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Sample records for anisotropic p-f mixing

  1. Molecular decompostition of anisotropic homogeneous mixed-norm spaces with applications to the boundedness of operators

    DEFF Research Database (Denmark)

    Cleanthous, Galatia; Georgiadis, Athanasios; Nielsen, Morten

    2018-01-01

    Anisotropic homogeneous mixed-norm Besov and Triebel–Lizorkin spaces are introduced and their properties are explored. A discrete adapted ϕ-transform decomposition is obtained. An associated class of almost diagonal operators is introduced and a boundedness result for such operators is obtained....... Molecular decompositions for all the considered spaces are derived with the help of the algebra of almost diagonal operators. As an application, we obtain boundedness results on the considered spaces for Fourier multipliers and for pseudodifferential operators with suitable adapted homogeneous symbols using...

  2. Edge states in a honeycomb lattice: effects of anisotropic hopping and mixed edges

    Energy Technology Data Exchange (ETDEWEB)

    Dahal, Hari P [Los Alamos National Laboratory; Balatsky, Alexander V [Los Alamos National Laboratory; Sinistsyn, N A [Los Alamos National Laboratory; Hu, Zi - Xiang [ZHEJIANG UNIV; Yang, Kun [NHMFL/FSU

    2008-01-01

    We study the edge states in graphene in the presence of a magnetic field perpendicular to the plane of the lattice. Most of the work done so far discusses the edge states in either zigzag or armchair edge graphene considering an isotropic electron hopping. In practice, graphene can have a mixture of armchair and zigzag edges and the electron hopping can be anisotropic, which is the subject of this article. We predict that the mixed edges smear the enhanced local density of states (LDOS) at E=0 of the zigzag edge and, on the other hand, the anisotropic hopping gives rise to the enhanced LDOS at E=0 in the armchair edge. The behavior of the LDOS can be studied using scanning tunneling microscopy (STM) experiments. We suggest that care must be taken while interpreting the STM data, because the clear distinction between the zigzag edge (enhanced LDOS at E=0) and armchair edge (suppressed LDOS at E=0) can be lost if the hopping is not isotropic and if the edges are mixed.

  3. Mixed conduction and anisotropic single oscillator parameters in low dimensional TlInSe{sub 2} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Qasrawi, A.F., E-mail: aqasrawi@atilim.edu.tr [Group of Physics, Faculty of Engineering, Atilim University, 06836 Ankara (Turkey); Department of Physics, Arab-American University, Jenin, West Bank, Palestine (Country Unknown); Gasanly, N.M. [Department of Physics, Middle East Technical University, 06800 Ankara (Turkey)

    2013-08-15

    Due to the importance of the TlInSe{sub 2} crystal as neutron and γ-ray detectors, its electrical and dispersive optical parameters have been investigated. Particularly, the anisotropic current conduction mechanism in the temperature region of 100–350 K and the room temperature anisotropic dispersive optical properties were studied by means of electrical conductivity and optical reflectance, respectively. It has been shown that the mixed conduction is the most dominant transport mechanism in the TlInSe{sub 2} crystals. Particularly, when the electric field is applied perpendicular to the crystal's c-axis, the main dominant current transport mechanism is due to the mixed conduction and the variable range hopping above and below 160 K, respectively. When the electric field is applied parallel to the crystal's c-axis, the electrical conductivity is dominated by the thermionic emission, mixed conduction and variable range hopping at high, moderate and low temperatures, respectively. The optical reflectivity analysis in the wavelength range 210–1500 nm revealed a clear anisotropy effect on the dispersive optical parameters. Particularly, the static refractive index, static dielectric constant, dispersion energy and oscillator energy exhibited values of 2.50, 6.24, 20.72 eV and 3.96 eV, and values of 3.05, 9.33, 39.27 eV and 4.72 eV for light propagation parallel and perpendicular to the crystal's c-axis, respectively. Moreover, the frequency dependence of the dielectric constant, ε(ω), reflected strong dielectric anisotropy that exhibit maximum ε(ω) value of 38.80 and 11.40 at frequencies of 11.07 × 10{sup 14} Hz for light propagation parallel and perpendicular to the crystal's c-axis, respectively. The anisotropy in the ε(ω) makes the TlInSe{sub 2} crystals attractive to be used as nonvolatile static memory devices. - Graphical abstract: Display Omitted - Highlights: • The anisotropic transport mechanism in low dimensional TlInSe{sub 2

  4. Simulating propagation of decoupled elastic waves using low-rank approximate mixed-domain integral operators for anisotropic media

    KAUST Repository

    Cheng, Jiubing

    2016-03-15

    In elastic imaging, the extrapolated vector fields are decoupled into pure wave modes, such that the imaging condition produces interpretable images. Conventionally, mode decoupling in anisotropic media is costly because the operators involved are dependent on the velocity, and thus they are not stationary. We have developed an efficient pseudospectral approach to directly extrapolate the decoupled elastic waves using low-rank approximate mixed-domain integral operators on the basis of the elastic displacement wave equation. We have applied k-space adjustment to the pseudospectral solution to allow for a relatively large extrapolation time step. The low-rank approximation was, thus, applied to the spectral operators that simultaneously extrapolate and decompose the elastic wavefields. Synthetic examples on transversely isotropic and orthorhombic models showed that our approach has the potential to efficiently and accurately simulate the propagations of the decoupled quasi-P and quasi-S modes as well as the total wavefields for elastic wave modeling, imaging, and inversion.

  5. [Clinical medicine of P. F. von Siebold].

    Science.gov (United States)

    Nakamura, A

    1995-03-01

    The author elucidates some aspects of the clinical medicine of P.F. von Siebold (1796-1866) by studying a manuscript titled "Rampō-kuden, namely, dictative teaching of Dutch medicine by P.F. von Siebold", which has not been studied enough yet. From this manuscript the author considers the descriptions about cancers, gynecological diseases, syphilitic diseases, urinary diseases, ophthalmic diseases, skin diseases, pulmonary diseases, gastrointestinal diseases and osteo-articular diseases, and thereby shows the concepts and therapeutic techniques of P.F. von Siebold regarding these diseases. To make his therapeutics more clearly understood, the author comments on blood-letting, opiates, emetics, purgatives, peruvian bark, digitalis, physiotherapy, abdominal paracentesis and surgical operations written in this manuscript.

  6. The Anisotropic Aphid: Three-Dimensional Induction Modeling of Electrical Texture with Mixed Potentials

    Science.gov (United States)

    Weiss, C. J.

    2014-12-01

    At the macroscopic scale, where the e-folding distance of low-frequency electromagnetic fields in conductive geomaterials is much larger than the size of organized heterogeneities such as fracture sets or laminations that constitute the geologic texture therein, electrical properties can be conveniently approximated by a generalized 3x3 tensor σ. Less convenient, however, are the algorithmic consequences of this approximation in electromagnetic modeling of 3D induction methods for geophysical exploration. Previous efforts at modelling generalized anisotropy with finite differences on a staggered Cartesian grid (e.g. Weiss and Newman, 2002; Wang and Fang, 2001) are posed in terms of the electric field with its governing "curl-curl" equation and well-documented null-space issues at low induction numbers. In contrast, Weiss (2013) proposed an alternate full-physics formulation in terms of Lorenz-gauged magentic vector A and electric scalar Φ potentials (Project APhiD) that eliminates the troublesome curl-curl operator, with ultrabroadband examples drawn from geologies with scalar, isotropic conductivity over the frequency range 10-2-1010 Hz. Here, the anisotropic theory presented in Weiss (2013) is implemented with finite differences on a Cartesian grid. Briefly stated, in this theoretical approach the conductivity tensor σ is split in terms of a rotationally-invariant isotropic conductivity σ* = ⅓ Tr(σ) and the residual σ - σ*I. This splitting decomposes the resulting finite difference coefficient matrix K into the sum Kiso + Kaniso, where the Kiso term is the coefficient matrix for the isotropic medium σ*, thus enabling reuse of the various routines previously developed for computing matrix coefficients in the isotropic case. Treatment of anisotropy is algorithmically therefore restricted to computing the coefficients in the sparse matrix Kaniso consisting of simple inner products of (σ - σ*I) · (A-∇Φ) and their divergence. In keeping with the

  7. A Note on Protancylus P. & F. Sarasin

    NARCIS (Netherlands)

    Hubendick, Bengt

    1958-01-01

    In their account of the fresh water molluscs of Celebes P. & F. SARASIN (1898) described the genus Protancylus. They pointed out certain resemblances between Protancylus and Ancylus as well as between Protancylus and ”Miratesta, Isidora und Planorbis”. However, they did not present any conclusion

  8. Material Induced Anisotropic Damage

    NARCIS (Netherlands)

    Niazi, Muhammad Sohail; Wisselink, H.H.; Meinders, Vincent T.; van den Boogaard, Antonius H.; Hora, P.

    2012-01-01

    The anisotropy in damage can be driven by two different phenomena; anisotropic defor-mation state named Load Induced Anisotropic Damage (LIAD) and anisotropic (shape and/or distribution) second phase particles named Material Induced Anisotropic Damage (MIAD). Most anisotropic damage models are based

  9. Anisotropic universe with anisotropic sources

    Science.gov (United States)

    Aluri, Pavan K.; Panda, Sukanta; Sharma, Manabendra; Thakur, Snigdha

    2013-12-01

    We analyze the state space of a Bianchi-I universe with anisotropic sources. Here we consider an extended state space which includes null geodesics in this background. The evolution equations for all the state observables are derived. Dynamical systems approach is used to study the evolution of these equations. The asymptotic stable fixed points for all the evolution equations are found. We also check our analytic results with numerical analysis of these dynamical equations. The evolution of the state observables are studied both in cosmic time and using a dimensionless time variable. Then we repeat the same analysis with a more realistic scenario, adding the isotropic (dust like dark) matter and a cosmological constant (dark energy) to our anisotropic sources, to study their co-evolution. The universe now approaches a de Sitter space asymptotically dominated by the cosmological constant. The cosmic microwave background anisotropy maps due to shear are also generated in this scenario, assuming that the universe contains anisotropic matter along with the usual (dark) matter and vacuum (dark) energy since decoupling. We find that they contribute dominantly to the CMB quadrupole. We also constrain the current level of anisotropy and also search for any cosmic preferred axis present in the data. We use the Union 2 Supernovae data to this extent. An anisotropy axis close to the mirror symmetry axis seen in the cosmic microwave background data from Planck probe is found.

  10. Anisotropic Mg Electrodeposition and Alloying with Ag-based Anodes from Non-Coordinating Mixed-Metal Borohydride Electrolytes for Mg Hybrid Batteries

    International Nuclear Information System (INIS)

    Wetzel, David J.; Malone, Marvin A.; Gewirth, Andrew A.; Nuzzo, Ralph G.

    2017-01-01

    A highly anisotropic electrodeposition was observed using the hybrid battery electrolyte Mg(BH 4 ) 2 with LiBH 4 in diglyme. At low overpotentials high aspect ratio platelet morphologies are observed with a strong fiber texture composed of a {10-10} and a {11-20} component, the first evidence of behavior of this kind in magnesium battery electrolytes. At high overpotentials the deposit aspect ratio is indistinguishable but the texture is shown to be primarily composed of a {11-20} fiber texture. The kinetic parameters relative to the relevant crystallographic faces are extracted from electron microscopy images and compared with the observed bulk rate extracted from the electrochemical data. The use of polycrystalline Ag foil substrates with little preferred orientation at the surface allowed highly polycrystalline nucleation at lower overpotentials than that of platinum, likely due to Ag alloying with Mg. Characterization using focused ion beam (FIB) cross-sections with Auger Electron Spectroscopy (AES) elemental analysis confirm that the deposits are primarily Mg although Mg‐Ag alloys of various compositions were observed. It is proposed that the orientation at slow rates of growth is due to the underlying kinetics of adatom diffusion on Mg and that higher rates diminish the phenomenon due to decreased time for adatom diffusion and instead are governed by the rates of adatom formation or more specifically the adatom vacancy formation on the different low-index planes of Mg.

  11. Highly Anisotropic Conductors.

    Science.gov (United States)

    Wan, Jiayu; Song, Jianwei; Yang, Zhi; Kirsch, Dylan; Jia, Chao; Xu, Rui; Dai, Jiaqi; Zhu, Mingwei; Xu, Lisha; Chen, Chaoji; Wang, Yanbin; Wang, Yilin; Hitz, Emily; Lacey, Steven D; Li, Yongfeng; Yang, Bao; Hu, Liangbing

    2017-11-01

    Composite materials with ordered microstructures often lead to enhanced functionalities that a single material can hardly achieve. Many biomaterials with unusual microstructures can be found in nature; among them, many possess anisotropic and even directional physical and chemical properties. With inspiration from nature, artificial composite materials can be rationally designed to achieve this anisotropic behavior with desired properties. Here, a metallic wood with metal continuously filling the wood vessels is developed, which demonstrates excellent anisotropic electrical, thermal, and mechanical properties. The well-aligned metal rods are confined and separated by the wood vessels, which deliver directional electron transport parallel to the alignment direction. Thus, the novel metallic wood composite boasts an extraordinary anisotropic electrical conductivity (σ || /σ ⊥ ) in the order of 10 11 , and anisotropic thermal conductivity (κ || /κ ⊥ ) of 18. These values exceed the highest reported values in existing anisotropic composite materials. The anisotropic functionality of the metallic wood enables it to be used for thermal management applications, such as thermal insulation and thermal dissipation. The highly anisotropic metallic wood serves as an example for further anisotropic materials design; other composite materials with different biotemplates/hosts and fillers can achieve even higher anisotropic ratios, allowing them to be implemented in a variety of applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Mixed

    Directory of Open Access Journals (Sweden)

    Pau Baya

    2011-05-01

    Full Text Available Remenat (Catalan (Mixed, "revoltillo" (Scrambled in Spanish, is a dish which, in Catalunya, consists of a beaten egg cooked with vegetables or other ingredients, normally prawns or asparagus. It is delicious. Scrambled refers to the action of mixing the beaten egg with other ingredients in a pan, normally using a wooden spoon Thought is frequently an amalgam of past ideas put through a spinner and rhythmically shaken around like a cocktail until a uniform and dense paste is made. This malleable product, rather like a cake mixture can be deformed pulling it out, rolling it around, adapting its shape to the commands of one’s hands or the tool which is being used on it. In the piece Mixed, the contortion of the wood seeks to reproduce the plasticity of this slow heavy movement. Each piece lays itself on the next piece consecutively like a tongue of incandescent lava slowly advancing but with unstoppable inertia.

