streamlines about these points give rise to tri-sector or wedge points. These singularities and their connecting hyper-streamlines determine the topology of the tensor field. In this study we are developing new methods for analyzing and displaying 3-D tensor fields. This problem is considerably more difficult than the 2-D one, as the richness of the data set is much larger. Here we report on our progress and a novel method to find , analyze and display 3-D degenerate points. First we discuss the theory, then an application involving a 3-D tensor field, the Boussinesq problem with two forces.
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.
Controlling avalanche criticality in 2D nano arrays
Zohar, Y. C.; Yochelis, S.; Dahmen, K. A.; Jung, G.; Paltiel, Y.
2013-01-01
Many physical systems respond to slowly changing external force through avalanches spanning broad range of sizes. Some systems crackle even without apparent external force, such as bursts of neuronal activity or charge transfer avalanches in 2D molecular layers. Advanced development of theoretical models describing disorder-induced critical phenomena calls for experiments probing the dynamics upon tuneable disorder. Here we show that isomeric structural transitions in 2D organic self-assembled monolayer (SAM) exhibit critical dynamics with experimentally tuneable disorder. The system consists of field effect transistor coupled through SAM to illuminated semiconducting nanocrystals (NCs). Charges photoinduced in NCs are transferred through SAM to the transistor surface and modulate its conductivity. Avalanches of isomeric structural transitions are revealed by measuring the current noise I(t) of the transistor. Accumulated surface traps charges reduce dipole moments of the molecules, decrease their coupling, and thus decrease the critical disorder of the SAM enabling its tuning during experiments. PMID:23677142
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.
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.
CBEAM. 2-D: a two-dimensional beam field code
Dreyer, K.A.
1985-05-01
CBEAM.2-D is a two-dimensional solution of Maxwell's equations for the case of an electron beam propagating through an air medium. Solutions are performed in the beam-retarded time frame. Conductivity is calculated self-consistently with field equations, allowing sophisticated dependence of plasma parameters to be handled. A unique feature of the code is that it is implemented on an IBM PC microcomputer in the BASIC language. Consequently, it should be available to a wide audience.
Statistical analysis of quiet stance sway in 2-D
DiZio, Paul; Lackner, James R.
2014-01-01
Subjects exposed to a rotating environment that perturbs their postural sway show adaptive changes in their voluntary spatially directed postural motion to restore accurate movement paths but do not exhibit any obvious learning during passive stance. We have found, however, that a variable known to characterize the degree of stochasticity in quiet stance can also reveal subtle learning phenomena in passive stance. We extended Chow and Collins (Phys Rev E 52(1):909–912, 1995) one-dimensional pinned-polymer model (PPM) to two dimensions (2-D) and then evaluated the model’s ability to make analytical predictions for 2-D quiet stance. To test the model, we tracked center of mass and centers of foot pressures, and compared and contrasted stance sway for the anterior–posterior versus medio-lateral directions before, during, and after exposure to rotation at 10 rpm. Sway of the body during rotation generated Coriolis forces that acted perpendicular to the direction of sway. We found significant adaptive changes for three characteristic features of the mean square displacement (MSD) function: the exponent of the power law defined at short time scales, the proportionality constant of the power law, and the saturation plateau value defined at longer time scales. The exponent of the power law of MSD at a short time scale lies within the bounds predicted by the 2-D PPM. The change in MSD during exposure to rotation also had a power-law exponent in the range predicted by the theoretical model. We discuss the Coriolis force paradigm for studying postural and movement control and the applicability of the PPM model in 2-D for studying postural adaptation. PMID:24477760
Fully automated 2D-3D registration and verification.
Varnavas, Andreas; Carrell, Tom; Penney, Graeme
2015-12-01
Clinical application of 2D-3D registration technology often requires a significant amount of human interaction during initialisation and result verification. This is one of the main barriers to more widespread clinical use of this technology. We propose novel techniques for automated initial pose estimation of the 3D data and verification of the registration result, and show how these techniques can be combined to enable fully automated 2D-3D registration, particularly in the case of a vertebra based system. The initialisation method is based on preoperative computation of 2D templates over a wide range of 3D poses. These templates are used to apply the Generalised Hough Transform to the intraoperative 2D image and the sought 3D pose is selected with the combined use of the generated accumulator arrays and a Gradient Difference Similarity Measure. On the verification side, two algorithms are proposed: one using normalised features based on the similarity value and the other based on the pose agreement between multiple vertebra based registrations. The proposed methods are employed here for CT to fluoroscopy registration and are trained and tested with data from 31 clinical procedures with 417 low dose, i.e. low quality, high noise interventional fluoroscopy images. When similarity value based verification is used, the fully automated system achieves a 95.73% correct registration rate, whereas a no registration result is produced for the remaining 4.27% of cases (i.e. incorrect registration rate is 0%). The system also automatically detects input images outside its operating range. PMID:26387052
Valley and electric photocurrents in 2D silicon and graphene
Tarasenko, S. A.; Ivchenko, E. L.; Olbrich, P.; Ganichev, S. D.
2013-12-04
We show that the optical excitation of multi-valley systems leads to valley currents which depend on the light polarization. The net electric current, determined by the vector sum of single-valley contributions, vanishes for some peculiar distributions of carriers in the valley and momentum spaces forming a pure valley current. We report on the study of this phenomenon, both experimental and theoretical, for graphene and 2D electron channels on the silicon surface.
Flow transitions in a 2D directional solidification model
NASA Technical Reports Server (NTRS)
Larroude, Philippe; Ouazzani, Jalil; Alexander, J. Iwan D.
1992-01-01
Flow transitions in a Two Dimensional (2D) model of crystal growth were examined using the Bridgman-Stockbarger me thod. Using a pseudo-spectral Chebyshev collocation method, the governing equations yield solutions which exhibit a symmetry breaking flow tansition and oscillatory behavior indicative of a Hopf bifurcation at higher values of Ra. The results are discussed from fluid dynamic viewpoint, and broader implications for process models are also addressed.
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.
Random Thoughts on Thermal Design 2-D Thermal Energy Transfer
Groppi, Christopher
Random Thoughts on Thermal Design #12;2-D Thermal Energy Transfer 5.46x10-12 12 1+2-12 (1 4 - 2 4......................... 0.008 to 0.036 · Stainless Steel.................... 0.048 to 0.074 · Tin Foil (clean of power and an external compressor. #12;Gas Conduction Mean free path = 1 2 n = molecules per unit
Valley and spin currents in 2D transition metal dichalcogenides
NASA Astrophysics Data System (ADS)
Yao, Wang
2015-03-01
In two-dimensional (2D) transition metal dichalcogenides (TMDs), carriers are indexed by both the spin and the valley pseudospin (labelling the degenerate band extrema in momentum space). 2D TMDs is therefore an ideal laboratory for exploring these internal quantum degrees of freedom for new electronics, and controlling the flow of spin and pseudospin is at the heart of such applications. We will discuss two mechanisms for generating spin and valley currents of electrons in 2D group-VIB TMDs: (I) the valley and spin Hall effects arising from the Berry curvatures; and (II) the nonlinear valley and spin currents arising from Fermi pocket anisotropy. The two effects have distinct scaling with the electric field, and different dependence of the current direction on the field direction and crystalline axis. We will discuss the possibility to observe and distinguish the two effects as distinct patterns of polarized electroluminescence at p-n junction in 2D TMDs. The nonlinear current response also makes possible the generation of pure spin and valley flows without net charge current, either by an AC bias or by an inhomogeneous temperature distribution. We will also discuss the valley Hall effect of charged excitons in monolayer TMDs, which arises from the effective coupling of the excitonic valley pseudospin to its center of mass motion by the exchange interaction between the electron and hole constituents. The work is supported by the Research Grant Council of Hong Kong SAR (HKU17305914P, HKU9/CRF/13G), and the Croucher Foundation under the Croucher Innovation Award.
Volumetric elasticity imaging with a 2-D CMUT array.
Fisher, Ted G; Hall, Timothy J; Panda, Satchi; Richards, Michael S; Barbone, Paul E; Jiang, Jingfeng; Resnick, Jeff; Barnes, Steve
2010-06-01
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 the similarity measure. Differences among the algorithms were the degree to which they tracked elevational motion: not at all (2-D search), planar search, combination of multiple planes and plane independent guided search. The cross-correlation between the predeformation and motion-compensated postdeformation RF echo fields was used to quantify motion tracking accuracy. The lesion contrast-to-noise ratio was used to quantify image quality. Tracking accuracy and strain image quality generally improved with increased tracking sophistication. When used as input for a 3-D modulus reconstruction, high quality 3-D displacement estimates yielded accurate and low noise modulus reconstruction. PMID:20510188
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
Toward naturalistic 2D-to-3D conversion.
Huang, Weicheng; Cao, Xun; Lu, Ke; Dai, Qionghai; Bovik, Alan Conrad
2015-02-01
Natural scene statistics (NSSs) models have been developed that make it possible to impose useful perceptually relevant priors on the luminance, colors, and depth maps of natural scenes. We show that these models can be used to develop 3D content creation algorithms that can convert monocular 2D videos into statistically natural 3D-viewable videos. First, accurate depth information on key frames is obtained via human annotation. Then, both forward and backward motion vectors are estimated and compared to decide the initial depth values, and a compensation process is applied to further improve the depth initialization. Then, the luminance/chrominance and initial depth map are decomposed by a Gabor filter bank. Each subband of depth is modeled to produce a NSS prior term. The statistical color-depth priors are combined with the spatial smoothness constraint in the depth propagation target function as a prior regularizing term. The final depth map associated with each frame of the input 2D video is optimized by minimizing the target function over all subbands. In the end, stereoscopic frames are rendered from the color frames and their associated depth maps. We evaluated the quality of the generated 3D videos using both subjective and objective quality assessment methods. The experimental results obtained on various sequences show that the presented method outperforms several state-of-the-art 2D-to-3D conversion methods. PMID:25546859
An Intercomparison of 2-D Models Within a Common Framework
NASA Technical Reports Server (NTRS)
Weisenstein, Debra K.; Ko, Malcolm K. W.; Scott, Courtney J.; Jackman, Charles H.; Fleming, Eric L.; Considine, David B.; Kinnison, Douglas E.; Connell, Peter S.; Rotman, Douglas A.; Bhartia, P. K. (Technical Monitor)
2002-01-01
A model intercomparison among the Atmospheric and Environmental Research (AER) 2-D model, the Goddard Space Flight Center (GSFC) 2-D model, and the Lawrence Livermore National Laboratory 2-D model allows us to separate differences due to model transport from those due to the model's chemical formulation. This is accomplished by constructing two hybrid models incorporating the transport parameters of the GSFC and LLNL models within the AER model framework. By comparing the results from the native models (AER and e.g. GSFC) with those from the hybrid model (e.g. AER chemistry with GSFC transport), differences due to chemistry and transport can be identified. For the analysis, we examined an inert tracer whose emission pattern is based on emission from a High Speed Civil Transport (HSCT) fleet; distributions of trace species in the 2015 atmosphere; and the response of stratospheric ozone to an HSCT fleet. Differences in NO(y) in the upper stratosphere are found between models with identical transport, implying different model representations of atmospheric chemical processes. The response of O3 concentration to HSCT aircraft emissions differs in the models from both transport-dominated differences in the HSCT-induced perturbations of H2O and NO(y) as well as from differences in the model represent at ions of O3 chemical processes. The model formulations of cold polar processes are found to be the most significant factor in creating large differences in the calculated ozone perturbations
Observations of 2D Doppler backscattering on MAST
Thomas, D A; Freethy, S J; Huang, B K; Shevchenko, V F; Vann, R G L
2015-01-01
The Synthetic Aperture Microwave Imaging (SAMI) diagnostic has conducted proof-of-principle 2D Doppler backscattering (DBS) experiments on MAST. SAMI actively probes the plasma edge using a wide (+-40 degrees vertical and horizontal) and tuneable (10-35.5 GHz) beam. The Doppler backscattered signal is digitised in vector form using an array of eight Vivaldi PCB antennas. This allows the receiving array to be focused in any direction within the field of view simultaneously to an angular range of 6-24 degrees FWHM at 10-34.5 GHz. This capability is unique to SAMI and is an entirely novel way of conducting DBS experiments. In this paper the feasibility of conducting 2D DBS experiments is explored. Initial measurements of phenomena observed on conventional DBS experiments are presented; such as momentum injection from neutral beams and an abrupt change in power and turbulence velocity coinciding with the onset of H-mode. In addition, being able to carry out 2D DBS imaging allows a measurement of magnetic pitch an...
On the effective shear speed in 2D phononic crystals
A. A. Kutsenko; A. L. Shuvalov; A. N. Norris; O. Poncelet
2011-06-27
The quasistatic limit of the antiplane shear-wave speed ('effective speed') $c$ in 2D periodic lattices is studied. Two new closed-form estimates of $c$ are derived by employing two different analytical approaches. The first proceeds from a standard background of the plane wave expansion (PWE). The second is a new approach, which resides in $\\mathbf{x}$-space and centers on the monodromy matrix (MM) introduced in the 2D case as the multiplicative integral, taken in one coordinate, of a matrix with components being the operators with respect to the other coordinate. On the numerical side, an efficient PWE-based scheme for computing $c$ is proposed and implemented. The analytical and numerical findings are applied to several examples of 2D square lattices with two and three high-contrast components, for which the new PWE and MM estimates are compared with the numerical data and with some known approximations. It is demonstrated that the PWE estimate is most efficient in the case of densely packed stiff inclusions, especially when they form a symmetric lattice, while in general it is the MM estimate that provides the best overall fitting accuracy.
Geometries with intransitive equivalence relation
Yuri A. Rylov
2009-03-30
One considers geometry with the intransitive equaivalence relation. Such a geometry is a physical geometry, i.e. it is described completely by the world function, which is a half of the squared distance function. The physical geometry cannot be axiomatized, in general. It is obtained as a result of deformation of the proper Euclidean geometry. Class of physical geometries is more powerful, than the class of axiomatized geometries. The physical geometry admits one to describe such geometric properties as discreteness, granularity and limited divisibility. These properties are important in application to the space-time. They admits one to explain the discrimination properties of the space-time, which generate discrete parameters of elementary particles. Mathematical formalism of a physical geometry is very simple. The physical geometry is formulated in geometrical terms (in terms of points and world function) without a use of means of description (coordinate system, space dimension, manifold, etc.).
Strings on Bubbling Geometries
Hai Lin; Alexander Morisse; Jonathan P. Shock
2011-07-27
We study gauge theory operators which take the form of a product of a trace with a Schur polynomial, and their string theory duals. These states represent strings excited on bubbling AdS geometries which are dual to the Schur polynomials. These geometries generically take the form of multiple annuli in the phase space plane. We study the coherent state wavefunction of the lattice, which labels the trace part of the operator, for a general Young tableau and their dual description on the droplet plane with a general concentric ring pattern. In addition we identify a density matrix over the coherent states on all the geometries within a fixed constraint. This density matrix may be used to calculate the entropy of a given ensemble of operators. We finally recover the BMN string spectrum along the geodesic near any circle from the ansatz of the coherent state wavefunction.
Strings on bubbling geometries
NASA Astrophysics Data System (ADS)
Lin, Hai; Morisse, Alexander; Shock, Jonathan P.
2010-06-01
We study gauge theory operators which take the form of a product of a trace with a Schur polynomial, and their string theory duals. These states represent strings excited on bubbling AdS geometries which are dual to the Schur polynomials. These geometries generically take the form of multiple annuli in the phase space plane. We study the coherent state wavefunction of the lattice, which labels the trace part of the operator, for a general Young tableau and their dual description on the droplet plane with a general concentric ring pattern. In addition we identify a density matrix over the coherent states on all the geometries within a fixed constraint. This density matrix may be used to calculate the entropy of a given ensemble of operators. We finally recover the BMN string spectrum along the geodesic near any circle from the ansatz of the coherent state wave-function.
Strings on Bubbling Geometries
Lin, Hai; Shock, Jonathan P
2010-01-01
We study gauge theory operators which take the form of a product of a trace with a Schur polynomial, and their string theory duals. These states represent strings excited on bubbling AdS geometries which are dual to the Schur polynomials. These geometries generically take the form of multiple annuli in the phase space plane. We study the coherent state wavefunction of the lattice, which labels the trace part of the operator, for a general Young tableau and their dual description on the droplet plane with a general concentric ring pattern. In addition we identify a density matrix over the coherent states on all the geometries within a fixed constraint. This density matrix may be used to calculate the entropy of a given ensemble of operators. We finally recover the BMN string spectrum along the geodesic near any circle from the ansatz of the coherent state wavefunction.
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...
NASA Astrophysics Data System (ADS)
Ochiai, T.; Nacher, J. C.
2011-09-01
Recently, the application of geometry and conformal mappings to artificial materials (metamaterials) has attracted the attention in various research communities. These materials, characterized by a unique man-made structure, have unusual optical properties, which materials found in nature do not exhibit. By applying the geometry and conformal mappings theory to metamaterial science, it may be possible to realize so-called "Harry Potter cloaking device". Although such a device is still in the science fiction realm, several works have shown that by using such metamaterials it may be possible to control the direction of the electromagnetic field at will. We could then make an object hidden inside of a cloaking device. Here, we will explain how to design invisibility device using differential geometry and conformal mappings.
New Design of Integrated 2D Photonic Crystal Narrow Band Filters Using the FDTD-2D Method
NASA Astrophysics Data System (ADS)
Badaoui, Hadjira Abri; Abri, Mehadji
2014-11-01
In this paper, integrated 2D photonic crystal narrow band filter design is achieved based on transmission spectra shift. The presented effective technique for the design of narrow band resonant filters obtained by one-missing-row and by choosing proper radii of air holes of the waveguide is proposed. The 2D photonic crystals are designed by utilizing cascaded waveguides with different radii of air holes. The results are presented for normal incident wave with TE polarizations with a narrow spectral bandwidth centered at ? = 1.55 ?m. We also discuss the filtering process and its necessary modifications to achieve efficient filtering. A final synthesized filter topology is presented and a band from 1.53 ?m to 1.57 ?m around 1.55 ?m is transmitted with a maximum transmission of about 77% with better performances is achieved.
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…
Analysis Strategy of Powder Diffraction Data with 2-D Detector
Kumar, Abhik; /SLAC, SSRL
2006-01-25
To gain a clearer understanding of orientation and grain deformation of crystalline materials, x-ray powder diffraction has played an integral role in extracting three-dimensional structural information from one-dimensional diffraction patterns. Powder diffraction models identical geometry to the intersection of a normal right cone with a plane. The purpose of this paper is to develop a general expression defining the conic sections based on the geometry of a powder diffraction experiment. Applying the derived formulation of a diffraction arc to experimental data will give insight to the molecular and structural properties of the sample in question. Instead of using complex three-dimensional Euclidian geometry, we define the problem solving technique with a simpler two-dimensional transformation approach to arrive at the final equation describing the conic sections. Using the diffraction geometry parameters, we can use this equation to calibrate the diffractometer from the diffraction pattern of a known reference material, or to determine the crystalline lattice structure of the compound.
2D hyperbolic groups induce three-periodic euclidean reticulations
Robins, Vanessa
periodic minimal surfaces (TPMS). Formally this is done by constructing a covering map from the hyper overview follows. We view 3D crystalline reticulations as decorations of TPMS -- a concept in the differential geometry of TPMS [8] and in tiling theory [9, 10, 11, 12] are proving indispensable to progress
50 CFR Table 2d to Part 679 - Species Codes-Non-FMP Species
Code of Federal Regulations, 2011 CFR
2011-10-01
... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Species Codes-Non-FMP Species 2d Table 2d... ALASKA Pt. 679, Table 2d Table 2d to Part 679—Species Codes—Non-FMP Species General use Species description Code Arctic char, anadromous 521 Dolly varden, anadromous 531 Eels or eel-like fish 210 Eel,...
50 CFR Table 2d to Part 679 - Species Codes-Non-FMP Species
Code of Federal Regulations, 2013 CFR
2013-10-01
... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Species Codes-Non-FMP Species 2d Table 2d... ALASKA Pt. 679, Table 2d Table 2d to Part 679—Species Codes—Non-FMP Species General use Species description Code Arctic char, anadromous 521 Dolly varden, anadromous 531 Eels or eel-like fish 210 Eel,...
50 CFR Table 2d to Part 679 - Species Codes-Non-FMP Species
Code of Federal Regulations, 2012 CFR
2012-10-01
... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Species Codes-Non-FMP Species 2d Table 2d... ALASKA Pt. 679, Table 2d Table 2d to Part 679—Species Codes—Non-FMP Species General use Species description Code Arctic char, anadromous 521 Dolly varden, anadromous 531 Eels or eel-like fish 210 Eel,...
Spatially encoded NMR and the acquisition of 2D magnetic resonance images within a single scan
Frydman, Lucio
Spatially encoded NMR and the acquisition of 2D magnetic resonance images within a single scan Yoav acquisition schemes toward the collection of two-dimen- sional magnetic resonance imaging (2D MRI) data resonance imaging (MRI). In spite of the dissimilar information being sought in 2D NMR and 2D MRI
Interactive 3D Facial Expression Posing through 2D Portrait Manipulation Tanasai Sucontphunt
Deng, Zhigang
Interactive 3D Facial Expression Posing through 2D Portrait Manipulation Tanasai Sucontphunt Dept: The top row shows 2D portraits edited by users. The bottom row shows generated 3D facial expressions through 2D portrait manipulation, where a manipulated 2D portrait serves a metaphor for automatically
Preliminary abatement device evaluation: 1D-2D KGM cyclone design
Technology Transfer Automated Retrieval System (TEKTRAN)
Cyclones are predominately used in controlling cotton gin particulate matter (PM) emissions. The most commonly used cyclone designs are the 2D-2D and 1D-3D; however other designs such as the 1D-2D KGM have or are currently being used. A 1D-2D cyclone has a barrel length equal to the barrel diamete...
NASA Astrophysics Data System (ADS)
Garaud, Pascale; Brummell, Nicholas
2015-12-01
Fingering convection (otherwise known as thermohaline convection) is an instability that occurs in stellar radiative interiors in the presence of unstable compositional gradients. Numerical simulations have been used in order to estimate the efficiency of mixing induced by this instability. However, fully three-dimensional (3D) computations in the parameter regime appropriate for stellar astrophysics (i.e., low Prandtl number) are prohibitively expensive. This raises the question of whether two-dimensional (2D) simulations could be used instead to achieve the same goals. In this work, we address this issue by comparing the outcome of 2D and 3D simulations of fingering convection at low Prandtl number. We find that 2D simulations are never appropriate. However, we also find that the required 3D computational domain does not have to be very wide: the third dimension only needs to contain a minimum of two wavelengths of the fastest-growing linearly unstable mode to capture the essentially 3D dynamics of small-scale fingering. Narrow domains, however, should still be used with caution since they could limit the subsequent development of any large-scale dynamics typically associated with fingering convection.
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 Å ± 0.5 Å, twist angle ?12 = 5° ± 5°), which differs from the conformation of such adjacent bases in duplex DNA. These experiments establish UV-2D FS as a method for examining the local conformations of an adjacent pair of fluorescent nucleotides substituted into specific DNA or RNA constructs, which will serve as a powerful probe to interpret, in structural terms, biologically significant local conformational changes within the nucleic acid framework of protein-nucleic acid complexes. PMID:24223491
Stöbe, Stephan; Tarr, Adrienn; Pfeiffer, Dietrich; Hagendorff, Andreas
2014-01-01
Comparison of 3D and 2D speckle tracking performed on standard 2D and triplane 2D datasets of normal and pathological left ventricular (LV) wall-motion patterns with a focus on the effect that 3D volume rate (3DVR), image quality and tracking artifacts have on the agreement between 2D and 3D speckle tracking. 37 patients with normal LV function and 18 patients with ischaemic wall-motion abnormalities underwent 2D and 3D echocardiography, followed by offline speckle tracking measurements. The values of 3D global, regional and segmental strain were compared with the standard 2D and triplane 2D strain values. Correlation analysis with the LV ejection fraction (LVEF) was also performed. The 3D and 2D global strain values correlated good in both normally and abnormally contracting hearts, though systematic differences between the two methods were observed. Of the 3D strain parameters, the area strain showed the best correlation with the LVEF. The numerical agreement of 3D and 2D analyses varied significantly with the volume rate and image quality of the 3D datasets. The highest correlation between 2D and 3D peak systolic strain values was found between 3D area and standard 2D longitudinal strain. Regional wall-motion abnormalities were similarly detected by 2D and 3D speckle tracking. 2DST of triplane datasets showed similar results to those of conventional 2D datasets. 2D and 3D speckle tracking similarly detect normal and pathological wall-motion patterns. Limited image quality has a significant impact on the agreement between 3D and 2D numerical strain values. PMID:26693303
Koh, Kwi Hye; Pan, Xian; Zhang, Wei; McLachlan, Alan; Urrutia, Raul
2014-01-01
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
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.
