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Sample records for 2d hole system

  1. Spin-Orbit Interaction and Related Transport Phenomena in 2d Electron and Hole Systems

    NASA Astrophysics Data System (ADS)

    Khaetskii, A.

    Spin-orbit interaction is responsible for many physical phenomena which are under intensive study currently. Here we discuss several of them. The first phenomenon is the edge spin accumulation, which appears due to spin-orbit interaction in 2D mesoscopic structures in the presence of a charge current. We consider the case of a strong spin-orbit-related splitting of the electron spectrum, i.e. a spin precession length is small compared to the mean free path l. The structure can be either in a ballistic regime (when the mean free path is the largest scale in the problem) or quasi-ballistic regime (when l is much smaller than the sample size). We show how physics of edge spin accumulation in different situations should be understood from the point of view of unitarity of boundary scattering. Using transparent method of scattering states, we are able to explain some previous puzzling theoretical results. We clarify the important role of the form of the spin-orbit Hamiltonian, the role of the boundary conditions, etc., and reveal the wrong results obtained in the field by other researchers. The relation between the edge spin density and the bulk spin current in different regimes is discussed. The detailed comparison with the existing theoretical works is presented. Besides, we consider several new transport phenomena which appear in the presence of spin-orbit interaction, for example, magnetotransport phenomena in an external classical magnetic field. In particular, new mechanism of negative magneto-resistance appears which is due to destruction of spin fluxes by the magnetic field, and which can be really pronounced in 2D systems with strong scatterers.

  2. Discovery of a Novel Linear-in-k Spin Splitting for Holes in the 2D GaAs/AlAs System

    SciTech Connect

    Luo, J. W.; Chantis, A. N.; van Schilfgaarde, M.; Bester, G.; Zunger, A.

    2010-02-12

    The spin-orbit interaction generally leads to spin splitting (SS) of electron and hole energy states in solids, a splitting that is characterized by a scaling with the wave vector k. Whereas for 3D bulk zinc blende solids the electron (heavy-hole) SS exhibits a cubic (linear) scaling with k, in 2D quantum wells, the electron (heavy-hole) SS is currently believed to have a mostly linear (cubic) scaling. Such expectations are based on using a small 3D envelope function basis set to describe 2D physics. By treating instead the 2D system explicitly as a system in its own right, we discover a large linear scaling of hole states in 2D. This scaling emerges from coupling of hole bands that would be unsuspected by the standard model that judges coupling by energy proximity. This discovery of a linear Dresselhaus k scaling for holes in 2D implies a different understanding of hole physics in low dimensions.

  3. Direct observation of an out-of-plane spin polarization caused by an in-plane magnetic field in a GaAs 2D hole system

    NASA Astrophysics Data System (ADS)

    Yeoh, Lareine; Srinivasan, Ashwin; Klochan, Oleh; Micolich, Adam; Winkler, Roland; Simmons, Michelle; Ritchie, David; Pepper, Michael; Hamilton, Alexander

    2014-03-01

    Recent interest in spin-orbit coupling has led to studies of quantum confined, hole based semiconductor devices, which naturally possess strong spin-orbit interaction due to the intrinsic spin-3/2 nature of holes. In general both crystal anisotropies and quantum confinement will affect the spin properties of holes. In high symmetry crystals such anisotropies can be ignored, however in low symmetry crystals this complex interplay between the crystal and the confining potential gives rise to intriguing spin behavior, which has no counterpart in spin-1/2 electron-based systems. Here I will present the first direct observations of an unusual effect where a magnetic field applied in the plane of the 2D hole system generates a spin polarization perpendicular to the 2D plane. This out-of-plane spin polarisation is detected in transport measurements of a symmetrically doped, GaAs 2D hole quantum well in tilted magnetic fields. We are able to extract the sign of this off-diagonal component of the Landé g-factor and show that it is consistent with theory.

  4. Frictional drag between two dilute 2D hole layers

    NASA Astrophysics Data System (ADS)

    Pillarisetty, R.; Noh, H.; Tsui, D. C.; de Poortere, E. P.; Tutuc, E.; Shayegan, M.

    2002-03-01

    We present results of drag measurements on 2D hole systems in the low density limit (rs ranging from 19 to 39), close to their apparent B=0 metal to insulator transitions at p ~ 8.5×10^9 cm-2. The drag resistivity(ρ_D) of our sample, with a 300 Å center to center quantum well separation, is 1.5 kΩ/ Box for 1.5×10^10 cm-2 at 1 K. This is sufficiently large to allow measurements at dilution fridge temperatures to study whether the 2D hole systems show non-Fermi liquid behavior. We find that for Talt0.5T_F, the data exhibit a slightly stronger than T^2 dependence. As the temperature is further increased we find a crossover to a linear dependence, and ρ_D/T^2 vs T exhibits a peak similar to that observed in previous experiments involving phonon mediated electron-electron scattering and plasmon enhancement. Unlike these previous reports, which exhibited a local maxima in ρD around matched densities, our samples show a clearly monotonic dependence upon either layer density. These results will be discussed in light of interaction effects expected in such a large rs regime.

  5. Strongly Metallic Electron and Hole 2D Transport in an Ambipolar Si-Vacuum Field Effect Transistor

    NASA Astrophysics Data System (ADS)

    Hu, Binhui; Yazdanpanah, M. M.; Kane, B. E.; Hwang, E. H.; Das Sarma, S.

    2015-07-01

    We report experiment and theory on an ambipolar gate-controlled Si(111)-vacuum field effect transistor where we study electron and hole (low-temperature 2D) transport in the same device simply by changing the external gate voltage to tune the system from being a 2D electron system at positive gate voltage to a 2D hole system at negative gate voltage. The electron (hole) conductivity manifests strong (moderate) metallic temperature dependence with the conductivity decreasing by a factor of 8 (2) between 0.3 K and 4.2 K with the peak electron mobility (˜18 m2/V s ) being roughly 20 times larger than the peak hole mobility (in the same sample). Our theory explains the data well using random phase approximation screening of background Coulomb disorder, establishing that the observed metallicity is a direct consequence of the strong temperature dependence of the effective screened disorder.

  6. Surprises in the evaporation of 2D black holes.

    PubMed

    Ashtekar, Abhay; Pretorius, Frans; Ramazanoğlu, Fethi M

    2011-04-22

    Quantum evaporation of Callan-Giddings-Harvey-Strominger black holes is analyzed in the mean-field approximation, incorporating backreaction. Detailed analytical and numerical calculations show that, while some of the assumptions underlying the standard evaporation paradigm are borne out, several are not. Furthermore, if the black hole is initially macroscopic, the evaporation process exhibits remarkable universal properties (which are distinct from the features observed in the simplified, exactly soluble models). Finally, our results provide support for the full quantum gravity scenario recently developed by Ashtekar, Taveras, and Varadarajan. PMID:21599354

  7. New 2D dilaton gravity for nonsingular black holes

    NASA Astrophysics Data System (ADS)

    Kunstatter, Gabor; Maeda, Hideki; Taves, Tim

    2016-05-01

    We construct a two-dimensional action that is an extension of spherically symmetric Einstein-Lanczos-Lovelock (ELL) gravity. The action contains arbitrary functions of the areal radius and the norm squared of its gradient, but the field equations are second order and obey Birkhoff’s theorem. In complete analogy with spherically symmetric ELL gravity, the field equations admit the generalized Misner-Sharp mass as the first integral that determines the form of the vacuum solution. The arbitrary functions in the action allow for vacuum solutions that describe a larger class of interesting nonsingular black hole spacetimes than previously available.

  8. The 2D lingual appliance system.

    PubMed

    Cacciafesta, Vittorio

    2013-09-01

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

  9. Phosphorene: an unexplored 2D semiconductor with a high hole mobility.

    PubMed

    Liu, Han; Neal, Adam T; Zhu, Zhen; Luo, Zhe; Xu, Xianfan; Tománek, David; Ye, Peide D

    2014-04-22

    We introduce the 2D counterpart of layered black phosphorus, which we call phosphorene, as an unexplored p-type semiconducting material. Same as graphene and MoS2, single-layer phosphorene is flexible and can be mechanically exfoliated. We find phosphorene to be stable and, unlike graphene, to have an inherent, direct, and appreciable band gap. Our ab initio calculations indicate that the band gap is direct, depends on the number of layers and the in-layer strain, and is significantly larger than the bulk value of 0.31-0.36 eV. The observed photoluminescence peak of single-layer phosphorene in the visible optical range confirms that the band gap is larger than that of the bulk system. Our transport studies indicate a hole mobility that reflects the structural anisotropy of phosphorene and complements n-type MoS2. At room temperature, our few-layer phosphorene field-effect transistors with 1.0 μm channel length display a high on-current of 194 mA/mm, a high hole field-effect mobility of 286 cm(2)/V·s, and an on/off ratio of up to 10(4). We demonstrate the possibility of phosphorene integration by constructing a 2D CMOS inverter consisting of phosphorene PMOS and MoS2 NMOS transistors. PMID:24655084

  10. 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.

  11. Periodically sheared 2D Yukawa systems

    SciTech Connect

    Kovács, Anikó Zsuzsa; Hartmann, Peter; Donkó, Zoltán

    2015-10-15

    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.

  12. Impact of Interface Roughness on the Metallic Transport of Strongly Correlated 2D Holes in GaAs Quantum Wells

    NASA Astrophysics Data System (ADS)

    Goble, Nicholas; Watson, John; Manfra, Michael; Gao, Xuan

    2014-03-01

    Understanding the non-monotonic behavior in the temperature dependent resistance, R(T) , of strongly correlated two-dimensional (2D) carriers in clean semiconductors has been a central issue in the studies of 2D metallic states and metal-insulator transitions. We have studied the transport of high mobility 2D holes in 20nm wide GaAs quantum wells with varying interface roughness by changing the Al fraction x in the AlxGa1-xAs barrier. Prior to this work, no comprehensive study of the non-monotonic resistance peak against controlled barrier characteristics has been conducted. We show that the shape of the electronic contribution to R(T) is qualitatively unchanged throughout all of our measurements, regardless of the percentage of Al in the barrier. It is observed that increasing x or short range interface roughness suppresses both the strength and characteristic temperature scale of the 2D metallicity, pointing to the distinct role of short range versus long range disorder in the 2D metallic transport in this 2D hole system with interaction parameter rs ~ 20. N.G. acknowledges the US DOE GAANN fellowship (P200A090276 & P200A070434). M.J.M. is supported by the Miller Family Foundation and the US DOE, Office of Basic Energy Sciences, DMS (DE-SC0006671). X.P.A.G thanks the NSF for funding support (DMR-0906415).

  13. Quantum (in)stability of 2D charged dilaton black holes and 3D rotating black holes

    NASA Astrophysics Data System (ADS)

    Nojiri, Shin'ichi; Odintsov, Sergei D.

    1999-02-01

    The quantum properties of charged black holes (BHs) in two-dimensional (2D) dilaton-Maxwell gravity (spontaneously compactified from heterotic string) with N dilaton coupled scalars are studied. We first investigate 2D BHs found by McGuigan, Nappi, and Yost. Kaluza-Klein reduction of 3D gravity with minimal scalars leads also to 2D dilaton-Maxwell gravity with dilaton coupled scalars and the rotating BH solution found by Bañados, Teitelboim, and Zanelli, which can be also described by 2D charged dilatonic BHs. Evaluating the one-loop effective action for dilaton coupled scalars in large N (and the s-wave approximation for the Bañados-Teitelboim-Zanelli case), we show that quantum-corrected BHs may evaporate or else antievaporate similarly to 4D Nariai BHs as is observed by Bousso and Hawking. Higher modes may cause the disintegration of BHs in accordance with recent observation by Bousso.

  14. A SPITZER c2d LEGACY SURVEY TO IDENTIFY AND CHARACTERIZE DISKS WITH INNER DUST HOLES

    SciTech Connect

    Merin, Bruno; Brown, Joanna M.; Herczeg, Gregory J.; Van Dishoeck, Ewine F.; Oliveira, Isa; Lahuis, Fred; Bottinelli, Sandrine; Augereau, Jean-Charles; Olofsson, Johan; Evans, Neal J.; Harvey, Paul M.; Cieza, Lucas; Spezzi, Loredana; Prusti, Timo; Alcala, Juan M.; Blake, Geoffrey A.; Bayo, Amelia; Geers, Vincent G.; Walter, Frederick M.; Chiu, Kuenley

    2010-08-01

    Understanding how disks dissipate is essential to studies of planet formation. However, identifying exactly how dust and gas dissipate is complicated due to the difficulty of finding objects that are clearly in the transition phase of losing their surrounding material. We use Spitzer Infrared Spectrograph (IRS) spectra to examine 35 photometrically selected candidate cold disks (disks with large inner dust holes). The infrared spectra are supplemented with optical spectra to determine stellar and accretion properties and 1.3 mm photometry to measure disk masses. Based on detailed spectral energy distribution modeling, we identify 15 new cold disks. The remaining 20 objects have IRS spectra that are consistent with disks without holes, disks that are observed close to edge-on, or stars with background emission. Based on these results, we determine reliable criteria to identify disks with inner holes from Spitzer photometry, and examine criteria already in the literature. Applying these criteria to the c2d surveyed star-forming regions gives a frequency of such objects of at least 4% and most likely of order 12% of the young stellar object population identified by Spitzer. We also examine the properties of these new cold disks in combination with cold disks from the literature. Hole sizes in this sample are generally smaller than in previously discovered disks and reflect a distribution in better agreement with exoplanet orbit radii. We find correlations between hole size and both disk and stellar masses. Silicate features, including crystalline features, are present in the overwhelming majority of the sample, although the 10 {mu}m feature strength above the continuum declines for holes with radii larger than {approx}7 AU. In contrast, polycyclic aromatic hydrocarbons are only detected in 2 out of 15 sources. Only a quarter of the cold disk sample shows no signs of accretion, making it unlikely that photoevaporation is the dominant hole-forming process in most cases.

  15. D-brane Falling into 2d Black-hole and Closed String Radiation

    NASA Astrophysics Data System (ADS)

    Sugawara, Yuji

    2005-12-01

    We study the dynamics of D0-brane falling into the Lorentzian 2-dimensional black hole (2D BH), typically arising in the near-horizon limit of non-extremal NS5-brane background, by the methods of boundary state. The `falling D0-brane' is expected to be obtained by the Wick rotation from the known D1-brane solution on the Euclidean 2D BH. Despite its easiness in the classical solution, the Wick rotation in the boundary conformal theory is rather non-trivial due to ambiguities of boundary conditions. We propose the exact boundary state describing it, clarifying the role of boundary condition. We also evaluate the closed string radiation from the infalling brane. An expected thermal-like behavior at the Hawking temperature is observed in the outgoing radiation. On the other hand, it is remarkably found that the incoming radiation absorbed by the black hole effectively shows the Hagedorn-like behavior with precise α'-correction. This fact implies that the radiation products are dominated by very massive, highly non-relativistic closed string states like the tachyon matter. The radiation rate curiously depends on the level k of SL(2)/U(1) supercoset, suggesting the `black hole/string phase transition' at k = 1 (k = 3 for the bosonic coset) discussed recently.

  16. Geometric properties of a 2 D spacetime arising in 4 D black hole physics

    NASA Astrophysics Data System (ADS)

    Casals, Marc; Nolan, Brien C.

    2015-11-01

    The Schwarzschild exterior space-time is conformally related to a direct product space-time, M2×S2 , where M2 is a 2 D space-time. This direct product structure arises naturally when considering the wave equation on the Schwarzschild background. Motivated by this, we establish some geometrical results relating to M2 that are useful for black hole physics. We prove that M2 has the rare property of being a causal domain. Consequently, Synge's world function and the Hadamard form for the Green function on this space-time are well defined globally. We calculate the world function and the van Vleck determinant on M2 numerically and point out how these results will be used to establish global properties of Green functions on the Schwarzschild black hole space-time.

  17. Observation of Rashba zero-field spin splitting in a strained germanium 2D hole gas

    SciTech Connect

    Morrison, C. Rhead, S. D.; Foronda, J.; Leadley, D. R.; Myronov, M.; Wiśniewski, P.

    2014-11-03

    We report the observation, through Shubnikov-de Haas oscillations in the magnetoresistance, of spin splitting caused by the Rashba spin-orbit interaction in a strained Ge quantum well epitaxially grown on a standard Si(001) substrate. The Shubnikov-de Haas oscillations display a beating pattern due to the spin split Landau levels. The spin-orbit parameter and Rashba spin-splitting energy are found to be 1.0 × 10{sup −28 } eVm{sup 3} and 1.4 meV, respectively. This energy is comparable to 2D electron gases in III-V semiconductors, but substantially larger than in Si, and illustrates the suitability of Ge for modulated hole spin transport devices.

  18. H-FGK formalism for black-hole solutions of N=2, d=4 and d=5 supergravity

    NASA Astrophysics Data System (ADS)

    Meessen, Patrick; Ortín, Tomás; Perz, Jan; Shahbazi, C. S.

    2012-03-01

    We rewrite the Ferrara-Gibbons-Kallosh (FGK) black-hole effective action of N=2, d=4,5 supergravities coupled to vector multiplets, replacing the metric warp factor and the physical scalars with real variables that transform in the same way as the charges under duality transformations, which simplifies the equations of motion. For a given model, the form of the solution in these variables is the same for all spherically symmetric black holes, regardless of supersymmetry or extremality.

  19. Optical imaging systems analyzed with a 2D template.

    PubMed

    Haim, Harel; Konforti, Naim; Marom, Emanuel

    2012-05-10

    Present determination of optical imaging systems specifications are based on performance values and modulation transfer function results carried with a 1D resolution template (such as the USAF resolution target or spoke templates). Such a template allows determining image quality, resolution limit, and contrast. Nevertheless, the conventional 1D template does not provide satisfactory results, since most optical imaging systems handle 2D objects for which imaging system response may be different by virtue of some not readily observable spatial frequencies. In this paper we derive and analyze contrast transfer function results obtained with 1D as well as 2D templates. PMID:22614498

  20. Microscale 2D separation systems for proteomic analysis

    PubMed Central

    Xu, Xin; Liu, Ke; Fan, Z. Hugh

    2012-01-01

    Microscale 2D separation systems have been implemented in capillaries and microfabricated channels. They offer advantages of faster analysis, higher separation efficiency and less sample consumption than the conventional methods, such as liquid chromatography (LC) in a column and slab gel electrophoresis. In this article, we review their recent advancement, focusing on three types of platforms, including 2D capillary electrophoresis (CE), CE coupling with capillary LC, and microfluidic devices. A variety of CE and LC modes have been employed to construct 2D separation systems via sophistically designed interfaces. Coupling of different separation modes has also been realized in a number of microfluidic devices. These separation systems have been applied for the proteomic analysis of various biological samples, ranging from a single cell to tumor tissues. PMID:22462786

  1. On Regularity Criteria for the 2D Generalized MHD System

    NASA Astrophysics Data System (ADS)

    Jiang, Zaihong; Wang, Yanan; Zhou, Yong

    2016-06-01

    This paper deals with the problem of regularity criteria for the 2D generalized MHD system with fractional dissipative terms {-Λ^{2α}u} for the velocity field and {-Λ^{2β}b} for the magnetic field respectively. Various regularity criteria are established to guarantee smoothness of solutions. It turns out that our regularity criteria imply previous global existence results naturally.

  2. BPS black holes in a non-homogeneous deformation of the stu model of N = 2, D = 4 gauged supergravity

    NASA Astrophysics Data System (ADS)

    Klemm, Dietmar; Marrani, Alessio; Petri, Nicolò; Santoli, Camilla

    2015-09-01

    We consider a deformation of the well-known stu model of N = 2, D = 4 supergravity, characterized by a non-homogeneous special Kähler manifold, and by the smallest electric-magnetic duality Lie algebra consistent with its upliftability to five dimensions. We explicitly solve the BPS attractor equations and construct static supersymmetric black holes with radial symmetry, in the context of U(1) dyonic Fayet-Iliopoulos gauging, focussing on axion-free solutions. Due to non-homogeneity of the scalar manifold, the model evades the analysis recently given in the literature. The relevant physical properties of the resulting black hole solution are discussed.

  3. Resonances of piezoelectric plate with embedded 2D electron system

    NASA Astrophysics Data System (ADS)

    Suslov, A. V.

    2009-02-01

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

  4. 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.

  5. Mid-infrared extraordinary transmission through Ga-doped ZnO films with 2D hole arrays

    NASA Astrophysics Data System (ADS)

    Cleary, Justin W.; Nader Esfahani, Nima; Vangala, Shiva; Guo, Junpeng; Hendrickson, Joshua R.; Leedy, Kevin D.; Look, David C.

    2014-03-01

    Extraordinary optical transmission (EOT), through highly conductive ZnO films with sub-wavelength hole arrays is investigated in the long-wavelength infrared regime. EOT is facilitated by the excitation of surface plasmon polaritons (SPPs) on Ga-Doped ZnO films and can be tuned utilizing the physical parameters such as film thickness, period, hole size, and hole shape, as well as doping of the film. Analytical and finite-difference time-domain calculations are completed for 1 micron thick films with square, circular, and triangular hole arrays demonstrating SPP coupling and EOT. The fundamental plasmonic modes are observed in each of these hole shapes at wavelengths that correspond to strong EOT peaks. Doping tunability for these structures is also observed. Ga-doped ZnO films are grown via pulsed laser deposition (PLD) on silicon with plasma frequencies in the near-infrared. The sub-wavelength 2D hole arrays are fabricated in the Ga-doped ZnO films via standard lithography and etching processes. This highly conductive ZnO EOT structure may prove useful in novel integrated components such as tunable biosensors or surface plasmon coupling mechanisms.

  6. Universal Fabrication of 2D Electron Systems in Functional Oxides.

    PubMed

    Rödel, Tobias Chris; Fortuna, Franck; Sengupta, Shamashis; Frantzeskakis, Emmanouil; Fèvre, Patrick Le; Bertran, François; Mercey, Bernard; Matzen, Sylvia; Agnus, Guillaume; Maroutian, Thomas; Lecoeur, Philippe; Santander-Syro, Andrés Felipe

    2016-03-01

    2D electron systems (2DESs) in functional oxides are promising for applications, but their fabrication and use, essentially limited to SrTiO3 -based heterostructures, are hampered by the need for growing complex oxide overlayers thicker than 2 nm using evolved techniques. It is demonstrated that thermal deposition of a monolayer of an elementary reducing agent suffices to create 2DESs in numerous oxides. PMID:26753522

  7. Conformal Laplace superintegrable systems in 2D: polynomial invariant subspaces

    NASA Astrophysics Data System (ADS)

    Escobar-Ruiz, M. A.; Miller, Willard, Jr.

    2016-07-01

    2nd-order conformal superintegrable systems in n dimensions are Laplace equations on a manifold with an added scalar potential and 2n-1 independent 2nd order conformal symmetry operators. They encode all the information about Helmholtz (eigenvalue) superintegrable systems in an efficient manner: there is a 1-1 correspondence between Laplace superintegrable systems and Stäckel equivalence classes of Helmholtz superintegrable systems. In this paper we focus on superintegrable systems in two-dimensions, n = 2, where there are 44 Helmholtz systems, corresponding to 12 Laplace systems. For each Laplace equation we determine the possible two-variate polynomial subspaces that are invariant under the action of the Laplace operator, thus leading to families of polynomial eigenfunctions. We also study the behavior of the polynomial invariant subspaces under a Stäckel transform. The principal new results are the details of the polynomial variables and the conditions on parameters of the potential corresponding to polynomial solutions. The hidden gl 3-algebraic structure is exhibited for the exact and quasi-exact systems. For physically meaningful solutions, the orthogonality properties and normalizability of the polynomials are presented as well. Finally, for all Helmholtz superintegrable solvable systems we give a unified construction of one-dimensional (1D) and two-dimensional (2D) quasi-exactly solvable potentials possessing polynomial solutions, and a construction of new 2D PT-symmetric potentials is established.

  8. Quasinormal modes for single horizon black holes in generic 2D dilaton gravity

    NASA Astrophysics Data System (ADS)

    Kettner, Joanne; Kunstatter, Gabor; Medved, A. J. M.

    2004-12-01

    There has been some recent speculation that a connection may exist between the quasinormal-mode spectra of highly damped black holes and the fundamental theory of quantum gravity. This notion follows from a conjecture by Hod that the real part of the highly damped mode frequencies can be used to calibrate the semi-classical level spacing in the black-hole quantum area spectrum. However, even if the level spacing can be fixed in this manner, it still remains unclear whether this implies a physically significant 'duality' or merely a numerical coincidence. This tapestry of ideas serves as the motivation for the current paper. We utilize the 'monodromy approach' to calculate the quasinormal-mode spectra for a generic class of black holes in two-dimensional dilatonic gravity. Our results agree with the prior literature whenever a direct comparison is possible and provide the analysis of a much more diverse class of black-hole models than previously considered.

  9. Thermal conductivity measurements in a 2D Yukawa system

    NASA Astrophysics Data System (ADS)

    Nosenko, V.; Ivlev, A.; Zhdanov, S.; Morfill, G.; Goree, J.; Piel, A.

    2007-03-01

    Thermal conductivity was measured for a 2D Yukawa system. First, we formed a monolayer suspension of microspheres in a plasma, i.e., a dusty plasma, which is like a colloidal suspension, but with an extremely low volume fraction and a partially-ionized rarefied gas instead of solvent. In the absence of manipulation, the suspension forms a 2D triangular lattice. To melt this lattice and form a liquid, we used a laser-heating method. Two focused laser beams were moved rapidly around in the monolayer. The kinetic temperature of the particles increased with the laser power applied, and above a threshold a melting transition occurred. We used digital video microscopy for direct imaging and particle tracking. The spatial profiles of the particle kinetic temperature were calculated. Using the heat transport equation with an additional term to account for the energy dissipation due to the gas drag, we analyzed the temperature distribution to derive the thermal conductivity.

  10. 2-D linear motion system. Innovative technology summary report

    SciTech Connect

    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

  11. 2D induced gravity from the canonically gauged WZNW system

    NASA Astrophysics Data System (ADS)

    Blagojević, M.; Popović, D. S.; Sazdović, B.

    1999-02-01

    Starting from the Kac-Moody structure of the WZNW model for SL(2,R) and using the general canonical formalism, we formulate a gauge theory invariant under local SL(2,R)×SL(2,R) and diffeomorphisms. This theory represents a gauge extension of the WZNW system, defined by a difference of two simple WZNW actions. By performing a partial gauge fixing and integrating out some dynamical variables, we prove that the resulting effective theory coincides with the induced gravity in 2D. The geometric properties of the induced gravity are obtained out of the gauge properties of the WZNW system with the help of the Dirac brackets formalism.

  12. 2-D scalable optical controlled phased-array antenna system

    NASA Astrophysics Data System (ADS)

    Chen, Maggie Yihong; Howley, Brie; Wang, Xiaolong; Basile, Panoutsopoulos; Chen, Ray T.

    2006-02-01

    A novel optoelectronically-controlled wideband 2-D phased-array antenna system is demonstrated. The inclusion of WDM devices makes a highly scalable system structure. Only (M+N) delay lines are required to control a M×N array. The optical true-time delay lines are combination of polymer waveguides and optical switches, using a single polymeric platform and are monolithically integrated on a single substrate. The 16 time delays generated by the device are measured to range from 0 to 175 ps in 11.6 ps. Far-field patterns at different steering angles in X-band are measured.

  13. Symmetries of the 2D magnetic particle imaging system matrix.

    PubMed

    Weber, A; Knopp, T

    2015-05-21

    In magnetic particle imaging (MPI), the relation between the particle distribution and the measurement signal can be described by a linear system of equations. For 1D imaging, it can be shown that the system matrix can be expressed as a product of a convolution matrix and a Chebyshev transformation matrix. For multidimensional imaging, the structure of the MPI system matrix is not yet fully explored as the sampling trajectory complicates the physical model. It has been experimentally found that the MPI system matrix rows have symmetries and look similar to the tensor products of Chebyshev polynomials. In this work we will mathematically prove that the 2D MPI system matrix has symmetries that can be used for matrix compression. PMID:25919400

  14. Applications of Ultrafast Terahertz Pulses for Intra-ExcitonicSpectroscopy of Quasi-2D Electron-Hole Gases

    SciTech Connect

    Kaindl, Robert A.; Carnahan, Marc A.; Hagele, Daniel; Chemla, D.S.

    2006-09-02

    Excitons are of fundamental interest and of importance foropto-electronic applications of bulk and nano-structured semiconductors.This paper discusses the utilization of ultrafast terahertz (THz) pulsesfor the study of characteristic low-energy excitations of photoexcitedquasi 2D electron-hole (e-h) gases. Optical-pump THz-probe spectroscopyat 250-kHz repetition rate is employed to detect characteristic THzsignatures of excitons and unbound e-h pairs in GaAs quantum wells.Exciton and free-carrier densities are extracted from the data using atwo-component model. We report the detailed THz response and pairdensities for different photoexcitation energies resonant to heavy-holeexcitons, light-hole excitons, or the continuum of unbound pairs. Suchexperiments can provide quantitative insights into wavelength, time, andtemperature dependence of the low-energy response and composition ofoptically excited e-h gases in low-dimensionalsemiconductors.

  15. Dynamics and Central Black Hole of NGC 3377 Based on Sauron and Oasis 2D Spectroscopic Observations

    NASA Astrophysics Data System (ADS)

    Copin, Y.; Cretton, N.; Emsellem, E.; Bacon, R.; Davies, R.; de Zeeuw, T.

    2002-01-01

    We have constrained the central black hole mass and dynamical structure of the E6 galaxy NGC 3377, using axisymmetric dynamical models based on Schwarzschild's orbit method. These models fit simultaneously two sets of 2D-kinematic constraints: i) 475 SAURON spectra, covering the inner 41" x 33" at a spatial resolution of 0.95" and ii) 153 OASIS spectra, covering the inner 4" x 2" at 0.25" resolution. The large radii constraints of SAURON help to fix the dynamical structure of NGC 3377's main body, whereas the higher resolution data from OASIS pin down the black hole mass. I will also describe what kind of improvement in the models is needed to satisfy the increased number of data (compared to the "classical" long-slit spectroscopy).

  16. Measurement of topological invariants in a 2D photonic system

    NASA Astrophysics Data System (ADS)

    Mittal, Sunil; Ganeshan, Sriram; Fan, Jingyun; Vaezi, Abolhassan; Hafezi, Mohammad

    2016-03-01

    A hallmark feature of topological physics is the presence of one-way propagating chiral modes at the system boundary. The chirality of edge modes is a consequence of the topological character of the bulk. For example, in a non-interacting quantum Hall model, edge modes manifest as mid-gap states between two topologically distinct bulk bands. The bulk-boundary correspondence dictates that the number of chiral edge modes, a topological invariant called the winding number, is completely determined by the bulk topological invariant, the Chern number. Here, for the first time, we measure the winding number in a 2D photonic system. By inserting a unit flux quantum at the edge, we show that the edge spectrum resonances shift by the winding number. This experiment provides a new approach for unambiguous measurement of topological invariants, independent of the microscopic details, and could possibly be extended to probe strongly correlated topological orders.

  17. Force-chain identification in quasi-2D granular systems

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  18. Information is not lost in the evaporation of 2D black holes.

    PubMed

    Ashtekar, Abhay; Taveras, Victor; Varadarajan, Madhavan

    2008-05-30

    We analyze Hawking evaporation of the Callan-Giddings-Harvey-Strominger black holes from a quantum geometry perspective and show that information is not lost, primarily because the quantum space-time is sufficiently larger than the classical. Using suitable approximations to extract physics from quantum space-times we establish that (i) the future null infinity of the quantum space-time is sufficiently long for the past vacuum to evolve to a pure state in the future, (ii) this state has a finite norm in the future Fock space, and (iii) all the information comes out at future infinity; there are no remnants. PMID:18518597

  19. A scanning-mode 2D shear wave imaging (s2D-SWI) system for ultrasound elastography.

    PubMed

    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

  20. Fast modular data acquisition system for GEM-2D detector

    NASA Astrophysics Data System (ADS)

    Kasprowicz, G.; Byszuk, Adrian; Wojeński, A.; Zienkiewicz, P.; Czarski, T.; Chernyshova, M.; Poźniak, K.; Rzadkiewicz, J.; Zabolotny, W.; Juszczyk, B.

    2014-11-01

    A novel approach to two dimensional Gas Electron Multiplier (GEM) detector readout is presented. Unlike commonly used methods, based on discriminators and analogue FIFOs, the method developed uses simulta- neously sampling high speed ADCs with fast hybrid integrator and advanced FPGA-based processing logic to estimate the energy of every single photon. Such a method is applied to every GEM strip / pixel signal. It is especially useful in case of crystal-based spectrometers for soft X-rays, 2D imaging for plasma tomography and all these applications where energy resolution of every single photon is required. For the purpose of the detector readout, a novel, highly modular and extendable conception of the measurement platform was developed. It is evolution of already deployed measurement system for JET Spectrometer.

  1. 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.

  2. Evidence for a New Intermediate Phase in a Strongly Correlated 2D System near Wigner Crystallization

    NASA Astrophysics Data System (ADS)

    Gao, Xuan; Qiu, Richard; Goble, Nicholas; Serafin, Alex; Yin, Liang; Xia, Jian-Sheng; Sullivan, Neil; Pfeiffer, Loren; West, Ken

    How the two dimensional (2D) quantum Wigner crystal (WC) transforms into the metallic liquid phase remains an outstanding problem in physics. In theories considering the 2D WC to liquid transition in the clean limit, it was suggested that a number of intermediate phases might exist. We have studied the transformation between the metallic fluid phase and the low magnetic field reentrant insulating phase (RIP) which was interpreted as due to the WC [Qiu et al., PRL 108, 106404 (2012)], in a strongly correlated 2D hole system in GaAs quantum well with large interaction parameter rs (~20-30) and high mobility. Instead of a sharp transition, we found that increasing density (or lowering rs) drives the RIP into a state where the incipient RIP coexists with Fermi liquid. This apparent mixture phase intermediate between Fermi liquid and WC also exhibits a non-trivial temperature dependent resistivity behavior which can be qualitatively understood by the reversed melting of WC in the mixture, in analogy to the Pomeranchuk effect in the solid-liquid mixture of Helium-3. X.G. thanks NSF (DMR-0906415) for supporting work at CWRU. Experiments at the NHMFL High B/T Facility were supported by NSF Grant 0654118 and the State of Florida. L.P. thanks the Gordon and Betty Moore Foundation and NSF MRSEC (DMR-0819860) for support.

  3. Black holes and black strings of N = 2, d = 5 supergravity in the H-FGK formalism

    NASA Astrophysics Data System (ADS)

    Meessen, Patrick; Ortín, Tomás; Perz, Jan; Shahbazi, C. S.

    2012-09-01

    We study general classes and properties of extremal and non-extremal static black-hole solutions of N = 2, d = 5 supergravity coupled to vector multiplets using the recently proposed H-FGK formalism, which we also extend to static black strings. We explain how to determine the integration constants and physical parameters of the blackhole and black-string solutions. We derive some model-independent statements, including the transformation of non-extremal flow equations to the form of those for the extremal flow. We apply our methods to the construction of example solutions (among others a new extremal string solution of heterotic string theory on K 3 × S 1). In the cases where we have calculated it explicitly, the product of areas of the inner and outer horizon of a non-extremal solution coincides with the square of the moduli-independent area of the horizon of the extremal solution with the same charges.

  4. Long-wavelength infrared surface plasmons on Ga-doped ZnO films excited via 2D hole arrays for extraordinary optical transmission

    NASA Astrophysics Data System (ADS)

    Cleary, Justin W.; Esfahani, Nima Nader; Vangala, Shivashankar; Guo, Junpeng; Hendrickson, Joshua R.; Leedy, Kevin D.; Thomson, Darren; Look, David C.

    2013-09-01

    Extraordinary optical transmission (EOT) through highly conductive ZnO films with sub-wavelength hole arrays is investigated in the long-wavelength infrared regime. EOT is facilitated by the excitation of surface plasmon polaritons (SPPs) and can be tuned utilizing the physical structure size such as period. Pulse laser deposited Ga-doped ZnO has been shown to have fluctuations in optical and electrical parameters based on fabrication techniques, providing a complimentary tuning means. The sub-wavelength 2D hole arrays are fabricated in the Ga-doped ZnO films via standard lithography and etching processes. Optical reflection measurements completed with a microscope coupled FTIR system contain absorption resonances that are in agreement with analytical theories for excitation of SPPs on 2D structures. EOT through Ga-doped ZnO is numerically demonstrated at wavelengths where SPPs are excited. This highly conductive ZnO EOT structure may prove useful in novel integrated components such as tunable biosensors or surface plasmon coupling mechanisms.

  5. Effect of open hole on tensile failure properties of 2D triaxial braided textile composites and tape equivalents

    NASA Technical Reports Server (NTRS)

    Norman, Timothy L.; Anglin, Colin; Gaskin, David; Patrick, Mike

    1995-01-01

    The unnotched and notched (open hole) tensile strength and failure mechanisms of two-dimensional (2D) triaxial braided composites were examined. The effect of notch size and notch position were investigated. Damage initiation and propagation in notched and unnotched coupons were also examined. Theory developed to predict the normal stress distribution near an open hole and failure for tape laminated composites was evaluated for its applicability to triaxial braided textile composite materials. Four fiber architectures were considered with different combinations of braid angle, longitudinal and braider yam size, and percentage of longitudinal yarns. Tape laminates equivalent to textile composites were also constructed for comparison. Unnotched tape equivalents were stronger than braided textiles but exhibited greater notch sensitivity. Notched textiles and tape equivalents have roughly the same strength at large notch sizes. Two common damage mechanisms were found: braider yams cracking and near notch longitudinal yarn splitting. Cracking was found to initiate in braider yarns in unnotched and notched coupons, and propagate in the direction of the braider yarns until failure. Longitudinal yarn splitting occurred in three of four architectures that were longitudinally fiber dominated. Damage initiation stress decreased with increasing braid angle. No significant differences in prediction of near notch stress between measured and predicted stress were weak for textiles with large braid angle. Notch strength could not be predicted using existing anisotropic theory for braided textiles due to their insensitivity to notch.

  6. The effect of electron-hole scattering on transport properties of a 2D semimetal in the HgTe quantum well

    SciTech Connect

    Entin, M. V.; Magarill, L. I.; Olshanetsky, E. B. Kvon, Z. D.; Mikhailov, N. N.; Dvoretsky, S. A.

    2013-11-15

    The influence of e-h scattering on the conductivity and magnetotransport of 2D semimetallic HgTe is studied both theoretically and experimentally. The presence of e-h scattering leads to the friction between electrons and holes resulting in a large temperature-dependent contribution to the transport coefficients. The coefficient of friction between electrons and holes is determined. The comparison of experimental data with the theory shows that the interaction between electrons and holes based on the long-range Coulomb potential strongly underestimates the e-h friction. The experimental results are in agreement with the model of strong short-range e-h interaction.

  7. Down hole transmission system

    DOEpatents

    Hall, David R.; Hall, Jr., H. Tracy

    2007-07-24

    A transmission system in a downhole component comprises a data transmission element in both ends of the downhole component. Each data transmission element houses an electrically conducting coil in a MCEI circular trough. The electrically conducting coil comprises at least two generally fractional loops. In the preferred embodiment, the transmission elements are connected by an electrical conductor. Preferably, the electrical conductor is a coaxial cable. Preferably, the MCEI trough comprises ferrite. In the preferred embodiment, the fractional loops are connected by a connecting cable. In one aspect of the present invention, the connecting cable is a pair of twisted wires. In one embodiment the connecting cable is a shielded pair of twisted wires. In another aspect of the present invention, the connecting cable is a coaxial cable. The connecting cable may be disposed outside of the MCEI circular trough.

  8. 2D foam coarsening in a microfluidic system

    NASA Astrophysics Data System (ADS)

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

    2008-09-01

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

  9. Revealing high room and low temperatures mobilities of 2D holes in a strained Ge quantum well heterostructures grown on a standard Si(0 0 1) substrate

    NASA Astrophysics Data System (ADS)

    Myronov, Maksym; Morrison, Christopher; Halpin, John; Rhead, Stephen; Foronda, Jamie; Leadley, David

    2015-08-01

    Carrier mobility is one of the most important parameters of any semiconductor material, determining its suitability for applications in a large variety of electronic devices including field effect transistors (FETs). Today the capabilities of modern planar Si FET devices are almost exhausted and researchers are seeking either new device architectures or new materials. Here we report an extremely high room temperature (at 293 K) 2D hole gas (2DHG) drift mobility of 4500 cm2 V-1 s-1 at a carrier density of 1.2 × 1011 cm-2 obtained in a compressively strained Ge quantum well (QW) heterostructure, grown by an industrial type chemical vapor deposition system on a standard Si(0 0 1) substrate. The low-temperature Hall mobility and carrier density of this structure, measured at 333 mK, are 777,000 cm2 V-1 s-1 and 1.9 × 1011 cm-2, respectively. These hole mobilities are the highest not only among the group-IV Si and Ge based semiconductors, but also among p-type III-V and II-VI materials. The obtained room temperature mobility is substantially higher than those reported so far in strained Ge QW heterostructures and reveals a huge potential for further applications of this material in a wide variety of electronic devices.

  10. Potential role of CYP2D6 in the central nervous system

    PubMed Central

    Cheng, Jie; Zhen, Yueying; Miksys, Sharon; Beyoğlu, Diren; Krausz, Kristopher W.; Tyndale, Rachel F.; Yu, Aiming; Idle, Jeffrey R.; Gonzalez, Frank J.

    2013-01-01

    Cytochrome P450 2D6 (CYP2D6) is a pivotal enzyme responsible for a major human drug oxidation polymorphism in human populations. Distribution of CYP2D6 in brain and its role in serotonin metabolism suggest this CYP2D6 may have a function in central nervous system. To establish an efficient and accurate platform for the study of CYP2D6 in vivo, a transgenic human CYP2D6 (Tg-2D6) model was generated by transgenesis in wild-type C57BL/6 (WT) mice using a P1 phage artificial chromosome clone containing the complete human CYP2D locus, including CYP2D6 gene and 5’- and 3’- flanking sequences. Human CYP2D6 was expressed not only in the liver, but also in brain. The abundance of serotonin and 5-hydroxyindoleacetic acid in brain of Tg-2D6 is higher than in WT mice either basal levels or after harmaline induction. Metabolomics of brain homogenate and cerebrospinal fluid revealed a significant up-regulation of l-carnitine, acetyl-l-carnitine, pantothenic acid, dCDP, anandamide, N-acetylglucosaminylamine, and a down-regulation of stearoyl-l-carnitine in Tg-2D6 mice compared with WT mice. Anxiety tests indicate Tg-2D6 mice have a higher capability to adapt to anxiety. Overall, these findings indicate that the Tg-2D6 mouse model may serve as a valuable in vivo tool to determine CYP2D6-involved neurophysiological metabolism and function. PMID:23614566

  11. Upscaling of upward CO2 migration in 2D system

    NASA Astrophysics Data System (ADS)

    Behzadi, Hamid; Alvarado, Vladimir

    2012-09-01

    A procedure for upscaling CO2 buoyancy driven upward migration in finite-difference simulation models is presented in this work. This upscaling procedure accounts for capillary and buoyancy forces to enable CO2 upward migration modeling in coarser grids while accounting for dominant fine-scaled geological effects. The developed method is applied to 2D domains with no-flow boundary conditions. The absolute permeability field is correlated in the horizontal direction, with zero correlation in the vertical direction. Capillary pressure is parameterized using a Leveret J-function. A Dykstra-Parsons coefficient of 0.7 was used to generate a relatively heterogeneous absolute permeability field and hence test the developed algorithm under more stringent conditions. Multiphase flow upscaling is improved by accounting for spatial connectivity (percolation), which enables us to obtain more realistic rock-fluid pseudo-functions and capture effects of local capillary trapping at the fine scale (meso-scale trapping). The upscaling method and estimation of rock-fluid functions are numerically tested and compared with currently accepted single and multiphase flow upscaling methods. Results show that single-phase flow upscaling is insufficient, because it fails to adequately predict mobility and residual saturation, and hence multiphase flow upscaling should be employed. Significant improvement in gas travel time (representative of mobility) and trapped CO2 saturation (representative of trapped saturation) are observed when spatial connectivity (percolation) is included. The simulation execution time reduces 17-fold through upscaling. This speedup will enable simulating 3D CO2 sequestration simulation scenarios.

  12. 2-D isotropic negative refractive index in a N-type four-level atomic system

    NASA Astrophysics Data System (ADS)

    Zhao, Shun-Cai; Wu, Qi-Xuan; Ma, Kun

    2015-11-01

    2-D(Two-dimensional) isotropic negative refractive index (NRI) is explicitly realized via the orthogonal signal and coupling standing-wave fields coupling the Ntype four-level atomic system. Under some key parameters of the dense vapour media, the atomic system exhibits isotropic NRI with simultaneous negative permittivity and permeability (i.e. left-handedness) in the 2-D x-y plane. Compared with other 2-D NRI schemes, the coherent atomic vapour media in our scheme may be an ideal 2-D isotropic NRI candidate and has some potential advantages, significance or applications in the further investigation.

  13. Disorder-driven loss of phase coherence in a quasi-2D cold atom system

    NASA Astrophysics Data System (ADS)

    Beeler, M. C.; Reed, M. E. W.; Hong, T.; Rolston, S. L.

    2012-07-01

    We study the order parameter of a quasi-two-dimensional (quasi-2D) gas of ultracold atoms trapped in an optical potential in the presence of controllable disorder. Our results show that disorder drives phase fluctuations without significantly affecting the amplitude of the quasi-condensate order parameter. This is evidence that disorder can drive phase fluctuations in 2D systems, relevant to the phase-fluctuation mechanism for the superconductor-to-insulator phase transition (SIT) in disordered 2D superconductors.

  14. GAS DIFFUSION IN A 2-D SOIL SYSTEM

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chemical alternatives for methyl bromide appear to be the only viable short to medium range replacements in pre-plant soil fumigation systems. However, current fumigation practices need to be improved to minimize negative societal and environmental impacts. Often the amount of fumigant applied to so...

  15. Screening and transport in 2D semiconductor systems at low temperatures

    PubMed Central

    Das Sarma, S.; Hwang, E. H.

    2015-01-01

    Low temperature carrier transport properties in 2D semiconductor systems can be theoretically well-understood within RPA-Boltzmann theory as being limited by scattering from screened Coulomb disorder arising from random quenched charged impurities in the environment. In this work, we derive a number of analytical formula, supported by realistic numerical calculations, for the relevant density, mobility, and temperature range where 2D transport should manifest strong intrinsic (i.e., arising purely from electronic effects) metallic temperature dependence in different semiconductor materials arising entirely from the 2D screening properties, thus providing an explanation for why the strong temperature dependence of the 2D resistivity can only be observed in high-quality and low-disorder 2D samples and also why some high-quality 2D materials manifest much weaker metallicity than other materials. We also discuss effects of interaction and disorder on the 2D screening properties in this context as well as compare 2D and 3D screening functions to comment why such a strong intrinsic temperature dependence arising from screening cannot occur in 3D metallic carrier transport. Experimentally verifiable predictions are made about the quantitative magnitude of the maximum possible low-temperature metallicity in 2D systems and the scaling behavior of the temperature scale controlling the quantum to classical crossover. PMID:26572738

  16. Magnetotransport properties of 2D fermionic systems with k-cubic Rashba spin-orbit interaction

    NASA Astrophysics Data System (ADS)

    Mawrie, Alestin; Biswas, Tutul; Kanti Ghosh, Tarun

    2014-10-01

    The spin-orbit interaction in heavy hole gas formed at p-doped semiconductor heterojunctions and electron gas at SrTiO3 surfaces is cubic in momentum. Here we report magnetotransport properties of k-cubic Rashba spin-orbit coupled 2D fermionic systems. We study longitudinal and Hall components of the resistivity tensor analytically as well as numerically. The longitudinal resistivity shows a beating pattern due to different Shubnikov-de Haas (SdH) oscillation frequencies f± for spin-up and spin-down fermions. We propose empirical forms of f± as exact expressions are not available, which are being used to find locations of the beating nodes. The beating nodes and the number of oscillations between any two successive nodes obtained from exact numerical results are in excellent agreement with those calculated from the proposed empirical formula. In the Hall resistivity, an additional Hall plateau appears between the two conventional ones as the spin-orbit coupling constant increases. The width of this additional plateau increases with spin-orbit coupling constant.

  17. Novel exciton systems in 2D TMD monolayers and heterobilayers

    NASA Astrophysics Data System (ADS)

    Yu, Hongyi

    In this talk, two exciton systems in transition metal dichalcogenides (TMDs) monolayer and heterobilayer will be discussed. In TMD monolayers, the strong e-h Coulomb exchange interaction splits the exciton and trion dispersions into two branches with zero and finite gap, respectively. Each branch is a center-of-mass wave vector dependent coherent superposition of the two valleys, which leads to a valley-orbit coupling and possibly a trion valley Hall effect. The exchange interaction also eliminates the linear polarization of the negative trion PL emission. In TMD heterobilayers with a type-II band alignment, the low energy exciton has an interlayer configuration with the e and h localized in opposite layers. Because of the inevitable twist or/and lattice mismatch between the two layers, the bright interlayer excitons are located at finite center-of-mass velocities with a six-fold degeneracy. The corresponding photon emission is elliptically polarized, with the major axis locked to the direction of exciton velocity, and helicity determined by the valley indices of the e and h. Some experimental results on the interlayer excitons in the WSe2-MoSe2 heterobilayers will also be presented. The interlayer exciton exhibits a long lifetime as well as a long depolarization time, which facilitate the observation of a PL polarization ring pattern due to the valley dependent exciton-exciton interaction induced expansion. The works were supported by the Research Grant Council of Hong Kong (HKU17305914P, HKU705513P), the Croucher Foundation, and the HKU OYRA and ROP.

  18. GEO2D - Two-Dimensional Computer Model of a Ground Source Heat Pump System

    DOE Data Explorer

    James Menart

    2013-06-07

    This file contains a zipped file that contains many files required to run GEO2D. GEO2D is a computer code for simulating ground source heat pump (GSHP) systems in two-dimensions. GEO2D performs a detailed finite difference simulation of the heat transfer occurring within the working fluid, the tube wall, the grout, and the ground. Both horizontal and vertical wells can be simulated with this program, but it should be noted that the vertical wall is modeled as a single tube. This program also models the heat pump in conjunction with the heat transfer occurring. GEO2D simulates the heat pump and ground loop as a system. Many results are produced by GEO2D as a function of time and position, such as heat transfer rates, temperatures and heat pump performance. On top of this information from an economic comparison between the geothermal system simulated and a comparable air heat pump systems or a comparable gas, oil or propane heating systems with a vapor compression air conditioner. The version of GEO2D in the attached file has been coupled to the DOE heating and cooling load software called ENERGYPLUS. This is a great convenience for the user because heating and cooling loads are an input to GEO2D. GEO2D is a user friendly program that uses a graphical user interface for inputs and outputs. These make entering data simple and they produce many plotted results that are easy to understand. In order to run GEO2D access to MATLAB is required. If this program is not available on your computer you can download the program MCRInstaller.exe, the 64 bit version, from the MATLAB website or from this geothermal depository. This is a free download which will enable you to run GEO2D..

  19. Charge balancing in GaN-based 2-D electron gas devices employing an additional 2-D hole gas and its influence on dynamic behaviour of GaN-based heterostructure field effect transistors

    SciTech Connect

    Hahn, Herwig Reuters, Benjamin; Geipel, Sascha; Schauerte, Meike; Kalisch, Holger; Vescan, Andrei; Benkhelifa, Fouad; Ambacher, Oliver

    2015-03-14

    GaN-based heterostructure FETs (HFETs) featuring a 2-D electron gas (2DEG) can offer very attractive device performance for power-switching applications. This performance can be assessed by evaluation of the dynamic on-resistance R{sub on,dyn} vs. the breakdown voltage V{sub bd}. In literature, it has been shown that with a high V{sub bd}, R{sub on,dyn} is deteriorated. The impairment of R{sub on,dyn} is mainly driven by electron injection into surface, barrier, and buffer traps. Electron injection itself depends on the electric field which typically peaks at the gate edge towards the drain. A concept suitable to circumvent this issue is the charge-balancing concept which employs a 2-D hole gas (2DHG) on top of the 2DEG allowing for the electric field peak to be suppressed. Furthermore, the 2DEG concentration in the active channel cannot decrease by a change of the surface potential. Hence, beside an improvement in breakdown voltage, also an improvement in dynamic behaviour can be expected. Whereas the first aspect has already been demonstrated, the second one has not been under investigation so far. Hence, in this report, the effect of charge-balancing is discussed and its impact on the dynamic characteristics of HFETs is evaluated. It will be shown that with appropriate device design, the dynamic behaviour of HFETs can be improved by inserting an additional 2DHG.

  20. 2D and 3D Mechanobiology in Human and Nonhuman Systems.

    PubMed

    Warren, Kristin M; Islam, Md Mydul; LeDuc, Philip R; Steward, Robert

    2016-08-31

    Mechanobiology involves the investigation of mechanical forces and their effect on the development, physiology, and pathology of biological systems. The human body has garnered much attention from many groups in the field, as mechanical forces have been shown to influence almost all aspects of human life ranging from breathing to cancer metastasis. Beyond being influential in human systems, mechanical forces have also been shown to impact nonhuman systems such as algae and zebrafish. Studies of nonhuman and human systems at the cellular level have primarily been done in two-dimensional (2D) environments, but most of these systems reside in three-dimensional (3D) environments. Furthermore, outcomes obtained from 3D studies are often quite different than those from 2D studies. We present here an overview of a select group of human and nonhuman systems in 2D and 3D environments. We also highlight mechanobiological approaches and their respective implications for human and nonhuman physiology. PMID:27214883

  1. Dynamics and Control of a Reduced Order System of the 2-d Navier-Stokes Equations

    NASA Astrophysics Data System (ADS)

    Smaoui, Nejib; Zribi, Mohamed

    2014-11-01

    The dynamics and control problem of a reduced order system of the 2-d Navier-Stokes (N-S) equations is analyzed. First, a seventh order system of nonlinear ordinary differential equations (ODE) which approximates the dynamical behavior of the 2-d N-S equations is obtained by using the Fourier Galerkin method. We show that the dynamics of this ODE system transforms from periodic solutions to chaotic attractors through a sequence of bifurcations including a period doubling scenarios. Then three Lyapunov based controllers are designed to either control the system of ODEs to a desired fixed point or to synchronize two ODE systems obtained from the truncation of the 2-d N-S equations under different conditions. Numerical simulations are presented to show the effectiveness of the proposed controllers. This research was supported and funded by the Research Sector, Kuwait University under Grant No. SM02/14.

  2. Influence of elliptical shaped holes on the sensitivity and Q factor in 2D photonic crystals sensor

    NASA Astrophysics Data System (ADS)

    Benmerkhi, A.; Bouchemat, M.; Bouchemat, T.

    2016-07-01

    We theoretically investigate the refractive index sensor based on L2 photonic crystal cavity where neighboring holes are locally infiltrated with polymers. The photonic crystal is composed of periodic triangular hole array patterned perpendicularly to an InP-based confining heterostructure. The number of the holes surrounding a L2 cavity and their shape were modified in order to optimize the sensitivity and quality factor. From this study we have selected two structures that have good results. The first one is called locally which has a very high Q factor and a good sensitivity. Their values are 6.03 × 106 and 163 nm/RIU, respectively. The second optimized structure is called design B, which has a high sensitivity toward 227.78 nm/RIU with a Q factor of 5 × 105. The calculated detect limit for the two designs are lower than 1.59 × 10-6 and 1.4 × 10-5 RIU, respectively.

  3. Comparative study on 3D-2D convertible integral imaging systems

    NASA Astrophysics Data System (ADS)

    Choi, Heejin; Kim, Joohwan; Kim, Yunhee; Lee, Byoungho

    2006-02-01

    In spite of significant improvements in three-dimensional (3D) display fields, the commercialization of a 3D-only display system is not achieved yet. The mainstream of display market is a high performance two-dimensional (2D) flat panel display (FPD) and the beginning of the high-definition (HD) broadcasting accelerates the opening of the golden age of HD FPDs. Therefore, a 3D display system needs to be able to display a 2D image with high quality. In this paper, two different 3D-2D convertible methods based on integral imaging are compared and categorized for its applications. One method uses a point light source array and a polymer-dispersed liquid crystal and one display panel. The other system adopts two display panels and a lens array. The former system is suitable for mobile applications while the latter is for home applications such as monitors and TVs.

  4. High performance CCD camera system for digitalisation of 2D DIGE gels.

    PubMed

    Strijkstra, Annemieke; Trautwein, Kathleen; Roesler, Stefan; Feenders, Christoph; Danzer, Daniel; Riemenschneider, Udo; Blasius, Bernd; Rabus, Ralf

    2016-07-01

    An essential step in 2D DIGE-based analysis of differential proteome profiles is the accurate and sensitive digitalisation of 2D DIGE gels. The performance progress of commercially available charge-coupled device (CCD) camera-based systems combined with light emitting diodes (LED) opens up a new possibility for this type of digitalisation. Here, we assessed the performance of a CCD camera system (Intas Advanced 2D Imager) as alternative to a traditionally employed, high-end laser scanner system (Typhoon 9400) for digitalisation of differential protein profiles from three different environmental bacteria. Overall, the performance of the CCD camera system was comparable to the laser scanner, as evident from very similar protein abundance changes (irrespective of spot position and volume), as well as from linear range and limit of detection. PMID:27252121

  5. Design of FBG En/decoders in Coherent 2-D Time-polarization OCDMA Systems

    NASA Astrophysics Data System (ADS)

    Hou, Fen-fei; Yang, Ming

    2012-12-01

    A novel fiber Bragg grating (FBG)-based en/decoder for the two-dimensional (2-D) time-spreading and polarization multiplexer optical coding is proposed. Compared with other 2-D en/decoders, the proposed en/decoding for an optical code-division multiple-access (OCDMA) system uses a single phase-encoded FBG and coherent en/decoding. Furthermore, combined with reconstruction-equivalent-chirp technology, such en/decoders can be realized with a conventional simple fabrication setup. Experimental results of such en/decoders and the corresponding system test at a data rate of 5 Gbit/s demonstrate that this kind of 2-D FBG-based en/decoders could improve the performances of OCDMA systems.

  6. A multifunctional automated system of 2D laser polarimetry of biological tissues

    NASA Astrophysics Data System (ADS)

    Zabolotna, Natalia I.; Radchenko, Kostiantyn O.

    2014-09-01

    Multifunctional automated system of 2D laser polarimetry of biological tissues with enhanced functional capabilities is proposed. Two-layer optically thin (attenuation coefficient τ <= 0,1 ) biological structures, formed by "muscle tissue (MT) - the dermis of the skin (DS)" histological cryosections for the two physiological states (normal - dystrophy) were investigated. Complex of objective indexes which characterized by 2D polarization reproduced distributions under the following criteria: histograms of the distributions; statistical moments of the 1st - 4th order; autocorrelation functions; correlation moments; power spectra logarithmic dependencies of the distributions; fractal dimensions of the distributions; spectra moments are presented.

  7. 2-D PSD Diagnostic System for the Pellet Trajectory in LHD Plasmas

    NASA Astrophysics Data System (ADS)

    Hoshino, Mitsuyasu; Sakamoto, Ryuichi; Yamada, Hiroshi; Itoh, Yasuhiko; Kumagai, Kohki; Kumazawa, Ryuhei; Watari, Tetsuo; LHD Experimental Group

    Ablation of a solid hydrogen pellet in hot plasmas of Large Helical Device (LHD) has been studied. A position sensitive detector (PSD) diagnostics has been newly installed to measure the trajectory of ablating pellets. 2-D diagnostics enables the measurement with high time (1 MHz) and spatial resolutions (80 μm). A 3-D pellet trajectory can be described by a combination of 2-D images and information of initial pellet direction and velocity. A deflection of the pellet trajectory in the neutral beam injection (NBI) heated plasmas of LHD has been observed. Means of improving the measurement accuracy of this system are also discussed.

  8. Priority depth fusion for the 2D to 3D conversion system

    NASA Astrophysics Data System (ADS)

    Chang, Yu-Lin; Chen, Wei-Yin; Chang, Jing-Ying; Tsai, Yi-Min; Lee, Chia-Lin; Chen, Liang-Gee

    2008-02-01

    For the sake of providing 3D contents for up-coming 3D display devices, a real-time automatic depth fusion 2D-to-3D conversion system is needed on the home multimedia platform. We proposed a priority depth fusion algorithm with a 2D-to-3D conversion system which generates the depth map from most of the commercial video sequences. The results from different kinds of depth reconstruction methods are integrated into one depth map by the proposed priority depth fusion algorithm. Then the depth map and the original 2D image are converted to stereo images for showing on the 3D display devices. In this paper, a 2D-to-3D conversion algorithm set is combined with the proposed depth fusion algorithm to show the improved results. With the converted 3D contents, the needs for 3D display devices will also increase. As long as the two technologies evolve, the 3D-TV era will come as soon as possible.

  9. 2D and 3D Mass Transfer Simulations in β Lyrae System

    NASA Astrophysics Data System (ADS)

    Nazarenko, V. V.; Glazunova, L. V.; Karetnikov, V. G.

    2001-12-01

    2D and 3D mass transfer simulations of the mass transfer in β Lyrae binary system. We have received that from a point L3 40 per cent of mass transfer from L1-point is lost.The structure of a gas envelope, around system is calculated.3-D mass transfer simulations has shown presence the spiral shock in the disk around primary star's and a jet-like structures (a mass flow in vertical direction) over a stream.

  10. BILL2D - A software package for classical two-dimensional Hamiltonian systems

    NASA Astrophysics Data System (ADS)

    Solanpää, J.; Luukko, P. J. J.; Räsänen, E.

    2016-02-01

    We present BILL2D, a modern and efficient C++ package for classical simulations of two-dimensional Hamiltonian systems. BILL2D can be used for various billiard and diffusion problems with one or more charged particles with interactions, different external potentials, an external magnetic field, periodic and open boundaries, etc. The software package can also calculate many key quantities in complex systems such as Poincaré sections, survival probabilities, and diffusion coefficients. While aiming at a large class of applicable systems, the code also strives for ease-of-use, efficiency, and modularity for the implementation of additional features. The package comes along with a user guide, a developer's manual, and a documentation of the application program interface (API).