  13. Anomalous behaviour of the magnetic susceptibility of the mixed spin-1 and spin- 1/2 anisotropic Heisenberg model in the Oguchi approximation

    International Nuclear Information System (INIS)

    Bobak, Andrej; Dely, Jan; Pokorny, Vladislav

    2010-01-01

    The effects of both an exchange anisotropy and a single-ion anisotropy on the magnetic susceptibility of the mixed spin-1 and spin- 1/2 Heisenberg model are investigated by the use of an Oguchi approximation. Particular emphasis is given to the simple cubic lattice with coordination number z = 6 for which the magnetic susceptibility is determined numerically. Anomalous behaviour in the thermal variation of the magnetic susceptibility in the low-temperature region is found due to the applied negative single-ion anisotropy field strength. Also, the difference between the behaviours of the magnetic susceptibility of the Heisenberg and Ising models is discussed.

  14. Anisotropic light diffusion: an oxymoron?

    Science.gov (United States)

    Kienle, Alwin

    2007-05-25

    Light propagation in anisotropic random media is studied in the steady-state and time domains. Solutions of the anisotropic diffusion equation are compared to results obtained by the Monte Carlo method. Contrary to what has been reported so far, we find that even in the "diffusive regime" the anisotropic diffusion equation does not describe correctly the light propagation in anisotropic random media.

  15. Anisotropic ray trace

    Science.gov (United States)

    Lam, Wai Sze Tiffany

    Optical components made of anisotropic materials, such as crystal polarizers and crystal waveplates, are widely used in many complex optical system, such as display systems, microlithography, biomedical imaging and many other optical systems, and induce more complex aberrations than optical components made of isotropic materials. The goal of this dissertation is to accurately simulate the performance of optical systems with anisotropic materials using polarization ray trace. This work extends the polarization ray tracing calculus to incorporate ray tracing through anisotropic materials, including uniaxial, biaxial and optically active materials. The 3D polarization ray tracing calculus is an invaluable tool for analyzing polarization properties of an optical system. The 3x3 polarization ray tracing P matrix developed for anisotropic ray trace assists tracking the 3D polarization transformations along a ray path with series of surfaces in an optical system. To better represent the anisotropic light-matter interactions, the definition of the P matrix is generalized to incorporate not only the polarization change at a refraction/reflection interface, but also the induced optical phase accumulation as light propagates through the anisotropic medium. This enables realistic modeling of crystalline polarization elements, such as crystal waveplates and crystal polarizers. The wavefront and polarization aberrations of these anisotropic components are more complex than those of isotropic optical components and can be evaluated from the resultant P matrix for each eigen-wavefront as well as for the overall image. One incident ray refracting or reflecting into an anisotropic medium produces two eigenpolarizations or eigenmodes propagating in different directions. The associated ray parameters of these modes necessary for the anisotropic ray trace are described in Chapter 2. The algorithms to calculate the P matrix from these ray parameters are described in Chapter 3 for

  16. Anisotropic contrast optical microscope.

    Science.gov (United States)

    Peev, D; Hofmann, T; Kananizadeh, N; Beeram, S; Rodriguez, E; Wimer, S; Rodenhausen, K B; Herzinger, C M; Kasputis, T; Pfaunmiller, E; Nguyen, A; Korlacki, R; Pannier, A; Li, Y; Schubert, E; Hage, D; Schubert, M

    2016-11-01

    An optical microscope is described that reveals contrast in the Mueller matrix images of a thin, transparent, or semi-transparent specimen located within an anisotropic object plane (anisotropic filter). The specimen changes the anisotropy of the filter and thereby produces contrast within the Mueller matrix images. Here we use an anisotropic filter composed of a semi-transparent, nanostructured thin film with sub-wavelength thickness placed within the object plane. The sample is illuminated as in common optical microscopy but the light is modulated in its polarization using combinations of linear polarizers and phase plate (compensator) to control and analyze the state of polarization. Direct generalized ellipsometry data analysis approaches permit extraction of fundamental Mueller matrix object plane images dispensing with the need of Fourier expansion methods. Generalized ellipsometry model approaches are used for quantitative image analyses. These images are obtained from sets of multiple images obtained under various polarizer, analyzer, and compensator settings. Up to 16 independent Mueller matrix images can be obtained, while our current setup is limited to 11 images normalized by the unpolarized intensity. We demonstrate the anisotropic contrast optical microscope by measuring lithographically defined micro-patterned anisotropic filters, and we quantify the adsorption of an organic self-assembled monolayer film onto the anisotropic filter. Comparison with an isotropic glass slide demonstrates the image enhancement obtained by our method over microscopy without the use of an anisotropic filter. In our current instrument, we estimate the limit of detection for organic volumetric mass within the object plane of ≈49 fg within ≈7 × 7 μm 2 object surface area. Compared to a quartz crystal microbalance with dissipation instrumentation, where contemporary limits require a total load of ≈500 pg for detection, the instrumentation demonstrated here improves

  17. Anisotropic Weyl invariance

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Nadal, Guillem [Universidad de Buenos Aires, Buenos Aires (Argentina)

    2017-07-15

    We consider a non-relativistic free scalar field theory with a type of anisotropic scale invariance in which the number of coordinates ''scaling like time'' is generically greater than one. We propose the Cartesian product of two curved spaces, the metric of each space being parameterized by the other space, as a notion of curved background to which the theory can be extended. We study this type of geometries, and find a family of extensions of the theory to curved backgrounds in which the anisotropic scale invariance is promoted to a local, Weyl-type symmetry. (orig.)

  18. Impacts of P-f & Q-V Droop Control on MicroGrids Transient Stability

    Science.gov (United States)

    Zhao-xia, Xiao; Hong-wei, Fang

    Impacts of P-f & Q-V droop control on MicroGrid transient stability was investigated with a wind unit of asynchronous generator in the MicroGrid. The system frequency stability was explored when the motor load starts and its load power changes, and faults of different types and different locations occurs. The simulations were done by PSCAD/EMTDC.

  19. H.H. Meissner: H.P.F.du Preez and P.C. du Plessis

    African Journals Online (AJOL)

    H.H. Meissner: H.P.F.du Preez and P.C. du Plessis. Department of Livestock Science, University of Pretoria, Pretoria, 0002 Republic of South Africa. Optimal ...... varying bypass amino acids and glucose availability on lamb growth and wool growth. Proc. Austr. Soc. Anim. Prod. 12, 143. MACRAE, J.C. & LOBLEY, G.E., 1986.

  20. Anisotropic Lyra cosmology

    Indian Academy of Sciences (India)

    Anisotropic Bianchi Type-I cosmological models have been studied on the basis of Lyra's geometry. Two types of models, one with constant deceleration parameter and the other with variable deceleration parameter have been derived by considering a time-dependent displacement field.

  1. Anisotropic Concrete Compressive Strength

    DEFF Research Database (Denmark)

    Gustenhoff Hansen, Søren; Jørgensen, Henrik Brøner; Hoang, Linh Cao

    2017-01-01

    When the load carrying capacity of existing concrete structures is (re-)assessed it is often based on compressive strength of cores drilled out from the structure. Existing studies show that the core compressive strength is anisotropic; i.e. it depends on whether the cores are drilled parallel...

  2. Dynamics of anisotropic particles under waves

    Science.gov (United States)

    Dibenedetto, Michelle; Ouellette, Nicholas; Koseff, Jeffrey

    2017-11-01

    We present results on anisotropic particles in wavy flows in order to gain insight into the transport and mixing of microplastic particles in the near-shore environment. From theory and numerical simulations, we find that the rate of alignment of the particles is not constant and depends strongly on their initial orientation; thus, variations in initial particle orientation result in dispersion of anisotropic-particle plumes. We find that this dispersion is a function of the particle's eccentricity and the ratio of the settling and wave time scales. Experiments in which non-spherical particles of various shapes are released under surface gravity waves were also performed. Our main goal is to explore the effects of particle shape under various wave scenarios. We vary the aspect ratio of the particle in our experiments while holding other variables constant. Our results demonstrate that particle shape can be important when predicting transport.

  3. Anisotropic elliptic optical fibers

    Science.gov (United States)

    Kang, Soon Ahm

    1991-05-01

    The exact characteristic equation for an anisotropic elliptic optical fiber is obtained for odd and even hybrid modes in terms of infinite determinants utilizing Mathieu and modified Mathieu functions. A simplified characteristic equation is obtained by applying the weakly guiding approximation such that the difference in the refractive indices of the core and the cladding is small. The simplified characteristic equation is used to compute the normalized guide wavelength for an elliptical fiber. When the anisotropic parameter is equal to unity, the results are compared with the previous research and they are in close agreement. For a fixed value normalized cross-section area or major axis, the normalized guide wavelength lambda/lambda(sub 0) for an anisotropic elliptic fiber is small for the larger value of anisotropy. This condition indicates that more energy is carried inside of the fiber. However, the geometry and anisotropy of the fiber have a smaller effect when the normalized cross-section area is very small or very large.

  4. An anisotropic tertiary creep damage constitutive model for anisotropic materials

    International Nuclear Information System (INIS)

    Stewart, Calvin M.; Gordon, Ali P.; Ma, Young Wha; Neu, Richard W.

    2011-01-01

    When an anisotropic material is subject to creep conditions and a complex state of stress, an anisotropic creep damage behavior is observed. Previous research has focused on the anisotropic creep damage behavior of isotropic materials but few constitutive models have been developed for anisotropic creeping solids. This paper describes the development of a new anisotropic tertiary creep damage constitutive model for anisotropic materials. An advanced tensorial damage formulation is implemented which includes both material orientation relative to loading and the degree of creep damage anisotropy in the model. A variation of the Norton-power law for secondary creep is implemented which includes the Hill's anisotropic analogy. Experiments are conducted on the directionally-solidified bucket material DS GTD-111. The constitutive model is implemented in a user programmable feature (UPF) in ANSYS FEA software. The ability of the constitutive model to regress to the Kachanov-Rabotnov isotropic tertiary creep damage model is demonstrated through comparison with uniaxial experiments. A parametric study of both material orientation and stress rotation are conducted. Results indicate that creep deformation is modeled accurately; however an improved damage evolution law may be necessary. - Highlights: → The deformation of anisotropic creeping solid is directionally dependent. → Few constitutive models have been developed to deal with anisotropic behavior. → A transversely-isotropic nickel base superalloy, DS GTD-111, is studied. → A vector constitutive model based on the Kachanov-Rabotnov formulation is developed. → The new model accurately models deformation at various orientations.

  5. Material Induced Anisotropic Damage in DP600

    NARCIS (Netherlands)

    Niazi, Muhammad Sohail; Wisselink, H.H.; Meinders, Vincent T.; van den Boogaard, Antonius H.

    2013-01-01

    Plasticity induced damage development in metals is anisotropic by nature. The anisotropy in damage is driven by two different phenomena; anisotropic deformation state i.e. Load Induced Anisotropic Damage (LIAD) and anisotropic microstructure i.e. Material Induced Anisotropic Damage (MIAD). The

  6. pF3D Simulations of Large Outer-Beam Brillouin Scattering from NIF Rugby Hohlraums

    Science.gov (United States)

    Langer, Steven; Strozzi, David; Chapman, Thomas; Amendt, Peter

    2015-11-01

    We assess the cause of large outer-beam stimulated Brillouin scattering (SBS) in a NIF shot with a rugby-shaped hohlraum, which has less wall surface loss and thus higher x-ray drive than a cylindrical hohlraum of the same radius. This shot differed from a prior rugby shot with low SBS in three ways: outer beam pointing, split-pointing of the four beams within each outer-beam quadruplet, and a small amount of neon added to the hohlraum helium fill gas. We use pF3D, a massively-parallel, paraxial-envelope laser plasma interaction code, with plasma profiles from the radiation-hydrodynamics code Lasnex. We determine which change between the two shots increased the SBS by adding them one at a time to the simulations. We compare the simulations to experimental data for total SBS power, its spatial distribution at the lens, and the SBS spectrum. For each shot, we use profiles from Lasnex simulations with and without a model for mix at the hohlraum wall-gas interface. Work performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344. Release number LLNL-ABS-674893.

  7. Anisotropic Concrete Compressive Strength

    DEFF Research Database (Denmark)

    Gustenhoff Hansen, Søren; Jørgensen, Henrik Brøner; Hoang, Linh Cao

    2017-01-01

    When the load carrying capacity of existing concrete structures is (re-)assessed it is often based on compressive strength of cores drilled out from the structure. Existing studies show that the core compressive strength is anisotropic; i.e. it depends on whether the cores are drilled parallel...... correlation to the curing time. The experiments show no correlation between the anisotropy and the curing time and a small strength difference between the two drilling directions. The literature shows variations on which drilling direction that is strongest. Based on a Monto Carlo simulation of the expected...