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
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".…
Algebraic Thinking and Geometry
ERIC Educational Resources Information Center
Grandau, Laura; Stephens, Ana C.
2006-01-01
This article describes how two middle school teachers incorporated algebraic thinking into their textbook-based geometry lessons. One teacher embedded algebraic concepts within an existing textbook lesson while the other teacher elicited algebraic thinking by extending a textbook lesson. (Contains 5 figures.)
Advanced Review Geometry optimization
Schlegel, H. Bernhard
of most computational chemistry studies that are concerned with the structure and/or reactivity part of most quantum chemical calcu- lations. This article surveys methods for optimizing equilibrium geometries, lo- cating transition structures, and following reaction paths. The emphasis is on optimizations
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.
ERIC Educational Resources Information Center
Cooper, Brett D.; Barger, Rita
2009-01-01
The many connections between music and mathematics are well known. The length of a plucked string determines its tone, the time signature of a piece of music is a ratio, and note durations are measured in fractions. One connection commonly overlooked is that between music and geometry--specifically, geometric transformations, including…
Towards relativistic quantum geometry
NASA Astrophysics Data System (ADS)
Ridao, Luis Santiago; Bellini, Mauricio
2015-12-01
We obtain a gauge-invariant relativistic quantum geometry by using a Weylian-like manifold with a geometric scalar field which provides a gauge-invariant relativistic quantum theory in which the algebra of the Weylian-like field depends on observers. An example for a Reissner-Nordström black-hole is studied.
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)
Atiyah, Michael; Dijkgraaf, Robbert; Hitchin, Nigel
2010-01-01
We review the remarkably fruitful interactions between mathematics and quantum physics in the past decades, pointing out some general trends and highlighting several examples, such as the counting of curves in algebraic geometry, invariants of knots and four-dimensional topology. PMID:20123740
COMPUTATIONAL REAL ALGEBRAIC GEOMETRY
Mishra, Bud
geometry studies various algorithmic questions dealing with the real solutions of a system of equalities by the power and elegance with which it solves a broad and general class of problems arising in robotics, vision, computer aided design, geometric theorem proving, etc. The algorithmic problems that arise
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.
Experimental and Computational Study of Multiphase Flow Hydrodynamics in 2D Trickle Bed Reactors
NASA Astrophysics Data System (ADS)
Nadeem, H.; Ben Salem, I.; Kurnia, J. C.; Rabbani, S.; Shamim, T.; Sassi, M.
2014-12-01
Trickle bed reactors are largely used in the refining processes. Co-current heavy oil and hydrogen gas flow downward on catalytic particle bed. Fine particles in the heavy oil and/or soot formed by the exothermic catalytic reactions deposit on the bed and clog the flow channels. This work is funded by the refining company of Abu Dhabi and aims at mitigating pressure buildup due to fine deposition in the TBR. In this work, we focus on meso-scale experimental and computational investigations of the interplay between flow regimes and the various parameters that affect them. A 2D experimental apparatus has been built to investigate the flow regimes with an average pore diameter close to the values encountered in trickle beds. A parametric study is done for the development of flow regimes and the transition between them when the geometry and arrangement of the particles within the porous medium are varied. Liquid and gas flow velocities have also been varied to capture the different flow regimes. Real time images of the multiphase flow are captured using a high speed camera, which were then used to characterize the transition between the different flow regimes. A diffused light source was used behind the 2D Trickle Bed Reactor to enhance visualizations. Experimental data shows very good agreement with the published literature. The computational study focuses on the hydrodynamics of multiphase flow and to identify the flow regime developed inside TBRs using the ANSYS Fluent Software package. Multiphase flow inside TBRs is investigated using the "discrete particle" approach together with Volume of Fluid (VoF) multiphase flow modeling. The effect of the bed particle diameter, spacing, and arrangement are presented that may be used to provide guidelines for designing trickle bed reactors.
A novel time dependent gamma evaluation function for dynamic 2D and 3D dose distributions
NASA Astrophysics Data System (ADS)
Podesta, Mark; CGG Persoon, Lucas; Verhaegen, Frank
2014-10-01
Modern external beam radiotherapy requires detailed verification and quality assurance so that confidence can be placed on both the delivery of a single treatment fraction and on the consistency of delivery throughout the treatment course. To verify dose distributions, a comparison between prediction and measurement must be made. Comparisons between two dose distributions are commonly performed using a Gamma evaluation which is a calculation of two quantities on a pixel by pixel basis; the dose difference, and the distance to agreement. By providing acceptance criteria (e.g. 3%, 3?mm), the function will find the most appropriate match within its two degrees of freedom. For complex dynamic treatments such as IMRT or VMAT it is important to verify the dose delivery in a time dependent manner and so a gamma evaluation that includes a degree of freedom in the time domain via a third parameter, time to agreement, is presented here. A C++ (mex) based gamma function was created that could be run on either CPU and GPU computing platforms that would allow a degree of freedom in the time domain. Simple test cases were created in both 2D and 3D comprising of simple geometrical shapes with well-defined boundaries varying over time. Changes of varying magnitude in either space or time were introduced and repeated gamma analyses were performed varying the criteria. A clinical VMAT case was also included, artificial air bubbles of varying size were introduced to a patient geometry, along with shifts of varying magnitude in treatment time. For all test cases where errors in distance, dose or time were introduced, the time dependent gamma evaluation could accurately highlight the errors. The time dependent gamma function presented here allows time to be included as a degree of freedom in gamma evaluations. The function allows for 2D and 3D data sets which are varying over time to be compared using appropriate criteria without penalising minor offsets of subsequent radiation fields in time.
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.
Electron delocalization patterns in models of distorted (D2d) mixed-valence cubanes
NASA Astrophysics Data System (ADS)
Marks, Alison J.
2008-08-01
Low-symmetry distortions are present in cubanes such as Fe4S4, but their effects on electron delocalization properties are not well-understood. Mixed-valence cubanes often exhibit experimentally measurable ``pair delocalization'' of a delocalizable electron. An important question is, what is the role of physical interactions (vibronic, electronic, exchange) and symmetry distortions in determining the electron delocalization pattern? Semiclassical models are used to explore the electron delocalization patterns of S=12 tetragonally (D2d) distorted mixed-valence cubanes comprising four metal centers with bridging ligands, a single delocalizable ``excess'' electron, and either closed-shell or open-shell ion cores. Phase diagrams show that distorted S=12 ground state cubanes with antiferromagnetic exchange (as found in nature) have delocalization patterns qualitatively similar to those of an S=12 model with no Heisenberg exchange, suggesting that exchange is not necessarily a dominant factor in determining electron delocalization properties. The open-shell model reveals two types of pair delocalization for the S=12 ground state, with differing dimer subunit spins for compressed and elongated geometries. Previous studies emphasize the importance of exchange interactions for pair delocalization. Here, it is shown that electron exchange is not always necessary for pair delocalization and that it can be achieved with relatively small tetragonal distortions from tetrahedral (Td) symmetry. The results contradict those of an earlier theoretical study of distorted Fe4S4 clusters, which concluded that distortions of lower symmetry than D2d are necessary to induce a transition to pair delocalization.
2D Seismic Reflection Data across Central Illinois
Smith, Valerie; Leetaru, Hannes
2014-09-30
In a continuing collaboration with the Midwest Geologic Sequestration Consortium (MGSC) on the Evaluation of the Carbon Sequestration Potential of the Cambro-Ordovician Strata of the Illinois and Michigan Basins project, Schlumberger Carbon Services and WesternGeco acquired two-dimensional (2D) seismic data in the Illinois Basin. This work included the design, acquisition and processing of approximately 125 miles of (2D) seismic reflection surveys running west to east in the central Illinois Basin. Schlumberger Carbon Services and WesternGeco oversaw the management of the field operations (including a pre-shoot planning, mobilization, acquisition and de-mobilization of the field personnel and equipment), procurement of the necessary permits to conduct the survey, post-shoot closure, processing of the raw data, and provided expert consultation as needed in the interpretation of the delivered product. Three 2D seismic lines were acquired across central Illinois during November and December 2010 and January 2011. Traversing the Illinois Basin, this 2D seismic survey was designed to image the stratigraphy of the Cambro-Ordovician sections and also to discern the basement topography. Prior to this survey, there were no regionally extensive 2D seismic data spanning this section of the Illinois Basin. Between the NW side of Morgan County and northwestern border of Douglas County, these seismic lines ran through very rural portions of the state. Starting in Morgan County, Line 101 was the longest at 93 miles in length and ended NE of Decatur, Illinois. Line 501 ran W-E from the Illinois Basin – Decatur Project (IBDP) site to northwestern Douglas County and was 25 miles in length. Line 601 was the shortest and ran N-S past the IBDP site and connected lines 101 and 501. All three lines are correlated to well logs at the IBDP site. Originally processed in 2011, the 2D seismic profiles exhibited a degradation of signal quality below ~400 millisecond (ms) which made interpretation of the Mt. Simon and Knox sections difficult. The data quality also gradually decreased moving westward across the state. To meet evolving project objectives, in 2012 the seismic data was re-processed using different techniques to enhance the signal quality thereby rendering a more coherent seismic profile for interpreters. It is believed that the seismic degradation could be caused by shallow natural gas deposits and Quaternary sediments (which include abandoned river and stream channels, former ponds, and swamps with peat deposits) that may have complicated or changed the seismic wavelet. Where previously limited by seismic coverage, the seismic profiles have provided valuable subsurface information across central Illinois. Some of the interpretations based on this survey included, but are not limited to: - Stratigraphy generally gently dips to the east from Morgan to Douglas County. - The Knox Supergroup roughly maintains its thickness. There is little evidence for faulting in the Knox. However, at least one resolvable fault penetrates the entire Knox section. - The Eau Claire Formation, the primary seal for the Mt. Simon Sandstone, appears to be continuous across the entire seismic profile. - The Mt. Simon Sandstone thins towards the western edge of the basin. As a result, the highly porous lowermost Mt. Simon section is absent in the western part of the state. - Overall basement dip is from west to east. - Basement topography shows evidence of basement highs with on-lapping patterns by Mt. Simon sediments. - There is evidence of faults within the lower Mt. Simon Sandstone and basement rock that are contemporaneous with Mt. Simon Sandstone deposition. These faults are not active and do not penetrate the Eau Claire Shale. It is believed that these faults are associated with a possible failed rifting event 750 to 560 million years ago during the breakup of the supercontinent Rodinia.
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.
Progress in 2D photonic crystal Fano resonance photonics
NASA Astrophysics Data System (ADS)
Zhou, Weidong; Zhao, Deyin; Shuai, Yi-Chen; Yang, Hongjun; Chuwongin, Santhad; Chadha, Arvinder; Seo, Jung-Hun; Wang, Ken X.; Liu, Victor; Ma, Zhenqiang; Fan, Shanhui
2014-01-01
In contrast to a conventional symmetric Lorentzian resonance, Fano resonance is predominantly used to describe asymmetric-shaped resonances, which arise from the constructive and destructive interference of discrete resonance states with broadband continuum states. This phenomenon and the underlying mechanisms, being common and ubiquitous in many realms of physical sciences, can be found in a wide variety of nanophotonic structures and quantum systems, such as quantum dots, photonic crystals, plasmonics, and metamaterials. The asymmetric and steep dispersion of the Fano resonance profile promises applications for a wide range of photonic devices, such as optical filters, switches, sensors, broadband reflectors, lasers, detectors, slow-light and non-linear devices, etc. With advances in nanotechnology, impressive progress has been made in the emerging field of nanophotonic structures. One of the most attractive nanophotonic structures for integrated photonics is the two-dimensional photonic crystal slab (2D PCS), which can be integrated into a wide range of photonic devices. The objective of this manuscript is to provide an in depth review of the progress made in the general area of Fano resonance photonics, focusing on the photonic devices based on 2D PCS structures. General discussions are provided on the origins and characteristics of Fano resonances in 2D PCSs. A nanomembrane transfer printing fabrication technique is also reviewed, which is critical for the heterogeneous integrated Fano resonance photonics. The majority of the remaining sections review progress made on various photonic devices and structures, such as high quality factor filters, membrane reflectors, membrane lasers, detectors and sensors, as well as structures and phenomena related to Fano resonance slow light effect, nonlinearity, and optical forces in coupled PCSs. It is expected that further advances in the field will lead to more significant advances towards 3D integrated photonics, flat optics, and flexible optoelectronics, with lasting impact in areas ranging from computing, communications, to sensing and imaging systems.
Ultrathin 2D Metal-Organic Framework Nanosheets.
Zhao, Meiting; Wang, Yixian; Ma, Qinglang; Huang, Ying; Zhang, Xiao; Ping, Jianfeng; Zhang, Zhicheng; Lu, Qipeng; Yu, Yifu; Xu, Huan; Zhao, Yanli; Zhang, Hua
2015-12-01
A facile surfactant-assisted bottom-up synthetic method to prepare a series of freestanding ultrathin 2D M-TCPP (M = Zn, Cu, Cd or Co, TCPP = tetrakis(4-carboxyphenyl)porphyrin) nanosheets with a thickness of sub-10 nm is developed. As a proof-of-concept application, some of them are successfully used as new platforms for DNA detection. The Cu-TCPP nanosheet-based sensor shows excellent fluorescent sensing performance and is used for the simultaneous detection of multiple DNA targets. PMID:26468970
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.
2D Magneto-optical trapping of diatomic molecules.
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. PMID:25166984
Convective patterns in a 2d mantle convection simulation
NASA Astrophysics Data System (ADS)
Weismüller, Jens; Mohr, Marcus; Bunge, Hans-Peter
2013-04-01
One of the great challenges in deep mantle physics is to develop a quantitative understanding of the dynamic processes that govern mantle convection, so that we can ascertain their respective influence from the data we have available from seismic tomography as well as magnetic observations. In this context, we explore the behaviour of convection patterns in a 2d Boussinesq fluid and analyze the emerging convection patterns in detail, so that we can later quantify the influence of more complex processes like anelasticity, complex rheologies and mineralogical composition.
Quantifying Therapeutic and Diagnostic Efficacy in 2D Microvascular Images
NASA Technical Reports Server (NTRS)
Parsons-Wingerter, Patricia; Vickerman, Mary B.; Keith, Patricia A.
2009-01-01
VESGEN is a newly automated, user-interactive program that maps and quantifies the effects of vascular therapeutics and regulators on microvascular form and function. VESGEN analyzes two-dimensional, black and white vascular images by measuring important vessel morphology parameters. This software guides the user through each required step of the analysis process via a concise graphical user interface (GUI). Primary applications of the VESGEN code are 2D vascular images acquired as clinical diagnostic images of the human retina and as experimental studies of the effects of vascular regulators and therapeutics on vessel remodeling.
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.
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. Supported by DOE-Basic Energy Science DOE-BES-DMS (DEFG02-99ER45795). Computing resources are provided by NERSC and OSC.
2D/3D Synthetic Vision Navigation Display
NASA Technical Reports Server (NTRS)
Prinzel, Lawrence J., III; Kramer, Lynda J.; Arthur, J. J., III; Bailey, Randall E.; Sweeters, jason L.
2008-01-01
Flight-deck display software was designed and developed at NASA Langley Research Center to provide two-dimensional (2D) and three-dimensional (3D) terrain, obstacle, and flight-path perspectives on a single navigation display. The objective was to optimize the presentation of synthetic vision (SV) system technology that permits pilots to view multiple perspectives of flight-deck display symbology and 3D terrain information. Research was conducted to evaluate the efficacy of the concept. The concept has numerous unique implementation features that would permit enhanced operational concepts and efficiencies in both current and future aircraft.
MHD instabilities in accretion mounds - 1: 2D axisymmetric simulations
Mukherjee, Dipanjan; Mignone, Andrea
2012-01-01
We have performed stability analysis of axisymmetric accretion mounds on neutron stars in High Mass X-ray Binaries (HMXB) by 2-D MHD simulations with the PLUTO MHD code. We find that the mounds are stable with respect to interchange instabilities, but addition of excess mass destabilizes the equilibria. Our simulations confirm that accretion mounds are unstable with respect to MHD instabilities beyond a threshold mass. We investigate both filled and hollow mounds and the for the latter also compute the expected profile of cyclotron resonance scattering features (CRSF). In comparison to CRSF from filled mounds reported in our earlier work, hollow mounds display wider and more complex line profiles.
Exact results at the 2-D percolation point
P. Kleban; R. M. Ziff
1997-09-25
We derive exact expressions for the excess number of clusters b and the excess cumulants b_n of a related quantity at the 2-D percolation point. High-accuracy computer simulations are in accord with our predictions. b is a finite-size correction to the Temperley-Lieb or Baxter-Temperley-Ashley formula for the number of clusters per site n_c in the infinite system limit; the bn correct bulk cumulants. b and b_n are universal, and thus depend only on the system's shape. Higher-order corrections show no apparent dependence on fractional powers of the system size.
Parallelization of the 2d Swendsen-Wang Algorithm
NASA Astrophysics Data System (ADS)
Hackl, R.; Matuttis, H.-G.; Singer, J. M.; Husslein, Th.; Morgenstern, I.
We implemented a parallel Swendsen-Wang algorithm for a 2D Ising system without magnetization in a host-node programming model. The simulations were performed on the Intel Hypercube IPSC/860. Our maximum number of updates/s on 32 nodes ist three times as high as in the implementation by Stauffer and Kertész on the same machine. With 32 processors we reach half the speed of the simulations by Tamayo and Flanigan on 256 nodes of a CM5. We discuss the non-equilibrium relaxation for the energy and the magnetization.
Algorithms for Warping of 2-D PAGE Maps.
Manfredi, Marcello; Robotti, Elisa; Marengo, Emilio
2016-01-01
Software-based image analysis of 2-D PAGE maps is an important step for the investigation of proteome. Warping algorithms, which are employed to register spots among gels, are able to overcome the difficulties due to the low reproducibility of this analytical technique. Over the years, the research of new matching and warping mathematical methods has allowed the development of several routine applications of easy-to-use software. This chapter describes common and basic spatial transformations used for the alignment of protein spots present in different gel maps; some recently new approaches are also presented. PMID:26611413
Beam-Plasma Instabilities in a 2D Yukawa Lattice
Kyrkos, S.; Kalman, G. J.; Rosenberg, M.
2009-06-05
We consider a 2D Yukawa lattice of grains, with a beam of other charged grains moving in the lattice plane. In contrast to Vlasov plasmas, where the electrostatic instability excited by the beam is only longitudinal, here both longitudinal and transverse instabilities of the lattice phonons can develop. We determine and compare the transverse and longitudinal growth rates. The growth rate spectrum in wave number space exhibits remarkable gaps where no instability can develop. Depending on the system parameters, the transverse instability can be selectively excited.
2D Poisson sigma models with gauged vectorial supersymmetry
NASA Astrophysics Data System (ADS)
Bonezzi, Roberto; Sundell, Per; Torres-Gomez, Alexander
2015-08-01
In this note, we gauge the rigid vectorial supersymmetry of the two-dimensional Poisson sigma model presented in arXiv:1503.05625. We show that the consistency of the construction does not impose any further constraints on the differential Poisson algebra geometry than those required for the ungauged model. We conclude by proposing that the gauged model provides a first-quantized framework for higher spin gravity.
Geometry independent game encapsulation for non-Euclidean geometries
de Figueiredo, Luiz Henrique
by engaging its players to immerse in the game's "alternative reality". The engagement generated by gamesGeometry independent game encapsulation for non-Euclidean geometries Filipe De´o Guimar~aes, Vin a ludic new approach to the presentation of non-Euclidean geometries by adapting classic games
Beam-Plasma Interaction in a 2D Complex Plasma
NASA Astrophysics Data System (ADS)
Kyrkos, Stamatios; Kalman, G. J.; Rosenberg, M.
2006-10-01
In a complex (dusty) plasma, penetrating ion or electron beams may lead to beam-plasma instabilities. The instability displays interesting new properties when either the plasma or the beam, or both, are strongly interacting^1. Foremost amongst them is the possible generation of transverse instabilities. We consider the case when a 2D plasma is in the crystalline phase, forming a lattice, and the beam is moving in the lattice plane. Both the grains and the beam particles interact through a realistic Yukawa potential. The beam particles are assumed to be weakly coupled to each other and to the lattice^2. Using the full phonon spectrum for a 2D hexagonal Yukawa lattice^3, we determine and compare the transverse and longitudinal growth rates. The behavior of the growth rates depends on the direction of the beam and on the relationship between the beam speed v and the longitudinal and transverse sound speeds sL, sT. For beam speeds between the longitudinal and transverse sound speeds, the transverse instability could be more important, because it appears at lower k values. ^1 G. J. Kalman and M. Rosenberg, J. Phys. A: Math. Gen. 36 5963 (2003) ^2 M. Rosenberg, G. J. Kalman, S. Kyrkos and Z. Donko, J. Phys. A: Math. Gen. 39 4613 (2006) ^3 T. Sullivan, G. J. Kalman, S. Kyrkos, P. Bakshi, M. Rosenberg and Z. Donko, J. Phys. A: Math. Gen. 39 4607 (2006)
Measurement of the diffractive structure function $F_2^{D(3)}$
Christophe Royon
1999-08-02
Measurements of the diffractive structure function $F_2^{D(3)}(x_{\\PO}, \\beta, Q^2)$, describing the process $ep \\to eXY$, are presented in the two kinematic regions $0.4 \\leq Q^2 \\leq 5$, ${\\rm GeV}^2$, $0.001 \\leq \\beta \\leq 0.65$, and $200 \\leq \\beta \\leq 800 {\\rm GeV^2}$, $0.4 \\leq \\beta \\leq 0.9$, both with $\\xpom < 0.05$, $M_{_Y} < 1.6 {\\rm GeV}$ and $|t| < 1.0 {\\rm GeV^2}$. Together with published measurements at intermediate $Q^2$, the data are compared with models based on QCD and Regge phenomenology. The diffractive trajectory is found to have an intercept larger than that describing soft hadronic data and consistent with that determined using previously published H1 measurements at intermediate $Q^2$ alone. The data are also parameterised using a QCD motivated model based on the exchange of two gluons from the proton. In this model, the higher twist contribution to $F_2^{D(3)}$ at large $\\beta$ is found to be important at low $Q^2$. The data are also compared with models based on BFKL dynamics.
Local currents in a 2D topological insulator.
Dang, Xiaoqian; Burton, J D; Tsymbal, Evgeny Y
2015-12-23
Symmetry protected edge states in 2D topological insulators are interesting both from the fundamental point of view as well as from the point of view of potential applications in nanoelectronics as perfectly conducting 1D channels and functional elements of circuits. Here using a simple tight-binding model and the Landauer-Büttiker formalism we explore local current distributions in a 2D topological insulator focusing on effects of non-magnetic impurities and vacancies as well as finite size effects. For an isolated edge state, we show that the local conductance decays into the bulk in an oscillatory fashion as explained by the complex band structure of the bulk topological insulator. We demonstrate that although the net conductance of the edge state is topologically protected, impurity scattering leads to intricate local current patterns. In the case of vacancies we observe vortex currents of certain chirality, originating from the scattering of current-carrying electrons into states localized at the edges of hollow regions. For finite size strips of a topological insulator we predict the formation of an oscillatory band gap in the spectrum of the edge states, the emergence of Friedel oscillations caused by an open channel for backscattering from an impurity and antiresonances in conductance when the Fermi energy matches the energy of the localized state created by an impurity. PMID:26610145
Defect Dynamics and Zipping of 2D Colloidal Crystallites
NASA Astrophysics Data System (ADS)
Bowley, Chris; Smullin, Sylvia; Ling, Xinsheng
1998-03-01
We use video microscopy to study defect dynamics in 2D colloidal (charged polystyrene microspheres) crystallites formed at the water-air interface. For small 2D crystallites, one might expect to see free edge dislocations in such small systems since the cost of forming such defects scales logarithmically with the size of the crystallite. But we found that as soon as an edge dislocation forms, it quickly moves to the edge of the crystallite and disappears. This is due to an attraction with an image dislocation outside the edge. As a result, most crystallites are defect-free during most of the time. Interesting things happen when two crystallites try to bind to each other, or zip together. A sharp transition occurs at the shared edge of the two crystallites during the zipping process. This is clearly manifested by a sudden change in the relative velocity between two drifting crystallites or a sudden re-orientation of one of the crystallites relative to the other. This work was supported by the startup funds and a Richard Salomon Faculty Research Award from Brown University.
Marginal fluctuations as instantons on M2/D2-branes
NASA Astrophysics Data System (ADS)
Naghdi, M.