  11. A 2-D Microdisplay Using An Integrated Microresonating Waveguide Scanning System

    PubMed Central

    Hua, Wei-Shu; Tsui, Chi Leung; Soetanto, William; Wu, Wen-Jong; Wang, Wei-Chih

    2012-01-01

    Our research team has developed a MEMS based on a 2D micro image display device that can potentially overcome the size reduction limits while maintaining the high image resolution and field of view obtained by mirror based display systems. The basic design of the optical scanner includes a micro-fabricated polymer based cantilever waveguide that is electromechanically deflected by a 2D piezoelectric actuator. From the distal tip of the cantilever waveguide, a light beam is emitted and the direction of propagation is displaced along two orthogonal directions. The waveforms for the X-Y actuators and the LED light modulation are controlled using a field programmable gate array (FPGA). In this paper we will extend our display development by reporting more recent integration of components including actuators and light sources with a controller. Here we will describe the design, fabrication of the latest polymeric waveguide cantilever beam steering device driven by 2-D piezoelectric actuator using aerosol deposited PZT thick film actuators. The mechanical and optical design for the microresonating scanner will be discussed. In addition, the mechanical and optical performance of the 2-D scanner will be presented. PMID:26726320

  12. Parameterising root system growth models using 2D neutron radiography images

    NASA Astrophysics Data System (ADS)

    Schnepf, Andrea; Felderer, Bernd; Vontobel, Peter; Leitner, Daniel

    2013-04-01

    Root architecture is a key factor for plant acquisition of water and nutrients from soil. In particular in view of a second green revolution where the below ground parts of agricultural crops are important, it is essential to characterise and quantify root architecture and its effect on plant resource acquisition. Mathematical models can help to understand the processes occurring in the soil-plant system, they can be used to quantify the effect of root and rhizosphere traits on resource acquisition and the response to environmental conditions. In order to do so, root architectural models are coupled with a model of water and solute transport in soil. However, dynamic root architectural models are difficult to parameterise. Novel imaging techniques such as x-ray computed tomography, neutron radiography and magnetic resonance imaging enable the in situ visualisation of plant root systems. Therefore, these images facilitate the parameterisation of dynamic root architecture models. These imaging techniques are capable of producing 3D or 2D images. Moreover, 2D images are also available in the form of hand drawings or from images of standard cameras. While full 3D imaging tools are still limited in resolutions, 2D techniques are a more accurate and less expensive option for observing roots in their environment. However, analysis of 2D images has additional difficulties compared to the 3D case, because of overlapping roots. We present a novel algorithm for the parameterisation of root system growth models based on 2D images of root system. The algorithm analyses dynamic image data. These are a series of 2D images of the root system at different points in time. Image data has already been adjusted for missing links and artefacts and segmentation was performed by applying a matched filter response. From this time series of binary 2D images, we parameterise the dynamic root architecture model in the following way: First, a morphological skeleton is derived from the binary

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

    PubMed Central

    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

  14. Developing mobile BIM/2D barcode-based automated facility management system.

    PubMed

    Lin, Yu-Cheng; Su, Yu-Chih; 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

  15. Phase Transitions in Quasi-2D Plasma-Dust Systems: Simulations and Experiments

    NASA Astrophysics Data System (ADS)

    Petrov, Oleg; Vasiliev, Mikhail; Statsenko, Konstantin; Koss, Xeniya; Vasilieva, Elena; Myasnikov, Maxim; Lisin, Evgeny

    2015-11-01

    A nature of phase transition in quasi-2D dusty plasma structures was studied and the influence of the quasi-2D cluster size (a number of particles in it) on the features of the phase transition was investigated. Experiments and numerical simulation was conducted for the systems consisting of small (~ 10) and large (~ 103) number of particles. To investigate the phase state of the system with 7, 18 and 100 particles observed in numerical and laboratory experiments, we used the method based on analysis of dynamic entropy. Numerical modeling of small systems was conducted by the Langevin molecular dynamic method with the Langevin force, responsible for the stochastic nature of the motion of particles with a given kinetic temperature. Phase state of systems with the number of elements in the order of 103, was studied using the methods of statistical thermodynamics. Here we present new results of an experimental study of the change of translational and orientational order and topological defects, and the pair interactions at 2D melting of dust cluster in rf discharge plasma. The experimental results have revealed the existence of hexatic phase as well as solid-to-hexatic phase and hexatic-to-liquid transitions. This work was supported by the Russian Science Foundation (O.F. Petrov, M.M.Vasiliev, K.B. Stacenko, X.G. Koss, E.V. Vasilieva, M.I.Myasnikov and E.?.Lisin) through Grant No. 14-12-01440).

  16. Preliminary work of real-time ultrasound imaging system for 2-D array transducer.

    PubMed

    Li, Xu; Yang, Jiali; Ding, Mingyue; Yuchi, Ming

    2015-01-01

    Ultrasound (US) has emerged as a non-invasive imaging modality that can provide anatomical structure information in real time. To enable the experimental analysis of new 2-D array ultrasound beamforming methods, a pre-beamformed parallel raw data acquisition system was developed for 3-D data capture of 2D array transducer. The transducer interconnection adopted the row-column addressing (RCA) scheme, where the columns and rows were active in sequential for transmit and receive events, respectively. The DAQ system captured the raw data in parallel and the digitized data were fed through the field programmable gate array (FPGA) to implement the pre-beamforming. Finally, 3-D images were reconstructed through the devised platform in real-time. PMID:26405923

  17. Delay-dependent stability and stabilisation of continuous 2D delayed systems with saturating control

    NASA Astrophysics Data System (ADS)

    Hmamed, Abdelaziz; Kririm, Said; Benzaouia, Abdellah; Tadeo, Fernando

    2016-09-01

    This paper deals with the stabilisation problem of continuous two-dimensional (2D) delayed systems, in the presence of saturations on the control signals. For this, a new delay decomposition approach is proposed to deal with the stability and stabilisation issues. The idea is that the range of variation of each delay is divided into segments, and a specific Lyapunov- Krasovskii functional is used that contains different weight matrices in each segment. Then, based on this approach, new delay-dependent stability and stabilisation criteria for continuous 2D delayed systems are derived. These criteria are less conservative and include some existing results as special cases. Some numerical examples are provided to show that a significant improvement is achieved using the proposed approach.

  18. The potential energy surface and chaos in 2D Hamiltonian systems

    NASA Astrophysics Data System (ADS)

    Li, Jiangdan; Zhang, Suying

    2011-02-01

    We provide a new insight into the relationship between the geometric property of the potential energy surface and chaotic behavior of 2D Hamiltonian dynamical systems, and give an indicator of chaos based on the geometric property of the potential energy surface by defining Mean Convex Index (MCI). We also discuss a model of unstable Hamiltonian in detail, and show our results in good agreement with HBLSL's (Horwitz, Ben Zion, Lewkowicz, Schiffer and Levitan) new Riemannian geometric criterion.

  19. Interaction of water molecules with hexagonal 2D systems. A DFT study

    NASA Astrophysics Data System (ADS)

    Rojas, Ángela; Rey, Rafael

    Over the years water sources have been contaminated with many chemical agents, becoming issues that affect health of the world population. The advances of the nanoscience and nanotechnology in the development new materials constitute an alternative for design molecular filters with great efficiencies and low cost for water treatment and purification. In the nanoscale, the process of filtration or separation of inorganic and organic pollutants from water requires to study interactions of these atoms or molecules with different nano-materials. Specifically, it is necessary to understand the role of these interactions in physical and chemical properties of the nano-materials. In this work, the main interest is to do a theoretical study of interaction between water molecules and 2D graphene-like systems, such as silicene (h-Si) or germanene (h-Ge). Using Density Functional Theory we calculate total energy curves as function of separation between of water molecules and 2D systems. Different spatial configurations of water molecules relative to 2D systems are considered. Structural relaxation effects and changes of electronic charge density also are reported. Universidad Nacional de Colombia.

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

    NASA Astrophysics Data System (ADS)

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

    2004-11-01

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

  1. Strong and Weak 2D Topological Superconductivity in Hidden Quasi-1D Systems

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Yao, Hong

    2014-03-01

    Partly motivated by the newly discovered family of bismuth-based superconductors including LaO1-xFxBiS2, we study possible 2D topological superconductivities (TSC) in hidden quasi-1D systems with spin-orbit couplings. By doing RPA calculations and renormalization group (RG) treatment, we theoretically find that in a large portion of the phase diagram with varying interaction strengths and spin-orbit coupling the ground states favors superconductivity with odd-parity pairing, which results in either chiral TSC or time reversal invariant weak-Z2 TSC. We shall discuss several ways to experimentally identify these strong and weak 2D topological superconductivity. Possible applications to the bismuth-based superconductors LaO1-xFxBiS2 will also be remarked.

  2. Numerical studies of the melting transition in 2D Yukawa systems

    SciTech Connect

    Hartmann, P.; Donko, Z.; Kalman, G. J.

    2008-09-07

    We present the latest results of our systematic studies of the solid--liquid phase transition in 2D classical many-particle systems interacting with the Yukawa potential. Our previous work is extended by applying the molecular dynamic simulations to systems with up to 1.6 million particles in the computational box (for {kappa} = 2 case). Equilibrium simulations are performed for different coupling parameters in the vicinity of the expected melting transition ({gamma}{sub m}{sup {kappa}}{sup ={sup 2}}{approx_equal}415) and a wide range of observables are averaged over uncorrelated samples of the micro-canonical ensemble generated by the simulations.

  3. FPGA implementation of 2-D discrete cosine transforms algorithm using systemC

    NASA Astrophysics Data System (ADS)

    Liu, Yifei; Ding, Mingyue

    2007-12-01

    Discrete Cosine Transform (DCT) is widely applied in image and video compression. This paper presented the software and hardware co-design method based on SystemC. As a case of study, a two dimension (2D) DCT Algorithm was implemented on Programmable Gate Arrays (FPGAs) chip. The short simulation time and verification process greatly increases the design efficiency of SystemC, making the product designed by SystemC more quickly into the market. The design effect using SystemC is compared between the expertise hardware designer and the software designer with little hardware knowledge. The result shows SystemC is an excellent and high efficiency hardware design method for an expertise hardware designer.

  4. Corner transfer matrices for 2D strongly coupled many-body Floquet systems

    NASA Astrophysics Data System (ADS)

    Kukuljan, Ivan; Prosen, Tomaž

    2016-04-01

    We develop, based on Baxter’s corner transfer matrices, a renormalizable numerically exact method for computation of the level density of the quasienergy spectra of two-dimensional (2D) locally interacting many-body Floquet systems. We demonstrate its functionality exemplified by the kicked 2D quantum Ising model. Using the method, we are able to treat systems of arbitrarily large finite size (for example lattices of the order of 108 spins). We clearly demonstrate that the density of the Floquet quasienergy spectrum tends to a flat function in the thermodynamic limit for generic values of model parameters. However, contrary to the prediction of random matrices of the circular orthogonal ensemble, the decay rates of the Fourier coefficients of the Floquet level density exhibit rich and non-trivial dependence on the system’s parameters. Remarkably, we find that the method is renormalizable and gives thermodynamically convergent results only in certain regions of the parameter space where the corner transfer matrices have effectively a finite rank for any system size. In the complementary regions, the corner transfer matrices effectively become of full rank and the method becomes non-renormalizable. This may indicate an interesting phase transition from an area- to volume-law of entanglement in the thermodynamic state of a Floquet system.

  5. Microwave tomography of extremities: 1. Dedicated 2D system and physiological signatures

    NASA Astrophysics Data System (ADS)

    Semenov, Serguei; Kellam, James; Sizov, Yuri; Nazarov, Alexei; Williams, Thomas; Nair, Bindu; Pavlovsky, Andrey; Posukh, Vitaly; Quinn, Michael

    2011-04-01

    Microwave tomography (MWT) is a novel imaging modality which might be applicable for non-invasive assessment of functional and pathological conditions of biological tissues. Imaging of the soft tissue of extremities is one of its potential applications. The feasibility of this technology for such applications was demonstrated earlier. This is the first of two companion papers focused on an application of MWT for imaging of the extremity's soft tissues. The goal of this study is to assess the technical performance of the developed 2D MWT system dedicated for imaging of functional and pathological conditions of the extremity's soft tissues. Specifically, the system's performance was tested by its ability to detect signals associated with physiological activity and soft tissue interventions (circulatory related changes, blood flow reduction and a simulated compartmental syndrome)—the so-called physiological signatures. The developed 2D MWT system dedicated to the imaging of animal extremities demonstrates good technical performance allowing for stable and predictable data acquisition with reasonable agreement between the experimentally measured electromagnetic (EM) field and the simulated EM field within a measurement domain. Using the system, we were able to obtain physiological signatures associated with systolic versus diastolic phases of circulation in an animal extremity, reperfusion versus occlusion phases of the blood supply to the animal's extremity and a compartment syndrome. The imaging results are presented and discussed in the second companion paper.

  6. Microwave tomography of extremities: 1. Dedicated 2D system and physiological signatures.

    PubMed

    Semenov, Serguei; Kellam, James; Sizov, Yuri; Nazarov, Alexei; Williams, Thomas; Nair, Bindu; Pavlovsky, Andrey; Posukh, Vitaly; Quinn, Michael

    2011-04-01

    Microwave tomography (MWT) is a novel imaging modality which might be applicable for non-invasive assessment of functional and pathological conditions of biological tissues. Imaging of the soft tissue of extremities is one of its potential applications. The feasibility of this technology for such applications was demonstrated earlier. This is the first of two companion papers focused on an application of MWT for imaging of the extremity's soft tissues. The goal of this study is to assess the technical performance of the developed 2D MWT system dedicated for imaging of functional and pathological conditions of the extremity's soft tissues. Specifically, the system's performance was tested by its ability to detect signals associated with physiological activity and soft tissue interventions (circulatory related changes, blood flow reduction and a simulated compartmental syndrome)--the so-called physiological signatures. The developed 2D MWT system dedicated to the imaging of animal extremities demonstrates good technical performance allowing for stable and predictable data acquisition with reasonable agreement between the experimentally measured electromagnetic (EM) field and the simulated EM field within a measurement domain. Using the system, we were able to obtain physiological signatures associated with systolic versus diastolic phases of circulation in an animal extremity, reperfusion versus occlusion phases of the blood supply to the animal's extremity and a compartment syndrome. The imaging results are presented and discussed in the second companion paper. PMID:21364265

  7. Electron phase coherent effects in nanostructures and coupled 2D systems

    SciTech Connect

    Simmons, J.A.; Lyo, S.K.; Klem, J.F.; Sherwin, M.E.; Harff, N.E.; Eiles, T.M.; Wendt, J.R.

    1995-05-01

    This report describes the research accomplishments achieved under the LDRD Project ``Electron Phase Coherent Effects in Nanostructures and Coupled 2D Systems.`` The goal of this project was to discover and characterize novel quantum transport phenomena in small semiconductor structures at low temperatures. Included is a description of the purpose of the research, the various approaches used, and a detailed qualitative description of the numerous new results obtained. The first appendix gives a detailed listing of publications, presentations, patent applications, awards received, and various other measures of the LDRD project success. Subsequent appendices consist of reprinted versions of several specific,`` scientific journal publications resulting from this LDRD project.

  8. The evaluation system of the 2-D scanning mirror based on CMOS sensor

    NASA Astrophysics Data System (ADS)

    Zeng, Gui-ying; Xie, Yuan; Chen, Jin-xing

    2010-10-01

    The high precision two-dimension scanning control technique is being developed for the next geosynchronous satellites FY-4 satellites which is using the three-axis stabilization stages. How to evaluate the point and scanning precision of the scanning mirror is one of the most important technologies. This paper describes the optoelectronic measure method based on CMOS sensors to evaluate the point and scanning precision of the scanning mirror in the laboratory, which is a 2-D dynamic angle measurement system. Some technologies, such as the sup-pixel orientation technology and the CMOS ROI technology, are used in the measurement system. The research shows that the angle measurement system based on IBIS-6600CMOS sensors can attain the 20°× 20° field of view, 2" accuracy, and 1Kframes/s speed. But the system is sensitive to the environment and it can only be worked in the laboratory.

  9. Image compression-encryption scheme based on hyper-chaotic system and 2D compressive sensing

    NASA Astrophysics Data System (ADS)

    Zhou, Nanrun; Pan, Shumin; Cheng, Shan; Zhou, Zhihong

    2016-08-01

    Most image encryption algorithms based on low-dimensional chaos systems bear security risks and suffer encryption data expansion when adopting nonlinear transformation directly. To overcome these weaknesses and reduce the possible transmission burden, an efficient image compression-encryption scheme based on hyper-chaotic system and 2D compressive sensing is proposed. The original image is measured by the measurement matrices in two directions to achieve compression and encryption simultaneously, and then the resulting image is re-encrypted by the cycle shift operation controlled by a hyper-chaotic system. Cycle shift operation can change the values of the pixels efficiently. The proposed cryptosystem decreases the volume of data to be transmitted and simplifies the keys distribution simultaneously as a nonlinear encryption system. Simulation results verify the validity and the reliability of the proposed algorithm with acceptable compression and security performance.

  10. Development of 2D Microdisplay Using an Integrated Microresonating Waveguide Scanning System.

    PubMed

    Hua, Wei-Shu; Wang, Wei-Chih; Wu, Wen-Jong; Tsui, Chi Leung; Cui, Wei; Shih, Wen-Pin

    2011-09-01

    Our research team has developed a 2D micro image display device that can potentially overcome the size reduction limits while maintaining the high-image resolution and field of view obtained by mirror-based display systems. The basic design of the optical scanner includes a microfabricated SU-8 cantilever waveguide that is electromechanically deflected by a piezoelectric actuator. From the distal tip of the cantilever waveguide, a light beam is emitted and the direction of propagation is displaced along two orthogonal directions. The waveforms for the actuator and the LED light modulation are generated and controlled using a field programmable gate array. Our recent study is an update to the previously-reported mechanical scanner, replacing the hand-built PZT scanner and fiber waveguide with a microfabricated system incorporating aerosol-deposited PZT thin film and a polymeric SU-8 wave guide. In this article, we report on the design and fabrication of a prototype miniaturized 2D scanner, discuss optical and mechanical the modeling of the system's properties and present the experimental results. PMID:22876080

  11. Microwave tomography of extremities: 1) Dedicated 2D system and physiological signatures

    PubMed Central

    Semenov, Serguei; Kellam, James; Sizov, Yuri; Nazarov, Alexei; Williams, Thomas; Nair, Bindu; Pavlovsky, Andrey; Posukh, Vitaly; Quinn, Michael

    2011-01-01

    Microwave Tomography (MWT) is a novel imaging modality which might be applicable for non-invasive assessment of functional and pathological conditions of biological tissues. The imaging of the soft tissue of extremities is one of its potential applications. The feasibility of this technology for such applications was demonstrated earlier. This is the first of two companion papers focused on an application of MWT for imaging of the extremity’s soft tissues. The goal of this study is to assess the technical performance of the developed 2D MWT system dedicated for imaging of functional and pathological conditions of the extremity’s soft tissues. Specifically, the system’s performance was tested by its ability to detect signals associated with physiological activity and soft tissue interventions (circulatory related changes, blood flow reduction and a simulated compartmental syndrome) – so called “physiological signatures”. The developed 2D MWT system dedicated for an imaging of animal extremities demonstrates good technical performance allowing for stable and predictable data acquisition with reasonable agreement between experimentally measured electromagnetic (EM) field and simulated EM field within a measurement domain. Using the system we were able to obtain physiological signatures associated with systolic vs diastolic phases of circulation in an animal extremity, reperfusion vs occlusion phases of the blood supply to the animal’s extremity and the a compartment syndrome. The imaging results are presented and discussed in the second companion paper. PMID:21364265

  12. Spanning graphene to carbon-nitride: A 2-D semiconductor alloy system of carbon and nitrogen

    NASA Astrophysics Data System (ADS)

    Therrien, Joel; Li, Yancen; Schmidt, Daniel

    2014-03-01

    With the explosion of materials that form 2-D structures in the past few years, there have been a much more diverse ecosystem of combinations of characteristics to explore. Yet with the majority of materials investigated, the properties are fixed according to the composition of the material. Ideally, one wishes to have a tunable system similar to the semiconductor alloy systems, such as AlxGa1-xAs. There have been some theoretical studies of transition metal dichalogenides, none have been reported experimentally as of this writing. The tertianary alloy of BCN has been synthesized, however it was found that the boron had the tendency to cause phase segregation of the material into domains of graphene and boron nitride. Here we will report on the synthesis of non-phase seperated carbon-nitrogen 2D alloys ranging from graphene (Eg = 0 eV) to carbon-nitride, or melon, (Eg = 2.7 eV). We will report on synthesis methods and a summary of relevant electronic and material properties of selected alloys.

  13. Schrödinger equation for non-pure dipole potential in 2D systems

    NASA Astrophysics Data System (ADS)

    Moumni, M.; Falek, M.

    2016-07-01

    In this work, we analytically study the Schrödinger equation for the (non-pure) dipolar ion potential V(r) = q/r + Dcosθ/r2, in the case of 2D systems (systems in two-dimensional Euclidean plane) using the separation of variables and the Mathieu equations for the angular part. We give the expressions of eigenenergies and eigenfunctions and study their dependence on the dipole moment D. Imposing the condition of reality on the energies En,m implies that the dipole moment must not exceed a maximum value, otherwise the corresponding bound state disappears. We also find that the s states (m = 0) can no longer exist in the system as soon as the dipole term is present.

  14. Radiometer uncertainty equation research of 2D planar scanning PMMW imaging system

    NASA Astrophysics Data System (ADS)

    Hu, Taiyang; Xu, Jianzhong; Xiao, Zelong

    2009-07-01

    With advances in millimeter-wave technology, passive millimeter-wave (PMMW) imaging technology has received considerable concerns, and it has established itself in a wide range of military and civil practical applications, such as in the areas of remote sensing, blind landing, precision guidance and security inspection. Both the high transparency of clothing at millimeter wavelengths and the spatial resolution required to generate adequate images combine to make imaging at millimeter wavelengths a natural approach of screening people for concealed contraband detection. And at the same time, the passive operation mode does not present a safety hazard to the person who is under inspection. Based on the description to the design and engineering implementation of a W-band two-dimensional (2D) planar scanning imaging system, a series of scanning methods utilized in PMMW imaging are generally compared and analyzed, followed by a discussion on the operational principle of the mode of 2D planar scanning particularly. Furthermore, it is found that the traditional radiometer uncertainty equation, which is derived from a moving platform, does not hold under this 2D planar scanning mode due to the fact that there is no absolute connection between the scanning rates in horizontal direction and vertical direction. Consequently, an improved radiometer uncertainty equation is carried out in this paper, by means of taking the total time spent on scanning and imaging into consideration, with the purpose of solving the problem mentioned above. In addition, the related factors which affect the quality of radiometric images are further investigated under the improved radiometer uncertainty equation, and ultimately some original results are presented and analyzed to demonstrate the significance and validity of this new methodology.

  15. Avalanches in 2D Dislocation Systems: Plastic Yielding Is Not Depinning

    NASA Astrophysics Data System (ADS)

    Ispánovity, Péter Dusán; Laurson, Lasse; Zaiser, Michael; Groma, István; Zapperi, Stefano; Alava, Mikko J.

    2014-06-01

    We study the properties of strain bursts (dislocation avalanches) occurring in two-dimensional discrete dislocation dynamics models under quasistatic stress-controlled loading. Contrary to previous suggestions, the avalanche statistics differ fundamentally from predictions obtained for the depinning of elastic manifolds in quenched random media. Instead, we find an exponent τ =1 of the power-law distribution of slip or released energy, with a cutoff that increases exponentially with the applied stress and diverges with system size at all stresses. These observations demonstrate that the avalanche dynamics of 2D dislocation systems is scale-free at every applied stress and, therefore, cannot be envisaged in terms of critical behavior associated with a depinning transition.

  16. Robust H(∞) control for a class of 2-D discrete delayed systems.

    PubMed

    Ye, Shuxia; Li, Jianzhen; Yao, Juan

    2014-09-01

    In this paper, we deal with the problem of robust H∞ control for a class of 2-D discrete uncertain systems with delayed perturbations described by the Roesser state-space model (RM). The problem to be addressed is the design of robust controllers via state feedback such that the stability of the resulting closed-loop system is guaranteed and a prescribed H∞ performance level is ensured for all delayed perturbations. By utilizing the Lyapunov method and some results, H∞ controllers are given. The results are delay-dependent and can be expressed in terms of linear matrix inequalities (LMIs). Finally, some numerical examples are given to illustrate the effectiveness of the proposed results. PMID:24411024

  17. Engagement of neural circuits underlying 2D spatial navigation in a rodent virtual reality system

    PubMed Central

    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

  18. Automatic angle measurement of a 2D object using optical correlator-neural networks hybrid system

    NASA Astrophysics Data System (ADS)

    Manivannan, N.; Neil, M. A. A.

    2011-04-01

    In this paper a novel method is proposed and demonstrated for automatic rotation angle measurement of a 2D object using a hybrid architecture, consisting of a 4f optical correlator with a binary phase only multiplexed matched filter and a single layer neural network. The hybrid set-up can be considered as a two-layer perceptron-like neural network; an optical correlator is the first layer and the standard single layer neural network is the second layer. The training scheme used to train the hybrid architecture is a combination of a Direct Binary Search algorithm, to train the optical correlator, and an Error Back Propagation algorithm, to train the neural network. The aim is to perform the major information processing by the optical correlator with a small additional processing by the neural network stage. This allows the system to be used for real-time applications as optics has the inherent ability to process information in a parallel manner at high speed. The neural network stage gives an extra dimension of freedom so that complicated tasks like automatic rotation angle measurement can be achieved. Results of both computer simulation and experimental set-up are presented for rotation angle measurement of an English alphabetic character as a 2D object. The experimental set-up consists of a real optical correlator using two spatial light modulators for both input and frequency plane representations and a PC based model of a single layer network.

  19. Phase Diagram of Bilayer 2D Electron Systems at νT = 1

    NASA Astrophysics Data System (ADS)

    Champagne, Alexandre

    2009-03-01

    Bilayer 2D electron systems at total filling fraction νT = 1 and small interlayer spacing can support a strongly correlated phase which exhibits spontaneous interlayer phase coherence and may be described as an excitonic Bose condensate. We use electron interlayer tunnelling and transport to explore the phase diagram of bilayer 2D electron systems at νT = 1, and find that phase transitions between the excitonic νT = 1 phase and bilayer states which lack significant interlayer correlations can be induced in three different ways: by increasing the effective interlayer spacing, d/l, the temperature, T, or the charge imbalance, δν=ν1-ν2. First, for the balanced (δν = 0) system we find that the amplitude of the resonant tunneling in the coherent νT = 1 phase obeys an empirical power law scaling versus d/l at various T, and the layer separation where the tunneling disappears scales linearly with T. Our results [1] offer strong evidence that a finite temperature phase transition separates the balanced interlayer coherent phase from incoherent phases which lack strong interlayer correlations. Secondly, we observe [2] that close to the phase boundary the coherent νT = 1 phase can be absent at δν = 0, present at intermediate δν, and absent again at large δν, thus indicating an intricate phase competition between it and incoherent quasi-independent layer states. Lastly, at δν = 1/3 we report [2] the observation of a direct phase transition between the coherent νT = 1 bilayer integer quantum Hall phase and the pair of single layer fractional quantized Hall states at ν1 = 2/3 and ν2 = 1/3.[4pt] [1] A.R. Champagne, et al., Phys. Rev. Lett. 100, 096801 (2008).[0pt] [2] A.R. Champagne, et al, Phys. Rev. B 78, 205310 (2008)

  20. Formation of a helical channel in a 2D system in a quantum Hall regime

    NASA Astrophysics Data System (ADS)

    Kazakov, Aleksandr; Kolkovsky, V.; Adamus, Z.; Karczewski, G.; Wojtowicz, T.; Rokhinson, Leonid

    A two-dimensional system with reconfigurable network of one-dimensional p-wave superconducting channels is a perfect platform to perform braiding of non-Abelian excitations. Such channels can be realized in CdTe:Mn quantum wells in a quantum Hall effect regime, where counterpropagaring edge states with opposite spin polarization can be formed by electrostatic gating. These edges form helical channels similar to the edges of 2D topological insulators and, coupled to a superconductor, should support non-Abelian excitations. While long channels are localized at low temperatures, we found that resistance in short (<6 μm) helical channels remains finite at low temperatures. Transport data and resistance scaling with channel length will be presented. Work supported by ONR, National Science Centre (Poland) and Foundation for Polish Science.

  1. Calibration of an Ultrasound Tomography System for Medical Imaging with 2D Contrast-Source Inversion

    NASA Astrophysics Data System (ADS)

    Faucher, Gabriel Paul

    This dissertation describes two possible methods for the calibration of an ultrasound tomography system developed at University of Manitoba's Electromagnetic Imaging Laboratory for imaging with the contrast-source inversion algorithm. The calibration techniques are adapted from existing procedures employed for microwave tomography. A theoretical model of these calibration principles is developed in order to provide a rationale for the effectiveness of the proposed procedures. The applicability of such an imaging algorithm and calibration methods in the context of ultrasound are discussed. Also presented are 2D and 3D finite-difference time-domain update equations for the simulation of acoustic wave propagation in inhomogeneous media. Details regarding the application of an absorbing boundary-condition, point-source modelling and the treatment of penetrable objects are included in this document.

  2. The stability of freely-propagating ion acoustic waves in 2D systems

    NASA Astrophysics Data System (ADS)

    Chapman, Thomas; Berger, Richard; Banks, Jeffrey; Brunner, Stephan

    2014-10-01

    The stability of a freely-propagating ion acoustic wave (IAW) is a basic science problem that is made difficult by the need to resolve electron kinetic effects over a timescale that greatly exceeds the IAW period during numerical simulation. Recent results examining IAW stability using a 1D+1V Vlasov-Poisson solver indicate that instability is a fundamental property of IAWs that occurs over most if not all of the parameter space of relevance to ICF experiments. We present here new results addressing the fundamental question of IAW stability across a broad range of plasma conditions in a 2D+2V system using LOKI, ranging from a regime of relatively weak to a regime of relatively strong ion kinetic effects. Work performed under the auspices of the U.S. DOE by LLNL (DE-AC52-07NA27344) and funded by the LDRD Program at LLNL (12-ERD-061).

  3. Stress dynamics of a 2D dense granular system near shear jamming

    NASA Astrophysics Data System (ADS)

    Ren, Jie; Dijksman, Joshua; Behringer, Robert

    2013-03-01

    We study the dynamics of pressure and shear stress in a frictional 2D dense granular system using a novel apparatus that can provide fixed-volume shear without generating inhomogeneities. Under increasing shear strain, the system's pressure shows a strong increase with strain, characterized by a ``Reynolds coefficient,'' R =d2 P / dγ2 . R depends only on packing fraction ϕ, and shows a strong increase as ϕ approaches ϕJ from below. In the meantime, the system's shear stress shows a non-monotonic behavior with increasing strain. It first increases with strain as the system is in ``fragile'' states and builds up long force chains along the compression direction. After a certain amount of strain, force chains along the dilation direction starts to build up, and the system transfers into a ``shear-jammed'' state and the shear stress starts to decrease with strain. Under oscillatory shear, both pressure and shear stress show limit-cycle behavior and reach steady states after many cycles. However, the limit cycles of pressure and shear stress are very different: the pressure exhibits a hysteresis-free parabolic curve, while the shear stress exhibits a strongly hysteretic loop. This work is funded by NSF grants: DMR0906908, DMS0835571, NASA grant NNX10AU01G and ARO grant W911NF-11-1-0110.

  4. Multichannel reconfigurable measurement system for hot plasma diagnostics based on GEM-2D detector

    NASA Astrophysics Data System (ADS)

    Wojenski, A. J.; Kasprowicz, G.; Pozniak, K. T.; Byszuk, A.; Chernyshova, M.; Czarski, T.; Jablonski, S.; Juszczyk, B.; Zienkiewicz, P.

    2015-12-01

    In the future magnetically confined fusion research reactors (e.g. ITER tokamak), precise determination of the level of the soft X-ray radiation of plasma with temperature above 30 keV (around 350 mln K) will be very important in plasma parameters optimization. This paper presents the first version of a designed spectrography measurement system. The system is already installed at JET tokamak. Based on the experience gained from the project, the new generation of hardware for spectrography measurements, was designed and also described in the paper. The GEM detector readout structure was changed to 2D in order to perform measurements of i.e. laser generated plasma. The hardware structure of the system was redesigned in order to provide large number of high speed input channels. Finally, this paper also covers the issue of new control software, necessary to set-up a complete system of certain complexity and perform data acquisition. The main goal of the project was to develop a new version of the system, which includes upgraded structure and data transmission infrastructure (i.e. handling large number of measurement channels, high sampling rate).

  5. Caracterisation pratique des systemes quantiques et memoires quantiques auto-correctrices 2D

    NASA Astrophysics Data System (ADS)

    Landon-Cardinal, Olivier

    approche, dite de tomographie variationnelle, propose de reconstruire l'etat en restreignant l'espace de recherche a une classe variationnelle plutot qu'a l'immense espace des etats possibles. Un etat variationnel etant decrit par un petit nombre de parametres, un petit nombre d'experiences peut suffire a identifier les parametres variationnels de l'etat experimental. Nous montrons que c'est le cas pour deux classes variationnelles tres utilisees, les etats a produits matriciels (MPS) et l'ansatz pour intrication multi-echelle (MERA). Memoires quantiques auto-correctrices 2D. Une memoire quantique auto-correctrice est un systeme physique preservant de l'information quantique durant une duree de temps macroscopique. Il serait done l'equivalent quantique d'un disque dur ou d'une memoire flash equipant les ordinateurs actuels. Disposer d'un tel dispositif serait d'un grand interet pour l'informatique quantique. Une memoire quantique auto-correctrice est initialisee en preparant un etat fondamental, c'est-a-dire un etat stationnaire de plus basse energie. Afin de stocker de l'information quantique, il faut plusieurs etats fondamentaux distincts, chacun correspondant a une valeur differente de la memoire. Plus precisement, l'espace fondamental doit etre degenere. Dans cette these, on s'interesse a des systemes de particules disposees sur un reseau bidimensionnel (2D), telles les pieces sur un echiquier, qui sont plus faciles a realiser que les systemes 3D. Nous identifions deux criteres pour l'auto-correction: - La memoire quantique doit etre stable face aux perturbations provenant de l'environnement, par exemple l'application d'un champ magnetique externe. Ceci nous amene a considerer les systemes topologiques 2D dont les degres de liberte sont intrinsequement robustes aux perturbations locales de l'environnement. - La memoire quantique doit etre robuste face a un environnement thermique. Il faut s'assurer que les excitations thermiques n'amenent pas deux etats fondamentaux

  6. Propagating fronts in 2D Cr(OH) 3 precipitate systems in gelled media

    NASA Astrophysics Data System (ADS)

    Sultan, Rabih; Panjarian, Shoghag

    2001-09-01

    Diffusion fronts propagate as two co-precipitate ions inter-diffuse in a gel medium. Liesegang bands of precipitate form periodically behind the diffusion front of an outer electrolyte. The precipitation of Cr(OH) 3 from NaOH diffusing into a Cr 3+ gel matrix is known to yield a single band that propagates in a one-dimensional (1D) tube - Cr(OH) 3 dissolves in excess OH - forming Cr(OH) 4-. We perform similar experiments on the Cr(OH) 3 system in two dimensions (2D), wherein we obtain a perfectly circular Cr(OH) 3 ring that grows larger and thicker as time advances. Using a specially designed Petri dish, ring propagation is monitored both in the absence and the presence of a constant electric field. The field is applied along a radial direction, and the front velocities with the field on are compared with the field-free case. When the field is applied against the direction of front propagation (“negative” field), wave saturation is obtained, characterized by a slight increase in the velocity of propagation with field strength, until it reaches a constant value as the field strength is further increased. In a positive field situation, the wave velocity increases with field strength and exhibits some other interesting features: (1) wave stopping indicated by a freeze in the ring position at a certain characteristic time; (2) annihilation of the ring formation above a critical value of the field strength. Electrical effects in 2D are also studied when electrodes with different potentials are planted at various locations in the electrolyte periphery. Interesting patterning structures including the distortion of the circular symmetry and the birth of multiple rings are reported.

  7. Controlling the Dynamics of the Five-Mode Truncation System of the 2-d Navier-Stokes Equations

    NASA Astrophysics Data System (ADS)

    Smaoui, Nejib; Zribi, Mohamed

    2015-11-01

    The dynamics and the control problem of the two dimensional (2-d) Navier-Stokes (N-S) equations with spatially periodic and temporally steady forcing is addressed. At first, the Fourier Galerkin method is applied to the 2-d N-S equations to obtain a fifth order system of nonlinear ordinary differential equations (ODE) that approximates the behavior of these equations. Simulation studies indicate that the obtained ODE system captures the behavior of the 2-d N-S equations. Then, a control law is proposed to drive the states of the ODE system to a desired fixed point. Next, a second control law is developed to synchronize two reduced order ODE models of the 2-d N-S equations having the same Reynolds number and starting from different initial conditions. Finally, simulation results are undertaken to validate the theoretical developments. This research was supported and funded by the Research Sector, Kuwait University under Grant No. SM 05/15.

  8. Comparison of Failure Modes in 2-D and 3-D Woven Carbon Phenolic Systems

    NASA Technical Reports Server (NTRS)

    Rossman, Grant A.; Stackpoole, Mairead; Feldman, Jay; Venkatapathy, Ethiraj; Braun, Robert D.

    2013-01-01

    NASA Ames Research Center is developing Woven Thermal Protection System (WTPS) materials as a new class of heatshields for entry vehicles (Stackpoole). Currently, there are few options for ablative entry heatshield materials, none of which is ideally suited to the planetary probe missions currently of interest to NASA. While carbon phenolic was successfully used for the missions Pioneer Venus and Galileo (to Jupiter), the heritage constituents are no longer available. An alternate carbon phenolic would need to be qualified for probe missions, which is most efficient at heat fluxes greater than those currently of interest. Additional TPS materials such as Avcoat and PICA are not sufficiently robust for the heat fluxes required. As a result, there is a large TPS gap between the materials efficient at very high conditions (carbon phenolic) and those that are effective at low-moderate conditions (all others). Development of 3D Woven TPS is intended to fill this gap, targeting mid-density weaves that could with withstand mid-range heat fluxes between 1100 W/sq cm and 8000 W/sq cm (Venkatapathy (2012). Preliminary experimental studies have been performed to show the feasibility of WTPS as a future mid-range TPS material. One study performed in the mARC Jet Facility at NASA Ames Research Center characterized the performance of a 3D Woven TPS sample and compared it to 2D carbon phenolic samples at ply angles of 0deg, 23.5deg, and 90deg. Each sample contained similar compositions of phenolic and carbon fiber volume fractions for experimental consistency. The goal of this study was to compare the performance of the TPS materials by evaluating resulting recession and failure modes. After exposing both samples to similar heat flux and pressure conditions, the 2D carbon phenolic laminate was shown to experience significant delamination between layers and further pocketing underneath separated layers. The 3D Woven TPS sample did not experience the delamination or pocketing

  9. Eliminating friction with friction: 2D Janssen effect in a friction-driven system.

    PubMed

    Karim, M Yasinul; Corwin, Eric I

    2014-05-01

    The Janssen effect is a unique property of confined granular materials experiencing gravitational compaction in which the pressure at the bottom saturates with an increasing filling height due to frictional interactions with side walls. In this Letter, we replace gravitational compaction with frictional compaction. We study friction-compacted 2D granular materials confined within fixed boundaries on a horizontal conveyor belt. We find that even with high-friction side walls the Janssen effect completely vanishes. Our results demonstrate that gravity-compacted granular systems are inherently different from friction-compacted systems in at least one important way: vibrations induced by sliding friction with the driving surface relax away tangential forces on the walls. Remarkably, we find that the Janssen effect can be recovered by replacing the straight side walls with a sawtooth pattern. The mechanical force introduced by varying the sawtooth angle θ can be viewed as equivalent to a tunable friction force. By construction, this mechanical friction force cannot be relaxed away by vibrations in the system. PMID:24856724

  10. Eliminating Friction with Friction: 2D Janssen Effect in a Friction-Driven System

    NASA Astrophysics Data System (ADS)

    Karim, M. Yasinul; Corwin, Eric I.

    2014-05-01

    The Janssen effect is a unique property of confined granular materials experiencing gravitational compaction in which the pressure at the bottom saturates with an increasing filling height due to frictional interactions with side walls. In this Letter, we replace gravitational compaction with frictional compaction. We study friction-compacted 2D granular materials confined within fixed boundaries on a horizontal conveyor belt. We find that even with high-friction side walls the Janssen effect completely vanishes. Our results demonstrate that gravity-compacted granular systems are inherently different from friction-compacted systems in at least one important way: vibrations induced by sliding friction with the driving surface relax away tangential forces on the walls. Remarkably, we find that the Janssen effect can be recovered by replacing the straight side walls with a sawtooth pattern. The mechanical force introduced by varying the sawtooth angle θ can be viewed as equivalent to a tunable friction force. By construction, this mechanical friction force cannot be relaxed away by vibrations in the system.

  11. Comparison of 2D and 3D Computational Multiphase Fluid Flow Models of Oxygen Lancing of Pyrometallurgical Furnace Tap-Holes

    NASA Astrophysics Data System (ADS)

    Erwee, M. W.; Reynolds, Q. G.; Zietsman, J. H.

    2016-03-01

    Furnace tap-holes vary in design depending on the type of furnace and process involved, but they share one common trait: The tap-hole must be opened and closed periodically. In general, tap-holes are plugged with refractory clay after tapping, thereby stopping the flow of molten material. Once a furnace is ready to be tapped, drilling and/or lancing with oxygen are typically used to remove tap-hole clay from the tap-hole. Lancing with oxygen is an energy-intensive, mostly manual process, which affects the performance and longevity of the tap-hole refractory material as well as the processes inside the furnace. Computational modeling offers an opportunity to gain insight into the possible effects of oxygen lancing on various aspects of furnace operation.

  12. Comparison of 2D and 3D Computational Multiphase Fluid Flow Models of Oxygen Lancing of Pyrometallurgical Furnace Tap-Holes

    NASA Astrophysics Data System (ADS)

    Erwee, M. W.; Reynolds, Q. G.; Zietsman, J. H.

    2016-06-01

    Furnace tap-holes vary in design depending on the type of furnace and process involved, but they share one common trait: The tap-hole must be opened and closed periodically. In general, tap-holes are plugged with refractory clay after tapping, thereby stopping the flow of molten material. Once a furnace is ready to be tapped, drilling and/or lancing with oxygen are typically used to remove tap-hole clay from the tap-hole. Lancing with oxygen is an energy-intensive, mostly manual process, which affects the performance and longevity of the tap-hole refractory material as well as the processes inside the furnace. Computational modeling offers an opportunity to gain insight into the possible effects of oxygen lancing on various aspects of furnace operation.

  13. Digit ratio 2D:4D in relation to autism spectrum disorders, empathizing, and systemizing: a quantitative review.

    PubMed

    Hönekopp, Johannes

    2012-08-01

    Prenatal testosterone (PT) effects have been proposed to increase systemizing (the drive to understand lawful input-output relationships), to decrease empathizing (the drive to understand others), and to cause autism via hypermasculinization of the brain. Digit ratio 2D:4D is a putative marker of PT effects in humans. An online study (n = 1896) into the relationship between the Reading the Mind in the Eyes Test (a widely used measure of empathizing) and self-measured 2D:4D in a nonclinical sample is reported. No evidence for a link between empathizing and 2D:4D in either females or males emerged. Further, three meta-analyses are presented that look into the relationships of 2D:4D with autism spectrum disorder (ASD), systemizing, and empathizing. 2D:4D was substantially lower (more masculine) in ASD-affected individuals than in normal controls (d = -0.58, P < 0.001). However, 2D:4D was found to be virtually unrelated to systemizing and empathizing in normal adults. The results support the idea that high PT is a risk factor for autism, but they challenge the view that PT substantially contributes to sex differences in systemizing and empathizing. Possibly, this pattern reflects an interaction effect, whereby PT drives ASD characteristic changes only in brains with a specific damage. PMID:22674640

  14. A preliminary evaluation work on a 3D ultrasound imaging system for 2D array transducer

    NASA Astrophysics Data System (ADS)

    Zhong, Xiaoli; Li, Xu; Yang, Jiali; Li, Chunyu; Song, Junjie; Ding, Mingyue; Yuchi, Ming

    2016-04-01

    This paper presents a preliminary evaluation work on a pre-designed 3-D ultrasound imaging system. The system mainly consists of four parts, a 7.5MHz, 24×24 2-D array transducer, the transmit/receive circuit, power supply, data acquisition and real-time imaging module. The row-column addressing scheme is adopted for the transducer fabrication, which greatly reduces the number of active channels . The element area of the transducer is 4.6mm by 4.6mm. Four kinds of tests were carried out to evaluate the imaging performance, including the penetration depth range, axial and lateral resolution, positioning accuracy and 3-D imaging frame rate. Several strong reflection metal objects , fixed in a water tank, were selected for the purpose of imaging due to a low signal-to-noise ratio of the transducer. The distance between the transducer and the tested objects , the thickness of aluminum, and the seam width of the aluminum sheet were measured by a calibrated micrometer to evaluate the penetration depth, the axial and lateral resolution, respectively. The experiment al results showed that the imaging penetration depth range was from 1.0cm to 6.2cm, the axial and lateral resolution were 0.32mm and 1.37mm respectively, the imaging speed was up to 27 frames per second and the positioning accuracy was 9.2%.

  15. Exosomes and the MICA-NKG2D system in cancer.

    PubMed

    Clayton, Aled; Tabi, Zsuzsanna

    2005-01-01

    Exosomes are nanometer sized vesicles, secreted by a diverse range of cell types, whose biological functions remain ambiguous. Several groups have demonstrated the potential of manipulating exosomes for activating cellular immune responses. The possibility that exosomes may inhibit immunological responses, however, has not been widely addressed. We have investigated if exosomes produced by tumor cells can inhibit immunological functions, through modulating expression of the NKG2D receptor by effector cells. Incubating tumor exosomes with fresh peripheral blood leukocytes resulted in a marked reduction in the proportion of NKG2D-positive CD3+CD8+ Cells, and CD3- cells by 48 h. This effect was dose dependent and was shown with exosomes from different tumor cells including breast cancer and mesothelioma. Analysis of tumor exosome-phenotype revealed positive expression of several NKG2D ligands, and antibody blocking experiments revealed the importance of such ligands in driving the reduction in the proportion of NKG2D-positive effector cells. The functional importance of the decrease in NKG2D-positive cells was addressed in vitro cytotoxicity assays. For example a CD8+ T cell line pre-incubated with tumor exosomes had significant decreased capacity to kill peptide-pulsed T2 target cells. These data highlight a role for tumor exosomes bearing NKG2D ligands as a mechanism contributing to cancer immune evasion. PMID:15885603

  16. The development and testing of a 2D laboratory seismic modelling system for heterogeneous structure investigations

    NASA Astrophysics Data System (ADS)

    Mo, Yike; Greenhalgh, Stewart A.; Robertsson, Johan O. A.; Karaman, Hakki

    2015-05-01

    Lateral velocity variations and low velocity near-surface layers can produce strong scattered and guided waves which interfere with reflections and lead to severe imaging problems in seismic exploration. In order to investigate these specific problems by laboratory seismic modelling, a simple 2D ultrasonic model facility has been recently assembled within the Wave Propagation Lab at ETH Zurich. The simulated geological structures are constructed from 2 mm thick metal and plastic sheets, cut and bonded together. The experiments entail the use of a piezoelectric source driven by a pulse amplifier at ultrasonic frequencies to generate Lamb waves in the plate, which are detected by piezoelectric receivers and recorded digitally on a National Instruments recording system, under LabVIEW software control. The 2D models employed were constructed in-house in full recognition of the similitude relations. The first heterogeneous model features a flat uniform low velocity near-surface layer and deeper dipping and flat interfaces separating different materials. The second model is comparable but also incorporates two rectangular shaped inserts, one of low velocity, the other of high velocity. The third model is identical to the second other than it has an irregular low velocity surface layer of variable thickness. Reflection as well as transmission experiments (crosshole & vertical seismic profiling) were performed on each model. The two dominant Lamb waves recorded are the fundamental symmetric mode (non-dispersive) and the fundamental antisymmetric (flexural) dispersive mode, the latter normally being absent when the source transducer is located on a model edge but dominant when it is on the flat planar surface of the plate. Experimental group and phase velocity dispersion curves were determined and plotted for both modes in a uniform aluminium plate. For the reflection seismic data, various processing techniques were applied, as far as pre-stack Kirchhoff migration. The

  17. General solution of 2D and 3D superconducting quasiclassical systems: coalescing vortices and nanoisland geometries.

    PubMed

    Amundsen, Morten; Linder, Jacob

    2016-01-01

    An extension of quasiclassical Keldysh-Usadel theory to higher spatial dimensions than one is crucial in order to describe physical phenomena like charge/spin Hall effects and topological excitations like vortices and skyrmions, none of which are captured in one-dimensional models. We here present a numerical finite element method which solves the non-linearized 2D and 3D quasiclassical Usadel equation relevant for the diffusive regime. We show the application of this on three model systems with non-trivial geometries: (i) a bottlenecked Josephson junction with external flux, (ii) a nanodisk ferromagnet deposited on top of a superconductor and (iii) superconducting islands in contact with a ferromagnet. In case (i), we demonstrate that one may control externally not only the geometrical array in which superconducting vortices arrange themselves, but also to cause coalescence and tune the number of vortices. In case (iii), we show that the supercurrent path can be tailored by incorporating magnetic elements in planar Josephson junctions which also lead to a strong modulation of the density of states. The finite element method presented herein paves the way for gaining insight in physical phenomena which have remained largely unexplored due to the complexity of solving the full quasiclassical equations in higher dimensions. PMID:26961921

  18. Experimental investigation on the high chip rate of 2D incoherent optical CDMA system

    NASA Astrophysics Data System (ADS)

    Su, Guorui; Wang, Rong; Pu, Tao; Fang, Tao; Zheng, Jilin; Zhu, Huatao; Wu, Weijiang

    2015-08-01

    An innovative approach to realise high chip rate in OCDMA transmission system is proposed and experimentally investigation, the high chip rate is achieved through a 2-D wavelength-hopping time-spreading en/decoder based on the supercontinuum light source. The source used in the experiment is generated by high nonlinear optical fiber (HNLF), Erbium-doped fiber amplifier (EDFA) which output power is 26 dBm, and distributed feed-back laser diode which works in the gain switch state. The span and the flatness of the light source are 20 nm and 3 dB, respectively, after equalization of wavelength selective switch (WSS). The wavelength-hopping time-spreading coder can be changed 20 nm in the wavelength and 400 ps in the time, is consist of WSS and delay lines. Therefore, the experimental results show that the chip rate can achieve 500 Gchip/s, in the case of 2.5 Gbit/s, while keeping a bit error rate below forward error correction limit after 40 km transmission.

  19. General solution of 2D and 3D superconducting quasiclassical systems: coalescing vortices and nanoisland geometries

    PubMed Central

    Amundsen, Morten; Linder, Jacob

    2016-01-01

    An extension of quasiclassical Keldysh-Usadel theory to higher spatial dimensions than one is crucial in order to describe physical phenomena like charge/spin Hall effects and topological excitations like vortices and skyrmions, none of which are captured in one-dimensional models. We here present a numerical finite element method which solves the non-linearized 2D and 3D quasiclassical Usadel equation relevant for the diffusive regime. We show the application of this on three model systems with non-trivial geometries: (i) a bottlenecked Josephson junction with external flux, (ii) a nanodisk ferromagnet deposited on top of a superconductor and (iii) superconducting islands in contact with a ferromagnet. In case (i), we demonstrate that one may control externally not only the geometrical array in which superconducting vortices arrange themselves, but also to cause coalescence and tune the number of vortices. In case (iii), we show that the supercurrent path can be tailored by incorporating magnetic elements in planar Josephson junctions which also lead to a strong modulation of the density of states. The finite element method presented herein paves the way for gaining insight in physical phenomena which have remained largely unexplored due to the complexity of solving the full quasiclassical equations in higher dimensions. PMID:26961921

  20. Remapping of digital subtraction angiography on a standard fluoroscopy system using 2D-3D registration

    NASA Astrophysics Data System (ADS)

    Alhrishy, Mazen G.; Varnavas, Andreas; Guyot, Alexis; Carrell, Tom; King, Andrew; Penney, Graeme

    2015-03-01

    Fluoroscopy-guided endovascular interventions are being performing for more and more complex cases with longer screening times. However, X-ray is much better at visualizing interventional devices and dense structures compared to vasculature. To visualise vasculature, angiography screening is essential but requires the use of iodinated contrast medium (ICM) which is nephrotoxic. Acute kidney injury is the main life-threatening complication of ICM. Digital subtraction angiography (DSA) is also often a major contributor to overall patient radiation dose (81% reported). Furthermore, a DSA image is only valid for the current interventional view and not the new view once the C-arm is moved. In this paper, we propose the use of 2D-3D image registration between intraoperative images and the preoperative CT volume to facilitate DSA remapping using a standard fluoroscopy system. This allows repeated ICM-free DSA and has the potential to enable a reduction in ICM usage and radiation dose. Experiments were carried out using 9 clinical datasets. In total, 41 DSA images were remapped. For each dataset, the maximum and averaged remapping accuracy error were calculated and presented. Numerical results showed an overall averaged error of 2.50 mm, with 7 patients scoring averaged errors < 3 mm and 2 patients < 6 mm.

  1. MASSIVE BLACK HOLES IN STELLAR SYSTEMS: 'QUIESCENT' ACCRETION AND LUMINOSITY

    SciTech Connect

    Volonteri, M.; Campbell, D.; Mateo, M.; Dotti, M.

    2011-04-01

    Only a small fraction of local galaxies harbor an accreting black hole, classified as an active galactic nucleus. However, many stellar systems are plausibly expected to host black holes, from globular clusters to nuclear star clusters, to massive galaxies. The mere presence of stars in the vicinity of a black hole provides a source of fuel via mass loss of evolved stars. In this paper, we assess the expected luminosities of black holes embedded in stellar systems of different sizes and properties, spanning a large range of masses. We model the distribution of stars and derive the amount of gas available to a central black hole through a geometrical model. We estimate the luminosity of the black holes under simple, but physically grounded, assumptions on the accretion flow. Finally, we discuss the detectability of 'quiescent' black holes in the local universe.

  2. OJ287 binary black hole system.

    NASA Astrophysics Data System (ADS)

    Valtonen, M.; Ciprini, S.

    The light curve of the quasar OJ287 extends from 1891 up today without major gaps. This is partly due to extensive studies of historical plate archives by Rene Hudec and associates, partly due to several observing campaigns in recent times. Here we summarize the results of the 2005 - 2010 observing campaign in which several hundred scientists and amateur astronomers took part. The main results are the following: (1) The 2005 October optical outburst came at the expected time, thus confirming the general relativistic precession in the binary black hole system. This result disproved the model of a single black hole system with accretion disk oscillations, as well as several toy models of binaries without relativistic precession. In the latter models the main outburst would have been a year later. (2) The nature of the radiation of the 2005 October outburst was expected to be bremsstrahlung from hot gas at the temperature of 3× 105 oK. This was confirmed by combined ground based and ultraviolet observations using the XMM-Newton X-ray telescope. (3) A secondary outburst of the same nature was expected at 2007 September 13. Within the accuracy of observations (about 6 hours), it started at the correct time. Thus the prediction was accurate at the same level as the prediction of the return of Halley's comet in 1986. (4) Further synchrotron outbursts were expected following the two bremsstrahlung outbursts. They came as scheduled between 2007 October and 2009 December. (5) Due to the effect of the secondary on the overall direction of the jet, the parsec scale jet was expected to rotate in the sky by a large angle around 2009. This rotation may have been seen at high frequency radio observations. OJ287 binary black hole system is currently our best laboratory for testing theories of gravitation. Using OJ287, the correctness of General Relativity has now been demonstrated up to the third Post-Newtonian order, at higher order than has been possible using the binary pulsars.

  3. A three-dimensional measuring system based on 2D laser displacement sensor

    NASA Astrophysics Data System (ADS)

    Jiang, Sulun; Fu, Yuegang; Zhu, Wangbin; Zhang, Yingwei; Wang, Weichen

    2014-12-01

    3D(Three-dimensional) measurement has found its applications in the fields of automation process, Reverse engineering(RE), machine vision, as well as medical diagnostic. There are some disadvantages in the present 3D measurement methods. In this paper, a 2D laser displacement sensor-based and fast-dimensional surface measurement method for small size objects was proposed after analyzing the existing three-dimensional measurement methods. This method uses the information collected by 2D laser displacement sensor and encoder in pan-tilt to three-dimensional reconstruct 3D model. And then discuss the restrictive relation between angular velocity of pan-tilt and parameters (measurement range, signal sample rate, precision, etc.) of 2D laser displacement sensor. The sources of error and methods of improving precision were analyzed. Theoretical analyses and experiments have proved the feasibility, high-precision and practical of this method.

  4. Application of a Hybrid 3D-2D Laser Scanning System to the Characterization of Slate Slabs

    PubMed Central

    López, Marcos; Martínez, Javier; Matías, José María; Vilán, José Antonio; Taboada, Javier

    2010-01-01

    Dimensional control based on 3D laser scanning techniques is widely used in practice. We describe the application of a hybrid 3D-2D laser scanning system to the characterization of slate slabs with structural defects that are difficult for the human eye to characterize objectively. Our study is based on automating the process using a 3D laser scanner and a 2D camera. Our results demonstrate that the application of this hybrid system optimally characterizes slate slabs in terms of the defects described by the Spanish UNE-EN 12326-1 standard. PMID:22219696

  5. Determining ice water content from 2D crystal images in convective cloud systems

    NASA Astrophysics Data System (ADS)

    Leroy, Delphine; Coutris, Pierre; Fontaine, Emmanuel; Schwarzenboeck, Alfons; Strapp, J. Walter

    2016-04-01

    Cloud microphysical in-situ instrumentation measures bulk parameters like total water content (TWC) and/or derives particle size distributions (PSD) (utilizing optical spectrometers and optical array probes (OAP)). The goal of this work is to introduce a comprehensive methodology to compute TWC from OAP measurements, based on the dataset collected during recent HAIC (High Altitude Ice Crystals)/HIWC (High Ice Water Content) field campaigns. Indeed, the HAIC/HIWC field campaigns in Darwin (2014) and Cayenne (2015) provide a unique opportunity to explore the complex relationship between cloud particle mass and size in ice crystal environments. Numerous mesoscale convective systems (MCSs) were sampled with the French Falcon 20 research aircraft at different temperature levels from -10°C up to 50°C. The aircraft instrumentation included an IKP-2 (isokinetic probe) to get reliable measurements of TWC and the optical array probes 2D-S and PIP recording images over the entire ice crystal size range. Based on the known principle relating crystal mass and size with a power law (m=α•Dβ), Fontaine et al. (2014) performed extended 3D crystal simulations and thereby demonstrated that it is possible to estimate the value of the exponent β from OAP data, by analyzing the surface-size relationship for the 2D images as a function of time. Leroy et al. (2015) proposed an extended version of this method that produces estimates of β from the analysis of both the surface-size and perimeter-size relationships. Knowing the value of β, α then is deduced from the simultaneous IKP-2 TWC measurements for the entire HAIC/HIWC dataset. The statistical analysis of α and β values for the HAIC/HIWC dataset firstly shows that α is closely linked to β and that this link changes with temperature. From these trends, a generalized parameterization for α is proposed. Finally, the comparison with the initial IKP-2 measurements demonstrates that the method is able to predict TWC values

  6. Closed-loop control of a 2-D mems micromirror with sidewall electrodes for a laser scanning microscope system

    NASA Astrophysics Data System (ADS)

    Chen, Hui; Chen, Albert; Jie Sun, Wei; Sun, Zhen Dong; Yeow, John TW

    2016-01-01

    This article presents the development and implementation of a robust nonlinear control scheme for a 2-D micromirror-based laser scanning microscope system. The presented control scheme, built around sliding mode control approach and augmented an adaptive algorithm, is proposed to improve the tracking accuracy in presence of cross-axis effect. The closed-loop controlled imaging system is developed through integrating a 2-D micromirror with sidewall electrodes (SW), a laser source, NI field-programmable gate array (FPGA) hardware, the optics, position sensing detector (PSD) and photo detector (PD). The experimental results demonstrated that the proposed scheme is able to achieve accurate tracking of a reference triangular signal. Compared with open-loop control, the scanning performance is significantly improved, and a better 2-D image is obtained using the micromirror with the proposed scheme.

  7. Black holes in binary stellar systems and galactic nuclei

    NASA Astrophysics Data System (ADS)

    Cherepashchuk, A. M.

    2014-04-01

    In the last 40 years, following pioneering papers by Ya B Zeldovich and E E Salpeter, in which a powerful energy release from nonspherical accretion of matter onto a black hole (BH) was predicted, many observational studies of black holes in the Universe have been carried out. To date, the masses of several dozen stellar-mass black holes (M_BH = (4{-}20) M_\\odot) in X-ray binary systems and of several hundred supermassive black holes (M_BH = (10^{6}{-}10^{10}) M_\\odot) in galactic nuclei have been measured. The estimated radii of these massive and compact objects do not exceed several gravitational radii. For about ten stellar-mass black holes and several dozen supermassive black holes, the values of the dimensionless angular momentum a_* have been estimated, which, in agreement with theoretical predictions, do not exceed the limiting value a_* = 0.998. A new field of astrophysics, so-called black hole demography, which studies the birth and growth of black holes and their evolutionary connection to other objects in the Universe, namely stars, galaxies, etc., is rapidly developing. In addition to supermassive black holes, massive stellar clusters are observed in galactic nuclei, and their evolution is distinct from that of supermassive black holes. The evolutionary relations between supermassive black holes in galactic centers and spheroidal stellar components (bulges) of galaxies, as well as dark-matter galactic haloes are brought out. The launch into Earth's orbit of the space radio interferometer RadioAstron opened up the real possibility of finally proving that numerous discovered massive and highly compact objects with properties very similar to those of black holes make up real black holes in the sense of Albert Einstein's General Relativity. Similar proofs of the existence of black holes in the Universe can be obtained by intercontinental radio interferometry at short wavelengths \\lambda \\lesssim 1 mm (the international program, Event Horizon Telescope).

  8. Micro-electromechanical Systems for Probing Novel Strain Physics and Innovative Strain Devices in 2D Materials

    NASA Astrophysics Data System (ADS)

    Christopher, Jason; Vutukuru, Mounika; Bishop, David; Swan, Anna; Goldberg, Bennett

    Straining 2D materials can dramatically change electrical, thermal and optical properties and can even cause unconventional behavior such as generating pseudo-magnetic fields. However attempts at probing these effects have been hindered by the difficulty involved with precisely straining these materials. Here we present micro-electromechanical systems (MEMS) as an ideal platform for straining 2D materials because they are readily compatible with existing electronics and their size makes them compatible with 2D materials. Additionally the MEMS platform does more than facilitate experimentation; by freeing us to think of strain as dynamical it makes a whole new class of devices practical for next generation technology. To demonstrate the power of this platform we have for the first time measured the strain response of the Raman and photoluminescence spectra of suspended MoS2, and measured the friction force between MoS2 and the MEMS structure. This talk will touch on the basics of designing MEMS structures for straining 2D materials, how to transfer 2D materials onto MEMS without break either, proof of concept experimental results, and next steps in developing the MEMS platform. This work is supported by NSF DMR Grant 1411008, and author J. Christopher thanks the NDSEG program for its support.

  9. Disappearance of 2D Magnetic Character in Quasi-1D System CoNb2O6 under Magnetic Field

    NASA Astrophysics Data System (ADS)

    Mitsuda, Setsuo; Kobayashi, Satoru; Katagiri, Kouji; Yoshizawa, Hideki; Ishikawa, Masayasu; Miyatani, Kazuo; Kohn, Kay

    1995-07-01

    We report neutron scattering as well as ac susceptibility studies on the formation of magnetic ordering in a quasi-1D ferromagnetic chain system CoNb2O6 in magnetic fields up to 600 Oe. At T=1.5 K, a noncollinear ferrimagnetic (FR) phase with up-up-down spin arrangement along the b axis is field-induced in the magnetic field above ˜300 Oe. Interestingly, the pronounced 2D magnetic character previously found in the noncollinear antiferromagnetic phase disappears in the FR phase. This is direct evidence that the 2D magnetic character is due to the cancellation of interchain exchange fields at an apex site of a 2D isosceles-triangular lattice where quasi-1D ferromagnetic chains lie.