  8. Transient anisotropic magnetic field calculation

    International Nuclear Information System (INIS)

    Jesenik, Marko; Gorican, Viktor; Trlep, Mladen; Hamler, Anton; Stumberger, Bojan

    2006-01-01

    For anisotropic magnetic material, nonlinear magnetic characteristics of the material are described with magnetization curves for different magnetization directions. The paper presents transient finite element calculation of the magnetic field in the anisotropic magnetic material based on the measured magnetization curves for different magnetization directions. For the verification of the calculation method some results of the calculation are compared with the measurement

  9. Thermodynamics of anisotropic branes

    Energy Technology Data Exchange (ETDEWEB)

    Ávila, Daniel [Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México, A.P. 70-542, México D.F. 04510 (Mexico); Fernández, Daniel [Max-Planck-Institut für Physik,Föhringer Ring 6, 80805 München (Germany); Patiño, Leonardo [Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México, A.P. 70-542, México D.F. 04510 (Mexico); Trancanelli, Diego [Institute of Physics, University of São Paulo,05314-970 São Paulo (Brazil)

    2016-11-22

    We study the thermodynamics of flavor D7-branes embedded in an anisotropic black brane solution of type IIB supergravity. The flavor branes undergo a phase transition between a ‘Minkowski embedding’, in which they lie outside of the horizon, and a ‘black hole embedding’, in which they fall into the horizon. This transition depends on the black hole temperature, its degree of anisotropy, and the mass of the flavor degrees of freedom. It happens either at a critical temperature or at a critical anisotropy. A general lesson we learn from this analysis is that the anisotropy, in this particular realization, induces similar effects as the temperature. In particular, increasing the anisotropy bends the branes more and more into the horizon. Moreover, we observe that the transition becomes smoother for higher anisotropies.

  10. Anisotropic Rabi model

    Directory of Open Access Journals (Sweden)

    Qiong-Tao Xie

    2014-06-01

    Full Text Available We define the anisotropic Rabi model as the generalization of the spin-boson Rabi model: The Hamiltonian system breaks the parity symmetry; the rotating and counterrotating interactions are governed by two different coupling constants; a further parameter introduces a phase factor in the counterrotating terms. The exact energy spectrum and eigenstates of the generalized model are worked out. The solution is obtained as an elaboration of a recently proposed method for the isotropic limit of the model. In this way, we provide a long-sought solution of a cascade of models with immediate relevance in different physical fields, including (i quantum optics, a two-level atom in single-mode cross-electric and magnetic fields; (ii solid-state physics, electrons in semiconductors with Rashba and Dresselhaus spin-orbit coupling; and (iii mesoscopic physics, Josephson-junction flux-qubit quantum circuits.

  11. Measurements of nitrous oxide emissions from P.F. fired power stations

    Science.gov (United States)

    Sloan, S. A.; Laird, C. K.

    Nitrous oxide (N 2O) was measured in the flue gas from four wall-fired and three corner-fired 500 MW boilers, fitted with either conventional or low-NO x burners, at four C.E.G.B. power stations. Measurements were made both by on-line non-dispersive infra red (NDIR) monitors and by extractive sampling for later laboratory analysis by electron capture gas chromatography (ECD GC). It was found that the on-line and laboratory methods were in good agreement for samples analyzed within 1-3 h of sampling, but that the nitrous oxide concentration in the stored samples had a tendency to increase with time, which was dependent on the concentration of water in the sample. Experiments with synthetic mixtures showed that the increase in nitrous oxide concentration was consistent with the overall reaction2NO+SO 2→N 2O+SO 3 in which nitric oxide is reduced by sulphur dioxide. The highest average N 2O concentration measured by the on-line analyzer was 16 vpm, and for most of the boilers monitored the concentration was less than 10 vpm. There was no statistically significant difference between the measured N 2O emissions from normal boilers and those fitted with low-NO x burners. It is suggested that these values are close to the true levels of N 2O emissions from p.f. fired boilers and that recent reports of high levels (up to 200 vpm) are likely to be an artefact resulting from the observed generation of N 2O in stored samples. A consequence of these measurements of N 2O is that current estimates of the contribution of emissions from p.f. fired boilers to the global N 2O budget are likely to be too high.

  12. Thermodynamics and instabilities of a strongly coupled anisotropic plasma

    Science.gov (United States)

    Mateos, David; Trancanelli, Diego

    2011-07-01

    We extend our analysis of a IIB supergravity solution dual to a spatially anisotropic finite-temperature mathcal{N} = 4 super Yang-Mills plasma. The solution is static, possesses an anisotropic horizon, and is completely regular. The full geometry can be viewed as a renormalization group flow from an AdS geometry in the ultraviolet to a Lifshitz-like geometry in the infrared. The anisotropy can be equivalently understood as resulting from a position-dependent θ-term or from a non-zero number density of dissolved D7-branes. The holographic stress tensor is conserved and anisotropic. The presence of a conformal anomaly plays an important role in the thermodynamics. The phase diagram exhibits homogeneous and inhomogeneous (i.e. mixed) phases. In some regions the homogeneous phase displays instabilities reminiscent of those of weakly coupled plasmas. We comment on similarities with QCD at finite baryon density and with the phenomenon of cavitation.

  13. Disadvantage factor for anisotropic scattering

    International Nuclear Information System (INIS)

    Saad, E.A.; Abdel Krim, M.S.; EL-Dimerdash, A.A.

    1990-01-01

    The invariant embedding method is used to solve the problem for a two region reactor with anisotropic scattering and to compute the disadvantage factor necessary for calculating some reactor parameters

  14. Photon states in anisotropic media

    Indian Academy of Sciences (India)

    Abstract. Quantum aspects of optical polarization are discussed for waves traveling in anisotropic dielectric media with a view to relate the dynamics of polarization with that of photon spin and its manipulation by classical polarizers.

  15. Anisotropic nonequilibrium hydrodynamic attractor

    Science.gov (United States)

    Strickland, Michael; Noronha, Jorge; Denicol, Gabriel S.

    2018-02-01

    We determine the dynamical attractors associated with anisotropic hydrodynamics (aHydro) and the DNMR equations for a 0 +1 d conformal system using kinetic theory in the relaxation time approximation. We compare our results to the nonequilibrium attractor obtained from the exact solution of the 0 +1 d conformal Boltzmann equation, the Navier-Stokes theory, and the second-order Mueller-Israel-Stewart theory. We demonstrate that the aHydro attractor equation resums an infinite number of terms in the inverse Reynolds number. The resulting resummed aHydro attractor possesses a positive longitudinal-to-transverse pressure ratio and is virtually indistinguishable from the exact attractor. This suggests that an optimized hydrodynamic treatment of kinetic theory involves a resummation not only in gradients (Knudsen number) but also in the inverse Reynolds number. We also demonstrate that the DNMR result provides a better approximation of the exact kinetic theory attractor than the Mueller-Israel-Stewart theory. Finally, we introduce a new method for obtaining approximate aHydro equations which relies solely on an expansion in the inverse Reynolds number. We then carry this expansion out to the third order, and compare these third-order results to the exact kinetic theory solution.

  16. Estimation and Removing of Anisotropic Scattering for Multiaspect Polarimetric SAR Image

    Directory of Open Access Journals (Sweden)

    Li Yang

    2015-06-01

    Full Text Available Multiaspect Synthetic Aperture Radar (SAR can generate high resolution images and target scattering signatures in different azimuth angles from the coherent integration of all subaperture images. However, mixed anisotropic scatters limit the application of traditional imaging theory. Anisotropic scattering may introduce errors in polarimetric parameters by decreasing the reliability of terrain classification and detection of variability. Thus a method is proposed for estimating and removing anisotropic scattering in multiaspect polarimetric SAR images. The proposed algorithm is based on the maximum likelihood and likelihood-ratio tests for the two-class case, while considering the speckle effect, the mechanism of removing the anisotropic scattering, and the monotonicity of the Constant False Alarm Rate (CFAR detection function. We compare the polarimetric entropy before and after removing the anisotropic subapertures, and then validate the algorithm's potential in retrieving the target signature using a P-band quad-pol airborne SAR with circular trajectory.

  17. Continuum mechanics of anisotropic materials

    CERN Document Server

    Cowin, Stephen C

    2013-01-01

    Continuum Mechanics of Anisotropic Materials(CMAM) presents an entirely new and unique development of material anisotropy in the context of an appropriate selection and organization of continuum mechanics topics. These features will distinguish this continuum mechanics book from other books on this subject. Textbooks on continuum mechanics are widely employed in engineering education, however, none of them deal specifically with anisotropy in materials. For the audience of Biomedical, Chemical and Civil Engineering students, these materials will be dealt with more frequently and greater accuracy in their analysis will be desired. Continuum Mechanics of Anisotropic Materials' author has been a leader in the field of developing new approaches for the understanding of anisotropic materials.

  18. Anisotropic hydrodynamics: Motivation and methodology

    Energy Technology Data Exchange (ETDEWEB)

    Strickland, Michael

    2014-06-15

    In this proceedings contribution I review recent progress in our understanding of the bulk dynamics of relativistic systems that possess potentially large local rest frame momentum-space anisotropies. In order to deal with these momentum-space anisotropies, a reorganization of relativistic viscous hydrodynamics can be made around an anisotropic background, and the resulting dynamical framework has been dubbed “anisotropic hydrodynamics”. I also discuss expectations for the degree of momentum-space anisotropy of the quark–gluon plasma generated in relativistic heavy ion collisions at RHIC and LHC from second-order viscous hydrodynamics, strong-coupling approaches, and weak-coupling approaches.

  19. Magnetic relaxation in anisotropic magnets

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1971-01-01

    The line shape and the kinematic and thermodynamic slowing down of the critical and paramagnetic relaxation in axially anisotropic materials are discussed. Kinematic slowing down occurs only in the longitudinal relaxation function. The thermodynamic slowing down occurs in either the transverse...

  20. Failure in imperfect anisotropic materials

    DEFF Research Database (Denmark)

    Legarth, Brian Nyvang

    2005-01-01

    The fundamental cause of crack growth, namely nucleation and growth of voids, is investigated numerically for a two phase imperfect anisotropic material. A unit cell approach is adopted from which the overall stress strain is evaluated. Failure is observed as a sudden stress drop and depending...

  1. Effective wavefield extrapolation in anisotropic media: Accounting for resolvable anisotropy

    KAUST Repository

    Alkhalifah, Tariq Ali

    2014-04-30

    Spectral methods provide artefact-free and generally dispersion-free wavefield extrapolation in anisotropic media. Their apparent weakness is in accessing the medium-inhomogeneity information in an efficient manner. This is usually handled through a velocity-weighted summation (interpolation) of representative constant-velocity extrapolated wavefields, with the number of these extrapolations controlled by the effective rank of the original mixed-domain operator or, more specifically, by the complexity of the velocity model. Conversely, with pseudo-spectral methods, because only the space derivatives are handled in the wavenumber domain, we obtain relatively efficient access to the inhomogeneity in isotropic media, but we often resort to weak approximations to handle the anisotropy efficiently. Utilizing perturbation theory, I isolate the contribution of anisotropy to the wavefield extrapolation process. This allows us to factorize as much of the inhomogeneity in the anisotropic parameters as possible out of the spectral implementation, yielding effectively a pseudo-spectral formulation. This is particularly true if the inhomogeneity of the dimensionless anisotropic parameters are mild compared with the velocity (i.e., factorized anisotropic media). I improve on the accuracy by using the Shanks transformation to incorporate a denominator in the expansion that predicts the higher-order omitted terms; thus, we deal with fewer terms for a high level of accuracy. In fact, when we use this new separation-based implementation, the anisotropy correction to the extrapolation can be applied separately as a residual operation, which provides a tool for anisotropic parameter sensitivity analysis. The accuracy of the approximation is high, as demonstrated in a complex tilted transversely isotropic model. © 2014 European Association of Geoscientists & Engineers.

  2. Metafluid with anisotropic dynamic mass

    International Nuclear Information System (INIS)

    Gumen, L.N.; Arriaga, J.; Krokhin, A.A.

    2011-01-01

    We show that a fluid filling the space between metallic cylinders arranged in a two-dimensional lattice exhibits anisotropic dynamic mass for sound waves propagating through the lattice, if its unit cell is anisotropic. Using the plane-waves expansion method we derive (in the long wavelength limit) a formula for the effective mass tensor of the metafluid. The proposed formula is very general - it is valid for arbitrary Bravais lattices and arbitrary filling fractions of the cylinders. We apply our method to a periodic structure with very high anisotropy, when other known methods fail. In particular, we calculate the effective mass tensor for sound waves in air with embedded lattice of aluminum cylinders having rectangular cross sections, and obtain excellent agreement with experiment. The proposed method of calculation may find numerous applications for tailoring of metafluids with prescribed anisotropy.

  3. Anisotropic Ripple Deformation in Phosphorene.

    Science.gov (United States)

    Kou, Liangzhi; Ma, Yandong; Smith, Sean C; Chen, Changfeng

    2015-05-07

    Two-dimensional materials tend to become crumpled according to the Mermin-Wagner theorem, and the resulting ripple deformation may significantly influence electronic properties as observed in graphene and MoS2. Here, we unveil by first-principles calculations a new, highly anisotropic ripple pattern in phosphorene, a monolayer black phosphorus, where compression-induced ripple deformation occurs only along the zigzag direction in the strain range up to 10%, but not the armchair direction. This direction-selective ripple deformation mode in phosphorene stems from its puckered structure with coupled hinge-like bonding configurations and the resulting anisotropic Poisson ratio. We also construct an analytical model using classical elasticity theory for ripple deformation in phosphorene under arbitrary strain. The present results offer new insights into the mechanisms governing the structural and electronic properties of phosphorene crucial to its device applications.