2014-03-01
We introduce some (anti-) M/D-branes through turning on the corresponding field strengths of the 11- and 10-dimensional supergravity theories over spaces, where we use and for the internal spaces. Indeed, when we add M2/D2-branes on the same directions with the near horizon branes of the Aharony-Bergman-Jafferis-Maldacena model, all symmetries and supersymmetries are preserved trivially. In this case, we obtain a localized object just in the horizon. This normalizable bulk massless scalar mode is a singlet of and , and it agrees with a marginal boundary operator of the conformal dimension of . However, after performing a special conformal transformation, we see that the solution is localized in the Euclideanized space and is attributable to the included anti-M2/D2-branes, which are also necessary to ensure that there is no back-reaction. The resultant theory now breaks all supersymmetries to , while the other symmetries are so preserved. The dual boundary operator is then set up from the skew-whiffing of the representations and for the supercharges and scalars, respectively, while the fermions remain fixed in of the original theory. Besides, we also address another alternate bulk to boundary matching procedure through turning on one of the gauge fields of the full gauge group along the same lines with a similar situation to the one faced in the AdS/CFT correspondence. The latter approach covers the difficulty already faced with in the bulk-boundary matching procedure for as well.
Predicting non-square 2D dice probabilities
NASA Astrophysics Data System (ADS)
Pender, G. A. T.; Uhrin, M.
2014-07-01
The prediction of the final state probabilities of a general cuboid randomly thrown onto a surface is a problem that naturally arises in the minds of men and women familiar with regular cubic dice and the basic concepts of probability. Indeed, it was considered by Newton in 1664 (Newton 1967 The Mathematical Papers of Issac Newton vol I (Cambridge: Cambridge University Press) pp 60-1). In this paper we make progress on the 2D problem (which can be realized in 3D by considering a long cuboid, or alternatively a rectangular cross-sectioned dreidel). For the two-dimensional case we suggest that the ratio of the probabilities of landing on each of the two sides is given by \\frac{\\sqrt{{{k}^{2}}+{{l}^{2}}}-k}{\\sqrt{{{k}^{2}}+{{l}^{2}}}-l}\\frac{arctan \\frac{l}{k}}{arctan \\frac{k}{l}} where k and l are the lengths of the two sides. We test this theory both experimentally and computationally, and find good agreement between our theory, experimental and computational results. Our theory is known, from its derivation, to be an approximation for particularly bouncy or ‘grippy’ surfaces where the die rolls through many revolutions before settling. On real surfaces we would expect (and we observe) that the true probability ratio for a 2D die is a somewhat closer to unity than predicted by our theory. This problem may also have wider relevance in the testing of physics engines.
Spectroscopic properties of multilayered gold nanoparticle 2D sheets.
Yoshida, Akihito; Imazu, Keisuke; Li, Xinheng; Okamoto, Koichi; Tamada, Kaoru
2012-12-11
We report the fabrication technique and optical properties of multilayered two-dimensional (2D) gold nanoparticle sheets ("Au nanosheet"). The 2D crystalline monolayer sheet composed of Au nanoparticles shows an absorption peak originating from a localized surface plasmon resonance (LSPR). It was found that the absorption spectra dramatically change when the monolayers are assembled into the multilayers on different substrates (quartz or Au). In the case of the multilayers on Au thin film (d = 200 nm), the LSPR peak is shifted to longer wavelength at the near-IR region by increasing the number of layers. The absorbance also depends on the layer number and shows the nonlinear behavior. On the other hand, the multilayers on quartz substrate show neither such LSPR peak shift nor nonlinear response of absorbance. The layer number dependence on metal surfaces can be interpreted as the combined effects between the near-field coupling of the LSPR and the far-field optics of the stratified metamaterial films, as proposed in our previous study. We also report the spectroscopic properties of hybrid multilayers composed of two kinds of monolayers, i.e., Au nanosheet and Ag nanosheet. The combination of the different metal nanoparticle sheets realizes more flexible plasmonic color tuning. PMID:23153010
2D kinematic signatures of boxy/peanut bulges
Iannuzzi, Francesca
2015-01-01
We study the imprints of boxy/peanut structures on the 2D line-of-sight kinematics of simulated disk galaxies. The models under study belong to a family with varying initial gas fraction and halo triaxiality, plus few other control runs with different structural parameters; the kinematic information was extracted using the Voronoi-binning technique and parametrised up to the fourth order of a Gauss-Hermite series. Building on a previous work for the long-slit case, we investigate the 2D kinematic behaviour in the edge-on projection as a function of the boxy/peanut strength and position angle; we find that for the strongest structures the highest moments show characteristic features away from the midplane in a range of position angles. We also discuss the masking effect of a classical bulge and the ambiguity in discriminating kinematically this spherically-symmetric component from a boxy/peanut bulge seen end-on. Regarding the face-on case, we extend existing results to encompass the effect of a second bucklin...
The unitary conformal field theory behind 2D Asymptotic Safety
Andreas Nink; Martin Reuter
2015-12-21
Being interested in the compatibility of Asymptotic Safety with Hilbert space positivity (unitarity), we consider a local truncation of the functional RG flow which describes quantum gravity in $d>2$ dimensions and construct its limit of exactly two dimensions. We find that in this limit the flow displays a nontrivial fixed point whose effective average action is a non-local functional of the metric. Its pure gravity sector is shown to correspond to a unitary conformal field theory with positive central charge $c=25$. Representing the fixed point CFT by a Liouville theory in the conformal gauge, we investigate its general properties and their implications for the Asymptotic Safety program. In particular, we discuss its field parametrization dependence and argue that there might exist more than one universality class of metric gravity theories in two dimensions. Furthermore, studying the gravitational dressing in 2D asymptotically safe gravity coupled to conformal matter we uncover a mechanism which leads to a complete quenching of the a priori expected Knizhnik-Polyakov-Zamolodchikov (KPZ) scaling. A possible connection of this prediction to Monte Carlo results obtained in the discrete approach to 2D quantum gravity based upon causal dynamical triangulations is mentioned. Similarities of the fixed point theory to, and differences from, non-critical string theory are also described. On the technical side, we provide a detailed analysis of an intriguing connection between the Einstein-Hilbert action in $d>2$ dimensions and Polyakov's induced gravity action in two dimensions.
Alignment of multimodality, 2D and 3D breast images
NASA Astrophysics Data System (ADS)
Grevera, George J.; Udupa, Jayaram K.
2003-05-01
In a larger effort, we are studying methods to improve the specificity of the diagnosis of breast cancer by combining the complementary information available from multiple imaging modalities. Merging information is important for a number of reasons. For example, contrast uptake curves are an indication of malignancy. The determination of anatomical locations in corresponding images from various modalities is necessary to ascertain the extent of regions of tissue. To facilitate this fusion, registration becomes necessary. We describe in this paper a framework in which 2D and 3D breast images from MRI, PET, Ultrasound, and Digital Mammography can be registered to facilitate this goal. Briefly, prior to image acquisition, an alignment grid is drawn on the breast skin. Modality-specific markers are then placed at the indicated grid points. Images are then acquired by a specific modality with the modality specific external markers in place causing the markers to appear in the images. This is the first study that we are aware of that has undertaken the difficult task of registering 2D and 3D images of such a highly deformable (the breast) across such a wide variety of modalities. This paper reports some very preliminary results from this project.
MAZE. Generates 2D Input for DYNA, NIKE & TOPAZ
Hallquist, J.O.
1992-02-12
MAZE is an interactive input generator for two-dimensional finite element codes. MAZE has three phases. In the first phase, lines and parts are defined. The first phase is terminated by the `ASSM` or `PASSM` command which merges all parts. In the second phase, boundary conditions may be specified, slidelines may be defined, parts may be merged to eliminate nodes along common interfaces, boundary nodes may be moved for graded zoning, the mesh may be smoothed, and load curves may be defined. The second phase is terminated by the `WBCD` command which causes MAZE to write the output file as soon as the `T` terminate command is typed. In the third phase, material properties may be defined. Commands that apply to the first phase may not be used in the second or third; likewise, commands that apply in the second may not be used in the first and third, or commands that apply in the third in the first and second. Nine commands - TV, Z, GSET, PLOTS, GRID, NOGRID, FRAME, NOFRAME, and RJET are available in all phases. Comments may be added anywhere in the input stream by prefacing the comment with `C`. Any DYNA2D or NIKE2D material and equation-of-state model may be defined via the MAT and EOS commands, respectively. MAZE may be terminated after phase two; it is not necessary to define the materials.
MAZE. Generates 2D Input for DYNA NIKE & TOPAZ
Hallquist, J.O.
1992-02-24
MAZE is an interactive input generator for two-dimensional finite element codes. MAZE has three phases. In the first phase, lines and parts are defined. The first phase is terminated by the `ASSM` or `PASSM` command which merges all parts. In the second phase, boundary conditions may be specified, slidelines may be defined, parts may be merged to eliminate nodes along common interfaces, boundary nodes may be moved for graded zoning, the mesh may be smoothed, and load curves may be defined. The second phase is terminated by the `WBCD` command which causes MAZE to write the output file as soon as the `T` terminate command is typed. In the third phase, material properties may be defined. Commands that apply to the first phase may not be used in the second or third; likewise, commands that apply in the second may not be used in the first and third, or commands that apply in the third in the first and second. Nine commands - TV, Z, GSET, PLOTS, GRID, NOGRID, FRAME, NOFRAME, and RJET are available in all phases. Comments may be added anywhere in the input stream by prefacing the comment with `C`. Any DYNA2D or NIKE2D material and equation-of-state model may be defined via the MAT and EOS commands, respectively. MAZE may be terminated after phase two; it is not necessary to define the materials.
MAZE. Generates 2D Input for DYNA NIKE & TOPAZ
Hallquist, J.O.
1992-02-10
MAZE is an interactive input generator for two-dimensional finite element codes. MAZE has three phases. In the first phase, lines and parts are defined. The first phase is terminated by the `ASSM` or `PASSM` command which merges all parts. In the second phase, boundary conditions may be specified, slidelines may be defined, parts may be merged to eliminate nodes along common interfaces, boundary nodes may be moved for graded zoning, the mesh may be smoothed, and load curves may be defined. The second phase is terminated by the `WBCD` command which causes MAZE to write the output file as soon as the `T` terminate command is typed. In the third phase, material properties may be defined. Commands that apply to the first phase may not be used in the second or third; likewise, commands that apply in the second may not be used in the first and third, or commands that apply in the third in the first and second. Nine commands - TV, Z, GSET, PLOTS, GRID, NOGRID, FRAME, NOFRAME, and RJET are available in all phases. Comments may be added anywhere in the input stream by prefacing the comment with `C`. Any DYNA2D or NIKE2D material and equation-of-state model may be defined via the MAT and EOS commands, respectively. MAZE may be terminated after phase two; it is not necessary to define the materials.
MAZE. Generates 2D Input for DYNA, NIKE, & TOPAZ
Hallquist, J.O.
1992-02-10
MAZE is an interactive input generator for two-dimensional finite element codes. MAZE has three phases. In the first phase, lines and parts are defined. The first phase is terminated by the `ASSM` or `PASSM` command which merges all parts. In the second phase, boundary conditions may be specified, slidelines may be defined, parts may be merged to eliminate nodes along common interfaces, boundary nodes may be moved for graded zoning, the mesh may be smoothed, and load curves may be defined. The second phase is terminated by the `WBCD` command which causes MAZE to write the output file as soon as the `T` terminate command is typed. In the third phase, material properties may be defined. Commands that apply to the first phase may not be used in the second or third; likewise, commands that apply in the second may not be used in the first and third, or commands that apply in the third in the first and second. Nine commands - TV, Z, GSET, PLOTS, GRID, NOGRID, FRAME, NOFRAME, and RJET are available in all phases. Comments may be added anywhere in the input stream by prefacing the comment with `C`. Any DYNA2D or NIKE2D material and equation-of-state model may be defined via the MAT and EOS commands, respectively. MAZE may be terminated after phase two; it is not necessary to define the materials.
New Approach for 2D Readout of GEM Detectors
Hasell, Douglas K
2011-10-29
Detectors based on Gas Electron Multiplication (GEM) technology are becoming more and more widely used in nuclear and high energy physics and are being applied in astronomy, medical physics, industry, and homeland security. GEM detectors are thin, low mass, insensitive to magnetic fields, and can currently provide position resolutions down to {approx}50 microns. However, the designs for reconstructing the position, in two dimensions (2D), of the charged particles striking a GEM detector are often complicated to fabricate and expensive. The objective of this proposal is to investigate a simpler procedure for producing the two dimensional readout layer of GEM detectors using readily available printed circuit board technology which can be tailored to the detector requirements. We will use the established GEM laboratory and facilities at M.I.T. currently employed in developing GEM detectors for the STAR forward tracking upgrade to simplify the testing and evaluation of the new 2D readout designs. If this new design proves successful it will benefit future nuclear and high energy physics experiments already being planned and will similarly extend and simplify the application of GEM technology to other branches of science, medicine, and industry. These benefits would be not only in lower costs for fabrication but also it increased flexibility for design and application.
Flatbands in 2D boroxine-linked covalent organic frameworks.
Wang, Rui-Ning; Zhang, Xin-Ran; Wang, Shu-Fang; Fu, Guang-Sheng; Wang, Jiang-Long
2015-12-23
Density functional calculations have been performed to analyze the electronic and mechanical properties of a number of 2D boroxine-linked covalent organic frameworks (COFs), which are experimentally fabricated from di-borate aromatic molecules. Furthermore, the band structures are surprising and show flat-band characteristics which are mainly attributed to the delocalized ?-conjugated electrons around the phenyl rings and can be better understood within aromaticity theories. Next, the effects of branch sizes and hydrostatic strains on their band structures are systematically considered within generalized gradient approximations. It is found that their band gaps will start to saturate when the branch size reaches 9. For boroxine-linked COFs with only one benzene ring in the branch, the band gap is robust under compressive strain while it decreases with the tensile strain increasing. When the branch size is equal or greater than 2, their band gaps will monotonously increase with the strain increasing in the range of [-1.0, 2.0] Å. All boroxine-linked COFs are semiconductors with controllable band gaps, depending on the branch length and the applied strain. In comparison with other 2D materials, such as graphene, hexagonal boron nitride, and even ?-graphyne, all boroxine-linked COFs are much softer and even more stable. That is, they can maintain the planar features under a larger compressive strain, which means that they are good candidates in flexible electronics. PMID:26662215
2D Gridded Surface Data Value-Added Product
Tang, Q; Xie, S
2015-08-30
This report describes the Atmospheric Radiation Measurement (ARM) Best Estimate (ARMBE) 2-dimensional (2D) gridded surface data (ARMBE2DGRID) value-added product. Spatial variability is critically important to many scientific studies, especially those that involve processes of great spatial variations at high temporal frequency (e.g., precipitation, clouds, radiation, etc.). High-density ARM sites deployed at the Southern Great Plains (SGP) allow us to observe the spatial patterns of variables of scientific interests. The upcoming megasite at SGP with its enhanced spatial density will facilitate the studies at even finer scales. Currently, however, data are reported only at individual site locations at different time resolutions for different datastreams. It is difficult for users to locate all the data they need and requires extra effort to synchronize the data. To address these problems, the ARMBE2DGRID value-added product merges key surface measurements at the ARM SGP sites and interpolates the data to a regular 2D grid to facilitate the data application.
Hamiltonian Operators of Dubrovin-Novikov Type in 2D
NASA Astrophysics Data System (ADS)
Ferapontov, Evgeny V.; Lorenzoni, Paolo; Savoldi, Andrea
2015-03-01
First order Hamiltonian operators of differential-geometric type were introduced by Dubrovin and Novikov in 1983, and thoroughly investigated by Mokhov. In 2D, they are generated by a pair of compatible flat metrics and which satisfy a set of additional constraints coming from the skew-symmetry condition and the Jacobi identity. We demonstrate that these constraints are equivalent to the requirement that is a linear Killing tensor of g with zero Nijenhuis torsion. This allowed us to obtain a complete classification of n-component operators with n ? 4 (for n = 1, 2 this was done before). For 2D operators the Darboux theorem does not hold: the operator may not be reducible to constant coefficient form. All interesting (non-constant) examples correspond to the case when the flat pencil is not semisimple, that is, the affinor has non-trivial Jordan block structure. In the case of a direct sum of Jordan blocks with distinct eigenvalues, we obtain a complete classification of Hamiltonian operators for any number of components n, revealing a remarkable correspondence with the class of trivial Frobenius manifolds modelled on H *( CP n-1).
Local currents in a 2D topological insulator
NASA Astrophysics Data System (ADS)
Dang, Xiaoqian; Burton, J. D.; Tsymbal, Evgeny Y.
2015-12-01
Symmetry protected edge states in 2D topological insulators are interesting both from the fundamental point of view as well as from the point of view of potential applications in nanoelectronics as perfectly conducting 1D channels and functional elements of circuits. Here using a simple tight-binding model and the Landauer-Büttiker formalism we explore local current distributions in a 2D topological insulator focusing on effects of non-magnetic impurities and vacancies as well as finite size effects. For an isolated edge state, we show that the local conductance decays into the bulk in an oscillatory fashion as explained by the complex band structure of the bulk topological insulator. We demonstrate that although the net conductance of the edge state is topologically protected, impurity scattering leads to intricate local current patterns. In the case of vacancies we observe vortex currents of certain chirality, originating from the scattering of current-carrying electrons into states localized at the edges of hollow regions. For finite size strips of a topological insulator we predict the formation of an oscillatory band gap in the spectrum of the edge states, the emergence of Friedel oscillations caused by an open channel for backscattering from an impurity and antiresonances in conductance when the Fermi energy matches the energy of the localized state created by an impurity.
Ramsey Spectroscopy Using a Tilted 2D MOT
NASA Astrophysics Data System (ADS)
Knutson, Erin; Simha, Raghav; Kwolek, Jonathan M.; Narducci, Frank A.
2015-05-01
We study Ramsey spectroscopy using a 2D tilted MOT. We use a tilted two-dimensional magneto-optical trap (2D MOT) to form a cold and continuous beam of Rubidium 85 atoms. The beam emerges from a pinhole where it passes through an on-resonance state preparation laser beam and then through a pair of co-propagating laser beams tuned to drive stimulated Raman transitions in the atoms. Finally, the beam passes through an on-resonance readout beam. We show that, by controlling the intensity of the Raman beams, we can make the product of the Rabi frequency and the transit time of the atoms through the laser beam equal to ? or ? / 2 as desired. We find a multi-peak Raman spectrum. We compare the width of the clock transition to the reciprocal of the atoms' transit time through the Raman fields. Finally, we study Ramsey spectroscopy using our system. Supported by a NavAir Section 219 grant.
SU-D-12A-04: Investigation of a 2D Antiscatter Grid for Flat Panel Detectors
Altunbas, C; Kavanagh, B; Miften, M; Zhong, Y; Shaw, C
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.
Brane Universe: Global Geometry
Berezin, Victor
2010-06-23
The global geometries of bulk vacuum space-times in the brane-universe models are investigated and classified in terms of geometrical invariants. The corresponding Carter-Penrose diagrams and embedding diagrams are constructed. It is shown that for a given energy-momentum induced on the brane there can be different types of global geometries depending on the signs of a bulk cosmological term and surface energy density of the brane (the sign of the latter does not influence the internal cosmological evolution). It is shown that in the Randall-Sundrum scenario it is possible to have an asymmetric hierarchy splitting even with a Z{sub 2}-symmetric matching of 'our' brane to the bulk.
Cylindrical geometry hall thruster
Raitses, Yevgeny (Princeton, NJ); Fisch, Nathaniel J. (Princeton, NJ)
2002-01-01
An apparatus and method for thrusting plasma, utilizing a Hall thruster with a cylindrical geometry, wherein ions are accelerated in substantially the axial direction. The apparatus is suitable for operation at low power. It employs small size thruster components, including a ceramic channel, with the center pole piece of the conventional annular design thruster eliminated or greatly reduced. Efficient operation is accomplished through magnetic fields with a substantial radial component. The propellant gas is ionized at an optimal location in the thruster. A further improvement is accomplished by segmented electrodes, which produce localized voltage drops within the thruster at optimally prescribed locations. The apparatus differs from a conventional Hall thruster, which has an annular geometry, not well suited to scaling to small size, because the small size for an annular design has a great deal of surface area relative to the volume.
NASA Astrophysics Data System (ADS)
Bergshoeff, Eric A.; Riccioni, Fabio
2011-08-01
We probe doubled geometry with dual fundamental branes, i.e. solitons. Restricting ourselves first to solitonic branes with more than two transverse directions we find that the doubled geometry requires an effective wrapping rule for the solitonic branes which is dual to the wrapping rule for fundamental branes. This dual wrapping rule can be understood by the presence of Kaluza-Klein monopoles. Extending our analysis to supersymmetric solitonic branes with less than or equal to two transverse directions we show that such solitons are precisely obtained by applying the same dual wrapping rule to these cases as well. This extended wrapping rule cannot be explained by the standard Kaluza-Klein monopole alone. Instead, it suggests the existence of a class of generalized Kaluza-Klein monopoles in ten-dimensional string theory.
Multilevel geometry optimization
Rodgers, Jocelyn M.; Fast, Patton L.; Truhlar, Donald G.
2000-02-15
Geometry optimization has been carried out for three test molecules using six multilevel electronic structure methods, in particular Gaussian-2, Gaussian-3, multicoefficient G2, multicoefficient G3, and two multicoefficient correlation methods based on correlation-consistent basis sets. In the Gaussian-2 and Gaussian-3 methods, various levels are added and subtracted with unit coefficients, whereas the multicoefficient Gaussian-x methods involve noninteger parameters as coefficients. The multilevel optimizations drop the average error in the geometry (averaged over the 18 cases) by a factor of about two when compared to the single most expensive component of a given multilevel calculation, and in all 18 cases the accuracy of the atomization energy for the three test molecules improves; with an average improvement of 16.7 kcal/mol. (c) 2000 American Institute of Physics.
Uehara, Shotaro; Uno, Yasuhiro; Hagihira, Yuya; Murayama, Norie; Shimizu, Makiko; Inoue, Takashi; Sasaki, Erika; Yamazaki, Hiroshi
2015-01-01
1.?Although the New World non-human primate, the common marmoset (Callithrix jacchus), is a potentially useful animal model, comprehensive understanding of drug metabolizing enzymes is insufficient. 2.?A cDNA encoding a novel cytochrome P450 (P450) 2D8 was identified in marmosets. The amino acid sequence deduced from P450 2D8 cDNA showed a high sequence identity (83-86%) with other primate P450 2Ds. Phylogenetic analysis showed that marmoset P450 2D8 was closely clustered with human P450 2D6, unlike P450 2Ds of miniature pig, dog, rabbit, guinea pig, mouse or rat. 3.?Marmoset P450 2D8 mRNA was predominantly expressed in the liver and small intestine among the tissues types analyzed, whereas marmoset P450 2D6 mRNA was expressed predominantly in the liver where P450 2D protein was detected by immunoblotting. 4.?By metabolic assays using marmoset P450 2D8 protein heterologously expressed in Escherichia coli, although P450 2D8 exhibits lower catalytic efficiency compared to marmoset and human P450 2D6 enzymes, P450 2D8 mediated O-demethylations of metoprolol and dextromethorphan and bufuralol 1'-hydroxylation. 5.?These results suggest that marmoset P450 2D8 (also expressed in the extrahepatic tissues) has potential roles in drug metabolism in a similar manner to those of human and marmoset P450 2D6. PMID:25801057
Wang, Danxin; Poi, Ming J.; Sun, Xiaochun; Gaedigk, Andrea; Leeder, J. Steven; Sadee, Wolfgang
2014-01-01
Cytochrome P450 2D6 (CYP2D6) is involved in the metabolism of 25% of clinically used drugs. Genetic polymorphisms cause substantial variation in CYP2D6 activity and serve as biomarkers guiding drug therapy. However, genotype–phenotype relationships remain ambiguous except for poor metabolizers carrying null alleles, suggesting the presence of yet unknown genetic variants. Searching for regulatory CYP2D6 polymorphisms, we find that a SNP defining the CYP2D6*2 allele, rs16947 [R296C, 17–60% minor allele frequency (MAF)], previously thought to convey normal activity, alters exon 6 splicing, thereby reducing CYP2D6 expression at least 2-fold. In addition, two completely linked SNPs (rs5758550/rs133333, MAF 13–42%) increase CYP2D6 transcription more than 2-fold, located in a distant downstream enhancer region (>100 kb) that interacts with the CYP2D6 promoter. In high linkage disequilibrium (LD) with each other, rs16947 and the enhancer SNPs form haplotypes that affect CYP2D6 enzyme activity in vivo. In a pediatric cohort of 164 individuals, rs16947 alone (minor haplotype frequency 28%) was associated with reduced CYP2D6 metabolic activity (measured as dextromethorphan/metabolite ratios), whereas rs5758550/rs133333 alone (frequency 3%) resulted in increased CYP2D6 activity, while haplotypes containing both rs16947 and rs5758550/rs133333 were similar to the wild-type. Other alleles used in biomarker panels carrying these variants such as CYP2D6*41 require re-evaluation of independent effects on CYP2D6 activity. The occurrence of two regulatory variants of high frequency and in high LD, residing on a long haplotype, highlights the importance of gene architecture, likely shaped by evolutionary selection pressures, in determining activity of encoded proteins. PMID:23985325
Accurate 3D reconstruction of complex blood vessel geometries from intravascular ultrasound
Subramanian, Kalpathi R.