  10. Simulated KWAJEX Convective Systems Using a 2D and 3D Cloud Resolving Model and Their Comparisons with Radar Observations

    NASA Technical Reports Server (NTRS)

    Shie, Chung-Lin; Tao, Wei-Kuo; Simpson, Joanne

    2003-01-01

    The 1999 Kwajalein Atoll field experiment (KWAJEX), one of several major TRMM (Tropical Rainfall Measuring Mission) field experiments, has successfully obtained a wealth of information and observation data on tropical convective systems over the western Central Pacific region. In this paper, clouds and convective systems that developed during three active periods (Aug 7-12, Aug 17-21, and Aug 29-Sep 13) around Kwajalein Atoll site are simulated using both 2D and 3D Goddard Cumulus Ensemble (GCE) models. Based on numerical results, the clouds and cloud systems are generally unorganized and short lived. These features are validated by radar observations that support the model results. Both the 2D and 3D simulated rainfall amounts and their stratiform contribution as well as the heat, water vapor, and moist static energy budgets are examined for the three convective episodes. Rainfall amounts are quantitatively similar between the two simulations, but the stratiform contribution is considerably larger in the 2D simulation. Regardless of dimension, fo all three cases, the large-scale forcing and net condensation are the two major physical processes that account for the evolution of the budgets with surface latent heat flux and net radiation solar and long-wave radiation)being secondary processes. Quantitative budget differences between 2D and 3D as well as between various episodes will be detailed.Morover, simulated radar signatures and Q1/Q2 fields from the three simulations are compared to each other and with radar and sounding observations.

  11. Critical thickness of 2D to 3D transition in GexSi1-x/Si(001) system

    NASA Astrophysics Data System (ADS)

    Lozovoy, K. A.; Kokhanenko, A. P.; Voitsekhovskii, A. V.

    2016-07-01

    In this paper, Stranski-Krastanov growth of GexSi1-x epitaxial layers on the Si(001) surface is considered. Experimental investigations show that the moment of transition from 2D to 3D growth and the critical thickness of 2D layer at which this transition occurs play a key role during the synthesis of such materials. Among the most important parameters determining the peculiarities of the growth process and characteristics of emerging island ensembles are growth temperature and surface conditions (for example, the presence of surfactants). But existing theoretical models are not able to predict the values of the critical thickness in the whole range of growth temperatures and compositions x of solution for these systems. For the calculations of the critical thickness of transition from 2D to 3D growth, in this paper, a theoretical model based on general nucleation theory is proposed. This model is specified by taking into account dependencies of elastic modulus, lattices mismatch, and surface energy of the side facet on the composition x. As a result, dependencies of the critical thickness of Stranski-Krastanov transition on composition x and temperature are obtained. This allows one to determine conditions of transition from 2D to 3D growth mode in these systems. The simulated results explain experimentally observed results on temperature dependencies of the critical thickness for different germanium contents.

  12. Extreme g-factor anisotropy of low mobility 2D hole gas in GaAs/In0.2Ga0.8As/GaAs quantum well

    NASA Astrophysics Data System (ADS)

    Soldatov, I. V.; Germanenko, A. V.; Kozlova, N.

    2014-03-01

    The Shubnikov-de Haas (SdH) oscillations in low-mobility two-dimensional (2D) hole gas in a single quantum well GaAs/In0.2Ga0.8As/GaAs in magnetic fields up to 50 T were investigated. Analyzing the behavior of those oscillations within the framework of highly anisotropic spin splitting of the Landau levels, we obtained the values of the out-of-plane and in-plane g-factor of |g⊥|=4.4±0.6 and |g∥|=0.4±0.1 respectively.

  13. The evolution of host mass and black hole mass in quasi-stellar objects from the 2dF QSO Redshift Survey

    NASA Astrophysics Data System (ADS)

    Fine, S.; Croom, S. M.; Miller, L.; Babic, A.; Moore, D.; Brewer, B.; Sharp, R. G.; Boyle, B. J.; Shanks, T.; Smith, R. J.; Outram, P. J.; Loaring, N. S.

    2006-12-01

    We investigate the relation between the mass of supermassive black holes (MBH) in quasi-stellar objects (QSOs) and the mass of the dark matter haloes hosting them (MDH). We measure the widths of broad emission lines (MgII λ2798, CIV λ1549) from QSO composite spectra as a function of redshift. These widths are then used to determine virial black hole mass estimates. We compare our virial black hole mass estimates to dark matter halo masses for QSO hosts derived by Croom et al. based on measurements of QSO clustering. This enables us to trace the MBH-MDH relation over the redshift range z = 0.5-2.5. We calculate the mean zero-point of the MBH-MDH relation to be MBH = 108.4+/-0.2Msolar for an MDH = 1012.5Msolar. These data are then compared with several models connecting MBH and MDH as well as recent hydrodynamical simulations of galaxy evolution. We note that the flux-limited nature of QSO samples can cause a Malmquist-type bias in the measured zero-point of the MBH-MDH relation. The magnitude of this bias depends on the scatter in the MBH-MDH relation, and we re-evaluate the zero-point assuming three published values for this scatter. We create a subsample of our data defined by a constant magnitude interval around L* and find (1 + z)3.3+/-1.3 evolution in MBH between z ~ 0.5 and 2.5 for typical, L* QSOs. We also determine the Eddington ratios (L/LEdd) for the same subsample and find no significant evolution: (1 + z)-0.4+/-1.1. Taken at face value, our data suggest that a decrease in active black hole mass since z ~ 2.5 is the driving force behind luminosity evolution of typical, L*, optically selected QSOs. However, we note that our data are also consistent with a picture in which reductions in both black hole mass and accretion rate contribute equally to luminosity evolution. In addition, we find that these evolution results are strongly affected by the virial black hole mass estimators used. Changes to the calibration of these have a significant effect on the

  14. Development of an open source laboratory information management system for 2-D gel electrophoresis-based proteomics workflow

    PubMed Central

    Morisawa, Hiraku; Hirota, Mikako; Toda, Tosifusa

    2006-01-01

    Background In the post-genome era, most research scientists working in the field of proteomics are confronted with difficulties in management of large volumes of data, which they are required to keep in formats suitable for subsequent data mining. Therefore, a well-developed open source laboratory information management system (LIMS) should be available for their proteomics research studies. Results We developed an open source LIMS appropriately customized for 2-D gel electrophoresis-based proteomics workflow. The main features of its design are compactness, flexibility and connectivity to public databases. It supports the handling of data imported from mass spectrometry software and 2-D gel image analysis software. The LIMS is equipped with the same input interface for 2-D gel information as a clickable map on public 2DPAGE databases. The LIMS allows researchers to follow their own experimental procedures by reviewing the illustrations of 2-D gel maps and well layouts on the digestion plates and MS sample plates. Conclusion Our new open source LIMS is now available as a basic model for proteome informatics, and is accessible for further improvement. We hope that many research scientists working in the field of proteomics will evaluate our LIMS and suggest ways in which it can be improved. PMID:17018156

  15. Enhanced job control language procedures for the SIMSYS2D two-dimensional water-quality simulation system

    USGS Publications Warehouse

    Karavitis, G.A.

    1984-01-01

    The SIMSYS2D two-dimensional water-quality simulation system is a large-scale digital modeling software system used to simulate flow and transport of solutes in freshwater and estuarine environments. Due to the size, processing requirements, and complexity of the system, there is a need to easily move the system and its associated files between computer sites when required. A series of job control language (JCL) procedures was written to allow transferability between IBM and IBM-compatible computers. (USGS)

  16. Magnetospheres of black hole systems in force-free plasma

    SciTech Connect

    Palenzuela, Carlos; Garrett, Travis; Lehner, Luis; Liebling, Steven L.

    2010-08-15

    The interaction of black holes with ambient magnetic fields is important for a variety of highly energetic astrophysical phenomena. We study this interaction within the force-free approximation in which a tenuous plasma is assumed to have zero inertia. Blandford and Znajek used this approach to demonstrate the conversion of some of the black hole's energy into electromagnetic Poynting flux in stationary and axisymmetric single black hole systems. We adopt this approach and extend it to examine asymmetric and, most importantly, dynamical systems by implementing the fully nonlinear field equations of general relativity coupled to Maxwell's equations. For single black holes, we study, in particular, the dependence of the Poynting flux and show that, even for misalignments between the black hole spin and the direction of the asymptotic magnetic field, a Poynting flux is generated with a luminosity dependent on such misalignment. For binary black hole systems, we show both in the head-on and orbiting cases that the moving black holes generate a Poynting flux.

  17. Can mixed star-plus-wormhole systems mimic black holes?

    NASA Astrophysics Data System (ADS)

    Dzhunushaliev, Vladimir; Folomeev, Vladimir; Kleihaus, Burkhard; Kunz, Jutta

    2016-08-01

    We consider mixed strongly gravitating configurations consisting of a wormhole threaded by two types of ordinary matter. For such systems, the possibility of obtaining static spherically symmetric solutions describing compact massive central objects enclosed by high-redshift surfaces (black-hole-like configurations) is studied. Using the standard thin accretion disk model, we exhibit potentially observable differences allowing to distinguish the mixed systems from ordinary black holes with the same masses.

  18. Ti3CrCu4: A possible 2-D ferromagnetic spin fluctuating system

    NASA Astrophysics Data System (ADS)

    Dhar, S. K.; Provino, A.; Manfrinetti, P.; Kulkarni, R.; Goyal, Neeraj; Paudyal, D.

    2016-05-01

    Ti3CrCu4 is a new ternary compound which crystallizes in the tetragonal Ti3Pd5 structure type. The Cr atoms form square nets in the a-b plane (a = 3.124 Å) which are separated by an unusually large distance c = 11.228 Å along the tetragonal axis, thus forming a -2-D Cr-sublattice. The paramagnetic susceptibility is characterized by a low effective moment, μeff = 1.1 μB, a low paramagnetic Curie temperature θP (below 7 K) and a temperature independent χ0 = 6.7 x 10-4 emu/mol. The magnetization at 1.8 K increases rapidly with field nearly saturating to 0.2 μB/f.u. The zero field heat capacity C/T shows an upturn below 7 K (˜190 mJ/mol K2 at ˜0.1K) which is suppressed in applied magnetic fields and interpreted as suggesting the presence of spin fluctuations. The resistivity at low temperatures shows non-Fermi liquid behavior. Overall, the experimental data thus reveal an unusual magnetic state in Ti3CrCu4, which likely has its origin in the layered nature of the Cr sub-lattice and ferromagnetic spin fluctuations. Density functional theoretical calculations reveal a sharp Cr density of states peak just above the Fermi level, indicating the propensity of Ti3CrCu4 to become magnetic.

  19. Development of electrokinetic remediation for caesium: A feasibility study of 2D electrode configuration system

    NASA Astrophysics Data System (ADS)

    Syah Putra, Rudy

    2016-02-01

    Agar matrix was artificially contaminated with caesium and subjected to rapid assessment of electrokinetic treatment on the basis of the 2D electrode configuration. The effect of caesium concentration on the process was investigated using different electrode configuration (i.e. rectangular, hexagonal and triangular). During treatment the in situ pH distribution, the current flow, and the potential distribution were monitored. At the end of the treatment, the caesium concentration distribution was measured. The results of these experiments showed that for caesium contamination, pH control is essential in order to create a suitable environment throughout the agar matrix to enable contaminant removal. It was found that the type of electrode configuration used to control the pH affected the rate of caesium accumulation. All of the electrode configurations tested was effective, but the highest caesium extraction was achieved when the hexagonal pattern was used to control the pH. After 72 h of treatment at 50 mA, the concentration of caesium decreased gradually from the second and first layer of agar matrix throughout the cell, suggesting that most of the caesium was concentrated on the cathode part.

  20. High-power slim-hole drilling system

    SciTech Connect

    Cohen, J.H.; Maurer, W.C.; Leitko, C.E.

    1995-12-31

    Economic conditions in the oil and gas industry have encouraged the use of new methods to reduce drilling costs. Slim-hole drilling, abandoned in the past, has found new life because it offers savings by reducing equipment size, tubular products, and environmental impact. A new high-power slim-hole drilling system has been developed that overcomes many of the problems that led to the abandonment of slim holes in the past. This new system is composed of a new high-power positive-displacement motor and new TSP bits developed to run at high horsepowers and produce high drilling rates, The new slim-hole system has the potential for reducing drilling costs by 40 to 60 percent.

  1. Novel low-cost 2D/3D switchable autostereoscopic system for notebook computers and other portable devices

    NASA Astrophysics Data System (ADS)

    Eichenlaub, Jesse B.

    1995-03-01

    Mounting a lenticular lens in front of a flat panel display is a well known, inexpensive, and easy way to create an autostereoscopic system. Such a lens produces half resolution 3D images because half the pixels on the LCD are seen by the left eye and half by the right eye. This may be acceptable for graphics, but it makes full resolution text, as displayed by common software, nearly unreadable. Very fine alignment tolerances normally preclude the possibility of removing and replacing the lens in order to switch between 2D and 3D applications. Lenticular lens based displays are therefore limited to use as dedicated 3D devices. DTI has devised a technique which removes this limitation, allowing switching between full resolution 2D and half resolution 3D imaging modes. A second element, in the form of a concave lenticular lens array whose shape is exactly the negative of the first lens, is mounted on a hinge so that it can be swung down over the first lens array. When so positioned the two lenses cancel optically, allowing the user to see full resolution 2D for text or numerical applications. The two lenses, having complementary shapes, naturally tend to nestle together and snap into perfect alignment when pressed together--thus obviating any need for user operated alignment mechanisms. This system represents an ideal solution for laptop and notebook computer applications. It was devised to meet the stringent requirements of a laptop computer manufacturer including very compact size, very low cost, little impact on existing manufacturing or assembly procedures, and compatibility with existing full resolution 2D text- oriented software as well as 3D graphics. Similar requirements apply to high and electronic calculators, several models of which now use LCDs for the display of graphics.

  2. A convergent 2D finite-difference scheme for the Dirac–Poisson system and the simulation of graphene

    SciTech Connect

    Brinkman, D.; Heitzinger, C.; Markowich, P.A.

    2014-01-15

    We present a convergent finite-difference scheme of second order in both space and time for the 2D electromagnetic Dirac equation. We apply this method in the self-consistent Dirac–Poisson system to the simulation of graphene. The model is justified for low energies, where the particles have wave vectors sufficiently close to the Dirac points. In particular, we demonstrate that our method can be used to calculate solutions of the Dirac–Poisson system where potentials act as beam splitters or Veselago lenses.

  3. Temperature and Pinning Effects on Driving a 2D Electron System on a Helium Film: A Numerical Study

    NASA Astrophysics Data System (ADS)

    Damasceno, Pablo F.; Dasilva, Cláudio José; Rino, José Pedro; Cândido, Ladir

    2010-07-01

    Using numerical simulations we investigated the dynamic response to an externally driven force of a classical two-dimensional (2D) electron system on a helium film at finite temperatures. A potential barrier located at the center of the system behaves as a pinning center that results in an insulator state below a threshold driving force. We have found that the current-voltage characteristic obeys the scaling relation I= f ξ , with ξ ranging from ˜(1.0-1.7) for different pinning strengths and temperatures. Our results may be used to understand the spread range of ξ in experiments with typical characteristic of plastic depinning.

  4. Learning control system design based on 2-D theory - An application to parallel link manipulator

    NASA Technical Reports Server (NTRS)

    Geng, Z.; Carroll, R. L.; Lee, J. D.; Haynes, L. H.

    1990-01-01

    An approach to iterative learning control system design based on two-dimensional system theory is presented. A two-dimensional model for the iterative learning control system which reveals the connections between learning control systems and two-dimensional system theory is established. A learning control algorithm is proposed, and the convergence of learning using this algorithm is guaranteed by two-dimensional stability. The learning algorithm is applied successfully to the trajectory tracking control problem for a parallel link robot manipulator. The excellent performance of this learning algorithm is demonstrated by the computer simulation results.

  5. DOE HIGH-POWER SLIM-HOLE DRILLING SYSTEM

    SciTech Connect

    Dr. William C. Maurer; John H. Cohen; J. Chris Hetmaniak; Curtis Leitko

    1999-09-01

    This project used a systems approach to improve slim-hole drilling performance. A high power mud motor, having a double-length power section, and hybrid PDC/TSP drill bit were developed to deliver maximum horsepower to the rock while providing a long life down hole. This high-power slim-hole drilling system drills much faster than conventional slim-hole motor and bit combinations and holds significant potential to reduce slim-hole drilling costs. The oil and gas industries have been faced with downward price pressures since the 1980s. These pressures are not expected to be relieved in the near future. To maintain profitability, companies have had to find ways to reduce the costs of producing oil and gas. Drilling is one of the more costly operations in the production process. One method to reduce costs of drilling is to use smaller more mobile equipment. Slim holes have been drilled in the past using this principle. These wells can save money not only from the use of smaller drilling equipment, but also from reduced tubular costs. Stepping down even one casing size results in significant savings. However, slim holes have not found wide spread use for three reasons. First, until recently, the price of oil has been high so there were no forces to move the industry in this direction. Second, small roller bits and motors were not very reliable and they drilled slowly, removing much of the economic benefit. The third and final reason was the misconception that large holes were needed everywhere to deliver the desired production. Several factors have changed that will encourage the use of slim holes. The industry now favors any method of reducing the costs of producing oil and gas. In addition, the industry now understands that large holes are not always needed. Gas, in particular, can have high production rates in smaller holes. New materials now make it possible to manufacture improved bits and motors that drill for long periods at high rates. All that remains is to

  6. LASA (Lidar Atmospheric Sounder and Altimeter) Earth Observing System. Volume 2D: Instrument Panel Report

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The Earth Observing System (Eos) will provide an ideal forum in which the stronly synergistic characteristics of the lidar systems can be used in concert with the characteristics of a number of other sensors to better understand the Earth as a system. Progress in the development of more efficient and long-lasting laser systems will insure their availability in the Eos time frame. The necessary remote-sensing techniques are being developed to convert the Lidar Atmospheric Sounder and Altimeter (LASA) observations into the proper scientific parameters. Each of these activities reinforces the promise that LASA and GLRS will be a reality in the Eos era.

  7. Note: Reliable and non-contact 6D motion tracking system based on 2D laser scanners for cargo transportation

    SciTech Connect

    Kim, Young-Keun; Kim, Kyung-Soo

    2014-10-15

    Maritime transportation demands an accurate measurement system to track the motion of oscillating container boxes in real time. However, it is a challenge to design a sensor system that can provide both reliable and non-contact methods of 6-DOF motion measurements of a remote object for outdoor applications. In the paper, a sensor system based on two 2D laser scanners is proposed for detecting the relative 6-DOF motion of a crane load in real time. Even without implementing a camera, the proposed system can detect the motion of a remote object using four laser beam points. Because it is a laser-based sensor, the system is expected to be highly robust to sea weather conditions.

  8. Note: Reliable and non-contact 6D motion tracking system based on 2D laser scanners for cargo transportation

    NASA Astrophysics Data System (ADS)

    Kim, Young-Keun; Kim, Kyung-Soo

    2014-10-01

    Maritime transportation demands an accurate measurement system to track the motion of oscillating container boxes in real time. However, it is a challenge to design a sensor system that can provide both reliable and non-contact methods of 6-DOF motion measurements of a remote object for outdoor applications. In the paper, a sensor system based on two 2D laser scanners is proposed for detecting the relative 6-DOF motion of a crane load in real time. Even without implementing a camera, the proposed system can detect the motion of a remote object using four laser beam points. Because it is a laser-based sensor, the system is expected to be highly robust to sea weather conditions.

  9. A candidate sub-parsec supermassive binary black hole system.

    PubMed

    Boroson, Todd A; Lauer, Tod R

    2009-03-01

    The role of mergers in producing galaxies, together with the finding that most large galaxies harbour black holes in their nuclei, implies that binary supermassive black hole systems should be common. Here we report that the quasar SDSS J153636.22+044127.0 is a plausible example of such a system. This quasar shows two broad-line emission systems, separated in velocity by 3,500 km s(-1). A third system of unresolved absorption lines has an intermediate velocity. These characteristics are unique among known quasars. We interpret this object as a binary system of two black holes, having masses of 10(7.3) and 10(8.9) solar masses separated by approximately 0.1 parsec with an orbital period of approximately 100 years. PMID:19262667

  10. Twin robotic x-ray system for 2D radiographic and 3D cone-beam CT imaging

    NASA Astrophysics Data System (ADS)

    Fieselmann, Andreas; Steinbrener, Jan; Jerebko, Anna K.; Voigt, Johannes M.; Scholz, Rosemarie; Ritschl, Ludwig; Mertelmeier, Thomas

    2016-03-01

    In this work, we provide an initial characterization of a novel twin robotic X-ray system. This system is equipped with two motor-driven telescopic arms carrying X-ray tube and flat-panel detector, respectively. 2D radiographs and fluoroscopic image sequences can be obtained from different viewing angles. Projection data for 3D cone-beam CT reconstruction can be acquired during simultaneous movement of the arms along dedicated scanning trajectories. We provide an initial evaluation of the 3D image quality based on phantom scans and clinical images. Furthermore, initial evaluation of patient dose is conducted. The results show that the system delivers high image quality for a range of medical applications. In particular, high spatial resolution enables adequate visualization of bone structures. This system allows 3D X-ray scanning of patients in standing and weight-bearing position. It could enable new 2D/3D imaging workflows in musculoskeletal imaging and improve diagnosis of musculoskeletal disorders.

  11. Implementation of a system to life test 2-D laser arrays

    NASA Astrophysics Data System (ADS)

    Faltus, Thomas H.; Bicket, Daniel J.

    1992-02-01

    Multi-emitter laser devices, stacked to form 2-dimensional arrays, have been shown to effectively pump Nd:YAG slabs in solid state laser systems. Using these arrays as substitutes for flashlamps provides the potential for increased reliability of laser systems. However, to quantify this reliability improvement, laser arrays must be life tested. To ensure that the life test data accurately describes the array lifetimes, the life test system must possess the following characteristics: adequate control of operating stresses, to ensure that the test results apply to true use-conditions; continuous monitoring and recording of array health, to capture unpredictable variations in array performance; in-situ parameter measurement, to measure array performance without inducing handling damage; and extensive safety interlocks, to protect personnel from laser hazards. This paper describes an array life test system possessing these characteristics. It describes the system hardware, operating and test software, and the methodology behind the system's use. We demonstrate the system's performance by life testing 2-dimensional laser arrays having previously documented front facet anomalies. Disadvantages as well as advantages of design decisions are discussed.

  12. Note: Significant increase to the temporal resolution of 2D X-ray detectors using a novel beam chopper system

    SciTech Connect

    Küchemann, Stefan; Mahn, Carsten; Samwer, Konrad

    2014-01-15

    The investigation of short time dynamics using X-ray scattering techniques is commonly limited either by the read out frequency of the detector or by a low intensity. In this paper, we present a chopper system, which can increase the temporal resolution of 2D X-ray detectors by a factor of 13. This technique only applies to amorphous or polycrystalline samples due to their circular diffraction patterns. Using the chopper, we successfully increased the temporal resolution up to 5.1 ms during synchrotron experiments. For the construction, we provide a mathematical formalism, which, in principle, allows an even higher increase of the temporal resolution.

  13. Assessing HYDRUS-2D model to estimate soil water contents and olive tree transpiration fluxes under different water distribution systems

    NASA Astrophysics Data System (ADS)

    Autovino, Dario; Negm, Amro; Rallo, Giovanni; Provenzano, Giuseppe

    2016-04-01

    In Mediterranean countries characterized by limited water resources for agricultural and societal sectors, irrigation management plays a major role to improve water use efficiency at farm scale, mainly where irrigation systems are correctly designed to guarantee a suitable application efficiency and the uniform water distribution throughout the field. In the last two decades, physically-based agro-hydrological models have been developed to simulate mass and energy exchange processes in the soil-plant-atmosphere (SPA) system. Mechanistic models like HYDRUS 2D/3D (Šimunek et al., 2011) have been proposed to simulate all the components of water balance, including actual crop transpiration fluxes estimated according to a soil potential-dependent sink term. Even though the suitability of these models to simulate the temporal dynamics of soil and crop water status has been reported in the literature for different horticultural crops, a few researches have been considering arboreal crops where the higher gradients of root water uptake are the combination between the localized irrigation supply and the three dimensional root system distribution. The main objective of the paper was to assess the performance of HYDRUS-2D model to evaluate soil water contents and transpiration fluxes of an olive orchard irrigated with two different water distribution systems. Experiments were carried out in Castelvetrano (Sicily) during irrigation seasons 2011 and 2012, in a commercial farm specialized in the production of table olives (Olea europaea L., var. Nocellara del Belice), representing the typical variety of the surrounding area. During the first season, irrigation water was provided by a single lateral placed along the plant row with four emitters per plant (ordinary irrigation), whereas during the second season a grid of emitters laid on the soil was installed in order to irrigate the whole soil surface around the selected trees. The model performance was assessed based on the

  14. An automated calibration system that combines fringe projection and 2D digital image correlation

    NASA Astrophysics Data System (ADS)

    Siegmann, Philip; Felipe-Sesé, Luis A.; Díaz Garrido, Francisco; Piñeiro-Ave, José

    2015-09-01

    An optical non-contact and full-field system that allows large displacement measurements in x-, y- and z-direction is presented. The system combines 2-dimentional digital image correlation (for in-plane measurements) and fringe projection (for out-of-plane displacements) and uses only one camera. The in- and out-of-plane displacements are obtained at the same instant allowing real-time measurements thanks to a color encoding filtering procedure. The out-of-plane measurement allows the correction of the in-plane measurements and the system has to be precisely aligned by following an established alignment procedure. Furthermore, a calibration has to be done to obtain a fringe parameter k for each pixel of the specimen surface image necessary to relate the shifted phase with the out-of-plane displacements. The presented system obtains different values of k for each pixel because of the divergent and non-normal incidence of the fringe beam onto the sample surface (non zero incidence angle). The calibration is performed automatically and only has to be done once for each configuration of the system. The system is portable and can be easily adapted to measure large displacements and wide areas (using small incidence angle) or smaller distances but with higher resolutions (when increasing the incidence angle).

  15. A robust omnifont open-vocabulary Arabic OCR system using pseudo-2D-HMM

    NASA Astrophysics Data System (ADS)

    Rashwan, Abdullah M.; Rashwan, Mohsen A.; Abdel-Hameed, Ahmed; Abdou, Sherif; Khalil, A. H.

    2012-01-01

    Recognizing old documents is highly desirable since the demand for quickly searching millions of archived documents has recently increased. Using Hidden Markov Models (HMMs) has been proven to be a good solution to tackle the main problems of recognizing typewritten Arabic characters. These attempts however achieved a remarkable success for omnifont OCR under very favorable conditions, they didn't achieve the same performance in practical conditions, i.e. noisy documents. In this paper we present an omnifont, large-vocabulary Arabic OCR system using Pseudo Two Dimensional Hidden Markov Model (P2DHMM), which is a generalization of the HMM. P2DHMM offers a more efficient way to model the Arabic characters, such model offer both minimal dependency on the font size/style (omnifont), and high level of robustness against noise. The evaluation results of this system are very promising compared to a baseline HMM system and best OCRs available in the market (Sakhr and NovoDynamics). The recognition accuracy of the P2DHMM classifier is measured against the classic HMM classifier, the average word accuracy rates for P2DHMM and HMM classifiers are 79% and 66% respectively. The overall system accuracy is measured against Sakhr and NovoDynamics OCR systems, the average word accuracy rates for P2DHMM, NovoDynamics, and Sakhr are 74%, 71%, and 61% respectively.

  16. Single-snapshot 2D color measurement by plenoptic imaging system

    NASA Astrophysics Data System (ADS)

    Masuda, Kensuke; Yamanaka, Yuji; Maruyama, Go; Nagai, Sho; Hirai, Hideaki; Meng, Lingfei; Tosic, Ivana

    2014-03-01

    Plenoptic cameras enable capture of directional light ray information, thus allowing applications such as digital refocusing, depth estimation, or multiband imaging. One of the most common plenoptic camera architectures contains a microlens array at the conventional image plane and a sensor at the back focal plane of the microlens array. We leverage the multiband imaging (MBI) function of this camera and develop a single-snapshot, single-sensor high color fidelity camera. Our camera is based on a plenoptic system with XYZ filters inserted in the pupil plane of the main lens. To achieve high color measurement precision of this system, we perform an end-to-end optimization of the system model that includes light source information, object information, optical system information, plenoptic image processing and color estimation processing. Optimized system characteristics are exploited to build an XYZ plenoptic colorimetric camera prototype that achieves high color measurement precision. We describe an application of our colorimetric camera to color shading evaluation of display and show that it achieves color accuracy of ΔE<0.01.

  17. A neuromorphic VLSI device for implementing 2-D selective attention systems.

    PubMed

    Indiveri, G

    2001-01-01

    Selective attention is a mechanism used to sequentially select and process salient subregions of the input space, while suppressing inputs arriving from nonsalient regions. By processing small amounts of sensory information in a serial fashion, rather than attempting to process all the sensory data in parallel, this mechanism overcomes the problem of flooding limited processing capacity systems with sensory inputs. It is found in many biological systems and can be a useful engineering tool for developing artificial systems that need to process in real-time sensory data. In this paper we present a neuromorphic hardware model of a selective attention mechanism implemented on a very large scale integration (VLSI) chip, using analog circuits. The chip makes use of a spike-based representation for receiving input signals, transmitting output signals and for shifting the selection of the attended input stimulus over time. It can be interfaced to neuromorphic sensors and actuators, for implementing multichip selective attention systems. We describe the characteristics of the circuits used in the architecture and present experimental data measured from the system. PMID:18249973

  18. Hexatic and mesoscopic phases in a 2D quantum coulomb system.

    PubMed

    Clark, Bryan K; Casula, Michele; Ceperley, D M

    2009-07-31

    We study the Wigner crystal melting in a two-dimensional quantum system of distinguishable particles interacting via the 1/r Coulomb potential. We use quantum Monte Carlo methods to calculate its phase diagram, locate the Wigner crystal region, and analyze its instabilities towards the liquid phase. We discuss the role of quantum effects in the critical behavior of the system, and compare our numerical results with the classical theory of melting, and the microemulsion theory of frustrated Coulomb systems. We find a Pomeranchuk effect much larger then in solid helium. In addition, we find that the exponent for the algebraic decay of the hexatic phase differs significantly from the Kosterilitz-Thouless theory of melting. We search for the existence of mesoscopic phases and find evidence of metastable bubbles but no mesoscopic phase that is stable in equilibrium. PMID:19792514

  19. The evaluation of an inexpensive, 2D, video based gait assessment system for clinical use.

    PubMed

    Ugbolue, U Chris; Papi, Enrica; Kaliarntas, Konstantinos T; Kerr, Andrew; Earl, Leo; Pomeroy, Valerie M; Rowe, Philip J

    2013-07-01

    The purpose of this study was to investigate the clinical potential of an augmented-video-based-portable-system (AVPS). The AVPS included a walkway grid mat made of vinyl flooring, flat paper bull's eye markers, four photoswitches mounted on tripods, a light-indicator, a video camera, and a computer with ProTrainer System software. The AVPS output was compared to a "gold standard" 3D Vicon Motion Analysis System both statically and dynamically over a fixed range (-90° to +90°) using a two-segment-goniometric-rig marked with both bull's eye and retroreflective markers. At each segment angle position, three trials of data were captured. The reliability of the AVPS was also tested using three raters. Further twelve, young, healthy subjects participated in a concurrent validity study in which they performed six gait trials which were simultaneously recorded by both systems. Both motion analysis systems showed low levels of intra subject variability in all kinematic variables indicated by the size of the standard deviations across the six trials. There were no significant differences between the motion systems with respect to the kinematic variables (P>0.05). The results showed a high intra- and inter-rater reliability for both the kinematic and temporo-spatial parameters. With respect to gait events the lowest ICC value for the intra-rater reliability test was 0.993 for the kinematic variables, and ranged from 0.941 to 0.956 for the temporo-spatial variables and 0.731 to 0.954 for the tibia inclination angles. The validation data suggest the AVPS is capable of generating highly reliable and repeatable data when applied to normal subjects and could be used within the clinical setting. PMID:23465758

  20. A plastic scintillator-based 2D thermal neutron mapping system for use in BNCT studies.

    PubMed

    Ghal-Eh, N; Green, S

    2016-06-01

    In this study, a scintillator-based measurement instrument is proposed which is capable of measuring a two-dimensional map of thermal neutrons within a phantom based on the detection of 2.22MeV gamma rays generated via nth+H→D+γ reaction. The proposed instrument locates around a small rectangular water phantom (14cm×15cm×20cm) used in Birmingham BNCT facility. The whole system has been simulated using MCNPX 2.6. The results confirm that the thermal flux peaks somewhere between 2cm and 4cm distance from the system entrance which is in agreement with previous studies. PMID:26986813

  1. Topologically robust transport of entangled photons in a 2D photonic system.

    PubMed

    Mittal, Sunil; Orre, Venkata Vikram; Hafezi, Mohammad

    2016-07-11

    We theoretically study the transport of time-bin entangled photon pairs in a two-dimensional topological photonic system of coupled ring resonators. This system implements the integer quantum Hall model using a synthetic gauge field and exhibits topologically robust edge states. We show that the transport through edge states preserves temporal correlations of entangled photons whereas bulk transport does not preserve these correlations and can lead to significant unwanted temporal bunching or anti-bunching of photons. We study the effect of disorder on the quantum transport properties; while the edge transport remains robust, bulk transport is very susceptible, and in the limit of strong disorder, bulk states become localized. We show that this localization is manifested as an enhanced bunching/anti-bunching of photons. This topologically robust transport of correlations through edge states could enable robust on-chip quantum communication channels and delay lines for information encoded in temporal correlations of photons. PMID:27410836

  2. Tracer dispersion simulation in low wind speed conditions with a new 2D Langevin equation system

    NASA Astrophysics Data System (ADS)

    Anfossi, D.; Alessandrini, S.; Trini Castelli, S.; Ferrero, E.; Oettl, D.; Degrazia, G.

    The simulation of atmospheric dispersion in low wind speed conditions (LW) is still recognised as a challenge for modellers. Recently, a new system of two coupled Langevin equations that explicitly accounts for meandering has been proposed. It is based on the study of turbulence and dispersion properties in LW. The new system was implemented in the Lagrangian stochastic particle models LAMBDA and GRAL. In this paper we present simulations with this new approach applying it to the tracer experiments carried out in LW by Idaho National Engineering Laboratory (INEL, USA) in 1974 and by the Graz University of Technology and CNR-Torino near Graz in 2003. To assess the improvement obtained with the present model with respect to previous models not taking into account the meandering effect, the simulations for the INEL experiments were also performed with the old version of LAMBDA. The results of the comparisons clearly indicate that the new approach improves the simulation results.

  3. Interlayer tunneling studies of highly imbalanced bilayer 2D electron systems at νT= 1

    NASA Astrophysics Data System (ADS)

    Champagne, A. R.; Eisenstein, J. P.; Pfeiffer, L. N.; West, K. W.

    2007-03-01

    When the separation between two parallel 2-dimensional electron systems (2DES) becomes comparable to the average distance between electrons within a single layer, the system can support a quantum Hall state with total filling factor νT=1. This state can be described as a Bose condensate of excitons. Previous studies [1] have shown that close to the νT=1 phase boundary, a small imbalance in the number of electrons in each layer can strengthen the condensate. We report on interlayer tunneling measurements of the effect of large imbalances as a function of the interlayer spacing. We explore the possibility of competing order between the excitonic state and the (1/3, 2/3) fractional states in the individual layers. This work was supported by the NSF and the DOE. [1] I. B. Spielman, et al., Phys. Rev. B 70, 081303 (2004).

  4. Study of the height and density distributions of the 2-D granular system under vertical vibration

    NASA Astrophysics Data System (ADS)

    Pak, Hyuk Kyu; Kim, Kipom; Jun, Yonggun

    1998-03-01

    Melecular dynamic simulations and experiments are used to investigate the pattern formation of the granular materials in a vertically vibrated rigid container. The height and density distributions of the peak of the patterns in two dimensional system are measured using the simulation. The height distribution agrees with the experimental observation. At the peak of height of the pattern the density is observed minimum. From the information of the vertical velocities of the particles, the momentum flux distributions are studied also.

  5. A novel 2D wavelength-time chaos code in optical CDMA system

    NASA Astrophysics Data System (ADS)

    Zhang, Qi; Xin, Xiangjun; Wang, Yongjun; Zhang, Lijia; Yu, Chongxiu; Meng, Nan; Wang, Houtian

    2012-11-01

    Two-dimensional wavelength-time chaos code is proposed and constructed for a synchronous optical code division multiple access system. The access performance is compared between one-dimensional chaos code, WDM/chaos code and the proposed code. Comparison shows that two-dimensional wavelength-time chaos code possesses larger capacity, better spectral efficiency and bit-error ratio than WDM/chaos combinations and one-dimensional chaos code.

  6. Tracking contrast agents using real-time 2D photoacoustic imaging system for cardiac applications

    NASA Astrophysics Data System (ADS)

    Olafsson, Ragnar; Montilla, Leonardo; Ingram, Pier; Witte, Russell S.

    2009-02-01

    Photoacoustic (PA) imaging is a rapidly developing imaging modality that can detect optical contrast agents with high sensitivity. While detectors in PA imaging have traditionally been single element ultrasound transducers, use of array systems is desirable because they potentially provide high frame rates to capture dynamic events, such as injection and distribution of contrast in clinical applications. We present preliminary data consisting of 40 second sequences of coregistered pulse-echo (PE) and PA images acquired simultaneously in real time using a clinical ultrasonic machine. Using a 7 MHz linear array, the scanner allowed simultaneous acquisition of inphase-quadrature (IQ) data on 64 elements at a rate limited by the illumination source (Q-switched laser at 20 Hz) with spatial resolution determined to be 0.6 mm (axial) and 0.4 mm (lateral). PA images had a signal-to-noise ratio of approximately 35 dB without averaging. The sequences captured the injection and distribution of an infrared-absorbing contrast agent into a cadaver rat heart. From these data, a perfusion time constant of 0.23 s-1 was estimated. After further refinement, the system will be tested in live animals. Ultimately, an integrated system in the clinic could facilitate inexpensive molecular screening for coronary artery disease.

  7. Performance analysis of 2D asynchronous hard-limiting optical code-division multiple access system through atmospheric scattering channel

    NASA Astrophysics Data System (ADS)

    Zhao, Yaqin; Zhong, Xin; Wu, Di; Zhang, Ye; Ren, Guanghui; Wu, Zhilu

    2013-09-01

    Optical code-division multiple access (OCDMA) systems usually allocate orthogonal or quasi-orthogonal codes to the active users. When transmitting through atmospheric scattering channel, the coding pulses are broadened and the orthogonality of the codes is worsened. In truly asynchronous case, namely both the chips and the bits are asynchronous among each active user, the pulse broadening affects the system performance a lot. In this paper, we evaluate the performance of a 2D asynchronous hard-limiting wireless OCDMA system through atmospheric scattering channel. The probability density function of multiple access interference in truly asynchronous case is given. The bit error rate decreases as the ratio of the chip period to the root mean square delay spread increases and the channel limits the bit rate to different levels when the chip period varies.

  8. Application of Compressed Sensing to 2-D Ultrasonic Propagation Imaging System data

    SciTech Connect

    Mascarenas, David D.; Farrar, Charles R.; Chong, See Yenn; Lee, J.R.; Park, Gyu Hae; Flynn, Eric B.

    2012-06-29

    The Ultrasonic Propagation Imaging (UPI) System is a unique, non-contact, laser-based ultrasonic excitation and measurement system developed for structural health monitoring applications. The UPI system imparts laser-induced ultrasonic excitations at user-defined locations on a structure of interest. The response of these excitations is then measured by piezoelectric transducers. By using appropriate data reconstruction techniques, a time-evolving image of the response can be generated. A representative measurement of a plate might contain 800x800 spatial data measurement locations and each measurement location might be sampled at 500 instances in time. The result is a total of 640,000 measurement locations and 320,000,000 unique measurements. This is clearly a very large set of data to collect, store in memory and process. The value of these ultrasonic response images for structural health monitoring applications makes tackling these challenges worthwhile. Recently compressed sensing has presented itself as a candidate solution for directly collecting relevant information from sparse, high-dimensional measurements. The main idea behind compressed sensing is that by directly collecting a relatively small number of coefficients it is possible to reconstruct the original measurement. The coefficients are obtained from linear combinations of (what would have been the original direct) measurements. Often compressed sensing research is simulated by generating compressed coefficients from conventionally collected measurements. The simulation approach is necessary because the direct collection of compressed coefficients often requires compressed sensing analog front-ends that are currently not commercially available. The ability of the UPI system to make measurements at user-defined locations presents a unique capability on which compressed measurement techniques may be directly applied. The application of compressed sensing techniques on this data holds the potential to

  9. The optical system design and application of micro 2D barcode

    NASA Astrophysics Data System (ADS)

    Zhu, Yi-jia; Li, Liang-liang; Qian, Cheng; Liang, Zhong-cheng

    2010-11-01

    We show an optical system of micro visual tag which is based on the principle of microscope and the property of QR Code. Unlike current optical tag, such as barcodes, must be read within a short rang and occupy valuable physical space on products, the new tags can be shrunk to several millimeters and captured from a distance of over 0.5 meters. We design the transmitter according to the parameters of camera lens. We also take the detection range and apertures into account, meanwhile conduct simulations and experiments. The result shows that: the tag can be captured from a long distance, and the amplified image is able to accurately be decoded.

  10. Anomalous giant piezoresistance in AlAs 2D electron systems with antidot lattices.

    PubMed

    Gunawan, O; Gokmen, T; Shkolnikov, Y P; De Poortere, E P; Shayegan, M

    2008-01-25

    An AlAs two-dimensional electron system patterned with an antidot lattice exhibits a giant piezoresistance effect at low temperatures, with a sign opposite to the piezoresistance observed in the unpatterned region. We suggest that the origin of this anomalous giant piezoresistance is the nonuniform strain in the antidot lattice and the exclusion of electrons occupying the two conduction-band valleys from different regions of the sample. This is analogous to the well-known giant magnetoresistance effect, with valley playing the role of spin and strain the role of magnetic field. PMID:18233015

  11. Chaotically Spiking Canards in an Excitable System with 2D Inertial Fast Manifolds

    NASA Astrophysics Data System (ADS)

    Marino, Francesco; Marin, Francesco; Balle, Salvador; Piro, Oreste

    2007-02-01

    We introduce a new class of excitable systems with two-dimensional fast dynamics that includes inertia. A novel transition from excitability to relaxation oscillations is discovered where the usual Hopf bifurcation is followed by a cascade of period doubled and chaotic small excitable attractors and, as they grow, by a new type of canard explosion where a small chaotic background erratically but deterministically triggers excitable spikes. This scenario is also found in a model for a nonlinear Fabry-Perot cavity with one pendular mirror.

  12. Time dependent inflow-outflow boundary conditions for 2D acoustic systems

    NASA Technical Reports Server (NTRS)

    Watson, Willie R.; Myers, Michael K.

    1989-01-01

    An analysis of the number and form of the required inflow-outflow boundary conditions for the full two-dimensional time-dependent nonlinear acoustic system in subsonic mean flow is performed. The explicit predictor-corrector method of MacCormack (1969) is used. The methodology is tested on both uniform and sheared mean flows with plane and nonplanar sources. Results show that the acoustic system requires three physical boundary conditions on the inflow and one on the outflow boundary. The most natural choice for the inflow boundary conditions is judged to be a specification of the vorticity, the normal acoustic impedance, and a pressure gradient-density gradient relationship normal to the boundary. Specification of the acoustic pressure at the outflow boundary along with these inflow boundary conditions is found to give consistent reliable results. A set of boundary conditions developed earlier, which were intended to be nonreflecting is tested using the current method and is shown to yield unstable results for nonplanar acoustic waves.

  13. An active microwave imaging system for reconstruction of 2-D electrical property distributions.

    PubMed

    Meaney, P M; Paulsen, K D; Hartov, A; Crane, R K

    1995-10-01

    The goal of this work is to develop a microwave-based imaging system for hyperthermia treatment monitoring and assessment. Toward this end, a four transmit channel and four receive channel hardware device and concomitant image reconstruction algorithm have been realized. The hardware is designed to measure electric fields (i.e., amplitude and phase) at various locations in a phantom tank with and without the presence of various heterogeneities using standard heterodyning principles. Particular attention has been paid to designing a receiver with better than 115 dB of linear dynamic range which is necessary for imaging biological tissue which often has very high conductivity, especially for tissues with high water content. A calibration procedure has been developed to compensate for signal loss due to three-dimensional radiation in the measured data, since the reconstruction process is only two-dimensional at the present time. Results are shown which demonstrate the stability and accuracy of the measurement system, the extent to which the forward computational model agrees with the measured field distribution when the electrical properties are known, and image reconstructions of electrically unknown targets of varying diameter. In the latter case, images of both the reactive and resistive component of the electrical property distribution have been recoverable. Quantitative information on object location, size, and electrical properties results when the target is approximately one-half wavelength in size. Images of smaller objects lack the same level of quantitative information, but remain qualitatively correct. PMID:8582719

  14. Numerical and experimental studies of the elastic enhancement factor of 2D open systems

    NASA Astrophysics Data System (ADS)

    Sirko, Leszek; Białous, Małgorzata; Yunko, Vitalii; Bauch, Szymon; Ławniczak, Michał

    We present the results of numerical and experimental studies of the elastic enhancement factor W for microwave rough and rectangular cavities simulating two-dimensional chaotic and partially chaotic quantum billiards in the presence of moderate absorption strength. We show that for the frequency range ν = 15 . 0 - 18 . 5 GHz, in which the coupling between antennas and the system is strong enough, the values of W for the microwave rough cavity lie below the predictions of random matrix theory and on average they are above the theoretical results of V. Sokolov and O. Zhirov, Phys. Rev. E, 91, 052917 (2015). We also show that the enhancement factor W of a microwave rectangular cavity coupled to the external channels via microwave antennas, simulating a partially chaotic quantum billiard, calculated by applying the Potter-Rosenzweig model with κ = 2 . 8 +/- 0 . 5 is close to the experimental one. Our numerical and experimental results suggest that the enhancement factor can be used as a measure of internal chaos which can be especially useful for systems with significant openness or absorption. This work was partially supported by the Ministry of Science and Higher Education Grants N N202 130239 and UMO-2013/09/D/ST2/03727.

  15. Application of the digital watermarking technique in 2D barcode certificate anti-counterfeit systems

    NASA Astrophysics Data System (ADS)

    Chen, MuSheng; Lin, ShunDa

    2011-06-01

    At present, two dimensional barcode has been used in many fields. The safety of information in barcode is important, so this article brings up an effective two dimensional barcode encryption technology to assure it. Either two-dimensional barcode or digital watermarking technique is one of the most important parts and research focuses in anti-counterfeit fields. This paper designs and realizes a whole set of certificate administration system based on QRcode. On this platform the digital watermarking technique based on the spatial domain is used to encrypt the two dimensional barcode. The combination of two dimensional barcode and digital watermarking can improve the security and secrecy of personal information, and realize real anti-counterfeit certificates.

  16. Location detection and tracking of moving targets by a 2D IR-UWB radar system.

    PubMed

    Nguyen, Van-Han; Pyun, Jae-Young

    2015-01-01

    In indoor environments, the Global Positioning System (GPS) and long-range tracking radar systems are not optimal, because of signal propagation limitations in the indoor environment. In recent years, the use of ultra-wide band (UWB) technology has become a possible solution for object detection, localization and tracking in indoor environments, because of its high range resolution, compact size and low cost. This paper presents improved target detection and tracking techniques for moving objects with impulse-radio UWB (IR-UWB) radar in a short-range indoor area. This is achieved through signal-processing steps, such as clutter reduction, target detection, target localization and tracking. In this paper, we introduce a new combination consisting of our proposed signal-processing procedures. In the clutter-reduction step, a filtering method that uses a Kalman filter (KF) is proposed. Then, in the target detection step, a modification of the conventional CLEAN algorithm which is used to estimate the impulse response from observation region is applied for the advanced elimination of false alarms. Then, the output is fed into the target localization and tracking step, in which the target location and trajectory are determined and tracked by using unscented KF in two-dimensional coordinates. In each step, the proposed methods are compared to conventional methods to demonstrate the differences in performance. The experiments are carried out using actual IR-UWB radar under different scenarios. The results verify that the proposed methods can improve the probability and efficiency of target detection and tracking. PMID:25808773

  17. Matrix Cracking in Four Different 2D SiC/SiC Composite Systems

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.

    2003-01-01

    Silicon carbide fiber reinforced, silicon carbide matrix composites are some of the most advanced composite systems for high-temperature, high-stress applications in oxidizing environments. A basic area that needs to be understood for the purpose of material behavior modeling and optimization is the architectural, constituent, and mechanistic factors that contribute to non-linear stress-strain behavior. The mechanism that causes non-linear stress-strain in dense-matrix composites is the formation and propagation of bridged matrix cracks. In addition, the occurrence and propagation of matrix cracks controls the time-dependent strength-properties of these materials in oxidizing environments at elevated temperatures. A modal acoustic emission technique has been used to monitor and estimate the stress-dependent matrix cracking. Two different SiC matrix systems, chemical vapor infiltrated (CVI) and melt-infiltrated (MI), with two different SiC fiber reinforcement, Hi-Nicalon (trademark) and Sylramic (trademark) were compared. Even though the averages of the range where matrix cracking occurred for the composites varied by more than 0.1% in strain and almost 200 MPa in stress, the range or distribution for matrix cracking could be reduced to a narrow band of stress for CVI SiC and MI SiC composites if it were assumed that all matrix cracks emanate outside of the load-bearing fiber, interphase, CVI preform minicomposite. A simple relationship was determined to describe stress-dependent matrix cracking which can then be used to estimate the onset of large, bridged matrix cracks or for material behavior models.

  18. Location Detection and Tracking of Moving Targets by a 2D IR-UWB Radar System

    PubMed Central

    Nguyen, Van-Han; Pyun, Jae-Young

    2015-01-01

    In indoor environments, the Global Positioning System (GPS) and long-range tracking radar systems are not optimal, because of signal propagation limitations in the indoor environment. In recent years, the use of ultra-wide band (UWB) technology has become a possible solution for object detection, localization and tracking in indoor environments, because of its high range resolution, compact size and low cost. This paper presents improved target detection and tracking techniques for moving objects with impulse-radio UWB (IR-UWB) radar in a short-range indoor area. This is achieved through signal-processing steps, such as clutter reduction, target detection, target localization and tracking. In this paper, we introduce a new combination consisting of our proposed signal-processing procedures. In the clutter-reduction step, a filtering method that uses a Kalman filter (KF) is proposed. Then, in the target detection step, a modification of the conventional CLEAN algorithm which is used to estimate the impulse response from observation region is applied for the advanced elimination of false alarms. Then, the output is fed into the target localization and tracking step, in which the target location and trajectory are determined and tracked by using unscented KF in two-dimensional coordinates. In each step, the proposed methods are compared to conventional methods to demonstrate the differences in performance. The experiments are carried out using actual IR-UWB radar under different scenarios. The results verify that the proposed methods can improve the probability and efficiency of target detection and tracking. PMID:25808773

  19. Association of autonomic nervous system and EEG scalp potential during playing 2D Grand Turismo 5.

    PubMed

    Subhani, Ahmad Rauf; Likun, Xia; Saeed Malik, Aamir

    2012-01-01

    Cerebral activation and autonomic nervous system have importance in studies such as mental stress. The aim of this study is to analyze variations in EEG scalp potential which may influence autonomic activation of heart while playing video games. Ten healthy participants were recruited in this study. Electroencephalogram (EEG) and electrocardiogram (ECG) signals were measured simultaneously during playing video game and rest conditions. Sympathetic and parasympathetic innervations of heart were evaluated from heart rate variability (HRV), derived from the ECG. Scalp potential was measured by the EEG. The results showed a significant upsurge in the value theta Fz/alpha Pz (p<0.001) while playing game. The results also showed tachycardia while playing video game as compared to rest condition (p<0.005). Normalized low frequency power and ratio of low frequency/high frequency power were significantly increased while playing video game and normalized high frequency power sank during video games. Results showed synchronized activity of cerebellum and sympathetic and parasympathetic innervation of heart. PMID:23366661

  20. 2D position guidance with single-station optical scan-based system

    NASA Astrophysics Data System (ADS)

    Guo, Siyang; Ren, Yongjie; Huang, Zhe; Chen, Yang; Hong, Tianqi

    2015-08-01

    The workshop Measuring Position System (wMPS) based on intersection of optical planes is widely applied in large-scale metrology. However, in guidance areas concerning more about horizontal directions such as in the area of transporting with AGVs, the coordinate of z axis which represents the height of the vehicle is of no particular importance. Also, the installation and parameters calibration of wMPS is complex and time-consuming. In this paper, a new method with single transmitter measuring two dimensional coordinate to guide the moving object (except the vertical direction) is proposed and demonstrated. The three dimensional coordinate of receiver was calculated if its horizontal angle, vertical angle and the coordinate of vertical direction are given. In order to get the receiver's horizontal and vertical angle, a serious of mathematical formulas was derived from a model of single transmitter with two rotating laser planes. The coordinate of vertical direction was obtained by the laser tracker and mapped from laser tracker coordinates to transmitter coordinates. Concerning that the coordinate of the vertical direction remains almost the same if the object moves in the level ground, a series of vertical-direction coordinates of moving object was measured beforehand and the average value of coordinates was the approximate vertical-direction coordinates of every point. To verify this method, the points acquired by the transmitter were remeasured by the laser tracker. Finally, the coordinates were compared and the results were analyzed. The experiment results show that the method's measuring accuracy has reached 5mm.

  1. A novel beat-noise-reducing en/decoding technology for a coherent 2-D OCDMA system.

    PubMed

    Zheng, Jilin; Wang, Rong; Pu, Tao; Lu, Lin; Fang, Tao; Cheng, Yun; Chen, Xiangfei

    2009-10-12

    A novel fiber Bragg grating (FBG)-based en/decoder for a coherent two-dimensional (2-D) wavelength-time (WT) optical code-division multiple-access (OCDMA) system is proposed to suppress the beat noise (BN). The feasibility of en/decoding function and the effectiveness of BN suppression are demonstrated by the simulation comparison between the conventional and proposed scheme, which are also further validated by en/decoding experiments with two users at a data rate of 2.5, 5 and 10 Gb/s respectively. The further numerical performance analysis of the proposed en/decoding method reveals the BER improvement compared with the conventional system. PMID:20372663

  2. Software defined down-hole telemetric systems: training course

    NASA Astrophysics Data System (ADS)

    Morozov, Oleg G.; Danilaev, Dmitry P.; Denisenko, Pavel E.; Dautova, Rezeda V.; Nureev, Ilnur I.; Sakhabutdinov, Airat Z.; Feofilaktov, Sergey V.

    2015-03-01

    The paper is devoted for presentation of training course for applications and construction principles of poly-harmonic (two-frequency or four-frequency) cw laser systems for characterization of different nonlinear scattering effects in fibers and reflection of devices based on fiber Bragg gratings (FBG) in down-hole telemetric sensor nets, which are widely used in down-hole telemetric systems. In particular, we'll speak about evaluation of Mandelstam-Brillouin gain contour, Raman scattering contours and FBG reflection spectra characterization. Investigation methods and approaches are based on the unity of resonant structures of generated fiber responses on exciting and probing radiation or external physical fields for all given effects. The main decision is based on poly-harmonic probing of formed resonance responses. Training course united idea is software defined approach for down-hole parameters characterization in spite of measuring conversion principles.

  3. Taking the Pulse of a Black Hole System

    NASA Astrophysics Data System (ADS)

    2011-01-01

    Using two NASA X-ray satellites, astronomers have discovered what drives the "heartbeats" seen in the light from an unusual black hole system. These results give new insight into the ways that black holes can regulate their intake and severely curtail their growth. This study examined GRS 1915+105 (GRS 1915 for short), a binary system in the Milky Way galaxy containing a black hole about 14 times more massive than the Sun that is feeding off material from a companion star. As this material falls towards the black hole, it forms a swirling disk that emits X-rays. The black hole in GRS 1915 has been estimated to rotate at the maximum possible rate, allowing material in the inner disk to orbit very close to the black hole, at a radius only 20% larger than the event horizon, where the material travels at 50% the speed of light. Using the Chandra X-ray Observatory and the Rossi X-ray Timing Explorer (RXTE), researchers monitored this black hole system over a period of eight hours. As they watched, GRS 1915 gave off a short, bright pulse of X-ray light approximately every 50 seconds, varying in brightness by a factor of about three. This type of rhythmic cycle closely resembles an electrocardiogram of a human heart -- though at a slower pace. "Trying to understand the physics of this 'heartbeat state' is a little like trying to understand how a person's heart beats by watching changes in the blood flow through their veins," said Joey Neilsen, a graduate student at Harvard University, who presented these results from his dissertation at the American Astronomical Society (AAS) meeting in Seattle, Wash. It was previously known that GRS 1915 can develop such heartbeats when its mass consumption rate is very high. After monitoring it with the special combination of Chandra and RXTE, Neilsen and his collaborators realized that they could use the pulses to figure out what controls how much material the black hole consumes. "With each beat, the black hole pumps an enormous

  4. Combining the switched-beam and beam-steering capabilities in a 2-D phased array antenna system

    NASA Astrophysics Data System (ADS)

    Tsai, Yi-Che; Chen, Yin-Bing; Hwang, Ruey-Bing

    2016-01-01

    This paper presents the development, fabrication, and measurement of a novel beam-forming system consisting of 16 subarray antennas, each containing four aperture-coupled patch antennas, and the application of this system in smart wireless communication systems. The beam patterns of each of the subarray antennas can be switched toward one of nine zones over a half space by adjusting the specific phase delay angles among the four antenna elements. Furthermore, when all subarrays are pointed at the same zone, slightly continuous beam steering in around 1° increments can be achieved by dynamically altering the progressive phase delay angle among the subarrays. Phase angle calibration was implemented by coupling each transmitter output and down converter into the in-phase/quadrature baseband to calculate the correction factor to the weight. In addition, to validate the proposed concepts and the fabricated 2-D phased array antenna system, this study measured the far-field radiation patterns of the aperture-coupled patch array integrated with feeding networks and a phase-calibration system to carefully verify its spatially switched-beam and beam-steering characteristics at a center frequency of 2.4 GHz which can cover the industrial, scientific, and medical band and some long-term evolution applications. In addition, measured results were compared with calculated results, and agreement between them was observed.

  5. A Software System for Filling Complex Holes in 3D Meshes by Flexible Interacting Particles

    NASA Astrophysics Data System (ADS)

    Yamazaki, Daisuke; Savchenko, Vladimir

    3D meshes generated by acquisition devices such as laser range scanners often contain holes due to occlusion, etc. In practice, these holes are extremely geometrically and topologically complex. We propose a heuristic hole filling technique using particle systems to fill complex holes with arbitrary topology in 3D meshes. Our approach includes the following steps: hole identification, base surface creation, particle distribution, triangulation, and mesh refinement. We demonstrate the functionality of the proposed surface retouching system on synthetic and real data.

  6. Vertical 2D Heterostructures

    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.

  7. RBFNN-based hole identification system in conducting plates.

    PubMed

    Simone, G; Morabito, F C

    2001-01-01

    A neural-based signal processing system that exploits radial basis function neural network (RBFNN) is proposed to solve the problem of detecting and locating circular holes in conducting plates by means of nondestructive eddy currents testing. The capabilities of basic multilayer perceptron and radial basis function (RBF) schemes are first investigated. Since the achieved performance revealed insufficient, a two-step procedure is then analyzed: in the first step, an RBFNN is used to estimate the distances between the hole's center and the eddy current magnetic sensors; a least square algorithm is then exploited in order to locate the hole starting from the previously estimated distances. The performance of the proposed system are tested on a database of simulated experiments based on the a priori knowledge of the corresponding boundary value direct problem solution, by taking advantage of the closed-form analytical expression of the solution in order to generate a wide range of possible sensor-hole configurations. Both noiseless and noisy measurements are taken into account for assessing the system robustness. The main result achieved is discussed. PMID:18249972

  8. On the dynamics of tilted black hole-torus systems

    NASA Astrophysics Data System (ADS)

    Mewes, Vassilios; Galeazzi, Filippo; Font, José A.; Montero, Pedro J.; Stergioulas, Nikolaos

    2016-09-01

    We present results from three-dimensional, numerical relativity simulations of a tilted black hole-thick accretion disc system. The simulations are analysed using tracer particles in the disc which are advected with the flow. Such tracers, which we employ in these new simulations for the first time, provide a powerful means to analyse in detail the complex dynamics of tilted black hole-torus systems. We show how its use helps to gain insight into the overall dynamics of the system, discussing the origin of the observed black hole precession and the development of a global non-axisymmetric m = 1 mode in the disc. Our three-dimensional simulations show the presence of quasi-periodic oscillations (QPOs) in the instantaneous accretion rate, with frequencies in a range compatible with those observed in low-mass X-ray binaries with either a black hole or a neutron star component. The frequency ratio of the dominant low-frequency peak and the first overtone is o1/f ˜ 1.9, a frequency ratio not attainable when modelling the QPOs as p-mode oscillations in axisymmetric tori.

  9. Taking the Pulse of a Black Hole System

    NASA Astrophysics Data System (ADS)

    2011-01-01

    Using two NASA X-ray satellites, astronomers have discovered what drives the "heartbeats" seen in the light from an unusual black hole system. These results give new insight into the ways that black holes can regulate their intake and severely curtail their growth. This study examined GRS 1915+105 (GRS 1915 for short), a binary system in the Milky Way galaxy containing a black hole about 14 times more massive than the Sun that is feeding off material from a companion star. As this material falls towards the black hole, it forms a swirling disk that emits X-rays. The black hole in GRS 1915 has been estimated to rotate at the maximum possible rate, allowing material in the inner disk to orbit very close to the black hole, at a radius only 20% larger than the event horizon, where the material travels at 50% the speed of light. Using the Chandra X-ray Observatory and the Rossi X-ray Timing Explorer (RXTE), researchers monitored this black hole system over a period of eight hours. As they watched, GRS 1915 gave off a short, bright pulse of X-ray light approximately every 50 seconds, varying in brightness by a factor of about three. This type of rhythmic cycle closely resembles an electrocardiogram of a human heart -- though at a slower pace. "Trying to understand the physics of this 'heartbeat state' is a little like trying to understand how a person's heart beats by watching changes in the blood flow through their veins," said Joey Neilsen, a graduate student at Harvard University, who presented these results from his dissertation at the American Astronomical Society (AAS) meeting in Seattle, Wash. It was previously known that GRS 1915 can develop such heartbeats when its mass consumption rate is very high. After monitoring it with the special combination of Chandra and RXTE, Neilsen and his collaborators realized that they could use the pulses to figure out what controls how much material the black hole consumes. "With each beat, the black hole pumps an enormous

  10. Design of Advanced Photocatalysis System by Adatom Decoration in 2D Nanosheets of Group-IV and III–V Binary Compounds

    PubMed Central

    Jin, Hao; Dai, Ying; Huang, Bai-Biao

    2016-01-01

    Searching for novel photocatalysts is one of the most important topic in photocatalytic fields. In the present work, we propose a feasible approach to improve the photocatalytic activities of 2D bilayers through surface decoration, i.e. hydrogenation, halogenation, and hydroxylation. Our investigations demonstrate that after surface modification, the optical adsorption expands into the visible region, while a built-in electric field is induced due to the interlayer coupling, which can promote the charge separation for photogenerated electron-hole pairs. Our results show that the indirect-direct band gap transition of SiC, SnC, BN and GaN can be realised through adatom decoration. Furthermore, the surface-modified 2D bilayers have suitable VBM and CBM alignments with the oxidation and reduction potentials for water splitting, suggesting powerful potentials in energy and environmental applications. PMID:26983908

  11. Design of Advanced Photocatalysis System by Adatom Decoration in 2D Nanosheets of Group-IV and III–V Binary Compounds

    NASA Astrophysics Data System (ADS)

    Jin, Hao; Dai, Ying; Huang, Bai-Biao

    2016-03-01

    Searching for novel photocatalysts is one of the most important topic in photocatalytic fields. In the present work, we propose a feasible approach to improve the photocatalytic activities of 2D bilayers through surface decoration, i.e. hydrogenation, halogenation, and hydroxylation. Our investigations demonstrate that after surface modification, the optical adsorption expands into the visible region, while a built-in electric field is induced due to the interlayer coupling, which can promote the charge separation for photogenerated electron-hole pairs. Our results show that the indirect-direct band gap transition of SiC, SnC, BN and GaN can be realised through adatom decoration. Furthermore, the surface-modified 2D bilayers have suitable VBM and CBM alignments with the oxidation and reduction potentials for water splitting, suggesting powerful potentials in energy and environmental applications.