  4. Exact anisotropic polytropic cylindrical solutions

    Science.gov (United States)

    Sharif, M.; Sadiq, Sobia

    2018-03-01

    In this paper, we study anisotropic compact stars with static cylindrically symmetric anisotropic matter distribution satisfying polytropic equation of state. We formulate the field equations as well as the corresponding mass function for the particular form of gravitational potential z(x)=(1+bx)^{η } (η =1, 2, 3) and explore exact solutions of the field equations for different values of the polytropic index. The values of arbitrary constants are determined by taking mass and radius of compact star (Her X-1). We find that resulting solutions show viable behavior of physical parameters (density, radial as well as tangential pressure, anisotropy) and satisfy the stability condition. It is concluded that physically acceptable solutions exist only for η =1, 2.

  5. Inelastic neutron scattering investigation of magnetostructural excitations in the spin-Peierls organic system (TMTTF) 2P F6

    Science.gov (United States)

    Pouget, J. P.; Foury-Leylekian, P.; Petit, S.; Hennion, B.; Coulon, C.; Bourbonnais, C.

    2017-07-01

    One-dimensional (1D) conductors such as Bechgaard and Fabre salts are a prototypal example of correlated systems where the phase diagram is controlled by sizable electron-electron repulsions. In deuterated (TMTTF) 2P F6 , where this interaction achieves charge localization at ambient pressure on donor stacks, magnetostructural coupling plays a decisive role to stabilize a spin-Peierls (SPs) ground state at TSP=13 K . In this paper, we present the first inelastic neutron scattering investigation of SP magnetic excitations in organics. Our paper reveals the presence above TSP of sizable critical fluctuations leading to the formation of a pseudogap in the 1D antiferromagnetic (AF) S =1 /2 magnetic excitation spectrum of the donor stack, concomitant with the local formation of singlet of paired spins into dimers below TSPMF≈40 K . In addition, the inelastic neutron scattering investigation allows us also to probe the SP critical lattice dynamics and to show that at ambient pressure these dynamics are of relaxation or order-disorder type. Below TSP, our paper reveals the emergence of a two gap SP magnetic excitation spectrum towards a well-defined S =1 magnon mode and a continuum of two excitations, as theoretically predicted. Our measurements allow us to locate the ambient pressure SP phase of (TMTTF) 2P F6 in the classical (adiabatic) limit close to the classical/quantum crossover line. Then we provide arguments suggesting that pressurized (TMTTF) 2P F6 shifts to the quantum (antiadiabatic) SP gapped phase, which ends in a quantum critical point allowing the stabilization of an AF phase that competes with superconductivity at higher pressure. Finally, we propose that the magnetostructural coupling mechanism in the Fabre salts is caused by dimer charge/spin fluctuations driven by the coupling of donors with anions.

  6. Iron particle and anisotropic effects on mechanical properties of magneto-sensitive elastomers

    Science.gov (United States)

    Kumar, Vineet; Lee, Dong-Joo

    2017-11-01

    Rubber specimens were prepared by mixing micron-sized iron particles dispersed in room-temperature-vulcanized (RTV) silicone rubber by solution mixing. The possible correlations of the particle volume, size, and distribution with the mechanical properties of the specimens were examined. An isotropic mechanical test shows that at 60 phr, the elastic modulus was 3.29 MPa (electrolyte), 2.92 MPa (carbonyl), and 2.61 MPa (hybrid). The anisotropic effect was examined by curing the specimen under magnetic fields of 0.5-2.0 T at 90° relative to the applied strain. The measurements show anisotropic effects of 11% (carbonyl), 9% (electrolyte), and 6% (hybrid) at 40 phr and 1 T. At 80 phr, the polymer-filler compatibility factor (c-factor) was estimated using the Pythagorean theorem as 0.53 (regular) and 0.73 (anisotropic studies). The improved features could be useful in applications such as controlled damping, vibrational absorption, or automotive bushings.

  7. Anisotropic and nonlinear optical waveguides

    CERN Document Server

    Someda, CG

    1992-01-01

    Dielectric optical waveguides have been investigated for more than two decades. In the last ten years they have had the unique position of being simultaneously the backbone of a very practical and fully developed technology, as well as an extremely exciting area of basic, forefront research. Existing waveguides can be divided into two sets: one consisting of waveguides which are already in practical use, and the second of those which are still at the laboratory stage of their evolution. This book is divided into two separate parts: the first dealing with anisotropic waveguides, an

  8. Tunneling anisotropic magnetoresistance via molecular π orbitals of Pb dimers

    Science.gov (United States)

    Schöneberg, Johannes; Ferriani, Paolo; Heinze, Stefan; Weismann, Alexander; Berndt, Richard

    2018-01-01

    Pb dimers on a ferromagnetic surface are shown to exhibit large tunneling anisotropic magnetoresistance (TAMR) due to molecular π orbitals. Dimers oriented differently with respect to the magnetization directions of a ferromagnetic Fe double layer on W(110) were made with a scanning tunneling microscope. Depending on the dimer orientations, TAMR is absent or as large as 20% at the Fermi level. General arguments and first-principles calculations show that mixing of molecular orbitals due to spin-orbit coupling, which leads to TAMR, is maximal when the magnetization is oriented parallel to the dimer axis.

  9. Anisotropic non-Fermi liquids

    Science.gov (United States)

    Sur, Shouvik; Lee, Sung-Sik

    2016-11-01

    We study non-Fermi-liquid states that arise at the quantum critical points associated with the spin density wave (SDW) and charge density wave (CDW) transitions in metals with twofold rotational symmetry. We use the dimensional regularization scheme, where a one-dimensional Fermi surface is embedded in (3 -ɛ ) -dimensional momentum space. In three dimensions, quasilocal marginal Fermi liquids arise both at the SDW and CDW critical points: the speed of the collective mode along the ordering wave vector is logarithmically renormalized to zero compared to that of Fermi velocity. Below three dimensions, however, the SDW and CDW critical points exhibit drastically different behaviors. At the SDW critical point, a stable anisotropic non-Fermi-liquid state is realized for small ɛ , where not only time but also different spatial coordinates develop distinct anomalous dimensions. The non-Fermi liquid exhibits an emergent algebraic nesting as the patches of Fermi surface are deformed into a universal power-law shape near the hot spots. Due to the anisotropic scaling, the energy of incoherent spin fluctuations disperse with different power laws in different momentum directions. At the CDW critical point, on the other hand, the perturbative expansion breaks down immediately below three dimensions as the interaction renormalizes the speed of charge fluctuations to zero within a finite renormalization group scale through a two-loop effect. The difference originates from the fact that the vertex correction antiscreens the coupling at the SDW critical point whereas it screens at the CDW critical point.

  10. Reflection of light from an anisotropic medium

    OpenAIRE

    Ignatovich, Filipp V.; Ignatovich, Vladimir

    2010-01-01

    We present here a general approach to treat reflection and refraction of light of arbitrary polarization from single axis anisotropic plates. We show that reflection from interface inside the anisotropic medium is accompanied by beam splitting and can create surface waves.

  11. Mixed motion in deterministic ratchets due to anisotropic permeability

    NARCIS (Netherlands)

    Kulrattanarak, T.; Sman, van der R.G.M.; Lubbersen, Y.S.; Schroën, C.G.P.H.; Pham, H.T.M.; Sarro, P.M.; Boom, R.M.

    2011-01-01

    Nowadays microfluidic devices are becoming popular for cell/DNA sorting and fractionation. One class of these devices, namely deterministic ratchets, seems most promising for continuous fractionation applications of suspensions (Kulrattanarak et al., 2008 [1]). Next to the two main types of particle

  12. Effect of anisotropic plasticity on mixed mode interface crack growth

    DEFF Research Database (Denmark)

    Tvergaard, Viggo; Legarth, Brian Nyvang

    2007-01-01

    Crack growth along an interface between a solid with plastic anisotropy and an elastic substrate is modelled by representing the fracture process in terms of a traction–separation law specified on a crack plane. A phenomenological elastic–viscoplastic material model is applied, using one of two...... of the region analyzed. Crack growth resistance curves are calculated numerically, and based on these results the dependence of the steady-state fracture toughness on the near-tip mode mixity is determined. Different initial orientations of the principal axes relative to the interface are considered...

  13. Efficient Wavefield Extrapolation In Anisotropic Media

    KAUST Repository

    Alkhalifah, Tariq

    2014-07-03

    Various examples are provided for wavefield extrapolation in anisotropic media. In one example, among others, a method includes determining an effective isotropic velocity model and extrapolating an equivalent propagation of an anisotropic, poroelastic or viscoelastic wavefield. The effective isotropic velocity model can be based upon a kinematic geometrical representation of an anisotropic, poroelastic or viscoelastic wavefield. Extrapolating the equivalent propagation can use isotopic, acoustic or elastic operators based upon the determined effective isotropic velocity model. In another example, non-transitory computer readable medium stores an application that, when executed by processing circuitry, causes the processing circuitry to determine the effective isotropic velocity model and extrapolate the equivalent propagation of an anisotropic, poroelastic or viscoelastic wavefield. In another example, a system includes processing circuitry and an application configured to cause the system to determine the effective isotropic velocity model and extrapolate the equivalent propagation of an anisotropic, poroelastic or viscoelastic wavefield.

  14. Stability of anisotropic stellar filaments

    Science.gov (United States)

    Bhatti, M. Zaeem-ul-Haq; Yousaf, Z.

    2017-12-01

    The study of perturbation of self-gravitating celestial cylindrical object have been carried out in this paper. We have designed a framework to construct the collapse equation by formulating the modified field equations with the background of f(R , T) theory as well as dynamical equations from the contracted form of Bianchi identities with anisotropic matter configuration. We have encapsulated the radial perturbations on metric and material variables of the geometry with some known static profile at Newtonian and post-Newtonian regimes. We examined a strong dependence of unstable regions on stiffness parameter which measures the rigidity of the fluid. Also, the static profile and matter variables with f(R , T) dark source terms control the instability of compact cylindrical system.

  15. Warm anisotropic inflationary universe model

    International Nuclear Information System (INIS)

    Sharif, M.; Saleem, Rabia

    2014-01-01

    This paper is devoted to the study of warm inflation using vector fields in the background of a locally rotationally symmetric Bianchi type I model of the universe. We formulate the field equations, and slow-roll and perturbation parameters (scalar and tensor power spectra as well as their spectral indices) in the slow-roll approximation. We evaluate all these parameters in terms of the directional Hubble parameter during the intermediate and logamediate inflationary regimes by taking the dissipation factor as a function of the scalar field as well as a constant. In each case, we calculate the observational parameter of interest, i.e., the tensor-scalar ratio in terms of the inflaton. The graphical behavior of these parameters shows that the anisotropic model is also compatible with WMAP7 and the Planck observational data. (orig.)

  16. Warm anisotropic inflationary universe model

    Energy Technology Data Exchange (ETDEWEB)

    Sharif, M.; Saleem, Rabia [University of the Punjab, Department of Mathematics, Lahore (Pakistan)

    2014-02-15

    This paper is devoted to the study of warm inflation using vector fields in the background of a locally rotationally symmetric Bianchi type I model of the universe. We formulate the field equations, and slow-roll and perturbation parameters (scalar and tensor power spectra as well as their spectral indices) in the slow-roll approximation. We evaluate all these parameters in terms of the directional Hubble parameter during the intermediate and logamediate inflationary regimes by taking the dissipation factor as a function of the scalar field as well as a constant. In each case, we calculate the observational parameter of interest, i.e., the tensor-scalar ratio in terms of the inflaton. The graphical behavior of these parameters shows that the anisotropic model is also compatible with WMAP7 and the Planck observational data. (orig.)

  17. Anisotropic Magnus Force in Type-II Superconductors with Planar Defects

    Science.gov (United States)

    Monroy, Ricardo Vega; Gomez, Eliceo Cortés

    2015-02-01

    The effect of planar defects on the Magnus force in type-II superconductors is studied. It is shown that the deformation of the vortex due to the presence of a planar defect leads to a local decrease in the mean free path of electrons in the vortex. This effect reduces the effective Magnus coefficient in normal direction to the planar defect, leading to an anisotropic regime of the Hall effect. The presented developments here can qualitatively explain experimental observations of the anisotropic Hall effect in high- T c superconductors in the mixed state.

  18. Finite-volume scheme for anisotropic diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Es, Bram van, E-mail: bramiozo@gmail.com [Centrum Wiskunde & Informatica, P.O. Box 94079, 1090GB Amsterdam (Netherlands); FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, The Netherlands" 1 (Netherlands); Koren, Barry [Eindhoven University of Technology (Netherlands); Blank, Hugo J. de [FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, The Netherlands" 1 (Netherlands)

    2016-02-01

    In this paper, we apply a special finite-volume scheme, limited to smooth temperature distributions and Cartesian grids, to test the importance of connectivity of the finite volumes. The area of application is nuclear fusion plasma with field line aligned temperature gradients and extreme anisotropy. We apply the scheme to the anisotropic heat-conduction equation, and compare its results with those of existing finite-volume schemes for anisotropic diffusion. Also, we introduce a general model adaptation of the steady diffusion equation for extremely anisotropic diffusion problems with closed field lines.

  19. Viscous anisotropic hydrodynamics for the Gubser flow

    Science.gov (United States)

    Martinez, M.; McNelis, M.; Heinz, U.