Accurate 3D reconstruction of complex blood vessel geometries from intravascular ultrasound images from 2D intravascular ultrasound (IVUS) images. Biplane x-ray ¯uoroscopy is used to image the ultrasound catheter tip at a few key points along its path as the catheter is pulled through the blood vessel
Lebeck, Alvin R.
) type instructions to accelerate audio, video and 2D image processing, such as Intel MMX [15], Sun Ultra]: 1) database traversal, 2) geometry computation, and 3) rasterization. Display models representing graphics scenes are generally stored in a database that must be traversed (stage 1) to extract
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.
NASA Astrophysics Data System (ADS)
Hojman, Sergio A.; Gamboa, J.; Méndez, F.
2012-10-01
The inverse problem of calculus of variations and s-equivalence are re-examined by using results obtained from non-commutative geometry ideas. The role played by the structure of the modified Poisson brackets is discussed in a general context and it is argued that classical s-equivalent systems may be non-equivalent at the quantum mechanical level. This last fact is explicitly discussed comparing different approaches to deal with the Nair-Polychronakos oscillator.
NASA Astrophysics Data System (ADS)
Cederwall, Martin; Rosabal, J. A.
2015-07-01
We investigate exceptional generalised diffeomorphisms based on E 8(8) in a geometric setting. The transformations include gauge transformations for the dual gravity field. The surprising key result, which allows for a development of a tensor formalism, is that it is possible to define field-dependent transformations containing connection, which are covariant. We solve for the spin connection and construct a curvature tensor. A geometry for the Ehlers symmetry SL( n + 1) is sketched. Some related issues are discussed.
Variation in the inhibitory potency of terbinafine among genetic variants of CYP2D6.
Akiyoshi, Takeshi; Ishiuchi, Miho; Imaoka, Ayuko; Ohtani, Hisakazu
2015-08-01
Cytochrome P450 2D6 (CYP2D6) is a highly polymorphic enzyme that is involved in the metabolism of many drugs. Terbinafine (TER) is a CYP2D6 inhibitor and causes persistent drug interactions in the clinical setting; however, its inhibitory mechanism and the differences in its inhibitory potency among genetic variants of CYP2D6 remain to be investigated. This study aimed to investigate the inhibitory mechanism of TER and the differences in its inhibitory potency among three CYP2D6 variants, CYP2D6.1, CYP2D6.2, and CYP2D6.10. In a competitive inhibition study, the metabolic activity of the CYP2D6 was assessed based on their demethylation of dextromethorphan in the presence or absence of TER, and the time-dependency of the inhibitory effects were examined by preincubating the enzymes with TER. TER had weaker inhibitory effects on CYP2D6.2 and CYP2D6.10 than on CYP2D6.1; i.e., TER exhibited Ki values (the concentration of inhibitor that results in half-maximal inhibition) of 0.0525, 0.355, and 1.85 ?M for CYP2D6.1, CYP2D6.2, and CYP2D6.10, respectively. The inhibitory effects of TER were not time-dependent. Since TER's Ki value for CYP2D6.10 was 35.2-fold higher than its Ki value for CYP2D6.1, the CYP2D6 genotype of subjects should be taken into account when estimating the severity of drug interactions involving TER. PMID:26195224
Super Cooled Large Droplet Analysis of Several Geometries Using LEWICE3D Version 3
NASA Technical Reports Server (NTRS)
Bidwell, Colin S.
2011-01-01
Super Cooled Large Droplet (SLD) collection efficiency calculations were performed for several geometries using the LEWICE3D Version 3 software. The computations were performed using the NASA Glenn Research Center SLD splashing model which has been incorporated into the LEWICE3D Version 3 software. Comparisons to experiment were made where available. The geometries included two straight wings, a swept 64A008 wing tip, two high lift geometries, and the generic commercial transport DLR-F4 wing body configuration. In general the LEWICE3D Version 3 computations compared well with the 2D LEWICE 3.2.2 results and with experimental data where available.
Emergent Complex Network Geometry
Wu, Zhihao; Menichetti, Giulia; Rahmede, Christoph; Bianconi, Ginestra
2015-01-01
Networks are mathematical structures that are universally used to describe a large variety of complex systems such as the brain or the Internet. Characterizing the geometrical properties of these networks has become increasingly relevant for routing problems, inference and data mining. In real growing networks, topological, structural and geometrical properties emerge spontaneously from their dynamical rules. Nevertheless we still miss a model in which networks develop an emergent complex geometry. Here we show that a single two parameter network model, the growing geometrical network, can generate complex network geometries with non-trivial distribution of curvatures, combining exponential growth and small-world properties with finite spectral dimensionality. In one limit, the non-equilibrium dynamical rules of these networks can generate scale-free networks with clustering and communities, in another limit planar random geometries with non-trivial modularity. Finally we find that these properties of the geometrical growing networks are present in a large set of real networks describing biological, social and technological systems. PMID:25985280
Integral geometry and holography
NASA Astrophysics Data System (ADS)
Czech, Bart?omiej; Lamprou, Lampros; McCandlish, Samuel; Sully, James
2015-10-01
We present a mathematical framework which underlies the connection between information theory and the bulk spacetime in the AdS3/CFT2 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 AdS3 whose kinematic space is two-dimensional de Sitter space.
Integral geometry and holography
Czech, Bartlomiej; Lamprou, Lampros; McCandlish, Samuel; Sully, James
2015-10-27
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.
Emergent Complex Network Geometry
NASA Astrophysics Data System (ADS)
Wu, Zhihao; Menichetti, Giulia; Rahmede, Christoph; Bianconi, Ginestra
2015-05-01
Networks are mathematical structures that are universally used to describe a large variety of complex systems such as the brain or the Internet. Characterizing the geometrical properties of these networks has become increasingly relevant for routing problems, inference and data mining. In real growing networks, topological, structural and geometrical properties emerge spontaneously from their dynamical rules. Nevertheless we still miss a model in which networks develop an emergent complex geometry. Here we show that a single two parameter network model, the growing geometrical network, can generate complex network geometries with non-trivial distribution of curvatures, combining exponential growth and small-world properties with finite spectral dimensionality. In one limit, the non-equilibrium dynamical rules of these networks can generate scale-free networks with clustering and communities, in another limit planar random geometries with non-trivial modularity. Finally we find that these properties of the geometrical growing networks are present in a large set of real networks describing biological, social and technological systems.
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.
Computer-Aided Geometry Modeling
NASA Technical Reports Server (NTRS)
Shoosmith, J. N. (compiler); Fulton, R. E. (compiler)
1984-01-01
Techniques in computer-aided geometry modeling and their application are addressed. Mathematical modeling, solid geometry models, management of geometric data, development of geometry standards, and interactive and graphic procedures are discussed. The applications include aeronautical and aerospace structures design, fluid flow modeling, and gas turbine design.
Graded geometry and Poisson reduction
Cattaneo, A. S.; Zambon, M.
2009-02-02
The main result extends the Marsden-Ratiu reduction theorem in Poisson geometry, and is proven by means of graded geometry. In this note we provide the background material about graded geometry necessary for the proof. Further, we provide an alternative algebraic proof for the main result.
Interactive initialization of 2D/3D rigid registration
Gong, Ren Hui; Güler, Özgür; Kürklüoglu, Mustafa; Lovejoy, John; Yaniv, Ziv
2013-12-15
Purpose: Registration is one of the key technical components in an image-guided navigation system. A large number of 2D/3D registration algorithms have been previously proposed, but have not been able to transition into clinical practice. The authors identify the primary reason for the lack of adoption with the prerequisite for a sufficiently accurate initial transformation, mean target registration error of about 10 mm or less. In this paper, the authors present two interactive initialization approaches that provide the desired accuracy for x-ray/MR and x-ray/CT registration in the operating room setting. Methods: The authors have developed two interactive registration methods based on visual alignment of a preoperative image, MR, or CT to intraoperative x-rays. In the first approach, the operator uses a gesture based interface to align a volume rendering of the preoperative image to multiple x-rays. The second approach uses a tracked tool available as part of a navigation system. Preoperatively, a virtual replica of the tool is positioned next to the anatomical structures visible in the volumetric data. Intraoperatively, the physical tool is positioned in a similar manner and subsequently used to align a volume rendering to the x-ray images using an augmented reality (AR) approach. Both methods were assessed using three publicly available reference data sets for 2D/3D registration evaluation. Results: In the authors' experiments, the authors show that for x-ray/MR registration, the gesture based method resulted in a mean target registration error (mTRE) of 9.3 ± 5.0 mm with an average interaction time of 146.3 ± 73.0 s, and the AR-based method had mTREs of 7.2 ± 3.2 mm with interaction times of 44 ± 32 s. For x-ray/CT registration, the gesture based method resulted in a mTRE of 7.4 ± 5.0 mm with an average interaction time of 132.1 ± 66.4 s, and the AR-based method had mTREs of 8.3 ± 5.0 mm with interaction times of 58 ± 52 s. Conclusions: Based on the authors' evaluation, the authors conclude that the registration approaches are sufficiently accurate for initializing 2D/3D registration in the OR setting, both when a tracking system is not in use (gesture based approach), and when a tracking system is already in use (AR based approach)
PRONTO 2D: A two-dimensional transient solid dynamics program
Taylor, L.M.; Flanagan, D.P.
1987-03-01
PRONTO 2D is a two-dimensional transient solid dynamics code for analyzing large deformations of highly nonlinear materials subjected to extremely high strain rates. This Lagrangian finite element program uses an explicit time integration operator to integrate the equations of motion. Four node uniform strain quadrilateral elements are used in the finite element formulation. A number of new numerical algorithms which have been developed for the code are described in this report. An adaptive time step control algorithm is described which greatly improves stability as well as performance in plasticity problems. A robust hourglass control scheme which eliminates hourglass distortions without disturbing the finite element solution is included. All constitutive models in PRONTO are cast in an unrotated configuration defined using the rotation determined from the polar decomposition of the deformation gradient. An accurate incremental algorithm was developed to determine this rotation and is described in detail. A robust contact algorithm was developed which allows for the impact and interaction of deforming contact surfaces of quite general geometry. A number of numerical examples are presented to demonstrate the utility of these algorithms. 41 refs., 51 figs., 5 tabs.
Enhancement of low-energy electron emission in 2D radioactive films.
Pronschinske, Alex; Pedevilla, Philipp; Murphy, Colin J; Lewis, Emily A; Lucci, Felicia R; Brown, Garth; Pappas, George; Michaelides, Angelos; Sykes, E Charles H
2015-09-01
High-energy radiation has been used for decades; however, the role of low-energy electrons created during irradiation has only recently begun to be appreciated. Low-energy electrons are the most important component of radiation damage in biological environments because they have subcellular ranges, interact destructively with chemical bonds, and are the most abundant product of ionizing particles in tissue. However, methods for generating them locally without external stimulation do not exist. Here, we synthesize one-atom-thick films of the radioactive isotope (125)I on gold that are stable under ambient conditions. Scanning tunnelling microscopy, supported by electronic structure simulations, allows us to directly observe nuclear transmutation of individual (125)I atoms into (125)Te, and explain the surprising stability of the 2D film as it underwent radioactive decay. The metal interface geometry induces a 600% amplification of low-energy electron emission (<10 eV; ref. ) compared with atomic (125)I. This enhancement of biologically active low-energy electrons might offer a new direction for highly targeted nanoparticle therapies. PMID:26076306
Fourier based methodology for simulating 2D-random shapes in heterogeneous materials
NASA Astrophysics Data System (ADS)
Mattrand, C.; Béakou, A.; Charlet, K.
2015-08-01
Gaining insights into the effects of microstructural details on materials behavior may be achieved by incorporating their attributes into numerical modeling. This requires us to make considerable efforts to feature heterogeneity morphology distributions and their spatial arrangement. This paper focuses on modeling the scatter observed in materials heterogeneity geometry. The proposed strategy is based on the development of a 1D-shape signature function representing the 2D-section of a given shape, on Fourier basis functions. The Fourier coefficients are then considered as random variables. This methodology has been applied to flax fibers which are gradually introduced into composite materials as a potential alternative to synthetic reinforcements. In this contribution, the influence of some underlying assumptions regarding the choice of one 1D-shape signature function, its discretization scheme and truncation level, and the best way of modeling the associated random variables is also investigated. Some configurations coming from the combination of these tuning parameters are found to be sufficiently relevant to render efficiently the morphometric factors of the observed fibers statistically speaking.
2-D Circulation Control Airfoil Benchmark Experiments Intended for CFD Code Validation
NASA Technical Reports Server (NTRS)
Englar, Robert J.; Jones, Gregory S.; Allan, Brian G.; Lin, Johb C.
2009-01-01
A current NASA Research Announcement (NRA) project being conducted by Georgia Tech Research Institute (GTRI) personnel and NASA collaborators includes the development of Circulation Control (CC) blown airfoils to improve subsonic aircraft high-lift and cruise performance. The emphasis of this program is the development of CC active flow control concepts for both high-lift augmentation, drag control, and cruise efficiency. A collaboration in this project includes work by NASA research engineers, whereas CFD validation and flow physics experimental research are part of NASA s systematic approach to developing design and optimization tools for CC applications to fixed-wing aircraft. The design space for CESTOL type aircraft is focusing on geometries that depend on advanced flow control technologies that include Circulation Control aerodynamics. The ability to consistently predict advanced aircraft performance requires improvements in design tools to include these advanced concepts. Validation of these tools will be based on experimental methods applied to complex flows that go beyond conventional aircraft modeling techniques. This paper focuses on recent/ongoing benchmark high-lift experiments and CFD efforts intended to provide 2-D CFD validation data sets related to NASA s Cruise Efficient Short Take Off and Landing (CESTOL) study. Both the experimental data and related CFD predictions are discussed.
Development of a self-packaged 2D MEMS thermal wind sensor for low power applications
NASA Astrophysics Data System (ADS)
Zhu, Yan-qing; Chen, Bei; Qin, Ming; Huang, Jian-qiu; Huang, Qing-an
2015-08-01
This article describes the design, fabrication, and testing of a self-packaged 2D thermal wind sensor. The sensor consists of four heaters and nine thermistors. A central thermistor senses the average heater temperature, whereas the other eight, which are distributed symmetrically around the heaters, measure the temperature differences between the upstream and downstream surface of the sensor. The sensor was realized on one side of a silicon-in-glass (SIG) substrate. Vertical silicon vias in the substrate ensure good thermal contact between the sensor and the airflow and the glass effectively isolates the heaters from the thermistors. The substrate was fabricated by using a glass reflow process, after which the sensor was realized by a lift-off process. The sensor’s geometry was investigated with the help of simulations. These show that narrow heaters, moderate heater spacing, and thin substrates all improve the sensor’s sensitivity. Finally, the sensor was tested and calibrated in a wind tunnel by using a linear interpolation algorithm. At a constant heating power of 24.5?mW, measurement results show that the sensor can detect airflow speeds of up to 25?m?s-1, with an accuracy of 0.1?m?s-1 at low speeds and 0.5?m?s-1 at high speeds. Airflow direction can be determined in a range of 360° with an accuracy of ±6°.
Enhancement of low-energy electron emission in 2D radioactive films
NASA Astrophysics Data System (ADS)
Pronschinske, Alex; Pedevilla, Philipp; Murphy, Colin J.; Lewis, Emily A.; Lucci, Felicia R.; Brown, Garth; Pappas, George; Michaelides, Angelos; Sykes, E. Charles H.
2015-09-01
High-energy radiation has been used for decades; however, the role of low-energy electrons created during irradiation has only recently begun to be appreciated. Low-energy electrons are the most important component of radiation damage in biological environments because they have subcellular ranges, interact destructively with chemical bonds, and are the most abundant product of ionizing particles in tissue. However, methods for generating them locally without external stimulation do not exist. Here, we synthesize one-atom-thick films of the radioactive isotope 125I on gold that are stable under ambient conditions. Scanning tunnelling microscopy, supported by electronic structure simulations, allows us to directly observe nuclear transmutation of individual 125I atoms into 125Te, and explain the surprising stability of the 2D film as it underwent radioactive decay. The metal interface geometry induces a 600% amplification of low-energy electron emission (<10 eV; ref. ) compared with atomic 125I. This enhancement of biologically active low-energy electrons might offer a new direction for highly targeted nanoparticle therapies.
Refractive effects on optical measurement of alveolar volume: a 2-D ray-tracing approach.
Golabchi, Fatemeh N; Brooks, Dana H; Gouldstone, Andrew; DiMarzio, Charles A
2011-01-01
Lung imaging and assessment of alveoli geometry in the lung tissue is of great importance. Optical coherence tomography (OCT) is a real-time imaging technique used for this purpose, based on near-infrared interferometry, that can image several layers of distal alveoli in the lung tissue. The OCT measurements use low coherence interferometry, where light reflections from surfaces in the tissue are used to construct 2D images of the tissue. OCT images provide better depth compared to other optical microscopy techniques such as confocal reflectance and two-photon microscopy. Therefore, it is important to detect and verify optical distortions that happens with OCT, including refractive effect at the tissue-air alveoli wall interface which is not taken into account in the OCT imaging model. In this paper, the refractive effect at the tissue-air interface of the alveoli wall is modeled using exact ray tracing and direct implementation of Snell's law, and differences between alveoli area computed from OCT imaging and those measured by exact ray tracing of the OCT signal are analyzed. PMID:22256140
Jelena Pesic; Xinliang Xu; Joseph Zsolt Terdik; Alejandro Lopez; Stuart A. Rice; Aaron R. Dinner; Norbert F. Scherer
2012-10-10
We investigate the response of a dense monodisperse quasi-two-dimensional (q2D) colloid suspension when a particle is dragged by a constant velocity optical trap. Consistent with microrheological studies of other geometries, the perturbation induces a leading density wave and trailing wake, and we use Stokesian Dynamics (SD) simulations to parse direct colloid-colloid and hydrodynamic interactions. We go on to analyze the underlying individual particle-particle collisions in the experimental images. The displacements of particles form chains reminiscent of stress propagation in sheared granular materials. From these data, we can reconstruct steady-state dipolar flow patterns that were predicted for dilute suspensions and previously observed in granular analogs to our system. The decay of this field differs, however, from point Stokeslet calculations, indicating that the finite size of the colloids is important. Moreover, there is a pronounced angular dependence that corresponds to the surrounding colloid structure, which evolves in response to the perturbation. Put together, our results show that the response of the complex fluid is highly anisotropic owing to the fact that the effects of the perturbation propagate through the structured medium via chains of colloid-colloid collisions.
What Can We Learn about Magnetotail Reconnection from 2D PIC Harris-Sheet Simulations?
NASA Astrophysics Data System (ADS)
Goldman, M. V.; Newman, D. L.; Lapenta, G.
2015-05-01
The Magnetosphere Multiscale Mission (MMS) will provide the first opportunity to probe electron-scale physics during magnetic reconnection in Earth's magnetopause and magnetotail. This article will address only tail reconnection—as a non-steady-state process in which the first reconnected field lines advance away from the x-point in flux pile-up fronts directed Earthward and anti-Earthward. An up-to-date microscopic physical picture of electron and ion-scale collisionless tail reconnection processes is presented based on 2-D Particle-In-Cell (PIC) simulations initiated from a Harris current sheet and on Cluster and Themis measurements of tail reconnection. The successes and limitations of simulations when compared to measured reconnection are addressed in detail. The main focus is on particle and field diffusion region signatures in the tail reconnection geometry. The interpretation of these signatures is vital to enable spacecraft to identify physically significant reconnection events, to trigger meaningful data transfer from MMS to Earth and to construct a useful overall physical picture of tail reconnection. New simulation results and theoretical interpretations are presented for energy transport of particles and fields, for the size and shape of electron and ion diffusion regions, for processes occurring near the fronts and for the {j} × {B} (Hall) electric field.
Self-alignment of silver nanoparticles in highly ordered 2D arrays
NASA Astrophysics Data System (ADS)
Rodríguez-León, Ericka; Íñiguez-Palomares, Ramón; Urrutia-Bañuelos, Efraín; Herrera-Urbina, Ronaldo; Tánori, Judith; Maldonado, Amir
2015-03-01
We have synthesized silver nanoparticles in the non-polar phase of non-aqueous microemulsions. The nanocrystals have been grown by reducing silver ions in the microemulsion cylindrical micelles formed by the reducing agent (ethylene glycol). By a careful deposit of the microemulsion phase on a substrate, the micelles align in a hexagonal geometry, thus forming a 2D array of parallel strings of individual silver nanoparticles on the substrate. The microemulsions are the ternary system of anionic surfactant, non-polar solvent (isooctane), and solvent polar (ethylene glycol); the size of synthesized nanoparticles is about 7 nm and they are monodisperse. The study of the microstructure was realized by transmission electron microscopy, high-resolution technique transmission electron microscopy (HR-TEM), and Fourier processing using the software Digital Micrograph for the determination of the crystalline structure of the HR-TEM images of the nanocrystals; chemical composition was determined using the energy-dispersive X-ray spectroscopy. Addition technique polarizing light microscopy allowed the observation of the hexagonal phase of the system. This method of synthesis and self-alignment could be useful for the preparation of patterned materials at the nanometer scale.
Digitally reconfigurable complex 2D Dual lattice structure by optical phase engineering
Kumar, Manish
2015-01-01
We present a method to combine two periodic lattice wave-fields to generate a complex dual lattice wave-field which could be employed for microfabrication of corresponding 2D dual lattice structures. Since the addition of two periodic lattice wave-fields is coherent in nature the resultant dual lattice structure is highly dependent on the relative phase difference between constituent wave-fields. We show that it is possible to have control over the dual lattice pattern by precisely controlling this relative phase difference. This control is enabled by making use of digitally addressable phase only spatial light modulator (SLM). We provide the computational method for calculation of corresponding phase mask to be displayed on the SLM and also verify the results experimentally by employing a simple 4f Fourier filter based geometry. The method is completely scalable and reconfigurable in terms of the choice of periodic lattice wave-fields and has the potential to form gradient phase masks which could be useful f...
2D numerical simulation of passive autocatalytic recombiner for hydrogen mitigation
NASA Astrophysics Data System (ADS)
Gera, B.; Sharma, P. K.; Singh, R. K.
2012-04-01
Resolving hydrogen related safety issues, pertaining to nuclear reactor safety has been an important area of research world over for the past decade. The studies on hydrogen transport behavior and development of hydrogen mitigation systems are still being pursued actively in various research labs, including Bhabha Atomic Research Centre (BARC), in India. The passive autocatalytic recombiner (PAR) is one of such hydrogen mitigating device consisting of catalyst surfaces arranged in an open-ended enclosure. In the plate type recombiner design sheets made of stainless steel and coated with platinum catalyst material are arranged in parallel inside a flow channel. The catalyst elements are exposed to a constant flow of a mixture of air, hydrogen and steam, a catalytic reaction occurs spontaneously at the catalyst surfaces and the heat of reaction produces natural convection flow through the enclosure. Numerical simulation and experiments are required for an in-depth knowledge of such plate type PAR. Specific finite volume based in-house 2D computational fluid dynamics (CFD) code has been developed to model and analyse the working of these recombiners and has been used to simulate one literature quoted experiment. The validation results were in good agreement against literature quoted German REKO experiments. Parametric study has been performed for particular recombiner geometry for various inlet conditions. Salient features of the simplified CFD model developed at BARC and results of the present model calculations are presented in this paper.
Photoacoustic imaging for deep targets in the breast using a multichannel 2D array transducer
NASA Astrophysics Data System (ADS)
Xie, Zhixing; Wang, Xueding; Morris, Richard F.; Padilla, Frederic R.; Lecarpentier, Gerald L.; Carson, Paul L.
2011-03-01
A photoacoustic (PA) imaging system was developed to achieve high sensitivity for the detection and characterization of vascular anomalies in the breast in the mammographic geometry. Signal detection from deep in the breast was achieved by a broadband 2D PVDF planar array that has a round shape with one side trimmed straight to improve fit near the chest wall. This array has 572 active elements and a -6dB bandwidth of 0.6-1.7 MHz. The low frequency enhances imaging depth and increases the size of vascular collections displayed without edge enhancement. The PA signals from all the elements go through low noise preamplifiers in the probe that are very close to the array elements for optimized noise control. Driven by 20 independent on-probe signal processing channels, imaging with both high sensitivity and good speed was achieved. To evaluate the imaging depth and the spatial resolution of this system,2.38mm I.D. artificial vessels embedded deeply in ex vivo breasts harvested from fresh cadavers and a 3mm I.D. tube in breast mimicking phantoms made of pork loin and fat tissues were imaged. Using near-infrared laser light with incident energy density within the ANSI safety limit, imaging depths of up to 49 mm in human breasts and 52 mm in phantoms were achieved. With a high power tunable laser working on multiple wavelengths, this system might contribute to 3D noninvasive imaging of morphological and physiological tissue features throughout the breast.