  12. Magneto-transport characteristics of a 2D electron system driven to negative magneto-conductivity by microwave photoexcitation

    NASA Astrophysics Data System (ADS)

    Mani, Ramesh; Kriisa, A.

    2015-03-01

    Negative diagonal magneto-conductivity/resistivity is a spectacular- and thought provoking- property of driven, far-from-equilibrium, low dimensional electronic systems. The physical response of this exotic electronic state is not yet fully understood since it is rarely encountered in experiment. The microwave-radiation-induced zero-resistance state in the high mobility GaAs/AlGaAs 2D electron system is believed to be an example where negative magneto-conductivity/resistivity is responsible for the observed phenomena. Here, we examine the magneto-transport characteristics of this negative conductivity/resistivity state in the microwave photo-excited two-dimensional electron system (2DES) through a numerical solution of the associated boundary value problem. The results suggest, surprisingly, that a bare negative diagonal conductivity/resistivity state in the 2DES under photo-excitation should yield a positive diagonal resistance with a concomitant sign reversal in the Hall voltage. Transport measurements are supported by the DOE, Office of Basic Energy Sciences, Material Sciences and Engineering Division under DE-SC0001762. Additional support by the ARO under W911NF-07-01-015.

  13. GRID2D/3D: A computer program for generating grid systems in complex-shaped two- and three-dimensional spatial domains. Part 1: Theory and method

    NASA Technical Reports Server (NTRS)

    Shih, T. I.-P.; Bailey, R. T.; Nguyen, H. L.; Roelke, R. J.

    1990-01-01

    An efficient computer program, called GRID2D/3D was developed to generate single and composite grid systems within geometrically complex two- and three-dimensional (2- and 3-D) spatial domains that can deform with time. GRID2D/3D generates single grid systems by using algebraic grid generation methods based on transfinite interpolation in which the distribution of grid points within the spatial domain is controlled by stretching functions. All single grid systems generated by GRID2D/3D can have grid lines that are continuous and differentiable everywhere up to the second-order. Also, grid lines can intersect boundaries of the spatial domain orthogonally. GRID2D/3D generates composite grid systems by patching together two or more single grid systems. The patching can be discontinuous or continuous. For continuous composite grid systems, the grid lines are continuous and differentiable everywhere up to the second-order except at interfaces where different single grid systems meet. At interfaces where different single grid systems meet, the grid lines are only differentiable up to the first-order. For 2-D spatial domains, the boundary curves are described by using either cubic or tension spline interpolation. For 3-D spatial domains, the boundary surfaces are described by using either linear Coon's interpolation, bi-hyperbolic spline interpolation, or a new technique referred to as 3-D bi-directional Hermite interpolation. Since grid systems generated by algebraic methods can have grid lines that overlap one another, GRID2D/3D contains a graphics package for evaluating the grid systems generated. With the graphics package, the user can generate grid systems in an interactive manner with the grid generation part of GRID2D/3D. GRID2D/3D is written in FORTRAN 77 and can be run on any IBM PC, XT, or AT compatible computer. In order to use GRID2D/3D on workstations or mainframe computers, some minor modifications must be made in the graphics part of the program; no

  14. Weakly Pinned Wigner Solid-FQHE Liquid Phase Transition in the 2-Dimensional Hole System under Ultrahigh Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Zhang, Chi; Du, Rui-Rui; Shi, Junren; Xie, Xincheng; Manfra, Michael J.; Pfeiffer, Loren N.; West, Ken W.; Park, Ju-Hyun

    2014-03-01

    In the two dimensional systems, Wigner crystals (WC) solid and fractional quantum Hall effect (FQHE) liquid phase compete under low temperature and high magnetic fields. Here, we exhibit unusual experimental results in the new developed C-doped two-dimensional hole samples. Our derivative conductivity measurements elucidate the existence of reentrant insulating phase (RIP) around the Landau level filling factor v = 1/5 in the 2D hole system. Moreover, we report the unexpected feature in the quantum phase transition between the Wigner Solid and FQHE liquid state in the 2D hole system under ultrahigh magnetic fields. Consequently, a systematic phase diagram is obtained based on our analysis. To our surprise, the excited electric field plays an equivalent role as the temperature in our specimen. From the duality of the electric field and temperature, a characteristic length of 450 nm is derived in our Analysis, which is the mean free path of the carriers. Based on the relation between the pinning gap and electric field, we obtained a characteristic domain size of the Wigner crystal.

  15. Prospects for experimental research on black holes in binary systems

    NASA Technical Reports Server (NTRS)

    Long, K. S.

    1979-01-01

    Cygnus X-1, the single widely accepted example of a black hole in a binary system, is characterized by unusual X-ray properties. The X-ray spectrum of Cygnus X-1 is not cut off above 20 keV, as in most strong X-ray sources. Recent scintillation counter measurements reveal a power law spectrum extending from 40 to 200 keV with a photon spectral index of approximately 2.2. However, it is not clear that these and other X-ray properties of the system are related to the black-hole nature of Cygnus X-1. It is suggested that without a direct test to show that the mass of the compact object in other systems similar to Cygnus X-1 (Circinus X-1 and GX339-4) exceeds the limit of the neutron star mass, a better understanding of the accretion disk phenomenon must be achieved to demonstrate how the properties peculiar to these systems are related to the black hole nature of the compact object. Current accretion disk models are examined, including the alpha-accretion disk and two-temperature accretion disk models.

  16. Generalized gradient approximation to the angle- and system-averaged exchange hole

    NASA Astrophysics Data System (ADS)

    Ernzerhof, Matthias; Perdew, John P.

    1998-09-01

    A simple analytic model is proposed for the angle- and system-averaged exchange hole of a many-electron system. The model hole depends on the local density and density gradient. It recovers a nonoscillatory local-spin density (LSD) approximation to the exchange hole for a vanishing density gradient. The model hole reproduces the exchange energy density of the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) for exchange, and facilitates a detailed understanding of the PBE GGA. The hole model is applied to atoms and molecules, and a comparison is made to exact and LSD angle- and system-averaged exchange holes. We find that the GGA hole model significantly improves upon the LSD model. Furthermore, the GGA hole model accurately describes the change in the exchange hole upon the formation of single bonds, but is less accurate for the formation of multiple bonds, where it misses the appearance of a long-range tail.

  17. General Relativistic Radiative Transfer: Applications to Black-Hole Systems

    NASA Technical Reports Server (NTRS)

    Wu, Kinwah; Fuerst, Steven V.; Mizuno, Yosuke; Nishikawa, Ken-Ichi; Branduardi-Raymont, Graziella; Lee, Khee-Gan

    2007-01-01

    We present general relativistic radiation transfer formulations which include opacity effects due to absorption, emission and scattering explicitly. We consider a moment expansions for the transfer in the presence of scattering. The formulation is applied to calculation emissions from accretion and outflows in black-hole systems. Cases with thin accretion disks and accretion tori are considered. Effects, such as emission anisotropy, non-stationary flows and geometrical self-occultation are investigated. Polarisation transfer in curved space-time is discussed qualitatively.

  18. Quantum interference in an electron-hole graphene ring system

    SciTech Connect

    Smirnov, D.; Schmidt, H.; Haug, R. J.

    2013-12-04

    Quantum interference is observed in a graphene ring system via the Aharonov Bohm effect. As graphene is a gapless semiconductor, this geometry allows to study the unique situation of quantum interference between electrons and holes in addition to the unipolar quantum interference. The period and amplitude of the observed Aharonov-Bohm oscillations are independent of the sign of the applied gate voltage showing the equivalence between unipolar and dipolar interference.

  19. Increase of spin dephasing times in a 2D electron system with degree of initial spin polarization

    NASA Astrophysics Data System (ADS)

    Stich, D.; Korn, T.; Schulz, R.; Schuh, D.; Wegscheider, W.; Schüller, C.

    2008-03-01

    We report on time-resolved Faraday/Kerr rotation measurements on a high-mobility 2D electron system. A variable initial spin polarization is created in the sample by a circularly polarized pump pulse, and the spin polarization is tracked by measuring the Faraday/Kerr rotation of a time-delayed probe pulse. By varying the pump intensity, the initial spin polarization is changed from the low-polarization limit to a polarization degree of several percent. The observed spin dephasing time increases from less than 20 ps to more than 200 ps as the initial spin polarization is increased. To exclude sample heating effects, additional measurements with constant pump intensity and variable degree of circular polarization are performed. The results confirm the theoretical prediction by Weng and Wu [Phys. Rev. B 68 (2003) 075312] that the spin dephasing strongly depends on the initial spin polarization degree. The microscopic origin for this is the Hartree-Fock term in the Coulomb interaction, which acts as an effective out-of plane magnetic field.

  20. Histamine-functionalized copolymer micelles as a drug delivery system in 2D and 3D models of breast cancer

    PubMed Central

    Zhang, Yuning; Lundberg, Pontus; Diether, Maren; Porsch, Christian; Janson, Caroline; Lynd, Nathaniel A.; Ducani, Cosimo; Malkoch, Michael; Malmström, Eva; Hawker, Craig J.; Nyström, Andreas M.

    2015-01-01

    Histamine functionalized block copolymers based on poly(allyl glycidyl ether)-b-poly(ethylene oxide) (PAGE-b-PEO) were prepared with different ratios of histamine and octyl or benzyl groups using UV-initiated thiol-ene click chemistry. At neutral pH, the histamine units are uncharged and hydrophobic, while in acidic environments, such as in the endosome, lysosomes, or extracellular sites of tumours, the histamine groups are positively charged and hydrophilic. pH responsible polymer drug delivery systems is a promising route to site specific delivery of drugs and offers the potential to avoid side effects of systemic treatment. Our detailed in vitro experiments of the efficacy of drug delivery and the intracellular localization characteristics of this library of NPs in 2D and 3D cultures of breast cancer revealed that the 50% histamine-modified polymer loaded with DOX exhibited rapid accumulation in the nucleus of free DOX within 2 h. Confocal studies showed enhanced mitochondrial localization and lysosomal escape when compared to controls. From these combined studies, it was shown that by accurately tuning the structure of the initial block copolymers, the resulting self-assembled NPs can be designed to exploit histamine as an endosomal escape trigger and the octyl/benzyl units give rise to a hydrophobic core resulting in highly efficacious drug delivery systems (DDS) with control over intracellular localization. Optimization and rational control of the intracellular localization of both DDS and the parent drug can give nanomedicines a substantial increase in efficacy and should be explored in future studies. PMID:26257912

  1. Slim-hole system uses special rig, drill string

    SciTech Connect

    Dupuis, D.; Fanuel, P.

    1993-07-01

    This paper reviews the new Euroslim drilling system which allows deep penetration of small diameter exploration and production wells. The Euroslim approach is an optimized conventional rotary drilling technique that allows continuous coring of the zone of interest. The initial project set the requirements of power transmission and hydraulic optimization to drill 4 3/4 inch holes to 3,500 meters with a single drill pipe size. A second drill string has now been designed to reach 4,000 meters with hole sizes ranging from 3 inches to 3 11/32 inches. This paper reviews the specifications of the drill pipe, core barrels, drill rig, stabilizers, drill bits, and deviation tools. A cost benefit analysis is also provided comparing the slim-bore drilling to conventional drilling.

  2. Preliminary analysis of the Baranof Fan system, Gulf of Alaska, based on 2D seismic reflection and multibeam bathymetry data

    NASA Astrophysics Data System (ADS)

    LeVoir, M. A.; Gulick, S. P.; Reece, R.; Barth, G. A.; Childs, J. R.; Everson, E. D.; Hart, P. E.; Johnson, K. M.; Lester, W. R.; Sliter, R. W.

    2011-12-01

    The Baranof Fan is a large marine sedimentary system in the eastern Gulf of Alaska, straddling the border between the U.S. and Canada. The volume of the Fan is estimated to be > 200,000 km3. Little is known about the depositional timing, the tectonic and morphologic processes influencing its development, or the role of channel aggradation and avulsion in its progression. Both tectonic and climatic transitions likely influenced the formation and evolution of the Fan, with events including the onset of northern hemisphere glaciation, the Mid-Pleistocene transition, the transport of the Yakutat Terrane along the southeast Alaskan margin, and the uplift of the Coast Mountains. 2D seismic reflection and multibeam bathymetry data were collected in the Gulf of Alaska in June 2011 aboard the R/V Marcus G. Langseth as a part of the U.S. Extended Continental Shelf (ECS) program assessing potential opportunities under the United Nations Law of the Sea Convention. The purpose of the 2011 survey was to determine sediment thickness, velocity structure, stratigraphic architecture, and crustal structure on of the Gulf of Alaska seafloor in support of U.S. continental shelf maritime zone definition. The surveyed geologic features include the Surveyor and Baranof sedimentary systems, which control active sediment distribution in the Gulf of Alaska. Preliminary analysis of these data show four distinct buried channels throughout the mid to distal Baranof Fan, ranging in width from 5 - 9 km, which may have evolved into modern surface channels (ranging in width from 2 - 7 km) visible in both the seismic data and multibeam bathymetry. The location and trajectory of these buried channels, however, appears distinct from the modern Horizon and Mukluk Channels; the buried channels may have avulsed into the modern channel systems, or could possibly be older and now abandoned branches instrumental in building the westward part of the Fan. All of the imaged channels appear to be depositional

  3. MEST- there is a dark hole around solar system

    NASA Astrophysics Data System (ADS)

    Cao, Dayong

    2015-04-01

    According to Einstein's equation and a TaiJi model-a balance between the spacetime and massenergy, the paper supposes there is a dark hole around the solar system, and they build up a balance system. The dark hole is made up of dark matter-dark massenergy that is spacetime center, so it is difficult observed. The supposing of dark hole will try to explain below questions: 1. What is dark matter? 2. Why and how do dark matter around galaxies and star? 3. Are there have relationship between dark matter and ``Oort Cloud''? 4. Why are there Jovian planets and terrestrial planets? 5. Why do the Jovian planets of big mass is far away from sun? 6. Why do planets have elliptic orbits and the same direction of their revolution? 7. How did periodicity Mass Extinctions caused by seasonal impaction of dark hole or dark matter? 8. Why did the dark asteroid look like dark comet? Why is asteroid-1950 DA such low density and rock hull of 67P/Churyumov-Gerasimenko? 9. Did the dark matter made coal, oil and natural gas during the Mass Extinctions on our earth? 10. Could consciousness of life help lives to renew and evolve from the Mass Extinctions? http://meeting.aps.org/link/BAPS.2015.APR.T1.26 http://meeting.aps.org/link/BAPS.2015.MAR.Z23.14 http://meetings.aps.org/link/BAPS.2013.MAR.H1.267 http://meetings.aps.org/link/BAPS.2009.APR.E1.33 http://meetings.aps.org/link/BAPS.2010.APR.C1.37 http://meetings.aps.org/link/BAPS.2014.APR.L1.3 http://meetings.aps.org/link/BAPS.2014.APR.L1.2

  4. The Validity of a New Low-Dose Stereoradiography System to Perform 2D and 3D Knee Prosthetic Alignment Measurements

    PubMed Central

    Meijer, Marrigje F.; Velleman, Ton; Boerboom, Alexander L.; Bulstra, Sjoerd K.; Otten, Egbert; Stevens, Martin; Reininga, Inge H. F.

    2016-01-01

    Introduction The EOS stereoradiography system has shown to provide reliable varus/valgus (VV) measurements of the lower limb in 2D (VV2D) and 3D (VV3D) after total knee arthroplasty (TKA). Validity of these measurements has not been investigated yet, therefore the purpose of this study was to determine validity of EOS VV2D and VV3D. Methods EOS images were made of a lower limb phantom containing a knee prosthesis, while varying VV angle from 15° varus to 15° valgus and flexion angle from 0° to 20°, and changing rotation from 20° internal to 20° external rotation. Differences between the actual VV position of the lower limb phantom and its position as measured on EOS 2D and 3D images were investigated. Results Rotation, flexion or VV angle alone had no major impact on VV2D or VV3D. Combination of VV angle and rotation with full extension did not show major differences in VV2D measurements either. Combination of flexion and rotation with a neutral VV angle showed variation of up to 7.4° for VV2D; maximum variation for VV3D was only 1.5°. A combination of the three variables showed an even greater distortion of VV2D, while VV3D stayed relatively constant. Maximum measurement difference between preset VV angle and VV2D was 9.8°, while the difference with VV3D was only 1.9°. The largest differences between the preset VV angle and VV2D were found when installing the leg in extreme angles, for example 15° valgus, 20° flexion and 20° internal rotation. Conclusions After TKA, EOS VV3D were more valid than VV2D, indicating that 3D measurements compensate for malpositioning during acquisition. Caution is warranted when measuring VV angle on a conventional radiograph of a knee with a flexion contracture, varus or valgus angle and/or rotation of the knee joint during acquisition. PMID:26771177

  5. On the global well-posedness of 2-D inhomogeneous incompressible Navier-Stokes system with variable viscous coefficient

    NASA Astrophysics Data System (ADS)

    Abidi, Hammadi; Zhang, Ping

    2015-10-01

    Given solenoidal vector u0 ∈H ˙ - 2 δ ∩H1 (R2), ρ0 - 1 ∈L2 (R2), and ρ0 ∈L∞ ∩W ˙ 1, r (R2) with a positive lower bound for δ ∈ (0, 1/2) and 2 < r < 2/1 - 2 δ, we prove that 2-D incompressible inhomogeneous Navier-Stokes system (1.1) has a unique global solution provided that the viscous coefficient μ (ρ0) is close enough to 1 in the L∞ norm compared to the size of δ and the norms of the initial data. With smoother initial data, we can prove the propagation of regularities for such solutions. Furthermore, for 1 < p < 4, if (ρ0 - 1, u0) belongs to the critical Besov spaces B˙p, 1 2/p (R2) × ( B˙p, 1 - 1 +2/p ∩L2 (R2)) and the B˙p, 1 2/p (R2) norm of ρ0 - 1 is sufficiently small compared to the exponential of ‖u0‖L2 2 +‖u0 ‖ B˙p, 1 - 1 +2/p, we prove the global well-posedness of (1.1) in the scaling invariant spaces. Finally for initial data in the almost critical Besov spaces, we prove the global well-posedness of (1.1) under the assumption that the L∞ norm of ρ0 - 1 is sufficiently small.

  6. High-power slim-hole drilling system

    SciTech Connect

    Cohen, J.H.

    1995-07-01

    The objective of this project is to implement new high-power slim-hole motors and bits into field gas well drilling applications. Development of improved motors and bits is critical because rotating time constitutes the major cost of drilling gas wells. Conventional motors drill most formations 2 to 3 times faster than rotary continuous coring systems due to greater power transfer to the drill bit. New high-power motors and large-cutter TSP bits being developed by Maurer Engineering, Inc. (MEI) drill 2 to 3 times faster than conventional motors. These slim-hole high-power motors and bits, which are ready for field testing on this DOE project, should reduce drilling costs by 20 to 40 percent in many areas. The objective of Phase I is to design, manufacture and laboratory test improved high-power slim-hole motors and large-cutter TSP bits. This work will be done in preparation for Phase II field tests. The objective of Phase II will be to field test the high-power motors and bits in Amoco`s Catoosa shallow-test well near Tulsa, OK, and in deep gas wells. The goal will be to drill 2 to 3 times faster than conventional motors and to reduce the drilling costs by 20 to 40 percent over the intervals drilled.

  7. Masses of black holes in binary stellar systems

    NASA Astrophysics Data System (ADS)

    Cherepashchuk, Anatolii M.

    1996-08-01

    Mass determination methods and their results for ten black holes in X-ray binary systems are summarised. A unified interpretation of the radial velocity and optical light curves allows one to reliably justify the close binary system model and to prove the correctness of determination of the optical star mass function fv(m).The orbit plane inclination i can be estimated from an analysis of optical light curve of the system, which is due mainly to the ellipsoidal shape of the optical star (the so-called ellipticity effect). The component mass ratio q = mx/mv is obtained from information about the distance to the binary system as well as from data about rotational broadening of absorption lines in the spectrum of the optical star. These data allow one to obtain from the value of fv(m) a reliable value of the black hole mass mx or its low limit, as well as the optical star mass mv. An independent estimate of the optical star mass mv obtained from information about its spectral class and luminosity gives us test results. Additional test comes from information about the absence or presence of X-ray eclipses in the system. Effects of the non-zero dimension of the optical star, its pear-like shape, and X-ray heating on the absorption line profiles and the radial velocity curve are investigated. It is very significant that none of ten known massive (mx > 3M) X-ray sources considered as black hole candidates is an X-ray pulsar or an X-ray burster of the first kind.

  8. High-throughput critical dimensions uniformity (CDU) measurement of two-dimensional (2D) structures using scanning electron microscope (SEM) systems

    NASA Astrophysics Data System (ADS)

    Fullam, Jennifer; Boye, Carol; Standaert, Theodorus; Gaudiello, John; Tomlinson, Derek; Xiao, Hong; Fang, Wei; Zhang, Xu; Wang, Fei; Ma, Long; Zhao, Yan; Jau, Jack

    2011-03-01

    In this paper, we tested a novel methodology of measuring critical dimension (CD) uniformity, or CDU, with electron beam (e-beam) hotspot inspection and measurement systems developed by Hermes Microvision, Inc. (HMI). The systems were used to take images of two-dimensional (2D) array patterns and measure CDU values in a custom designated fashion. Because this methodology combined imaging of scanning micro scope (SEM) and CD value averaging over a large array pattern of optical CD, or OCD, it can measure CDU of 2D arrays with high accuracy, high repeatability and high throughput.

  9. Robust design of feedback feed-forward iterative learning control based on 2D system theory for linear uncertain systems

    NASA Astrophysics Data System (ADS)

    Li, Zhifu; Hu, Yueming; Li, Di

    2016-08-01

    For a class of linear discrete-time uncertain systems, a feedback feed-forward iterative learning control (ILC) scheme is proposed, which is comprised of an iterative learning controller and two current iteration feedback controllers. The iterative learning controller is used to improve the performance along the iteration direction and the feedback controllers are used to improve the performance along the time direction. First of all, the uncertain feedback feed-forward ILC system is presented by an uncertain two-dimensional Roesser model system. Then, two robust control schemes are proposed. One can ensure that the feedback feed-forward ILC system is bounded-input bounded-output stable along time direction, and the other can ensure that the feedback feed-forward ILC system is asymptotically stable along time direction. Both schemes can guarantee the system is robust monotonically convergent along the iteration direction. Third, the robust convergent sufficient conditions are given, which contains a linear matrix inequality (LMI). Moreover, the LMI can be used to determine the gain matrix of the feedback feed-forward iterative learning controller. Finally, the simulation results are presented to demonstrate the effectiveness of the proposed schemes.

  10. SATURATION MEASUREMENT OF IMMISCIBLE FLUIDS IN 2-D STATIC SYSTEMS: VALIDATION BY LIGHT TRANSMISSION VISUALIZATION (SAN FRANCISCO, CA)

    EPA Science Inventory

    This study is a part of an ongoing research project that aims at assessing the environmental benefits of DNAPL removal. The laboratory part of the research project is to examine the functional relationship between DNAPL architecture, mass removal and contaminant mass flux in 2-D ...

  11. Sensitivity and System Response of Pin Power Peaking in VVER-1000 Fuel Assembly Using TSUNAMI-2D

    NASA Astrophysics Data System (ADS)

    Frybort, J.

    2014-04-01

    Pin power peaking in a VVER-1000 fuel assembly and its sensitivity and uncertainty was analyzed by TSUNAMI-2D code. Several types of fuel assemblies were considered. They differ in number and position of gadolinium fuel pins. The calculations were repeated for several fuel compositions obtained by fuel depletion calculation. The results are quantified sensitivity data, which can be used for enrichment profiling.

  12. A New Blind 2D-RAKE Receiver Based on CMA Criteria for Spread Spectrum Systems Suitable for Software Defined Radio Architecture

    NASA Astrophysics Data System (ADS)

    Takayama, Kei; Kamiya, Yukihiro; Fujii, Takeo; Suzuki, Yasuo

    Spread Spectrum (SS) has been widely used for various wireless systems such as cellular systems, wireless local area network (LAN) and so on. Using multiple antennas at the receiver, two-dimensional (2D) RAKE is realized over the time- and the space-domain. However, it should be noted that the 2D-RAKE receiver must detect the bit timing prior to the RAKE combining. In case of deep fading, it is often difficult to detect it due to low signal-to-noise power ratio (SNR). To solve this problem, we propose a new blind 2D-RAKE receiver based on the constant modulus algorithm (CMA). Since it does not need a priori bit timing detection, it is possible to compensate frequency selective fading even in very low SNR environments. The proposed method is particularly suitable for the software defined radio (SDR) architecture. The performance of the proposed method is investigated through computer simulations.

  13. System for Image-Processing-Based Inspection of a Screw Hole on a Molded Plastic Frame

    NASA Astrophysics Data System (ADS)

    Satoh, Hironobu; Takeda, Fumiaki

    A screw hole is incorrectly molded if the pin on the mold is broken when the plastic is molded by injection molding. Sampling inspection is carried out manually to identify the incorrectly molded screw hole. In the sampling inspection, the incorrectly molded screw hole on the molded plastic frame is rarely overlooked. Therefore, the development of a system for the high-precision identification of the incorrectly molded screw hole is required. The purpose of this study is to develop a screw-hole inspection system that distinguishes between a correctly molded screw hole and an incorrectly molded one. In this paper, a screw-hole inspection system is proposed. There is a need to capture clearly the screw hole on an uneven plastic frame and therefore, a multi-camera system is used. The proposed system consists of several Web cameras with the individual adjustable focus. Moreover, the inspection of the screw holes is performed using an inspection algorithm that is developed for a multi-camera system. When 2548 correctly molded screw holes and 2940 incorrectly molded screw holes were inspected by the proposed system, the inspection success rate was 100.0%. Finally, we have verified its effectiveness by performing an experiment.

  14. Structural environments of carboxyl groups in natural organic molecules from terrestrial systems. Part 2: 2D NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Deshmukh, Ashish P.; Pacheco, Carlos; Hay, Michael B.; Myneni, Satish C. B.

    2007-07-01

    Carboxyl groups are abundant in natural organic molecules (NOM) and play a major role in their reactivity. The structural environments of carboxyl groups in IHSS soil and river humic samples were investigated using 2D NMR (heteronuclear and homonuclear correlation) spectroscopy. Based on the 1H- 13C heteronuclear multiple-bond correlation (HMBC) spectroscopy results, the carboxyl environments in NOM were categorized as Type I (unsubstituted and alkyl-substituted aliphatic/alicyclic), Type II (functionalized carbon substituted), Type IIIa, b (heteroatom and olefin substituted), and Type IVa, b (5-membered heterocyclic aromatic and 6-membered aromatic). The most intense signal in the HMBC spectra comes from the Type I carboxyl groups, including the 2JCH and 3JCH couplings of unsubstituted aliphatic and alicyclic acids, though this spectral region also includes the 3JCH couplings of Type II and III structures. Type II and III carboxyls have small but detectable 2JCH correlations in all NOM samples except for the Suwannee River humic acid. Signals from carboxyls bonded to 5-membered aromatic heterocyclic fragments (Type IVa) are observed in the soil HA and Suwannee River FA, while correlations to 6-membered aromatics (Type IVb) are only observed in Suwannee River HA. In general, aromatic carboxylic acids may be present at concentrations lower than previously imagined in these samples. Vibrational spectroscopy results for these NOM samples, described in an accompanying paper [Hay M. B. and Myneni S. C. B. (2007) Structural environments of carboxyl groups in natural organic molecules from terrestrial systems. Part 1: Infrared spectroscopy. Geochim. Cosmochim. Acta (in press)], suggest that Type II and Type III carboxylic acids with α substituents (e.g., -OH, -OR, or -CO 2H) constitute the majority of carboxyl structures in all humic substances examined. Furoic and salicylic acid structures (Type IV) are also feasible fragments, albeit as minor constituents. The

  15. Analysis of 2D THz-Raman spectroscopy using a non-Markovian Brownian oscillator model with nonlinear system-bath interactions.

    PubMed

    Ikeda, Tatsushi; Ito, Hironobu; Tanimura, Yoshitaka

    2015-06-01

    We explore and describe the roles of inter-molecular vibrations employing a Brownian oscillator (BO) model with linear-linear (LL) and square-linear (SL) system-bath interactions, which we use to analyze two-dimensional (2D) THz-Raman spectra obtained by means of molecular dynamics (MD) simulations. In addition to linear infrared absorption (1D IR), we calculated 2D Raman-THz-THz, THz-Raman-THz, and THz-THz-Raman signals for liquid formamide, water, and methanol using an equilibrium non-equilibrium hybrid MD simulation. The calculated 1D IR and 2D THz-Raman signals are compared with results obtained from the LL+SL BO model applied through use of hierarchal Fokker-Planck equations with non-perturbative and non-Markovian noise. We find that all of the qualitative features of the 2D profiles of the signals obtained from the MD simulations are reproduced with the LL+SL BO model, indicating that this model captures the essential features of the inter-molecular motion. We analyze the fitted 2D profiles in terms of anharmonicity, nonlinear polarizability, and dephasing time. The origins of the echo peaks of the librational motion and the elongated peaks parallel to the probe direction are elucidated using optical Liouville paths. PMID:26049441

  16. Spin-spin correlation functions of spin systems coupled to 2-d quantum gravity for 0 < c < 1.

    NASA Astrophysics Data System (ADS)

    Ambjørn, J.; Anagnostopoulos, K. N.; Magnea, U.; Thorleifsson, G.

    1997-02-01

    We perform Monte Carlo simulations of 2-d dynamically triangulated surfaces coupled to Ising and three-states Potts model matter. By measuring spin-spin correlation functions as a function of the geodesic distance we provide substantial evidence for a diverging correlation length at βc. The corresponding scaling exponents are directly related to the KPZ exponents of the matter fields as conjectured in [4].

  17. The application of 2-D dual nanoscale liquid chromatography and triple quadrupole-linear ion trap system for the identification of proteins.

    PubMed

    Tschäppät, Viviane; Varesio, Emmanuel; Signor, Luca; Hopfgartner, Gérard

    2005-09-01

    2-D nanoscale LC combined with a triple quadrupole-linear ion trap mass spectrometer was applied to the analysis of a complex peptide mixture. A 2-D dual nanoscale LC-MS/MS system was compared to a conventional one. Peptides were separated with a strong cation exchange (SCX) microcolumn in the first dimension and two C18 nanocolumns were used as second dimension. MS experiments were performed using information-dependent data acquisition, where two precursor ions were selected from an enhanced MS (EMS) or an enhanced multicharged ion (EMC) as survey scan. The major benefit of EMC instead of EMS was a two-fold reduction of the data file and a 15% increase of characterized proteins. The advantage of the 2-D dual nanoscale LC-MS/MS system versus the conventional 2-D nanoscale LC-MS/MS system was reflected in the significant increase of peptides which were successfully identified within the same time frame. The first factor contributing to this increase was that the mass spectrometer was collecting twice the number of relevant MS/MS data. The second factor is the use of twice the number of SCX salt fractions in the first dimension, allowing a better sample fractionation, thereby reducing the number of peptides transferred to the second chromatographic dimension per salt fraction. PMID:16224964

  18. Computational Studies of Condensed Matter Systems: Manganese Vanadium Oxide and 2D attractive Hubbard model with spin-dependent disorder

    NASA Astrophysics Data System (ADS)

    Nanguneri, Ravindra

    -dependent disorder. Further, the finite temperature phase diagram for the 2D attractive fermion Hubbard model with spin-dependent disorder is also considered within BdG mean field theory. Three types of disorder are studied. In the first, only one species is coupled to a random site energy; in the second, the two species both move in random site energy landscapes which are of the same amplitude, but different realizations; and finally, in the third, the disorder is in the hopping rather than the site energy. For all three cases we find that, unlike the case of spin-symmetric randomness, where the energy gap and average order parameter do not vanish as the disorder strength increases, a critical disorder strength exists separating distinct phases. In fact, the energy gap and the average order parameter vanish at distinct transitions, Vcgap and Vc op, allowing for a gapless superconducting (gSC) phase. The gSC phase becomes smaller with increasing temperature, until it vanishes at a temperature T*.

  19. Collagen esterification enhances the function and survival of pancreatic β cells in 2D and 3D culture systems

    SciTech Connect

    Ko, Jae Hyung; Kim, Yang Hee; Jeong, Seong Hee; Lee, Song; Park, Si-Nae; Shim, In Kyong; Kim, Song Cheol

    2015-08-07

    Collagen, one of the most important components of the extracellular matrix (ECM), may play a role in the survival of pancreatic islet cells. In addition, chemical modifications that change the collagen charge profile to a net positive charge by esterification have been shown to increase the adhesion and proliferation of various cell types. The purpose of this study was to characterize and compare the effects of native collagen (NC) and esterified collagen (EC) on β cell function and survival. After isolation by the collagenase digestion technique, rat islets were cultured with NC and EC in 2 dimensional (2D) and 3 dimensional (3D) environments for a long-term duration in vitro. The cells were assessed for islet adhesion, morphology, viability, glucose-induced insulin secretion, and mRNA expression of glucose metabolism-related genes, and visualized by scanning electron microscopy (SEM). Islet cells attached tightly in the NC group, but islet cell viability was similar in both the NC and EC groups. Glucose-stimulated insulin secretion was higher in the EC group than in the NC group in both 2D and 3D culture. Furthermore, the mRNA expression levels of glucokinase in the EC group were higher than those in the NC group and were associated with glucose metabolism and insulin secretion. Finally, SEM observation confirmed that islets had more intact component cells on EC sponges than on NC sponges. These results indicate that modification of collagen may offer opportunities to improve function and viability of islet cells. - Highlights: • We changed the collagen charge profile to a net positive charge by esterification. • Islets cultured on esterified collagen improved survival in both 2D and 3D culture. • Islets cultured on esterified collagen enhanced glucose-stimulated insulin release. • High levels of glucokinase mRNA may be associated with increased insulin release.

  20. Modeling water flow and nitrate dynamics in a plastic mulch vegetable cultivation system using HYDRUS-2D

    NASA Astrophysics Data System (ADS)

    Filipović, Vilim; Romić, Davor; Romić, Marija; Matijević, Lana; Mallmann, Fábio J. K.; Robinson, David A.

    2016-04-01

    Growing vegetables commercially requires intensive management and involves high irrigation demands and input of agrochemicals. Plastic mulch application in combination with drip irrigation is a common agricultural management technique practiced due to variety of benefits to the crop, mostly vegetable biomass production. However, the use of these techniques can result in various impacts on water and nutrient distribution in underlying soil and consequently affect nutrient leaching towards groundwater resources. The aim of this work is to estimate the effect of plastic mulch cover in combination with drip irrigation on water and nitrate dynamics in soil using HYDRUS-2D model. The field site was located in Croatian costal karst area on a Gleysol (WRB). The experiment was designed according to the split-plot design in three repetitions and was divided into plots with plastic mulch cover (MULCH) and control plots with bare soil (CONT). Each of these plots received applications of three levels of nitrogen fertilizer: 70, 140, and 210 kg per ha. All plots were equipped with drip irrigation and cropped with bell pepper (Capsicum annuum L. cv. Bianca F1). Lysimeters were installed at 90 cm depth in all plots and were used for monitoring the water and nitrate outflow. HYDRUS-2D was used for modeling the water and nitrogen outflow in the MULCH and CONT plots, implementing the proper boundary conditions. HYDRUS-2D simulated results showed good fitting to the field site observed data in both cumulative water and nitrate outflow, with high level of agreement. Water flow simulations produced model efficiency of 0.84 for CONT and 0.56 for MULCH plots, while nitrate simulations showed model efficiency ranging from 0.67 to 0.83 and from 0.70 to 0.93, respectively. Additional simulations were performed with the absence of the lysimeter, revealing faster transport of nitrates below drip line in the CONT plots, mostly because of the increased surface area subjected to precipitation

  1. Global existence and uniqueness theorem to 2-D incompressible non-resistive MHD system with non-equilibrium background magnetic field

    NASA Astrophysics Data System (ADS)

    Zhai, Cuili; Zhang, Ting

    2016-09-01

    In this article, we consider the global existence and uniqueness of the solution to the 2D incompressible non-resistive MHD system with non-equilibrium background magnetic field. Our result implies that a strong enough non-equilibrium background magnetic field will guarantee the stability of the nonlinear MHD system. Beside the classical energy method, the interpolation inequalities and the algebraic structure of the equations coming from the incompressibility of the fluid are crucial in our arguments.

  2. Longevity of duct tape in residential air distribution systems: 1-D, 2-D, and 3-D joints

    SciTech Connect

    Abushakra, Bass

    2002-05-30

    The aging tests conducted so far showed that duct tape tends to degrade in its performance as the joint it is applied to requires a geometrical description of a higher number of space dimensions (1-D, 2-D, 3-D). One-dimensional joints are the easiest to seal with duct tape, and thus the least to experience failure. Two-dimensional joints, such as the flexible duct core-to-collar joints tested in this study, are less likely to fail than three-dimensional collar-to-plenum joints, as the shrinkage could have a positive effect in tightening the joint. Three-dimensional joints are the toughest to seal and the most likely to experience failure. The 2-D flexible duct core-to-collar joints passed the six-month period of the aging test in terms of leakage, but with the exception of the foil-butyl tape, showed degradation in terms hardening, brittleness, partial peeling, shrinkage, wrinkling, delamination of the tape layers, flaking, cracking, bubbling, oozing and discoloration. The baking test results showed that the failure in the duct tape joints could be attributed to the type of combination of the duct tape and the material it is applied to, as the duct tape behaves differently with different substrates. Overall, the foil-butyl tape (Tape 4) had the best results, while the film tape (Tape 3) showed the most deterioration. The conventional duct tapes tested (Tape 1 and Tape 2) were between these two extremes, with Tape 2 performing better than Tape 1. Lastly, we found that plastic straps became discolored and brittle during the tests, and a couple of straps broke completely. Therefore, we recommend that clamping the duct-taped flexible core-to-collar joints should be done with metallic adjustable straps.

  3. Landau level spin diode in a GaAs two dimensional hole system

    NASA Astrophysics Data System (ADS)

    Klochan, O.; Hamilton, A. R.; das Gupta, K.; Sfigakis, F.; Beere, H. E.; Ritchie, D. A.

    2015-03-01

    We have fabricated and characterized a Landau level spin diode in a GaAs two-dimensional hole system. We used the spin diode to probe the hyperfine coupling between hole and nuclear spins and found no detectable net nuclear spin polarization, indicating that hole-nuclear spin flip-flop processes are suppressed by at least factor of 50 compared to GaAs electron systems.

  4. Aniso2D

    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.

  5. 2D THD and 3D TEHD analysis of large spindle supported thrust bearings with pins and double layer system used in the three gorges hydroelectric generators

    NASA Astrophysics Data System (ADS)

    Huang, B.; Wu, Z. D.; Wu, J. L.; Wang, L. Q.

    2012-11-01

    A 2D THD model and a 3DTEHD model for large spindle supported thrust bearings were set up and used to analyze the lubrication performance of the Three Gorges test thrust beating withpins and double layer system developed by Alstom Power. The finite difference method was employed to solve the THD model, and the thermal-elasticdeformations in the pad and runner were obtained by the finite element software ANSYS11.0. The data transfer between the THD model and ANSYS11.0 was carried out automatically by an interface program.A detailed comparison between the experimental results and numerical predictions by the two different modelsset up in this paper was carried out. Poor agreement has been found between the theoretical results obtained by 2D THD model and experimental data, while 3D TEHD provides fairly good agreement, confirming the importance of thermal effects and thermal-elastic deformations in both pad and runner.

  6. Black hole-jet systems: From blazars to microquasars

    NASA Astrophysics Data System (ADS)

    Xue, Yongquan

    Understanding black holes is one of the most intriguing and important topics in high energy astrophysics. Many astronomical black hole systems are known to contain three basic components: a black hole, an accretion disk, and a pair of collimated jets that are likely coupled physically to the accretion disk. For this thesis work, the focus is on two classes of black hole-jet systems, known as blazars and microquasars. There is growing evidence that the central engines in both types of systems are qualitatively similar. Collectively, they may, therefore, provide an excellent laboratory for studying common physical processes over a vast range of physical scales. Although both types of systems have been studied extensively, there are still many outstanding issues. The goal of this thesis work is to cast light on some of these important issues. First, to understand the energetics of the flaring phenomenon in blazars, it is necessary to get a handle on the size of the emitting region. An effective way to do so is to quantify timescales over which a source varies. I systematically studied X-ray flaring activities of the TeV blazar Mrk 501 and found flares over a wide range of timescale, with the most rapid one lasting for only about 800 s, which is the shortest ever seen in this system. The latter sets an upper limit of ~ 2.4 × 10^14 cm (i.e., 800 light seconds) on the size of the region that produces the flare, which is already comparable to the characteristic size of the black hole (of ~ 10 9 [Special characters omitted.] ). Second, a related question is what causes the observed flares in blazars. To this end, I studied X-ray spectral evolution of TeV blazars Mrk 421 and Mrk 501 during individual flares that last for a few days. Such a study has become possible only recently, with high-quality X-ray data taken during very active periods of the sources. I fitted the time-resolved X-ray spectra with a synchrotron model and found that, in order to account for the observed

  7. SU-E-CAMPUS-T-05: Preliminary Results On a 2D Dosimetry System Based On the Optically Stimulated Luminescence of Al2O3

    SciTech Connect

    Ahmed, M; Eller, S; Yukihara, E; Schnell, E; Ahmad, S; Akselrod, M; Hanson, O

    2014-06-15

    Purpose: To develop a precise 2D dose mapping technique based on the optically stimulated luminescence (OSL) from Al{sub 2}O{sub 3} films for medical applications. Methods: A 2D laser scanning reader was developed using fast F{sup +}-center (lifetime of <7 ns) and slow F-center (lifetime of 35 ms) OSL emission from newly developed Al{sub 2}O{sub 3} films (Landauer Inc.). An algorithm was developed to correct images for both material and system properties. Since greater contribution of the F??-center emission in the recorded signal increases the readout efficiency and robustness of image corrections, Al{sub 2}O{sub 3}:C,Mg film samples are being investigated in addition to Al{sub 2}O{sub 3}:C samples. Preliminary investigations include exposure of the films to a 6 MV photon beam at 10 cm depth in solid water phantom with an SSD of 100 cm, using a 10 cm × 10 cm flat field or a 4 cm × 4 cm field with a 60° wedge filter. Kodak EDR2 radiographic film and EBT2 Gafchromic film were also exposed for comparison. Results: The results indicate that the algorithm is able to correct images and calculate 2D dose. For the wedge field irradiation, the calculated dose at the center of the field was 0.9 Gy for Al{sub 2}O{sub 3}:C and 0.87 Gy for Al{sub 2}O{sub 3}:C,Mg, whereas, the delivered dose was 0.95 Gy. A good qualitative agreement of the dose profiles was obtained between the OSL films and EDR2 and EBT2 films. Laboratory tests using a beta source suggest that a large dynamic range (10{sup −2}−10{sup 2} Gy) can be achieved using this technique. Conclusion: A 2D dosimetry system and an in-house image correction algorithm were developed for 2D film dosimetry in medical applications. The system is in the preliminary stage of development, but the data demonstrates the feasibility of this approach. This work was supported by Landauer, Inc.

  8. Mesh2d

    SciTech Connect

    Greg Flach, Frank Smith

    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 assigns an integer material type to each grid cell, mtyp(i,j), in a user-specified manner. The complete grid is specified through three separate input files defining the x(i), y(i,j), and mtyp(i,j) variations.

  9. Mesh2d

    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

  10. Registration of 2D C-Arm and 3D CT Images for a C-Arm Image-Assisted Navigation System for Spinal Surgery.

    PubMed

    Chang, Chih-Ju; Lin, Geng-Li; Tse, Alex; Chu, Hong-Yu; Tseng, Ching-Shiow

    2015-01-01

    C-Arm image-assisted surgical navigation system has been broadly applied to spinal surgery. However, accurate path planning on the C-Arm AP-view image is difficult. This research studies 2D-3D image registration methods to obtain the optimum transformation matrix between C-Arm and CT image frames. Through the transformation matrix, the surgical path planned on preoperative CT images can be transformed and displayed on the C-Arm images for surgical guidance. The positions of surgical instruments will also be displayed on both CT and C-Arm in the real time. Five similarity measure methods of 2D-3D image registration including Normalized Cross-Correlation, Gradient Correlation, Pattern Intensity, Gradient Difference Correlation, and Mutual Information combined with three optimization methods including Powell's method, Downhill simplex algorithm, and genetic algorithm are applied to evaluate their performance in converge range, efficiency, and accuracy. Experimental results show that the combination of Normalized Cross-Correlation measure method with Downhill simplex algorithm obtains maximum correlation and similarity in C-Arm and Digital Reconstructed Radiograph (DRR) images. Spine saw bones are used in the experiment to evaluate 2D-3D image registration accuracy. The average error in displacement is 0.22 mm. The success rate is approximately 90% and average registration time takes 16 seconds. PMID:27018859

  11. Theory of spatiotemporally resolved spectroscopy for phase-separation dynamics in electron-hole systems

    NASA Astrophysics Data System (ADS)

    Ishikawa, Akira

    2013-02-01

    Phase separation such as the formation of electron-hole droplets has been observed in semiconductor electron-hole systems. In such conventional experiments, the information averaged in real space was obtained. However, in recent years, optical-near-field techniques have enabled us to acquire spatial information. In this study, I propose a theoretical formulation of spatiotemporal dynamics and spatiotemporally resolved optical response of the gas-liquid phase separation in electron-hole systems. In addition, the nature of the nonequilibrium open system is an essential point in electron-hole systems. Therefore, I investigate the effect of the finite lifetime of electron-hole pairs on phase-separation dynamics. Contribution to the Topical Issue "Excitonic Processes in Condensed Matter, Nanostructured and Molecular Materials", edited by Maria Antonietta Loi, Jasper Knoester and Paul H. M. van Loosdrecht.

  12. Development of CAD/CAM System for Cross Section’s Changing Hole Electrical Discharge Machining

    NASA Astrophysics Data System (ADS)

    Ishida, Tohru; Ishiguro, Eiki; Kita, Masahiko; Nakamoto, Keiichi; Takeuchi, Yoshimi

    This study deals with the development of a new CAD/CAM system for fabricating holes whose cross sections change variously. The cross sections of machined holes are generally constant. The limitations in the shapes of holes that can be machined make obstacles in the design stage of industrial products. A new device that utilizes electrical discharge machining has been developed that can create holes with various cross sections to solve this problem. However, it has been impossible to put the device into practical use since there has been no software that has enabled the designed shapes to be easily machined. Therefore, we aimed at developing a new CAD/CAM system for machining the beforehand designed holes with changing cross sections by using the device. As the first step in developing the CAD/CAM system, the post processor in the CAM system is formulated in this paper.

  13. Gate control of low-temperature spin dynamics in two-dimensional hole systems

    NASA Astrophysics Data System (ADS)

    Kugler, M.; Andlauer, T.; Korn, T.; Wagner, A.; Fehringer, S.; Schulz, R.; Kubová, M.; Gerl, C.; Schuh, D.; Wegscheider, W.; Vogl, P.; Schüller, C.

    2009-07-01

    We have investigated spin and carrier dynamics of resident holes in high-mobility two-dimensional hole systems in GaAs/Al0.3Ga0.7As single-quantum wells at temperatures down to 400 mK. Time-resolved Faraday and Kerr rotation as well as time-resolved photoluminescence spectroscopy are utilized in our study. We observe long-lived hole-spin dynamics that are strongly temperature dependent, indicating that in-plane localization is crucial for hole-spin coherence. By applying a gate voltage, we are able to tune the observed hole g factor by more than 50%. Calculations of the hole g tensor as a function of the applied bias show excellent agreement with our experimental findings.

  14. High-throughput 2D root system phenotyping platform facilitates genetic analysis of root growth and development

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High-throughput phenotyping of root systems requires a combination of specialized techniques and adaptable plant growth, root imaging and software tools. A custom phenotyping platform was designed to capture images of whole root systems, and novel software tools were developed to process and analyz...

  15. A mathematical model for 2D heat transfer dynamics in fluid systems with localized sink of magmatic fluid into local fractured zones above the top of crystallizing intrusions

    NASA Astrophysics Data System (ADS)

    Sharapov, V. N.; Cherepanov, A. N.; Popov, V. N.; Bykova, V. G.

    2012-11-01

    A model describing two-dimensional (2D) dynamics of heat transfer in the fluid systems with a localized sink of a magmatic fluid into local fractured zones above the roof of crystallizing crustal intrusions is suggested. Numerical modeling of the migration of the phase boundaries in 2D intrusive chambers under retrograde boiling of magma with relatively high initial water content in the melt shows that, depending on the character of heat dissipation from a magmatic fluid into the host rock, two types of fluid magmatic systems can arise. (1) At high heat losses, the zoning of fluidogenic ore formation is determined by the changes in temperature of the rocks within the contact aureole of the intrusive bodies. These temperature variations are controlled by the migration of the phase boundaries in the cooling melt towards the center of the magmatic bodies from their contacts. (2) In the case of a localized sink of the magmatic fluid in different parts of the top of the intrusive chambers, a specific characteristic scenario of cooling of the magmatic bodies is probably implemented. In 2D systems with a heat transfer coefficient α k < 5 × 104 W/m2 K, an area with quasi-stationary phase boundaries develops close to the region of fluid drainage through the fractured zone in the intrusion. Therefore, as the phase boundaries contract to the sink zone of a fluid, specific thermal tubes arise, whose characteristics depend on the width of the fluid-conductive zone and the heat losses into the side rocks. (3) The time required for the intrusion to solidify varies depending on the particular position of the fluid conductor above the top of the magmatic body.

  16. Stabilizing a solution of the 2D Navier-Stokes system in the exterior of a bounded domain by means of a control on the boundary

    SciTech Connect

    Gorshkov, Aleksei V

    2012-09-30

    The problem of stabilizing a solution of the 2D Navier-Stokes system defined in the exterior of a bounded domain with smooth boundary is investigated. For a given initial velocity field a control on the boundary of the domain must be constructed such that the solution stabilizes to a prescribed vortex solution or trivial solution at the rate of 1/t{sup k}. On the way, related questions are investigated, concerning the behaviour of the spectrum of an operator under a relatively compact perturbation and the existence of attracting invariant manifolds. Bibliography: 21 titles.

  17. AN UPPER LIMIT TO THE VELOCITY DISPERSION OF RELAXED STELLAR SYSTEMS WITHOUT MASSIVE BLACK HOLES

    SciTech Connect

    Miller, M. Coleman; Davies, Melvyn B.

    2012-08-10

    Massive black holes have been discovered in all closely examined galaxies with high velocity dispersion. The case is not as clear for lower-dispersion systems such as low-mass galaxies and globular clusters. Here we suggest that above a critical velocity dispersion {approx}40 km s{sup -1}, massive central black holes will form in relaxed stellar systems at any cosmic epoch. This is because above this dispersion primordial binaries cannot support the system against deep core collapse. If, as previous simulations show, the black holes formed in the cluster settle to produce a dense subcluster, then given the extremely high densities reached during core collapse the holes will merge with each other. For low velocity dispersions and hence low cluster escape speeds, mergers will typically kick out all or all but one of the holes due to three-body kicks or the asymmetric emission of gravitational radiation. If one hole remains, it will tidally disrupt stars at a high rate. If none remain, one is formed after runaway collisions between stars, and then it tidally disrupts stars at a high rate. The accretion rate after disruption is many orders of magnitude above Eddington. If, as several studies suggest, the hole can accept matter at that rate because the generated radiation is trapped and advected, then it will grow quickly and form a massive central black hole.

  18. Accuracy and precision of a custom camera-based system for 2D and 3D motion tracking during speech and nonspeech motor tasks

    PubMed Central

    Feng, Yongqiang; Max, Ludo

    2014-01-01

    Purpose Studying normal or disordered motor control requires accurate motion tracking of the effectors (e.g., orofacial structures). The cost of electromagnetic, optoelectronic, and ultrasound systems is prohibitive for many laboratories, and limits clinical applications. For external movements (lips, jaw), video-based systems may be a viable alternative, provided that they offer high temporal resolution and sub-millimeter accuracy. Method We examined the accuracy and precision of 2D and 3D data recorded with a system that combines consumer-grade digital cameras capturing 60, 120, or 240 frames per second (fps), retro-reflective markers, commercially-available computer software (APAS, Ariel Dynamics), and a custom calibration device. Results Overall mean error (RMSE) across tests was 0.15 mm for static tracking and 0.26 mm for dynamic tracking, with corresponding precision (SD) values of 0.11 and 0.19 mm, respectively. The effect of frame rate varied across conditions, but, generally, accuracy was reduced at 240 fps. The effect of marker size (3 vs. 6 mm diameter) was negligible at all frame rates for both 2D and 3D data. Conclusion Motion tracking with consumer-grade digital cameras and the APAS software can achieve sub-millimeter accuracy at frame rates that are appropriate for kinematic analyses of lip/jaw movements for both research and clinical purposes. PMID:24686484

  19. Accuracy and precision of a custom camera-based system for 2-d and 3-d motion tracking during speech and nonspeech motor tasks.

    PubMed

    Feng, Yongqiang; Max, Ludo

    2014-04-01

    PURPOSE Studying normal or disordered motor control requires accurate motion tracking of the effectors (e.g., orofacial structures). The cost of electromagnetic, optoelectronic, and ultrasound systems is prohibitive for many laboratories and limits clinical applications. For external movements (lips, jaw), video-based systems may be a viable alternative, provided that they offer high temporal resolution and submillimeter accuracy. METHOD The authors examined the accuracy and precision of 2-D and 3-D data recorded with a system that combines consumer-grade digital cameras capturing 60, 120, or 240 frames per second (fps), retro-reflective markers, commercially available computer software (APAS, Ariel Dynamics), and a custom calibration device. RESULTS Overall root-mean-square error (RMSE) across tests was 0.15 mm for static tracking and 0.26 mm for dynamic tracking, with corresponding precision (SD) values of 0.11 and 0.19 mm, respectively. The effect of frame rate varied across conditions, but, generally, accuracy was reduced at 240 fps. The effect of marker size (3- vs. 6-mm diameter) was negligible at all frame rates for both 2-D and 3-D data. CONCLUSION Motion tracking with consumer-grade digital cameras and the APAS software can achieve submillimeter accuracy at frame rates that are appropriate for kinematic analyses of lip/jaw movements for both research and clinical purposes. PMID:24686484

  20. Conjugate Fermi holes and its manifestation in He-like systems

    SciTech Connect

    Sako, Tokuei

    2015-12-31

    The structure of genuine and conjugate Fermi holes in two-electron atomic systems, namely He and He-like atomic ions, has been studied relying on accurate full configuration interaction wave functions. The standard Fermi hole exists in the vicinity of region in the two-electron coordinate space satisfying the well-known condition, r{sub 1} = r{sub 2}, while the conjugate Fermi hole exists in the vicinity of region close to this genuine Fermi hole but satisfying r{sub 1} ≠ r{sub 2} instead of r{sub 1} = r{sub 2}. Existence of these holes has shown to give an insightful interpretation of the origin of the first Hund rule and of the anomalously strong angular correlation manifested in the series of the singlet-triplet pair of singly-excited states of the aforementioned systems.

  1. Conjugate Fermi holes and its manifestation in He-like systems

    NASA Astrophysics Data System (ADS)

    Sako, Tokuei

    2015-12-01

    The structure of genuine and conjugate Fermi holes in two-electron atomic systems, namely He and He-like atomic ions, has been studied relying on accurate full configuration interaction wave functions. The standard Fermi hole exists in the vicinity of region in the two-electron coordinate space satisfying the well-known condition, r1 = r2, while the conjugate Fermi hole exists in the vicinity of region close to this genuine Fermi hole but satisfying r1 ≠ r2 instead of r1 = r2. Existence of these holes has shown to give an insightful interpretation of the origin of the first Hund rule and of the anomalously strong angular correlation manifested in the series of the singlet-triplet pair of singly-excited states of the aforementioned systems.

  2. 3-D and quasi-2-D discrete element modeling of grain commingling in a bucket elevator boot system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Unwanted grain commingling impedes new quality-based grain handling systems and has proven to be an expensive and time consuming issue to study experimentally. Experimentally validated models may reduce the time and expense of studying grain commingling while providing additional insight into detail...

  3. Fault-tolerant quantum computation and communication on a distributed 2D array of small local systems

    SciTech Connect

    Fujii, K.; Yamamoto, T.; Imoto, N.; Koashi, M.

    2014-12-04

    We propose a scheme for distributed quantum computation with small local systems connected via noisy quantum channels. We show that the proposed scheme tolerates errors with probabilities ∼30% and ∼ 0.1% in quantum channels and local operations, respectively, both of which are improved substantially compared to the previous works.

  4. Electronic structure and hole-hole coupling in YBa sub 2 Cu sub 3 O sub 7 minus x systems

    SciTech Connect

    Lopez-Aguilar, F.; Costa-Quintana, J. )

    1990-09-01

    The electronic structure of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} for {ital x}=0, has been determined by means of an approximation to the self-energy for Hubbard systems with two channels for the localization ({ital p} and {ital d}). This self-energy contains the unrestricted Hartree-Fock terms and the dynamically screened exchange. The calculated electronic structure presents a different ionization state for the atoms of the CuO{sub 2} sheets with respect to the CuO{sub 3} chain. For increasing {ital x} values, electron transferences between O-O, Cu-Cu, and Cu-O atoms are produced. These electronic transferences provide holes to the CuO{sub 2} sheets in symmetries {ital d}{sub {ital x}{sup 2}{minus}{ital y}{sup 2}} of Cu(2) and {ital p}{sub {ital x}} and {ital p}{sub {ital y}} of O(2) and O(3). These holes suffer interatomic screening, which produces coupling for determined densities of holes and widths of the bands. The main parameter for obtaining superconductivity is the lower limit of the frequency interval for which the interatomic {ital W}{sub {ital p}{ital d}}({omega}) is negative. This frequency has to be sufficiently less than a critical cutoff frequency. We discuss the conditions of the electronic structure for obtaining high-{Tc} superconductivity.

  5. An admissibility and asymptotic-preserving scheme for systems of conservation laws with source term on 2D unstructured meshes

    NASA Astrophysics Data System (ADS)

    Blachère, F.; Turpault, R.

    2016-06-01

    The objective of this work is to design explicit finite volumes schemes for specific systems of conservations laws with stiff source terms, which degenerate into diffusion equations. We propose a general framework to design an asymptotic preserving scheme, that is stable and consistent under a classical hyperbolic CFL condition in both hyperbolic and diffusive regime, for any two-dimensional unstructured mesh. Moreover, the scheme developed also preserves the set of admissible states, which is mandatory to keep physical solutions in stiff configurations. This construction is achieved by using a non-linear scheme as a target scheme for the diffusive equation, which gives the form of the global scheme for the complete system of conservation laws. Numerical results are provided to validate the scheme in both regimes.

  6. 2D materials. Graphene, related two-dimensional crystals, and hybrid systems for energy conversion and storage.

    PubMed

    Bonaccorso, Francesco; Colombo, Luigi; Yu, Guihua; Stoller, Meryl; Tozzini, Valentina; Ferrari, Andrea C; Ruoff, Rodney S; Pellegrini, Vittorio

    2015-01-01

    Graphene and related two-dimensional crystals and hybrid systems showcase several key properties that can address emerging energy needs, in particular for the ever growing market of portable and wearable energy conversion and storage devices. Graphene's flexibility, large surface area, and chemical stability, combined with its excellent electrical and thermal conductivity, make it promising as a catalyst in fuel and dye-sensitized solar cells. Chemically functionalized graphene can also improve storage and diffusion of ionic species and electric charge in batteries and supercapacitors. Two-dimensional crystals provide optoelectronic and photocatalytic properties complementing those of graphene, enabling the realization of ultrathin-film photovoltaic devices or systems for hydrogen production. Here, we review the use of graphene and related materials for energy conversion and storage, outlining the roadmap for future applications. PMID:25554791

  7. Staring 2-D hadamard transform spectral imager

    DOEpatents

    Gentry, Stephen M.; Wehlburg, Christine M.; Wehlburg, Joseph C.; Smith, Mark W.; Smith, Jody L.

    2006-02-07

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

  8. Comparison of the Expression of Hepatic Genes by Human Wharton’s Jelly Mesenchymal Stem Cells Cultured in 2D and 3D Collagen Culture Systems

    PubMed Central

    Khodabandeh, Zahra; Vojdani, Zahra; Talaei-Khozani, Tahereh; Jaberipour, Mansoureh; Hosseini, Ahmad; Bahmanpour, Soghra

    2016-01-01

    Background: Human Wharton’s jelly mesenchymal stem cells (HWJMSCs) express liver-specific markers such as albumin, alpha-fetoprotein, cytokeratin-19, cytokeratin-18, and glucose-6-phosphatase. Therefore, they can be considered as a good source for cell replacement therapy for liver diseases. This study aimed to evaluate the effects of various culture systems on the hepatocyte-specific gene expression pattern of naïve HWJMSCs. Methods: HWJMSCs were characterized as MSCs by detecting the surface CD markers and capability to differentiate toward osteoblast and adipocyte. HWJMSCs were cultured in 2D collagen films and 3D collagen scaffolds for 21 days and were compared to control cultures. Real time RT-PCR was used to evaluate the expression of liver-specific genes. Results: The HWJMSCs which were grown on non-coated culture plates expressed cytokeratin-18 and -19, alpha-fetoprotein, albumin, glucose-6-phosphatase, and claudin. The expression of the hepatic nuclear factor 4 (HNF4) was very low. The cells showed a significant increase in caludin expression when they cultured in 3D collagen scaffolds compared to the conventional monolayer culture and 2D collagen scaffold. Conclusion: Various culture systems did not influence on hepatocyte specific marker expression by HWJMSCs, except for claudin. The expression of claudin showed that 3D collagen scaffold provided the extracellular matrix for induction of the cells to interconnect with each other. PMID:26722142

  9. Analysis of bell-shape negative giant-magnetoresistance in high mobility GaAs/AlGaAs 2D electron systems using multi-conduction model

    NASA Astrophysics Data System (ADS)

    Samaraweera, Rasanga; Liu, Han-Chun; Wegscheider, Werner; Mani, Ramesh

    Recent advancements in the growth techniques of the GaAs/AlGaAs two dimensional electron system (2DES) routinely yield high quality heterostructures with enhanced physical and electrical properties, including devices with 2D electron mobilities well above 107 cm2/Vs. These improvements have opened new pathways to study interesting physical phenomena associated with the 2D electron system. Negative giant-magnetoresistance (GMR) is one such phenomenon which can observed in the high mobility 2DES. However, the negative GMR in the GaAs/AlGaAs 2DES is still not fully understood. In this contribution, we present an experimental study of the bell-shape negative GMR in high mobility GaAs/AlGaAs devices and quantitatively analyze the results utilizing the multi-conduction model. The multi-conduction model includes interesting physical characteristics such as negative diagonal conductivity, non-vanishing off-diagonal conductivity, etc. The aim of the study is to examine GMR over a wider experimental parameter space and determine whether the multi-conduction model serves to describe the experimental results.