    2017-11-01

    In this work we describe the dynamics of a highly anisotropic system undergoing boost-invariant longitudinal and azimuthally symmetric radial expansion (Gubser flow) for arbitrary shear viscosity to entropy density ratio. We derive the equations of motion of dissipative anisotropic hydrodynamics by applying to this situation the moments method recently derived by Molnár et al. (MNR) [E. Molnar, H. Niemi, and D. H. Rischke, "Derivation of anisotropic dissipative fluid dynamics from the Boltzmann equation," Phys. Rev. D93 no. 11, (2016) 114025, arxiv:arXiv:1602.00573 [nucl-th], E. Molnar, H. Niemi, and D. H. Rischke, "Closing the equations of motion of anisotropic fluid dynamics by a judicious choice of a moment of the Boltzmann equation," Phys. Rev. D94 no. 12, (2016) 125003, arxiv:arXiv:1606.09019 [nucl-th

  20. Anisotropic magnetoresistance in a Fermi glass

    International Nuclear Information System (INIS)

    Ovadyahu, Z.; Physics Department, Ben-Gurion University of the Negev, Beer-Sheva, Israel 84120)

    1986-01-01

    Insulating thin films of indium oxide exhibit negative, anisotropic magnetoresistance. The systematics of these results imply that the magnetoresistance mechanism may give different weight to the distribution of the localization lengths than that given by the hopping conductivity

  1. Modelling Coulomb Collisions in Anisotropic Plasmas

    Science.gov (United States)

    Hellinger, P.; Travnicek, P. M.

    2009-12-01

    Collisional transport in anisotropic plasmas is investigated comparing the theoretical transport coefficients (Hellinger and Travnicek, 2009) for anisotropic particles with the results of the corresponding Langevin equation, obtained as a generalization of Manheimer et al. (1997). References: Hellinger, P., and P. M. Travnicek (2009), On Coulomb collisions in bi-Maxwellian plasmas, Phys. Plasmas, 16, 054501. Manheimer, W. M., M. Lampe and G. Joyce (1997), Langevin representation of Coulomb collisions in PIC simulations, J. Comput. Phys., 138, 563-584.

  2. Anisotropic rectangular metric for polygonal surface remeshing

    KAUST Repository

    Pellenard, Bertrand

    2013-06-18

    We propose a new method for anisotropic polygonal surface remeshing. Our algorithm takes as input a surface triangle mesh. An anisotropic rectangular metric, defined at each triangle facet of the input mesh, is derived from both a user-specified normal-based tolerance error and the requirement to favor rectangle-shaped polygons. Our algorithm uses a greedy optimization procedure that adds, deletes and relocates generators so as to match two criteria related to partitioning and conformity.

  3. Penetration effect in uniaxial anisotropic metamaterials

    Science.gov (United States)

    Vytovtov, K.; Barabanova, E.; Zouhdi, S.

    2018-02-01

    Plane harmonic wave propagation along an interface between vacuum and a semi-infinite anisotropic metamaterial is considered. Possibility of penetration effect in the considered case is studied. It is shown that there is a bulk wave within the anisotropic metamaterial with an arbitrary orientation of the anisotropy axis. It is also proved that a reflected wave must propagate perpendicularly to the interface in the case of the extraordinary wave. Moreover, no wave is reflected in the case of ordinary wave propagation.

  4. An anisotropic elastoplasticity model implemented in FLAG

    Energy Technology Data Exchange (ETDEWEB)

    Buechler, Miles Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Canfield, Thomas R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-12

    Many metals, including Tantalum and Zirconium, exhibit anisotropic elastoplastic behavior at the single crystal level, and if components are manufactured from these metals through forming processes the polycrystal (component) may also exhibit anisotropic elastoplastic behavior. This is because the forming can induce a preferential orientation of the crystals in the polycrystal. One example is a rolled plate of Uranium where the sti /strong orientation of the crystal (c-axis) tends to align itself perpendicular to the rolling direction. If loads are applied to this plate in di erent orientations the sti ness as well as the ow strength of the material will be greater in the through thickness direction than in other directions. To better accommodate simulations of such materials, an anisotropic elastoplasticity model has been implemented in FLAG. The model includes an anisotropic elastic stress model as well as an anisotropic plasticity model. The model could represent single crystals of any symmetry, though it should not be confused with a high- delity crystal plasticity model with multiple slip planes and evolutions. The model is most appropriate for homogenized polycrystalline materials. Elastic rotation of the material due to deformation is captured, so the anisotropic models are appropriate for arbitrary large rotations, but currently they do not account for signi cant change in material texture beyond the elastic rotation of the entire polycrystal.

  5. Mechanics of anisotropic spring networks.

    Science.gov (United States)

    Zhang, T; Schwarz, J M; Das, Moumita

    2014-12-01

    We construct and analyze a model for a disordered linear spring network with anisotropy. The modeling is motivated by, for example, granular systems, nematic elastomers, and ultimately cytoskeletal networks exhibiting some underlying anisotropy. The model consists of a triangular lattice with two different bond occupation probabilities, p(x) and p(y), for the linear springs. We develop an effective medium theory (EMT) to describe the network elasticity as a function of p(x) and p(y). We find that the onset of rigidity in the EMT agrees with Maxwell constraint counting. We also find beyond linear behavior in the shear and bulk modulus as a function of occupation probability in the rigid phase for small strains, which differs from the isotropic case. We compare our EMT with numerical simulations to find rather good agreement. Finally, we discuss the implications of extending the reach of effective medium theory as well as draw connections with prior work on both anisotropic and isotropic spring networks.

  6. Rotational discontinuities in anisotropic plasmas

    International Nuclear Information System (INIS)

    Omidi, N.

    1992-01-01

    The kinetic structure of rotational discontinuities (RDs) in anisotropic plasmas with T perpendicular /T parallel > 1 is investigated by using a one-dimensional electromagnetic hybrid code. To form the RD, a new approach is used where the plasma is injected from one boundary and reflected from the other, resulting in the generation of a traveling fast shock and an RD. Unlike the previously used methods, no a priori assumptions are made regarding the initial structure (i.e. width or sense of rotation) of the rotational discontinuity. The results show that across the RD both the magnetic field strength and direction, as well as the plasma density change. Given that such a change can also be associated with an intermediate shock, the Rankine-Hugoniot relations are used to confirm that the observed structures are indeed RDs. It is found that the thickness of RDs is a few ion inertial lengths and is independent of the rotation angle. Also, the preferred sense of rotation is in the electron sense; however, RDs with a rotation angle larger than 180 degree are found to be unstable, changing their rotation to a stable ion sense

  7. Flow shapes and higher harmonics in anisotropic transverse collective flow

    Energy Technology Data Exchange (ETDEWEB)

    Argintaru, Danut; Baban, Valerica [Constanta Maritime University, Faculty of Navigation and Naval Transport, Constanta (Romania); Besliu, Calin; Jipa, Alexandru; Grossu, Valeriu [University of Bucharest, Faculty of Physics, Bucharest (Romania); Esanu, Tiberiu; Cherciu, Madalin [Institute of Space Sciences Bucharest-Magurele, Bucharest (Romania)

    2017-01-15

    In this paper we show that by using a jet-finder algorithm (the Anti-k{sub T} one) on UrQMD/C simulated (Au+Au at 4, 10 and 15A GeV) collisions, we can identify different flow shape structures (single flow stream events, two flow streams events, three flow streams events, etc.) and order the bulk of events in equivalence flow shape classes. Considering these flow streams as the main directions of anisotropic transverse flow, we show that the Fourier coefficients v{sub n} of anisotropic flow are better emphasized when we analyze the different event flow shape classes than when the events are mixed. Also, if we do not know the real orientation of the reaction plane, we can use as reference the Flow stream 1 - the main particle flow stream - orientation (Ψ{sub Flowstream} {sub 1}) to highlight the initial shape of the participant nuclear matter in a central to peripheral collision, and the orientation of the participant plane of order n. (orig.)

  8. Anisotropic nanomaterials: structure, growth, assembly, and functions

    Science.gov (United States)

    Sajanlal, Panikkanvalappil R.; Sreeprasad, Theruvakkattil S.; Samal, Akshaya K.; Pradeep, Thalappil

    2011-01-01

    Comprehensive knowledge over the shape of nanomaterials is a critical factor in designing devices with desired functions. Due to this reason, systematic efforts have been made to synthesize materials of diverse shape in the nanoscale regime. Anisotropic nanomaterials are a class of materials in which their properties are direction-dependent and more than one structural parameter is needed to describe them. Their unique and fine-tuned physical and chemical properties make them ideal candidates for devising new applications. In addition, the assembly of ordered one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) arrays of anisotropic nanoparticles brings novel properties into the resulting system, which would be entirely different from the properties of individual nanoparticles. This review presents an overview of current research in the area of anisotropic nanomaterials in general and noble metal nanoparticles in particular. We begin with an introduction to the advancements in this area followed by general aspects of the growth of anisotropic nanoparticles. Then we describe several important synthetic protocols for making anisotropic nanomaterials, followed by a summary of their assemblies, and conclude with major applications. PMID:22110867

  9. Effective medium theory for anisotropic metamaterials

    KAUST Repository

    Zhang, Xiujuan

    2015-01-20

    Materials with anisotropic material parameters can be utilized to fabricate many fascinating devices, such as hyperlenses, metasolids, and one-way waveguides. In this study, we analyze the effects of geometric anisotropy on a two-dimensional metamaterial composed of a rectangular array of elliptic cylinders and derive an effective medium theory for such a metamaterial. We find that it is possible to obtain a closed-form analytical solution for the anisotropic effective medium parameters, provided the aspect ratio of the lattice and the eccentricity of the elliptic cylinder satisfy certain conditions. The derived effective medium theory not only recovers the well-known Maxwell-Garnett results in the quasi-static regime, but is also valid beyond the long-wavelength limit, where the wavelength in the host medium is comparable to the size of the lattice so that previous anisotropic effective medium theories fail. Such an advance greatly broadens the applicable realm of the effective medium theory and introduces many possibilities in the design of structures with desired anisotropic material characteristics. A real sample of a recently theoretically proposed anisotropic medium, with a near-zero index to control the flux, is achieved using the derived effective medium theory, and control of the electromagnetic waves in the sample is clearly demonstrated.

  10. Head-wave coefficients in anisotropic media

    Science.gov (United States)

    Chapman, Chris

    2018-03-01

    Reflections and transmissions from interfaces can generate head waves. Although the kinematic properties of head waves are modelled simply using ray concepts, the dynamic properties require an extension of ray theory or the use of wave theory. Head waves are important in exploration and crustal seismology as they indicate the existence of an interface and the velocity of the generating wave. Head waves have been described in the literature for isotropic media but the extension to anisotropic media seems to be lacking. The expressions for the head-wave coefficients using ray concepts or wave theory differ, and their equality is not obvious. This paper extends the theory for head-wave coefficients to anisotropic media using both ray theory and wave theory, and generalizes the proof of equality of the two methods. Simple numerical examples confirm this equality and indicate how the head-wave results can be calculated in anisotropic media and included in a ray-tracing algorithm.

  11. Elastic properties of spherically anisotropic piezoelectric composites

    International Nuclear Information System (INIS)

    En-Bo, Wei; Guo-Qing, Gu; Ying-Ming, Poon

    2010-01-01

    Effective elastic properties of spherically anisotropic piezoelectric composites, whose spherically anisotropic piezoelectric inclusions are embedded in an infinite non-piezoelectric matrix, are theoretically investigated. Analytical solutions for the elastic displacements and the electric potentials under a uniform external strain are derived exactly. Taking into account of the coupling effects of elasticity, permittivity and piezoelectricity, the formula is derived for estimating the effective elastic properties based on the average field theory in the dilute limit. An elastic response mechanism is revealed, in which the effective elastic properties increase as inclusion piezoelectric properties increase and inclusion dielectric properties decrease. Moreover, a piezoelectric response mechanism, of which the effective piezoelectric response vanishes due to the symmetry of spherically anisotropic composite, is also disclosed. (condensed matter: structure, thermal and mechanical properties)

  12. Obtuse triangle suppression in anisotropic meshes

    KAUST Repository

    Sun, Feng

    2011-12-01

    Anisotropic triangle meshes are used for efficient approximation of surfaces and flow data in finite element analysis, and in these applications it is desirable to have as few obtuse triangles as possible to reduce the discretization error. We present a variational approach to suppressing obtuse triangles in anisotropic meshes. Specifically, we introduce a hexagonal Minkowski metric, which is sensitive to triangle orientation, to give a new formulation of the centroidal Voronoi tessellation (CVT) method. Furthermore, we prove several relevant properties of the CVT method with the newly introduced metric. Experiments show that our algorithm produces anisotropic meshes with much fewer obtuse triangles than using existing methods while maintaining mesh anisotropy. © 2011 Elsevier B.V. All rights reserved.

  13. Generalized Fractional Derivative Anisotropic Viscoelastic Characterization

    Directory of Open Access Journals (Sweden)

    Harry H. Hilton

    2012-01-01

    Full Text Available Isotropic linear and nonlinear fractional derivative constitutive relations are formulated and examined in terms of many parameter generalized Kelvin models and are analytically extended to cover general anisotropic homogeneous or non-homogeneous as well as functionally graded viscoelastic material behavior. Equivalent integral constitutive relations, which are computationally more powerful, are derived from fractional differential ones and the associated anisotropic temperature-moisture-degree-of-cure shift functions and reduced times are established. Approximate Fourier transform inversions for fractional derivative relations are formulated and their accuracy is evaluated. The efficacy of integer and fractional derivative constitutive relations is compared and the preferential use of either characterization in analyzing isotropic and anisotropic real materials must be examined on a case-by-case basis. Approximate protocols for curve fitting analytical fractional derivative results to experimental data are formulated and evaluated.