3D-2D registration in mobile radiographs: algorithm development and preliminary clinical evaluation
NASA Astrophysics Data System (ADS)
Otake, Yoshito; Wang, Adam S.; Uneri, Ali; Kleinszig, Gerhard; Vogt, Sebastian; Aygun, Nafi; Lo, Sheng-fu L.; Wolinsky, Jean-Paul; Gokaslan, Ziya L.; Siewerdsen, Jeffrey H.
2015-03-01
An image-based 3D-2D registration method is presented using radiographs acquired in the uncalibrated, unconstrained geometry of mobile radiography. The approach extends a previous method for six degree-of-freedom (DOF) registration in C-arm fluoroscopy (namely ‘LevelCheck’) to solve the 9-DOF estimate of geometry in which the position of the source and detector are unconstrained. The method was implemented using a gradient correlation similarity metric and stochastic derivative-free optimization on a GPU. Development and evaluation were conducted in three steps. First, simulation studies were performed that involved a CT scan of an anthropomorphic body phantom and 1000 randomly generated digitally reconstructed radiographs in posterior-anterior and lateral views. A median projection distance error (PDE) of 0.007?mm was achieved with 9-DOF registration compared to 0.767?mm for 6-DOF. Second, cadaver studies were conducted using mobile radiographs acquired in three anatomical regions (thorax, abdomen and pelvis) and three levels of source-detector distance (~800, ~1000 and ~1200?mm). The 9-DOF method achieved a median PDE of 0.49?mm (compared to 2.53?mm for the 6-DOF method) and demonstrated robustness in the unconstrained imaging geometry. Finally, a retrospective clinical study was conducted with intraoperative radiographs of the spine exhibiting real anatomical deformation and image content mismatch (e.g. interventional devices in the radiograph that were not in the CT), demonstrating a PDE = 1.1?mm for the 9-DOF approach. Average computation time was 48.5?s, involving 687?701 function evaluations on average, compared to 18.2?s for the 6-DOF method. Despite the greater computational load, the 9-DOF method may offer a valuable tool for target localization (e.g. decision support in level counting) as well as safety and quality assurance checks at the conclusion of a procedure (e.g. overlay of planning data on the radiograph for verification of the surgical product) in a manner consistent with natural surgical workflow.
3D–2D registration in mobile radiographs: algorithm development and preliminary clinical evaluation
Otake, Yoshito; Wang, Adam S; Uneri, Ali; Kleinszig, Gerhard; Vogt, Sebastian; Aygun, Nafi; Lo, Sheng-fu L; Wolinsky, Jean-Paul; Gokaslan, Ziya L; Siewerdsen, Jeffrey H
2015-01-01
An image-based 3D–2D registration method is presented using radiographs acquired in the uncalibrated, unconstrained geometry of mobile radiography. The approach extends a previous method for six degree-of-freedom (DOF) registration in C-arm fluoroscopy (namely ‘LevelCheck’) to solve the 9-DOF estimate of geometry in which the position of the source and detector are unconstrained. The method was implemented using a gradient correlation similarity metric and stochastic derivative-free optimization on a GPU. Development and evaluation were conducted in three steps. First, simulation studies were performed that involved a CT scan of an anthropomorphic body phantom and 1000 randomly generated digitally reconstructed radiographs in posterior–anterior and lateral views. A median projection distance error (PDE) of 0.007 mm was achieved with 9-DOF registration compared to 0.767 mm for 6-DOF. Second, cadaver studies were conducted using mobile radiographs acquired in three anatomical regions (thorax, abdomen and pelvis) and three levels of source-detector distance (~800, ~1000 and ~1200 mm). The 9-DOF method achieved a median PDE of 0.49 mm (compared to 2.53 mm for the 6-DOF method) and demonstrated robustness in the unconstrained imaging geometry. Finally, a retrospective clinical study was conducted with intraoperative radiographs of the spine exhibiting real anatomical deformation and image content mismatch (e.g. interventional devices in the radiograph that were not in the CT), demonstrating a PDE = 1.1 mm for the 9-DOF approach. Average computation time was 48.5 s, involving 687 701 function evaluations on average, compared to 18.2 s for the 6-DOF method. Despite the greater computational load, the 9-DOF method may offer a valuable tool for target localization (e.g. decision support in level counting) as well as safety and quality assurance checks at the conclusion of a procedure (e.g. overlay of planning data on the radiograph for verification of the surgical product) in a manner consistent with natural surgical workflow. PMID:25674851
2D quantum gravity at three loops: a counterterm investigation
Leduc, Laetitia
2015-01-01
We analyse the divergences of the three-loop partition function at fixed area in 2D quantum gravity. Considering the Liouville action in the Kahler formalism, we extract the coefficient of the leading divergence in $\\sim A\\Lambda^2 (\\ln A\\Lambda^2)^2$. This coefficient is non-vanishing. We discuss the counterterms one can and must add and compute their precise contribution to the partition function. This allows us to conclude that every local and non-local divergence in the partition function can be balanced by local counterterms, with the only exception of the maximally non-local divergence $(\\ln A\\Lambda^2)^3$. Yet, this latter is computed and does cancel between the different three-loop diagrams. Thus, requiring locality of the counterterms is enough to renormalize the partition function. Finally, the structure of the new counterterms strongly suggests that they can be understood as a renormalization of the measure action.
2D quantum gravity at three loops: a counterterm investigation
Laetitia Leduc; Adel Bilal
2015-04-07
We analyse the divergences of the three-loop partition function at fixed area in 2D quantum gravity. Considering the Liouville action in the Kahler formalism, we extract the coefficient of the leading divergence in $\\sim A\\Lambda^2 (\\ln A\\Lambda^2)^2$. This coefficient is non-vanishing. We discuss the counterterms one can and must add and compute their precise contribution to the partition function. This allows us to conclude that every local and non-local divergence in the partition function can be balanced by local counterterms, with the only exception of the maximally non-local divergence $(\\ln A\\Lambda^2)^3$. Yet, this latter is computed and does cancel between the different three-loop diagrams. Thus, requiring locality of the counterterms is enough to renormalize the partition function. Finally, the structure of the new counterterms strongly suggests that they can be understood as a renormalization of the measure action.
Coherent state, local excitation in 2D conformal field theory
Wu-Zhong Guo
2015-10-24
In this paper we discuss the topics concerning the local excitation and coherent state in 2D CFT. It is shown that the local excitation of primary operator can be taken as a coherent state of the global conformal group. We also discuss the entanglement property of such state. For rational CFT the entanglement entropy between the holomorphic and anti-holomorphic sector of the local excitation of some primary operator is related to the quantum dimension of the operator, consistent with previous approach, but by a differentmethod. We comment on the possible application of so-defined group coherent state in the holographic view. We also study the coherent state in the free massless boson field, their time evolution and entanglement property. We introduce the deformed local excitation and the entangled state constructed by them. It is shown the violation of Bell inequality for such entangled state.
Coherent state, local excitation in 2D conformal field theory
Guo, Wu-Zhong
2015-01-01
In this paper we discuss the topics concerning the local excitation and coherent state in 2D CFT. It is shown that the local excitation of primary operator can be taken as a coherent state of the global conformal group. We also discuss the entanglement property of such state. For rational CFT the entanglement entropy between the holomorphic and anti-holomorphic sector of the local excitation of some primary operator is related to the quantum dimension of the operator, consistent with previous approach, but by a differentmethod. We comment on the possible application of so-defined group coherent state in the holographic view. We also study the coherent state in the free massless boson field, their time evolution and entanglement property. We introduce the deformed local excitation and the entangled state constructed by them. It is shown the violation of Bell inequality for such entangled state.
Experimental identification of diffusive coupling using 2D NMR.
Song, Y-Q; Carneiro, G; Schwartz, L M; Johnson, D L
2014-12-01
Spin relaxation based nuclear magnetic resonance (NMR) methods have been used extensively to determine pore size distributions in a variety of materials. This approach is based on the assumption that each pore is in the fast diffusion limit but that diffusion between pores can be neglected. However, in complex materials these assumptions may be violated and the relaxation time distribution is not easily interpreted. We present a 2D NMR technique and an associated data analysis that allow us to work directly with the time dependent experimental data without Laplace inversion to identify the signature of diffusive coupling between different pores. Measurements on microporous glass beads and numerical simulations are used to illustrate the technique. PMID:25526135
TOPAZ2D validation status report, August 1990
Davis, B.
1990-08-01
Analytic solutions to two heat transfer problems were used to partially evaluate the performance TOPAZ, and LLNL finite element heat transfer code. The two benchmark analytic solutions were for: 2D steady state slab, with constant properties, constant uniform temperature boundary conditions on three sides, and constant temperature distribution according to a sine function on the fourth side; 1D transient non-linear, with temperature dependent conductivity and specific heat (varying such that the thermal diffusivity remained constant), constant heat flux on the front face and adiabatic conditions on the other face. The TOPAZ solution converged to the analytic solution in both the transient and the steady state problem. Consistent mass matrix type of analysis yielded best performance for the transient problem, in the late-time response; but notable unnatural anomalies were observed in the early-time temperature response at nodal locations near the front face. 5 refs., 22 figs.
A 2D channel-clogging biofilm model.
Winstanley, H F; Chapwanya, M; Fowler, A C; O'Brien, S B G
2015-09-01
We present a model of biofilm growth in a long channel where the biomass is assumed to have the rheology of a viscous polymer solution. We examine the competition between growth and erosion-like surface detachment due to the flow. A particular focus of our investigation is the effect of the biofilm growth on the fluid flow in the pores, and the issue of whether biomass can grow sufficiently to shut off fluid flow through the pores, thus clogging the pore space. Net biofilm growth is coupled along the pore length via flow rate and nutrient transport in the pore flow. Our 2D model extends existing results on stability of 1D steady state biofilm thicknesses to show that, in the case of flows driven by a fixed pressure drop, full clogging of the pore can indeed happen in certain cases dependent on the functional form of the detachment term. PMID:25240390
Effective Hamiltonians of 2D Spin Glass Clusters
NASA Astrophysics Data System (ADS)
Clement, Colin; Liarte, Danilo; Middleton, Alan; Sethna, James
2015-03-01
We have a method for directly identifying the clusters which are thought to dominate the dynamics of spin glasses. We also have a method for generating an effective Hamiltonian treating each cluster as an individual spin. We used these methods on a 2D Ising spin glass with Gaussian bonds. We study these systems by generating samples and correlation functions using a combination of Monte Carlo and high-performance numerically exact Pfaffian methods. With effective cluster Hamiltonians we can calculate the free energy asymmetry of the original clusters and perform a scaling analysis. The scaling exponents found are consistent with Domain-Wall Renormalization Group methods, and probe all length scales. We can also study the flow of these effective Hamiltonians by clustering the clustered spins, and we find that our hard spin Hamiltonians at high temperature retain accurate low-temperature fluctuations when compared to their parent models.
Hardware architecture for Fast 2D distance transformations
NASA Astrophysics Data System (ADS)
Giannakopoulou, Vasiliki; Masselos, Kostas
2014-04-01
Distance transformation algorithms approximations use distance transformation with small neighborhood pixels, defined by masks. There are many different DT approximations applied, and some of them are proposed to be implemented in custom hardware, exploiting the possibilities offered for accelerating the actions required in the proposed algorithm. In this paper, a custom hardware architecture is proposed in order to implement fast 2D distance transformations that are independent of the distance function used. The current implementation concerns the Euclidean distance transform and Kintex7 evaluation board is used for this purpose. Area and synthesis results are presented for various image sizes, while it is observed a speed increase of 98% against the X86 architecture.
Anatomy of high-performance 2D similarity calculations.
Haque, Imran S; Pande, Vijay S; Walters, W Patrick
2011-09-26
Similarity measures based on the comparison of dense bit vectors of two-dimensional chemical features are a dominant method in chemical informatics. For large-scale problems, including compound selection and machine learning, computing the intersection between two dense bit vectors is the overwhelming bottleneck. We describe efficient implementations of this primitive as well as example applications using features of modern CPUs that allow 20-40× performance increases relative to typical code. Specifically, we describe fast methods for population count on modern x86 processors and cache-efficient matrix traversal and leader clustering algorithms that alleviate memory bandwidth bottlenecks in similarity matrix construction and clustering. The speed of our 2D comparison primitives is within a small factor of that obtained on GPUs and does not require specialized hardware. PMID:21854053
Realization of Discrete Quantum Billiard in 2D Optical Lattices
Dmitry O. Krimer; Ramaz Khomeriki
2011-05-24
We propose the method for optical visualization of Bose-Hubbard model with two interacting bosons in the form of two-dimensional (2D) optical lattices consisting of optical waveguides, where the waveguides at the diagonal are characterized by different refractive index than others elsewhere, modeling the boson-boson interaction. We study the light intensity distribution function averaged over direction of propagation for both ordered and disordered cases, exploring sensitivity of the averaged picture with respect to the beam injection position. For our finite systems the resulting patterns reminiscent the ones set in billiards and therefore we introduce a definition of discrete quantum billiard discussing the possible relevance to its well established continuous counterpart.
1092 Channel 2-D Array Demultiplexer for Ultralarge Data Bandwidth
NASA Astrophysics Data System (ADS)
Chan, Trevor K.; Karp, Jason; Jiang, Rui; Alic, Nikola; Radic, Stojan; Marki, Christopher F.; Ford, Joseph E.
2007-03-01
We demonstrate 1 x 1092 channel wavelength demultiplexing with 50-GHz channel pitch and a 600-nm total bandwidth. Outputs from 1 x 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 surface normal device (i.e., microelectromechanical system switch or detector array). Supercontinuum source input from 1140 to 1750 nm produced a 28 x 39 spot array at the output plane. The insertion loss for light is coupled into a single mode fiber ranged from 7 to 18 dB with less than 10-dB loss in channels between 1300 and 1750 nm. Bit-error-rate measurements show a negligible 0.1-dB power penalty at 10 GB/s.
First investigation of a novel 2D position-sensitive
Bassignana, D; Jaramillo, R; Lozano, M; Munoz, F J; Pellegrini, G; Quirion, D; Vila, I
2012-01-01
This paper presents a first study of the performance of a novel 2D position-sensitive microstrip detector, where the resistive charge division method was implemented by replacing the metallic electrodes with resistive electrodes made of polycrystalline silicon. A characterization of two proof-of-concept prototypes with different values of the electrode resistivity was carried out using a pulsed Near Infra-Red laser. The experimental data were compared with the electrical simulation of the sensor equivalent circuit coupled to simple electronics readout circuits. The good agreement between experimental and simulation results establishes the soundness of resistive charge division method in silicon microstrip sensors and validates the developed simulation as a tool for the optimization of future sensor prototypes. Spatial resolution in the strip length direction depends on the ionizing event position. The average value obtained from the protype analysis is close to 1.2% of the strip length for a 6 MIP signal.
areaDetector: Software for 2-D Detectors in EPICS
Rivers, M.
2011-09-23
areaDetector is a new EPICS module designed to support 2-D detectors. It is modular C++ code that greatly simplifies the task of writing support for a new detector. It also supports plugins, which receive detector data from the driver and process it in some way. Existing plugins perform Region-Of-Interest extraction and analysis, file saving (in netCDF, HDF, TIFF and JPEG formats), color conversion, and export to EPICS records for image display in clients like ImageJ and IDL. Drivers have now been written for many of the detectors commonly used at synchrotron beamlines, including CCDs, pixel array and amorphous silicon detectors, and online image plates.
areaDetector: Software for 2-D Detectors in EPICS
Rivers, Mark L.
2010-06-23
areaDetector is a new EPICS module designed to support 2-D detectors. It is modular C++ code that greatly simplifies the task of writing support for a new detector. It also supports plugins, which receive detector data from the driver and process it in some way. Existing plugins perform Region-Of-Interest extraction and analysis, file saving (in netCDF, HDF, TIFF and JPEG formats), color conversion, and export to EPICS records for image display in clients like ImageJ and IDL. Drivers have now been written for many of the detectors commonly used at synchrotron beamlines, including CCDs, pixel array and amorphous silicon detectors, and online image plates.
Quantal Heating of 2D electrons in strong magnetic fields
NASA Astrophysics Data System (ADS)
Vitkalov, Sergey; Bykov, Alexey
2011-03-01
Usually heating of conducting electrons by dc electric field increases electron temperature and effects weakly the electron transport. In this report we show that the dc heating of 2D electrons with a quantized spectrum is very peculiar and violates strongly the Ohm's Law. The quantal heating establishes nontrivial electron distribution, which has the same broadening or an effective ``temperature'' as the unbiased system. The heating reduces significantly the dissipative electron transport, forcing the quantum conductors into a state with zero differential resistance (ZDR). Furthermore an apparent dc driven metal-insulator transition is found, which correlates with the transition into the ZDR state. This interesting correlation is unexpected and is not understood. Support: NSF DMR 0349049 and RFBR Projects No. 10-02-00285.
Line generated 2D grid for neutral atom trapping
NASA Astrophysics Data System (ADS)
Lichtman, Martin; Saffman, Mark
2015-05-01
A phase-insensitive light field is desirable for stably trapping neutral atoms for quantum computing. Techniques are presented for creating a rectilinear array of atom trapping sites using holographically shaped beams with a gaussian profile in one transverse dimension, and a top-hat line profile in the other transverse dimension. This line generated grid creates an inherently 2D trap array at the focal plane, so that a low-crosstalk addressable qubit register may be implemented. The light field is projected from only one direction, and is insensitive to phase fluctuations and to misalignment in 2 degrees of freedom. This technique creates traps with depth twice that of previous singly-projected designs. Preliminary results for an 81-site cesium qubit register are presented. Work supported by the IARPA MQCO program.
Glassy Dislocation Dynamics in 2-D Colloidal Dimer Crystals
Sharon J. Gerbode; Umang Agarwal; Desmond C. Ong; Chekesha M. Liddell; Fernando Escobedo; Itai Cohen
2010-08-11
Although glassy relaxation is typically associated with disorder, here we report on a new type of glassy dynamics relating to dislocations within 2-D crystals of colloidal dimers. Previous studies have demonstrated that dislocation motion in dimer crystals is restricted by certain particle orientations. Here, we drag an optically trapped particle through such dimer crystals, creating dislocations. We find a two-stage relaxation response where initially dislocations glide until encountering particles that cage their motion. Subsequent relaxation occurs logarithmically slowly through a second process where dislocations hop between caged configurations. Finally, in simulations of sheared dimer crystals, the dislocation mean squared displacement displays a caging plateau typical of glassy dynamics. Together, these results reveal a novel glassy system within a colloidal crystal.
Advecting Procedural Textures for 2D Flow Animation
NASA Technical Reports Server (NTRS)
Kao, David; Pang, Alex; Moran, Pat (Technical Monitor)
2001-01-01
This paper proposes the use of specially generated 3D procedural textures for visualizing steady state 2D flow fields. We use the flow field to advect and animate the texture over time. However, using standard texture advection techniques and arbitrary textures will introduce some undesirable effects such as: (a) expanding texture from a critical source point, (b) streaking pattern from the boundary of the flowfield, (c) crowding of advected textures near an attracting spiral or sink, and (d) absent or lack of textures in some regions of the flow. This paper proposes a number of strategies to solve these problems. We demonstrate how the technique works using both synthetic data and computational fluid dynamics data.
Electrical spin injection in 2D semiconductors and topological insulators
Golub, L. E.; Ivchenko, E. L.
2013-12-04
We have developed a theory of spin orientation by electric current in 2D semiconductors. It is shown that the spin depends on the relation between the energy and spin relaxation times and can vary by a factor of two for the limiting cases of fast and slow energy relaxation. For symmetrically-doped (110)-grown semiconductor quantum wells the effect of current-induced spin orientation is shown to exist due to random spatial variation of the Rashba spin-orbit splitting. We demonstrate that the spin depends strongly on the correlation length of this random spin-orbit field. We calculate the spin orientation degree in two-dimensional topological insulators. In high electric fields when the “streaming” regime is realized, the spin orientation degree weakly depends on the electric field and can reach values about 5%.
Formation of novel 2D polymer nanowebs via electrospinning
NASA Astrophysics Data System (ADS)
Ding, Bin; Li, Chunrong; Miyauchi, Yasuhiro; Kuwaki, Oriha; Shiratori, Seimei
2006-08-01
We have found a procedure for generating novel two-dimensional (2D) nanowebs in three-dimensional (3D) fibrous mats by optimization of various processing parameters during electrospinning. The electrospun fibres act as a support for the 'fishnet-like' nanowebs comprising interlinked one-dimensional (1D) nanowires. The average diameter of the nanowires contained in typical nanowebs is about one order of magnitude less than that of conventional electrospun fibres. The formation of the nanowebs of poly(acrylic acid) (PAA) and nylon-6 is considered to be due to the electrically forced fast phase separation of the charged droplets which move at high speed between the capillary tip and the collector. The formation, morphology and area density of the nanowebs in electrospun fibrous mats are strongly affected by the applied voltage, ambient relative humidity, kinds of solvents, solution concentration and distance between the capillary tip and the collector.
von Ahsen, Nicolas; Tzvetkov, Mladen; Karunajeewa, Harin A; Gomorrai, Servina; Ura, Alice; Brockmöller, Jürgen; Davis, Timothy M E; Mueller, Ivo; Ilett, Kenneth F; Oellerich, Michael
2010-01-01
Purpose: A high frequency of previously unknown CYP2D6 alleles have been reported in Oceania populations. Genetic and functional properties of these alleles remain unknown. Methods: We performed analyses of the genetic variability of CYP2D6 and CYP2C19 genes using AmpliChip genotyping in cohorts from two distinct Papua New Guinea (PNG) populations (Kunjingini, n=88; Alexishafen, n=84) focussing on the genetic characterisation of PNG-specific alleles by re-sequencing. Results: Previously unknown CYP2D6 alleles have population frequencies of 24% (Kunjingini) and 12% (Alexishafen). An allele similar to CYP2D6*1, but carrying the 1661G>C substitution, was the second most frequent CYP2D6 allele (20% Kunjingini and 10% Alexishafen population frequency). Sequencing suggests the CYP2D6* 1661G>C allele originated from a cross-over between CYP2D6*1 and *2 and thus is predicted to confer fully active CYP2D6 enzyme. Two additional predicted full activity alleles [1661G>C;4180G>C] and 31G>A were found in the Kunjingini cohort (frequencies 3 c/c and 1%, respectively) and a novel predicted reduced activity allele [100C>T;1039C>T] was found in the Alexishafen cohort (frequency 2%). A high frequency of ultra-rapid (15%) and notably low frequencies of intermediate and poor CYP2D6 metabolizers (<5%) and a high frequency of poor CYP2C19 metabolizers were observed in PNG. Both CYP2D6 and CYP2C19 showed heterozygote excess that may be explained by exogamy and recent introduction of alleles by migration that are yet to reach HWE in relatively isolated populations. Conclusion: The CYP2D6*1661 allele common in Oceania may be regarded as functionally equivalent to the full activity CYP2D6*1 allele. PMID:21532842
Snowflake classification using a 2D video-disdrometer
NASA Astrophysics Data System (ADS)
Berne, A.; Monhart, S.; Schneebeli, M.
2012-12-01
Snowflakes can be formed in a variety of shapes (needle, plate, column, dendrite or aggregate to name a few) depending on the environmental conditions (mainly temperature and humidity). The 2D video-disdrometer (2DVD hereafter) is able to provide 2D pictures of the falling hydrometeors from 2 perpendicular views. Such detailed information is relevant to study the microstructure of precipitation in general and of snowfall in particular. A first valuable step is the ability to classify the snowflakes (to compare with polarimetric classification for instance). The main objective of the present contribution is to propose an innovative approach based on supervised classification to assign 2DVD measurements (1-min resolution) to different snowflake classes. A large data set corresponding to 2 winter seasons and collected in the Swiss Alps is used. After careful filtering and rematching of the falling particles sampled by a 2DVD, the values of 12 descriptors (related to the respective distributions according to height, width and fall speed) are calculated at each (1-min) time step. A training set is then built by manually classifying 2DVD data, so that the algorithm can be "trained" to classify time steps as a function of the 12 descriptors. 5 classes have been defined: large-aggregate-like, aggregate-like, dendrite-like, graupel-like and small particles. The comparison of the manual and automatic classifications on a set of about 190 (1-min) time steps covering all the 5 classes shows the good quality and reliability of the proposed automatic classification approach. Future work will focus on the comparison between the classification derived from measurements collected by the 2DVD and a near-by polarimetric radar.