  10. Simulation of decay heat removal by natural convection in a pool type fast reactor model-ramona-with coupled 1D/2D thermal hydraulic code system

    SciTech Connect

    Kasinathan, N.; Rajakumar, A.; Vaidyanathan, G.; Chetal, S.C.

    1995-09-01

    Post shutdown decay heat removal is an important safety requirement in any nuclear system. In order to improve the reliability of this function, Liquid metal (sodium) cooled fast breeder reactors (LMFBR) are equipped with redundant hot pool dipped immersion coolers connected to natural draught air cooled heat exchangers through intermediate sodium circuits. During decay heat removal, flow through the core, immersion cooler primary side and in the intermediate sodium circuits are also through natural convection. In order to establish the viability and validate computer codes used in making predictions, a 1:20 scale experimental model called RAMONA with water as coolant has been built and experimental simulation of decay heat removal situation has been performed at KfK Karlsruhe. Results of two such experiments have been compiled and published as benchmarks. This paper brings out the results of the numerical simulation of one of the benchmark case through a 1D/2D coupled code system, DHDYN-1D/THYC-2D and the salient features of the comparisons. Brief description of the formulations of the codes are also included.

  11. Fitting of Diverging Thermoelectric Power in a Strongly Interacting 2D Electron System of Si-MOSFETs

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Tak

    2013-03-01

    The diverging-effective mass (DEM) in a metallic system is evidence of strong correlation between fermions in strongly correlated systems. The identification of the DEM still remains to be revealed The effective mass, m* =mo/(1-ρ4) where ρ is band filling helps clarify the diverging thermoelectric power, S, measured in inhomogeneous Si-MOSFET systems. As a carrier density ns decreases, S increases rapidly This is regarded as the metal-insulator transition (MIT) near nc ~ 79x10-1cm-2, where nc is about 0.02% to nSi ~ 3.4x10-14cm-2 in Si. This can be solved in assuming that ρ = nc/ns increases as ns decreases. nc is an excited(doped) carrier density in the semiconductor induced by gate and can be also regarded as a metallic carrier density, that is, nc ≡ nseminon = nmetal. ns is given as ntot ≡ ns = nc + nseminon where nseminon is a carrier density in a nonmetallic phase. The carrier density measured by Hall effect is the sum of carriers both induced by gate field and generated by MIT. Moreover, a larger metallic phase is not made due to a conducting path in the field-effect structure after a metallic phase is formed. Thus, increasing ns indicates increasing nnon; this corresponds to an over-doping to increase inhomogeneity. It's fitting is given from S = (απ3 kB2T/3e)(1/EF)= (α 8π3kB2T/3h2)(m*/e*nc) =So(1/ ρ) (1/(1-ρ4)) , where e* = ρ e, ρ = nc/ns, T =0.8K, m* =mo/(1-ρ4), α = 0.6, and So = (α 8π3kB2T/3h2)(mo/enc) ~12.36 are used. The data S are closely fitted by m*

  12. Off-axis electron holography with a dual-lens imaging system and its usefulness in 2-D potential mapping of semiconductor devices.

    PubMed

    Wang, Y Y; Kawasaki, M; Bruley, J; Gribelyuk, M; Domenicucci, A; Gaudiello, J

    2004-11-01

    A variable magnification electron holography, applicable for two-dimensional (2-D) potential mapping of semiconductor devices, employing a dual-lens imaging system is described. Imaging operation consists of a virtual image formed by the objective lens (OL) and a real image formed in a fixed imaging plane by the objective minilens. Wide variations in field of view (100-900 nm) and fringe spacing (0.7-6 nm) were obtained using a fixed biprism voltage by varying the total magnification of the dual OL system. The dual-lens system allows fringe width and spacing relative to the object to be varied roughly independently from the fringe contrast, resulting in enhanced resolution and sensitivity. The achievable fringe width and spacing cover the targets needed for devices in the semiconductor technology road map from the 350 to 45 nm node. Two-D potential maps for CMOS devices with 220 and 70 nm gate lengths were obtained. PMID:15450653

  13. Neutron scattering study of a quasi-2D spin-1/2 dimer system Piperazinium Hexachlorodicuprate under hydrostatic pressure

    SciTech Connect

    Hong, Tao; Stock, C.; Cabrera, I.; Broholm, C.; Qiu, Y.; Leao, J. B.; Poulton, S. J.; Copley, J.R.D.

    2010-01-01

    We report inelastic neutron scattering study of a quasi-two-dimensional S=1/2 dimer system piperazinium hexachlorodicuprate under hydrostatic pressure. The spin gap {Delta} becomes softened with the increase of the hydrostatic pressure up to P = 9.0 kbar. The observed threefold degenerate triplet excitation at P = 6.0 kbar is consistent with the theoretical prediction and the bandwidth of the dispersion relation is unaffected within the experimental uncertainty. At P = 9.0 kbar the spin gap is reduced to {Delta} = 0.55 meV from {Delta} = 1.0 meV at ambient pressure.

  14. Flaring Black Hole Accretion Disk in the Binary System V404 Cygni

    NASA Video Gallery

    On June 15, NASA's Swift caught the onset of a rare X-ray outburst from a stellar-mass black hole in the binary system V404 Cygni. Astronomers around the world are watching the event. In this syste...

  15. Effects of fluid flow and calcium phosphate coating on human bone marrow stromal cells cultured in a defined 2D model system.

    PubMed

    Scaglione, S; Wendt, D; Miggino, S; Papadimitropoulos, A; Fato, M; Quarto, R; Martin, I

    2008-08-01

    In this study, we investigated the effect of the long-term (10 days) application of a defined and uniform level of fluid flow (uniform shear stress of 1.2 x 10(-3) N/m(2)) on human bone marrow stromal cells (BMSC) cultured on different substrates (i.e., uncoated glass or calcium phosphate coated glass, Osteologictrade mark) in a 2D parallel plate model. Both exposure to flow and culture on Osteologic significantly reduced the number of cell doublings. BMSC cultured under flow were more intensely stained for collagen type I and by von Kossa for mineralized matrix. BMSC exposed to flow displayed an increased osteogenic commitment (i.e., higher mRNA expression of cbfa-1 and osterix), although phenotype changes in response to flow (i.e., mRNA expression of osteopontin, osteocalcin and bone sialoprotein) were dependent on the substrate used. These findings highlight the importance of the combination of physical forces and culture substrate to determine the functional state of differentiating osteoblastic cells. The results obtained using a simple and controlled 2D model system may help to interpret the long-term effects of BMSC culture under perfusion within 3D porous scaffolds, where multiple experimental variables cannot be easily studied independently, and shear stresses cannot be precisely computed. PMID:17969030

  16. A close-pair binary in a distant triple supermassive black hole system.

    PubMed

    Deane, R P; Paragi, Z; Jarvis, M J; Coriat, M; Bernardi, G; Fender, R P; Frey, S; Heywood, I; Klöckner, H-R; Grainge, K; Rumsey, C

    2014-07-01

    Galaxies are believed to evolve through merging, which should lead to some hosting multiple supermassive black holes. There are four known triple black hole systems, with the closest black hole pair being 2.4 kiloparsecs apart (the third component in this system is at 3 kiloparsecs), which is far from the gravitational sphere of influence (about 100 parsecs for a black hole with mass one billion times that of the Sun). Previous searches for compact black hole systems concluded that they were rare, with the tightest binary system having a separation of 7 parsecs (ref. 10). Here we report observations of a triple black hole system at redshift z = 0.39, with the closest pair separated by about 140 parsecs and significantly more distant from Earth than any other known binary of comparable orbital separation. The effect of the tight pair is to introduce a rotationally symmetric helical modulation on the structure of the large-scale radio jets, which provides a useful way to search for other tight pairs without needing extremely high resolution observations. As we found this tight pair after searching only six galaxies, we conclude that tight pairs are more common than hitherto believed, which is an important observational constraint for low-frequency gravitational wave experiments. PMID:24990745

  17. Static binary systems of extreme charged black holes

    NASA Astrophysics Data System (ADS)

    Cabrera-Munguia, I.; Manko, V. S.; Ruiz, E.

    2010-12-01

    The extreme limit of the double-Reissner-Nordström spacetime results in two particular solutions. The first one is the Majumdar-Papapetrou solution which describes two charged non-rotating extreme black holes in neutral equilibrium, the individual charges being equal to the respective masses. The second one is identified as the Bonnor solution whose constituents cannot be in equilibrium and are separated by a strut, their charges having opposite signs and exceeding the respective masses in absolute value.

  18. Microtubes and corrugations fabricated from strained ZnTe/CdHgTe/HgTe/CdHgTe heterofilms with 2D electron-hole gas in the HgTe quantum well

    NASA Astrophysics Data System (ADS)

    Mutilin, S. V.; Soots, R. A.; Vorob'ev, A. B.; Ikusov, D. G.; Mikhailov, N. N.; Prinz, V. Ya

    2014-07-01

    Variously shaped shells were fabricated from strained ZnTe/CdTe/CdHgTe/HgTe/CdHgTe heterofilms that contained a HgTe quantum well populated simultaneously with electrons and holes. The radius of curvature of formed tubes proved to be 12 µm and the period of corrugations about 20 µm. Such a curvature induces a 1.2% deformation in the HgTe layer sufficient for the occurrence of notable band-edge shifts in this layer and causes a transition of the band structure from a semiconductor to a semi-metal state. Curved HgTe-based films offer potential in studying surfaces where topological insulating states are interfaced with semiconductor states.

  19. High-precision automatic online measurement system of engine block top surface holes

    NASA Astrophysics Data System (ADS)

    Yongqiang, Shi; Changku, Sun; Yukun, Ma; Hongxu, Duan; Peng, Wang

    2012-05-01

    The measurement of holes in the engine block top surface determines the general coupling effect of the engine. All of these holes are strictly restricted by the requirements of the dimensional tolerance and the geometrical tolerance, which determines the final engine quality. At present, these holes are measured mostly by the coordinate measuring machine (CMM) in the production line, and meeting the industry demands of automation, rapidity, and online testing with the method is difficult. A new rapid solution measuring the holes in the engine block top surface is proposed, which is based on the combination of multiple visual sensors. The flexible location method of the block is designed, and the global data fusion model based on multiple visual sensors is studied. Finally, the unified correction model of the lens distortion and the system inclination is proposed, and a revised system model with more precision is researched. The CMM measures the holes sizes and the spatial relationship between holes, and the data obtained are substituted into the global data fusion model to complete the system on-site rapid calibration. The experimental results show that the scheme is feasible. The measurement system can meet the production line needs of intelligence, rapidity, and high precision.

  20. Adiabatic growth of a black hole in a rotating stellar system

    NASA Technical Reports Server (NTRS)

    Lee, Man Hoi; Goodman, Jeremy

    1989-01-01

    The consequences of slowly adding a massive black hole to the center of a rotating stellar system are considered. Although both the rotation velocity V and the velocity dispersion sigma increase when the black hole is added, the rotation velocity increases faster. The effect goes in the right direction but is too gradual to explain the V/sigma profiles recently observed in several galactic nuclei.

  1. 2D/3D Image fusion for accurate target localization and evaluation of a mask based stereotactic system in fractionated stereotactic radiotherapy of cranial lesions

    SciTech Connect

    Jin, J.-Y.; Ryu, Samuel; Faber, Kathleen; Mikkelsen, Tom; Chen Qing; Li Shidong; Movsas, Benjamin

    2006-12-15

    The purpose of this study was to evaluate the accuracy of a two-dimensional (2D) to three-dimensional (3D) image-fusion-guided target localization system and a mask based stereotactic system for fractionated stereotactic radiotherapy (FSRT) of cranial lesions. A commercial x-ray image guidance system originally developed for extracranial radiosurgery was used for FSRT of cranial lesions. The localization accuracy was quantitatively evaluated with an anthropomorphic head phantom implanted with eight small radiopaque markers (BBs) in different locations. The accuracy and its clinical reliability were also qualitatively evaluated for a total of 127 fractions in 12 patients with both kV x-ray images and MV portal films. The image-guided system was then used as a standard to evaluate the overall uncertainty and reproducibility of the head mask based stereotactic system in these patients. The phantom study demonstrated that the maximal random error of the image-guided target localization was {+-}0.6 mm in each direction in terms of the 95% confidence interval (CI). The systematic error varied with measurement methods. It was approximately 0.4 mm, mainly in the longitudinal direction, for the kV x-ray method. There was a 0.5 mm systematic difference, primarily in the lateral direction, between the kV x-ray and the MV portal methods. The patient study suggested that the accuracy of the image-guided system in patients was comparable to that in the phantom. The overall uncertainty of the mask system was {+-}4 mm, and the reproducibility was {+-}2.9 mm in terms of 95% CI. The study demonstrated that the image guidance system provides accurate and precise target positioning.

  2. Influence of self-gravity on the runaway instability of black-hole-torus systems.

    PubMed

    Montero, Pedro J; Font, José A; Shibata, Masaru

    2010-05-14

    Results from the first fully general relativistic numerical simulations in axisymmetry of a system formed by a black hole surrounded by a self-gravitating torus in equilibrium are presented, aiming to assess the influence of the torus self-gravity on the onset of the runaway instability. We consider several models with varying torus-to-black-hole mass ratio and angular momentum distribution orbiting in equilibrium around a nonrotating black hole. The tori are perturbed to induce the mass transfer towards the black hole. Our numerical simulations show that all models exhibit a persistent phase of axisymmetric oscillations around their equilibria for several dynamical time scales without the appearance of the runaway instability, indicating that the self-gravity of the torus does not play a critical role favoring the onset of the instability, at least during the first few dynamical time scales. PMID:20866955

  3. A Laser Absorption Spectroscopy System for 2D Mapping of CO2 Over Large Spatial Areas for Monitoring, Reporting and Verification of Ground Carbon Storage Sites

    NASA Astrophysics Data System (ADS)

    Dobler, J. T.; Braun, M.; Blume, N.; McGregor, D.; Zaccheo, T. S.; Pernini, T.; Botos, C.

    2014-12-01

    We will present the development of the Greenhouse gas Laser Imaging Tomography Experiment (GreenLITE). GreenLITE consists of two laser based transceivers and a number of retro-reflectors to measure differential transmission (DT) of a number of overlapping chords in a plane over the site being monitored. The transceivers use the Intensity Modulated Continuous Wave (IM-CW) approach, which is a technique that allows simultaneous transmission/reception of multiple fixed wavelength lasers and a lock-in, or matched filter, to measure amplitude and phase of the different wavelengths in the digital domain. The technique was developed by Exelis and has been evaluated using an airborne demonstrator for the past 10 years by NASA Langley Research Center. The method has demonstrated high accuracy and high precision measurements as compared to an in situ monitor tracable to WMO standards, agreeing to 0.65 ppm +/-1.7 ppm. The GreenLITE system is coupled to a cloud-based data storage and processing system that takes the measured chord data, along with auxiliary data to retrieve an average CO2 concentration per chord and which combines the chords to provide an estimate of the spatial distribution of CO2 concentration in the plane. A web-based interface allows users to view real-time CO2 concentrations and 2D concentration maps of the area being monitored. The 2D maps can be differenced as a function of time for an estimate of the flux across the plane measured by the system. The system is designed to operate autonomously from semi-remote locations with a very low maintenance cycle. Initial instrument tests, conducted in June, showed signal to noise in the measured ratio of >3000 for 10 s averages. Additional local field testing and a quantifiable field testing at the Zero Emissions Research and Technology (ZERT) site in Bozeman, MT are planned for this fall. We will present details on the instrument and software tools that have been developed, along with results from the local

  4. Monte Carlo simulation of the dose response of a novel 2D silicon diode array for use in hybrid MRI–LINAC systems

    SciTech Connect

    Gargett, Maegan Rosenfeld, Anatoly; Oborn, Brad; Metcalfe, Peter

    2015-02-15

    Purpose: MRI-guided radiation therapy systems (MRIgRT) are being developed to improve online imaging during treatment delivery. At present, the operation of single point dosimeters and an ionization chamber array have been characterized in such systems. This work investigates a novel 2D diode array, named “magic plate,” for both single point calibration and 2D positional performance, the latter being a key element of modern radiotherapy techniques that will be delivered by these systems. Methods: GEANT4 Monte Carlo methods have been employed to study the dose response of a silicon diode array to 6 MV photon beams, in the presence of in-line and perpendicularly aligned uniform magnetic fields. The array consists of 121 silicon diodes (dimensions 1.5 × 1.5 × 0.38 mm{sup 3}) embedded in kapton substrate with 1 cm pitch, spanning a 10 × 10 cm{sup 2} area in total. A geometrically identical, water equivalent volume was simulated concurrently for comparison. The dose response of the silicon diode array was assessed for various photon beam field shapes and sizes, including an IMRT field, at 1 T. The dose response was further investigated at larger magnetic field strengths (1.5 and 3 T) for a 4 × 4 cm{sup 2} photon field size. Results: The magic plate diode array shows excellent correspondence (< ± 1%) to water dose in the in-line orientation, for all beam arrangements and magnetic field strengths investigated. The perpendicular orientation, however, exhibits a dose shift with respect to water at the high-dose-gradient beam edge of jaw-defined fields [maximum (4.3 ± 0.8)% over-response, maximum (1.8 ± 0.8)% under-response on opposing side for 1 T, uncertainty 1σ]. The trend is not evident in areas with in-field dose gradients typical of IMRT dose maps. Conclusions: A novel 121 pixel silicon diode array detector has been characterized by Monte Carlo simulation for its performance inside magnetic fields representative of current prototype and proposed MRI

  5. Engineering ultralong spin coherence in two-dimensional hole systems at low temperatures

    NASA Astrophysics Data System (ADS)

    Korn, T.; Kugler, M.; Griesbeck, M.; Schulz, R.; Wagner, A.; Hirmer, M.; Gerl, C.; Schuh, D.; Wegscheider, W.; Schüller, C.

    2010-04-01

    For the realization of scalable solid-state quantum-bit systems, spins in semiconductor quantum dots (QDs) are promising candidates. A key requirement for quantum logic operations is a sufficiently long coherence time of the spin system. Recently, hole spins in III-V-based QDs were discussed as alternatives to electron spins, since the hole spin, in contrast to the electron spin, is not affected by contact hyperfine interaction with the nuclear spins. Here, we report a breakthrough in the spin coherence times of hole ensembles, confined in the so-called natural QDs, in narrow GaAs/AlGaAs quantum wells at temperatures below 500 mK. Consistently, time-resolved Faraday rotation and resonant spin amplification techniques deliver hole-spin coherence times, which approach in the low magnetic field limit values above 70 ns. The optical initialization of the hole spin polarization, as well as the interconnected electron and hole spin dynamics in our samples, are well reproduced using a rate equation model.

  6. Non-Abelian states in Fractional Quantum Hall effect in charge carrier hole systems

    NASA Astrophysics Data System (ADS)

    Simion, George; Lyanda-Geller, Yuli

    Quasiparticle excitations obeying non-Abelian statistics represent the key element of topological quantum computing. Crossing of levels and strong coupling between angular momentum and orbital motion, described by Luttinger Hamiltonian, make properties of charge carrier holes different from those of electrons. Peculiarities of hole spectrum in magnetic field provide an opportunity for controlling Landau level mixing in charge carier hole systems. In order to describe Fractional Quantum Hall effect for holes, we propose a method to map hole spectrum and wavefunctions using a spherical shell. We investigate the experimentally observed ν = 1 / 2 state in spherical geometry. Haldane pseudopotentials are computed and the effect of Landau level mixing is evaluated. Exact diagonalization of Coulomb interaction in systems with eight to fourteen holes is performed. We determine that the ground state superposition with Abelian 331 state is very small and the overlap with Moore-Read state is significant. The quasihole and quasielectron excitations are discussed. Research was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-SC0010544.

  7. GRID2D/3D: A computer program for generating grid systems in complex-shaped two- and three-dimensional spatial domains. Part 2: User's manual and program listing

    NASA Technical Reports Server (NTRS)

    Bailey, R. T.; Shih, T. I.-P.; Nguyen, H. L.; Roelke, R. J.

    1990-01-01

    An efficient computer program, called GRID2D/3D, was developed to generate single and composite grid systems within geometrically complex two- and three-dimensional (2- and 3-D) spatial domains that can deform with time. GRID2D/3D generates single grid systems by using algebraic grid generation methods based on transfinite interpolation in which the distribution of grid points within the spatial domain is controlled by stretching functions. All single grid systems generated by GRID2D/3D can have grid lines that are continuous and differentiable everywhere up to the second-order. Also, grid lines can intersect boundaries of the spatial domain orthogonally. GRID2D/3D generates composite grid systems by patching together two or more single grid systems. The patching can be discontinuous or continuous. For continuous composite grid systems, the grid lines are continuous and differentiable everywhere up to the second-order except at interfaces where different single grid systems meet. At interfaces where different single grid systems meet, the grid lines are only differentiable up to the first-order. For 2-D spatial domains, the boundary curves are described by using either cubic or tension spline interpolation. For 3-D spatial domains, the boundary surfaces are described by using either linear Coon's interpolation, bi-hyperbolic spline interpolation, or a new technique referred to as 3-D bi-directional Hermite interpolation. Since grid systems generated by algebraic methods can have grid lines that overlap one another, GRID2D/3D contains a graphics package for evaluating the grid systems generated. With the graphics package, the user can generate grid systems in an interactive manner with the grid generation part of GRID2D/3D. GRID2D/3D is written in FORTRAN 77 and can be run on any IBM PC, XT, or AT compatible computer. In order to use GRID2D/3D on workstations or mainframe computers, some minor modifications must be made in the graphics part of the program; no

  8. 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.

  9. Multichannel Analysis of Surface Waves and Down-Hole Tests in the Archeological "Palatine Hill" Area (Rome, Italy): Evaluation and Influence of 2D Effects on the Shear Wave Velocity

    NASA Astrophysics Data System (ADS)

    Di Fiore, V.; Cavuoto, G.; Tarallo, D.; Punzo, M.; Evangelista, L.

    2016-05-01

    A joint analysis of down-hole (DH) and multichannel analysis of surface waves (MASW) measurements offers a complete evaluation of shear wave velocity profiles, especially for sites where a strong lateral variability is expected, such as archeological sites. In this complex stratigraphic setting, the high "subsoil anisotropy" (i.e., sharp lithological changes due to the presence of anthropogenic backfill deposits and/or buried man-made structures) implies a different role for DH and MASW tests. This paper discusses some results of a broad experimental program conducted on the Palatine Hill, one of the most ancient areas of the city of Rome (Italy). The experiments were part of a project on seismic microzoning and consisted of 20 MASW and 11 DH tests. The main objective of this study was to examine the difficulties related to the interpretation of the DH and MASW tests and the reliability limits inherent in the application of the noninvasive method in complex stratigraphic settings. As is well known, DH tests provide good determinations of shear wave velocities (Vs) for different lithologies and man-made materials, whereas MASW tests provide average values for the subsoil volume investigated. The data obtained from each method with blind tests were compared and were correlated to site-specific subsurface conditions, including lateral variability. Differences between punctual (DH) and global (MASW) Vs measurements are discussed, quantifying the errors by synthetic comparison and by site response analyses. This study demonstrates that, for archeological sites, VS profiles obtained from the DH and MASW methods differ by more than 15 %. However, the local site effect showed comparable results in terms of natural frequencies, whereas the resolution of the inverted shear wave velocity was influenced by the fundamental mode of propagation.

  10. 2D materials for nanophotonic devices

    NASA Astrophysics Data System (ADS)

    Xu, Renjing; Yang, Jiong; Zhang, Shuang; Pei, Jiajie; Lu, Yuerui

    2015-12-01

    Two-dimensional (2D) materials have become very important building blocks for electronic, photonic, and phononic devices. The 2D material family has four key members, including the metallic graphene, transition metal dichalcogenide (TMD) layered semiconductors, semiconducting black phosphorous, and the insulating h-BN. Owing to the strong quantum confinements and defect-free surfaces, these atomically thin layers have offered us perfect platforms to investigate the interactions among photons, electrons and phonons. The unique interactions in these 2D materials are very important for both scientific research and application engineering. In this talk, I would like to briefly summarize and highlight the key findings, opportunities and challenges in this field. Next, I will introduce/highlight our recent achievements. We demonstrated atomically thin micro-lens and gratings using 2D MoS2, which is the thinnest optical component around the world. These devices are based on our discovery that the elastic light-matter interactions in highindex 2D materials is very strong. Also, I would like to introduce a new two-dimensional material phosphorene. Phosphorene has strongly anisotropic optical response, which creates 1D excitons in a 2D system. The strong confinement in phosphorene also enables the ultra-high trion (charged exciton) binding energies, which have been successfully measured in our experiments. Finally, I will briefly talk about the potential applications of 2D materials in energy harvesting.

  11. Inertial solvation in femtosecond 2D spectra

    NASA Astrophysics Data System (ADS)

    Hybl, John; Albrecht Ferro, Allison; Farrow, Darcie; Jonas, David

    2001-03-01

    We have used 2D Fourier transform spectroscopy to investigate polar solvation. 2D spectroscopy can reveal molecular lineshapes beneath ensemble averaged spectra and freeze molecular motions to give an undistorted picture of the microscopic dynamics of polar solvation. The transition from "inhomogeneous" to "homogeneous" 2D spectra is governed by both vibrational relaxation and solvent motion. Therefore, the time dependence of the 2D spectrum directly reflects the total response of the solvent-solute system. IR144, a cyanine dye with a dipole moment change upon electronic excitation, was used to probe inertial solvation in methanol and propylene carbonate. Since the static Stokes' shift of IR144 in each of these solvents is similar, differences in the 2D spectra result from solvation dynamics. Initial results indicate that the larger propylene carbonate responds more slowly than methanol, but appear to be inconsistent with rotational estimates of the inertial response. To disentangle intra-molecular vibrations from solvent motion, the 2D spectra of IR144 will be compared to the time-dependent 2D spectra of the structurally related nonpolar cyanine dye HDITCP.

  12. [A new 2D and 3D imaging approach to musculoskeletal physiology and pathology with low-dose radiation and the standing position: the EOS system].

    PubMed

    Dubousset, Jean; Charpak, Georges; Dorion, Irène; Skalli, Wafa; Lavaste, François; Deguise, Jacques; Kalifa, Gabriel; Ferey, Solène

    2005-02-01

    Close collaboration between multidisciplinary specialists (physicists, biomecanical engineers, medical radiologists and pediatric orthopedic surgeons) has led to the development of a new low-dose radiation device named EOS. EOS has three main advantages: The use of a gaseous X-ray detector, invented by Georges Charpak (Nobel Prizewinner 1992), the dose necessary to obtain a 2D image of the skeletal system has been reduced by 8 to 10 times, while that required to obtain a 3D reconstruction from CT slices has fallen by a factor of 800 to 1000. The accuracy of the 3D reconstruction obtained with EOS is as good as that obtained with CT. The patient is examined in the standing (or seated) position, and is scanned simultaneously from head to feet, both frontally and laterally. This is a major advantage over conventional CT which requires the patient to be placed horizontally. -The 3D reconstructions of each element of the osteo-articular system are as precise as those obtained by conventional CT. EOS is also rapid, taking only 15 to 30 minutes to image the entire spine. PMID:16114859

  13. Theory and realization of a 2D high resolution and high sensitivity SPECT system with an angle-encoding attenuator pattern

    NASA Astrophysics Data System (ADS)

    Feng, Tao; Wang, Jizhe; Tsui, Benjamin M. W.

    2016-04-01

    The camera of the conventional SPECT system requires a collimator to allow incoming photons from a specific range of incident angle to reach the detector. It is the major factor that determines the spatial resolution of the camera. Moreover, it also greatly reduces the number of detected photons and hence increases statistical fluctuations in the acquired image data. The goal of this paper is to propose a theory and design for a novel high resolution and high sensitivity SPECT system without conventional collimators. The key is to resolve the incident photons from all directional angles and detected by every detector bin. Special ‘attenuators’ were designed to ‘encode’ the incoming photons from different directions similar to coded aperture to form projection data for image reconstruction. Each encoded angular pattern of detected photons was recorded as one measurement. Different angular patterns were achieved by changing the configurations of the attenuators so that angular pattern of different measurements or measurement matrix (MM) is invertible, which guarantee a unique reconstructed image. In simulation, the attenuators were fitted on a virtual full-ring gamma camera, as an alternative to the collimators in conventional SPECT systems. To evaluate the performance of the new SPECT system, analytical simulated projection data in 2D scenario were generated from the XCAT phantom. Noisy simulation using 100 noise realizations suggests that the new attenuator design provides much improved image quality in terms of contrast-noise trade-offs (~30% improvement). The results suggest that the new design of using attenuators to replace collimator is feasible and could potentially improve sensitivity without sacrificing resolution in today’s SPECT systems.

  14. Theory and realization of a 2D high resolution and high sensitivity SPECT system with an angle-encoding attenuator pattern.

    PubMed

    Feng, Tao; Wang, Jizhe; Tsui, Benjamin M W

    2016-04-01

    The camera of the conventional SPECT system requires a collimator to allow incoming photons from a specific range of incident angle to reach the detector. It is the major factor that determines the spatial resolution of the camera. Moreover, it also greatly reduces the number of detected photons and hence increases statistical fluctuations in the acquired image data. The goal of this paper is to propose a theory and design for a novel high resolution and high sensitivity SPECT system without conventional collimators. The key is to resolve the incident photons from all directional angles and detected by every detector bin. Special 'attenuators' were designed to 'encode' the incoming photons from different directions similar to coded aperture to form projection data for image reconstruction. Each encoded angular pattern of detected photons was recorded as one measurement. Different angular patterns were achieved by changing the configurations of the attenuators so that angular pattern of different measurements or measurement matrix (MM) is invertible, which guarantee a unique reconstructed image. In simulation, the attenuators were fitted on a virtual full-ring gamma camera, as an alternative to the collimators in conventional SPECT systems. To evaluate the performance of the new SPECT system, analytical simulated projection data in 2D scenario were generated from the XCAT phantom. Noisy simulation using 100 noise realizations suggests that the new attenuator design provides much improved image quality in terms of contrast-noise trade-offs (~30% improvement). The results suggest that the new design of using attenuators to replace collimator is feasible and could potentially improve sensitivity without sacrificing resolution in today's SPECT systems. PMID:26976649

  15. High divergent 2D grating

    NASA Astrophysics Data System (ADS)

    Wang, Jin; Ma, Jianyong; Zhou, Changhe

    2014-11-01

    A 3×3 high divergent 2D-grating with period of 3.842μm 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.

  16. High-energy signatures of binary systems of supermassive black holes

    NASA Astrophysics Data System (ADS)

    Romero, G. E.; Vila, G. S.; Pérez, D.

    2016-04-01

    Context. Binary systems of supermassive black holes are expected to be strong sources of long gravitational waves prior to merging. These systems are good candidates to be observed with forthcoming space-borne detectors. Only a few of these systems, however, have been firmly identified to date. Aims: We aim at providing a criterion for the identification of some supermassive black hole binaries based on the characteristics of the high-energy emission of a putative relativistic jet launched from the most massive of the two black holes. Methods: We study supermassive black hole binaries where the less massive black hole has carved an annular gap in the circumbinary disk, but nevertheless there is a steady mass flow across its orbit. Such a perturbed disk is hotter and more luminous than a standard thin disk in some regions. Assuming that the jet contains relativistic electrons, we calculate its broadband spectral energy distribution focusing on the inverse Compton up-scattering of the disk photons. We also compute the opacity to the gamma rays produced in the jet by photon annihilation with the disk radiation and take into account the effects of the anisotropy of the target photon field as seen from the jet. Results: We find that the excess of low-energy photons radiated by the perturbed disk causes an increment in the external Compton emission from the jet in the X-ray band, and a deep absorption feature at energies of tens of TeVs for some sets of parameters. According to our results, observations with Cherenkov telescopes might help in the identification of supermassive black hole binaries, especially those black hole binaries that host primaries from tens to hundreds of million of solar masses.

  17. NUBOW-2D Inelastic

    2002-01-31

    This program solves the two-dimensional mechanical equilbrium configuration of a core restraint system, which is subjected to radial temperature and flux gradients, on a time increment basis. At each time increment, the code calculates the irradiation creep and swelling strains for each duct from user-specified creep and swelling correlations. Using the calculated thermal bowing, inelastic bowing and the duct dilation, the corresponding equilibrium forces, beam deflections, total beam displacements, and structural reactivity changes are calculated.

  18. Brittle damage models in DYNA2D

    SciTech Connect

    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.

  19. A System for True and False Memory Prediction Based on 2D and 3D Educational Contents and EEG Brain Signals.

    PubMed

    Bamatraf, Saeed; Hussain, Muhammad; Aboalsamh, Hatim; Qazi, Emad-Ul-Haq; Malik, Amir Saeed; Amin, Hafeez Ullah; Mathkour, Hassan; Muhammad, Ghulam; Imran, Hafiz Muhammad

    2016-01-01

    We studied the impact of 2D and 3D educational contents on learning and memory recall using electroencephalography (EEG) brain signals. For this purpose, we adopted a classification approach that predicts true and false memories in case of both short term memory (STM) and long term memory (LTM) and helps to decide whether there is a difference between the impact of 2D and 3D educational contents. In this approach, EEG brain signals are converted into topomaps and then discriminative features are extracted from them and finally support vector machine (SVM) which is employed to predict brain states. For data collection, half of sixty-eight healthy individuals watched the learning material in 2D format whereas the rest watched the same material in 3D format. After learning task, memory recall tasks were performed after 30 minutes (STM) and two months (LTM), and EEG signals were recorded. In case of STM, 97.5% prediction accuracy was achieved for 3D and 96.6% for 2D and, in case of LTM, it was 100% for both 2D and 3D. The statistical analysis of the results suggested that for learning and memory recall both 2D and 3D materials do not have much difference in case of STM and LTM. PMID:26819593

  20. A System for True and False Memory Prediction Based on 2D and 3D Educational Contents and EEG Brain Signals

    PubMed Central

    2016-01-01

    We studied the impact of 2D and 3D educational contents on learning and memory recall using electroencephalography (EEG) brain signals. For this purpose, we adopted a classification approach that predicts true and false memories in case of both short term memory (STM) and long term memory (LTM) and helps to decide whether there is a difference between the impact of 2D and 3D educational contents. In this approach, EEG brain signals are converted into topomaps and then discriminative features are extracted from them and finally support vector machine (SVM) which is employed to predict brain states. For data collection, half of sixty-eight healthy individuals watched the learning material in 2D format whereas the rest watched the same material in 3D format. After learning task, memory recall tasks were performed after 30 minutes (STM) and two months (LTM), and EEG signals were recorded. In case of STM, 97.5% prediction accuracy was achieved for 3D and 96.6% for 2D and, in case of LTM, it was 100% for both 2D and 3D. The statistical analysis of the results suggested that for learning and memory recall both 2D and 3D materials do not have much difference in case of STM and LTM. PMID:26819593

  1. Investigation of 2D photonic crystal structure based channel drop filter using quad shaped photonic crystal ring resonator for CWDM system

    NASA Astrophysics Data System (ADS)

    Chhipa, Mayur Kumar; Dusad, Lalit Kumar

    2016-05-01

    In this paper, the design & performance of two dimensional (2-D) photonic crystal structure based channel drop filter is investigated using quad shaped photonic crystal ring resonator. In this paper, Photonic Crystal (PhC) based on square lattice periodic arrays of Gallium Indium Phosphide (GaInP) rods in air structure have been investigated using Finite Difference Time Domain (FDTD) method and photonic band gap is being calculated using Plane Wave Expansion (PWE) method. The PhC designs have been optimized for telecommunication wavelength λ= 1571 nm by varying the rods lattice constant. The number of rods in Z and X directions is 21 and 20, with lattice constant 0.540 nm it illustrates that the arrangement of Gallium Indium Phosphide (GaInP) rods in the structure which gives the overall size of the device around 11.4 µm × 10.8 µm. The designed filter gives good dropping efficiency using 3.298, refractive index. The designed structure is useful for CWDM systems. This device may serve as a key component in photonic integrated circuits. The device is ultra compact with the overall size around 123 µm2.

  2. Numerical simulation and wave extraction of binary black hole system

    NASA Astrophysics Data System (ADS)

    Imbiriba, Breno Cesar De Oliveira

    In the first part of this work, we apply finite difference methods, specially mesh refinement techniques, in order to numerically evolve a single black hole, which is represented by the puncture initial data. We use standard second order finite differences, and the second order Iterated Crank-Nicholson integrator. We observe that, in order to obtain a second order accurate evolution we must impose second order accurate interface conditions at the refinement boundaries. We test our evolution with both the geodesic and the 1+log slicing conditions, and observe the expected results. We conclude that our mesh refinement technique generates convergent evolutions, and the puncture method behaves very well with it. The second part of this work deals with a modification of the hybrid "Lazarus" method for wave extraction. This method is divided in three parts: an early evolution, a set of transformations to produce perturbations over a Kerr background from the numerical data, and Teukolsky evolution. By using our evolution code (with mesh refinement) and gauges (1+log, gamma-driver, shifting-shift), we deviate from the original Lazarus approach. We used an independent implementation of the Lazarus transformations, validating the original results, and of the Teukolsky equation. We obtained results similar to the original Lazarus, both on the waveforms as well as on the negative results at later times. For instance, strong pulses that contaminate some gauge transformations, which may be explained in part by the propagating gauge modes of the 1+log slicing. Increasing the accuracy of the initial black hole evolution we seem to obtain better final results for the Kerr test case. Because of the gauge problems, we develop an approximated embedding method which approximates location of the numerical slice into the Kerr spacetime. This method is much less sensitive to the gauge perturbations. Given the difficulties of the Lazarus procedure, we decide to use the Lazarus method as a

  3. Electron dynamics and valley relaxation in 2D semiconductors

    NASA Astrophysics Data System (ADS)

    Gundogdu, Kenan

    2015-03-01

    Single layer transition metal dichalcogenides are 2D semiconducting systems with unique electronic band structure. Two-valley energy bands along with strong spin-orbital coupling lead to valley dependent career spin polarization, which is the basis for recently proposed valleytronic applications. Since the durations of valley population provide the time window in which valley specific processes take place, it is an essential parameter for developing valleytronic devices. These systems also exhibit unusually strong many body affects, such as strong exciton and trion binding, due to reduced dielectric screening of Coulomb interactions. But there is not much known about the impact of strong many particle correlations on spin and valley polarization dynamics. Here we report direct measurements of ultrafast valley specific relaxation dynamics in single layer MoS2 and WS2. We found that excitonic many body interactions significantly contribute to the relaxation process. Biexciton formation reveals hole valley spin relaxation time. Our results also suggest initial fast intervalley electron scattering and electron spin relaxation leads to loss of electron valley polarization, which then facilitates hole valley relaxation via excitonic spin exchange interaction.

  4. INTEGRATED DRILLING SYSTEM USING MUD ACTUATED DOWN HOLE HAMMER AS PRIMARY ENGINE

    SciTech Connect

    John V. Fernandez; David S. Pixton

    2005-12-01

    A history and project summary of the development of an integrated drilling system using a mud-actuated down-hole hammer as its primary engine are given. The summary includes laboratory test results, including atmospheric tests of component parts and simulated borehole tests of the hammer system. Several remaining technical hurdles are enumerated. A brief explanation of commercialization potential is included. The primary conclusion for this work is that a mud actuated hammer can yield substantial improvements to drilling rate in overbalanced, hard rock formations. A secondary conclusion is that the down-hole mud actuated hammer can serve to provide other useful down-hole functions including generation of high pressure mud jets, generation of seismic and sonic signals, and generation of diagnostic information based on hammer velocity profiles.

  5. Micro-Hole Multi-Point Punching System Using Punch and Die Made by EDM

    NASA Astrophysics Data System (ADS)

    Broomfield, Mark; Mori, Toshihiko; Mikuriya, Teruaki; Tachibana, Kazushi

    In this research a multi-point micro punch and die system was developed. The process of electric discharge machining (EDM) was used to produce both the punch and die. The punches were machined from a 5 mm diameter tungsten and a 10 mm diameter tool steel round rods by wire electric discharge machining (WEDM), using a 200 µm diameter wire electrode. The die holes were made using the punch as the electrode. The EDM process of the holes was carried out on a newly developed desktop EDM machine. The punch and die placed on a micro-die set and then on a micro press were used to produce micro-holes using an automatic control system developed for this process. Experiments to produce 50 µm to 67 µm square micro-holes on 50 µm thick aluminum, 30 µm thick copper and 20 µm thick stainless steel foils were conducted. The capabilities of multi-point punching using the tungsten punch and a tool steel punch were examined and tungsten was chosen as the material of choice for making the punch tool. A scanning electron microscope confirmed that the holes produced are clean, and the sheared surfaces smooth. The punch tool showed no signs of deformation or cracks even after repeated punching.

  6. Autoradiographic localization of delta opioid receptors within the mesocorticolimbic dopamine system using radioiodinated (2-D-penicillamine, 5-D-penicillamine)enkephalin ( sup 125 I-DPDPE)

    SciTech Connect

    Dilts, R.P.; Kalivas, P.W. )

    1990-01-01

    The enkephalin analog (2-D-penicillamine, 5-D-penicillamine)enkephalin was radioiodinated (125I-DPDPE) and shown to retain a pharmacological selectivity characteristic of the delta opioid receptor in in vitro binding studies. The distributions of 125I-DPDPE binding, using in vitro autoradiographic techniques, were similar to those previously reported for the delta opioid receptor. The nucleus accumbens, striatum, and medial prefrontal cortex contain dense gradients of 125I-DPDPE binding in regions known to receive dopaminergic afferents emanating from the mesencephalic tegmentum. Selective chemical lesions of the ventral tegmental area and substantia nigra were employed to deduce the location of the 125I-DPDPE binding within particular regions of the mesocorticolimbic dopamine system. Unilateral lesions of dopamine perikarya (A9 and A10) within the ventral tegmental area and substantia nigra produced by mesencephalic injection of 6-hydroxydopamine resulted in significant (20-30%) increases in 125I-DPDPE binding contralateral to the lesion within the striatum and nucleus accumbens. Lesions of the perikarya (dopaminergic and nondopaminergic) of the ventral tegmental area, induced by quinolinic acid injections, caused increases of less magnitude within these same nuclei. No significant alterations in 125I-DPDPE binding were observed within the mesencephalon as a result of either treatment. The specificity of the lesions was confirmed by immunocytochemistry for tyrosine hydroxylase. These results suggest that the enkephalins and opioid agonists acting through delta opioid receptors do not directly modulate dopaminergic afferents but do regulate postsynaptic targets of the mesocorticolimbic dopamine system.

  7. Perturbations of the Black Hole-Torus System: Instabilities and QPOs

    NASA Astrophysics Data System (ADS)

    Donmez, Orhan

    2016-07-01

    The existence of the black hole (BH)-torus system has been given a considerable attention to explain the variability of X-ray and Gamma-ray (γ-ray) data. The perturbation of the black hole-torus system creates instabilities and some of these instabilities are responsible for a quasi-periodic oscillation. In this talk, we present the results from numerical simulation of the dynamical instability of a pressure-supported relativistic torus, rotating around the black hole with a constant specific angular momentum on a fixed space-time background, in case of perturbation. The types of instabilities and their amplitudes strongly depend on what kind of perturbation is applied. The types of perturbations can be a blob of hot gas, Bondi-Hoyle accretion from a finite distance, radial and angular velocity perturbations of the stable accreted torus, and non-spherical accretion as a consequence of isotropic fall of the spherical-shell which has finite thickness. We study the effects of perturbations onto the torus-black hole system by solving the hydrodynamical equations and we have found that the torus around the black hole would have an instability, which is called the Papaloizou-Pringle, and a quasi-periodic oscillation only if we choose a suitable perturbations and initial data. It is noted that, while the perturbations, which are called blob of hot gas, radial velocity perturbations and Bondi-Hoyle accretion, create the Papaloizou-Pringle instability, the Papaloizou-Pringle instability is softly developed and removed in a short time scale for spherical shell accretion. Our studies also indicate that QPOs are common phenomena on the disc around the black holes. If the accretion disc or torus has a quasi-periodic behavior, it emits continuous radiation during the oscillation.

  8. The impact of structural deformation in a 2D basin and petroleum system model of the East Coast Basin, New Zealand

    NASA Astrophysics Data System (ADS)

    Burgreen, B.; Graham, S. A.; Meisling, K. E.

    2013-12-01

    The East Coast Basin of New Zealand is a petroliferous forearc basin that has eluded commercial development largely because of challenges related to its complex structural and tectonic history. Basin formation is associated with three tectonic phases: 1) a Cretaceous convergent margin phase, 2) a Late Cretaceous to Paleogene rifting to passive margin phase, and 3) a Neogene to present convergent margin phase. Beginning in Neogene time, the basin underwent multiple stages of structural deformation including low angle thrust faulting, listric normal faulting, and inversion. This complex basin history provides an ideal situation to test the influence of tectonics on petroleum system development. This study focuses on offshore Hawke Bay where a regional 2D seismic line has been interpreted, palinspastically reconstructed, and incorporated into a basin and petroleum system model. In the model, several paleo-heat flow scenarios are developed to represent the tectonic evolution of the basin. Higher heat flow is modeled during the rifting to passive margin phase, and a reduction in heat flow is modeled during the Neogene phase to account for cold slab subduction. Heat flow scenarios are calibrated to temperature, apatite-fission track data, and vitrinite-intertinite reflectance and fluorescence data from the Hawke Bay-1 and Opoutama-1 wells. The palinspastic reconstructions are integrated into the basin and petroleum system model to assess the impact of different styles of deformation. Faults play a key role in the burial history/rate of burial, fluid migration, and pressure compartmentalization. The relative timing of paleo-heat flow and structural events are tested in the model to understand how they enhance and/or negate effects on petroleum generation. For example, models with early Miocene low angle thrusts (i.e. structural thickening) contemporaneous with remnant high heat flow from the passive margin phase create a scenario for mid-Miocene petroleum generation

  9. Global structure of black holes via the dynamical system

    NASA Astrophysics Data System (ADS)

    Ganguly, Apratim; Gannouji, Radouane; Goswami, Rituparno; Ray, Subharthi

    2015-05-01

    We have recast the system of Einstein field equations for locally rotationally symmetric spacetimes into an autonomous system of covariantly defined geometrical variables. The analysis of this autonomous system gives all the important global features of the maximal extension of these spacetimes. We have concluded that the dynamical system analysis can be a powerful mathematical tool for qualitative understanding of the global structure of spacetimes covariantly, without actually solving the field equations.

  10. Development of an instructional expert system for hole drilling processes

    NASA Technical Reports Server (NTRS)

    Al-Mutawa, Souhaila; Srinivas, Vijay; Moon, Young Bai

    1990-01-01

    An expert system which captures the expertise of workshop technicians in the drilling domain was developed. The expert system is aimed at novice technicians who know how to operate the machines but have not acquired the decision making skills that are gained with experience. This paper describes the domain background and the stages of development of the expert system.

  11. A simple estimate of gravitational wave memory in binary black hole systems

    NASA Astrophysics Data System (ADS)

    Garfinkle, David

    2016-09-01

    A simple estimate is given of gravitational wave memory for the inspiral and merger of a binary black hole system. Here the memory is proportional to the total energy radiated and has a simple angular dependence. Estimates of this sort might be helpful as a consistency check for numerical relativity memory waveforms.

  12. Synthesis and characterization of a new metal organic framework structure with a 2D porous system: (H 2NEt 2) 2[Zn 3(BDC) 4]ṡ3DEF

    NASA Astrophysics Data System (ADS)

    Biemmi, Enrica; Bein, Thomas; Stock, Norbert

    2006-03-01

    A new open-framework zinc terephthalate (H 2NEt 2) 2[Zn 3(BDC) 4]ṡ3DEF (BDC = 1,4-benzendicarboxylate, DEF=N,N-diethylformamide) was obtained under slightly acidic condition by reacting 1,4-benzendicarboxylic acid (H 2BDC) with ZnO in a DEF solution. The structure was obtained by single crystal X-ray diffraction and consists of trimetallic zinc building units, that are interconnected by eight BDC units each (crystal data: monoclinic, C2/c, a=3337.24(5), b=983.17(2), c=1819.67(2) pm, β=92.455(1, V=5965.0(2)×10 pm, Z=4, R=0.0395, wR=0.0843 for 4533 reflections I>2σ(I)). Six BDC ions together with the trimetallic zinc units form a two-dimensional (3,6)-net while the other two BDC unit pillar these layers. Thus a three-dimensional anionic framework with a 2D pore system is formed. The pore space is occupied by solvent molecules (DEF) and diethylammonium ions, produced by in situ hydrolysis of DEF. These are interconnected as well as connected to the framework by hydrogen-bonds. The TG investigation in combination with powder X-ray diffraction and vibrational-spectroscopy show a two-step loss of the pore filling molecules as well as one H 2BDC molecule leading to crystalline phases which are stable up to 250 and 400 °C, respectively. In addition, 13C MAS-NMR data of the title compound is presented.

  13. A core hole into the hydrothermal system of the Long Valley caldera

    SciTech Connect

    Wollenberg, H.; White, A.; Flexser, S.; Sorey, M.; Farrar, C.

    1987-03-01

    To investigate the present-day hydrothermal system, the ''Shady Rest'' hole was continuously cored 715m into the southwestern moat of the Long Valley caldera. The hole intersected 100m of glacial till and 300m of postcaldera rhyolite before entering the welded Bishop Tuff and bottoming in that unit. A sharp temperature rise over the upper 350m, and near-isothermal conditions below reflect the presence of approx.200/sup 0/C water moving through open, calcite-lined fractures in silicified Early Rhyolite and Bishop Tuff. The depth to the Bishop is the shallowest encountered in holes in the caldera, and the temperatures measured are among the hottest observed in wells drilled within the caldera.

  14. Opposite charged two-body system of identical counterrotating black holes

    NASA Astrophysics Data System (ADS)

    Cabrera-Munguia, I.; Lämmerzahl, Claus; López, L. A.; Macías, Alfredo

    2013-10-01

    A four-parametric exact solution describing a two-body system of identical Kerr-Newman counterrotating black holes endowed with opposite electric/magnetic charges is presented. The axis conditions are solved in order to really describe two black holes separated by a massless strut. Moreover, the explicit form of the horizon half length parameter σ in terms of physical Komar parameters, i.e., Komar’s mass M, electric charge QE, angular momentum J, and a coordinate distance R is derived. Additionally, magnetic charges QB arise from the rotation of electrically charged black holes. As a consequence, in order to account for the contribution to the mass of the magnetic charge, the usual Smarr mass formula should be generalized, as it is proposed by A. Tomimatsu, Prog. Theor. Phys. 72, 73 (1984).

  15. Hole-cleaning capabilities of an ester-based drilling fluid system

    SciTech Connect

    Kenny, P.; Hemphill, T.

    1996-03-01

    Well 33/9-C02, located in the Statfjord field in the Norwegian sector of the North Sea, held the world record in extended-reach drilling from 1993--95. To successfully drill a well of this type, an efficient drilling fluid is required to suspend the weighting material and provide good carrying capacity. The ester-based mud system used in the 12{1/4}- and 8{1/2}-in. hole sections of this well exhibited excellent hole-cleaning capabilities. This paper describes the fluid`s performance in the field and in the laboratory where the fluid was tested under down-hole conditions. Fluid rheological behavior is described with the more accurate yield-power law. (YPL) (Herschel-Bulkley) model.

  16. A Universal Scaling for the Energetics of Relativistic Jets From Black Hole Systems

    NASA Technical Reports Server (NTRS)

    Nemmen, R. S.; Georganopoulos, M.; Guiriec, S.; Meyer, E. T.; Gehrels, N.; Sambruna, R. M.

    2013-01-01

    Black holes generate collimated, relativistic jets which have been observed in gamma-ray bursts (GRBs), microquasars, and at the center of some galaxies (active galactic nuclei; AGN). How jet physics scales from stellar black holes in GRBs to the supermassive ones in AGNs is still unknown. Here we show that jets produced by AGNs and GRBs exhibit the same correlation between the kinetic power carried by accelerated particles and the gamma-ray luminosity, with AGNs and GRBs lying at the low and high-luminosity ends, respectively, of the correlation. This result implies that the efficiency of energy dissipation in jets produced in black hole systems is similar over 10 orders of magnitude in jet power, establishing a physical analogy between AGN and GRBs.

  17. Application of spectral hole burning to the study of in vitro cellular systems

    SciTech Connect

    Milanovich, Nebojsa

    1999-11-08

    Chapter 1 of this thesis describes the various stages of tumor development and a multitude of diagnostic techniques used to detect cancer. Chapter 2 gives an overview of the aspects of hole burning spectroscopy important for its application to the study of cellular systems. Chapter 3 gives general descriptions of cellular organelles, structures, and physical properties that can serve as possible markers for the differentiation of normal and cancerous cells. Also described in Chapter 3 are the principles of cryobiology important for low temperature spectroscopy of cells, characterization of MCF-10F (normal) and MCF-7 (cancer) cells lines which will serve as model systems, and cellular characteristics of aluminum phthalocyanine tetrasulfonate (APT), which was used as the test probe. Chapters 4 and 5 are previously published papers by the author pertaining to the results obtained from the application of hole burning to the study of cellular systems. Chapter 4 presents the first results obtained by spectral hole burning of cellular systems and Chapter 5 gives results for the differentiation of MCF-10F and MCF-7 cells stained with APT by an external applied electric (Stark) field. A general conclusion is presented in Chapter 6. Appendices A and B provide additional characterization of the cell/probe model systems. Appendix A describes the uptake and subcellular distribution of APT in MCF-10F and MCF-7 cells and Appendix B compares the hole burning characteristics of APT in cells when the cells are in suspension and when they are examined while adhering to a glass coverslip. Appendix C presents preliminary results for a novel probe molecule, referred to as a molecular thumbtack, designed by the authors for use in future hole burning applications to cellular systems.

  18. Methods and apparatus of suppressing tube waves within a bore hole and seismic surveying systems incorporating same

    DOEpatents

    West, Phillip B.; Haefner, Daryl

    2004-08-17

    Methods and apparatus for attenuating waves in a bore hole, and seismic surveying systems incorporating the same. In one embodiment, an attenuating device includes a soft compliant bladder coupled to a pressurized gas source. A pressure regulating system reduces the pressure of the gas from the gas source prior to entering the bladder and operates in conjunction with the hydrostatic pressure of the fluid in a bore hole to maintain the pressure of the bladder at a specified pressure relative to the surrounding bore hole pressure. Once the hydrostatic pressure of the bore hole fluid exceeds that of the gas source, bore hole fluid may be admitted into a vessel of the gas source to further compress and displace the gas contained therein. In another embodiment, a water-reactive material may be used to provide gas to the bladder wherein the amount of gas generated by the water-reactive material may depend on the hydrostatic pressure of the bore hole fluid.

  19. Methods and apparatus of suppressing tube waves within a bore hole and seismic surveying systems incorporating same

    DOEpatents

    West, Phillip B.; Haefner, Daryl

    2005-12-13

    Methods and apparatus for attenuating waves in a bore hole, and seismic surveying systems incorporating the same. In one embodiment, an attenuating device includes a soft compliant bladder coupled to a pressurized gas source. A pressure regulating system reduces the pressure of the gas from the gas source prior to entering the bladder and operates in conjunction with the hydrostatic pressure of the fluid in a bore hole to maintain the pressure of the bladder at a specified pressure relative to the surrounding bore hole pressure. Once the hydrostatic pressure of the bore hole fluid exceeds that of the gas source, bore hole fluid may be admitted into a vessel of the gas source to further compress and displace the gas contained therein. In another embodiment, a water-reactive material may be used to provide gas to the bladder wherein the amount of gas generated by the water-reactive material may depend on the hydrostatic pressure of the bore hole fluid.

  20. Implications of access hole size on tank waste retrieval system design and cost

    SciTech Connect

    Babcock, S.M.; Kwon, D.S.; Burks, B.L.; Stoughton, R.S.; Evans, M.S.

    1994-05-01

    The DOE Environmental Restoration and Waste Management Robotics Technology Development Program has been investigating the application of robotics technology to the retrieval of waste from single-shell storage tanks for several years. The use of a large, ``long-reach`` manipulator to position and orient a variety of tools and other equipment has been recommended. The objective of this study is to determine the appropriate access hole size for the tank waste retrieval system installation. Previous reports on the impact of access hole size on manipulator performance are summarized. In addition, the practical limitation for access hole size based on structural limitations of the waste storage tanks, the state-of-the-art size limitations for the installation of new risers, the radiation safety implications of various access hole sizes, and overall system cost implications are considered. Basic conclusions include: (1) overall cost of remediation will; be dominated by the costs of the balance of plant and time required to perform the task rather than the cost of manipulator hardware or the cost of installing a riser, (2) the most desirable solution from a manipulator controls point of view is to make the manipulator as stiff as possible and have as high as possible a natural frequency, which implies a large access hole diameter, (3) beyond some diameter; simple, uniform cross-section elements become less advantageous from a weight standpoint and alternative structures should be considered, and (4) additional shielding and contamination control measures would be required for larger holes. Parametric studies summarized in this report considered 3,790,000 1 (1,000,000 gal) tanks, while initial applications are likely to be for 2,840,000 1 (750,000 gal) tanks. Therefore, the calculations should be somewhat conservative, recognizing the limitations of the specific conditions considered.

  1. 2D microwave imaging reflectometer electronics

    SciTech Connect

    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.

  2. 2D microwave imaging reflectometer electronics

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  3. 2D microwave imaging reflectometer electronics.

    PubMed

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

    2014-11-01

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

  4. AnisWave 2D

    2004-08-01

    AnisWave2D is a 2D finite-difference code for a simulating seismic wave propagation in fully anisotropic materials. The code is implemented to run in parallel over multiple processors and is fully portable. A mesh refinement algorithm has been utilized to allow the grid-spacing to be tailored to the velocity model, avoiding the over-sampling of high-velocity materials that usually occurs in fixed-grid schemes.

  5. Mechanical properties of 2D and 3D braided textile composites

    NASA Technical Reports Server (NTRS)

    Norman, Timothy L.

    1991-01-01

    The purpose of this research was to determine the mechanical properties of 2D and 3D braided textile composite materials. Specifically, those designed for tension or shear loading were tested under static loading to failure to investigate the effects of braiding. The overall goal of the work was to provide a structural designer with an idea of how textile composites perform under typical loading conditions. From test results for unnotched tension, it was determined that the 2D is stronger, stiffer, and has higher elongation to failure than the 3D. It was also found that the polyetherether ketone (PEEK) resin system was stronger, stiffer, and had higher elongation at failure than the resin transfer molding (RTM) epoxy. Open hole tension tests showed that PEEK resin is more notch sensitive than RTM epoxy. Of greater significance, it was found that the 3D is less notch sensitive than the 2D. Unnotched compression tests indicated, as did the tension tests, that the 2D is stronger, stiffer, and has higher elongation at failure than the RTM epoxy. The most encouraging results were from compression after impact. The 3D braided composite showed a compression after impact failure stress equal to 92 percent of the unimpacted specimen. The 2D braided composite failed at about 67 percent of the unimpacted specimen. Higher damage tolerance is observed in textiles over conventional composite materials. This is observed in the results, especially in the 3D braided materials.

  6. CYP2D6 and CYP2C19 genotypes of patients with terodiline cardiotoxicity identified through the yellow card system

    PubMed Central

    Ford, Gary A; Wood, Susan M; Daly, Ann K

    2000-01-01

    Aims Terodiline has concentration dependent QT prolonging effects and thus the potential for cardiotoxicity. Pharmacogenetic variation in terodiline metabolism could be responsible for cardiotoxicity. We sought to determine whether CYP2D6 (debrisoquine hydroxylase) or CYP2C19 (S-mephenytoin hydroxylase) status is a risk factor for terodiline cardiotoxicity. Methods Using the UK Yellow Card scheme to identify patients, blood samples were obtained from eight patients who survived ventricular tachycardia or torsades de pointes suspected to be due to terodiline, for determination of CYP2D6 and CYP2C19 genotypes. Genotype prevalence was compared with that in published general population groups. Results One patient was a CYP2D6 poor metaboliser (CYP2D6*4 homozygous) and a second was heterozygous for CYP2D6*4, a slightly lower frequency for these genotypes compared with the general population (P = 0.31). In the case of CYP2C19, one patient was a poor metaboliser and four were heterozygous for the variant CYP2C19*2 allele, compared with general population frequencies of 2% and 23%, respectively (P = 0.035). Conclusions These findings suggest that debrisoquine poor metaboliser status is not primarily responsible for terodiline cardiotoxicity. However, possession of the CYP2C19*2 allele appears to contribute to adverse cardiac reactions to terodiline. The present study demonstrates the feasibility of using spontaneous adverse drug reaction reporting schemes to determine the contribution of genotype for metabolizing enzymes to uncommon adverse drug reactions. PMID:10886124

  7. Measuring the spin of black holes in binary systems using gravitational waves.

    PubMed

    Vitale, Salvatore; Lynch, Ryan; Veitch, John; Raymond, Vivien; Sturani, Riccardo

    2014-06-27

    Compact binary coalescences are the most promising sources of gravitational waves (GWs) for ground-based detectors. Binary systems containing one or two spinning black holes are particularly interesting due to spin-orbit (and eventual spin-spin) interactions and the opportunity of measuring spins directly through GW observations. In this Letter, we analyze simulated signals emitted by spinning binaries with several values of masses, spins, orientations, and signal-to-noise ratios, as detected by an advanced LIGO-Virgo network. We find that for moderate or high signal-to-noise ratio the spin magnitudes can be estimated with errors of a few percent (5%-30%) for neutron star-black hole (black hole-black hole) systems. Spins' tilt angle can be estimated with errors of 0.04 rad in the best cases, but typical values will be above 0.1 rad. Errors will be larger for signals barely above the threshold for detection. The difference in the azimuth angles of the spins, which may be used to check if spins are locked into resonant configurations, cannot be constrained. We observe that the best performances are obtained when the line of sight is perpendicular to the system's total angular momentum and that a sudden change of behavior occurs when a system is observed from angles such that the plane of the orbit can be seen both from above and below during the time the signal is in band. This study suggests that direct measurement of black hole spin by means of GWs can be as precise as what can be obtained from x-ray binaries. PMID:25014800

  8. Correlated Electron Phenomena in 2D Materials

    NASA Astrophysics Data System (ADS)

    Lambert, Joseph G.