  14. Crack’s bifurcation in an anisotropic material

    Directory of Open Access Journals (Sweden)

    El Kaaba A.

    2012-07-01

    Full Text Available The orthotropic of a solid is characterized by the material directions 1→,2→,3→$mathop 1limits^ o ,mathop 2limits^ o ,mathop 3limits^ o $ and corresponds to six main directions of the crack’ distribution 21, 31, 32, 12, 13 and 23 (the first number corresponds to the normal of the crack’s plan, the second in the crack’s front. In this work, it was suggested studying the crack’s bifurcation solicited in the mixed mode of an anisotropic fracture’s specimen by varying several geometrical parameters. The study showed that the critical angle of bifurcation depends on the crack’s length, the specimen’s height, the angle of load as well as on the chosen configuration.

  15. Nuclear quadrupole deformations and anisotropic angular correlations between K x rays and gamma rays

    International Nuclear Information System (INIS)

    Khalil, A.E.

    1983-01-01

    Anisotropic angular correlation between gamma rays and the K x rays following the K conversion from nuclei with large static deformations has been studied. A complete theoretical expression for 181 Ta, the second known case of this phenomenon, is presented. This case involves several mixed nuclear transitions which result in 62% of the x rays arising from magnetic dipole internal-conversion processes and 38% arising from electric-quadrupole internal-conversion processes

  16. Anisotropic nanomaterials preparation, properties, and applications

    CERN Document Server

    Li, Quan

    2015-01-01

    In this book anisotropic one-dimensional and two-dimensional nanoscale building blocks and their assembly into fascinating and qualitatively new functional structures embracing both hard and soft components are explained. Contributions from leading experts regarding important aspects like synthesis, assembly, properties and applications of the above materials are compiled into a reference book. The anisotropy, i.e. the direction-dependent physical properties, of materials is fascinating and elegant and has sparked the quest for anisotropic materials with useful properties. With such a curiosi

  17. Modelling of CMUTs with Anisotropic Plates

    DEFF Research Database (Denmark)

    la Cour, Mette Funding; Christiansen, Thomas Lehrmann; Jensen, Jørgen Arendt

    2012-01-01

    Traditionally, CMUTs are modelled using the isotropic plate equation and this leads to deviations between analytical calculations and FEM simulations. In this paper, the deflection profile and material parameters are calculated using the anisotropic plate equation. It is shown that the anisotropic...... calculations match perfectly with FEM while an isotropic approach causes up to 10% deviations in deflection profile. Furthermore, we show how commonly used analytic modelling methods such as static calculations of the pull-in voltage and dynamic modelling through an equivalent circuit representation can...

  18. A Variational Approach to Perturbed Discrete Anisotropic Equations

    Directory of Open Access Journals (Sweden)

    Amjad Salari

    2016-01-01

    Full Text Available We continue the study of discrete anisotropic equations and we will provide new multiplicity results of the solutions for a discrete anisotropic equation. We investigate the existence of infinitely many solutions for a perturbed discrete anisotropic boundary value problem. The approach is based on variational methods and critical point theory.

  19. The Effect of Anisotropic Scatter on Atmospheric Neutron Transport

    Science.gov (United States)

    2015-03-26

    THE EFFECT OF ANISOTROPIC SCATTER ON ATMOSPHERIC NEUTRON TRANSPORT THESIS MARCH 2015 Nicholas J...iii AFIT-ENP-MS-15-M-085 THE EFFECT OF ANISOTROPIC SCATTER ON ATMOSPHERIC NEUTRON TRANSPORT THESIS Presented to the...EFFECT OF ANISOTROPIC SCATTER ON ATMOSPHERIC NEUTRON TRANSPORT Nicholas J. McIntee, BSE Major, USA Committee Membership: Dr. Kirk A. Mathews

  20. Hypersurface-homogeneous cosmological models with anisotropic ...

    Indian Academy of Sciences (India)

    2016-12-05

    Dec 5, 2016 ... DOI 10.1007/s12043-016-1317-4. Hypersurface-homogeneous cosmological models with anisotropic dark energy in Saez–Ballester theory of gravitation. M K VERMA1, S CHANDEL2 and SHRI RAM2,∗. 1Department of Mathematics, Baba Banarasi Das National Institute of Technology & Management,.

  1. Anisotropic Hanle line shape via magnetothermoelectric phenomena

    NARCIS (Netherlands)

    Das, Kumar; Dejene, Fasil; van Wees, Bart; Vera Marun, Ivan

    2016-01-01

    We observe anisotropic Hanle line shape with unequal in-plane and out-of-plane nonlocal signals for spin precession measurements carried out on lateral metallic spin valves with transparent interfaces. The conventional interpretation for this anisotropy corresponds to unequal spin relaxation times

  2. Adaptive slices for acquisition of anisotropic BRDF

    Czech Academy of Sciences Publication Activity Database

    Vávra, Radomír; Filip, Jiří

    (2018) ISSN 2096-0433 R&D Projects: GA ČR GA17-18407S Institutional support: RVO:67985556 Keywords : anisotropic BRDF * slice * sampling Subject RIV: BD - Theory of Information http://library.utia.cas.cz/separaty/2018/RO/vavra-0486116.pdf

  3. Theory of anisotropic diamagnetism, local moment magnetization ...

    Indian Academy of Sciences (India)

    Theory of anisotropic diamagnetism, local moment magnetization and carrier spin-polarization in Pb1-EuTe ... Gopalpur 761 002, India; Department of Physics, Jagannath Institute for Technology and Management, Parlakhemundi 761 211, India; Department of Physics, Berhampur University, Berhampur 760 007, India ...

  4. Hypersurface-homogeneous cosmological models with anisotropic ...

    Indian Academy of Sciences (India)

    The present study deals with hypersurface-homogeneous cosmological models with anisotropic dark energy in Saez–Ballester theory of gravitation. Exact solutions of field equations are obtained by applying a special law of variation of Hubble's parameter that yields a constant negative value of the deceleration parameter.

  5. Minimally coupled scalar field cosmology in anisotropic ...

    Indian Academy of Sciences (India)

    We study a spatially homogeneous and anisotropic cosmological model in the Einstein gravitational theory with a minimally coupled scalar field. We consider a non-interacting combination of scalar field and perfect fluid as the source of matter components which are separately conserved. The dynamics of cosmic scalar ...

  6. Algebraic solution of an anisotropic nonquadratic potential

    International Nuclear Information System (INIS)

    Boschi Filho, H.; Vaidya, A.N.

    1990-06-01

    We show that an anisotropic nonquadratic potential, for which a path integral treatment had been recently discussed in the literature, possesses the (SO(2,1)xSO(2,1))ΛSO(2,1) dynamical symmetry and constructs its Green function algebraically. A particular case which generates new eigenvalues and eigenfunctions is also discussed. (author). 11 refs

  7. Modelling anisotropic water transport in polymer composite

    Indian Academy of Sciences (India)

    This work reports anisotropic water transport in a polymer composite consisting of an epoxy matrix reinforced with aligned triangular bars made of vinyl ester. By gravimetric experiments, water diffusion in resin and polymer composites were characterized. Parameters for Fickian diffusion and polymer relaxation models were ...

  8. A new algorithm for anisotropic solutions

    Indian Academy of Sciences (India)

    We establish a new algorithm that generates a new solution to the Einstein field equations, with an anisotropic matter distribution, from a seed isotropic solution. The new solution is expressed in terms of integrals of an isotropic gravitational potential; and the integration can be completed exactly for particular isotropic seed ...

  9. Acoustic reflection from the boundary of anisotropic ...

    Indian Academy of Sciences (India)

    Vertical slownesses of waves at a boundary of an anisotropic thermoviscoelastic medium are calculated as roots of a polynomial equation of degree eight. Out of the corresponding eight waves, the four, which travel towards the boundary are identified as upgoing waves. Remaining four waves travel away from the boundary ...

  10. Ray tracing in anisotropic media with singularities

    Czech Academy of Sciences Publication Activity Database

    Vavryčuk, Václav

    2001-01-01

    Roč. 145, č. 1 (2001), s. 265-276 ISSN 0956-540X R&D Projects: GA ČR GA205/00/1350 Institutional research plan: CEZ:AV0Z3012916 Keywords : anisotropic media * ray tracing * singularities Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.366, year: 2001

  11. Minimally coupled scalar field cosmology in anisotropic ...

    Indian Academy of Sciences (India)

    2017-01-03

    Jan 3, 2017 ... a phantom field [24,25], quintom [26,27], k-essence. [28], tachyon [29] and so forth. It is well known that the evolution of the Uni- verse admits a scenario of anisotropic expansion and gains a lot of interest, under the light of the recently announced Planck Probe results [7]. The Bianchi models, which describe ...

  12. Modelling anisotropic water transport in polymer composite ...

    Indian Academy of Sciences (India)

    Abstract. This work reports anisotropic water transport in a polymer composite consisting of an epoxy matrix reinforced with aligned triangular bars made of vinyl ester. By gravimetric experiments, water diffusion in resin and polymer composites were characterized. Parameters for Fickian diffusion and polymer relaxation ...

  13. The method of images for anisotropic media

    International Nuclear Information System (INIS)

    Iosilevskii, Ya.A.

    1978-01-01

    The method of images is suggested to construct a scalar macroscopic field (dynamic or static) of a point source in an anisotropic half-space or flat slab. The field is found for an arbitrary orientation of the boundaries with respect to the crystallographic axes. (Auth.)

  14. Anisotropic power-law k-inflation

    Science.gov (United States)

    Ohashi, Junko; Soda, Jiro; Tsujikawa, Shinji

    2013-11-01

    It is known that power-law k-inflation can be realized for the Lagrangian P=Xg(Y), where X=-(∂ϕ)2/2 is the kinetic energy of a scalar field ϕ and g is an arbitrary function in terms of Y=Xeλϕ/Mpl (λ is a constant and Mpl is the reduced Planck mass). In the presence of a vector field coupled to the inflaton with an exponential coupling f(ϕ)∝eμϕ/Mpl, we show that the models with the Lagrangian P=Xg(Y) generally give rise to anisotropic inflationary solutions with Σ/H=constant, where Σ is an anisotropic shear and H is an isotropic expansion rate. Provided these anisotropic solutions exist in the regime where the ratio Σ/H is much smaller than 1, they are stable attractors irrespective of the forms of g(Y). We apply our results to concrete models of k-inflation such as the generalized dilatonic ghost condensate and the Dirac-Born-Infeld model and we numerically show that the solutions with different initial conditions converge to the anisotropic power-law inflationary attractors. Even in the de Sitter limit (λ→0) such solutions can exist, but in this case the null energy condition is generally violated. The latter property is consistent with the Wald’s cosmic conjecture stating that the anisotropic hair does not survive on the de Sitter background in the presence of matter respecting the dominant/strong energy conditions.

  15. Views on the Anisotropic Nature of Ilva Valley Region

    Directory of Open Access Journals (Sweden)

    GABRIELA-ALINA MUREŞAN

    2012-01-01

    Full Text Available There are two concepts important for the authors of this article: anisotropic region and anisotropic space. Anisotropic region is defined by A. Dauphiné, the geographer (-mathematician, as a territorial unit whose structure results from the organisation of space along one or more axes. From the point of view of a territorial system, this type of region has some characteristics which differentiate it both from the homogeneous region and from the polarised one. These specificities have been analysed for Ilva Valley. The region of Ilva Valley is formed along the morphological axis represented by the Ilva River. The aim is to identify these specificities or their absence within this region. In this way we can determine whether this region is an anisotropic one or just an anisotropic space, namely whether it can be considered as evolving towards an anisotropic region, not yet complying with all characteristics of anisotropic regions.

  16. A multipoint flux approximation of the steady-state heat conduction equation in anisotropic media

    KAUST Repository

    Salama, Amgad

    2013-03-20

    In this work, we introduce multipoint flux (MF) approximation method to the problem of conduction heat transfer in anisotropic media. In such media, the heat flux vector is no longer coincident with the temperature gradient vector. In this case, thermal conductivity is described as a second order tensor that usually requires, at least, six quantities to be fully defined in general three-dimensional problems. The two-point flux finite differences approximation may not handle such anisotropy and essentially more points need to be involved to describe the heat flux vector. In the framework of mixed finite element method (MFE), the MFMFE methods are locally conservative with continuous normal fluxes. We consider the lowest order Brezzi-Douglas-Marini (BDM) mixed finite element method with a special quadrature rule that allows for nodal velocity elimination resulting in a cell-centered system for the temperature. We show comparisons with some analytical solution of the problem of conduction heat transfer in anisotropic long strip. We also consider the problem of heat conduction in a bounded, rectangular domain with different anisotropy scenarios. It is noticed that the temperature field is significantly affected by such anisotropy scenarios. Also, the technique used in this work has shown that it is possible to use the finite difference settings to handle heat transfer in anisotropic media. In this case, heat flux vectors, for the case of rectangular mesh, generally require six points to be described. Copyright © 2013 by ASME.