2D Quantum Mechanical Study of Nanoscale MOSFETs
NASA Technical Reports Server (NTRS)
Svizhenko, Alexei; Anantram, M. P.; Govindan, T. R.; Biegel, B.; Kwak, Dochan (Technical Monitor)
2000-01-01
With the onset of quantum confinement in the inversion layer in nanoscale MOSFETs, behavior of the resonant level inevitably determines all device characteristics. While most classical device simulators take quantization into account in some simplified manner, the important details of electrostatics are missing. Our work addresses this shortcoming and provides: (a) a framework to quantitatively explore device physics issues such as the source-drain and gate leakage currents, DIBL, and threshold voltage shift due to quantization, and b) a means of benchmarking quantum corrections to semiclassical models (such as density-gradient and quantum-corrected MEDICI). We have developed physical approximations and computer code capable of realistically simulating 2-D nanoscale transistors, using the non-equilibrium Green's function (NEGF) method. This is the most accurate full quantum model yet applied to 2-D device simulation. Open boundary conditions and oxide tunneling are treated on an equal footing. Electrons in the ellipsoids of the conduction band are treated within the anisotropic effective mass approximation. We present the results of our simulations of MIT 25, 50 and 90 nm "well-tempered" MOSFETs and compare them to those of classical and quantum corrected models. The important feature of quantum model is smaller slope of Id-Vg curve and consequently higher threshold voltage. Surprisingly, the self-consistent potential profile shows lower injection barrier in the channel in quantum case. These results are qualitatively consistent with ID Schroedinger-Poisson calculations. The effect of gate length on gate-oxide leakage and subthreshold current has been studied. The shorter gate length device has an order of magnitude smaller current at zero gate bias than the longer gate length device without a significant trade-off in on-current. This should be a device design consideration.
2D Quantum Transport Modeling in Nanoscale MOSFETs
NASA Technical Reports Server (NTRS)
Svizhenko, Alexei; Anantram, M. P.; Govindan, T. R.; Biegel, Bryan
2001-01-01
With the onset of quantum confinement in the inversion layer in nanoscale MOSFETs, behavior of the resonant level inevitably determines all device characteristics. While most classical device simulators take quantization into account in some simplified manner, the important details of electrostatics are missing. Our work addresses this shortcoming and provides: (a) a framework to quantitatively explore device physics issues such as the source-drain and gate leakage currents, DIBL, and threshold voltage shift due to quantization, and b) a means of benchmarking quantum corrections to semiclassical models (such as density- gradient and quantum-corrected MEDICI). We have developed physical approximations and computer code capable of realistically simulating 2-D nanoscale transistors, using the non-equilibrium Green's function (NEGF) method. This is the most accurate full quantum model yet applied to 2-D device simulation. Open boundary conditions, oxide tunneling and phase-breaking scattering are treated on equal footing. Electrons in the ellipsoids of the conduction band are treated within the anisotropic effective mass approximation. Quantum simulations are focused on MIT 25, 50 and 90 nm "well- tempered" MOSFETs and compared to classical and quantum corrected models. The important feature of quantum model is smaller slope of Id-Vg curve and consequently higher threshold voltage. These results are quantitatively consistent with I D Schroedinger-Poisson calculations. The effect of gate length on gate-oxide leakage and sub-threshold current has been studied. The shorter gate length device has an order of magnitude smaller current at zero gate bias than the longer gate length device without a significant trade-off in on-current. This should be a device design consideration.
2D kinematic signatures of boxy/peanut bulges
NASA Astrophysics Data System (ADS)
Iannuzzi, Francesca; Athanassoula, E.
2015-07-01
We study the imprints of boxy/peanut structures on the 2D line-of-sight kinematics of simulated disc galaxies. The models under study belong to a family with varying initial gas fraction and halo triaxiality, plus few other control runs with different structural parameters; the kinematic information was extracted using the Voronoi-binning technique and parametrized up to the fourth order of a Gauss-Hermite series. Building on a previous work for the long-slit case, we investigate the 2D kinematic behaviour in the edge-on projection as a function of the boxy/peanut strength and position angle; we find that for the strongest structures the highest moments show characteristic features away from the mid-plane in a range of position angles. We also discuss the masking effect of a classical bulge and the ambiguity in discriminating kinematically this spherically symmetric component from a boxy/peanut bulge seen end-on. Regarding the face-on case, we extend existing results to encompass the effect of a second buckling and find that this phenomenon spurs an additional set of even deeper minima in the fourth moment. Finally, we show how the results evolve when inclining the disc away from perfectly edge-on and face-on. The behaviour of stars born during the course of the simulations is discussed and confronted to that of the pre-existing disc. The general aim of our study is providing a handle to identify boxy/peanut structures and their properties in latest generation Integral Field Unit observations of nearby disc galaxies.
Intrinsic limitations of spin transport in 2D membranes
NASA Astrophysics Data System (ADS)
Song, Yang
2014-03-01
Two dimensional membranes have become the playground for both theorists and experimentalists due to their unique intrinsic properties emerged from simple lattice structures. They are the new focus of spintronic applications. Therefore, it is important that we have a clear view of the relaxation processes in spin transport, limited by their intrinsic and symmetry structures. In this talk, we present our findings by systematically applying group theory to the coupling of phonons and transport carriers in spin-dependent scattering. Scattering by phonon is amplified in 2D membranes due to its unique and populous flexural mode. Opposite spin coupling by one flexural phonon is allowed by symmetry, unlike the momentum scattering by higher-order two flexural phonons. Furthermore, we specifically discuss the ultrafast electron spin relaxation in single-layer transition metal dichalcogenides (SL-TMDs). The additional factor stems from the decoupling of tiny conduction band spin splitting and the large spin scattering constant. The former results from conduction band orbital orientation, while the latter comes from inter-band coupling and reflects the atomic SOC strength. We will present that the essential use of group theory (invariant quantities) elucidates various spin-dependent selection rules of electron/hole-phonon interaction, within and between all relevant band-valley edges. Multiple potential applications of the derived results can be explored in transport problems, such as the strain effects, spin Gunn effect, hot exciton dynamics, and the scattering angle and spin anisotropy dependence. We compare different 2D membranes (graphene, SL-TMD, silicene and germanene) from general consideration of the lattice and band-edge symmetries. This work is supported by NRI-NSF, NSF, and DTRA Contracts No. DMR-1124601, No. ECCS-1231570, and No. HDTRA1-13-1-0013, respectively.
Helical Quantum Edge Gears in 2D Topological Insulators.
Chou, Yang-Zhi; Levchenko, Alex; Foster, Matthew S
2015-10-30
We show that two-terminal transport can measure the Luttinger liquid (LL) parameter K, in helical LLs at the edges of two-dimensional topological insulators (TIs) with Rashba spin-orbit coupling. We consider a Coulomb drag geometry with two coplanar TIs and short-ranged spin-flip interedge scattering. Current injected into one edge loop induces circulation in the second, which floats without leads. In the low-temperature (T?0) perfect drag regime, the conductance is (e^{2}/h)(2K+1)/(K+1). At higher T, we predict a conductivity ?T^{-4K+3}. The conductivity for a single edge is also computed. PMID:26565481
Helical Quantum Edge Gears in 2D Topological Insulators
NASA Astrophysics Data System (ADS)
Chou, Yang-Zhi; Levchenko, Alex; Foster, Matthew S.
2015-10-01
We show that two-terminal transport can measure the Luttinger liquid (LL) parameter K , in helical LLs at the edges of two-dimensional topological insulators (TIs) with Rashba spin-orbit coupling. We consider a Coulomb drag geometry with two coplanar TIs and short-ranged spin-flip interedge scattering. Current injected into one edge loop induces circulation in the second, which floats without leads. In the low-temperature (T ?0 ) perfect drag regime, the conductance is (e2/h )(2 K +1 )/(K +1 ). At higher T , we predict a conductivity ˜T-4 K +3. The conductivity for a single edge is also computed.
MORSE-CGA: a Monte Carlo radiation transport code with array geometry capability
Emmett, M.B.
1985-04-01
The MORSE-CG computer code system has been revised to add a new geometry module MARS, which is the combinatorial geometry package that allows multiple arrays for specifying geometries. The new code system is known as MORSE-CGA where CGA indicates Combinatorial Geometry Array. The PICTURE code, which makes printer plots of 2-D slices through a combinatorial geometry mock-up, has also been revised to handle the MARS array capability. This report will document the changes required in MORSE-CG and in PICTURE. Readers are referred to Sect. M9 of the SCALE document for details on MARS and to Sect. M13 of the SCALE document for details on PICTURE.
Probing 2D black phosphorus by quantum capacitance measurements
NASA Astrophysics Data System (ADS)
Kuiri, Manabendra; Kumar, Chandan; Chakraborty, Biswanath; Gupta, Satyendra N.; Naik, Mit H.; Jain, Manish; Sood, A. K.; Das, Anindya
2015-12-01
Two-dimensional materials and their heterostructures have emerged as a new class of materials, not only for fundamental physics but also for electronic and optoelectronic applications. Black phosphorus (BP) is a relatively new addition to this class of materials. Its strong in-plane anisotropy makes BP a unique material for making conceptually new types of electronic devices. However, the global density of states (DOS) of BP in device geometry has not been measured experimentally. Here, we report the quantum capacitance measurements together with the conductance measurements on an hBN-protected few-layer BP (?six layers) in a dual-gated field effect transistor (FET) geometry. The measured DOS from our quantum capacitance is compared with density functional theory (DFT). Our results reveal that the transport gap for quantum capacitance is smaller than that in conductance measurements due to the presence of localized states near the band edge. The presence of localized states is confirmed by the variable range hopping seen in our temperature dependence conductivity. A large asymmetry is observed between the electron and hole side. This asymmetric nature is attributed to the anisotropic band dispersion of BP. Our measurements establish the uniqueness of quantum capacitance in probing the localized states near the band edge, hitherto not seen in conductance measurements.
Probing 2D black phosphorus by quantum capacitance measurements.
Kuiri, Manabendra; Kumar, Chandan; Chakraborty, Biswanath; Gupta, Satyendra N; Naik, Mit H; Jain, Manish; Sood, A K; Das, Anindya
2015-12-01
Two-dimensional materials and their heterostructures have emerged as a new class of materials, not only for fundamental physics but also for electronic and optoelectronic applications. Black phosphorus (BP) is a relatively new addition to this class of materials. Its strong in-plane anisotropy makes BP a unique material for making conceptually new types of electronic devices. However, the global density of states (DOS) of BP in device geometry has not been measured experimentally. Here, we report the quantum capacitance measurements together with the conductance measurements on an hBN-protected few-layer BP (?six layers) in a dual-gated field effect transistor (FET) geometry. The measured DOS from our quantum capacitance is compared with density functional theory (DFT). Our results reveal that the transport gap for quantum capacitance is smaller than that in conductance measurements due to the presence of localized states near the band edge. The presence of localized states is confirmed by the variable range hopping seen in our temperature dependence conductivity. A large asymmetry is observed between the electron and hole side. This asymmetric nature is attributed to the anisotropic band dispersion of BP. Our measurements establish the uniqueness of quantum capacitance in probing the localized states near the band edge, hitherto not seen in conductance measurements. PMID:26559656
NASA Astrophysics Data System (ADS)
He, Yang-Hui; Jejjala, Vishnu; Matti, Cyril; Nelson, Brent D.; Stillman, Michael
2015-10-01
We present an intriguing and precise interplay between algebraic geometry and the phenomenology of generations of particles. Using the electroweak sector of the MSSM as a testing ground, we compute the moduli space of vacua as an algebraic variety for multiple generations of Standard Model matter and Higgs doublets. The space is shown to have Calabi-Yau, Grassmannian, and toric signatures, which sensitively depend on the number of generations of leptons, as well as inclusion of Majorana mass terms for right-handed neutrinos. We speculate as to why three generations is special.
Optically Defined Mechanical Geometry
Barasheed, Abeer Z; Sankey, Jack C
2015-01-01
In the field of optomechanics, radiation forces have provided a particularly high level of control over the frequency and dissipation of mechanical elements. Here we propose a class of optomechanical systems in which light exerts a profound influence over two other fundamental parameters: geometry and mass. By applying an optical trap to one lattice site of an extended phononic crystal, we show it is possible to create a tunable, localized mechanical mode. Owing to light's simultaneous and constructive coupling with the structure's continuum of modes, we estimate that a trap intensity at the level of a single photon should be capable of producing a measurable effect within a realistic, chip-scale device.
Kagan, Shelly
2005-01-01
Kansas The Geometry of Desert Shelly Kagan Here are two widely accepted claims about (moral) desert. First, people differ from one another in terms of how deserving they are, and because of this, some deserve more than others. Second, other things being equal..., it is an intrinsically good thing for people to get what they deserve. These two claims-which I will pretty much take as given in this paper-seem simple and straightforward enough. Of course, they imme diately bring us face to face with some familiar (and perennially...
Antenna-coupled microbolometer based uncooled 2D array and camera for 2D real-time terahertz imaging
NASA Astrophysics Data System (ADS)
Simoens, F.; Meilhan, J.; Gidon, S.; Lasfargues, G.; Lalanne Dera, J.; Ouvrier-Buffet, J. L.; Pocas, S.; Rabaud, W.; Guellec, F.; Dupont, B.; Martin, S.; Simon, A. C.
2013-09-01
CEA-Leti has developed a monolithic large focal plane array bolometric technology optimized for 2D real-time imaging in the terahertz range. Each pixel consists in a silicon microbolometer coupled to specific antennas and a resonant quarter-wavelength cavity. First prototypes of imaging arrays have been designed and manufactured for optimized sensing in the 1-3.5THz range where THz quantum cascade lasers are delivering high optical power. NEP in the order of 1 pW/sqrt(Hz) has been assessed at 2.5 THz. This paper reports the steps of this development, starting from the pixel level, to an array associated monolithically to its CMOS ROIC and finally a stand-alone camera. For each step, modeling, technological prototyping and experimental characterizations are presented.
40 CFR 721.10270 - [5,6]Fullerene-C84-D2d.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 2014-07-01 false [5,6]Fullerene-C84-D2d. 721.10270 Section...Substances § 721.10270 [5,6]Fullerene-C84-D2d. (a) Chemical substance...chemical substance identified as [5,6]Fullerene-C84-D2d (PMN...
40 CFR 721.10270 - [5,6]Fullerene-C84-D2d.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 2013-07-01 false [5,6]Fullerene-C84-D2d. 721.10270 Section...Substances § 721.10270 [5,6]Fullerene-C84-D2d. (a) Chemical substance...chemical substance identified as [5,6]Fullerene-C84-D2d (PMN...
Development of A 2-D Large Basin Operational Hydrologic Model Chansheng He
Development of A 2-D Large Basin Operational Hydrologic Model Chansheng He Department of Geography This paper reviews recent developments in hydrologic modeling, and through development of a 2-D large basin runoff model (2-D LBRM), discusses five essential components in the development of operational hydrologic
Fayer, Michael D.
with 2D IR Spectroscopy Oksana Kel, Amr Tamimi, Megan C. Thielges,# and Michael D. Fayer* Department (dilauroylphosphatidylcholine, DLPC) are investigated using 2D IR vibrational echo spectroscopy. The nonpolar and water of the membranes. The 2D IR experiments conducted on the antisymmetric CO stretching mode measure spectral
www.lphys.orgLASER Abstract: Ultrafast two dimensional infrared (2D-IR) vibra-
Fayer, Michael D.
www.lphys.orgLASER PHYSICS LETTERS REPRINT Abstract: Ultrafast two dimensional infrared (2D-IR- perimental details of 2D-IR vibrational echo spectroscopy in- cluding the experimental setup, pulse sequence, heterodyne de- tection, and extraction of the mainly absorptive part of the 2D- IR spectrum
Substrate binding and protein conformational dynamics measured by 2D-IR vibrational
Fayer, Michael D.
Substrate binding and protein conformational dynamics measured by 2D-IR vibrational echo of small organic molecule substrates is studied by using 2D-IR vibrational echo spectroscopy. Carbon? Ultrafast 2D-IR vibrational echo spectroscopy can probe protein conformational fluctuations under thermal
A GEOMETRIC ALGORITHM FOR FINDING THE MAXIMAL CUTTER FOR 2-D MILLING OPERATIONS
Nau, Dana S.
A GEOMETRIC ALGORITHM FOR FINDING THE MAXIMAL CUTTER FOR 2-D MILLING OPERATIONS Zhiyang Yao a geometric algorithm of finding the maximal cutter for 2-D milling operations. Our algorithm works not only for the common closed pocket problem, but also for the general 2-D milling problems with open edges. We define
FINDING THE MAXIMAL CUTTER FOR 2-D MILLING OPERATIONS Zhiyang Yao
Nau, Dana S.
FINDING THE MAXIMAL CUTTER FOR 2-D MILLING OPERATIONS Zhiyang Yao Mechanical Engineering Department feasible cutter size for 2-D milling operations to be performed using a single cutter. In particular: · We with an obstruction region. This definition encompasses the task of milling a general 2-D profile that includes both
Domain coarsening in 2D crystals B.Bak Saclay (F)
GyÃ¶rgy, GÃ©za
for higher temperature Disordered relaxed (equilibrium) configurations in the absence of climb Field theory preparation #12;May 18, 2010 Crystallization and Melting in 2D 3 Overview 2D lattices Mermin-Wagner: No infinite 2D lattice in equilibrium, if forces are short range small elastic constans, easy creation
A Third Order Central WENO Scheme for 2D Conservation Laws
Puppo, Gabriella
A Third Order Central WENO Scheme for 2D Conservation Laws Doron Levy y Gabriella Puppo z Giovanni laws in 2D. This scheme is based on the extension to 2D of the onedimensional Central WENO scheme we. The main idea is to use a convex combination of high order interpolating polynomials, as in the WENO
EXISTENCE OF GLOBAL WEAK SOLUTIONS FOR 2D SHALLOW WATER EQUATIONS WITH ITS DEGENERATE VISCOSITY
Vasseur, Alexis
EXISTENCE OF GLOBAL WEAK SOLUTIONS FOR 2D SHALLOW WATER EQUATIONS WITH ITS DEGENERATE VISCOSITY for 2D shallow water equations with degenerate viscosity. The method is based on the Bresch. Introduction The existence of global weak solutions of 2D shallow water equations with degenerate viscosity has
Illumination normalization using self-lighting ratios for 3D-2D face recognition
Kakadiaris, Ioannis
Illumination normalization using self-lighting ratios for 3D-2D face recognition Xi Zhao, Shishir K.com,shah@cs.uh.edu,ioannisk@uh.edu Abstract. 3D-2D face recognition is beginning to gain attention from the research community. It takes. In this paper, we present a novel illumination normalization approach for 3D-2D face recognition which does
Diffusion in confined geometries.
Burada, P Sekhar; Hänggi, Peter; Marchesoni, Fabio; Schmid, Gerhard; Talkner, Peter
2009-01-12
Diffusive transport of particles or, more generally, small objects, is a ubiquitous feature of physical and chemical reaction systems. In configurations containing confining walls or constrictions, transport is controlled both by the fluctuation statistics of the jittering objects and the phase space available to their dynamics. Consequently, the study of transport at the macro- and nanoscales must address both Brownian motion and entropic effects. Herein we report on recent advances in the theoretical and numerical investigation of stochastic transport occurring either in microsized geometries of varying cross sections or in narrow channels wherein the diffusing particles are hindered from passing each other (single-file diffusion). For particles undergoing biased diffusion in static suspension media enclosed by confining geometries, transport exhibits intriguing features such as 1) a decrease in nonlinear mobility with increasing temperature or also 2) a broad excess peak of the effective diffusion above the free diffusion limit. These paradoxical aspects can be understood in terms of entropic contributions resulting from the restricted dynamics in phase space. If, in addition, the suspension medium is subjected to external, time-dependent forcing, rectification or segregation of the diffusing Brownian particles becomes possible. Likewise, the diffusion in very narrow, spatially modulated channels is modified via contact particle-particle interactions, which induce anomalous sub-diffusion. The effective sub-diffusion constant for a driven single file also develops a resonance-like structure as a function of the confining coupling constant. PMID:19025741
Quasi 2D Materials: Raman Nanometrology and Thermal Management Applications
NASA Astrophysics Data System (ADS)
Shahil, Khan Mohammad Farhan
Quasi two-dimensional (2D) materials obtained by the "graphene-like" exfoliation attracted tremendous attention. Such materials revealed unique electronic, thermal and optical properties, which can be potentially used in electronics, thermal management and energy conversion. This dissertation research addresses two separate but synergetic problems: (i) preparation and optical characterization of quasi-2D films of the bismuth-telluride (Bi 2Te3) family of materials, which demonstrate both thermoelectric and topological insulator properties; and (ii) investigation of thermal properties of composite materials prepared with graphene and few-layer graphene (FLG). The first part of dissertation reports properties of the exfoliated few-quintuple layers of Bi2Te3, Bi2Se3 and Sb 2Te3. Both non-resonant and resonant Raman scattering spectra have been investigated. It was found that the crystal symmetry breaking in few-quintuple films results in appearance of A1u-symmetry Raman peaks, which are not active in the bulk crystals. The scattering spectra measured under the 633-nm wavelength excitation reveals a number of resonant features, which could be used for analysis of the electronic and phonon processes in these materials. The obtained results help to understand the physical mechanisms of Raman scattering in the few-quintuple-thick films and can be used for nanometrology of topological insulator films on various substrates. The second part of the dissertation is dedicated to investigation of properties of composite materials prepared with graphene and FLG. It was found that the optimized mixture of graphene and multilayer graphene---produced by the high-yield inexpensive liquid-phase-exfoliation technique---can lead to an extremely strong enhancement of the cross-plane thermal conductivity K of the composite. The "laser flash" measurements revealed a record-high enhancement of K by 2300 % in the graphene-based polymer at the filler loading fraction f =10 vol. %. It was determined that the relatively high concentration of the single-layer and bilayer graphene flakes (˜10--15%) present simultaneously with the thicker multilayers of large lateral size (˜ 1 microm) were essential for the observed unusual K enhancement. Our modeling results suggest that graphene-multilayer graphene nanocomposite used as the thermal interface material outperforms those with carbon nanotubes or metal nanoparticles owing to graphene's aspect ratio and lower Kapitza resistance at the graphene-matrix interface.
Pareto joint inversion of 2D magnetotelluric and gravity data
NASA Astrophysics Data System (ADS)
Miernik, Katarzyna; Bogacz, Adrian; Kozubal, Adam; Danek, Tomasz; Wojdy?a, Marek
2015-04-01
In this contribution, the first results of the "Innovative technology of petrophysical parameters estimation of geological media using joint inversion algorithms" project were described. At this stage of the development, Pareto joint inversion scheme for 2D MT and gravity data was used. Additionally, seismic data were provided to set some constrains for the inversion. Sharp Boundary Interface(SBI) approach and description model with set of polygons were used to limit the dimensionality of the solution space. The main engine was based on modified Particle Swarm Optimization(PSO). This algorithm was properly adapted to handle two or more target function at once. Additional algorithm was used to eliminate non- realistic solution proposals. Because PSO is a method of stochastic global optimization, it requires a lot of proposals to be evaluated to find a single Pareto solution and then compose a Pareto front. To optimize this stage parallel computing was used for both inversion engine and 2D MT forward solver. There are many advantages of proposed solution of joint inversion problems. First of all, Pareto scheme eliminates cumbersome rescaling of the target functions, that can highly affect the final solution. Secondly, the whole set of solution is created in one optimization run, providing a choice of the final solution. This choice can be based off qualitative data, that are usually very hard to be incorporated into the regular inversion schema. SBI parameterisation not only limits the problem of dimensionality, but also makes constraining of the solution easier. At this stage of work, decision to test the approach using MT and gravity data was made, because this combination is often used in practice. It is important to mention, that the general solution is not limited to this two methods and it is flexible enough to be used with more than two sources of data. Presented results were obtained for synthetic models, imitating real geological conditions, where interesting density distributions are relatively shallow and resistivity changes are related to deeper parts. This kind of conditions are well suited for joint inversion of MT and gravity data. In the next stage of the solution development of further code optimization and extensive tests for real data will be realized. Presented work was supported by Polish National Centre for Research and Development under the contract number POIG.01.04.00-12-279/13
Novel Raman instrumentation for characterizing 2D nanomaterials
NASA Astrophysics Data System (ADS)
Hight Walker, Angela
2015-03-01
We have designed and constructed a unique Raman microscope system to enable diffraction limited measurements of graphene and two-dimensional transition-metal dichalcogenides (TMD). The design enables low frequency phonon measurements down to ten wavenumbers through a triple grating Raman spectrometer, as well as resonance Raman spectroscopy through multiple laser excitation lines throughout the visible region. Through coupling to a cryogen-free magnet system, Raman spectra can be collected while the sample is in fields up 9 Tesla and at temperatures from 4 K to 400 K. Uniquely, both Farady and Voight geometries are accessible. Furthermore, multiple electronic feedthroughs permit collecting Raman scatter from devices at varying voltages. Proof of concept measurements on TMDs will highlight the full capabilities of the instrumentation. Collaborations are sought to demonstrate the utility of the new instrumentation.
Universal Entanglement Entropy in 2D Conformal Quantum Critical Points
Hsu, Benjamin; Mulligan, Michael; Fradkin, Eduardo; Kim, Eun-Ah
2008-12-05
We study the scaling behavior of the entanglement entropy of two dimensional conformal quantum critical systems, i.e. systems with scale invariant wave functions. They include two-dimensional generalized quantum dimer models on bipartite lattices and quantum loop models, as well as the quantum Lifshitz model and related gauge theories. We show that, under quite general conditions, the entanglement entropy of a large and simply connected sub-system of an infinite system with a smooth boundary has a universal finite contribution, as well as scale-invariant terms for special geometries. The universal finite contribution to the entanglement entropy is computable in terms of the properties of the conformal structure of the wave function of these quantum critical systems. The calculation of the universal term reduces to a problem in boundary conformal field theory.