    In this thesis, I present experimental results on coherent electron phenomena in layered two-dimensional materials: single layer graphene and van der Waals coupled 2D TiSe2. Graphene is a two-dimensional single-atom thick sheet of carbon atoms first derived from bulk graphite by the mechanical exfoliation technique in 2004. Low-energy charge carriers in graphene behave like massless Dirac fermions, and their density can be easily tuned between electron-rich and hole-rich quasiparticles with electrostatic gating techniques. The sharp interfaces between regions of different carrier densities form barriers with selective transmission, making them behave as partially reflecting mirrors. When two of these interfaces are set at a separation distance within the phase coherence length of the carriers, they form an electronic version of a Fabry-Perot cavity. I present measurements and analysis of multiple Fabry-Perot modes in graphene with parallel electrodes spaced a few hundred nanometers apart. Transition metal dichalcogenide (TMD) TiSe2 is part of the family of materials that coined the term "materials beyond graphene". It contains van der Waals coupled trilayer stacks of Se-Ti-Se. Many TMD materials exhibit a host of interesting correlated electronic phases. In particular, TiSe2 exhibits chiral charge density waves (CDW) below TCDW ˜ 200 K. Upon doping with copper, the CDW state gets suppressed with Cu concentration, and CuxTiSe2 becomes superconducting with critical temperature of T c = 4.15 K. There is still much debate over the mechanisms governing the coexistence of the two correlated electronic phases---CDW and superconductivity. I will present some of the first conductance spectroscopy measurements of proximity coupled superconductor-CDW systems. Measurements reveal a proximity-induced critical current at the Nb-TiSe2 interfaces, suggesting pair correlations in the pure TiSe2. The results indicate that superconducting order is present concurrently with CDW in

  9. Engineering the Charge Transfer in all 2D Graphene-Nanoplatelets Heterostructure Photodetectors.

    PubMed

    Robin, A; Lhuillier, E; Xu, X Z; Ithurria, S; Aubin, H; Ouerghi, A; Dubertret, B

    2016-01-01

    Two dimensional layered (i.e. van der Waals) heterostructures open up great prospects, especially in photodetector applications. In this context, the control of the charge transfer between the constituting layers is of crucial importance. Compared to bulk or 0D system, 2D materials are characterized by a large exciton binding energy (0.1-1 eV) which considerably affects the magnitude of the charge transfer. Here we investigate a model system made from colloidal 2D CdSe nanoplatelets and epitaxial graphene in a phototransistor configuration. We demonstrate that using a heterostructured layered material, we can tune the magnitude and the direction (i.e. electron or hole) of the charge transfer. We further evidence that graphene functionalization by nanocrystals only leads to a limited change in the magnitude of the 1/f noise. These results draw some new directions to design van der Waals heterostructures with enhanced optoelectronic properties. PMID:27143413

  10. Engineering the Charge Transfer in all 2D Graphene-Nanoplatelets Heterostructure Photodetectors

    NASA Astrophysics Data System (ADS)

    Robin, A.; Lhuillier, E.; Xu, X. Z.; Ithurria, S.; Aubin, H.; Ouerghi, A.; Dubertret, B.

    2016-05-01

    Two dimensional layered (i.e. van der Waals) heterostructures open up great prospects, especially in photodetector applications. In this context, the control of the charge transfer between the constituting layers is of crucial importance. Compared to bulk or 0D system, 2D materials are characterized by a large exciton binding energy (0.1–1 eV) which considerably affects the magnitude of the charge transfer. Here we investigate a model system made from colloidal 2D CdSe nanoplatelets and epitaxial graphene in a phototransistor configuration. We demonstrate that using a heterostructured layered material, we can tune the magnitude and the direction (i.e. electron or hole) of the charge transfer. We further evidence that graphene functionalization by nanocrystals only leads to a limited change in the magnitude of the 1/f noise. These results draw some new directions to design van der Waals heterostructures with enhanced optoelectronic properties.

  11. 2D electron temperature diagnostic using soft x-ray imaging technique

    SciTech Connect

    Nishimura, K. Sanpei, A. Tanaka, H.; Ishii, G.; Kodera, R.; Ueba, R.; Himura, H.; Masamune, S.; Ohdachi, S.; Mizuguchi, N.

    2014-03-15

    We have developed a two-dimensional (2D) electron temperature (T{sub e}) diagnostic system for thermal structure studies in a low-aspect-ratio reversed field pinch (RFP). The system consists of a soft x-ray (SXR) camera with two pin holes for two-kinds of absorber foils, combined with a high-speed camera. Two SXR images with almost the same viewing area are formed through different absorber foils on a single micro-channel plate (MCP). A 2D T{sub e} image can then be obtained by calculating the intensity ratio for each element of the images. We have succeeded in distinguishing T{sub e} image in quasi-single helicity (QSH) from that in multi-helicity (MH) RFP states, where the former is characterized by concentrated magnetic fluctuation spectrum and the latter, by broad spectrum of edge magnetic fluctuations.

  12. Engineering the Charge Transfer in all 2D Graphene-Nanoplatelets Heterostructure Photodetectors

    PubMed Central

    Robin, A.; Lhuillier, E.; Xu, X. Z.; Ithurria, S.; Aubin, H.; Ouerghi, A.; Dubertret, B.

    2016-01-01

    Two dimensional layered (i.e. van der Waals) heterostructures open up great prospects, especially in photodetector applications. In this context, the control of the charge transfer between the constituting layers is of crucial importance. Compared to bulk or 0D system, 2D materials are characterized by a large exciton binding energy (0.1–1 eV) which considerably affects the magnitude of the charge transfer. Here we investigate a model system made from colloidal 2D CdSe nanoplatelets and epitaxial graphene in a phototransistor configuration. We demonstrate that using a heterostructured layered material, we can tune the magnitude and the direction (i.e. electron or hole) of the charge transfer. We further evidence that graphene functionalization by nanocrystals only leads to a limited change in the magnitude of the 1/f noise. These results draw some new directions to design van der Waals heterostructures with enhanced optoelectronic properties. PMID:27143413

  13. Measurement of 2D birefringence distribution

    NASA Astrophysics Data System (ADS)

    Noguchi, Masato; Ishikawa, Tsuyoshi; Ohno, Masahiro; Tachihara, Satoru

    1992-10-01

    A new measuring method of 2-D birefringence distribution has been developed. It has not been an easy job to get a birefringence distribution in an optical element with conventional ellipsometry because of its lack of scanning means. Finding an analogy between the rotating analyzer method in ellipsometry and the phase-shifting method in recently developed digital interferometry, we have applied the phase-shifting algorithm to ellipsometry, and have developed a new method that makes the measurement of 2-D birefringence distribution easy and possible. The system contains few moving parts, assuring reliability, and measures a large area of a sample at one time, making the measuring time very short.

  14. Pair interaction energy for a 12-electron 2D square Quantum Dot.

    NASA Astrophysics Data System (ADS)

    Nissenbaum, Daniel; Barbiellini, Bernardo; Bansil, Arun

    2004-03-01

    We have investigated a system of 12 electrons enclosed in a 2D square well representing a quantum dot. We employ a Jastrow-type wavefunction with Slater determinants and optimize the Jastrow parameter using the variational Monte Carlo method. We use the Metropolis algorithm to select a large distribution of configuration points and to perform a relatively noiseless calculation of the radial distribution function and to obtain insight into the contrast between the Fermi hole for the same-spin electrons and the Coulomb hole for the opposite-spin electrons. The calculated pair interaction energy provides a handle for constructing a model Hamiltonian useful for the study of spontaneous spin magnetization of the system. Work supported in part by the USDOE.

  15. 2D Raman correlation analysis of formation mechanism of passivating film on overcharged LiCoO2 electrode with additive system

    NASA Astrophysics Data System (ADS)

    Park, Yeonju; Shin, Su Hyun; Lee, Sung Man; Kim, Sung Phil; Choi, Hyun Chul; Jung, Young Mee

    2014-07-01

    The effect of vinylene carbonate (VC) as solid electrolyte interface (SEI)-forming additive on the electrochemical performance of the LiCoO2 cathode was investigated by galvanostatic charge-discharge testing as well as Raman and 2D correlation spectroscopy. It was found that VC-containing electrolyte has a positive effect on capacity fading. An analysis of the 2D Raman correlation spectra suggested that even though the same SEI components (i.e., Co3O4 and Li2O) are produced on the cathode surface, the electrochemical reaction kinetics in the cathode/electrolyte interface differ according to the non-use or use of VC: in the latter case, formation of the SEI components is delayed.

  16. High-efficiency exfoliation of layered materials into 2D nanosheets in switchable CO2/Surfactant/H2O system

    NASA Astrophysics Data System (ADS)

    Wang, Nan; Xu, Qun; Xu, Shanshan; Qi, Yuhang; Chen, Meng; Li, Hongxiang; Han, Buxing

    2015-11-01

    Layered materials present attractive and important properties due to their two-dimensional (2D) structure, allowing potential applications including electronics, optoelectronics, and catalysis. However, fully exploiting the outstanding properties will require a method for their efficient exfoliation. Here we present that a series of layered materials can be successfully exfoliated into single- and few-layer nanosheets using the driving forces coming from the phase inversion, i.e., from micelles to reverse micelles in the emulsion microenvironment built by supercritical carbon dioxide (SC CO2). The effect of variable experimental parameters including CO2 pressure, ethanol/water ratio, and initial concentration of bulk materials on the exfoliation yield have been investigated. Moreover, we demonstrate that the exfoliated 2D nanosheets have their worthwhile applications, for example, graphene can be used to prepare conductive paper, MoS2 can be used as fluorescent label to perform cellular labelling, and BN can effectively reinforce polymers leading to the promising mechanical properties.

  17. Superconductivity of electron-hole pairs in a bilayer graphene system in a quantizing magnetic field

    NASA Astrophysics Data System (ADS)

    Fil', D. V.; Kravchenko, L. Yu.

    2009-08-01

    A state with spontaneous interlayer phase coherence in a bilayer quantum Hall system based on graphene is studied. This state can be regarded as a gas of superfluid electron-hole pairs whose components belong to different layers. A superfluid flow of such pairs is equivalent to two electric supercurrents in the layers. It is shown that in a graphene system a state with interlayer phase coherence arises if a definite unbalance of the filling factors of the Landau levels in neighboring layers is created. The temperature of the transition into a superfluid state, the maximum interlayer distance for which phase coherence is possible, and the critical values of the supercurrent are found. The advantages of using graphene systems instead of GaAs heterostructures to realize bilayer electron-hole superconductivity are discussed.

  18. Performance of a Multispectral Optoacoustic Tomography (MSOT) System equipped with 2D vs. 3D Handheld Probes for Potential Clinical Translation

    PubMed Central

    Neuschmelting, Volker; Burton, Neal C.; Lockau, Hannah; Urich, Alexander; Harmsen, Stefan; Ntziachristos, Vasilis; Kircher, Moritz F.

    2015-01-01

    A handheld approach to optoacoustic imaging is essential for the clinical translation. The first 2- and 3-dimensional handheld multispectral optoacoustic tomography (MSOT) probes featuring real-time unmixing have recently been developed. Imaging performance of both probes was determined in vitro and in a brain melanoma metastasis mouse model in vivo. T1-weighted MR images were acquired for anatomical reference. The limit of detection of melanoma cells in vitro was significantly lower using the 2D than the 3D probe. The signal decrease was more profound in relation to depth with the 3D versus the 2D probe. Both approaches were capable of imaging the melanoma tumors qualitatively at all time points. Quantitatively, the 2D approach enabled closer anatomical resemblance of the tumor compared to the 3D probe, particularly at depths beyond 3 mm. The 3D probe was shown to be superior for rapid 3D imaging and, thus, holds promise for more superficial target structures. PMID:27069872

  19. Generalized gradient approximation for the exchange-correlation hole of a many-electron system

    SciTech Connect

    Perdew, J.P.; Burke, K.; Wang, Y.

    1996-12-01

    We construct a generalized gradient approximation (GGA) for the density {ital n}{sub xc}({ital r},{ital r}+{ital u}) at position {ital r}+{ital u} of the exchange-correlation hole surrounding an electron at {ital r}, or more precisely for its system and spherical average {l_angle}{ital n}{sub xc}({ital u}){r_angle}=(4{pi}){sup {minus}1}{integral}{ital d}{Omega}{sub {ital u}}{ital N}{sup {minus}1}{integral}{ital d}{sup 3}{ital r} {ital n}({ital r}){ital n}{sub xc}({ital r},{ital r}+{ital u}). Starting from the second-order density gradient expansion, which involves the local spin densities {ital n}{sub {up_arrow}}({ital r}),{ital n}{sub {down_arrow}}({ital r}) and their gradients {nabla}{ital n}{sub {up_arrow}}({ital r}),{nabla}{ital n}{sub {down_arrow}}({ital r}), we cut off the spurious large-{ital u} contributions to restore those exact conditions on the hole that the local spin density (LSD) approximation respects. Our GGA hole recovers the Perdew-Wang 1991 and Perdew-Burke-Ernzerhof GGA{close_quote}s for the exchange-correlation energy, which therefore respect the same powerful hole constraints as LSD. When applied to real systems, our hole model provides a more detailed test of these energy functionals, and also predicts the observable electron-electron structure factor. {copyright} {ital 1996 The American Physical Society.}

  20. A single-payer system in Jackson Hole clothing.

    PubMed

    Enthoven, A C; Singer, S J

    1994-01-01

    President Clinton's Health Security Act relies on government regulation, not market forces, to control costs. The act creates an entitlement to comprehensive benefits and places the federal budget at risk for total health care costs in order to achieve universal coverage; it creates a system of new state purchasing monopsonies; and it attempts to control costs with price controls on health plan premiums, set and administered by a National Health Board that would be part of the executive branch, not insulated from political considerations. We believe there is a better way. PMID:8188160

  1. Geothermal pump down-hole energy regeneration system

    DOEpatents

    Matthews, Hugh B.

    1982-01-01

    Geothermal deep well energy extraction apparatus is provided of the general kind in which solute-bearing hot water is pumped to the earth's surface from a subterranean location by utilizing thermal energy extracted from the hot water for operating a turbine motor for driving an electrical power generator at the earth 3 s surface, the solute bearing water being returned into the earth by a reinjection well. Efficiency of operation of the total system is increased by an arrangement of coaxial conduits for greatly reducing the flow of heat from the rising brine into the rising exhaust of the down-well turbine motor.

  2. Ruggedness of 2D code printed on grain tracers for implementing a prospective grain traceability system to the bulk grain delivery system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Food-grade tracers were printed with two-dimensional Data Matrix (DM) barcode so that they could carry simulated identifying information about grain as part of a prospective traceability system. The key factor in evaluating the tracers was their ability to be read with a code scanner after being rem...

  3. Time domain analysis of superradiant instability for the charged stringy black hole-mirror system

    NASA Astrophysics Data System (ADS)

    Li, Ran; Tian, Yu; Zhang, Hongbao; Zhao, Junkun

    2015-11-01

    It has been proved that the charged stringy black holes are stable under the perturbations of massive charged scalar fields. However, superradiant instability can be generated by adding the mirror-like boundary condition to the composed system of charged stringy black hole and scalar field. The unstable boxed quasinormal modes have been calculated by using both analytical and numerical methods. In this paper, we further provide a time domain analysis by performing a long time evolution of charged scalar field configuration in the background of the charged stringy black hole with the mirror-like boundary condition imposed. We have used the ingoing Eddington-Finkelstein coordinates to derive the evolution equation, and adopted Pseudo-spectral method and the forth-order Runge-Kutta method to evolve the scalar field with the initial Gaussian wave packet. It is shown by our numerical scheme that Fourier transforming the evolution data coincides well with the unstable modes computed from frequency domain analysis. The existence of the rapid growth mode makes the charged stringy black hole a good test ground to study the nonlinear development of superradiant instability.

  4. Specialized drilling systems set new world records in high-angle holes

    SciTech Connect

    Gates, R.L.; Schwab, G.A.

    1984-02-01

    Sound well planning and carefully chosen drilling systems have proved successful in completing two high-angle holes through troublesome formations in the Gippsland basin offshore Victoria, Australia. Located about 60 miles (97 km) out in the Bass Strait, Mackerel Wells A-14 and A-16 set new records for being the longest horizontal displacement wells drilled to an angle of up to 72/sup 0/ (1.26 rad) to the vertical. Both wells are producing oil from a previously fault-isolated reservoir southwest of the platform. The use of invert oil emulsion and aluminum drill pipe represented a significant change from normal Bass Strait drilling operations. This, in conjunction with tightly controlled angle buildup and directional control, ensured that the projected well paths were achieved. Completion procedures peculiar to highly deviated holes also were employed to bring the wells on stream successfully. A ''controlled activity'' oil-continuous mud system was chosen to alleviate problems associated with shale hydration and to increase wellbore lubricity. Rig modifications for cuttings disposal were essential before mud systems could be changed over. In combination with aluminum drill pipe for reduced string weight (Well A-16), the oil mud helped minimize torque, drag, and wall-sticking tendencies. With similar drilling systems and well-planned completion techniques, the drilling of high-angle holes will play a vital role in deepwater development.

  5. A massive binary black-hole system in OJ 287 and a test of general relativity.

    PubMed

    Valtonen, M J; Lehto, H J; Nilsson, K; Heidt, J; Takalo, L O; Sillanpää, A; Villforth, C; Kidger, M; Poyner, G; Pursimo, T; Zola, S; Wu, J-H; Zhou, X; Sadakane, K; Drozdz, M; Koziel, D; Marchev, D; Ogloza, W; Porowski, C; Siwak, M; Stachowski, G; Winiarski, M; Hentunen, V-P; Nissinen, M; Liakos, A; Dogru, S

    2008-04-17

    Tests of Einstein's general theory of relativity have mostly been carried out in weak gravitational fields where the space-time curvature effects are first-order deviations from Newton's theory. Binary pulsars provide a means of probing the strong gravitational field around a neutron star, but strong-field effects may be best tested in systems containing black holes. Here we report such a test in a close binary system of two candidate black holes in the quasar OJ 287. This quasar shows quasi-periodic optical outbursts at 12-year intervals, with two outburst peaks per interval. The latest outburst occurred in September 2007, within a day of the time predicted by the binary black-hole model and general relativity. The observations confirm the binary nature of the system and also provide evidence for the loss of orbital energy in agreement (within 10 per cent) with the emission of gravitational waves from the system. In the absence of gravitational wave emission the outburst would have happened 20 days later. PMID:18421348

  6. Magnetic fields, plasmas, and coronal holes: The inner solar system

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.

    1978-01-01

    In situ magnetic field and plasma observations within 1 AU which describe MDH stream flows and Alfvenic fluctuations, the latest theories of those phenomena are discussed. Understanding of streams and fluctuations was enhanced by the acquisition of nearly complete sets of high resolution plasma and magnetic data simultaneously at two or more points by IMPs 6, 7, and 8, Mariner-Venus-Mercury, HELIOS 1, and HELIOS 2. Observations demonstrate that streams can have very thin boundaries in latitude and longitude near the sun. This has necessitated a revision of earlier views of stream dynamics, for it is now clear that magnetic pressure is a major factor in the dynamics of stream in the inner solar system and that nonlinear phenomena are significant much closer to the sun than previously believed. Simultaneous IMP 6, 7, and 8 observations of Alfvenic fluctuations indicate that they are probably not simply transverse Alfven waves and suggest that Alfvenic fluctuations are better described as nonplanar, large-amplitude, general Alfven waves moving through an inhomogeneous and discontinuous medium, and coupled to a compressive mode.

  7. Confronting Numerical Relativity With Nature: A model-independent characterization of binary black-hole systems in LIGO

    NASA Astrophysics Data System (ADS)

    Jani, Karan; Clark, James; Shoemaker, Deirdre; LIGO Scientific Collaboration; Virgo Collaboration

    2016-03-01

    Stellar and Intermediate mass binary black hole systems (10-1000 solar masses) are likely to be among the strongest sources of gravitational wave detection in Advanced LIGO. In this talk we discuss the prospects for the detection and characterization of these extreme astrophysical system using robust, morphology-independent analysis techniques. In particular, we demonstrate how numerical relativity simulations of black hole collisions may be combined with waveform reconstructions to constrain properties of a binary black-hole system using only exact solutions from general relativity and any potential gravitational wave signal in the data.

  8. Stacking up 2D materials

    NASA Astrophysics Data System (ADS)

    Mayor, Louise

    2016-05-01

    Graphene might be the most famous example, but there are other 2D materials and compounds too. Louise Mayor explains how these atomically thin sheets can be layered together to create flexible “van der Waals heterostructures”, which could lead to a range of novel applications.

  9. Histochemical examination of adipose derived stem cells combined with β-TCP for bone defects restoration under systemic administration of 1α,25(OH)2D3.

    PubMed

    Feng, Wei; Lv, Shengyu; Cui, Jian; Han, Xiuchun; Du, Juan; Sun, Jing; Wang, Kefeng; Wang, Zhenming; Lu, Xiong; Guo, Jie; Oda, Kimimitsu; Amizuka, Norio; Xu, Xin; Li, Minqi

    2015-09-01

    The purpose of this study was to evaluate the effects of osteogenic differentiated adipose-derived stem cell (ADSC) loaded beta-tricalcium phosphate (β-TCP) in the restoration of bone defects under intraperitoneal administration of 1α,25-dihydroxyvitamin D3(1α,25(OH)2D3). ADSCs were isolated from the fat tissue of 8 week old Wister rats and co-cultured with β-TCP for 21 days under osteogenic induction. Then the ADSC-β-TCP complexes were implanted into bone defects in the femora of rats. 1α,25(OH)2D3 (VD) or normal saline (NS) was administrated intraperitoneally every other day after the surgery. Femora were harvested at day 7, day 14 and day 28 post-surgery. There were 4 groups for all specimens: β-TCP-NS group; β-TCP-ADSC-NS group; β-TCP-VD group and β-TCP-ADSC-VD group. Alkaline phosphatase (ALP) was up-regulated obviously in ADSC groups compared with non-ADSC groups at day 7, day 14 and day 28, although high expression of runt-related transcription factor 2 (RUNX2) was only seen at day 7. Furthermore, the number of TRAP-positive osteoclasts and the expression of cathepsin K (CK) were significantly decreased in VD groups compared with non-VD groups at day 7 and day 14. As a most significant finding, the β-TCP-ADSC-VD group showed the highest BV/TV ratio compared with the other three groups at day 28. Taken together, ADSC-loaded β-TCP under the administration of 1α,25(OH)2D3 made a promising therapy for bone defects restoration. PMID:26046276

  10. In vitro inhibition of the cytochrome P450 (CYP450) system by the antiplatelet drug ticlopidine: potent effect on CYP2C19 and CYP2D6

    PubMed Central

    Ko, Jae Wook; Desta, Zeruesenay; Soukhova, Nadia V; Tracy, Timothy; Flockhart, David A

    2000-01-01

    Aims To examine the potency of ticlopidine (TCL) as an inhibitor of cytochrome P450s (CYP450s) in vitro using human liver microsomes (HLMs) and recombinant human CYP450s. Methods Isoform-specific substrate probes of CYP1A2, 2C19, 2C9, 2D6, 2E1 and 3A4 were incubated in HLMs or recombinant CYPs with or without TCL. Preliminary data were generated to simulate an appropriate range of substrate and inhibitor concentrations to construct Dixon plots. In order to estimate accurately inhibition constants (Ki values) of TCL and determine the type of inhibition, data from experiments with three different HLMs for each isoform were fitted to relevant nonlinear regression enzyme inhibition models by WinNonlin. Results TCL was a potent, competitive inhibitor of CYP2C19 (Ki = 1.2 ± 0.5 µm) and of CYP2D6 (Ki = 3.4 ± 0.3 µm). These Ki values fell within the therapeutic steady-state plasma concentrations of TCL (1–3 µm). TCL was also a moderate inhibitor of CYP1A2 (Ki = 49 ± 19 µm) and a weak inhibitor of CYP2C9 (Ki > 75 µm), but its effect on the activities of CYP2E1 (Ki = 584 ± 48 µm) and CYP3A (> 1000 µm) was marginal. Conclusions TCL appears to be a broad-spectrum inhibitor of the CYP isoforms, but clinically significant adverse drug interactions are most likely with drugs that are substrates of CYP2C19 or CYP2D6. PMID:10759690

  11. Structural Variations in the Uranyl/4,4'-Biphenyldicarboxylate System. Rare Examples of 2D → 3D Polycatenated Uranyl-Organic Networks.

    PubMed

    Thuéry, Pierre; Harrowfield, Jack

    2015-08-17

    4,4'-Biphenyldicarboxylic acid (H2L) was reacted with uranyl ions under solvo-hydrothermal conditions with variations in the experimental procedure (organic cosolvent, presence of additional 3d-block metal cations, and N-donor species), thus giving six complexes of the fully deprotonated acid that were characterized by their crystal structure and, in most cases, their emission spectrum. The three complexes [UO2(L)(DMA)] (1), [UO2(L)(NMP)] (2), and [UO2(L)(NMP)] (3) include the cosolvent as a coligand, and they crystallize as two-dimensional (2D) assemblies, with different combinations of the chelating and bridging-bidentate carboxylate coordination modes, resulting in two different topologies. Complex 4, [Ni(bipy)3][(UO2)2(L)2(C2O4)]·H2O, includes oxalate coligands generated in situ and contains an anionic planar two-dimensional (2D) assembly with a {6(3)} honeycomb topology. The same hexagonal geometry is found in the homoleptic complexes [Ni(bipy)3][(UO2)2(L)3]·6H2O (5) and [Ni(phen)3][(UO2)2(L)3]·4H2O (6), but the large size of the hexagonal rings in these cases (∼27 Å in the longest dimension) allows 2D → three-dimensional (3D) inclined polycatenation to occur, with the two families of networks either orthogonal in tetragonal complex 5 or at an angle of 73.4° in orthorhombic complex 6. The parallel networks are arranged in closely spaced groups of two, with possible π···π stacking interactions, and as many as four rods from four parallel nets pass through each ring of the inclined family of nets, an unusually high degree of catenation. These are the second cases only of 2D → 3D inclined polycatenation in uranyl-organic species. Emission spectra measured in the solid state show the usual vibronic fine structure, with variations in intensity and positions of maxima that are not simply connected with the number of equatorial donors and the presence of additional metal cations. PMID:26241368

  12. SU-E-J-13: Six Degree of Freedom Image Fusion Accuracy for Cranial Target Localization On the Varian Edge Stereotactic Radiosurgery System: Comparison Between 2D/3D and KV CBCT Image Registration

    SciTech Connect

    Xu, H; Song, K; Chetty, I; Kim, J; Wen, N

    2015-06-15

    Purpose: To determine the 6 degree of freedom systematic deviations between 2D/3D and CBCT image registration with various imaging setups and fusion algorithms on the Varian Edge Linac. Methods: An anthropomorphic head phantom with radio opaque targets embedded was scanned with CT slice thicknesses of 0.8, 1, 2, and 3mm. The 6 DOF systematic errors were assessed by comparing 2D/3D (kV/MV with CT) with 3D/3D (CBCT with CT) image registrations with different offset positions, similarity measures, image filters, and CBCT slice thicknesses (1 and 2 mm). The 2D/3D registration accuracy of 51 fractions for 26 cranial SRS patients was also evaluated by analyzing 2D/3D pre-treatment verification taken after 3D/3D image registrations. Results: The systematic deviations of 2D/3D image registration using kV- kV, MV-kV and MV-MV image pairs were within ±0.3mm and ±0.3° for translations and rotations with 95% confidence interval (CI) for a reference CT with 0.8 mm slice thickness. No significant difference (P>0.05) on target localization was observed between 0.8mm, 1mm, and 2mm CT slice thicknesses with CBCT slice thicknesses of 1mm and 2mm. With 3mm CT slice thickness, both 2D/3D and 3D/3D registrations performed less accurately in longitudinal direction than thinner CT slice thickness (0.60±0.12mm and 0.63±0.07mm off, respectively). Using content filter and using similarity measure of pattern intensity instead of mutual information, improved the 2D/3D registration accuracy significantly (P=0.02 and P=0.01, respectively). For the patient study, means and standard deviations of residual errors were 0.09±0.32mm, −0.22±0.51mm and −0.07±0.32mm in VRT, LNG and LAT directions, respectively, and 0.12°±0.46°, −0.12°±0.39° and 0.06°±0.28° in RTN, PITCH, and ROLL directions, respectively. 95% CI of translational and rotational deviations were comparable to those in phantom study. Conclusion: 2D/3D image registration provided on the Varian Edge radiosurgery, 6 DOF

  13. H I OBSERVATIONS OF THE SUPERMASSIVE BINARY BLACK HOLE SYSTEM IN 0402+379

    SciTech Connect

    Rodriguez, C.; Taylor, G. B.; Pihlstroem, Y. M.; Zavala, R. T.; Peck, A. B.

    2009-05-20

    We have recently discovered a supermassive binary black hole system with a projected separation between the two black holes of 7.3 pc in the radio galaxy 0402+379 (Rodriguez et al. 2006). This is the most compact supermassive binary black hole pair yet imaged by more than two orders of magnitude. We present Global VLBI observations at 1.3464 GHz of this radio galaxy, taken to improve the quality of the H I data. Two absorption lines are found toward the southern jet of the source, one redshifted by 370 {+-} 10 km s{sup -1} and the other blueshifted by 700 {+-} 10 km s{sup -1} with respect to the systemic velocity of the source, which, along with the results obtained for the opacity distribution over the source, suggests the presence of two mass clumps rotating around the central region of the source. We propose a model consisting of a geometrically thick disk, of which we only see a couple of clumps, that reproduces the velocities measured from the H I absorption profiles. These clumps rotate in circular Keplerian orbits around an axis that crosses one of the supermassive black holes of the binary system in 0402+379. We find an upper limit for the inclination angle of the twin jets of the source to the line of sight of {theta} = 66 deg., which, according to the proposed model, implies a lower limit on the central mass of {approx}7 x 10{sup 8} M {sub sun} and a lower limit for the scale height of the thick disk of {approx}12 pc.

  14. 3D face reconstruction from 2D pictures: first results of a web-based computer aided system for aesthetic procedures.

    PubMed

    Oliveira-Santos, Thiago; Baumberger, Christian; Constantinescu, Mihai; Olariu, Radu; Nolte, Lutz-Peter; Alaraibi, Salman; Reyes, Mauricio

    2013-05-01

    The human face is a vital component of our identity and many people undergo medical aesthetics procedures in order to achieve an ideal or desired look. However, communication between physician and patient is fundamental to understand the patient's wishes and to achieve the desired results. To date, most plastic surgeons rely on either "free hand" 2D drawings on picture printouts or computerized picture morphing. Alternatively, hardware dependent solutions allow facial shapes to be created and planned in 3D, but they are usually expensive or complex to handle. To offer a simple and hardware independent solution, we propose a web-based application that uses 3 standard 2D pictures to create a 3D representation of the patient's face on which facial aesthetic procedures such as filling, skin clearing or rejuvenation, and rhinoplasty are planned in 3D. The proposed application couples a set of well-established methods together in a novel manner to optimize 3D reconstructions for clinical use. Face reconstructions performed with the application were evaluated by two plastic surgeons and also compared to ground truth data. Results showed the application can provide accurate 3D face representations to be used in clinics (within an average of 2 mm error) in less than 5 min. PMID:23319167

  15. High-efficiency exfoliation of layered materials into 2D nanosheets in switchable CO2/Surfactant/H2O system

    PubMed Central

    Wang, Nan; Xu, Qun; Xu, Shanshan; Qi, Yuhang; Chen, Meng; Li, Hongxiang; Han, Buxing

    2015-01-01

    Layered materials present attractive and important properties due to their two-dimensional (2D) structure, allowing potential applications including electronics, optoelectronics, and catalysis. However, fully exploiting the outstanding properties will require a method for their efficient exfoliation. Here we present that a series of layered materials can be successfully exfoliated into single- and few-layer nanosheets using the driving forces coming from the phase inversion, i.e., from micelles to reverse micelles in the emulsion microenvironment built by supercritical carbon dioxide (SC CO2). The effect of variable experimental parameters including CO2 pressure, ethanol/water ratio, and initial concentration of bulk materials on the exfoliation yield have been investigated. Moreover, we demonstrate that the exfoliated 2D nanosheets have their worthwhile applications, for example, graphene can be used to prepare conductive paper, MoS2 can be used as fluorescent label to perform cellular labelling, and BN can effectively reinforce polymers leading to the promising mechanical properties. PMID:26568039

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

    SciTech Connect

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

    2006-11-01

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

  17. UNIVERSAL BEHAVIOR OF X-RAY FLARES FROM BLACK HOLE SYSTEMS

    SciTech Connect

    Wang, F. Y.; Dai, Z. G.; Yi, S. X.; Xi, S. Q. E-mail: dzg@nju.edu.cn

    2015-01-01

    X-ray flares have been discovered in black hole systems such as gamma-ray bursts, the tidal disruption event Swift J1644+57, the supermassive black hole Sagittarius A* at the center of our Galaxy, and some active galactic nuclei. Occurrences of X-ray flares are always accompanied by relativistic jets. However, it is still unknown whether or not there is a physical analogy among such X-ray flares produced in black hole systems spanning nine orders of magnitude in mass. Here, we report observed data of X-ray flares and show that they have three statistical properties similar to solar flares, including power-law distributions of their energies, durations, and waiting times, which can be explained by a fractal-diffusive, self-organized criticality model. These statistical similarities, together with the fact that solar flares are triggered by a magnetic reconnection process, suggest that all of the X-ray flares are consistent with magnetic reconnection events, implying that their concomitant relativistic jets may be magnetically dominated.

  18. Universal Behavior of X-Ray Flares from Black Hole Systems

    NASA Astrophysics Data System (ADS)

    Wang, F. Y.; Dai, Z. G.; Yi, S. X.; Xi, S. Q.

    2015-01-01

    X-ray flares have been discovered in black hole systems such as gamma-ray bursts, the tidal disruption event Swift J1644+57, the supermassive black hole Sagittarius A* at the center of our Galaxy, and some active galactic nuclei. Occurrences of X-ray flares are always accompanied by relativistic jets. However, it is still unknown whether or not there is a physical analogy among such X-ray flares produced in black hole systems spanning nine orders of magnitude in mass. Here, we report observed data of X-ray flares and show that they have three statistical properties similar to solar flares, including power-law distributions of their energies, durations, and waiting times, which can be explained by a fractal-diffusive, self-organized criticality model. These statistical similarities, together with the fact that solar flares are triggered by a magnetic reconnection process, suggest that all of the X-ray flares are consistent with magnetic reconnection events, implying that their concomitant relativistic jets may be magnetically dominated.

  19. Gravitational waves from the Papaloizou-Pringle instability in black-hole-torus systems.

    PubMed

    Kiuchi, Kenta; Shibata, Masaru; Montero, Pedro J; Font, José A

    2011-06-24

    Black hole (BH)-torus systems are promising candidates for the central engine of γ-ray bursts (GRBs), and also possible outcomes of the collapse of supermassive stars to supermassive black holes (SMBHs). By three-dimensional general relativistic numerical simulations, we show that an m = 1 nonaxisymmetric instability grows for a wide range of self-gravitating tori orbiting BHs. The resulting nonaxisymmetric structure persists for a time scale much longer than the dynamical one, becoming a strong emitter of large amplitude, quasiperiodic gravitational waves. Our results indicate that both, the central engine of GRBs and newly formed SMBHs, can be strong gravitational wave sources observable by forthcoming ground-based and spacecraft detectors. PMID:21770625

  20. Electromagnetic properties of a double-layer graphene system with electron-hole pairing

    NASA Astrophysics Data System (ADS)

    Germash, K. V.; Fil, D. V.

    2016-05-01

    We study electromagnetic properties of a double-layer graphene system in which electrons from one layer are coupled with holes from the other layer. The gauge invariant linear response functions are obtained. The frequency dependences of the transmission, reflection, and absorption coefficients are computed. We predict a peak in the reflection and absorption at the frequency equal to the gap in the quasiparticle spectrum. It is shown that the electron-hole pairing results in an essential modification of the spectrum of surface TM plasmons. We find that the optical TM mode splits into a low frequency undamped branch and a high frequency damped branch. At zero temperature the lower branch disappears. It is established that the pairing does not influence the acoustic TM mode. It is also shown that the pairing opens the frequency window in the subgap range for the surface TE wave.

  1. Spontaneous Exciton Condensate in Transition Metal Dichalcogenides electron-hole bilayer System

    NASA Astrophysics Data System (ADS)

    Debnath, Bishwajit; Barlas, Yafis; Wickramaratne, Darshana; Neupane, Mahesh; Lake, Roger

    Spontaneous Bose-Einstein Exciton condensation (BEC) in spatially separated graphene layers has received intense theoretical and experimental attention, due to its promise for low-dissipation electronic devices. We have investigated BN-separated monolayers of transition metal dichalcogenides (TMDs) to explore the possibility of achieving exciton superfluidity in this class of 2D materials. The top and bottom monolayers can consist of either same TMD (homo-bilayer) or a combination of different TMDs (hetero-bilayer). The particle density in each monolayer is tuned by independent gate biasing. In TMDs, the almost equivalent particle-hole symmetry is an assisting factor towards achieving condensation. The calculated exciton binding energies are found to be as large as 50 - 250 meV, which is a result of the large effective masses in the TMDs. For BN thicknesses of around 3nm, the interaction strength is large and no longer in the weak coupling regime. Therefore, to calculate the excitonic gap, we use a modified Eliashberg formalism in which the phonon-mediated interaction is replaced with the inter-layer screened coulomb interaction between TMD bilayers. This work was supported in part by FAME, one of six centers of STARnet, a Semiconductor Research Corporation program sponsored by MARCO and DARPA and NSF EFRI-2DARE 143395.

  2. MOSS2D V1

    2001-01-31

    This software reduces the data from two-dimensional kSA MOS program, k-Space Associates, Ann Arbor, MI. Initial MOS data is recorded without headers in 38 columns, with one row of data per acquisition per lase beam tracked. The final MOSS 2d data file is reduced, graphed, and saved in a tab-delimited column format with headers that can be plotted in any graphing software.

  3. F-18 SRA closeup of nose cap showing new flush air data system sensor holes

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The small numbers on the nose of this F-18 aircraft at NASA's Dryden Flight Research Center, Edwards, California, show the locations of 11 tiny holes which are an integral part of a new air data system installed on the aircraft. The Real-Time Flush Air Data Sensing system measures the speed and direction of the airflow past the aircraft and its altitude, similar to standard air data systems. It incorporates flush-mounted pressure taps, miniature transducers and an advanced research computer to give pilots more accurate information than standard systems employing external probes can provide. Developed by Dryden researchers in cooperation with Honeywell's Research and Technology Center, Minneapolis, Minnesota, the system was flight tested on Dryden's Systems Research Aircraft (SRA) last year, and is now being used as a precise reference for other air data systems currently being evaluated on the modified F-18.

  4. The Lagrange Points in a Binary Black Hole System: Applications to Electromagnetic Signatures

    NASA Technical Reports Server (NTRS)

    Schnittman, Jeremy

    2010-01-01

    We study the stability and evolution of the Lagrange points L_4 and L-5 in a black hole (BH) binary system, including gravitational radiation. We find that gas and stars can be shepherded in with the BH system until the final moments before merger, providing the fuel for a bright electromagnetic counterpart to a gravitational wave signal. Other astrophysical signatures include the ejection of hyper-velocity stars, gravitational collapse of globular clusters, and the periodic shift of narrow emission lines in AGN.

  5. Investigation of coat-develop track system for placement error of contact hole shrink process

    NASA Astrophysics Data System (ADS)

    Harumoto, Masahiko; Stokes, Harold; Tanaka, Yuji; Kaneyama, Koji; Pieczulewski, Charles; Asai, Masaya; Servin, Isabelle; Argoud, Maxime; Gharbi, Ahmed; Lapeyre, Celine; Tiron, Raluca; Monget, Cedric

    2016-04-01

    Directed Self-Assembly (DSA) is a well-known candidate for next generation sub-15nm half-pitch lithography. [1-2] DSA processes on 300mm wafers have been demonstrated for several years, and have given a strong impression due to finer pattern results. [3-4] On t he other hand, specific issues with DSA processes have begun to be clear as a result of these recent challenges. [5-6] Pattern placement error, which means the pattern shift after DSA fabrication, is recognized as one of these typical issues. Coat-Develop Track systems contribute to the DSA pattern fabrication and also influence the DSA pattern performance.[4] In this study, the placement error was investigated using a simple contact-hole pattern and subsequent contact-hole shrink process implemented on the SOKUDO DUO track. Thus, we will show the placement error of contact-hole shrink using a DSA process and discuss the difference between DSA and other shrink methods.

  6. Domain-wall melting in ultracold-boson systems with hole and spin-flip defects

    NASA Astrophysics Data System (ADS)

    Halimeh, Jad C.; Wöllert, Anton; McCulloch, Ian; Schollwöck, Ulrich; Barthel, Thomas

    2014-06-01

    Quantum magnetism is a fundamental phenomenon of nature. As of late, it has garnered a lot of interest because experiments with ultracold atomic gases in optical lattices could be used as a simulator for phenomena of magnetic systems. A paradigmatic example is the time evolution of a domain-wall state of a spin-1/2 Heisenberg chain, the so-called domain-wall melting. The model can be implemented by having two species of bosonic atoms with unity filling and strong on-site repulsion U in an optical lattice. In this paper, we study the domain-wall melting in such a setup on the basis of the time-dependent density matrix renormalization group (tDMRG). We are particularly interested in the effects of defects that originate from an imperfect preparation of the initial state. Typical defects are holes (empty sites) and flipped spins. We show that the dominating effects of holes on observables like the spatially resolved magnetization can be taken account of by a linear combination of spatially shifted observables from the clean case. For sufficiently large U, further effects due to holes become negligible. In contrast, the effects of spin flips are more severe as their dynamics occur on the same time scale as that of the domain-wall melting itself. It is hence advisable to avoid preparation schemes that are based on spin flips.

  7. REVIEWS OF TOPICAL PROBLEMS: Masses of black holes in binary stellar systems

    NASA Astrophysics Data System (ADS)

    Cherepashchuk, Anatolii M.

    1996-08-01

    Mass determination methods and their results for ten black holes in X-ray binary systems are summarised. A unified interpretation of the radial velocity and optical light curves allows one to reliably justify the close binary system model and to prove the correctness of determination of the optical star mass function fv(m).The orbit plane inclination i can be estimated from an analysis of optical light curve of the system, which is due mainly to the ellipsoidal shape of the optical star (the so-called ellipticity effect). The component mass ratio q = mx/mv is obtained from information about the distance to the binary system as well as from data about rotational broadening of absorption lines in the spectrum of the optical star. These data allow one to obtain from the value of fv(m) a reliable value of the black hole mass mx or its low limit, as well as the optical star mass mv. An independent estimate of the optical star mass mv obtained from information about its spectral class and luminosity gives us test results. Additional test comes from information about the absence or presence of X-ray eclipses in the system. Effects of the non-zero dimension of the optical star, its pear-like shape, and X-ray heating on the absorption line profiles and the radial velocity curve are investigated. It is very significant that none of ten known massive (mx > 3M\\odot) X-ray sources considered as black hole candidates is an X-ray pulsar or an X-ray burster of the first kind.

  8. Video camera system for locating bullet holes in targets at a ballistics tunnel

    NASA Technical Reports Server (NTRS)

    Burner, A. W.; Rummler, D. R.; Goad, W. K.

    1990-01-01

    A system consisting of a single charge coupled device (CCD) video camera, computer controlled video digitizer, and software to automate the measurement was developed to measure the location of bullet holes in targets at the International Shooters Development Fund (ISDF)/NASA Ballistics Tunnel. The camera/digitizer system is a crucial component of a highly instrumented indoor 50 meter rifle range which is being constructed to support development of wind resistant, ultra match ammunition. The system was designed to take data rapidly (10 sec between shoots) and automatically with little operator intervention. The system description, measurement concept, and procedure are presented along with laboratory tests of repeatability and bias error. The long term (1 hour) repeatability of the system was found to be 4 microns (one standard deviation) at the target and the bias error was found to be less than 50 microns. An analysis of potential errors and a technique for calibration of the system are presented.

  9. 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.

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

    NASA Astrophysics Data System (ADS)

    Shen, Yanfeng; Giurgiutiu, Victor

    2014-03-01

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

  11. Stochastic Inversion of 2D Magnetotelluric Data

    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

  12. Stochastic Inversion of 2D Magnetotelluric Data

    SciTech Connect

    Chen, Jinsong

    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 is 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

  13. 3He Bilayer Film Adsorbed on Graphite Plated with a Bilayer of 4He: a New Frustrated 2D Magnetic System

    NASA Astrophysics Data System (ADS)

    Neumann, Michael; Nyéki, Ján; Cowan, Brian; Saunders, John

    2006-09-01

    The heat capacity and NMR response of a 3He bilayer adsorbed on graphite plated with a bilayer of 4He have been measured over the temperature range 1-80 mK. We find that the first 3He layer requires the presence of a 3He fluid overlayer before it solidifies. Solidification is completed at a total coverage close to 9.85 nm-2, On further increasing the coverage the heat capacity maximum grows from `antiferromagnetic-like' (AFM-like) to `ferromagnetic-like' (FM-like). On the other hand, when the 3He layer first solidifies, it has a low temperature saturation magnetisation corresponding to a significant fraction of full polarisation, and this increases with increasing coverage. Furthermore the effective exchange constant inferred from the high temperature magnetisation data is always ferromagnetic. The effective exchange constants inferred from the heat capacity and magnetisation are significantly larger than those observed in the second layer of pure 3He films adsorbed on bare graphite. Otherwise there are strong similarities in the coverage dependence of the heat capacity and magnetisation, providing fresh insights into how the magnetic ground state of such 2D magnets evolves as the frustration is tuned with increasing coverage.

  14. A new methodology in fast and accurate matching of the 2D and 3D point clouds extracted by laser scanner systems

    NASA Astrophysics Data System (ADS)

    Torabi, M.; Mousavi G., S. M.; Younesian, D.

    2015-03-01

    Registration of the point clouds is a conventional challenge in computer vision related applications. As an application, matching of train wheel profiles extracted from two viewpoints is studied in this paper. The registration problem is formulated into an optimization problem. An error minimization function for registration of the two partially overlapping point clouds is presented. The error function is defined as the sum of the squared distance between the source points and their corresponding pairs which should be minimized. The corresponding pairs are obtained thorough Iterative Closest Point (ICP) variants. Here, a point-to-plane ICP variant is employed. Principal Component Analysis (PCA) is used to obtain tangent planes. Thus it is shown that minimization of the proposed objective function diminishes point-to-plane ICP variant. We utilized this algorithm to register point clouds of two partially overlapping profiles of wheel train extracted from two viewpoints in 2D. Also, a number of synthetic point clouds and a number of real point clouds in 3D are studied to evaluate the reliability and rate of convergence in our method compared with other registration methods.

  15. 2dF mechanical engineering

    NASA Astrophysics Data System (ADS)

    Smith, Greg; Lankshear, Allan

    1998-07-01

    2dF is a multi-object instrument mounted at prime focus at the AAT capable of spectroscopic analysis of 400 objects in a single 2 degree field. It also prepares a second 2 degree 400 object field while the first field is being observed. At its heart is a high precision robotic positioner that places individual fiber end magnetic buttons on one of two field plates. The button gripper is carried on orthogonal gantries powered by linear synchronous motors and contains a TV camera which precisely locates backlit buttons to allow placement in user defined locations to 10 (mu) accuracy. Fiducial points on both plates can also be observed by the camera to allow repeated checks on positioning accuracy. Field plates rotate to follow apparent sky rotation. The spectrographs both analyze light from the 200 observing fibers each and back- illuminate the 400 fibers being re-positioned during the observing run. The 2dF fiber position and spectrograph system is a large and complex instrument located at the prime focus of the Anglo Australian Telescope. The mechanical design has departed somewhat from the earlier concepts of Gray et al, but still reflects the audacity of those first ideas. The positioner is capable of positioning 400 fibers on a field plate while another 400 fibers on another plate are observing at the focus of the telescope and feeding the twin spectrographs. When first proposed it must have seemed like ingenuity unfettered by caution. Yet now it works, and works wonderfully well. 2dF is a system which functions as the result of the combined and coordinated efforts of the astronomers, the mechanical designers and tradespeople, the electronic designers, the programmers, the support staff at the telescope, and the manufacturing subcontractors. The mechanical design of the 2dF positioner and spectrographs was carried out by the mechanical engineering staff of the AAO and the majority of the manufacture was carried out in the AAO workshops.

  16. Realistic and efficient 2D crack simulation

    NASA Astrophysics Data System (ADS)

    Yadegar, Jacob; Liu, Xiaoqing; Singh, Abhishek

    2010-04-01

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

  17. Impact of short-range scattering on the metallic transport of strongly correlated two-dimensional holes in GaAs quantum wells

    NASA Astrophysics Data System (ADS)

    Goble, Nicholas J.; Watson, John D.; Manfra, Michael J.; Gao, Xuan P. A.

    2014-07-01

    Understanding the nonmonotonic behavior in the temperature dependent resistance R(T) of strongly correlated two-dimensional (2D) carriers in clean semiconductors has been a central issue in the studies of 2D metallic states and metal-insulator transitions. We have studied the transport of high mobility 2D holes in 20-nm-wide GaAs quantum wells with varying short-range disorder strength by changing the Al fraction x in the AlxGa1-xAs barrier. Via varying the short-range interface roughness and alloy scattering, it is observed that increasing x suppresses both the strength and characteristic temperature scale of the 2D metallicity, pointing to the distinct role of short-range vs long-range disorder in the 2D metallic transport in this correlated 2D hole system with interaction parameter rs˜20.

  18. Doppler Imaging of Black Hole SYSTEMS:XTE J1118+480.

    NASA Astrophysics Data System (ADS)

    Callanan, Paul; Perres-Torres, Manuel; Garcia, Michael

    We present time-resolved spectroscopy of the black-hole candidate XTE J1118+480 obtained during its approach to quiescence. Doppler imaging of the intense Hα line shows persistent emission with an origin in the gas stream/hotspot. In addition the Doppler maps show enhanced emission in the +Vx -Vy quadrant clearing incompatible with a stream/hotspot origin. We favour a non-uniform disk intensity distribution due to tidal effects as the origin of this emission. We compare our map with that of XTE J1118+480 in outburst as well as with those of other transient systems in quiescence

  19. Topological Toughening of graphene and other 2D materials

    NASA Astrophysics Data System (ADS)

    Gao, Huajian

    It has been claimed that graphene, with the elastic modulus of 1TPa and theoretical strength as high as 130 GPa, is the strongest material. However, from an engineering point of view, it is the fracture toughness that determines the actual strength of materials, as crack-like flaws (i.e., cracks, holes, notches, corners, etc.) are inevitable in the design, fabrication, and operation of practical devices and systems. Recently, it has been demonstrated that graphene has very low fracture toughness, in fact close to that of ideally brittle solids. These findings have raised sharp questions and are calling for efforts to explore effective methods to toughen graphene. Recently, we have been exploring the potential use of topological effects to enhance the fracture toughness of graphene. For example, it has been shown that a sinusoidal graphene containing periodically distributed disclination quadrupoles can achieve a mode I fracture toughness nearly twice that of pristine graphene. Here we report working progresses on further studies of topological toughening of graphene and other 2D materials. A phase field crystal method is adopted to generate the atomic coordinates of material with specific topological patterns. We then perform molecular dynamics simulations of fracture in the designed samples, and observe a variety of toughening mechanisms, including crack tip blunting, crack trapping, ligament bridging, crack deflection and daughter crack initiation and coalescence.

  20. Analysis of spin precession in binary black hole systems including quadrupole-monopole interaction

    NASA Astrophysics Data System (ADS)

    Racine, Étienne

    2008-08-01

    We analyze in detail the spin precession equations in binary black hole systems, when the tidal torque on a Kerr black hole due to quadrupole-monopole coupling is taken into account. We show that completing the precession equations with this term reveals the existence of a conserved quantity at 2PN order when averaging over orbital motion. This quantity allows one to solve the (orbit-averaged) precession equations exactly in the case of equal masses and arbitrary spins, neglecting radiation reaction. For unequal masses, an exact solution does not exist in closed form, but we are still able to derive accurate approximate analytic solutions. We also show how to incorporate radiation-reaction effects into our analytic solutions adiabatically, and compare the results to solutions obtained numerically. For various configurations of the binary, the relative difference in the accumulated orbital phase computed using our analytic solutions versus a full numerical solution varies from ˜0.3% to ˜1.8% over ˜80 140 orbital cycles accumulated while sweeping over the orbital frequency range ˜20 300Hz. This typically corresponds to a discrepancy of order ˜5 6 radians. While this may not be accurate enough for implementation in LIGO template banks, we still believe that our new solutions are potentially quite useful for comparing numerical relativity simulations of spinning binary black hole systems with post-Newtonian theory. They can also be used to gain more understanding of precession effects, with potential application to the gravitational recoil problem, and to provide semianalytical templates for spinning, precessing binaries.

  1. Fabrication and Characterization of a Single Hole Transistor in p-type GaAs/AlGaAs Heterostructures

    SciTech Connect

    Tracy, Lisa A; Reno, John L.; Hargett, Terry W.

    2015-09-01

    Most spin qubit research to date has focused on manipulating single electron spins in quantum dots. However, hole spins are predicted to have some advantages over electron spins, such as reduced coupling to host semiconductor nuclear spins and the ability to control hole spins electrically using the large spin-orbit interaction. Building on recent advances in fabricating high-mobility 2D hole systems in GaAs/AlGaAs heterostructures at Sandia, we fabricate and characterize single hole transistors in GaAs. We demonstrate p-type double quantum dot devices with few-hole occupation, which could be used to study the physics of individual hole spins and control over coupling between hole spins, looking towards eventual applications in quantum computing. Intentionally left blank

  2. Phosphorene: A New High-Mobility 2D Semiconductor

    NASA Astrophysics Data System (ADS)

    Liu, Han; Neal, Adam; Zhu, Zhen; Tomanek, David; Ye, Peide

    2014-03-01

    The rise of 2D crystals has opened various possibilities for future electrical and optical applications. MoS2 n-type transistors are showing great potential in ultra-scaled and low-power electronics. Here, we introduce phosphorene, a name we coined for 2D few-layer black phosphorus, a new 2D material with layered structure. We perform ab initio band structure calculations and show that the fundamental band gap depends sensitively on the number of layers. We observe transport behavior, which shows a mobility variation in the 2D plane. High on-current of 194 mA/mm, high hole mobility up to 286 cm2/V .s and on/off ratio up to 104 was achieved with phosphorene transistors at room temperature. Schottky barrier height at the metal/phosphorene interface was also measured as a function of temperature. We demonstrate a CMOS inverter with combination to MoS2 NMOS transistors, which shows great potential for semiconducting 2D crystals in future electronic, optoelectronic and flexible electronic devices.

  3. MULTIPLE TIDAL DISRUPTIONS AS AN INDICATOR OF BINARY SUPERMASSIVE BLACK HOLE SYSTEMS

    SciTech Connect

    Wegg, Christopher; Nate Bode, J.

    2011-09-01

    We find that the majority of systems hosting multiple tidal disruptions (TDs) are likely to contain hard binary supermassive black hole (SMBH) systems, and also show that the rates of these repeated events are high enough to be detected by the Large Synoptic Survey Telescope (LSST) over its lifetime. Therefore, these multiple TD events provide a novel method for identifying SMBH binary systems with parsec to subparsec separations. The rates of TDs are investigated using simulations of non-interacting stars initially orbiting a primary SMBH and the potential of the model stellar cusp. The stars are then evolved forward in time and perturbed by a secondary SMBH inspiraling from the edge of the cusp to its stalling radius. We find with conservative magnitude estimates that the next-generation transient survey LSST should detect multiple TDs in approximately three galaxies over five years of observation, though less conservative estimates could increase this rate by an order of magnitude.

  4. Dynamics of an elementary quantum system outside a radiating Schwarzschild black hole

    NASA Astrophysics Data System (ADS)

    Hu, Jiawei; Zhou, Wenting; Yu, Hongwei

    2013-10-01

    We study, in the framework of open quantum systems, the dynamics of a radially polarizable two-level atom in multipolar coupling to fluctuating vacuum electromagnetic fields which is placed at a fixed radial distance outside a radiating Schwarzschild black hole, and we analyze the transition rates between atomic energy levels and the steady state the atom is driven to. We find that the atom always thermalizes toward a steady state at an effective temperature between zero and the Hawking temperature of the black hole. Remarkably, the thermalization temperature depends on the transition frequency of the atom, so that atoms with different transition frequencies essentially thermalize to different temperatures. This counterintuitive behavior is however in close analogy to what happens for a two-level atom in a stationary environment out of thermal equilibrium near a dielectric body of certain geometry and dielectric permittivity. Our results thereby suggest in principle a possible analogue system, using engineered materials with certain desired dielectric properties to verify features of Hawking radiation in tabletop experiments.

  5. F-18 SRA closeup of nose cap showing new flush air data system sensor holes

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Small numbers on the nose cap of this F-18 Systems Research Aircraft at NASA's Dryden Flight Research Center, Edwards, California, show the locations of 11 tiny holes, which are an integral part of a new air data system installed on the aircraft. The Real-Time Flush Air Data Sensing system measures the speed and direction of the airflow past the aircraft and its altitude, similar to standard air data systems. It differs from those systems by incorporating flush-mounted pressure taps, miniature transducers and an advanced research computer to give the pilot more accurate information than systems employing external probes provide. Stephen A. Whitmore of Dryden's Aerodynamics Branch won NASA's Space Act Award for his development of the Real-Time Flush Air Data Sensing system. The award honors projects which are scientifically or technologically significant to the aeronautics and space community. The system was flight tested on the modified F-18 last year, and is now being used as a precise reference system for other air data systems currently being evaluated on the aircraft.

  6. Accuracy and Precision of a Custom Camera-Based System for 2-D and 3-D Motion Tracking during Speech and Nonspeech Motor Tasks

    ERIC Educational Resources Information Center

    Feng, Yongqiang; Max, Ludo

    2014-01-01

    Purpose: Studying normal or disordered motor control requires accurate motion tracking of the effectors (e.g., orofacial structures). The cost of electromagnetic, optoelectronic, and ultrasound systems is prohibitive for many laboratories and limits clinical applications. For external movements (lips, jaw), video-based systems may be a viable…

  7. Interparticle Attraction in 2D Complex Plasmas

    NASA Astrophysics Data System (ADS)

    Kompaneets, Roman; Morfill, Gregor E.; Ivlev, Alexei V.

    2016-03-01

    Complex (dusty) plasmas allow experimental studies of various physical processes occurring in classical liquids and solids by directly observing individual microparticles. A major problem is that the interaction between microparticles is generally not molecularlike. In this Letter, we propose how to achieve a molecularlike interaction potential in laboratory 2D complex plasmas. We argue that this principal aim can be achieved by using relatively small microparticles and properly adjusting discharge parameters. If experimentally confirmed, this will make it possible to employ complex plasmas as a model system with an interaction potential resembling that of conventional liquids.

  8. A scalable 2-D parallel sparse solver

    SciTech Connect

    Kothari, S.C.; Mitra, S.

    1995-12-01

    Scalability beyond a small number of processors, typically 32 or less, is known to be a problem for existing parallel general sparse (PGS) direct solvers. This paper presents a parallel general sparse PGS direct solver for general sparse linear systems on distributed memory machines. The algorithm is based on the well-known sequential sparse algorithm Y12M. To achieve efficient parallelization, a 2-D scattered decomposition of the sparse matrix is used. The proposed algorithm is more scalable than existing parallel sparse direct solvers. Its scalability is evaluated on a 256 processor nCUBE2s machine using Boeing/Harwell benchmark matrices.

  9. 2D potential measurements by applying automatic beam adjustment system to heavy ion beam probe diagnostic on the Large Helical Devicea)

    NASA Astrophysics Data System (ADS)

    Shimizu, A.; Ido, T.; Kurachi, M.; Makino, R.; Nishiura, M.; Kato, S.; Nishizawa, A.; Hamada, Y.

    2014-11-01

    Two-dimensional potential profiles in the Large Helical Device (LHD) were measured with heavy ion beam probe (HIBP). To measure the two-dimensional profile, the probe beam energy has to be changed. However, this task is not easy, because the beam transport line of LHD-HIBP system is very long (˜20 m), and the required beam adjustment consumes much time. To reduce the probe beam energy adjustment time, an automatic beam adjustment system has been developed. Using this system, required time to change the probe beam energy is dramatically reduced, such that two-dimensional potential profiles were able to be successfully measured with HIBP by changing the probe beam energy shot to shot.

  10. 2D potential measurements by applying automatic beam adjustment system to heavy ion beam probe diagnostic on the Large Helical Device

    SciTech Connect

    Shimizu, A. Ido, T.; Kato, S.; Hamada, Y.; Kurachi, M.; Makino, R.; Nishiura, M.; Nishizawa, A.

    2014-11-15

    Two-dimensional potential profiles in the Large Helical Device (LHD) were measured with heavy ion beam probe (HIBP). To measure the two-dimensional profile, the probe beam energy has to be changed. However, this task is not easy, because the beam transport line of LHD-HIBP system is very long (∼20 m), and the required beam adjustment consumes much time. To reduce the probe beam energy adjustment time, an automatic beam adjustment system has been developed. Using this system, required time to change the probe beam energy is dramatically reduced, such that two-dimensional potential profiles were able to be successfully measured with HIBP by changing the probe beam energy shot to shot.

  11. Van der Waals stacked 2D layered materials for optoelectronics

    NASA Astrophysics Data System (ADS)

    Zhang, Wenjing; Wang, Qixing; Chen, Yu; Wang, Zhuo; Wee, Andrew T. S.

    2016-06-01

    The band gaps of many atomically thin 2D layered materials such as graphene, black phosphorus, monolayer semiconducting transition metal dichalcogenides and hBN range from 0 to 6 eV. These isolated atomic planes can be reassembled into hybrid heterostructures made layer by layer in a precisely chosen sequence. Thus, the electronic properties of 2D materials can be engineered by van der Waals stacking, and the interlayer coupling can be tuned, which opens up avenues for creating new material systems with rich functionalities and novel physical properties. Early studies suggest that van der Waals stacked 2D materials work exceptionally well, dramatically enriching the optoelectronics applications of 2D materials. Here we review recent progress in van der Waals stacked 2D materials, and discuss their potential applications in optoelectronics.

  12. Effects of the electron-electron interaction in the spin resonance in 2D systems with Dresselhaus spin-orbit coupling

    SciTech Connect

    Krishtopenko, S. S.

    2015-02-15

    The effect of the electron-electron interaction on the spin-resonance frequency in two-dimensional electron systems with Dresselhaus spin-orbit coupling is investigated. The oscillatory dependence of many-body corrections on the magnetic field is demonstrated. It is shown that the consideration of many-body interaction leads to a decrease or an increase in the spin-resonance frequency, depending on the sign of the g factor. It is found that the term cubic in quasimomentum in Dresselhaus spin-orbit coupling partially decreases exchange corrections to the spin resonance energy in a two-dimensional system.

  13. An innovation approach to exploration and exploitation drilling; The slim-hole high-speed drilling system

    SciTech Connect

    Walker, S.H. ); Millheim, K.K. )

    1990-09-01

    This paper reports how slim-hole continuous-core drilling and on-site near-real-time core analysis offer a new dimension for oil and gas exploration, especially in remote, difficult, and environmentally sensitive areas. Technologies borrowed from the mining and oilfield drilling industries coupled with newly developed technologies were used to create a new drilling and evaluation system designed around continuous coring, slim holes, and inverse logging--i.e., the logging of the actual rock as it is retrieved. This new system could cause a paradigm shift in exploration.

  14. A nonmagnetic impurity in a 2D quantum critical antiferromagnet

    NASA Astrophysics Data System (ADS)

    Troyer, Matthias

    2003-03-01

    We compute the properties of a mobile hole and a static impurity injected into a two-dimensional antiferromagnet or superconductor in the vicinity of a magnetic quantum critical point. A static S=1/2 impurity doped into a quantum-disordered spin gap system induces a local moment with spin S=1/2 and a corresponding Curie-like impurity susceptibility, while the same impurity in a Néel ordered state only gives a finite impurity susceptibility. For the quantum critical system however an interesting field-theoretical prediction has been made that there the impurity spin susceptibility still has a Curie-like divergence, but with a universal effective spin that is neither an integer nor a half-odd integer [1]. In large-scale quantum Monte Carlo (QMC) simulations using the loop algorithm we calculate the impurity susceptibility and find that, unfortunately, this effect is not observable since the renormalization of the effective spin away from S=1/2 is minimal. Other predictions of the field theory, such as a new critical exponent η' describing the time-dependent impurity spin correlations can however be confirmed [2]. Next we compute the spectral function of a hole injected into a 2D antiferromagnet or superconductor in the vicinity of a magnetic quantum critical point [3]. We show that, near van Hove singularities, the problem maps onto that of a static vacancy. This allows the calculation of the spectral function in a QMC simulation without encountering the negative sign problem. We find a vanishing quasiparticle residue at the critical point, a new exponent η_h0.080.04 describing the frequency dependence of the spectral function G_h(ω)(ɛ_0-ω)-1+ηh and discuss possible relevance to photoemission spectra of cuprate superconductors near the antinodal points. ^1 S. Sachdev, C. Buragohain and M. Vojta, Science 286, 2479 (1999). ^2 M. Troyer, in Prog. Theor. Phys. Suppl. 145 (2002); M. Körner and M. Troyer, ibid. ^3 S. Sachdev, M. Troyer, and M. Vojta, Phys. Rev

  15. An application of the tensor virial theorem to hole + vortex + bulge systems

    NASA Astrophysics Data System (ADS)

    Caimmi, R.