  17. Cosmological signatures of anisotropic spatial curvature

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Thiago S. [Departamento de Física, Universidade Estadual de Londrina, 86057-970, Londrina – PR (Brazil); Marugán, Guillermo A. Mena [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006, Madrid (Spain); Carneiro, Saulo, E-mail: tspereira@uel.br, E-mail: mena@iem.cfmac.csic.es, E-mail: saulo.carneiro@pq.cnpq.br [Instituto de Física, Universidade Federal da Bahia, 40210-340, Salvador – BA (Brazil)

    2015-07-01

    If one is willing to give up the cherished hypothesis of spatial isotropy, many interesting cosmological models can be developed beyond the simple anisotropically expanding scenarios. One interesting possibility is presented by shear-free models in which the anisotropy emerges at the level of the curvature of the homogeneous spatial sections, whereas the expansion is dictated by a single scale factor. We show that such models represent viable alternatives to describe the large-scale structure of the inflationary universe, leading to a kinematically equivalent Sachs-Wolfe effect. Through the definition of a complete set of spatial eigenfunctions we compute the two-point correlation function of scalar perturbations in these models. In addition, we show how such scenarios would modify the spectrum of the CMB assuming that the observations take place in a small patch of a universe with anisotropic curvature.

  18. Equilibrium-Based Nonhomogeneous Anisotropic Beam Element

    DEFF Research Database (Denmark)

    Krenk, Steen; Couturier, Philippe

    2017-01-01

    The stiffness matrix and the nodal forces associated with distributed loads are obtained for a nonhomogeneous anisotropic elastic beam element by the use of complementary energy. The element flexibility matrix is obtained by integrating the complementary-energy density corresponding to six beam...... equilibrium states, and then inverted and expanded to provide the element-stiffness matrix. Distributed element loads are represented via corresponding internal-force distributions in local equilibrium with the loads. The element formulation does not depend on assumed shape functions and can, in principle......, include any variation of cross-sectional properties and load variation, provided that these are integrated with sufficient accuracy in the process. The ability to represent variable cross-sectional properties, coupling from anisotropic materials, and distributed element loads is illustrated by numerical...

  19. Polar Functions for Anisotropic Gaussian Random Fields

    Directory of Open Access Journals (Sweden)

    Zhenlong Chen

    2014-01-01

    Full Text Available Let X be an (N, d-anisotropic Gaussian random field. Under some general conditions on X, we establish a relationship between a class of continuous functions satisfying the Lipschitz condition and a class of polar functions of X. We prove upper and lower bounds for the intersection probability for a nonpolar function and X in terms of Hausdorff measure and capacity, respectively. We also determine the Hausdorff and packing dimensions of the times set for a nonpolar function intersecting X. The class of Gaussian random fields that satisfy our conditions includes not only fractional Brownian motion and the Brownian sheet, but also such anisotropic fields as fractional Brownian sheets, solutions to stochastic heat equation driven by space-time white noise, and the operator-scaling Gaussian random field with stationary increments.

  20. Wireless energy transfer between anisotropic metamaterials shells

    Energy Technology Data Exchange (ETDEWEB)

    Díaz-Rubio, Ana; Carbonell, Jorge; Sánchez-Dehesa, José, E-mail: jsdehesa@upv.es

    2014-06-15

    The behavior of strongly coupled Radial Photonic Crystals shells is investigated as a potential alternative to transfer electromagnetic energy wirelessly. These sub-wavelength resonant microstructures, which are based on anisotropic metamaterials, can produce efficient coupling phenomena due to their high quality factor. A configuration of selected constitutive parameters (permittivity and permeability) is analyzed in terms of its resonant characteristics. The coupling to loss ratio between two coupled resonators is calculated as a function of distance, the maximum (in excess of 300) is obtained when the shells are separated by three times their radius. Under practical conditions an 83% of maximum power transfer has been also estimated. -- Highlights: •Anisotropic metamaterial shells exhibit high quality factors and sub-wavelength size. •Exchange of electromagnetic energy between shells with high efficiency is analyzed. •Strong coupling is supported with high wireless transfer efficiency. •End-to-end energy transfer efficiencies higher than 83% can be predicted.

  1. The shear viscosity in anisotropic phases

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Sachin [Department of Physics, Cornell University,Ithaca, New York 14853 (United States); Samanta, Rickmoy; Trivedi, Sandip P. [Department of Theoretical Physics, Tata Institute of Fundamental Research,Colaba, Mumbai 400005 (India)

    2015-10-06

    We construct anisotropic black brane solutions and analyse the behaviour of some of their metric perturbations. These solutions correspond to field theory duals in which rotational symmetry is broken due an externally applied, spatially constant, force. We find, in several examples, that when the anisotropy is sufficiently big compared to the temperature, some components of the viscosity tensor can become very small in units of the entropy density, parametrically violating the KSS bound. We obtain an expression relating these components of the viscosity, in units of the entropy density, to a ratio of metric components at the horizon of the black brane. This relation is generally valid, as long as the forcing function is translationally invariant, and it directly connects the parametric violation of the bound to the anisotropy in the metric at the horizon. Our results suggest the possibility that such small components of the viscosity tensor might also arise in anisotropic strongly coupled fluids found in nature.

  2. Anisotropic instability of a stretching film

    Science.gov (United States)

    Xu, Bingrui; Li, Minhao; Deng, Daosheng

    2017-11-01

    Instability of a thin liquid film, such as dewetting arising from Van der Waals force, has been well studied, and is typically characterized by formation of many droplets. Interestingly, a thin liquid film subjected to an applied stretching during a process of thermal drawing is evolved into an array of filaments, i.e., continuity is preserved along the direction of stretching while breakup occurs exclusively in the plane of cross section. Here, to understand this anisotropic instability, we build a physical model by considering both Van der Waals force and the effect of stretching. By using the linear instability analysis method and then performing a numerical calculation, we find that the growth rate of perturbations at the cross section is larger than that along the direction of stretching, resulting in the anisotropic instability of the stretching film. These results may provide theoretical guidance to achieve more diverse structures for nanotechnology.

  3. Anisotropic N=4 Super-Yang-Mills Plasma and Its Instabilities

    Science.gov (United States)

    Mateos, David; Trancanelli, Diego

    2011-09-01

    We present a type-IIB supergravity solution dual to a spatially anisotropic finite-temperature N=4 super-Yang-Mills plasma. The solution is static and completely regular. The full geometry can be viewed as a renormalization group flow from an ultraviolet anti-de Sitter geometry to an infrared Lifshitz-like geometry. The anisotropy can be equivalently understood as resulting from a position-dependent θ term or from a nonzero number density of dissolved D7-branes. The holographic stress tensor is conserved and anisotropic. The presence of a conformal anomaly plays an important role in the thermodynamics. The phase diagram exhibits homogeneous and inhomogeneous (i.e., mixed) phases. In some regions the homogeneous phase displays instabilities reminiscent of those of weakly coupled plasmas. We comment on similarities with QCD at finite baryon density and with the phenomenon of cavitation.

  4. Anisotropic N=4 super-Yang-Mills plasma and its instabilities.

    Science.gov (United States)

    Mateos, David; Trancanelli, Diego

    2011-09-02

    We present a type-IIB supergravity solution dual to a spatially anisotropic finite-temperature N=4 super-Yang-Mills plasma. The solution is static and completely regular. The full geometry can be viewed as a renormalization group flow from an ultraviolet anti-de Sitter geometry to an infrared Lifshitz-like geometry. The anisotropy can be equivalently understood as resulting from a position-dependent θ term or from a nonzero number density of dissolved D7-branes. The holographic stress tensor is conserved and anisotropic. The presence of a conformal anomaly plays an important role in the thermodynamics. The phase diagram exhibits homogeneous and inhomogeneous (i.e., mixed) phases. In some regions the homogeneous phase displays instabilities reminiscent of those of weakly coupled plasmas. We comment on similarities with QCD at finite baryon density and with the phenomenon of cavitation.

  5. Anisotropic magnetocapacitance in ferromagnetic-plate capacitors

    Science.gov (United States)

    Haigh, J. A.; Ciccarelli, C.; Betz, A. C.; Irvine, A.; Novák, V.; Jungwirth, T.; Wunderlich, J.

    2015-04-01

    The capacitance of a parallel-plate capacitor can depend on the applied magnetic field. Previous studies have identified capacitance changes induced via classical Lorentz force or spin-dependent Zeeman effects. Here we measure a magnetization direction-dependent capacitance in parallel-plate capacitors where one plate is a ferromagnetic semiconductor, gallium manganese arsenide. This anisotropic magnetocapacitance is due to the anisotropy in the density of states dependent on the magnetization through the strong spin-orbit interaction.

  6. Symmetry analysis for anisotropic field theories

    International Nuclear Information System (INIS)

    Parra, Lorena; Vergara, J. David

    2012-01-01

    The purpose of this paper is to study with the help of Noether's theorem the symmetries of anisotropic actions for arbitrary fields which generally depend on higher order spatial derivatives, and to find the corresponding current densities and the Noether charges. We study in particular scale invariance and consider the cases of higher derivative extensions of the scalar field, electrodynamics and Chern-Simons theory.

  7. Anisotropic diffusion tensor applied to temporal mammograms

    DEFF Research Database (Denmark)

    Karemore, Gopal; Brandt, Sami; Sporring, Jon

    2010-01-01

    changes related to  specific  effects  like  Hormonal  Replacement  Therapy  (HRT) and aging. Given effect-grouped patient data, we demonstrated how  anisotropic  diffusion  tensor  and  its  coherence  features computed in an anatomically oriented breast coordinate system followed by statistical learning...

  8. Anisotropic conducting films for electromagnetic radiation applications

    Science.gov (United States)

    Cavallo, Francesca; Lagally, Max G.; Rojas-Delgado, Richard

    2015-06-16

    Electronic devices for the generation of electromagnetic radiation are provided. Also provided are methods for using the devices to generate electromagnetic radiation. The radiation sources include an anisotropic electrically conducting thin film that is characterized by a periodically varying charge carrier mobility in the plane of the film. The periodic variation in carrier mobility gives rise to a spatially varying electric field, which produces electromagnetic radiation as charged particles pass through the film.

  9. Electromagnetic field representation in inhomogeneous anisotropic media

    Science.gov (United States)

    Mohsen, A.

    1973-01-01

    Some of the basic developments in the theory of electromagnetic field representation in terms of Hertz vectors are reviewed. A solution for the field in an inhomogeneous anisotropic medium is given in terms of the two Hertz vectors. Conditions for presentation of the field in terms of uncoupled transverse electric and transverse magnetic modes, in a general orthogonal coordinate system, are derived when the permeability and permittivity tensors have only diagonal components. These conditions are compared with some known special cases.

  10. Acoustic anisotropic wavefields through perturbation theory

    KAUST Repository

    Alkhalifah, Tariq Ali

    2013-09-01

    Solving the anisotropic acoustic wave equation numerically using finite-difference methods introduces many problems and media restriction requirements, and it rarely contributes to the ability to resolve the anisotropy parameters. Among these restrictions are the inability to handle media with η<0 and the presence of shear-wave artifacts in the solution. Both limitations do not exist in the solution of the elliptical anisotropic acoustic wave equation. Using perturbation theory in developing the solution of the anisotropic acoustic wave equation allows direct access to the desired limitation-free solutions, that is, solutions perturbed from the elliptical anisotropic background medium. It also provides a platform for parameter estimation because of the ability to isolate the wavefield dependency on the perturbed anisotropy parameters. As a result, I derive partial differential equations that relate changes in the wavefield to perturbations in the anisotropy parameters. The solutions of the perturbation equations represented the coefficients of a Taylor-series-type expansion of the wavefield as a function of the perturbed parameter, which is in this case η or the tilt of the symmetry axis. The expansion with respect to the symmetry axis allows use of an acoustic transversely isotropic media with a vertical symmetry axis (VTI) kernel to estimate the background wavefield and the corresponding perturbation coefficients. The VTI extrapolation kernel is about one-fourth the cost of the transversely isotropic model with a tilt in the symmetry axis kernel. Thus, for a small symmetry axis tilt, the cost of migration using a first-order expansion can be reduced. The effectiveness of the approach was demonstrated on the Marmousi model.

  11. Anisotropic cosmological solutions in massive vector theories

    International Nuclear Information System (INIS)

    Heisenberg, Lavinia; Kase, Ryotaro; Tsujikawa, Shinji

    2016-01-01

    In beyond-generalized Proca theories including the extension to theories higher than second order, we study the role of a spatial component v of a massive vector field on the anisotropic cosmological background. We show that, as in the case of the isotropic cosmological background, there is no additional ghostly degrees of freedom associated with the Ostrogradski instability. In second-order generalized Proca theories we find the existence of anisotropic solutions on which the ratio between the anisotropic expansion rate Σ and the isotropic expansion rate H remains nearly constant in the radiation-dominated epoch. In the regime where Σ/ H is constant, the spatial vector component v works as a dark radiation with the equation of state close to 1/3. During the matter era, the ratio Σ/ H decreases with the decrease of v . As long as the conditions |Σ| || H and v 2 || φ 2 are satisfied around the onset of late-time cosmic acceleration, where φ is the temporal vector component, we find that the solutions approach the isotropic de Sitter fixed point (Σ = 0 = v ) in accordance with the cosmic no-hair conjecture. In the presence of v and Σ the early evolution of the dark energy equation of state w DE in the radiation era is different from that in the isotropic case, but the approach to the isotropic value w DE (iso) typically occurs at redshifts z much larger than 1. Thus, apart from the existence of dark radiation, the anisotropic cosmological dynamics at low redshifts is similar to that in isotropic generalized Proca theories. In beyond-generalized Proca theories the only consistent solution to avoid the divergence of a determinant of the dynamical system corresponds to v = 0, so Σ always decreases in time.

  12. Bryan's effect and anisotropic nonlinear damping

    Science.gov (United States)

    Joubert, Stephan V.; Shatalov, Michael Y.; Fay, Temple H.; Manzhirov, Alexander V.