NASA Astrophysics Data System (ADS)
Diot, S.; François, M. M.; Dendy, E. D.
2014-10-01
In this paper, we propose a non-iterative interface reconstruction method for 2D planar and axisymmetric geometries that is valid for arbitrary convex cells and intended to be used in multi-material simulation codes with sharp interface treatment for instance. Assuming that the normal vector to the interface is known, we focus on the computation of the line constant so that the polygon resulting from the cell-interface intersection has the requested volume. To this end, we first decompose the cell in trapezoidal elements and then propose a new approach to derive an exact formula for the trapezoids volumes. This formula, derived for both the planar and axisymmetric cases, is used to first bracket and then find the line constant that exactly matches the prescribed volume. The computational efficiency of the proposed method is demonstrated over a large number of reproducible conditions and against two existing methods.
Romero, V.J.; Ingber, M.S.
1995-07-01
A numerical model for simulating the transient nonlinear behavior of 2-D viscous sloshing flows in rectangular containers subjected to arbitrary horizontal accelerations is presented. The potential-flow formulation uses Rayleigh damping to approximate the effects of viscosity, and Lagrangian node movement is used to accommodate violent sloshing motions. A boundary element approach is used to efficiently handle the time-changing fluid geometry. Additionally, a corrected equation is presented for the constraint condition relating normal and tangential derivatives of the velocity potential where the fluid free surface meets the rigid container wall. The numerical model appears to be more accurate than previous sloshing models, as determined by comparison against exact analytic solutions and results of previously published models.
Improved 2D model of a ball bearing for the simulation of vibrations due to faults during run-up
NASA Astrophysics Data System (ADS)
Tadina, Matej; Boltežar, Miha
2011-07-01
This paper present an improved 2D bearing model for investigation of the vibrations of a ball-bearing during run-up. The presented numerical model assumes deformable outer race, which is modelled with finite elements, centrifugal load effects and radial clearance. The contact force for the balls is described by a nonlinear Hertzian contact deformation. Various surface defects due to local deformations are introduced into the developed model. The detailed geometry of the local defects is modelled as an impressed ellipsoid on the races and as a flattened sphere for the rolling balls. The obtained equations of motion were solved numerically with a modified Newmark time-integration method for the increasing rotational frequency of the shaft. The simulated vibrational response of the bearing with different local faults was used to test the suitability of the continuous wavelet transformation for the bearing fault identification and classification.
Non-universality in the 2D flocking model
NASA Astrophysics Data System (ADS)
Tarras, I.; Mazroui, M.; Moussa, N.; Boughaleb, Y.
2014-06-01
In this paper, we discuss the universality of the critical exponents ? and ? found in the Viscek model for one zone of interaction in the 2D flocking model. Within the framework of this model, the particles move with the same absolute velocity v0 and interact locally by trying to align their direction with that of neighbors. In this paper, we include a second zone of interaction named zone of repulsion R1, where each agent attempts to maintain a minimum distance from the others. Our model results show that in order to maintain an order in a flock with higher density, it is necessary to decrease the region of repulsion around each individual. Depending on the noise and on the density, the order parameter va is found to scale as ( (? c - ? )/(? c))? and ((? - ? c)/(?_c ))? , respectively. Our findings show that the exponents ? and ? depend strongly on the size of the repulsion zone and on the density ?, indicating the non-universality of these critical exponents. The analysis is performed over different situations by using a numerical simulation technique.
2D/3D registration algorithm for lung brachytherapy
Zvonarev, P. S.; Farrell, T. J.; Hunter, R.; Wierzbicki, M.; Hayward, J. E.; Sur, R. K.
2013-02-15
Purpose: A 2D/3D registration algorithm is proposed for registering orthogonal x-ray images with a diagnostic CT volume for high dose rate (HDR) lung brachytherapy. Methods: The algorithm utilizes a rigid registration model based on a pixel/voxel intensity matching approach. To achieve accurate registration, a robust similarity measure combining normalized mutual information, image gradient, and intensity difference was developed. The algorithm was validated using a simple body and anthropomorphic phantoms. Transfer catheters were placed inside the phantoms to simulate the unique image features observed during treatment. The algorithm sensitivity to various degrees of initial misregistration and to the presence of foreign objects, such as ECG leads, was evaluated. Results: The mean registration error was 2.2 and 1.9 mm for the simple body and anthropomorphic phantoms, respectively. The error was comparable to the interoperator catheter digitization error of 1.6 mm. Preliminary analysis of data acquired from four patients indicated a mean registration error of 4.2 mm. Conclusions: Results obtained using the proposed algorithm are clinically acceptable especially considering the complications normally encountered when imaging during lung HDR brachytherapy.
Flocking with discrete symmetry: the 2d Active Ising Model
A. P. Solon; J. Tailleur
2015-10-09
We study in detail the active Ising model, a stochastic lattice gas where collective motion emerges from the spontaneous breaking of a discrete symmetry. On a 2d lattice, active particles undergo a diffusion biased in one of two possible directions (left and right) and align ferromagnetically their direction of motion, hence yielding a minimal flocking model with discrete rotational symmetry. We show that the transition to collective motion amounts in this model to a bona fide liquid-gas phase transition in the canonical ensemble. The phase diagram in the density/velocity parameter plane has a critical point at zero velocity which belongs to the Ising universality class. In the density/temperature "canonical" ensemble, the usual critical point of the equilibrium liquid-gas transition is sent to infinite density because the different symmetries between liquid and gas phases preclude a supercritical region. We build a continuum theory which reproduces qualitatively the behavior of the microscopic model. In particular we predict analytically the shapes of the phase diagrams in the vicinity of the critical points, the binodal and spinodal densities at coexistence, and the speeds and shapes of the phase-separated profiles.
A 2D electrohydrodynamic model for electrorotation of fluid drops.
Feng, James Q
2002-02-01
A theoretical analysis of spontaneous electrorotation of deformable fluid drops in a DC electric field is presented with a 2D electrohydrodynamic model. The fluids in the system are assumed to be leaky dielectric and Newtonian. If the rotating flow is dominant over the cellular convection type of electrohydrodynamic flow, closed-form solutions for drops of small deformations can be obtained. Because the governing equations are in general nonlinear even when drop deformations are ignored, the general solution for even undeformed drop takes a form of infinite series and can only be evaluated by numerical means. Both closed-form solutions for special cases and numerical solutions for more general cases are obtained here to describe steady-state field variables and first-order drop deformations. In a DC electric field of strength beyond the threshold value, spontaneous electrorotation of a drop is shown to occur when charge relaxation in the surrounding fluid is faster than the fluid inside the drop. With increasing the strength of the applied electric field from the threshold for onset of electrorotation, the axis of drop contraction deviates from from that of the applied electric field in the direction of the rotating flow with an angle increasing with the field strength. PMID:16290391
Entanglement entropy for descendent local operators in 2D CFTs
NASA Astrophysics Data System (ADS)
Chen, Bin; Guo, Wu-Zhong; He, Song; Wu, Jie-qiang
2015-10-01
We mainly study the Rényi entropy and entanglement entropy of the states locally excited by the descendent operators in two dimensional conformal field theories (CFTs). In rational CFTs, we prove that the increase of entanglement entropy and Rényi entropy for a class of descendent operators, which are generated by {L}^{(-)}{overline{L}}^{(-)} onto the primary operator, always coincide with the logarithmic of quantum dimension of the corresponding primary operator. That means the Rényi entropy and entanglement entropy for these descendent operators are the same as the ones of their corresponding primary operator. For 2D rational CFTs with a boundary, we confirm that the Rényi entropy always coincides with the logarithmic of quantum dimension of the primary operator during some periods of the evolution. Furthermore, we consider more general descendent operators generated by {\\sum {d}_{{{n}_i}{{n}_j}}({{prod}_i{L}-{{}_n}{_i}{{prod}_j{{overline{L}}_{-n}}{_j}}})} on the primary operator. For these operators, the entanglement entropy and Rényi entropy get additional corrections, as the mixing of holomorphic and anti-holomorphic Virasoro generators enhance the entanglement. Finally, we employ perturbative CFT techniques to evaluate the Rényi entropy of the excited operators in deformed CFT. The Rényi and entanglement entropies are increased, and get contributions not only from local excited operators but also from global deformation of the theory.
Spotting 2D atomic layers on aluminum nitride thin films
NASA Astrophysics Data System (ADS)
Chandrasekar, Hareesh; Bharadwaj B, Krishna; Vaidyuala, Kranthi Kumar; Suran, Swathi; Bhat, Navakanta; Varma, Manoj; Raghavan, Srinivasan
2015-10-01
Substrates for 2D materials are important for tailoring their fundamental properties and realizing device applications. Aluminum nitride (AIN) films on silicon are promising large-area substrates for such devices in view of their high surface phonon energies and reasonably large dielectric constants. In this paper epitaxial layers of AlN on 2? Si wafers have been investigated as a necessary first step to realize devices from exfoliated or transferred atomic layers. Significant thickness dependent contrast enhancements are both predicted and observed for monolayers of graphene and MoS2 on AlN films as compared to the conventional SiO2 films on silicon, with calculated contrast values approaching 100% for graphene on AlN as compared to 8% for SiO2 at normal incidences. Quantitative estimates of experimentally measured contrast using reflectance spectroscopy show very good agreement with calculated values. Transistors of monolayer graphene on AlN films are demonstrated, indicating the feasibility of complete device fabrication on the identified layers.
Damage mechanics in 2-D and 3-D microstructures
NASA Astrophysics Data System (ADS)
Bowman, Keith J.; Ostoja-Starzewski, Martin
1993-02-01
The evolution of damage and strategies for assessing damage when it has occurred in structural materials is the primary focus of this research program. The research effort is a collaborative one on mesomechanics called 'Damage in 2D and 3D Microstructures.' What distinguishes this effort from others is the attempt to perform incisive model experiments to assist in evaluating stochastic models for constitutive laws (elasticity and conductivity), mechanical response plasticity, and hardness and associated damage processes. The theoretical models are designed to be elegant and efficient in the use of computing resources as opposed to brute force procedures which handle systems with different scales by scaling up the size of the computer. The essence of this work is to explore sample size microstructure relationships via stochastic models which reflect the same types of variability present in the response of real materials. This leads directly to concerns with effective properties of materials. Thus, research integrates the effects of microstructure and preferred orientation on the effective tensorial properties of polycrystalline materials.
2-D Modeling of Ring Cusp Ion Thruster Discharge Plasma
NASA Astrophysics Data System (ADS)
Wirz, Richie
2004-11-01
The computational validation of ion thruster life and performance is necessary for many proposed long-duration NASA missions. A 2-D model currently under development at JPL predicts the behavior of an axisymmetric ion thruster discharge chamber and is designed to interface with localized models that predict the wear of critical thruster components such as the discharge cathode and the ion extraction grids. The model uses an iterative scheme for predicting the steady-state operating point of the thruster by determining the non-uniform behavior of singly-charged ions, neutral atoms, primary electrons, and secondary electrons. Knowledge of the non-uniform densities of these plasma parameters within the discharge chamber is imperative to the accurate prediction of thruster component life. An important aspect of the model is the use of a computational mesh that is aligned with the magnetic field lines and magnetic potential contours to minimize numerical diffusion. The model is also capable of investigating scaling issues for extremely small and large ion thruster. The results of the model are validated using data from the NSTAR 30cm discharge.
Entanglement Entropy for Descendent Local Operators in 2D CFTs
Bin Chen; Wu-Zhong Guo; Song He; Jie-qiang Wu
2015-08-06
We mainly study the R\\'enyi entropy and entanglement entropy of the states locally excited by the descendent operators in two dimensional conformal field theories (CFTs). In rational CFTs, we prove that the increase of entanglement entropy and R\\'enyi entropy for a class of descendent operators, which are generated by $\\cal{L}^{(-)}\\bar{\\cal{L}}^{(-)}$ onto the primary operator, always coincide with the logarithmic of quantum dimension of the corresponding primary operator. That means the R\\'enyi entropy and entanglement entropy for these descendent operators are the same as the ones of their corresponding primary operator. For 2D rational CFTs with a boundary, we confirm that the R\\'enyi entropy always coincides with the logarithmic of quantum dimension of the primary operator during some periods of the evolution. Furthermore, we consider more general descendent operators generated by $\\sum_{} d_{\\{n_i\\}\\{n_j\\}}(\\prod_{i} L_{-n_i}\\prod_{j}{\\bar L}_{-n_j})$ on the primary operator. For these operators, the entanglement entropy and R\\'enyi entropy get additional corrections, as the mixing of holomorphic and anti-holomorphic Virasoro generators enhance the entanglement. Finally, we employ perturbative CFT techniques to evaluate the R\\'enyi entropy of the excited operators in deformed CFT. The R\\'enyi and entanglement entropies are increased, and get contributions not only from local excited operators but also from global deformation of the theory.
Spotting 2D atomic layers on aluminum nitride thin films.
Chandrasekar, Hareesh; Bharadwaj B, Krishna; Vaidyuala, Kranthi Kumar; Suran, Swathi; Bhat, Navakanta; Varma, Manoj; Srinivasan Raghavan
2015-10-23
Substrates for 2D materials are important for tailoring their fundamental properties and realizing device applications. Aluminum nitride (AIN) films on silicon are promising large-area substrates for such devices in view of their high surface phonon energies and reasonably large dielectric constants. In this paper epitaxial layers of AlN on 2? Si wafers have been investigated as a necessary first step to realize devices from exfoliated or transferred atomic layers. Significant thickness dependent contrast enhancements are both predicted and observed for monolayers of graphene and MoS2 on AlN films as compared to the conventional SiO2 films on silicon, with calculated contrast values approaching 100% for graphene on AlN as compared to 8% for SiO2 at normal incidences. Quantitative estimates of experimentally measured contrast using reflectance spectroscopy show very good agreement with calculated values. Transistors of monolayer graphene on AlN films are demonstrated, indicating the feasibility of complete device fabrication on the identified layers. PMID:26422387
Anatomy of luminosity functions: the 2dFGRS example
Elmo Tempel; Jaan Einasto; Maret Einasto; Enn Saar; Erik Tago
2008-10-15
Aims. We use the 2dF Galaxy Redshift Survey to derive the luminosity function (LF) of the first-ranked (brightest) group/cluster galaxies, the LF of second-ranked, satellite and isolated galaxies, and the LF of groups of galaxies. Methods. We investigate the LFs of different samples in various environments: in voids, filaments, superclusters and supercluster cores. We compare the derived LFs with the Schechter and double-power-law analytical expressions. We also analyze the luminosities of isolated galaxies. Results. We find strong environmental dependency of luminosity functions of all populations. The luminosities of first-ranked galaxies have a lower limit, depending on the global environment (higher in supercluster cores, and absent in voids). The LF of second-ranked galaxies in high-density regions is similar to the LF of first-ranked galaxies in a lower-density environment. The brightest isolated galaxies can be identified with first-ranked galaxies at distances where the remaining galaxies lie outside the observational window used in the survey. Conclusions. The galaxy and cluster LFs can be well approximated by a double-power-law; the widely used Schechter function does not describe well the bright end and the bend of the LFs. Properties of the LFs reflect differences in the evolution of galaxies and their groups in different environments.
Chemically engineered graphene-based 2D organic molecular magnet.
Hong, Jeongmin; Bekyarova, Elena; de Heer, Walt A; Haddon, Robert C; Khizroev, Sakhrat
2013-11-26
Carbon-based magnetic materials and structures of mesoscopic dimensions may offer unique opportunities for future nanomagnetoelectronic/spintronic devices. To achieve their potential, carbon nanosystems must have controllable magnetic properties. We demonstrate that nitrophenyl functionalized graphene can act as a room-temperature 2D magnet. We report a comprehensive study of low-temperature magnetotransport, vibrating sample magnetometry (VSM), and superconducting quantum interference (SQUID) measurements before and after radical functionalization. Following nitrophenyl (NP) functionalization, epitaxially grown graphene systems can become organic molecular magnets with ferromagnetic and antiferromagnetic ordering that persists at temperatures above 400 K. The field-dependent, surface magnetoelectric properties were studied using scanning probe microscopy (SPM) techniques. The results indicate that the NP-functionalization orientation and degree of coverage directly affect the magnetic properties of the graphene surface. In addition, graphene-based organic magnetic nanostructures were found to demonstrate a pronounced magneto-optical Kerr effect (MOKE). The results were consistent across different characterization techniques and indicate room-temperature magnetic ordering along preferred graphene orientations in the NP-functionalized samples. Chemically isolated graphene nanoribbons (CINs) were observed along the preferred functionality directions. These results pave the way for future magnetoelectronic/spintronic applications based on promising concepts such as current-induced magnetization switching, magnetoelectricity, half-metallicity, and quantum tunneling of magnetization. PMID:24156350
2D modeling of electromagnetic waves in cold plasmas
Crombé, K.; Van Eester, D.; Koch, R.; Kyrytsya, V.
2014-02-12
The consequences of sheath (rectified) electric fields, resulting from the different mobility of electrons and ions as a response to radio frequency (RF) fields, are a concern for RF antenna design as it can cause damage to antenna parts, limiters and other in-vessel components. As a first step to a more complete description, the usual cold plasma dielectric description has been adopted, and the density profile was assumed to be known as input. Ultimately, the relevant equations describing the wave-particle interaction both on the fast and slow timescale will need to be tackled but prior to doing so was felt as a necessity to get a feeling of the wave dynamics involved. Maxwell's equations are solved for a cold plasma in a 2D antenna box with strongly varying density profiles crossing also lower hybrid and ion-ion hybrid resonance layers. Numerical modelling quickly becomes demanding on computer power, since a fine grid spacing is required to capture the small wavelengths effects of strongly evanescent modes.
Photorealistic image synthesis and camera validation from 2D images
NASA Astrophysics Data System (ADS)
Santos Ferrer, Juan C.; González Chévere, David; Manian, Vidya
2014-06-01
This paper presents a new 3D scene reconstruction technique using the Unity 3D game engine. The method presented here allow us to reconstruct the shape of simple objects and more complex ones from multiple 2D images, including infrared and digital images from indoor scenes and only digital images from outdoor scenes and then add the reconstructed object to the simulated scene created in Unity 3D, these scenes are then validated with real world scenes. The method used different cameras settings and explores different properties in the reconstructions of the scenes including light, color, texture, shapes and different views. To achieve the highest possible resolution, it was necessary the extraction of partial textures from visible surfaces. To recover the 3D shapes and the depth of simple objects that can be represented by the geometric bodies, there geometric characteristics were used. To estimate the depth of more complex objects the triangulation method was used, for this the intrinsic and extrinsic parameters were calculated using geometric camera calibration. To implement the methods mentioned above the Matlab tool was used. The technique presented here also let's us to simulate small simple videos, by reconstructing a sequence of multiple scenes of the video separated by small margins of time. To measure the quality of the reconstructed images and video scenes the Fast Low Band Model (FLBM) metric from the Video Quality Measurement (VQM) software was used. Low bandwidth perception based features include edges and motion.
Global 2-D intercomparison of sectional and modal aerosol modules
Weisenstein, D. K.; Penner, J. E.; Herzog, M.; Liu, Xiaohong
2007-05-08
We present an intercomparison of two aerosol modules, one sectional, one modal, in a global 2-D model in order to differentiate their behavior for tropospheric and stratospheric applications. We model only binary sulfuric acid-water aerosols in this study. Two versions of the sec-tional model and three versions of the modal model are used to test the sensitivity of background aerosol mass and size distribution to the number of bins or modes and to the pre-scribed width of the largest mode. We ?nd modest sensitivity to the number of bins (40 vs 150) used in the sectional model. Aerosol mass is found to be reduced in a modal model if care is not taken in selecting the width of the largest lognormal mode, re?ecting differences in sedimentation in the middle stratosphere. The size distributions calculated by the sec-tional model can be better matched by a modal model with four modes rather than three modes in most but not all sit-uations. A simulation of aerosol decay following the 1991 eruption of Mt. Pinatubo shows that the representation of the size distribution can have a sign?cant impact on model-calculated aerosol decay rates in the stratosphere. Between 1991 and 1995, aerosol mass and surface area density calcu-lated by two versions of the modal model adequately match results from the sectional model. Calculated effective radius for the same time period shows more intermodel variability.
2-D stationary gas dynamics in a barred galaxy
NASA Astrophysics Data System (ADS)
Mulder, W. A.
2015-06-01
A code for solving the 2-D isothermal Euler equations of gas dynamics in a rotating disc is presented. The gravitational potential represents a weak bar and controls the flow. A damped Newton method solves the second-order upwind discretisation of the equations for a steady-state solution, using a consistent linearisation and a direct solver. Successive grid refinement, starting from a finite-volume grid with 8 by 8 cells, is applied to find solutions on subsequently finer meshes. On coarser meshes, a first-order spatial discretisation is used. The method obtains quadratic convergence once the solution approaches the steady state. The initial search is quick with the first-order scheme and slower with the second-order discretisation, up to 256 by 256 cells. Beyond, with 512 by 512 cells, the number of iterations becomes too large to be of practical use. Potential causes are discussed. The code can be applied as a tool for generating flow models if used on not too fine meshes.
2-D Model for Normal and Sickle Cell Blood Microcirculation
NASA Astrophysics Data System (ADS)
Tekleab, Yonatan; Harris, Wesley
2011-11-01
Sickle cell disease (SCD) is a genetic disorder that alters the red blood cell (RBC) structure and function such that hemoglobin (Hb) cannot effectively bind and release oxygen. Previous computational models have been designed to study the microcirculation for insight into blood disorders such as SCD. Our novel 2-D computational model represents a fast, time efficient method developed to analyze flow dynamics, O2 diffusion, and cell deformation in the microcirculation. The model uses a finite difference, Crank-Nicholson scheme to compute the flow and O2 concentration, and the level set computational method to advect the RBC membrane on a staggered grid. Several sets of initial and boundary conditions were tested. Simulation data indicate a few parameters to be significant in the perturbation of the blood flow and O2 concentration profiles. Specifically, the Hill coefficient, arterial O2 partial pressure, O2 partial pressure at 50% Hb saturation, and cell membrane stiffness are significant factors. Results were found to be consistent with those of Le Floch [2010] and Secomb [2006].
Development of 2-D focusing Multilayer Bragg-Fresnel Optics
NASA Astrophysics Data System (ADS)
Li, Youli; Yasa, Mario; Safinya, Cyrus; Caine, Ernie; Hu, Evelyn; Als-Nielsen, Jen; Freund, Andreas
2003-03-01
We developed a new 2-D focusing x-ray lens consisting of a linear thin film Fresnel zones fabricated on a multilayer mirror bent along the direction of the x-ray beam. This unique hybrid optic combines diffraction and geometric focusing elements in one single device and eliminates the need for a second mirror in conventional K-B mirror based x-ray microprobes. The linear Fresnel zones are made of a thin Au layer ( 15 nm) deposited on a 200-layer Si/Mo multilayer substrate after patterning by electron beam lithography. X-ray characterization of the prototype multilayer BFLs was conducted at beamline BM5 at the European Synchrotron Radiation Facility (ESRF) and the test lens provided a flux density gain of order 1000 with a 1.6 mm (vertical) x 10 mm focal spot. The vertical focus was limited by source demagnification whereas the horizontal focus was broadened by figure errors due to the simple bender used. We expect improvements in these areas to lead to submicron focusing in the near future. This combination multilayer Bragg-Fresnel is being used in x-ray microscopy and micro-diffraction studies of complex and biological materials. (Work supported by NSF-DMR-0076357, NSF-DMR-0203755 and ONR N00014-00-1-0214)
Fast VLSI architecture for 8 x 8 2D DCT
NASA Astrophysics Data System (ADS)
de Perthuis, Hughes; Bercovici, E.; de Grandmaison, A.; Akil, Mohamed
1995-04-01
Discrete Cosine Transform (DCT) is one of the most popular lossy techniques used today in video compression schemes. It allows to take advantage of the properties of natural images. Indeed thanks to their continuity for small surfaces (typically 8 X 8 pixels), they ask for a more compact description in the frequential plan than in the spatial one. A coupled quantization also brings further compression gain as it is now possible to degrade more the high frequencies of the image to which human eye is less sensitive. The drawback is that DCT puts heavy stress on computational resources and can be a bottleneck to cheap real time video. We here introduce a VLSI architecture which combines excellent performance with a small die size as we use an algorithm which maps very well on silicon. Through a reordering of the samples, regularity and complexity of the computations involved are greatly improved. This allows to divide the process into two parallel parts, one for even samples, the other for odd ones. As the number of coefficients required is decreased, fixed multipliers can be used. A simple join of the two parts' results followed by a normalization merged with quantization will give 8 X 8 2D DCT after a total of 64 cycles.