    2009-04-01

    The tensor virial theorem for subsystems is formulated for three-component systems and further effort is devoted to a special case where the inner subsystems and the central region of the outer one are homogeneous, the last surrounded by an isothermal homeoid. The virial equations are explicitly written under the additional restrictions: (i) similar and similarly placed inner subsystems, and (ii) spherical outer subsystem. An application is made to hole + vortex + bulge systems, in the limit of flattened inner subsystems, which implies three virial equations in three unknowns. Using the Faber-Jackson relation, R∝σ02, the standard M- σ0 form (M∝σ04) is deduced from qualitative considerations. The projected bulge velocity dispersion to projected vortex velocity ratio, η=(σ)33/{[(v)qq]2+[(σ)qq]2}, as a function of the fractional radius, y=R/R, and the fractional masses, m=M/M and m=M/M, is studied in the range of interest, 0⩽m=M/M⩽5 [Escala, A., 2006. ApJ, 648, L13] and 229⩽m⩽795 [Marconi, A., Hunt, L.H., 2003. ApJ 589, L21], consistent with observations. The related curves appear to be similar to Maxwell velocity distributions, which implies a fixed value of η below the maximum corresponds to two different configurations: a compact bulge on the left of the maximum, and an extended bulge on the right. All curves lie very close one to the other on the left of the maximum, and parallel one to the other on the right. On the other hand, fixed m or m, and y, are found to imply more massive bulges passing from bottom to top along a vertical line on the (Oyη) plane, and vice versa. The model is applied to NGC 4374 and NGC 4486, taking the fractional mass, m, and the fractional radius, y, as unknowns, and the bulge mass is inferred from the knowledge of the hole mass, and compared with results from different methods. In presence of a massive vortex (m=5), the hole mass has to be reduced by a factor 2-3 with respect to the case of a massless vortex, to get

  16. Transport and percolation in a low-density high-mobility two-dimensional hole system.

    PubMed

    Manfra, M J; Hwang, E H; Das Sarma, S; Pfeiffer, L N; West, K W; Sergent, A M

    2007-12-01

    We present a study of the temperature and density dependence of the resistivity of an extremely high quality two-dimensional hole system grown on the (100) surface of GaAs. For high densities in the metallic regime (p > or approximately4x10;{9} cm;{-2}), the nonmonotonic temperature dependence ( approximately 50-300 mK) of the resistivity is consistent with temperature dependent screening of residual impurities. At a fixed temperature of T=50 mK, the conductivity versus density data indicate an inhomogeneity driven percolation-type transition to an insulating state at a critical density of 3.8x10;{9} cm;{-2}. PMID:18233387

  17. Spectral hole burning and flourescence studies of a synthetic chlorophyll dimer, a bacterial antenna system and a bacterial reaction center

    SciTech Connect

    Johnson, S.G.

    1990-06-13

    Hole burning and fluorescence spectroscopy are applied to a synthetic chlorophyll dimer, an antenna system from the bacterium Prosthecochloris aestuarii and a reaction center from the bacterium Rhodobacter sphaeroides. Information concerning the strength of the linear electron-phonon (exciton-phonon) coupling, inhomogeneous broadening, energy transfer times, nature or structure of the excited states (S{sub 1}), the excited state decay times and the vibrational levels of S{sub 1} for these three systems are reported and discussed. A theory for modelling the hole shape and absorption profile for a single transition which is inhomogeneously broadened and coupled to two low frequency modes, with arbitrary coupling strength, is presented and applied to photochemical hole spectra and the absorption profile of the bacterial RC from Rhodobacter sphaeroides. 122 refs., 29 figs.

  18. Composition of an emission line system in black hole host globular cluster RZ2109

    SciTech Connect

    Steele, Matthew M.; Zepf, Stephen E.; Maccarone, Thomas J.; Kundu, Arunav; Rhode, Katherine L.; Salzer, John J.

    2014-04-20

    We present an analysis of optical spectra from the globular cluster RZ2109 in NGC 4472, which hosts the first unambiguous globular cluster black hole. We use these spectra to determine the elemental composition of the emission line system associated with this source, and to constrain the age and metallicity of the host globular cluster. For the emission line system of RZ2109, our analysis indicates the [O III] λ5007 equivalent width is 33.82 ± 0.39 Å and the Hβ equivalent width is 0.32 ± 0.32 Å, producing a formal [O III] λ5007/Hβ emission line ratio of 106 for a 3200 km s{sup –1} measurement aperture covering the full velocity width of the [O III] λ5007 line. Within a narrower 600 km s{sup –1} aperture covering the highest luminosity velocity structure in the line complex, we find [O III] λ5007/Hβ = 62. The measured [O III] λ5007/Hβ ratios are significantly higher than can be produced in radiative models of the emission line region with solar composition, and the confidence interval limits exclude all but models which have gas masses much larger than those for a single star. Therefore, we conclude that the region from which the [O III] λ5007 emission originates is hydrogen-depleted relative to solar composition gas. This finding is consistent with emission from an accretion-powered outflow driven by a hydrogen-depleted donor star, such as a white dwarf, being accreted onto a black hole.

  19. Microwave polarization angle study of the radiation-induced magnetoresistance oscillations in the GaAs/AlGaAs 2D electron system under dc current bias

    NASA Astrophysics Data System (ADS)

    Iqbal, Muhammad-Zahir; Liu, Han-Chun; Heimbeck, Martin S.; Everitt, Henry O.; Wegscheider, Werner; Mani, Ramesh G.

    Microwave-induced magnetoresistance oscillations followed by the vanishing resistance states are a prime representation of non-equilibrium transport phenomena in two-dimensional electron systems (2DES). The effect of a dc current bias on the nonlinear response of 2DES with microwave polarization angle under magnetic field is a subject of interest. Here, we have studied the effect of various dc current bias on microwave radiation-induced magnetoresistance oscillations in a high mobility 2DES. Further, we systematically investigate the effect of the microwave polarization angle on the magneto-resistance oscillations at two different frequencies 152.78 GHz and 185.76 GHz. This study aims to better understand the effects of both dc current and microwave polarization angle in the GaAs/AlGaAs system, both of which modify the observed magneto-transport properties DOE-BES, Mat'l. Sci. & Eng. Div., DE-SC0001762; ARO W911NF-14-2-0076; ARO W911NF-15-1-0433.

  20. Study of microwave reflection in the regime of the radiation-induced magnetoresistance oscillations in the high mobility GaAs/AlGaAs 2D electron system

    NASA Astrophysics Data System (ADS)

    Kriisa, Annika; Liu, H.-C.; Samaraweera, R. L.; Heimbeck, M. S.; Everitt, H. O.; Wegscheider, W.; Mani, R. G.

    Microwave-induced zero-resistance-states in the photo-excited GaAs/AlGaAs system evolve from the minima of microwave photo-excited ``quarter-cycle shifted'' magnetoresistance oscillations. Such magnetoresistance oscillations are known to exhibit nodes at cyclotron resonance (hf = ℏωc) and cyclotron resonance harmonics (hf = nℏωc). Further, the effective mass extracted from the radiation-induced magnetoresistance oscillations is known to differ from the canonical effective mass ratio for electrons in the GaAs/AlGaAs system. In an effort to reconcile this difference, we have looked for cyclotron resonance in the microwave reflection from the high mobility 2DES and attempted to correlate the observations with observed oscillatory magnetoresistance over the 30 <= f <= 330 GHz band. The results of such a study will be reported here. DOE-BES, Mat'l. Sci. & Eng. Div., DE-SC0001762; ARO W911NF-14-2-0076; ARO W911NF-15-1-0433.

  1. 2D time domain spectral phase encoding/wavelength hopping coherent DPSK-OCDMA system using fiber Bragg gratings and phase modulator

    NASA Astrophysics Data System (ADS)

    Gao, Zhensen; Dai, Bo; Wang, Xu; Kataoka, Nobuyuki; Wada, Naoya

    2010-12-01

    We propose and experimentally demonstrate a reconfigurable two-dimensional (temporal-spectral) time domain spectral phase encoding (SPE) scheme for coherent optical code-division-multiple-access (OCDMA) application. The time-domain SPE scheme is robust to wavelength drift of the light source and is very flexible and compatible with the fiber optical system. In the proposed scheme, the ultra-short optical pulse is stretched by dispersive device and the SPE is done in time domain using high speed phase modulator. A Fiber Bragg Gratings array is used for generating the two-dimensional wavelength hopping pattern while the high speed phase modulator is used for generating the spectral phase pattern. The proposed scheme can enable simultaneous generation of the time domain spectral phase encoding and DPSK data modulation using only a single phase modulator. In the experiment, the two-dimensional SPE codes have been generated and modulated with 2.5-Gb/s DPSK data using a single phase modulator. Transmission of the 2.5-Gb/s DPSK data over 49km fiber with BER<10-9 has been demonstrated successfully. The proposed scheme exhibits the potential to simplify the architecture and improve the security of the OCDMA system.

  2. Low-Resistance 2D/2D Ohmic Contacts: A Universal Approach to High-Performance WSe2, MoS2, and MoSe2Transistors

    NASA Astrophysics Data System (ADS)

    Chuang, Hsun-Jen; Chamlagain, Bhim; Koehler, Michael; Perera, Meeghage Madusanka; Yan, Jiaqiang; Mandrus, David; Tománek, David; Zhou, Zhixian

    2016-03-01

    We report a new strategy for fabricating 2D/2D low-resistance ohmic contacts for a variety of transition metal dichalcogenides (TMDs) using van der Waals assembly of substitutionally doped TMDs as drain/source contacts and TMDs with no intentional doping as channel materials. We demonstrate that few-layer WSe2 field-effect transistors (FETs) with 2D/2D contacts exhibit low contact resistances of ~ 0.3 k ohm.um, high on/off ratios up to > 109, and high drive currents exceeding 320 uA um-1. These favorable characteristics are combined with a two-terminal field-effect hole mobility ~ 2x102 cm2 V-1 s-1 at room temperature, which increases to >2x103 cm2 V-1 s-1 at cryogenic temperatures. We observe a similar performance also in MoS2 and MoSe2 FETs with 2D/2D drain and source contacts. The 2D/2D low-resistance ohmic contacts presented here represent a new device paradigm that overcomes a significant bottleneck in the performance of TMDs and a wide variety of other 2D materials as the channel materials in post-silicon electronics.

  3. Low-Resistance 2D/2D Ohmic Contacts: A Universal Approach to High-Performance WSe2, MoS2, and MoSe2 Transistors.

    PubMed

    Chuang, Hsun-Jen; Chamlagain, Bhim; Koehler, Michael; Perera, Meeghage Madusanka; Yan, Jiaqiang; Mandrus, David; Tománek, David; Zhou, Zhixian

    2016-03-01

    We report a new strategy for fabricating 2D/2D low-resistance ohmic contacts for a variety of transition metal dichalcogenides (TMDs) using van der Waals assembly of substitutionally doped TMDs as drain/source contacts and TMDs with no intentional doping as channel materials. We demonstrate that few-layer WSe2 field-effect transistors (FETs) with 2D/2D contacts exhibit low contact resistances of ∼0.3 kΩ μm, high on/off ratios up to >10(9), and high drive currents exceeding 320 μA μm(-1). These favorable characteristics are combined with a two-terminal field-effect hole mobility μFE ≈ 2 × 10(2) cm(2) V(-1) s(-1) at room temperature, which increases to >2 × 10(3) cm(2) V(-1) s(-1) at cryogenic temperatures. We observe a similar performance also in MoS2 and MoSe2 FETs with 2D/2D drain and source contacts. The 2D/2D low-resistance ohmic contacts presented here represent a new device paradigm that overcomes a significant bottleneck in the performance of TMDs and a wide variety of other 2D materials as the channel materials in postsilicon electronics. PMID:26844954

  4. Documenting the Effectiveness of Cosorption of Airborne Contaminants by a Field-Installed Active Desiccant System: Final Report - Phase 2D

    SciTech Connect

    Fischer, J

    2003-01-23

    The final report for Phase 1 of this research effort (ORNL/SUB/94-SV004/1) concluded that a significant market opportunity would exist for active desiccant systems if it could be demonstrated that they can remove a significant proportion of common airborne contaminants while simultaneously performing the primary function of dehumidifying a stream of outdoor air or recirculated building air. If the engineering community begins to follow the intent of ASHRAE Standard 62, now part of all major building codes, the outdoor air in many major cities may need to be pre-cleaned before it is introduced into occupied spaces. Common air contaminant cosorption capability would provide a solution to three important aspects of the ASHRAE 62-89 standard that have yet to be effectively addressed by heating, ventilation, and air-conditioning (HVAC) equipment manufacturers: (1) The ASHRAE standard defines acceptable outdoor air quality. If the outdoor air contains unacceptable levels of certain common outdoor air contaminants (e.g., sulfur dioxide, ozone), then the standard requires that these contaminants be removed from the outdoor air stream to reach compliance with the acceptable outdoor air quality guidelines. (2) Some engineers prefer to apply a filtration or prescriptive approach rather than a ventilation approach to solving indoor air quality problems. The ASHRAE standard recognizes this approach provided that the filtration technology exists to remove the gaseous contaminants encountered. The performance of current gaseous filtration technologies is not well documented, and they can be costly to maintain because the life of the filter is limited and the cost is high. Moreover, it is not easy to determine when the filters need changing. In such applications, an additional advantage provided by the active desiccant system would be that the same piece of equipment could control space humidity and provide filtration, even during unoccupied periods, if the active desiccant system

  5. A 2D domain decomposition, a customized immersed boundary method and a zest of numerical dissipation: a successful cocktail to tackle turbulence on HPC systems

    NASA Astrophysics Data System (ADS)

    Laizet, Sylvain; Lamballais, Eric; Vassilicos, J. Christos

    2015-11-01

    Incompact3d is a high-order flow solver dedicated to Direct and Large Eddy Simulations (DNS/LES) using High Performance Computing (HPC) systems which isdevoted to turbulent flows at the interface between academic research and upstream industrial R&D. It is originating from the University of Poitiers (France) and was developed there as well as, more recently, in the Turbulence, Mixing and Flow Control Group at Imperial College London (UK). This high-order flow solver can reconcile accuracy, efficiency, versatility and scalability using a simple Cartesian mesh and up to one million computational cores. The three key ingredients of this successful cocktail to tackle turbulence on HPC systemswill be given in this talkfollowed by various applications such as fractal-generated turbulence, gravity currents in an open basin, impinging jets on a heated plate and a micro-jet device to control a turbulent jet.

  6. M-theoretic derivations of 4d-2d dualities: from a geometric Langlands duality for surfaces, to the AGT correspondence, to integrable systems

    NASA Astrophysics Data System (ADS)

    Tan, Meng-Chwan

    2013-07-01

    In part I, we extend our analysis in [arXiv:0807.1107], and show that a mathematically conjectured geometric Langlands duality for complex surfaces in [1], and its generalizations — which relate some cohomology of the moduli space of certain ("ramified") G-instantons to the integrable representations of the Langlands dual of certain affine (sub) G-algebras, where G is any compact Lie group — can be derived, purely physically, from the principle that the spacetime BPS spectra of string-dual M-theory compactifications ought to be equivalent. In part II, to the setup in part I, we introduce Omega-deformation via fluxbranes and add half-BPS boundary defects via M9-branes, and show that the celebrated AGT correspondence in [2, 3], and its generalizations — which essentially relate, among other things, some equivariant cohomology of the moduli space of certain ("ramified") G-instantons to the integrable representations of the Langlands dual of certain affine -algebras — can likewise be derived from the principle that the spacetime BPS spectra of string-dual M-theory compactifications ought to be equivalent. In part III, we consider various limits of our setup in part II, and connect our story to chiral fermions and integrable systems. Among other things, we derive the NekrasovOkounkov conjecture in [4] — which relates the topological string limit of the dual Nekrasov partition function for pure G to the integrable representations of the Langlands dual of an affine G-algebra — and also demonstrate that the Nekrasov-Shatashvili limit of the "fullyramified" Nekrasov instanton partition function for pure G is a simultaneous eigenfunction of the quantum Toda Hamiltonians associated with the Langlands dual of an affine G-algebra. Via the case with matter, we also make contact with Hitchin systems and the "ramified" geometric Langlands correspondence for curves.

  7. 2D-QSPR/DFT studies of aryl-substituted PNP-Cr-based catalyst systems for highly selective ethylene oligomerization.

    PubMed

    Tang, Siyang; Liu, Zhen; Zhan, Xingwen; Cheng, Ruihua; He, Xuelian; Liu, Boping

    2014-03-01

    1-Hexene and 1-octene are important comonomers for the synthesis of high performance polyolefins. Recently, various N-substituted Cr-bis(diphenylphosphino)amine (PNP-Cr) catalysts show the potential as excellent candidates for highly selective ethylene trimerization/tetramerization. In this work, a series of aryl-substituted PNP-Cr catalysts were studied by two-dimensional quantitative structure-property relationship (QSPR) method based on density functional theory (DFT) calculations. The heuristic method (HM) and best multi-linear regression (BMLR) were used to establish the best linear regression models to describe the relationship between selectivities and catalyst structures. Both Cr(I) and Cr(II) active site models for ethylene trimerization/tetramerization were considered. It was found that 1) the relativity and stability of the models were increased by using self-defined descriptors based on DFT calculations; 2) Cr(I)/Cr(III) centers were the most plausible active sites for ethylene trimerization, while Cr(II)/Cr(IV) active sites were most possibly responsible for ethylene tetramerization; and 3) the skeleton structures of the PNP-Cr system with good complanation and symmetry were crucial for achieving excellent catalytic selectivity of 1-octene, while the PNP-Cr backbone with a large steric effect on N atom would benefit ethylene trimerization. Six new PNP ligands with high selectivity toward ethylene trimerization/tetramerization were predicted based on descriptor analysis and the best linear regression models providing a good basis for further development of novel catalyst systems with better performance. PMID:24554126

  8. NKG2D ligands as therapeutic targets

    PubMed Central

    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

  9. Application of 2D VSP Imaging Technology to the Targeting of Exploration and Production Wells in a Basin and Range Geothermal System

    SciTech Connect

    Ellis, Richard K.

    2013-01-01

    The Humboldt House-Rye Patch geothermal resource area (HH-RP) comprises approximately 12,000 acres along and west of the Humboldt Range, adjacent to the Rye Patch Reservoir (Figure 1). A Federal Geothermal Unit covers essentially all of the known shallow thermal anomaly at the site, and the Operator, Presco Energy, is in the process of completing wellfield development adjacent to the Rye Patch binary plant, a nominal 17-megawatt system in the southern Unit area (Figure 1). DOE award EE0002840, made under the auspices of the Geothermal Technologies Program, was originally approved in January of 2010, and used a VSP profiling technology to improve seismic imaging in the Basin and Range. Phase I field activities were conducted in the 3rd quarter of 2010, and both the Phase I report and a supplemental report were completed in March and April of 2011. Two targets were identified for tests of upflow structures, both using existing wellbores, originally the 51-21 and 52-28, in the Rye Patch wellfield. The Phase II validation was approved by DOE in May of 2011.

  10. Effect of Initial Conditions on 2D Rayleigh-Taylor Instability and Transition to Turbulence in Planar Blast-wave-driven Systems

    SciTech Connect

    Miles, A R; Edwards, M J; Greenough, J A

    2004-03-26

    Perturbations on an interface driven by a strong blast wave grow in time due to a combination of Rayleigh-Taylor, Richtmyer-Meshkov, and decompression effects. In this paper, we present the first results from a computational study of such a system under drive conditions to be attainable on the National Ignition Facility. Using the multiphysics, AMR, higher order Godunov Eulerian hydrocode, Raptor, we consider the late nonlinear instability evolution for multiple amplitude and phase realizations of a variety of multimode spectral types. We show that compressibility effects preclude the emergence of a regime of self-similar instability growth independent of the initial conditions by allowing for memory of the initial conditions to be retained in the mix width at all times. The loss of transverse spectral information is demonstrated, however, along with the existence of a quasi-self-similar regime over short time intervals. Certain aspects of the initial conditions, including the rms amplitude, are shown to have a strong effect on the time to transition to the quasi-self-similar regime.

  11. Mn concentration-dependent tuning of Mn(2+) d emission of Zn1-xMnxTe nanocrystals grown in a glass system.

    PubMed

    Silva, Alessandra S; Lourenço, Sidney A; Dantas, Noelio O

    2016-02-17

    We studied the effect of Mn concentration on the optical, morphological and magnetic properties of Zn1-xMnxTe NCs grown in a glass matrix produced by the fusion method. The physical properties of these materials were determined by optical absorption (OA), transmission electron microscopy (TEM), atomic/magnetic force microscopy (AFM/MFM) and photoluminescence (PL). An analysis of the OA spectra, based on the crystal field theory (CFT), showed strong evidence that Mn(2+) ions were substitutionally incorporated into the Zn1-xMnxTe NCs until reaching the solubility limit (concentration, x = 0.100). Above this nominal concentration, TEM showed the onset of Mn-related phases, such as MnO and α-MnO2, in the PZABP glass system. AFM images showed that NC density on the surface of the glass matrix decreased as x-content increased. It is probable that MnO and MnO2 NCs would outnumber Zn1-xMnxTe NCs at higher concentrations - a conclusion that was corroborated by the OA spectra and TEM images. MFM images revealed that samples with Mn(2+) ions responded to magnetization from an MFM probe. This implied that Mn(2+) ions were incorporated within the Zn1-xMnxTe NCs and gave rise to the diluted magnetic semiconductor (DMS) structure. The PL spectra not only confirmed the evidence obtained by OA, CFT, TEM and AFM/MFM, but also showed that Mn(2+) concentration could be used to tune (4)T1((4)G) → (6)A1((6)S) emission energy. PMID:26844704

  12. Full scale Kick Detection System Testing relevant for slim-hole/HPHT drilling

    SciTech Connect

    Steine, O.G.; Rommetveit, R.; Harris, T.W.R.

    1995-12-31

    During June 1994 tests in the project {open_quotes}HPHT Kick Detection System Testing{close_quotes} were performed in Ullrigg well U-2. Experimental parameters such as influx type (liquid/gas), gas concentration, kick injection rate, flow rate, rpm`s, pipe reciprocation, pump speed changes, etc. were varied. Three kick detection systems were operating during the experiments. Two delta flow systems were supplied by Baker Hughes INTEQ (DrillByte {open_quotes}Kick detect{close_quotes} and {open_quotes}KDS{close_quotes}) and one acoustic system was provided by Smedvig (Gas Kick Warner). In addition, the Petreco J-Meter flow out measuring device was also tested. A total number of 14 kicks were performed during these experiments. The majority of kicks were performed at slim hole conditions. Raw data files containing approx. 14 Mbytes of downhole pressure data from bottom P-sensor, and surface data have been gathered for further analysis. The data was of high quality and provide opportunities to improve existing well control procedures and to incorporate this knowledge into future drilling operations. This paper summarizes the experimental conditions during which data were recorded, main results and operational recommendations.

  13. Black holes

    PubMed Central

    Brügmann, B.; Ghez, A. M.; Greiner, J.

    2001-01-01

    Recent progress in black hole research is illustrated by three examples. We discuss the observational challenges that were met to show that a supermassive black hole exists at the center of our galaxy. Stellar-size black holes have been studied in x-ray binaries and microquasars. Finally, numerical simulations have become possible for the merger of black hole binaries. PMID:11553801

  14. Documentation and verification of VST2D; a model for simulating transient, Variably Saturated, coupled water-heat-solute Transport in heterogeneous, anisotropic 2-Dimensional, ground-water systems with variable fluid density

    USGS Publications Warehouse

    Friedel, Michael J.

    2001-01-01

    This report describes a model for simulating transient, Variably Saturated, coupled water-heatsolute Transport in heterogeneous, anisotropic, 2-Dimensional, ground-water systems with variable fluid density (VST2D). VST2D was developed to help understand the effects of natural and anthropogenic factors on quantity and quality of variably saturated ground-water systems. The model solves simultaneously for one or more dependent variables (pressure, temperature, and concentration) at nodes in a horizontal or vertical mesh using a quasi-linearized general minimum residual method. This approach enhances computational speed beyond the speed of a sequential approach. Heterogeneous and anisotropic conditions are implemented locally using individual element property descriptions. This implementation allows local principal directions to differ among elements and from the global solution domain coordinates. Boundary conditions can include time-varying pressure head (or moisture content), heat, and/or concentration; fluxes distributed along domain boundaries and/or at internal node points; and/or convective moisture, heat, and solute fluxes along the domain boundaries; and/or unit hydraulic gradient along domain boundaries. Other model features include temperature and concentration dependent density (liquid and vapor) and viscosity, sorption and/or decay of a solute, and capability to determine moisture content beyond residual to zero. These features are described in the documentation together with development of the governing equations, application of the finite-element formulation (using the Galerkin approach), solution procedure, mass and energy balance considerations, input requirements, and output options. The VST2D model was verified, and results included solutions for problems of water transport under isohaline and isothermal conditions, heat transport under isobaric and isohaline conditions, solute transport under isobaric and isothermal conditions, and coupled water

  15. NKG2D receptor and its ligands in host defense

    PubMed Central

    Lanier, Lewis L.

    2015-01-01

    NKG2D is an activating receptor expressed on the surface of natural killer (NK) cells, CD8+ T cells, and subsets of CD4+ T cells, iNKT cells, and γδ T cells. In humans NKG2D transmits signals by its association with the DAP10 adapter subunit and in mice alternatively spliced isoforms transmit signals either using DAP10 or DAP12 adapter subunits. Although NKG2D is encoded by a highly conserved gene (KLRK1) with limited polymorphism, the receptor recognizes an extensive repertoire of ligands, encoded by at least 8 genes in humans (MICA, MICB, RAET1E, RAET1G, RAET1H, RAET1I, RAET1L, and RAET1N), some with extensive allelic polymorphism. Expression of the NKG2D ligands is tightly regulated at the level of transcription, translation, and post-translation. In general healthy adult tissues do not express NKG2D glycoproteins on the cell surface, but these ligands can be induced by hyper-proliferation and transformation, as well as when cells are infected by pathogens. Thus, the NKG2D pathway serves a mechanism for the immune system to detect and eliminate cells that have undergone “stress”. Viruses and tumor cells have devised numerous strategies to evade detection by the NKG2D surveillance system and diversification of the NKG2D ligand genes likely has been driven by selective pressures imposed by pathogens. NKG2D provides an attractive target for therapeutics in the treatment of infectious diseases, cancer, and autoimmune diseases. PMID:26041808

  16. Vitamin D delays breast cancer progression in the PyVMT transgenic mouse model: local conversion of the precursor 25(OH)D3 into 1,25(OH)2D3 is safer and more effective than systemic administration of 1,25(OH)2D3

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Metabolic activation of 1,25(OH)2D3 occurs at extra renal sites in several organs, including the breast. The purpose of this study was to determine if this local tumoral 25OHD3-1alphahydroxylase expression modulates any or all of the stages of breast tumor progression. For this purpose we used the...

  17. Prospects for Probing Strong Gravity with a Pulsar-Black Hole System

    NASA Technical Reports Server (NTRS)

    Wex, N.; Liu, K.; Eatough, R. P.; Kramer, M.; Cordes, J. M.; Lazio, T. J. W.

    2012-01-01

    The discovery of a pulsar (PSR) in orbit around a black hole (BH) is expected to provide a superb new probe of relativistic gravity and BH properties. Apart from a precise mass measurement for the BH, one could expect a clean verification of the dragging of space-time caused by the BH spin. In order to measure the quadrupole moment of the BH for testing the no-hair theorem of general relativity (GR), one has to hope for a sufficiently massive BH. In this respect, a PSR orbiting the super-massive BH in the center of our Galaxy would be the ultimate laboratory for gravity tests with PSRs. But even for gravity theories that predict the same properties for BHs as GR, a PSR-BH system would constitute an excellent test system, due to the high grade of asymmetry in the strong field properties of these two components. Here we highlight some of the potential gravity tests that one could expect from different PSR-BH systems.

  18. The Dynamics of Dense Stellar Systems with a Massive Central Black Hole

    NASA Astrophysics Data System (ADS)

    Gill, Michael A.

    In this work, we explore the dynamics of two similar types of dense stellar systems with a central black hole of mass much greater than a typical stellar object. In particular, we use numerical N-body simulations to examine the effects that the massive black hole (MBH) has on the surrounding stars and compact objects as they pertain to indirectly observable signals. The first systems we consider are the highly uncertain cusps likely comprised of primarily massive compact objects that surround the MBHs at the center of typical galaxies. The gradual inspiral of a compact object by emission of gravitational radiation, called an extreme mass-ratio inspiral (EMRI), will produce a signal that falls in the peak detection range of the space-bound laser interferometer space antenna (LISA). Despite a veritable gold mine of astrophysical data that could be gleaned from such a detection, previous investigations in the literature have left the predicted rate of these events uncertain by several orders of magnitude. We present direct N-body simulations of the innermost ≤ 100 objects with the inclusion of the first-order Post-Newtonian correction with the aim of reducing one of the key uncertainties in the dynamics of these systems - the efficiency of resonant relaxation. We find that relativistic pericenter precession prevents a significant enhancement of the EMRI rate; the rate we derive during this work is consistent with those derived in the literature from less direct methods. We do find, however, that our EMRI progenitors originate from much closer to the MBH than previous investigations have suggested was likely. Our second investigation delves into the possibility of finding intermediate-mass black holes (IMBHs), with masses ˜ 102-4 Msun , at the center of dense star clusters. Because of the substantial investment of telescope time needed to perform the multiyear proper motion studies that are likely needed to achieve a definitive detection, careful selection of

  19. Black Holes

    NASA Astrophysics Data System (ADS)

    Livio, Mario; Koekemoer, Anton M.

    2011-02-01

    Participants; Preface Mario Livio and Anton Koekemoer; 1. Black holes, entropy, and information G. T. Horowitz; 2. Gravitational waves from black-hole mergers J. G. Baker, W. D. Boggs, J. M. Centrella, B. J. Kelley, S. T. McWilliams and J. R. van Meter; 3. Out-of-this-world physics: black holes at future colliders G. Landsberg; 4. Black holes in globular clusters S. L. W. McMillan; 5. Evolution of massive black holes M. Volonteri; 6. Supermassive black holes in deep multiwavelength surveys C. M. Urry and E. Treister; 7. Black-hole masses from reverberation mapping B. M. Peterson and M. C. Bentz; 8. Black-hole masses from gas dynamics F. D. Macchetto; 9. Evolution of supermassive black holes A. Müller and G. Hasinger; 10. Black-hole masses of distant quasars M. Vestergaard; 11. The accretion history of supermassive black holes K. Brand and the NDWFS Boötes Survey Teams; 12. Strong field gravity and spin of black holes from broad iron lines A. C. Fabian; 13. Birth of massive black-hole binaries M. Colpi, M. Dotti, L. Mayer and S. Kazantzidis; 14. Dynamics around supermassive black holes A. Gualandris and D. Merritt; 15. Black-hole formation and growth: simulations in general relativity S. L. Shapiro; 16. Estimating the spins of stellar-mass black holes J. E. McClintock, R. Narayan and R. Shafee; 17. Stellar relaxation processes near the Galactic massive black hole T. Alexander; 18. Tidal disruptions of stars by supermassive black holes S. Gezari; 19. Where to look for radiatively inefficient accretion flows in low-luminosity AGN M. Chiaberge; 20. Making black holes visible: accretion, radiation, and jets J. H. Krolik.

  20. Numerical Evaluation of 2D Ground States

    NASA Astrophysics Data System (ADS)

    Kolkovska, Natalia

    2016-02-01

    A ground state is defined as the positive radial solution of the multidimensional nonlinear problem \\varepsilon propto k_ bot 1 - ξ with the function f being either f(u) =a|u|p-1u or f(u) =a|u|pu+b|u|2pu. The numerical evaluation of ground states is based on the shooting method applied to an equivalent dynamical system. A combination of fourth order Runge-Kutta method and Hermite extrapolation formula is applied to solving the resulting initial value problem. The efficiency of this procedure is demonstrated in the 1D case, where the maximal difference between the exact and numerical solution is ≈ 10-11 for a discretization step 0:00025. As a major application, we evaluate numerically the critical energy constant. This constant is defined as a functional of the ground state and is used in the study of the 2D Boussinesq equations.

  1. 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.

  2. 2D Electrostatic Actuation of Microshutter Arrays

    NASA Technical Reports Server (NTRS)

    Burns, Devin E.; Oh, Lance H.; Li, Mary J.; Kelly, Daniel P.; Kutyrev, Alexander S.; Moseley, Samuel H.

    2015-01-01

    Electrostatically actuated microshutter arrays 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 microshutters 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.

  3. Perspectives for spintronics in 2D materials

    NASA Astrophysics Data System (ADS)

    Han, Wei

    2016-03-01

    The past decade has been especially creative for spintronics since the (re)discovery of various two dimensional (2D) materials. Due to the unusual physical characteristics, 2D materials have provided new platforms to probe the spin interaction with other degrees of freedom for electrons, as well as to be used for novel spintronics applications. This review briefly presents the most important recent and ongoing research for spintronics in 2D materials.

  4. Formation of Black Hole Low-mass X-Ray Binaries in Hierarchical Triple Systems

    NASA Astrophysics Data System (ADS)

    Naoz, Smadar; Fragos, Tassos; Geller, Aaron; Stephan, Alexander P.; Rasio, Frederic A.

    2016-05-01

    The formation of black hole (BH) low-mass X-ray binaries (LMXB) poses a theoretical challenge, as low-mass companions are not expected to survive the common-envelope scenario with the BH progenitor. Here we propose a formation mechanism that skips the common-envelope scenario and relies on triple-body dynamics. We study the evolution of hierarchical triples following the secular dynamical evolution up to the octupole-level of approximation, including general relativity, tidal effects, and post-main-sequence evolution such as mass loss, changes to stellar radii, and supernovae. During the dynamical evolution of the triple system the “eccentric Kozai-Lidov” mechanism can cause large eccentricity excitations in the LMXB progenitor, resulting in three main BH-LMXB formation channels. Here we define BH-LMXB candidates as systems where the inner BH-companion star crosses its Roche limit. In the “eccentric” channel (∼81% of the LMXBs in our simulations) the donor star crosses its Roche limit during an extreme eccentricity excitation while still on a wide orbit. Second, we find a “giant” LMXB channel (∼11%), where a system undergoes only moderate eccentricity excitations but the donor star fills its Roche-lobe after evolving toward the giant branch. Third, we identify a “classical” channel (∼8%), where tidal forces and magnetic braking shrink and circularize the orbit to short periods, triggering mass-transfer. Finally, for the giant channel we predict an eccentric (∼0.3–0.6) preferably inclined (∼40°, ∼140°) tertiary, typically on a wide enough orbit (∼104 au) to potentially become unbound later in the triple evolution. While this initial study considers only one representative system and neglects BH natal kicks, we expect our scenario to apply across a broad region of parameter space for triple-star systems.

  5. Formation of the black-hole binary M33 X-7 through mass exchange in a tight massive system.

    PubMed

    Valsecchi, Francesca; Glebbeek, Evert; Farr, Will M; Fragos, Tassos; Willems, Bart; Orosz, Jerome A; Liu, Jifeng; Kalogera, Vassiliki

    2010-11-01

    The X-ray source M33 X-7 in the nearby galaxy Messier 33 is among the most massive X-ray binary stellar systems known, hosting a rapidly spinning, 15.65M(⊙) black hole orbiting an underluminous, 70M(⊙) main-sequence companion in a slightly eccentric 3.45-day orbit (M(⊙), solar mass). Although post-main-sequence mass transfer explains the masses and tight orbit, it leaves unexplained the observed X-ray luminosity, the star's underluminosity, the black hole's spin and the orbital eccentricity. A common envelope phase, or rotational mixing, could explain the orbit, but the former would lead to a merger and the latter to an overluminous companion. A merger would also ensue if mass transfer to the black hole were invoked for its spin-up. Here we report simulations of evolutionary tracks which reveal that if M33 X-7 started as a primary body of 85M(⊙)-99M(⊙) and a secondary body of 28M(⊙)-32M(⊙), in a 2.8-3.1-d orbit, its observed properties can be consistently explained. In this model, the main-sequence primary transfers part of its envelope to the secondary and loses the rest in a wind; it ends its life as a ∼16M(⊙) helium star with an iron-nickel core that collapses to a black hole (with or without an accompanying supernova). The release of binding energy, and possibly collapse asymmetries, 'kick' the nascent black hole into an eccentric orbit. Wind accretion explains the X-ray luminosity, and the black-hole spin can be natal. PMID:20962778

  6. Formation of the black-hole binary M33 X-7 through mass exchange in a tight massive system

    NASA Astrophysics Data System (ADS)

    Valsecchi, Francesca; Glebbeek, Evert; Farr, Will M.; Fragos, Tassos; Willems, Bart; Orosz, Jerome A.; Liu, Jifeng; Kalogera, Vassiliki

    2010-11-01

    The X-ray source M33 X-7 in the nearby galaxy Messier 33 is among the most massive X-ray binary stellar systems known, hosting a rapidly spinning, 15.65Msolar black hole orbiting an underluminous, 70Msolar main-sequence companion in a slightly eccentric 3.45-day orbit (Msolar, solar mass). Although post-main-sequence mass transfer explains the masses and tight orbit, it leaves unexplained the observed X-ray luminosity, the star's underluminosity, the black hole's spin and the orbital eccentricity. A common envelope phase, or rotational mixing, could explain the orbit, but the former would lead to a merger and the latter to an overluminous companion. A merger would also ensue if mass transfer to the black hole were invoked for its spin-up. Here we report simulations of evolutionary tracks which reveal that if M33 X-7 started as a primary body of 85Msolar-99Msolar and a secondary body of 28Msolar-32Msolar, in a 2.8-3.1-d orbit, its observed properties can be consistently explained. In this model, the main-sequence primary transfers part of its envelope to the secondary and loses the rest in a wind; it ends its life as a ~16Msolar helium star with an iron-nickel core that collapses to a black hole (with or without an accompanying supernova). The release of binding energy, and possibly collapse asymmetries, `kick' the nascent black hole into an eccentric orbit. Wind accretion explains the X-ray luminosity, and the black-hole spin can be natal.

  7. Suspended 2-D photonic crystal aluminum nitride membrane reflector.

    PubMed

    Ho, Chong Pei; Pitchappa, Prakash; Soon, Bo Woon; Lee, Chengkuo

    2015-04-20

    We experimentally demonstrated a free-standing two-dimensional (2-D) photonic crystal (PhC) aluminum nitride (AlN) membrane to function as a free space (or out-of-plane) reflector working in the mid infrared region. By etching circular holes of radius 620nm in a 330nm thick AlN slab, greater than 90% reflection was measured from 3.08μm to 3.78μm, with the peak reflection of 96% at 3.16μm. Due to the relatively low refractive index of AlN, we also investigated the importance of employing methods such as sacrificial layer release to enhance the performance of the PhC. In addition, characterization of the AlN based PhC was also done up to 450°C to examine the impact of thermo-optic effect on the performance. Despite the high temperature operation, the redshift in the peak reflection wavelengths of the device was estimated to be only 14.1nm. This equates to a relatively low thermo-optic coefficient 2.22 × 10(-5) K(-1) for AlN. Such insensitivity to thermo-optic effect makes AlN based 2-D PhC a promising technology to be used as photonic components for high temperature applications such as Fabry-Perot interferometer used for gas sensing in down-hole oil drilling and ruggedized electronics. PMID:25969099

  8. Collective excitations in 2D hard-disc fluid.

    PubMed

    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

  9. Efficient framework for deformable 2D-3D registration

    NASA Astrophysics Data System (ADS)

    Fluck, Oliver; Aharon, Shmuel; Khamene, Ali

    2008-03-01

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

  10. Fractional Quantum Hall Effect at ν = 1 / 2 in Hole Systems Confined to GaAs Wide Quantum Wells

    NASA Astrophysics Data System (ADS)

    Hasdemir, Sukret; Liu, Yang; Graninger, Aurelius; Shayegan, Mansour; Pfeiffer, Loren; West, Ken; Baldwin, Kirk; Winkler, Roland

    2014-03-01

    We observe fractional quantum Hall effect (FQHE) at the even-denominator Landau level filling factor ν = 1 / 2 in two-dimensional hole systems confined to GaAs quantum wells of width 30 to 50 nm and having bilayer-like charge distributions. The ν = 1 / 2 FQHE is stable when the charge distribution is symmetric and only in a range of intermediate densities, qualitatively similar to what is seen in two-dimensional electron systems confined to approximately twice wider GaAs quantum wells. Despite the complexity of the hole Landau level structure, originating from the coexistence and mixing of the heavy- and light-hole states, we find the hole ν = 1 / 2 FQHE to be consistent with a two-component, Halperin-Laughlin (Ψ331) state. We acknowledge support through the DOE BES (DE-FG02-00-ER45841) for measurements, and the Gordon and Betty Moore Foundation (Grant GBMF2719), Keck Foundation, and the NSF (DMR-0904117, DMR-1305691 and MRSEC DMR-0819860) for sample fabrication. Work at Arg.

  11. Comparison of 2D and 3D gamma analyses

    SciTech Connect

    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

  12. A small-animal imaging system capable of multipinhole circular/helical SPECT and parallel-hole SPECT

    PubMed Central

    Qian, Jianguo; Bradley, Eric L.; Majewski, Stan; Popov, Vladimir; Saha, Margaret S.; Smith, Mark F.; Weisenberger, Andrew G.; Welsh, Robert E.

    2008-01-01

    We have designed and built a small animal single photon emission computed tomography (SPECT) imaging system equipped with parallel-hole and multipinhole collimators and capable of circular or helical SPECT. Copper-beryllium parallel-hole collimators suitable for imaging the ~35 keV photons from the decay of 125I have been built and installed to achieve useful spatial resolution over a range of object-detector distances and to reduce imaging time on our dual-detector array. To address the resolution limitations in the parallel-hole SPECT and the sensitivity and limited field of view of single-pinhole SPECT, we have incorporated multipinhole circular and helical SPECT in addition to expanding the parallel-hole SPECT capabilities. The pinhole SPECT system is based on a 110 mm diameter circular detector equipped with a pixellated NaI(Tl) scintillator array (1×1×5 mm3/pixel). The helical trajectory is accomplished by two stepping motors controlling the rotation of the detector-support gantry and displacement of the animal bed along the axis of rotation of the gantry. Results obtained in SPECT studies of various phantoms show an enlarged field of view, very good resolution and improved sensitivity using multipinhole circular or helical SPECT. Collimators with one, three and five 1 mm diameter pinholes have been implemented and compared in these tests. Our objective is to develop a system on which one may readily select a suitable mode of either parallel-hole SPECT or pinhole circular or helical SPECT for a variety of small animal imaging applications. PMID:19701447

  13. A small-animal imaging system capable of multipinhole circular/helical SPECT and parallel-hole SPECT

    NASA Astrophysics Data System (ADS)

    Qian, Jianguo; Bradley, Eric L.; Majewski, Stan; Popov, Vladimir; Saha, Margaret S.; Smith, Mark F.; Weisenberger, Andrew G.; Welsh, Robert E.

    2008-08-01

    We have designed and built a small-animal single-photon emission computed tomography (SPECT) imaging system equipped with parallel-hole and multipinhole collimators and capable of circular or helical SPECT. Copper-beryllium parallel-hole collimators suitable for imaging the ˜35 keV photons from the decay of 125I have been built and installed to achieve useful spatial resolution over a range of object-detector distances and to reduce imaging time on our dual-detector array. To address the resolution limitations in the parallel-hole SPECT and the sensitivity and limited field of view of single-pinhole SPECT, we have incorporated multipinhole circular and helical SPECT in addition to expanding the parallel-hole SPECT capabilities. The pinhole SPECT system is based on a 110 mm diameter circular detector equipped with a pixellated NaI(Tl) scintillator array (1×1×5 mm 3/pixel). The helical trajectory is accomplished by two stepping motors controlling the rotation of the detector-support gantry and displacement of the animal bed along the axis of rotation of the gantry. Results obtained in SPECT studies of various phantoms show an enlarged field of view, very good resolution and improved sensitivity using multipinhole circular or helical SPECT. Collimators with one, three and five, 1-mm-diameter pinholes have been implemented and compared in these tests. Our objective is to develop a system on which one may readily select a suitable mode of either parallel-hole SPECT or pinhole circular or helical SPECT for a variety of small animal imaging applications.

  14. Fast magnetoacoustic wave trains in coronal holes

    NASA Astrophysics Data System (ADS)

    Pascoe, D. J.; Nakariakov, V. M.; Kupriyanova, E. G.

    2014-08-01

    Context. Rapidly propagating coronal EUV disturbances recently discovered in the solar corona are interpreted in terms of guided fast magnetoacoustic waves. Fast magnetoacoustic waves experience geometric dispersion in waveguides, which causes localised, impulsive perturbations to develop into quasi-periodic wave trains. Aims: We consider the formation of fast wave trains in a super-radially expanding coronal hole modelled by a magnetic funnel with a field-aligned density profile that is rarefied in comparison to the surrounding plasma. This kind of structure is typical of coronal holes, and it forms a fast magnetoacoustic anti-waveguide as a local maximum in the Alfvén speed. Methods: We performed 2D MHD numerical simulations for impulsively generated perturbations to the system. Both sausage and kink perturbations are considered and the role of the density contrast ratio investigated. Results: The anti-waveguide funnel geometry refracts wave energy away from the structure. However, in this geometry the quasi-periodic fast wave trains are found to appear, too, and so can be associated with the observed rapidly propagating coronal EUV disturbances. The wave trains propagate along the external edge of the coronal hole. The fast wave trains generated in coronal holes exhibit less dispersive evolution than in the case of a dense waveguide. Conclusions: We conclude that an impulsive energy release localised in a coronal plasma inhomogeneity develops into a fast wave train for both kink and sausage disturbances and for both waveguide and anti-waveguide transverse plasma profiles.

  15. Annotated Bibliography of EDGE2D Use

    SciTech Connect

    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.

  16. Generating functional approach for spontaneous coherence in semiconductor electron-hole-photon systems

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Makoto; Nii, Ryota; Kamide, Kenji; Ogawa, Tetsuo; Yamamoto, Yoshihisa

    2015-03-01

    Electrons, holes, and photons in semiconductors are interacting fermions and bosons. In this system, a variety of ordered coherent phases can be formed through the spontaneous phase symmetry breaking because of their interactions. The Bose-Einstein condensation (BEC) of excitons and polaritons is one of such coherent phases, which can potentially cross over into the Bardeen-Cooper-Schrieffer (BCS) type ordered phase at high densities under quasiequilibrium conditions, known as the BCS-BEC crossover. In contrast, one can find the semiconductor laser, superfluorescence (SF), and superradiance as relevant phenomena under nonequilibrium conditions. In this paper, we present a comprehensive generating functional theory that yields nonequilibrium Green's functions in a rigorous way. The theory gives us a starting point to discuss these phases in a unified view with a diagrammatic technique. Comprehensible time-dependent equations are derived within the Hartree-Fock approximation, which generalize the Maxwell-semiconductor-Bloch equations under the relaxation time approximation. With the help of this formalism, we clarify the relationship among these cooperative phenomena and we show theoretically that the Fermi-edge SF is directly connected to the e-h BCS phase. We also discuss the emission spectra as well as the gain-absorption spectra.

  17. Thermopower of interacting double-layer hole systems near ν = 1.

    NASA Astrophysics Data System (ADS)

    Melinte, S.; Faniel, S.; Bayot, V.; Tutuc, E.; Shayegan, M.

    2004-03-01

    We report on thermopower measurements performed on an interacting GaAs bilayer hole system in the limit of no interlayer tunneling. The sample consists of two GaAs quantum wells with thicknesses of 15 nm separated by a 7.5 nm wide AlAs barrier and has total density of 5 × 10^10 cm-2. By means of top and back gates we can independently control the densities of the two layers. When the density of the two different layers is made equal the quantum Hall state at filling factor ν = 1 is flanked by a re-entrant insulating phase (IP)(E. Tutuc phet al.), Phys. Rev. Lett. 91, 076802 (2003). When charge is transfered from one layer to the other, this phase disappears. We study the temperature and ν dependence of the Seebeck coefficient near ν = 1 in a dilution refrigerator for both balanced and imbalanced configurations in order to determine the ground state properties of the IP.

  18. A hybrid fiber-optic sensing system for down-hole pressure and distributed temperature measurements

    NASA Astrophysics Data System (ADS)

    Chen, Ke; Zhou, Xinlei; Yang, Bokai; Peng, Wei; Yu, Qingxu

    2015-10-01

    A hybrid fiber-optic sensing technique, combining the extrinsic Fabry-Perot interferometer (EFPI) based pressure sensor with the incoherent optical frequency domain reflectometry (IOFDR) based distributed temperature sensor (DTS), is presented for down-hole measurements. By using a laser diode as the common light source, a highly integrated hybrid EFPI/DTS sensing system has been developed with a single fiber. With the injection current of the laser diode below lasing threshold, the broadband spontaneous emission light is used for EFPI based pressure sensing; while with the injection current above the threshold, the stimulated emission light is used for Raman based distributed temperature sensing. There is no overlap between the spectral range of the reflected light from the EFPI sensor and the spectral range of the Raman scattered light. Pressure and distributed temperature can thus be measured by using wavelength-division multiplexing (WDM) technology. Experimental results show that both the pressure and the distributed temperature are measured with little interference. Furthermore, the pressure measurement can be compensated by the measured temperature values.

  19. Resolving 2D Amorphous Materials with Scanning Probe Microscopy

    NASA Astrophysics Data System (ADS)

    Burson, Kristen M.; Buechner, Christin; Lewandowski, Adrian; Heyde, Markus; Freund, Hans-Joachim

    Novel two-dimensional (2D) materials have garnered significant scientific interest due to their potential technological applications. Alongside the emphasis on crystalline materials, such as graphene and hexagonal BN, a new class of 2D amorphous materials must be pursued. For amorphous materials, a detailed understanding of the complex structure is necessary. Here we present a structural study of 2D bilayer silica on Ru(0001), an insulating material which is weakly coupled to the substrate. Atomic structure has been determined with a dual mode atomic force microscopy (AFM) and scanning tunneling microscopy (STM) sensor in ultra-high vacuum (UHV) at low temperatures, revealing a network of different ring sizes. Liquid AFM measurements with sub-nanometer resolution bridge the gap between clean UHV conditions and the environments that many material applications demand. Samples are grown and characterized in vacuum and subsequently transferred to the liquid AFM. Notably, the key structural features observed, namely nanoscale ring networks and larger holes to the substrate, show strong quantitative agreement between the liquid and UHV microscopy measurements. This provides direct evidence for the structural stability of these silica films for nanoelectronics and other applications. KMB acknowledges support from the Alexander von Humboldt Foundation.

  20. Emerging Picture of Black Hole in Double-Star System Promises Exciting Yield of New Physics Data

    NASA Astrophysics Data System (ADS)

    1995-06-01

    As scientists from the National Radio Astronomy Observatory (NRAO) report on analysis of "moving pictures" of powerful jets of material emerging from a double-star system 10,000 light-years away, new evidence from other research confirms that the source of the jets is a black hole. A series of images made with the Very Long Baseline Array (VLBA) and Very Large Array (VLA) radio telescopes, made by Robert Hjellming and Michael Rupen of NRAO, appears in the June 8 issue of the scientific journal Nature. When these radio "snapshots" of jets emerging from an X-ray nova in the constellation Scorpius were made in August and September of 1994, the source of the jets was only suspected of harboring a black hole. It is now certain that a black hole is the source of the jets, thanks to an intense observing effort using ground-and space-based telescopes at wavelengths ranging from gamma rays to radio waves. The system, discovered only last year, with a star similar in size to our Sun orbiting the black hole, now promises to show astronomers -- at long last -- details of how black holes can power super-energetic jets of material to nearly the speed of light. The latest results come from studies made with radio and optical telescopes operated for the National Science Foundation. Black holes are concentrations of matter so dense that their gravitational attraction prevents even light from escaping them. "This is the first time we can say that one of the components of a jet-emitting binary is a black hole based on fundamental astronomy, rather than on fitting observational data to complicated models," said Hjellming, an NRAO astronomer in Socorro, NM. This resulted from observations of the object -- called GRO J1655-40 -- with instruments covering widely different parts of the electromagnetic spectrum -- observations that reinforced each other to make a solid case. Researchers are excited about the discovery. It means, they say, that scientists can study this object and begin to

  1. Light field morphing using 2D features.

    PubMed

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

    2005-01-01

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

  2. Internal Photoemission Spectroscopy of 2-D Materials

    NASA Astrophysics Data System (ADS)

    Nguyen, Nhan; Li, Mingda; Vishwanath, Suresh; Yan, Rusen; Xiao, Shudong; Xing, Huili; Cheng, Guangjun; Hight Walker, Angela; Zhang, Qin

    Recent research has shown the great benefits of using 2-D materials in the tunnel field-effect transistor (TFET), which is considered a promising candidate for the beyond-CMOS technology. The on-state current of TFET can be enhanced by engineering the band alignment of different 2D-2D or 2D-3D heterostructures. Here we present the internal photoemission spectroscopy (IPE) approach to determine the band alignments of various 2-D materials, in particular SnSe2 and WSe2, which have been proposed for new TFET designs. The metal-oxide-2-D semiconductor test structures are fabricated and characterized by IPE, where the band offsets from the 2-D semiconductor to the oxide conduction band minimum are determined by the threshold of the cube root of IPE yields as a function of photon energy. In particular, we find that SnSe2 has a larger electron affinity than most semiconductors and can be combined with other semiconductors to form near broken-gap heterojunctions with low barrier heights which can produce a higher on-state current. The details of data analysis of IPE and the results from Raman spectroscopy and spectroscopic ellipsometry measurements will also be presented and discussed.

  3. Black Holes

    NASA Astrophysics Data System (ADS)

    Luminet, Jean-Pierre

    1992-09-01

    Foreword to the French edition; Foreword to the English edition; Acknowledgements; Part I. Gravitation and Light: 1. First fruits; 2. Relativity; 3. Curved space-time; Part II. Exquisite Corpses: 4. Chronicle of the twilight years; 5. Ashes and diamonds; 6. Supernovae; 7. Pulsars; 8. Gravitation triumphant; Part III. Light Assassinated: 9. The far horizon; 10. Illuminations; 11. A descent into the maelstrom; 12. Map games; 13. The black hole machine; 14. The quantum black hole; Part IV. Light Regained: 15. Primordial black holes; 16. The zoo of X-ray stars; 17. Giant black holes; 18. Gravitational light; 19. The black hole Universe; Appendices; Bibliography; Name index; Subject index.

  4. Optical variation of black hole binary systems V616 Mon and Swift J1753.5-0127

    NASA Astrophysics Data System (ADS)

    Kocak, Dolunay; Yakut, Kadri

    2016-07-01

    Long- and short-term optical observations of X-ray binaries with black hole components, V616 Mon and Swift J1753.5-0127, obtained by using the 100cm telescope and 60cm Robotic telescope at the TÜBİTAK National Observatory (TUG). Photometric behaviors of the systems Swift J1753.5-0127 and V616 Mon are analyzed and compared with the earlier published results. Short-term observations of V616 Mon shows periodic variations.

  5. Mode Selection Rules for Two-Delay Systems: Dynamical Explanation for the Function of the Register Hole on the Clarinet

    NASA Astrophysics Data System (ADS)

    Takahashi, Kin'ya; Goya, Kana; Goya, Saya

    2014-12-01

    Generally, time-delay systems are regarded as multi-attractor systems. We investigate mode selection rules for two-delay systems considering which oscillation mode is first excited by the Hopf bifurcation with increasing a bifurcation parameter. In particular, we focus on the case that the strength of the short time delay α1 is lower than that of the long time delay α2. In a certain range of α1/α2 in which it is sufficiently small but still not negligible, the third-harmonic mode occupies a particular range of the ratio of the two delay times such that 2 < tR2/tR1 < 4, where tR1 and tR2 denote the short and long delay times, respectively. This is the key for understanding the function of the register hole on the clarinet, which is smaller in radius than the other tone holes, but works well to raise the pitch of first register notes in a wide range more than an octave by a twelfth (19 semitones), i.e., generating third harmonics, when opened. This is confirmed using a simple model of the clarinet with two delays: short and long time delays are regarded as delayed reflections caused by the register hole and the open end of the pipe, respectively. The working range of the register hole roughly corresponds to the particular range of the third-harmonic mode for two-delay systems (2 < tR2/tR1 < 4).

  6. Exploring Black Hole Dynamics

    NASA Astrophysics Data System (ADS)

    Chung, Hyeyoun

    2015-10-01

    This thesis explores the evolution of different types of black holes, and the ways in which black hole dynamics can be used to answer questions about other physical systems. We first investigate the differences in observable gravitational effects between a four-dimensional Randall-Sundrum (RS) braneworld universe compared to a universe without the extra dimension, by considering a black hole solution to the braneworld model that is localized on the brane. When the brane has a negative cosmological constant, then for a certain range of parameters for the black hole, the intersection of the black hole with the brane approximates a Banados-Teitelboim-Zanelli (BTZ) black hole on the brane with corrections that fall off exponentially outside the horizon. We compute the quasinormal modes of the braneworld black hole, and compare them to the known quasinormal modes of the three-dimensional BTZ black hole. We find that there are two distinct regions for the braneworld black hole solutions that are reflected in the dependence of the quasinormal modes on the black hole mass. The imaginary parts of the quasinormal modes display phenomenological similarities to the quasinormal modes of the three-dimensional BTZ black hole, indicating that nonlinear gravitational effects may not be enough to distinguish between a lower-dimensional theory and a theory derived from a higher-dimensional braneworld. Secondly, we consider the evolution of non-extremal black holes in N=4, d=2 supergravity, and investigate how such black holes might evolve over time if perturbed away from extremality. We study this problem in the probe limit by finding tunneling amplitudes for a Dirac field in a single-centered background, which gives the decay rates for the emission of charged probe black holes from the central black hole. We find that there is no minimum to the potential for the probe particles at a finite distance from the central black hole, so any probes that are emitted escape to infinity. If

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  8. Tunnelling from black holes and tunnelling into white holes

    NASA Astrophysics Data System (ADS)

    Chatterjee, Bhramar; Ghosh, A.; Mitra, P.

    2008-03-01

    Hawking radiation is nowadays being understood as tunnelling through black hole horizons. Here, the extension of the Hamilton-Jacobi approach to tunnelling for non-rotating and rotating black holes in different non-singular coordinate systems not only confirms this quantum emission from black holes but also reveals the new phenomenon of absorption into white holes by quantum mechanical tunnelling. The rôle of a boundary condition of total absorption or emission is also clarified.

  9. Gamma emission tomosynthesis based on an automated slant hole collimation system

    NASA Astrophysics Data System (ADS)

    Pellegrini, R.; Pani, R.; Cinti, M. N.; Longo, M.; Lo Meo, S.; Viviano, M.

    2015-03-01

    The imaging capabilities of radioisotope molecular imaging systems are limited by their ring geometry and by the object-to-detector distance, which impairs spatial resolution, efficiency and image quality. These detection capabilities could be enhanced by performing acquisitions with dedicated gamma cameras placed in close proximity to the object that has to be examined. The main aim of this work is to develop a compact camera suitable for detecting small and low-contrast lesions, with a higher detection efficiency than conventional SPECT, through a gamma emission tomosynthesis method. In this contribution a prototype of a new automated slant hole collimator, coupled to a small Field of View (FoV) gamma camera, is presented. The proposed device is able to acquire planar projection images at different angles without rotating around the patient body; these projection images are then three-dimensional reconstructed. Therefore, in order to perform the volumetric reconstruction of the studied object, the traditional Back Projection (BP) reconstruction is compared with the Shift And Add (SAA) method. In order to verify the effectiveness of the technique and to test the image reconstruction algorithms, a Monte Carlo simulation, based on the GEANT4 code, was implemented. The method was also validated by a set of experimental measurements. The discussed device is designed to work in patient proximity for detecting lesions placed at a distances ranged from 0 to 8 cm, thus allowing few millimeters planar resolutions and sagittal resolution of about 2 cm. The new collimation method implies high-resolution capabilities demonstrated by reconstructing the projection images through the BP and the SAA methods. The latter is simpler than BP and produces comparable spatial resolutions with respect to the traditional tomographic method, while preserving the image counts.

  10. Millimeter wave transmission spectroscopy of gated two-dimensional hole systems

    NASA Astrophysics Data System (ADS)

    Stone, K.; Du, R. R.; Manfra, M. J.; Pfeiffer, L. N.; West, K. W.

    2012-05-01

    We developed a differential transmission to study cyclotron resonance of GaAs/AlxGa1-xAs two-dimensional hole samples. The technique utilizes a modulated AuPd gate isolated by a Si3 N4 dielectric from the sample, which is irradiated opposite the gate by millimeter waves ranging from 2 to 40 GHz. This technique effectively removes the background signal and yields a hole effective mass of 0.41me with a cyclotron scattering time of ˜20 ps, consistent with the previous results using different techniques.

  11. Matrix models of 2d gravity

    SciTech Connect

    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.

  12. Matrix models of 2d gravity

    SciTech Connect

    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.

  13. 2-d Finite Element Code Postprocessor

    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

  14. Numerical Simulations and Experiments about Contamination Mechanism of Solid Immersion Lens System Concerning Hole and Geometries of Lens Holder

    NASA Astrophysics Data System (ADS)

    Choi, Moon-Ho; Yang, Tae-Man; Rhim, Yoon-Chul; Seo, Jeong-Kyo; Choi, In-Ho; Min, Byung-Hoon

    2008-07-01

    The air flow field around a conical type solid immersion lens (SIL) system is simulated numerically and confirmed with experiment using a micro-particle image velocimetry (PIV) system. It is found that the back-flow from the downstream of the SIL is a major candidate for the contamination of the SIL. Five modifications are proposed to suppress the particle conveying mechanism, the back-flow. Among these modifications a method using two flow-bypasses reduces the back-flow most effectively, which connects the top surface of the SIL system and two side-holes of the lens holder where the static pressure is the minimum.

  15. Chemical Approaches to 2D Materials.

    PubMed

    Samorì, Paolo; Palermo, Vincenzo; Feng, Xinliang

    2016-08-01

    Chemistry plays an ever-increasing role in the production, functionalization, processing and applications of graphene and other 2D materials. This special issue highlights a selection of enlightening chemical approaches to 2D materials, which nicely reflect the breadth of the field and convey the excitement of the individuals involved in it, who are trying to translate graphene and related materials from the laboratory into a real, high-impact technology. PMID:27478083

  16. Performance evaluation of a small CZT pixelated semiconductor gamma camera system with a newly designed stack-up parallel-hole collimator

    NASA Astrophysics Data System (ADS)

    Lee, Youngjin; Kim, Hee-Joung

    2015-09-01

    Gamma ray imaging techniques that use a cadmium zinc telluride (CZT) or cadmium telluride (CdTe) pixelated semiconductor detectors have rapidly gained popularity as a key tool for nuclear medicine research. By using a pinhole collimator with a pixelated semiconductor gamma camera system, better spatial resolution can be achieved. However, this improvement in spatial resolution is accomplished with a decrease in the sensitivity due to the small collimator hole diameter. Furthermore, few studies have been conducted for novel parallel-hole collimator geometric designs with pixelated semiconductor gamma camera systems. A gamma camera system which combines a CZT pixelated semiconductor detector with a newly designed stack-up parallel-hole collimator was developed and evaluated. The eValuator-2500 CZT pixelated semiconductor detector (eV product, Saxonburg, PA) was selected for the gamma camera system. This detector consisted of a row of four CZT crystals of 12.8 mm in length with 3 mm in thickness. The proposed parallel-hole collimator consists of two layers. The upper layer results in a fourfold increase in hole size compared to a matched square hole parallel-hole collimator with an equal hole and pixel size, while the lower layer also consisted of fourfold holes size and pretty acts as a matched square hole parallel-hole collimator. The overlap ratios of these collimators were 1:1, 1:2, 2:1, 1:5, and 5:1. These collimators were mounted on the eValuator-2500 CZT pixelated semiconductor detector. The basic performance of the imaging system was measured for a 57Co gamma source (122 keV). The measured averages of sensitivity and spatial resolution varied depending on the overlap ratios of the proposed parallel-hole collimator and source-to-collimator distances. One advantage of our system is the use of stacked collimators that can select the best combination of system sensitivity and spatial resolution. With low counts, we can select a high sensitivity collimator with a 1

  17. Extended 2D generalized dilaton gravity theories

    NASA Astrophysics Data System (ADS)

    de Mello, R. O.

    2008-09-01

    We show that an anomaly-free description of matter in (1+1) dimensions requires a deformation of the 2D relativity principle, which introduces a non-trivial centre in the 2D Poincaré algebra. Then we work out the reduced phase space of the anomaly-free 2D relativistic particle, in order to show that it lives in a noncommutative 2D Minkowski space. Moreover, we build a Gaussian wave packet to show that a Planck length is well defined in two dimensions. In order to provide a gravitational interpretation for this noncommutativity, we propose to extend the usual 2D generalized dilaton gravity models by a specific Maxwell component, which guages the extra symmetry associated with the centre of the 2D Poincaré algebra. In addition, we show that this extension is a high energy correction to the unextended dilaton theories that can affect the topology of spacetime. Further, we couple a test particle to the general extended dilaton models with the purpose of showing that they predict a noncommutativity in curved spacetime, which is locally described by a Moyal star product in the low energy limit. We also conjecture a probable generalization of this result, which provides strong evidence that the noncommutativity is described by a certain star product which is not of the Moyal type at high energies. Finally, we prove that the extended dilaton theories can be formulated as Poisson Sigma models based on a nonlinear deformation of the extended Poincaré algebra.

  18. Development of an AOI system for chips with a hole on backside based on a frame imager

    NASA Astrophysics Data System (ADS)

    Chen, Ming-Fu; Chou, Chih-Chung; Lien, Chun-Chien; Weng, Rui-Cian

    2016-01-01

    Defects exist for a few of IC chips during fabrication and packaging. The cost for follow-up processes can be reduced if chips with defect size of impacting chip quality can be inspected and removed during the earlier sorting process. Products will be more cost-effective and competitive. According to the inspecting requirements for microphone chips, developed AOI system has to detect the boundary flaws and hole-inside defects with size of greater than criteria from chips backside. Both the length and width of chip size are less than 5 mm and there's depth difference between the surface of chip backside and the hole-inside membrance. Thus image acquisition device is designed and implemented by an area scan imager and a telecentric lenses with a coaxial LED lighting module. Therefore we can ignore the image radiometric and geometric calibration, and keep off the shadow inside the rim of hole. An algorithm to detect defects and derive their size based on the edge pixels statistic distribution and binary chip edge image is selected. Developed AOI system then can meet the requirements of real-time defect inspection with high accuracy and performance. Frame opto-mechanical device has the spatial resolution of 5μm and FOV of 6.4 x 5.1 mm. And defect inspection can be completed within 150 ms for the chip size of 2.5 x 3.0 mm. The processes of image acquisition and defect inspection can be accomplished during the chip sorting process to satisfy the real-time online inspection. Inspected chips are placed in GO/NG trays in real-time according to their quality. From the verification results compared with the ones by microscope, the inspection accuracy is better than system requirements. The over kill rate is less than 0.3% and 3% for chip boundary flaws and hole-inside defects respectively. But it still can't be inspected correctly for the hole-inside defects of only one membrance breakage. In the future, we will improve the illumination and detecting algorithm to solve this

  19. An object-specific and dose-sparing scatter correction approach for a dedicated cone-beam breast CT system using a parallel-hole collimator

    NASA Astrophysics Data System (ADS)

    Yang, Kai; Burkett, George, Jr.; Boone, John M.

    2012-03-01

    X-ray scatter is a common cause of image artifacts for cone-beam CT systems due to the expanded field of view and degrades the quantitative accuracy of measured Hounsfield Units (HU). Due to the strong dependency of scatter on the object being scanned, it is crucial to measure the scatter signal for each object. We propose to use a beam pass array (BPA) composed of parallel-holes within a tungsten plate to measure scatter for a dedicated breast CT system. A complete study of the performance of the BPA was conducted. The goal of this study was to explore the feasibility of measuring and compensating for the scatter signal for each individual object. Different clinical study schemes were investigated, including a full rotation scan with BPA and discrete projections acquired with BPA followed by interpolation for full rotation. Different sized cylindrical phantoms and a breast shaped polyethylene phantom were used to test for the robustness of the proposed method. Physically measured scatter signals were converted into scatter to primary ratios (SPRs) at discrete locations through the projection image. A complete noise-free 2D SPR was generated from these discrete measurements. SPR results were compared to Monte Carlo simulation results and scatter corrected CT images were quantitatively evaluated for "cupping" artifact. With the proposed method, a reduction of up to 47 HU of "cupping" was demonstrated. In conclusion, the proposed BPA method demonstrated effective and accurate objectspecific scatter correction with the main advantage of dose-sparing compared to beam stop array (BSA) approaches.

  20. Evolution of the CYP2D gene cluster in humans and four non-human primates.

    PubMed

    Yasukochi, Yoshiki; Satta, Yoko

    2011-01-01

    The human cytochrome P450 2D6 (CYP2D6) is a primary enzyme involved in the metabolism of about 25% of commonly used therapeutic drugs. CYP2D6 belongs to the CYP2D subfamily, a gene cluster located on chromosome 22, which comprises the CYP2D6 gene and pseudogenes CYP2D7P and CYP2D8P. Although the chemical and physiological properties of CYP2D6 have been extensively studied, there has been no study to date on molecular evolution of the CYP2D subfamily in the human genome. Such knowledge could greatly contribute to the understanding of drug metabolism in humans because it makes us to know when and how the current metabolic system has been constructed. The knowledge moreover can be useful to find differences in exogenous substrates in a particular metabolism between human and other animals such as experimental animals. Here, we conducted a preliminary study to investigate the evolution and gene organization of the CYP2D subfamily, focused on humans and four non-human primates (chimpanzees, orangutans, rhesus monkeys, and common marmosets). Our results indicate that CYP2D7P has been duplicated from CYP2D6 before the divergence between humans and great apes, whereas CYP2D6 and CYP2D8P have been already present in the stem lineages of New World monkeys and Catarrhini. Furthermore, the origin of the CYP2D subfamily in the human genome can be traced back to before the divergence between amniotes and amphibians. Our analyses also show that reported chimeric sequences of the CYP2D6 and CYP2D7 genes in the chimpanzee genome appear to be exchanged in its genome database. PMID:21670550

  1. Slim-hole Measurement While Drilling (MWD) system for underbalanced drilling

    SciTech Connect

    Harrison, W.H.; Harrison, J.D.; Rubin, L.A.

    1995-08-01

    The objective of this program is to make commercially available, wireless Measurement-while-drilling tools to reliably operate in air, air-mist, air-foam, and other unbalanced drilling environments during oil and gas directional drilling operations in conjunction with down-hole motors or other assemblies. Progress is described.

  2. Spin splitting in 2D monochalcogenide semiconductors

    PubMed Central

    Do, Dat T.; Mahanti, Subhendra D.; Lai, Chih Wei

    2015-01-01

    We report ab initio calculations of the spin splitting of the uppermost valence band (UVB) and the lowermost conduction band (LCB) in bulk and atomically thin GaS, GaSe, GaTe, and InSe. These layered monochalcogenides appear in four major polytypes depending on the stacking order, except for the monoclinic GaTe. Bulk and few-layer ε-and γ -type, and odd-number β-type GaS, GaSe, and InSe crystals are noncentrosymmetric. The spin splittings of the UVB and the LCB near the Γ-point in the Brillouin zone are finite, but still smaller than those in a zinc-blende semiconductor such as GaAs. On the other hand, the spin splitting is zero in centrosymmetric bulk and even-number few-layer β-type GaS, GaSe, and InSe, owing to the constraint of spatial inversion symmetry. By contrast, GaTe exhibits zero spin splitting because it is centrosymmetric down to a single layer. In these monochalcogenide semiconductors, the separation of the non-degenerate conduction and valence bands from adjacent bands results in the suppression of Elliot-Yafet spin relaxation mechanism. Therefore, the electron- and hole-spin relaxation times in these systems with zero or minimal spin splittings are expected to exceed those in GaAs when the D’yakonov-Perel’ spin relaxation mechanism is also suppressed. PMID:26596907

  3. Spin splitting in 2D monochalcogenide semiconductors

    NASA Astrophysics Data System (ADS)

    Do, Dat T.; Mahanti, Subhendra D.; Lai, Chih Wei

    2015-11-01

    We report ab initio calculations of the spin splitting of the uppermost valence band (UVB) and the lowermost conduction band (LCB) in bulk and atomically thin GaS, GaSe, GaTe, and InSe. These layered monochalcogenides appear in four major polytypes depending on the stacking order, except for the monoclinic GaTe. Bulk and few-layer ε-and γ -type, and odd-number β-type GaS, GaSe, and InSe crystals are noncentrosymmetric. The spin splittings of the UVB and the LCB near the Γ-point in the Brillouin zone are finite, but still smaller than those in a zinc-blende semiconductor such as GaAs. On the other hand, the spin splitting is zero in centrosymmetric bulk and even-number few-layer β-type GaS, GaSe, and InSe, owing to the constraint of spatial inversion symmetry. By contrast, GaTe exhibits zero spin splitting because it is centrosymmetric down to a single layer. In these monochalcogenide semiconductors, the separation of the non-degenerate conduction and valence bands from adjacent bands results in the suppression of Elliot-Yafet spin relaxation mechanism. Therefore, the electron- and hole-spin relaxation times in these systems with zero or minimal spin splittings are expected to exceed those in GaAs when the D’yakonov-Perel’ spin relaxation mechanism is also suppressed.

  4. NKG2D-NKG2D Ligand Interaction Inhibits the Outgrowth of Naturally Arising Low-Grade B Cell Lymphoma In Vivo.

    PubMed

    Raju, Saravanan; Kretzmer, Lena Z; Koues, Olivia I; Payton, Jacqueline E; Oltz, Eugene M; Cashen, Amanda; Polic, Bojan; Schreiber, Robert D; Shaw, Andrey S; Markiewicz, Mary A

    2016-06-01

    It is now clear that recognition of nascent tumors by the immune system is critical for survival of the host against cancer. During cancer immunoediting, the ability of the tumor to escape immune recognition is important for tumor development. The immune system recognizes tumors via the presence of classical Ags and also by conserved innate mechanisms. One of these mechanisms is the NKG2D receptor that recognizes ligands whose expression is induced by cell transformation. In this study, we show that in NKG2D receptor-deficient mice, increasing numbers of B cells begin to express NKG2D ligands as they age. Their absence in wild-type mice suggests that these cells are normally cleared by NKG2D-expressing cells. NKG2D-deficient mice and mice constitutively expressing NKG2D ligands had increased incidence of B cell tumors, confirming that the inability to clear NKG2D ligand-expressing cells was important in tumor suppression and that NKG2D ligand expression is a marker of nascent tumors. Supporting a role for NKG2D ligand expression in controlling the progression of early-stage B cell lymphomas in humans, we found higher expression of a microRNA that inhibits human NKG2D ligand expression in tumor cells from high-grade compared with low-grade follicular lymphoma patients. PMID:27183590

  5. Real-time 2-D temperature imaging using ultrasound.

    PubMed

    Liu, Dalong; Ebbini, Emad S

    2010-01-01

    We have previously introduced methods for noninvasive estimation of temperature change using diagnostic ultrasound. The basic principle was validated both in vitro and in vivo by several groups worldwide. Some limitations remain, however, that have prevented these methods from being adopted in monitoring and guidance of minimally invasive thermal therapies, e.g., RF ablation and high-intensity-focused ultrasound (HIFU). In this letter, we present first results from a real-time system for 2-D imaging of temperature change using pulse-echo ultrasound. The front end of the system is a commercially available scanner equipped with a research interface, which allows the control of imaging sequence and access to the RF data in real time. A high-frame-rate 2-D RF acquisition mode, M2D, is used to capture the transients of tissue motion/deformations in response to pulsed HIFU. The M2D RF data is streamlined to the back end of the system, where a 2-D temperature imaging algorithm based on speckle tracking is implemented on a graphics processing unit. The real-time images of temperature change are computed on the same spatial and temporal grid of the M2D RF data, i.e., no decimation. Verification of the algorithm was performed by monitoring localized HIFU-induced heating of a tissue-mimicking elastography phantom. These results clearly demonstrate the repeatability and sensitivity of the algorithm. Furthermore, we present in vitro results demonstrating the possible use of this algorithm for imaging changes in tissue parameters due to HIFU-induced lesions. These results clearly demonstrate the value of the real-time data streaming and processing in monitoring, and guidance of minimally invasive thermotherapy. PMID:19884075

  6. Probing the excited subband dispersion of holes confined to GaAs wide quantum wells

    NASA Astrophysics Data System (ADS)

    Jo, Insun; Liu, Yang; Deng, H.; Shayegan, M.; Pfeiffer, L. N.; West, K. W.; Baldwin, K. W.; Winkler, R.

    Owing to the strong spin-orbit coupling and their large effective mass, the two-dimensional (2D) holes in modulation-doped GaAs quantum wells provide a fertile test bed to study the rich physics of low-dimensional systems. In a wide quantum well, even at moderate 2D densities, the holes start to occupy the excited subband, a subband whose dispersion is very unusual and has a non-monotonic dependence on the wave vector. Here, we study a 2D hole system confined to a 40-nm-thick (001) GaAs quantum well and demonstrate that, via the application of both front and back gates, the density can be tuned in a wide range, between ~1 and 2 ×1011 cm-2. Using Fourier analysis of the low-field Shubnikov-de Haas oscillations, we investigate the population of holes and the spin-orbit interaction induced spin-splitting in different subbands. We discuss the results in light of self-consistent quantum calculations of magneto-oscillations. Work support by the DOE BES (DE-FG02-00-ER45841), the NSF (Grants DMR-1305691 and MRSEC DMR-1420541), the Gordon and Betty Moore Foundation (Grant GBMF4420), and Keck Foundation for experiments, and the NSF Grant DMR-1310199 for calculations.

  7. Mean flow and anisotropic cascades in decaying 2D turbulence

    NASA Astrophysics Data System (ADS)

    Liu, Chien-Chia; Cerbus, Rory; Gioia, Gustavo; Chakraborty, Pinaki

    2015-11-01

    Many large-scale atmospheric and oceanic flows are decaying 2D turbulent flows embedded in a non-uniform mean flow. Despite its importance for large-scale weather systems, the affect of non-uniform mean flows on decaying 2D turbulence remains unknown. In the absence of mean flow it is well known that decaying 2D turbulent flows exhibit the enstrophy cascade. More generally, for any 2D turbulent flow, all computational, experimental and field data amassed to date indicate that the spectrum of longitudinal and transverse velocity fluctuations correspond to the same cascade, signifying isotropy of cascades. Here we report experiments on decaying 2D turbulence in soap films with a non-uniform mean flow. We find that the flow transitions from the usual isotropic enstrophy cascade to a series of unusual and, to our knowledge, never before observed or predicted, anisotropic cascades where the longitudinal and transverse spectra are mutually independent. We discuss implications of our results for decaying geophysical turbulence.

  8. Quantum process tomography by 2D fluorescence spectroscopy

    SciTech Connect

    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 Γ 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.

  9. Evaluation of 2D ceramic matrix composites in aeroconvective environments

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  10. Radiative heat transfer in 2D Dirac materials

    DOE PAGESBeta

    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.

  11. Nomenclature for human CYP2D6 alleles.

    PubMed

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

    1996-06-01

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

  12. 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.

  13. Performance evaluation of high-resolution square parallel-hole collimators with a CZT room temperature pixelated semiconductor SPECT system: a Monte Carlo simulation study

    NASA Astrophysics Data System (ADS)

    Lee, Y.; Kang, W.

    2015-07-01

    The pixelated semiconductor based on cadmium zinc telluride (CZT) is a promising imaging device that provides many benefits compared with conventional scintillation detectors. By using a high-resolution square parallel-hole collimator with a pixelated semiconductor detector, we were able to improve both sensitivity and spatial resolution. Here, we present a simulation of a CZT pixleated semiconductor single-photon emission computed tomography (SPECT) system with a high-resolution square parallel-hole collimator using various geometric designs of 0.5, 1.0, 1.5, and 2.0 mm X-axis hole size. We performed a simulation study of the eValuator-2500 (eV Microelectronics Inc., Saxonburg, PA, U.S.A.) CZT pixelated semiconductor detector using a Geant4 Application for Tomographic Emission (GATE). To evaluate the performances of these systems, the sensitivity and spatial resolution was evaluated. Moreover, to evaluate the overall performance of the imaging system, a hot-rod phantom was designed. Our results showed that the average sensitivity of the 2.0 mm collimator X-axis hole size was 1.34, 1.95, and 3.92 times higher than that of the 1.5, 1.0, and 0.5 mm collimator X-axis hole size, respectively. Also, the average spatial resolution of the 0.5 mm collimator X-axis hole size was 28.69, 44.65, and 55.73% better than that of the 1.0, 1.5, and 2.0 mm collimator X-axis hole size, respectively. We discuss the high-resolution square parallel-hole collimator of various collimator geometric designs and our evaluations. In conclusion, we have successfully designed a high-resolution square parallel-hole collimator with a CZT pixelated semiconductor SPECT system.

  14. 2d PDE Linear Symmetric Matrix Solver

    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

  15. 2d PDE Linear Asymmetric Matrix Solver

    1983-10-01

    ILUCG2 (Incomplete LU factorized Conjugate Gradient algorithm for 2d problems) was developed to solve a linear asymmetric matrix system arising from a 9-point discretization of two-dimensional elliptic and parabolic partial differential equations found in plasma physics applications, such as plasma diffusion, equilibria, and phase space transport (Fokker-Planck equation) problems. These equations share the common feature of being stiff and requiring implicit solution techniques. When these parabolic or elliptic PDE''s are discretized with finite-difference or finite-elementmore » methods, the resulting matrix system is frequently of block-tridiagonal form. To use ILUCG2, 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. A generalization of the incomplete Cholesky conjugate gradient algorithm is used to solve the 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 problems having a symmetric matrix ICCG2 should be used since it runs up to four times faster and uses approximately 30% less storage. 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

  16. Thermopower of Interacting GaAs Bilayer Hole Systems in the Reentrant Insulating Phase Near ν=1

    NASA Astrophysics Data System (ADS)

    Faniel, S.; Tutuc, E.; Poortere, E. P.; Gustin, C.; Vlad, A.; Melinte, S.; Shayegan, M.; Bayot, V.

    2005-02-01

    We report thermopower measurements of interacting GaAs bilayer hole systems. When the carrier densities in the two layers are equal, these systems exhibit a reentrant insulating phase near the quantum Hall state at total filling factor ν=1. Our data show that, as the temperature is decreased, the thermopower diverges in the insulating phase. This behavior indicates the opening of an energy gap at low temperature, consistent with the formation of a pinned Wigner solid. We extract an energy gap and a Wigner solid melting phase diagram.

  17. Thermopower of interacting GaAs bilayer hole systems in the reentrant insulating phase near nu=1.

    PubMed

    Faniel, S; Tutuc, E; De Poortere, E P; Gustin, C; Vlad, A; Melinte, S; Shayegan, M; Bayot, V

    2005-02-01

    We report thermopower measurements of interacting GaAs bilayer hole systems. When the carrier densities in the two layers are equal, these systems exhibit a reentrant insulating phase near the quantum Hall state at total filling factor nu=1. Our data show that, as the temperature is decreased, the thermopower diverges in the insulating phase. This behavior indicates the opening of an energy gap at low temperature, consistent with the formation of a pinned Wigner solid. We extract an energy gap and a Wigner solid melting phase diagram. PMID:15783582

  18. Design optimization of a small-animal SPECT system using LGSO continuous crystals and micro parallel-hole collimators

    NASA Astrophysics Data System (ADS)

    Kim, Joong Hyun; Ito, Mikiko; Kim, Soo Mee; Hong, Seong Jong; Lee, Jae Sung

    2015-07-01

    A small-animal single photon emission computed tomography (SPECT) system having compact size and low cost was designed using monolithic LGSO scintillation crystals and micro parallel-hole collimators through Monte Carlo simulations. A spatial resolution of ~1 mm and a sensitivity of ~100 cps/MBq were achieved with a four-head SPECT system. A hot rod with a diameter of 1.0 mm was resolved in the SPECT image of the ultra-micro hot spot phantom. Using a thin monolithic crystal and micro collimator, we achieved high spatial resolution and high sensitivity.

  19. Einstein-Maxwell system in 3+1 form and initial data for multiple charged black holes

    SciTech Connect

    Alcubierre, Miguel; Degollado, Juan Carlos; Salgado, Marcelo

    2009-11-15

    We consider the Einstein-Maxwell system as a Cauchy initial value problem taking the electric and magnetic fields as independent variables. Maxwell's equations in curved spacetimes are derived in detail using a 3+1 formalism and their hyperbolic properties are analyzed, showing that the resulting system is symmetric hyperbolic. We also focus on the problem of finding initial data for multiple charged black holes assuming time-symmetric initial data and using a puncturelike method to solve the Hamiltonian and the Gauss constraints. We study the behavior of the resulting initial data families, and show that previous results in this direction can be obtained as particular cases of our approach.

  20. III-V semiconductor Quantum Well systems: Physics of Gallium Arsenide two-dimensional hole systems and engineering of mid-infrared Quantum Cascade lasers

    NASA Astrophysics Data System (ADS)

    Chiu, YenTing

    This dissertation examines two types of III-V semiconductor quantum well systems: two-dimensional holes in GaAs, and mid-infrared Quantum Cascade lasers. GaAs holes have a much reduced hyperfine interaction with the nuclei due to the p-like orbital, resulting in a longer hole spin coherence time comparing to the electron spin coherence time. Therefore, holes' spins are promising candidates for quantum computing qubits, but the effective mass and the Lande g-factor, whose product determines the spin-susceptibility of holes, are not well known. In this thesis, we measure the effective hole mass through analyzing the temperature dependence of Shubnikov-de Haas oscillations in a relatively strong interacting two-dimensional hole systems confined to a 20 nm-wide, (311)A GaAs quantum well. The holes in this system occupy two nearly-degenerate spin subbands whose effective mass we measure to be ˜ 0.2 me. We then apply a sufficiently strong parallel magnetic field to fully depopulate one of the spin subbands, and the spin susceptibility of the two-dimensional hole system is deduced from the depopulation field. We also confine holes in closely spaced bilayer GaAs quantum wells to study the interlayer tunneling spectrum as a function of interlayer bias and in-plane magnetic field, in hope of probing the hole's Fermi contour. Quantum Cascade lasers are one of the major mid-infrared light sources well suited for applications in health and environmental sensing. One of the important factors that affect Quantum Cascade laser performance is the quality of the interfaces between the epitaxial layers. What has long been neglected is that interface roughness causes intersubband scattering, and thus affecting the relation between the lifetimes of the upper and lower laser states, which determines if population inversion is possible. We first utilize strategically added interface roughness in the laser design to engineer the intersubband scattering lifetimes. We further

  1. Discovery of X-Ray Emission from the First Be/Black Hole System

    NASA Astrophysics Data System (ADS)

    Munar-Adrover, P.; Paredes, J. M.; Ribó, M.; Iwasawa, K.; Zabalza, V.; Casares, J.

    2014-05-01

    MWC 656 (=HD 215227) was recently discovered to be the first binary system composed of a Be star and a black hole (BH). We observed it with XMM-Newton, and detected a faint X-ray source compatible with the position of the optical star, thus proving it to be the first Be/BH X-ray binary. The spectrum analysis requires a model fit with two components, a blackbody plus a power law, with k_BT = 0.07^{+0.04}_{-0.03} keV and a photon index Γ = 1.0 ± 0.8, respectively. The non-thermal component dominates above sime0.8 keV. The obtained total flux is F(0.3-5.5\\, keV) = (4.6^{+1.3}_{-1.1})\\times 10^{-14} erg cm-2 s-1. At a distance of 2.6 ± 0.6 kpc the total flux translates into a luminosity L X = (3.7 ± 1.7) × 1031 erg s-1. Considering the estimated range of BH masses to be 3.8-6.9 M ⊙, this luminosity represents (6.7 ± 4.4) × 10-8 L Edd, which is typical of stellar-mass BHs in quiescence. We discuss the origin of the two spectral components: the thermal component is associated with the hot wind of the Be star, whereas the power-law component is associated with emission from the vicinity of the BH. We also find that the position of MWC 656 in the radio versus X-ray luminosity diagram may be consistent with the radio/X-ray correlation observed in BH low-mass X-ray binaries. This suggests that this correlation might also be valid for BH high-mass X-ray binaries (HMXBs) with X-ray luminosities down to ~10-8 L Edd. MWC 656 will allow the accretion processes and the accretion/ejection coupling at very low luminosities for BH HMXBs to be studied.

  2. DISCOVERY OF X-RAY EMISSION FROM THE FIRST Be/BLACK HOLE SYSTEM

    SciTech Connect

    Munar-Adrover, P.; Paredes, J. M.; Ribó, M.; Iwasawa, K.; Zabalza, V.; Casares, J.

    2014-05-10

    MWC 656 (=HD 215227) was recently discovered to be the first binary system composed of a Be star and a black hole (BH). We observed it with XMM-Newton, and detected a faint X-ray source compatible with the position of the optical star, thus proving it to be the first Be/BH X-ray binary. The spectrum analysis requires a model fit with two components, a blackbody plus a power law, with k{sub B}T=0.07{sub −0.03}{sup +0.04} keV and a photon index Γ = 1.0 ± 0.8, respectively. The non-thermal component dominates above ≅0.8 keV. The obtained total flux is F(0.3-5.5 keV)=(4.6{sub −1.1}{sup +1.3})×10{sup −14} erg cm{sup –2} s{sup –1}. At a distance of 2.6 ± 0.6 kpc the total flux translates into a luminosity L {sub X} = (3.7 ± 1.7) × 10{sup 31} erg s{sup –1}. Considering the estimated range of BH masses to be 3.8-6.9 M {sub ☉}, this luminosity represents (6.7 ± 4.4) × 10{sup –8} L {sub Edd}, which is typical of stellar-mass BHs in quiescence. We discuss the origin of the two spectral components: the thermal component is associated with the hot wind of the Be star, whereas the power-law component is associated with emission from the vicinity of the BH. We also find that the position of MWC 656 in the radio versus X-ray luminosity diagram may be consistent with the radio/X-ray correlation observed in BH low-mass X-ray binaries. This suggests that this correlation might also be valid for BH high-mass X-ray binaries (HMXBs) with X-ray luminosities down to ∼10{sup –8} L {sub Edd}. MWC 656 will allow the accretion processes and the accretion/ejection coupling at very low luminosities for BH HMXBs to be studied.

  3. A Monte Carlo simulation study of the feasibility of a high resolution parallel-hole collimator with a CdTe pixelated semiconductor SPECT system

    NASA Astrophysics Data System (ADS)

    Lee, Y.-J.; Park, S.-J.; Lee, S.-W.; Kim, D.-H.; Kim, Y.-S.; Jo, B.-D.; Kim, H.-J.

    2013-03-01

    It is recommended that a pixelated parallel-hole collimator in which the hole and pixel sizes are equal be used to improve the sensitivity and spatial resolution when using a small pixel size and a single-photon emission computed tomography (SPECT) system with pixelated semiconductor detector materials (e.g., CdTe and CZT). However, some significant problems arise in the manufacturing of a pixelated parallel-hole collimator. Therefore, we sought to simulate a pixelated semiconductor SPECT system with various collimator geometric designs. The purpose of this study was to compare the quality of images generated with a pixelated semiconductor SPECT system simulated with pixelated parallel-hole collimators of various geometric designs. The sensitivity and spatial resolution of the various collimator geometric designs with varying septal heights and hole sizes were measured. Moreover, to evaluate the overall performance of the imaging system, a hot-rod phantom was designed using a Monte Carlo simulation. According to the results, the average sensitivity using a 15 mm septal height was 1.80, 2.87, and 4.16 times higher than that obtained with septal heights of 20, 25, and 30 mm, respectively. Also, the average spatial resolution using the 30 mm septal height was 44.33, 22.08, and 9.26% better than that attained with 15, 20, and 25 mm septal heights, respectively. When the results acquired with 0.3 and 0.6 mm hole sizes were compared, the average sensitivity with the 0.6 mm hole size was 3.97 times higher than that obtained with the 0.3 mm hole size, and the average spatial resolution with the 0.3 mm hole size was 45.76% better than that with the 0.6 mm hole size. We have presented the pixelated parallel-hole collimators of various collimator geometric designs and evaluations. Our results showed that the effect of various collimator geometric designs can be investigated by Monte Carlo simulation so as to evaluate the feasibility of a high resolution parallel-hole

  4. Application of high resolution 2D/3D spectral induced polarization (SIP) in metalliferous ore exploration

    NASA Astrophysics Data System (ADS)

    Chen, R.; Zhao, X.; Yao, H.; He, X.; Zeng, P.; Chang, F.; Yang, Y.; Zhang, X.; Xi, X.; He, L.

    2015-12-01

    Induced polarization (IP) is a powerful tool in metalliferous ore exploration. However, there are many sources, such as clay and graphite, which can generate IP anomaly. Spectral induced polarization (SIP) measures IP response on a wide frequency range. This method provides a way to discriminate IP response generated by metalliferous ore or other objects. The best way to explore metalliferous ore is 3D SIP exploration. However, if we consider the exploration cost and efficiency, we can use SIP profiling to find an anomaly, and then use 2D/3D SIP sounding to characterize the anomaly. Based on above idea, we used a large-scale distributed SIP measurement system which can realize 800 sounding sites in one direction at the same time. This system can be used for SIP profiling, 2D/3D SIP sounding with high efficiency, high resolution, and large depth of investigation (> 1000 m). Qiushuwan copper - molybdenum deposit is located in Nanyang city, Henan province, China. It is only a middle-size deposit although over 100 holes were drilled and over 40 years of exploration were spent because of very complex geological setting. We made SIP measurement over 100 rock and ore samples to discriminate IP responses of ore and rock containing graphite. Then we carried out 7 lines of 2D SIP exploration with the depth of investigation great than 1000 m. The minimum electode spacing for potential difference is only 20 m. And we increase the spacing of current electodes at linear scale. This acquisition setting ensures high density data acquired and high quality data acquisition. Modeling and inversion result proves that we can get underground information with high resolution by our method. Our result shows that there exists a strong SIP response related to ore body in depth > 300 m. Pseudo-3D inversion of five 2D SIP sounding lines shows the location and size of IP anomaly. The new drillings based our result found a big copper-molybdenum ore body in new position with depth > 300 m and

  5. Optical modulators with 2D layered materials

    NASA Astrophysics Data System (ADS)

    Sun, Zhipei; Martinez, Amos; Wang, Feng

    2016-04-01

    Light modulation is an essential operation in photonics and optoelectronics. With existing and emerging technologies increasingly demanding compact, efficient, fast and broadband optical modulators, high-performance light modulation solutions are becoming indispensable. The recent realization that 2D layered materials could modulate light with superior performance has prompted intense research and significant advances, paving the way for realistic applications. In this Review, we cover the state of the art of optical modulators based on 2D materials, including graphene, transition metal dichalcogenides and black phosphorus. We discuss recent advances employing hybrid structures, such as 2D heterostructures, plasmonic structures, and silicon and fibre integrated structures. We also take a look at the future perspectives and discuss the potential of yet relatively unexplored mechanisms, such as magneto-optic and acousto-optic modulation.

  6. Large Area Synthesis of 2D Materials

    NASA Astrophysics Data System (ADS)

    Vogel, Eric

    Transition metal dichalcogenides (TMDs) have generated significant interest for numerous applications including sensors, flexible electronics, heterostructures and optoelectronics due to their interesting, thickness-dependent properties. Despite recent progress, the synthesis of high-quality and highly uniform TMDs on a large scale is still a challenge. In this talk, synthesis routes for WSe2 and MoS2 that achieve monolayer thickness uniformity across large area substrates with electrical properties equivalent to geological crystals will be described. Controlled doping of 2D semiconductors is also critically required. However, methods established for conventional semiconductors, such as ion implantation, are not easily applicable to 2D materials because of their atomically thin structure. Redox-active molecular dopants will be demonstrated which provide large changes in carrier density and workfunction through the choice of dopant, treatment time, and the solution concentration. Finally, several applications of these large-area, uniform 2D materials will be described including heterostructures, biosensors and strain sensors.

  7. 2D-Crystal-Based Functional Inks.

    PubMed

    Bonaccorso, Francesco; Bartolotta, Antonino; Coleman, Jonathan N; Backes, Claudia

    2016-08-01

    The possibility to produce and process graphene, related 2D crystals, and heterostructures in the liquid phase makes them promising materials for an ever-growing class of applications as composite materials, sensors, in flexible optoelectronics, and energy storage and conversion. In particular, the ability to formulate functional inks with on-demand rheological and morphological properties, i.e., lateral size and thickness of the dispersed 2D crystals, is a step forward toward the development of industrial-scale, reliable, inexpensive printing/coating processes, a boost for the full exploitation of such nanomaterials. Here, the exfoliation strategies of graphite and other layered crystals are reviewed, along with the advances in the sorting of lateral size and thickness of the exfoliated sheets together with the formulation of functional inks and the current development of printing/coating processes of interest for the realization of 2D-crystal-based devices. PMID:27273554

  8. Spin-Spin Effects in Models of Binary Black Hole Systems

    NASA Astrophysics Data System (ADS)

    Hawley, Scott; Matzner, Richard; Thompson, Lindsey

    2012-03-01

    We have implemented a parallel multigrid solver, to solve the initial data problem for 3 + 1 General Relativity. This involves solution of elliptic equations derived from the Hamiltonian and the momentum constraints. We use the conformal transverse-traceless method of York and collaborators which consists of a conformal decomposition with a scalar that adjusts the metric, and a vector potential that adjusts the longitudinal components of the extrinsic curvature. The constraint equations are then solved for these quantities such that the complete solution fully satisfies the constraints. We apply this technique to compare with theoretical expectations for the spin-orientation- and separation-dependence in the case of spinning interacting (but not orbiting) black holes. We write out a formula for the effect of the spin-spin interaction which includes a result of Wald as well as additional effect due to the rotation of the mass quadrupole moment of a spinning black hole.

  9. Klassifikation von Standardebenen in der 2D-Echokardiographie mittels 2D-3D-Bildregistrierung

    NASA Astrophysics Data System (ADS)

    Bergmeir, Christoph; Subramanian, Navneeth

    Zum Zweck der Entwicklung eines Systems, das einen unerfahrenen Anwender von Ultraschall (US) zur Aufnahme relevanter anatomischer Strukturen leitet, untersuchen wir die Machbarkeit von 2D-US zu 3D-CT Registrierung. Wir verwenden US-Aufnahmen von Standardebenen des Herzens, welche zu einem 3D-CT-Modell registriert werden. Unser Algorithmus unterzieht sowohl die US-Bilder als auch den CT-Datensatz Vorverarbeitungsschritten, welche die Daten durch Segmentierung auf wesentliche Informationen in Form von Labein für Muskel und Blut reduzieren. Anschließend werden diese Label zur Registrierung mittels der Match-Cardinality-Metrik genutzt. Durch mehrmaliges Registrieren mit verschiedenen Initialisierungen ermitteln wir die im US-Bild sichtbare Standardebene. Wir evaluierten die Methode auf sieben US-Bildern von Standardebenen. Fünf davon wurden korrekt zugeordnet.

  10. Stability of spherically symmetric, charged black holes and multipole moments for stationary systems

    SciTech Connect

    Gursel, H.Y.

    1983-01-01

    This dissertation is written in two parts. Part I deals with the question of stability of a spherically symmetric, charged black hole against scalar, electromagnetic, and gravitational perturbations. It consists of two papers written in collaboration with Igor D. Novikov, Vernon D. Sandberg and A.A. Starobinsky. In these papers the dynamical evolution of these perturbations on the interior of a Reissner-Nordstrom black hole is described. The instability of the hole's Cauchy horizon is discussed in detail in terms of the energy densities of the test fields as measured by a freely falling observer approaching the Cauchy horizon. It is concluded that the Cauchy horizon of the analytically extended Reissner-Nordstrom solution is highly unstable and not a physical feature of a realistic gravitational collapse. Part II of this dissertation addresses two problems closely connected with multipole structure of stationary, asymptotically flat spacetimes. It consists of two papers written in collaboration with Kip S. Thorne. The first one shows the equivalence of the moments defined by Kip S. Thorne and the moments defined by Robert Geroch and Richard Hansen. The second proves a conjecture by Kip S. Thorne: In the limit of ''slow'' motion, general relativistic gravity produces no changes whatsoever in the classical Euler equations of rigid body motion. This conjecture is proved by giving an algorithm for generating rigidly rotating solutions of Einstein's equation from nonrotating, static solutions.

  11. Inkjet printing of 2D layered materials.

    PubMed

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

    2014-11-10

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

  12. Evaluation of separation properties of a modified strong cation exchange material named MEX and its application in 2D-MEX × C18 system to separate peptides from scorpion venom.

    PubMed

    Chen, Bo; Xu, Junyan; Fu, Qing; Dong, Xuefang; Guo, Zhimou; Jin, Yu; Liang, Xinmiao

    2015-07-01

    Peptides from scorpion venom represent one of the most promising drug sources for drug discovery for some specific diseases. Current challenges in their separation include high complexity, high homologies and the huge range of peptides. In this paper, a modified strong cation exchange material, named MEX, was utilised for the two-dimensional separation of peptides from complex scorpion venom. The silica-based MEX column was bonded with two functional groups; benzenesulfonic acid and cyanopropyl. To better understand its separation mechanisms, seven standard peptides with different properties were employed in an evaluation study, the results of which showed that two interactions were involved in the MEX column: electrostatic interactions based on benzenesulfonic acid groups dominated the separation of peptides; weak hydrophobic interactions introduced by cyanopropyl groups increased the column's selectivity for peptides with the same charge. This characteristic allowed the MEX column to overcome some of the drawbacks of traditional strong cation exchange (SCX) columns. Furthermore, the study showed the great effects of the acetonitrile (ACN) content, the sodium perchlorate (NaClO4) concentration and the buffer pH in the mobile phase on the peptides' retention and separation selectivity on the MEX column. Subsequently, the MEX column was combined with a C18 column to establish an off-line 2D-MEX × C18 system to separate peptides from scorpion Buthus martensi Karsch (BmK) venom. Due to complementary separation mechanisms in each dimension, a high orthogonality of 47.62% was achieved. Moreover, a good loading capacity, excellent stability and repeatability were exhibited by the MEX column, which are beneficial for its use in future preparation experiments. Therefore, the MEX column could be an alternative to the traditional SCX columns for the separation of peptides from scorpion venom. PMID:25996445

  13. A scintillating gas detector for 2D dose measurements in clinical carbon beams.

    PubMed

    Seravalli, E; de Boer, M; Geurink, F; Huizenga, J; Kreuger, R; Schippers, J M; van Eijk, C W E; Voss, B

    2008-09-01

    A two-dimensional position sensitive dosimetry system based on a scintillating gas detector has been developed for pre-treatment verification of dose distributions in hadron therapy. The dosimetry system consists of a chamber filled with an Ar/CF4 scintillating gas mixture, inside which two cascaded gas electron multipliers (GEMs) are mounted. A GEM is a thin kapton foil with copper cladding structured with a regular pattern of sub-mm holes. The primary electrons, created in the detector's sensitive volume by the incoming beam, drift in an electric field towards the GEMs and undergo gas multiplication in the GEM holes. During this process, photons are emitted by the excited Ar/CF4 gas molecules and detected by a mirror-lens-CCD camera system. Since the amount of emitted light is proportional to the dose deposited in the sensitive volume of the detector by the incoming beam, the intensity distribution of the measured light spot is proportional to the 2D hadron dose distribution. For a measurement of a 3D dose distribution, the scintillating gas detector is mounted at the beam exit side of a water-bellows phantom, whose thickness can be varied in steps. In this work, the energy dependence of the output signal of the scintillating gas detector has been verified in a 250 MeV/u clinical 12C ion beam by means of a depth-dose curve measurement. The underestimation of the measured signal at the Bragg peak depth is only 9% with respect to an air-filled ionization chamber. This is much smaller than the underestimation found for a scintillating Gd2O2S:Tb ('Lanex') screen under the same measurement conditions (43%). Consequently, the scintillating gas detector is a promising device for verifying dose distributions in high LET beams, for example to check hadron therapy treatment plans which comprise beams with different energies. PMID:18695295

  14. A scintillating gas detector for 2D dose measurements in clinical carbon beams

    NASA Astrophysics Data System (ADS)

    Seravalli, E.; de Boer, M.; Geurink, F.; Huizenga, J.; Kreuger, R.; Schippers, J. M.; van Eijk, C. W. E.; Voss, B.

    2008-09-01

    A two-dimensional position sensitive dosimetry system based on a scintillating gas detector has been developed for pre-treatment verification of dose distributions in hadron therapy. The dosimetry system consists of a chamber filled with an Ar/CF4 scintillating gas mixture, inside which two cascaded gas electron multipliers (GEMs) are mounted. A GEM is a thin kapton foil with copper cladding structured with a regular pattern of sub-mm holes. The primary electrons, created in the detector's sensitive volume by the incoming beam, drift in an electric field towards the GEMs and undergo gas multiplication in the GEM holes. During this process, photons are emitted by the excited Ar/CF4 gas molecules and detected by a mirror-lens-CCD camera system. Since the amount of emitted light is proportional to the dose deposited in the sensitive volume of the detector by the incoming beam, the intensity distribution of the measured light spot is proportional to the 2D hadron dose distribution. For a measurement of a 3D dose distribution, the scintillating gas detector is mounted at the beam exit side of a water-bellows phantom, whose thickness can be varied in steps. In this work, the energy dependence of the output signal of the scintillating gas detector has been verified in a 250 MeV/u clinical 12C ion beam by means of a depth-dose curve measurement. The underestimation of the measured signal at the Bragg peak depth is only 9% with respect to an air-filled ionization chamber. This is much smaller than the underestimation found for a scintillating Gd2O2S:Tb ('Lanex') screen under the same measurement conditions (43%). Consequently, the scintillating gas detector is a promising device for verifying dose distributions in high LET beams, for example to check hadron therapy treatment plans which comprise beams with different energies.

  15. Parallel stitching of 2D materials

    DOE PAGESBeta

    Ling, Xi; Wu, Lijun; Lin, Yuxuan; Ma, Qiong; Wang, Ziqiang; Song, Yi; Yu, Lili; Huang, Shengxi; Fang, Wenjing; Zhang, Xu; et al

    2016-01-27

    Diverse parallel stitched 2D heterostructures, including metal–semiconductor, semiconductor–semiconductor, and insulator–semiconductor, are synthesized directly through selective “sowing” of aromatic molecules as the seeds in the chemical vapor deposition (CVD) method. Lastly, the methodology enables the large-scale fabrication of lateral heterostructures, which offers tremendous potential for its application in integrated circuits.

  16. Parallel Stitching of 2D Materials.

    PubMed

    Ling, Xi; Lin, Yuxuan; Ma, Qiong; Wang, Ziqiang; Song, Yi; Yu, Lili; Huang, Shengxi; Fang, Wenjing; Zhang, Xu; Hsu, Allen L; Bie, Yaqing; Lee, Yi-Hsien; Zhu, Yimei; Wu, Lijun; Li, Ju; Jarillo-Herrero, Pablo; Dresselhaus, Mildred; Palacios, Tomás; Kong, Jing

    2016-03-01

    Diverse parallel stitched 2D heterostructures, including metal-semiconductor, semiconductor-semiconductor, and insulator-semiconductor, are synthesized directly through selective "sowing" of aromatic molecules as the seeds in the chemical vapor deposition (CVD) method. The methodology enables the large-scale fabrication of lateral heterostructures, which offers tremendous potential for its application in integrated circuits. PMID:26813882

  17. Baby universes in 2d quantum gravity

    NASA Astrophysics Data System (ADS)

    Ambjørn, Jan; Jain, Sanjay; Thorleifsson, Gudmar

    1993-06-01

    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 γstring.

  18. Close encounters of three black holes

    SciTech Connect

    Campanelli, Manuela; Lousto, Carlos O.; Zlochower, Yosef

    2008-05-15

    We present the first fully relativistic long-term numerical evolutions of three equal-mass black holes in a system consisting of a third black hole in a close orbit about a black-hole binary. These close-three-black-hole systems have very different merger dynamics from black-hole binaries; displaying complex trajectories, a redistribution of energy that can impart substantial kicks to one of the holes, distinctive waveforms, and suppression of the emitted gravitational radiation. In one configuration the binary is quickly disrupted and the individual holes follow complicated trajectories and merge with the third hole in rapid succession, while in another, the binary completes a half-orbit before the initial merger of one of the members with the third black hole, and the resulting two-black-hole system forms a highly elliptical, well separated binary that shows no significant inspiral for (at least) the first t{approx}1000M of evolution.

  19. Woods Hole Image Processing System Software implementation; using NetCDF as a software interface for image processing

    USGS Publications Warehouse

    Paskevich, Valerie F.

    1992-01-01

    The Branch of Atlantic Marine Geology has been involved in the collection, processing and digital mosaicking of high, medium and low-resolution side-scan sonar data during the past 6 years. In the past, processing and digital mosaicking has been accomplished with a dedicated, shore-based computer system. With the need to process sidescan data in the field with increased power and reduced cost of major workstations, a need to have an image processing package on a UNIX based computer system which could be utilized in the field as well as be more generally available to Branch personnel was identified. This report describes the initial development of that package referred to as the Woods Hole Image Processing System (WHIPS). The software was developed using the Unidata NetCDF software interface to allow data to be more readily portable between different computer operating systems.

  20. Stability of spherically symmetric, charged black holes and multipole moments for stationary systems

    NASA Astrophysics Data System (ADS)

    Gursel, Yekta

    This dissertation is written in two parts. Part I deals with the question of stability of a spherically symmetric, charged black hole against scalar, electromagnetic, and gravitational perturbations. It consists of two papers written in collaboration with Igor D. NoVikov, Vernon D. Sandberg and A. A. Starobinsky. In these papers we describe the dynamical evolution of these perturbations on the interior of a Reissner-Nordstrom black hole. The instability of the hole's Cauchy horizon is discussed in detail in terms of the energy densities of the test fields as measured by a freely falling observer approaching the Cauchy horizon. We conclude that the Cauchy horizon of the analytically extended Reissner-Nordstrom solution is highly unstable and not a physical feature of a realistic gravitational collapse. Part II of this dissertation addresses two problems closely connected with muitipole structure of stationary, asymptotically flat spacetimes. It consists of two papers written in collaboration with Kip S. Thorne despite the fact that his name does not appear on one of them. The first one (Paper III in this thesis) shows the equivalence of the moments defined by Kip S. Thorne and the moments defined by Robert Geroch and Richard Hansen. The second (Paper IV in this thesis) proves a conjecture by Kip S. Thorne: In the limit of "slow" motion, general relativistic gravity produces no changes whatsoever in the classical Euler equations of rigid body motion. We prove this conjecture by giving an algorithm for generating rigidly rotating solutions of Einstein's equations from nonrotating, static solutions.

  1. Controlling avalanche criticality in 2D nano arrays

    NASA Astrophysics Data System (ADS)

    Zohar, Y. C.; Yochelis, S.; Dahmen, K. A.; Jung, G.; Paltiel, Y.

    2013-05-01

    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.

  2. A Better 2-D Mechanical Energy Conservation Experiment

    NASA Astrophysics Data System (ADS)

    Paesler, Michael

    2012-02-01

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

  3. Application of 2D Non-Graphene Materials and 2D Oxide Nanostructures for Biosensing Technology

    PubMed Central

    Shavanova, Kateryna; Bakakina, Yulia; Burkova, Inna; Shtepliuk, Ivan; Viter, Roman; Ubelis, Arnolds; Beni, Valerio; Starodub, Nickolaj; Yakimova, Rositsa; Khranovskyy, Volodymyr

    2016-01-01

    The discovery of graphene and its unique properties has inspired researchers to try to invent other two-dimensional (2D) materials. After considerable research effort, a distinct “beyond graphene” domain has been established, comprising the library of non-graphene 2D materials. It is significant that some 2D non-graphene materials possess solid advantages over their predecessor, such as having a direct band gap, and therefore are highly promising for a number of applications. These applications are not limited to nano- and opto-electronics, but have a strong potential in biosensing technologies, as one example. However, since most of the 2D non-graphene materials have been newly discovered, most of the research efforts are concentrated on material synthesis and the investigation of the properties of the material. Applications of 2D non-graphene materials are still at the embryonic stage, and the integration of 2D non-graphene materials into devices is scarcely reported. However, in recent years, numerous reports have blossomed about 2D material-based biosensors, evidencing the growing potential of 2D non-graphene materials for biosensing applications. This review highlights the recent progress in research on the potential of using 2D non-graphene materials and similar oxide nanostructures for different types of biosensors (optical and electrochemical). A wide range of biological targets, such as glucose, dopamine, cortisol, DNA, IgG, bisphenol, ascorbic acid, cytochrome and estradiol, has been reported to be successfully detected by biosensors with transducers made of 2D non-graphene materials. PMID:26861346

  4. Application of 2D Non-Graphene Materials and 2D Oxide Nanostructures for Biosensing Technology.

    PubMed

    Shavanova, Kateryna; Bakakina, Yulia; Burkova, Inna; Shtepliuk, Ivan; Viter, Roman; Ubelis, Arnolds; Beni, Valerio; Starodub, Nickolaj; Yakimova, Rositsa; Khranovskyy, Volodymyr

    2016-01-01

    The discovery of graphene and its unique properties has inspired researchers to try to invent other two-dimensional (2D) materials. After considerable research effort, a distinct "beyond graphene" domain has been established, comprising the library of non-graphene 2D materials. It is significant that some 2D non-graphene materials possess solid advantages over their predecessor, such as having a direct band gap, and therefore are highly promising for a number of applications. These applications are not limited to nano- and opto-electronics, but have a strong potential in biosensing technologies, as one example. However, since most of the 2D non-graphene materials have been newly discovered, most of the research efforts are concentrated on material synthesis and the investigation of the properties of the material. Applications of 2D non-graphene materials are still at the embryonic stage, and the integration of 2D non-graphene materials into devices is scarcely reported. However, in recent years, numerous reports have blossomed about 2D material-based biosensors, evidencing the growing potential of 2D non-graphene materials for biosensing applications. This review highlights the recent progress in research on the potential of using 2D non-graphene materials and similar oxide nanostructures for different types of biosensors (optical and electrochemical). A wide range of biological targets, such as glucose, dopamine, cortisol, DNA, IgG, bisphenol, ascorbic acid, cytochrome and estradiol, has been reported to be successfully detected by biosensors with transducers made of 2D non-graphene materials. PMID:26861346

  5. SU-D-12A-04: Investigation of a 2D Antiscatter Grid for Flat Panel Detectors

    SciTech Connect

    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.

  6. The physics of 2D microfluidic droplet ensembles

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

  7. 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.

  8. NKG2D ligands mediate immunosurveillance of senescent cells

    PubMed Central

    Moshayev, Zhana; Vadai, Ezra; Wensveen, Felix; Ben-Dor, Shifra; Golani, Ofra; Polic, Bojan; Krizhanovsky, Valery

    2016-01-01

    Cellular senescence is a stress response mechanism that limits tumorigenesis and tissue damage. Induction of cellular senescence commonly coincides with an immunogenic phenotype that promotes self-elimination by components of the immune system, thereby facilitating tumor suppression and limiting excess fibrosis during wound repair. The mechanisms by which senescent cells regulate their immune surveillance are not completely understood. Here we show that ligands of an activating Natural Killer (NK) cell receptor (NKG2D), MICA and ULBP2 are consistently up-regulated following induction of replicative senescence, oncogene-induced senescence and DNA damage - induced senescence. MICA and ULBP2 proteins are necessary for efficient NK-mediated cytotoxicity towards senescent fibroblasts. The mechanisms regulating the initial expression of NKG2D ligands in senescent cells are dependent on a DNA damage response, whilst continuous expression of these ligands is regulated by the ERK signaling pathway. In liver fibrosis, the accumulation of senescent activated stellate cells is increased in mice lacking NKG2D receptor leading to increased fibrosis. Overall, our results provide new insights into the mechanisms regulating the expression of immune ligands in senescent cells and reveal the importance of NKG2D receptor-ligand interaction in protecting against liver fibrosis. PMID:26878797

  9. NKG2D ligands mediate immunosurveillance of senescent cells.

    PubMed

    Sagiv, Adi; Burton, Dominick G A; Moshayev, Zhana; Vadai, Ezra; Wensveen, Felix; Ben-Dor, Shifra; Golani, Ofra; Polic, Bojan; Krizhanovsky, Valery

    2016-02-01

    Cellular senescence is a stress response mechanism that limits tumorigenesis and tissue damage. Induction of cellular senescence commonly coincides with an immunogenic phenotype that promotes self-elimination by components of the immune system, thereby facilitating tumor suppression and limiting excess fibrosis during wound repair. The mechanisms by which senescent cells regulate their immune surveillance are not completely understood. Here we show that ligands of an activating Natural Killer (NK) cell receptor (NKG2D), MICA and ULBP2 are consistently up-regulated following induction of replicative senescence, oncogene-induced senescence and DNA damage - induced senescence. MICA and ULBP2 proteins are necessary for efficient NK-mediated cytotoxicity towards senescent fibroblasts. The mechanisms regulating the initial expression of NKG2D ligands in senescent cells are dependent on a DNA damage response, whilst continuous expression of these ligands is regulated by the ERK signaling pathway. In liver fibrosis, the accumulation of senescent activated stellate cells is increased in mice lacking NKG2D receptor leading to increased fibrosis. Overall, our results provide new insights into the mechanisms regulating the expression of immune ligands in senescent cells and reveal the importance of NKG2D receptor-ligand interaction in protecting against liver fibrosis. PMID:26878797

  10. Spherically symmetric systems of fields and black holes. II. Apparent horizon in canonical formalism

    SciTech Connect

    Hajicek, P.

    1984-09-15

    We study the action of a two-dimensional model of gravity found in the preceding paper. We transform the action to the first-order Arnowitt-Deser-Misner form, and work out the generalized momenta and super-Hamiltonians. We propose to foliate the spacetime in such a way that the inside of the apparent horizon will be cut away. In the classical theory, no loss of information for the development of states from scrI/sup -/ to scrI/sup +/ can result, but in the corresponding quantum theory, some such losses could occur if a black hole evaporates. We study the boundary conditions for the fields at the apparent horizon which are implied by such a foliation, and calculate the corresponding surface correction to the Hamiltonian by the method of Regge and Teitelboim. We generalize the so-called Berger-Chitre-Moncrief-Nutku gauge in such a way that the fields cannot violate the boundary conditions. In this gauge, we perform an explicit total reduction of the canonical formalism so that only the true dynamical variables appear in the Hamiltonian. The reduced Hamiltonian splits into a black hole and a field part.

  11. Spherically symmetric systems of fields and black holes. II. Apparent horizon in canonical formalism

    NASA Astrophysics Data System (ADS)

    Hajicek, P.

    1984-09-01

    We study the action of a two-dimensional model of gravity found in the preceding paper. We transform the action to the first-order Arnowitt-Deser-Misner form, and work out the generalized momenta and super-Hamiltonians. We propose to foliate the spacetime in such a way that the inside of the apparent horizon will be cut away. In the classical theory, no loss of information for the development of states from I- to I+ can result, but in the corresponding quantum theory, some such losses could occur if a black hole evaporates. We study the boundary conditions for the fields at the apparent horizon which are implied by such a foliation, and calculate the corresponding surface correction to the Hamiltonian by the method of Regge and Teitelboim. We generalize the socalled Berger-Chitre-Moncrief-Nutku gauge in such a way that the fields cannot violate the boundary conditions. In this gauge, we perform an explicit total reduction of the canonical formalism so that only the true dynamical variables appear in the Hamiltonian. The reduced Hamiltonian splits into a black hole and a field part.

  12. Static & Dynamic Response of 2D Solids

    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

  13. Explicit 2-D Hydrodynamic FEM Program

    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

  14. Schottky diodes from 2D germanane

    NASA Astrophysics Data System (ADS)

    Sahoo, Nanda Gopal; Esteves, Richard J.; Punetha, Vinay Deep; Pestov, Dmitry; Arachchige, Indika U.; McLeskey, James T.

    2016-07-01

    We report on the fabrication and characterization of a Schottky diode made using 2D germanane (hydrogenated germanene). When compared to germanium, the 2D structure has higher electron mobility, an optimal band-gap, and exceptional stability making germanane an outstanding candidate for a variety of opto-electronic devices. One-atom-thick sheets of hydrogenated puckered germanium atoms have been synthesized from a CaGe2 framework via intercalation and characterized by XRD, Raman, and FTIR techniques. The material was then used to fabricate Schottky diodes by suspending the germanane in benzonitrile and drop-casting it onto interdigitated metal electrodes. The devices demonstrate significant rectifying behavior and the outstanding potential of this material.

  15. Layer Engineering of 2D Semiconductor Junctions.

    PubMed

    He, Yongmin; Sobhani, Ali; Lei, Sidong; Zhang, Zhuhua; Gong, Yongji; Jin, Zehua; Zhou, Wu; Yang, Yingchao; Zhang, Yuan; Wang, Xifan; Yakobson, Boris; Vajtai, Robert; Halas, Naomi J; Li, Bo; Xie, Erqing; Ajayan, Pulickel

    2016-07-01

    A new concept for junction fabrication by connecting multiple regions with varying layer thicknesses, based on the thickness dependence, is demonstrated. This type of junction is only possible in super-thin-layered 2D materials, and exhibits similar characteristics as p-n junctions. Rectification and photovoltaic effects are observed in chemically homogeneous MoSe2 junctions between domains of different thicknesses. PMID:27136275

  16. Compact 2-D graphical representation of DNA

    NASA Astrophysics Data System (ADS)

    Randić, Milan; Vračko, Marjan; Zupan, Jure; Novič, 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 β-globin and gorilla β-globin.

  17. 2D materials: Graphene and others

    NASA Astrophysics Data System (ADS)

    Bansal, Suneev Anil; Singh, Amrinder Pal; Kumar, Suresh

    2016-05-01

    Present report reviews the recent advancements in new atomically thick 2D materials. Materials covered in this review are Graphene, Silicene, Germanene, Boron Nitride (BN) and Transition metal chalcogenides (TMC). These materials show extraordinary mechanical, electronic and optical properties which make them suitable candidates for future applications. Apart from unique properties, tune-ability of highly desirable properties of these materials is also an important area to be emphasized on.

  18. TACO (2D AND 3D). Taco

    SciTech Connect

    Mason, W.E.

    1983-03-01

    A set of finite element codes for the solution of nonlinear, two-dimensional (TACO2D) and three-dimensional (TACO3D) heat transfer problems. Performs linear and nonlinear analyses of both transient and steady state heat transfer problems. Has the capability to handle time or temperature dependent material properties. Materials may be either isotropic or orthotropic. A variety of time and temperature dependent boundary conditions and loadings are available including temperature, flux, convection, radiation, and internal heat generation.

  19. CD4+NKG2D+ T Cells Exhibit Enhanced Migratory and Encephalitogenic Properties in Neuroinflammation

    PubMed Central

    Ruck, Tobias; Bittner, Stefan; Gross, Catharina C.; Breuer, Johanna; Albrecht, Stefanie; Korr, Sabrina; Göbel, Kerstin; Pankratz, Susann; Henschel, Christian M.; Schwab, Nicholas; Staszewski, Ori; Prinz, Marco; Kuhlmann, Tanja

    2013-01-01

    Migration of encephalitogenic CD4+ T lymphocytes across the blood-brain barrier is an essential step in the pathogenesis of multiple sclerosis (MS). We here demonstrate that expression of the co-stimulatory receptor NKG2D defines a subpopulation of CD4+ T cells with elevated levels of markers for migration, activation, and cytolytic capacity especially when derived from MS patients. Furthermore, CD4+NKG2D+ cells produce high levels of proinflammatory IFN-γ and IL-17 upon stimulation. NKG2D promotes the capacity of CD4+NKG2D+ cells to migrate across endothelial cells in an in vitro model of the blood-brain barrier. CD4+NKG2D+ T cells are enriched in the cerebrospinal fluid of MS patients, and a significant number of CD4+ T cells in MS lesions coexpress NKG2D. We further elucidated the role of CD4+NKG2D+ T cells in the mouse system. NKG2D blockade restricted central nervous system migration of T lymphocytes in vivo, leading to a significant decrease in the clinical and pathologic severity of experimental autoimmune encephalomyelitis, an animal model of MS. Blockade of NKG2D reduced killing of cultivated mouse oligodendrocytes by activated CD4+ T cells. Taken together, we identify CD4+NKG2D+ cells as a subpopulation of T helper cells with enhanced migratory, encephalitogenic and cytotoxic properties involved in inflammatory CNS lesion development. PMID:24282598

  20. Tomosynthesis imaging with 2D scanning trajectories

    NASA Astrophysics Data System (ADS)

    Khare, Kedar; Claus, Bernhard E. H.; Eberhard, Jeffrey W.

    2011-03-01

    Tomosynthesis imaging in chest radiography provides volumetric information with the potential for improved diagnostic value when compared to the standard AP or LAT projections. In this paper we explore the image quality benefits of 2D scanning trajectories when coupled with advanced image reconstruction approaches. It is intuitively clear that 2D trajectories provide projection data that is more complete in terms of Radon space filling, when compared with conventional tomosynthesis using a linearly scanned source. Incorporating this additional information for obtaining improved image quality is, however, not a straightforward problem. The typical tomosynthesis reconstruction algorithms are based on direct inversion methods e.g. Filtered Backprojection (FBP) or iterative algorithms that are variants of the Algebraic Reconstruction Technique (ART). The FBP approach is fast and provides high frequency details in the image but at the same time introduces streaking artifacts degrading the image quality. The iterative methods can reduce the image artifacts by using image priors but suffer from a slow convergence rate, thereby producing images lacking high frequency details. In this paper we propose using a fast converging optimal gradient iterative scheme that has advantages of both the FBP and iterative methods in that it produces images with high frequency details while reducing the image artifacts. We show that using favorable 2D scanning trajectories along with the proposed reconstruction method has the advantage of providing improved depth information for structures such as the spine and potentially producing images with more isotropic resolution.