2D and 3D Chromosome Painting in Malaria Mosquitoes
George, Phillip; Sharma, Atashi; Sharakhov, Igor V
2014-01-01
Fluorescent in situ hybridization (FISH) of whole arm chromosome probes is a robust technique for mapping genomic regions of interest, detecting chromosomal rearrangements, and studying three-dimensional (3D) organization of chromosomes in the cell nucleus. The advent of laser capture microdissection (LCM) and whole genome amplification (WGA) allows obtaining large quantities of DNA from single cells. The increased sensitivity of WGA kits prompted us to develop chromosome paints and to use them for exploring chromosome organization and evolution in non-model organisms. Here, we present a simple method for isolating and amplifying the euchromatic segments of single polytene chromosome arms from ovarian nurse cells of the African malaria mosquito Anopheles gambiae. This procedure provides an efficient platform for obtaining chromosome paints, while reducing the overall risk of introducing foreign DNA to the sample. The use of WGA allows for several rounds of re-amplification, resulting in high quantities of DNA that can be utilized for multiple experiments, including 2D and 3D FISH. We demonstrated that the developed chromosome paints can be successfully used to establish the correspondence between euchromatic portions of polytene and mitotic chromosome arms in An. gambiae. Overall, the union of LCM and single-chromosome WGA provides an efficient tool for creating significant amounts of target DNA for future cytogenetic and genomic studies. PMID:24429496
Global small solutions of 2-D incompressible MHD system
NASA Astrophysics Data System (ADS)
Lin, Fanghua; Xu, Li; Zhang, Ping
2015-11-01
In this paper, we consider the global wellposedness of 2-D incompressible magneto-hydrodynamical system with smooth initial data which is close to some non-trivial steady state. It is a coupled system between the Navier-Stokes equations and a free transport equation with a universal nonlinear coupling structure. The main difficulty of the proof lies in exploring the dissipative mechanism of the system. To achieve this and to avoid the difficulty of propagating anisotropic regularity for the free transport equation, we first reformulate our system (1.1) in the Lagrangian coordinates (2.19). Then we employ anisotropic Littlewood-Paley analysis to establish the key a prioriL1 (R+ ; Lip (R2)) estimate for the Lagrangian velocity field Yt. With this estimate, we can prove the global wellposedness of (2.19) with smooth and small initial data by using the energy method. We emphasize that the algebraic structure of (2.19) is crucial for the proofs to work. The global wellposedness of the original system (1.1) then follows by a suitable change of variables.
2D Langmuir Maps of Kinked UW-RWM Plasma
NASA Astrophysics Data System (ADS)
Hannum, David; Brookhart, Matt; Forest, Cary; Kendrick, Roch; Mengin, Gabriel; Paz-Soldan, Carlos
2009-11-01
The rotating wall machine is a linear screw-pinch built to study the role of different wall boundary conditions on the Resistive Wall Mode (RWM). Its plasma is created by a hexagonal array of seven electrostatic guns. The guns can be biased to discharge up to 1 kA of current each, firing independently or in tandem. The 20 cm diameter, 1.2 m long plasma column is held in place by a 500 G (max) axial guide field. A singletip Langmuir probe inserted from the opposite end of the chamber yields measurements of Te, ne and Vp in r and z. Though it is tied to the guns at the cathode end, the plasma column is free to slip over the anode end. At higher plasma currents, the kinking column oscillates past the probe tip. Ensemble averaging of the I-V curves is required to derive reliable Langmuir measurements for these plasmas. I will present 2D Langmuir profiles in configurations scanning the plasma current Ip, guide field Bz, and number of plasma sources (one gun / seven guns).
An Investigation of 2D Electrostatic Dust Levitation about Bennu
NASA Astrophysics Data System (ADS)
Hartzell, Christine; Zimmerman, Michael
2015-11-01
Electrostatic dust levitation has been hypothesized to occur near the surface of asteroids, due to the interaction of the solar wind plasma and UV radiation with the asteroids’ surfaces and their near-zero surficial gravity. Dust levitation could provide a mechanism to move regolith across the surface of an asteroid. Our preliminary investigations have identified grains sizes and the altitudes at which grains may levitate considering a semi-analytical 1D plasma model. However, our initial semi-analytical plasma model was not well-suited to the complex terminator region, where the surface transitions between positive (dominated by photoemission) and negative (in the plasma wake) potentials. In this analysis, we use a new 2D treecode-based plasma simulation to more accurately model the plasma environment about a simplified circular cross-section of the asteroid Bennu. We investigate the altitudes and grain sizes where electrostatic levitation could occur at Bennu. The improved plasma model will allow more accurate predictions of dust levitation and deposition, particularly in the terminator and wake regions that could not be characterized be earlier plasma models.
Tracking of deformable target in 2D ultrasound images
NASA Astrophysics Data System (ADS)
Royer, Lucas; Marchal, Maud; Le Bras, Anthony; Dardenne, Guillaume; Krupa, Alexandre
2015-03-01
In this paper, we propose a novel approach for automatically tracking deformable target within 2D ultrasound images. Our approach uses only dense information combined with a physically-based model and has therefore the advantage of not using any fiducial marker nor a priori knowledge on the anatomical environment. The physical model is represented by a mass-spring damper system driven by different types of forces where the external forces are obtained by maximizing image similarity metric between a reference target and a deformed target across the time. This deformation is represented by a parametric warping model where the optimal parameters are estimated from the intensity variation. This warping function is well-suited to represent localized deformations in the ultrasound images because it directly links the forces applied on each mass with the motion of all the pixels in its vicinity. The internal forces constrain the deformation to physically plausible motions, and reduce the sensitivity to the speckle noise. The approach was validated on simulated and real data, both for rigid and free-form motions of soft tissues. The results are very promising since the deformable target could be tracked with a good accuracy for both types of motion. Our approach opens novel possibilities for computer-assisted interventions where deformable organs are involved and could be used as a new tool for interactive tracking of soft tissues in ultrasound images.
Steady propagation of Bingham plugs in 2D channels
NASA Astrophysics Data System (ADS)
Zamankhan, Parsa; Takayama, Shuichi; Grotberg, James
2009-11-01
The displacement of the yield-stress liquid plugs in channels and tubes occur in many biological systems and industrial processes. Among them is the propagation of mucus plugs in the respiratory tracts as may occur in asthma, cystic fibrosis, or emphysema. In this work the steady propagation of mucus plugs in a 2D channel is studied numerically, assuming that the mucus is a pure Bingham fluid. The governing equations are solved by a mixed-discontinuous finite element formulation and the free surface is resolved with the method of spines. The constitutive equation for a pure Bingham fluid is modeled by a regularization method. Fluid inertia is neglected, so the controlling parameters in a steady displacement are; the capillary number, Ca, Bingham number ,Bn, and the plug length. According to the numerical results, the yield stress behavior of the plug modifies the plug shape, the pattern of the streamlines and the distribution of stresses in the plug domain and along the walls in a significant way. The distribution along the walls is a major factor in studying cell injuries. This work is supported through the grant NIH HL84370.
cosmoxi2d: Two-point galaxy correlation function calculation
NASA Astrophysics Data System (ADS)
Reid, Beth
2013-07-01
Cosmoxi2d is written in C and computes the theoretical two-point galaxy correlation function as a function of cosmological and galaxy nuisance parameters. It numerically evaluates the model described in detail in Reid and White 2011 (arxiv:1105.4165) and Reid et al. 2012 (arxiv:1203.6641) for the multipole moments (up to ell = 4) for the observed redshift space correlation function of biased tracers as a function of cosmological (though an input linear matter power spectrum, growth rate f, and Alcock-Paczynski geometric factors alphaperp and alphapar) as well as nuisance parameters describing the tracers (bias and small scale additive velocity dispersion, isotropicdisp1d). This model works best for highly biased tracers where the 2nd order bias term is small. On scales larger than 100 Mpc, the code relies on 2nd order Lagrangian Perturbation theory as detailed in Matsubara 2008 (PRD 78, 083519), and uses the analytic version of Reid and White 2011 on smaller scales.
NASA Astrophysics Data System (ADS)
Byron, S.
1985-03-01
The low pressure gas-filled thyratron is scalable in the long dimension. Internally the tube is formed as a tetrode, with an auxiliary grid placed between the cathode and the control grid. A dc or pulsed power source drives the auxiliary grid both to insure uniform cathode emission and to provide a grid-cathode plasma prior to commutation. The high voltage holdoff structure consists of the anode, the control grid and its electrostatic shielding baffles, and a main quartz insulator. A small gas flow supply and exhaust system is used that eliminates the need for a hydrogen reservoir and permits other gases, such as helium, to be used. The thyratron provides a low inductance, high current, long lifetime switch configuration: useful for switch-on applications involving large scale lasers and other similar loads that are distributed in a linear geometry.
Bertrand Duplantier
2006-08-23
In these Notes, a comprehensive description of the universal fractal geometry of conformally-invariant scaling curves or interfaces, in the plane or half-plane, is given. The present approach focuses on deriving critical exponents associated with interacting random paths, by exploiting their underlying quantum gravity structure. The latter relates exponents in the plane to those on a random lattice, i.e., in a fluctuating metric, using the so-called Knizhnik, Polyakov and Zamolodchikov (KPZ) map. This is accomplished within the framework of random matrix theory and conformal field theory, with applications to geometrical critical models, like Brownian paths, self-avoiding walks, percolation, and more generally, the O(N) or Q-state Potts models and, last but not least, Schramm's Stochastic Loewner Evolution (SLE_kappa). These Notes can be considered as complementary to those by Wendelin Werner (2006 Fields Medalist!), ``Some Recent Aspects of Random Conformally Invariant Systems,'' arXiv:math.PR/0511268.
Critique of information geometry
Skilling, John
2014-12-05
As applied to probability, information geometry fails because probability distributions do not form a metric space. Probability theory rests on a compelling foundation of elementary symmetries, which also support information (aka minus entropy, Kullback-Leibler) H(p;q) as the unique measure of divergence from source probability distribution q to destination p. Because the only compatible connective H is from?to asymmetric, H(p;q)?H(q;p), there can be no compatible geometrical distance (which would necessarily be from=to symmetric). Hence there is no distance relationship compatible with the structure of probability theory. Metrics g and densities sqrt(det(g)) interpreted as prior probabilities follow from the definition of distance, and must fail likewise. Various metrics and corresponding priors have been proposed, Fisher's being the most popular, but all must behave unacceptably. This is illustrated with simple counter-examples.
Quantum computational geometry
NASA Astrophysics Data System (ADS)
Lanzagorta, Marco; Uhlmann, Jeffrey K.
2004-08-01
The prospects for practical quantum computing have improved significantly over the past few years, and there is an increasing motivation for developing quantum algorithms to address problems that are presently impractical to solve using classical computing. In previous work we have indentified such problems in the areas of computer graphics applications, and we have derived quantum-based solutions. In this paper we examine quantum-based solutions to problems arising in the area of computational geometry. These types of problems are important in a variety of scientific, industrial and military applications such as large scale multi-object simulation, virtual reality systems, and multi-target tracking. In particular, we present quantum algorithms for multidimensional searches, convex hull construction, and collision detection.
Advanced geometries and regimes
NASA Astrophysics Data System (ADS)
Bulanov, S. S.; Bulanov, S. V.; Turchetti, G.; Limpouch, J.; Klimo, O.; Psikal, J.; Stockem, A.; Fiuza, F.; Silva, L. O.; Antici, P.; Margarone, D.; Korn, G.
2013-08-01
We review and discuss different schemes of laser ion acceleration as well as advanced target geometries in connection with the development of the laser-driven proton source for hadron therapy of oncological diseases, which is a part of the ELIMED project. At the request of the Proceedings Editors and Dr. Stepan Bulanov, University of California, Berkeley, the above article has been updated to include three additional authors: A. Stockem, F. Fiuza, and L. O. Silva. All additional authors have consented to their name being added to the paper. Furthermore, the updated article PDF contains amendments to a number of references as detailed within the pages attached to the end of the updated article PDF file. The updated article was re-published on 8 August 2013.
Correa, Diego H.; Silva, Guillermo A.
2008-07-28
We discuss how geometrical and topological aspects of certain (1/2)-BPS type IIB geometries are captured by their dual operators in N = 4 Super Yang-Mills theory. The type IIB solutions are characterized by arbitrary droplet pictures in a plane and we consider, in particular, axially symmetric droplets. The 1-loop anomalous dimension of the dual gauge theory operators probed with single traces is described by some bosonic lattice Hamiltonians. These Hamiltonians are shown to encode the topology of the droplets. In appropriate BMN limits, the Hamiltonians spectrum reproduces the spectrum of near-BPS string excitations propagating along each of the individual edges of the droplet. We also study semiclassical regimes for the Hamiltonians. For droplets having disconnected constituents, the Hamiltonian admits different complimentary semiclassical descriptions, each one replicating the semiclassical description for closed strings extending in each of the constituents.
NASA Astrophysics Data System (ADS)
Ueberschär, Olaf; Almeida, Maria J.; Matthes, Patrick; Müller, Mathias; Ecke, Ramona; Exner, Horst; Schulz, Stefan E.
2015-09-01
We have designed and fabricated 2D GMR spin valve sensors on the basis of IrMn/CoFe/Cu/CoFe/NiFe nanolayers in monolithic integration for high sensitivity applications. For a maximum signal-to-noise ratio, we realize a focused double full bridge layout featuring an antiparallel exchange bias pinning for neighbouring meanders and an orthogonal pinning for different bridges. This precise alignment is achieved with microscopic precision by laser heating and subsequent in-field cooling. Striving for maximum signal sensitivity and minimum hysteresis, we study in detail the impact of single meander geometry on the total magnetic structure and electronic transport properties. The investigated geometrical parameters include stripe width, stripe length, cross bar material and total meander length. In addition, the influence of the relative alignment between reference magnetization (pinned layer) and shape anisotropy (free layer) is studied. The experimentally obtained data are moreover compared to the predictions of tailored micromagnetic simulations. Using a set of optimum parameters, we demonstrate that our sensor may readily be employed to measure small magnetic fields, such as the ambient (geomagnetic) field, in terms of a 2D vector with high spatial (~200 ?m) and temporal (~1 ms) resolution.
NASA Astrophysics Data System (ADS)
Hatt, Charles R.; Speidel, Michael A.; Raval, Amish N.
2014-03-01
We present a novel 2D/ 3D registration algorithm for fusion between transesophageal echocardiography (TEE) and X-ray fluoroscopy (XRF). The TEE probe is modeled as a subset of 3D gradient and intensity point features, which facilitates efficient 3D-to-2D perspective projection. A novel cost-function, based on a combination of intensity and edge features, evaluates the registration cost value without the need for time-consuming generation of digitally reconstructed radiographs (DRRs). Validation experiments were performed with simulations and phantom data. For simulations, in silica XRF images of a TEE probe were generated in a number of different pose configurations using a previously acquired CT image. Random misregistrations were applied and our method was used to recover the TEE probe pose and compare the result to the ground truth. Phantom experiments were performed by attaching fiducial markers externally to a TEE probe, imaging the probe with an interventional cardiac angiographic x-ray system, and comparing the pose estimated from the external markers to that estimated from the TEE probe using our algorithm. Simulations found a 3D target registration error of 1.08(1.92) mm for biplane (monoplane) geometries, while the phantom experiment found a 2D target registration error of 0.69mm. For phantom experiments, we demonstrated a monoplane tracking frame-rate of 1.38 fps. The proposed feature-based registration method is computationally efficient, resulting in near real-time, accurate image based registration between TEE and XRF.
NASA Technical Reports Server (NTRS)
Thompson, David S.; Soni, Bharat K.
2000-01-01
An integrated software package, ICEG2D, was developed to automate computational fluid dynamics (CFD) simulations for single-element airfoils with ice accretion. ICEG2D is designed to automatically perform three primary functions: (1) generating a grid-ready, surface definition based on the geometrical characteristics of the iced airfoil surface, (2) generating a high-quality grid using the generated surface point distribution, and (3) generating the input and restart files needed to run the general purpose CFD solver NPARC. ICEG2D can be executed in batch mode using a script file or in an interactive mode by entering directives from a command line. This report summarizes activities completed in the first year of a three-year research and development program to address issues related to CFD simulations for aircraft components with ice accretion. Specifically, this document describes the technology employed in the software, the installation procedure, and a description of the operation of the software package. Validation of the geometry and grid generation modules of ICEG2D is also discussed.
Is 2-D turbulence relevant in the atmosphere?
NASA Astrophysics Data System (ADS)
Lovejoy, Shaun; Schertzer, Daniel
2010-05-01
Starting with (Taylor, 1935), the paradigm of isotropic (and scaling!) turbulence was developed initially for laboratory applications, but following (Kolmogorov, 1941), three dimensional isotropic turbulence was progressively applied to the atmosphere. Since the atmosphere is strongly stratified, a single wide scale range model which is both isotropic and scaling is not possible so that theorists had to immediately choose between the two symmetries: isotropy or scale invariance. Following the development of models of two dimensional isotropic turbulence ((Fjortoft, 1953), but especially (Kraichnan, 1967) and (Charney, 1971)), the mainstream choice was to first make the convenient assumption of isotropy and to drop wide range scale invariance. Starting at the end of the 1970's this "isotropy primary" (IP) paradigm has lead to a series of increasingly complex isotropic 2D/isotropic 3D models of atmospheric dynamics which continue to dominate the theoretical landscape. Justifications for IP approaches have focused almost exclusively on the horizontal statistics of the horizontal wind in both numerical models and analyses and from aircraft campaigns, especially the highly cited GASP (Nastrom and Gage, 1983), (Gage and Nastrom, 1986; Nastrom and Gage, 1985) and MOZAIC (Cho and Lindborg, 2001) experiments. Since understanding the anisotropy clearly requires comparisons between horizontal and vertical statistics/structures this focus has been unfortunate. Over the same thirty year period that 2D/3D isotropic models were being elaborated, evidence slowly accumulated in favour of the opposite theoretical choice: to drop the isotropy assumption but to retain wide range scaling. The models in the alternative paradigm are scaling but strongly anisotropic with vertical sections of structures becoming increasingly stratified at larger and larger scales albeit in a power law manner; we collectively refer to these as "SP" for "scaling primary" approaches. Early authors explicitly using SP models to explain their observations include ((Van Zandt, 1982), (Schertzer and Lovejoy, 1985), (Schertzer and Lovejoy, 1987), (Fritts et al., 1988), (Tsuda et al., 1989), (Dewan, 1997; Lazarev et al., 1994), (Gardner et al., 1993), (Hostetler and Gardner, 1994). In addition, many experiments found non-standard vertical scaling exponents thus implicitly supporting the SP position. Today, state-of-the-art lidar vertical sections of passive scalars (Lilley et al., 2004) or satellite vertical radar sections of clouds give direct evidence for the corresponding scaling (power law) stratification of structures. State-of-the-art drop sondes have even been used to show that the IP standard bearer - 3D isotropic Kolmogorov turbulence - apparently doesn't exist in the atmosphere at any scale at least down to 5 m in scale or at any altitude level within the troposphere (Lovejoy et al., 2007). At the same time, massive quantities of high quality satellite data have directly demonstrated the wide range horizontal scaling of the atmospheric forcing (long and short wave radiances; see e.g. (Lovejoy et al., 2009a)) and numerical atmospheric models and reanalyses have been shown to display nearly perfect (scaling) cascade structures over their entire available horizontal ranges (Stolle et al., 2009). This shows also that the source/sink free "inertial ranges" used in IP models are at best academic idealizations. The IP/SP opposition is arguably a main contributor to today's lack of scientific consensus about the scale by scale statistical structure of both the atmosphere and of atmospheric models and reanalyses. In order to resolve the deadlock, either the IP camp must show how the findings of wide range vertical and horizontal scaling can be adequately explained through a hierarchy of isotropic models, or the SP camp must explain the key aircraft and numerical model results cited against them as evidence of two (or more) isotropic regimes. In this talk we review the debate and argue that now exactly such a reinterpretation of th
A new 2D-tiled detector for multislice CT
NASA Astrophysics Data System (ADS)
Luhta, Randy; Chappo, Marc; Harwood, Brian; Mattson, Rod; Salk, Dave; Vrettos, Chris
2006-03-01
The tremendous increase in speed with which the body can now be scanned using multislice CT has improved the diagnostic ability of the modality, especially in time critical applications involving contrast injection. Advances in photodiode and front-end electronics technology now allow a CT detector module to be made that can be tiled in two dimensions. An array of such modules can be used to easily make a CT scanner with hundreds of slices with the promise of scanning whole organs with a single revolution and further improving diagnostic ability. Recently, a back-illuminated photodiode for CT has been developed which has its electrical connections on the underside. With all four sides of the silicon chip free, the photodiodes can be tiled in two dimensions. In addition, improvements in front-end electronics now allow the A/D converters for all photodiode elements to be placed completely behind the photodiode. A prototype detector module has been constructed and tested. Measurements of DQE, MTF, dynamic range and temporal response are presented showing that the module has the same high performance as detectors found in current diagnostic CT scanners. A dynamic range of 250,000:1 at a frame rate of 10,000 fps has been achieved. Alternatively a dynamic range of 1,000,000:1 can be achieved at 2,500 fps. This new compact 2D tiled detector with digital data output can be used as a basic building block for future multislice detection systems enabling larger coverage and the promise of improved diagnostic ability.
New optical 2D modulator jacketed in rotational plastic optics
NASA Astrophysics Data System (ADS)
Heinol, Horst-Guenther; Xu, Zhanping; Schwarte, Rudolf; Loffeld, Otmar
1995-12-01
Optical and therefore nontactile 3D-measurement techniques are of increasing interest in industrial automation, especially in quality control and guidance of automotive vehicles. In connection with these demands, a new type of optical modulator jacketed in rotational plastic optics is introduced in the paper. Furthermore first results obtained by simulation studies will be presented. A simple nevertheless effective way of obtaining 3D information is to illuminate the whole 3D object or scene simultaneously with rf-modulated light. This can be well achieved by using the suggested optical modulator that incorporates the properties of a high aperture and minimum aberration in the 3D-imaging process. The mentioned modulator makes use of the effect of Frustrated Total Reflection (FTR). To exploit this FTR effect in an optical 2D mixer, the gap width between media of higher dense has to be modulated by an rf-voltage applied to a piezo crystal as an rf-controlled tuning medium. Considering the limited modulation bandwidth due to the parasitic capacity of the piezo crystal, the geometrical dimension of the modulator must be made as small as possible. Therefore the spot of the light is collimated at the focal point of the jacketing rotational ellipsoid. The integrated component made of plastic optics and piezo crystal plays a substantial role for the optical modulation and imaging. Some simulation results of this optical device show that the inherent non-linearity of the FTR modulator may be neglected in practical applications, thus yielding a high modulation depth. Furthermore, a 3D-image system adopting this plastic-made optics is also depicted in the paper, which is robust and handy for several industrial applications.
Cascading rainfall uncertainties into 2D inundation impact models
NASA Astrophysics Data System (ADS)
Souvignet, Maxime; de Almeida, Gustavo; Champion, Adrian; Garcia Pintado, Javier; Neal, Jeff; Freer, Jim; Cloke, Hannah; Odoni, Nick; Coxon, Gemma; Bates, Paul; Mason, David
2013-04-01
Existing precipitation products show differences in their spatial and temporal distribution and several studies have presented how these differences influence the ability to predict hydrological responses. However, an atmospheric-hydrologic-hydraulic uncertainty cascade is seldom explored and how, importantly, input uncertainties propagate through this cascade is still poorly understood. Such a project requires a combination of modelling capabilities, runoff generation predictions based on those rainfall forecasts, and hydraulic flood wave propagation based on the runoff predictions. Accounting for uncertainty in each component is important in decision making for issuing flood warnings, monitoring or planning. We suggest a better understanding of uncertainties in inundation impact modelling must consider these differences in rainfall products. This will improve our understanding of the input uncertainties on our predictive capability. In this paper, we propose to address this issue by i) exploring the effects of errors in rainfall on inundation predictive capacity within an uncertainty framework, i.e. testing inundation uncertainty against different comparable meteorological conditions (i.e. using different rainfall products). Our method cascades rainfall uncertainties into a lumped hydrologic model (FUSE) within the GLUE uncertainty framework. The resultant prediction uncertainties in discharge provide uncertain boundary conditions, which are cascaded into a simplified shallow water 2D hydraulic model (LISFLOOD-FP). Rainfall data captured by three different measurement techniques - rain gauges, gridded data and numerical weather predictions (NWP) models are used to assess the combined input data and model parameter uncertainty. The study is performed in the Severn catchment over the period between June and July 2007, where a series of rainfall events causing record floods in the study area). Changes in flood area extent are compared and the uncertainty envelope is analysed for the different cases. These results demonstrate how rainfall input uncertainty affects the resultant set of behavioural models and what rainfall products produce robust predictions within an uncertainty analysis framework. This addresses the question of how storm impact models might be improved with next generation NWP models.