    2018-03-01

    In 1890, G. H. Bryan discovered the following: "The vibration pattern of a revolving cylinder or bell revolves at a rate proportional to the inertial rotation rate of the cylinder or bell." We call this phenomenon Bryan's law or Bryan's effect. It is well known that any imperfections in a vibratory gyroscope (VG) affect Bryan's law and this affects the accuracy of the VG. Consequently, in this paper, we assume that all such imperfections are either minimised or eliminated by some known control method and that only damping is present within the VG. If the damping is isotropic (linear or nonlinear), then it has been recently demonstrated in this journal, using symbolic analysis, that Bryan's law remains invariant. However, it is known that linear anisotropic damping does affect Bryan's law. In this paper, we generalise Rayleigh's dissipation function so that anisotropic nonlinear damping may be introduced into the equations of motion. Using a mixture of numeric and symbolic analysis on the ODEs of motion of the VG, for anisotropic light nonlinear damping, we demonstrate (up to an approximate average), that Bryan's law is affected by any form of such damping, causing pattern drift, compromising the accuracy of the VG.

  13. ARTc: Anisotropic reflectivity and transmissivity calculator

    Science.gov (United States)

    Malehmir, Reza; Schmitt, Douglas R.

    2016-08-01

    While seismic anisotropy is known to exist within the Earth's crust and even deeper, isotropic or even highly symmetric elastic anisotropic assumptions for seismic imaging is an over-simplification which may create artifacts in the image, target mis-positioning and hence flawed interpretation. In this paper, we have developed the ARTc algorithm to solve reflectivity, transmissivity as well as velocity and particle polarization in the most general case of elastic anisotropy. This algorithm is able to provide reflectivity solution from the boundary between two anisotropic slabs with arbitrary symmetry and orientation up to triclinic. To achieve this, the algorithm solves full elastic wave equation to find polarization, slowness and amplitude of all six wave-modes generated from the incident plane-wave and welded interface. In the first step to calculate the reflectivity, the algorithm solves properties of the incident wave such as particle polarization and slowness. After calculation of the direction of generated waves, the algorithm solves their respective slowness and particle polarization. With this information, the algorithm then solves a system of equations incorporating the imposed boundary conditions to arrive at the scattered wave amplitudes, and thus reflectivity and transmissivity. Reflectivity results as well as slowness and polarization are then tested in complex computational anisotropic models to ensure their accuracy and reliability. ARTc is coded in MATLAB ® and bundled with an interactive GUI and bash script to run on single or multi-processor computers.

  14. ANALYSIS OF DEFORMABILITY OF ANISOTROPIC AGRILLITE CLAYSTONES

    Directory of Open Access Journals (Sweden)

    Ponomaryov Andrey Budimirovicn

    2017-08-01

    Full Text Available In the paper, the results of deformability study of agrillite claystones are used for determination of the Jointed rock model parameters. The number of stamp, pressuremeter and compressive tests allowed to research anisotropic deformability of argillite claystone in vertical and horizontal direction. The following problems were solved during the study: 1 the in-place and laboratory experiments to calculate the anisotropy coefficient were done for anisotropic agrillite claystones with both natural moisture and total water saturation; 2 the deformation parameters were determined and the numerical simulation of the stress-strain state of claystone in field tests was carried out with the use of Plaxis 2D software application; 3 the comparative analysis was done for calculated claystone deformation and the values obtained during the in-place tests. The authors proved that agrillite claystones shows two times less deformation under loading in the horizontal direction than vertically. The ratio is obtained to determine the parameters for numerical simulation of the Jointed Rock model used as a practical tool for analysis of stress-strain behavior of anisotropic soils. The authors provided a recommended practice for consideration of specific properties of argillite claystones when carrying out foundation works.

  15. Longitudinal fluctuations and decorrelation of anisotropic flow

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Long-Gang [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, 60438 Frankfurt am Main (Germany); Petersen, Hannah [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, 60438 Frankfurt am Main (Germany); Institute for Theoretical Physics, Goethe University, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main (Germany); GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany); Qin, Guang-You [Key Laboratory of Quark & Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079 (China); Roy, Victor [Institute for Theoretical Physics, Goethe University, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main (Germany); Wang, Xin-Nian [Key Laboratory of Quark & Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079 (China); Nuclear Science Division MS70R0319, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2016-12-15

    We investigate the decorrelation of 2nd and 3rd order anisotropic flow for charged particles in two different pseudo rapidity (η) windows by varying the pseudo rapidity gap, in an event-by-event (3+1)D ideal hydrodynamic model, with fluctuating initial conditions from A Multi-Phase Transport (AMPT) model. We visualize the parton distribution at initial state for Pb+Pb collisions at LHC and Au+Au collisions at RHIC, and demonstrate the longitudinal fluctuations originating from the asymmetry between forward and backward going participants, the fluctuations of the string length and the fluctuations due to finite number of partons at different beam energies. The decorrelation of anisotropic flow of final hadrons with large η gaps is found to originate from the spatial decorrelation along the longitudinal direction in the AMPT initial conditions through hydrodynamic evolution. The agreement between our results and recent CMS data in most centralities suggests that the string-like mechanism of initial parton production in AMPT model captures the initial longitudinal fluctuation that is responsible for the measured decorrelation of anisotropic flow in Pb+Pb collisions at LHC. Our predictions for Au+Au collisions at the highest RHIC energy show stronger longitudinal decorrelation than at LHC, indicating larger longitudinal fluctuations at lower beam energies.

  16. Magnetic fields in mixed neutron-star-plus-wormhole systems

    International Nuclear Information System (INIS)

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

    2015-01-01

    We consider mixed configurations consisting of a wormhole filled by a strongly magnetized isotropic or anisotropic neutron fluid. The nontrivial topology of the spacetime is allowed by the presence of exotic matter. By comparing these configurations with ordinary magnetized neutron stars, we clarify the question of how the presence of the nontrivial topology influences the magnetic field distribution inside the fluid. In the case of an anisotropic fluid, we find new solutions describing configurations, where the maximum of the fluid density is shifted from the center. A linear stability analysis shows that these mixed configurations are unstable

  17. Magnetic fields in mixed neutron-star-plus-wormhole systems

    Energy Technology Data Exchange (ETDEWEB)

    Aringazin, Ascar [Institute for Basic Research, Eurasian National University, 5, Munaitpasov Street, Astana, 010008 (Kazakhstan); Dzhunushaliev, Vladimir; Folomeev, Vladimir; Kleihaus, Burkhard; Kunz, Jutta, E-mail: aringazin@gmail.com, E-mail: v.dzhunushaliev@gmail.com, E-mail: vfolomeev@mail.ru, E-mail: b.kleihaus@uni-oldenburg.de, E-mail: jutta.kunz@uni-oldenburg.de [Institut für Physik, Universität Oldenburg, 114-118, Ammerländer Heerstraße, D-26111 Oldenburg (Germany)

    2015-04-01

    We consider mixed configurations consisting of a wormhole filled by a strongly magnetized isotropic or anisotropic neutron fluid. The nontrivial topology of the spacetime is allowed by the presence of exotic matter. By comparing these configurations with ordinary magnetized neutron stars, we clarify the question of how the presence of the nontrivial topology influences the magnetic field distribution inside the fluid. In the case of an anisotropic fluid, we find new solutions describing configurations, where the maximum of the fluid density is shifted from the center. A linear stability analysis shows that these mixed configurations are unstable.

  18. Understanding conoscopic interference patterns in anisotropic crystals

    Science.gov (United States)

    Olorunsola, Oluwatobi Gabriel

    The interference patterns observed in conoscopy are important in studying the optical and geometrical properties of anisotropic materials. They have also been used to identify minerals and to explore the structure of biological tissues. In a conoscopic interferometer, an optically anisotropic specimen is placed between two crossed linear polarizers and illuminated by a convergent light beam. The interference patterns are produced because in an anisotropic material an incident light is split into two eigenwaves, namely the ordinary and the extraordinary waves. We report our work on the theoretical simulation and experimental observation of the conoscopic interference patterns in anisotropic crystals. In our simulation, the interference patterns are decomposed into fringes of isogyres and isochromates. For each light propagation direction inside the crystal there exist two eigenwaves that have their own characteristic velocities and vibration directions. The isogyres are obtained by computing the angle between the polarization of the incident light and the vibration directions of the two eigenwaves. The isochromates are obtained by computing the phase retardance between the two eigenwaves inside the crystal. The interference patterns are experimentally observed in several crystals, with their optic axes either parallel or perpendicular to their surfaces. An external electric field is applied to deform the crystals from uniaxial to biaxial. The results of our experimental observation agree well with our computer simulation. In conventional interferometers the isochromatic interference fringes are observed by using a circular polarizer and a circular analyzer, both constructed by a linear polarizer and a quarter wave plate. However, due to the dispersion of the quarter wave plates, the phase-retardance between the two light waves inside the quarter wave plates is wavelength-dependent, which results in different conoscopic interference patterns for different colors of

  19. Mixed and Mixing Systems Worldwide

    African Journals Online (AJOL)

    Sean.Donlan

    MIXED AND MIXING SYSTEMS WORLDWIDE: A PREFACE. 2012 VOLUME 15 No 3 ... dissenters, Mixed Jurisdictions Worldwide galvanised scholarship on mixed systems, especially for jurists in those ... Comparative Law, the International Association of Legal Science and numerous law faculties across the classical ...

  20. Anisotropic resonant scattering from polymer photonic crystals.

    Science.gov (United States)

    Haines, Andrew I; Finlayson, Chris E; Snoswell, David R E; Spahn, Peter; Hellmann, G Peter; Baumberg, Jeremy J

    2012-11-20

    Hyperspectral goniometry reveals anisotropic scattering which dominates the visual appearance of self-assembled polymer opals. The technique allows reconstruction of the reciprocal-space of nanostructures, and indicates that chain defects formed during shear-ordering are responsible for the anisotropy in these samples. Enhanced scattering with improving order is shown to arise from increased effective refractive index contrast, while broadband background scatter is suppressed by absorptive dopants. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. An approach to anisotropic cosmologies. 6

    International Nuclear Information System (INIS)

    Raychaudhuri, A.K.

    1989-01-01

    In this paper the motivation for the study of anisotropic cosmological models is set out. Then the mathematical basis for the study of such models as well as the description of some of the exact solutions of this genre are given. Killing vectors that spell out spacetime symmetries, are defined and the Bianchi classification of spacetimes based on the structure of the Killing vectors described. After a consideration of the kinematics of matter flow some of the known solutions are presented and their properties described. (author)

  2. Anisotropic Density Estimation in Global Illumination

    DEFF Research Database (Denmark)

    Schjøth, Lars

    2009-01-01

    and bias in estimates. Good results are obtained by the use of anisotropic filtering. Two methods handles the most common cases; filtering illumination reflected from object surfaces. One methods extends filtering to the temporal domain and one performs filtering on illumination from participating media......Density estimation employed in multi-pass global illumination algorithms gives cause to a trade-off problem between bias and noise. The problem is seen most evident as blurring of strong illumination features. This thesis addresses the problem, presenting four methods that reduce both noise...

  3. Creating an anisotropic plasma resistivity with waves

    International Nuclear Information System (INIS)

    Fisch, N.J.; Boozer, A.H.

    1980-05-01

    An anisotropic plasma resistivity may be created by preferential heating of electrons traveling in one direction. This can result in a steady-state toroidal current in a tokamak even in the absence of net wave momentum. In fact, at high wave phase velocities, the current associated with the change in resistivity is greater than that associated with net momentum input. An immediate implication is that other waves, such as electron cyclotron waves, may be competitive with lower-hybrid waves as a means for generating current. An analytical expression is derived for the current generated per power dissipated which agrees remarkably well with numerical calculations

  4. Generalised model for anisotropic compact stars

    Energy Technology Data Exchange (ETDEWEB)

    Maurya, S.K. [University of Nizwa, Department of Mathematical and Physical Sciences College of Arts and Science, Nizwa (Oman); Gupta, Y.K. [Raj Kumar Goel Institute of Technology, Department of Mathematics, Ghaziabad, Uttar Pradesh (India); Ray, Saibal [Government College of Engineering and Ceramic Technology, Department of Physics, Kolkata, West Bengal (India); Deb, Debabrata [Indian Institute of Engineering Science and Technology, Shibpur, Department of Physics, Howrah, West Bengal (India)

    2016-12-15

    In the present investigation an exact generalised model for anisotropic compact stars of embedding class 1 is sought with a general relativistic background. The generic solutions are verified by exploring different physical aspects, viz. energy conditions, mass-radius relation, stability of the models, in connection to their validity. It is observed that the model presented here for compact stars is compatible with all these physical tests and thus physically acceptable as far as the compact star candidates RXJ 1856-37, SAX J 1808.4-3658 (SS1) and SAX J 1808.4-3658 (SS2) are concerned. (orig.)

  5. Effective Medium Theory for Anisotropic Metamaterials

    KAUST Repository

    Zhang, Xiujuan

    2017-11-12

    This dissertation includes the study of effective medium theories (EMTs) and their applications in describing wave propagation in anisotropic metamaterials, which can guide the design of metamaterials. An EMT based on field averaging is proposed to describe a peculiar anisotropic dispersion relation that is linear along the symmetry line but quadratic in the perpendicular direction. This dispersion relation is associated with the topological transition of the iso-frequency contours (IFCs), suggesting interesting wave propagation behaviors from beam shaping to beam splitting. In the framework of coherent potential approximation, an analytical EMT is further developed, with the ability to build a direct connection between the microscopic structure and the macroscopic material properties, which overcomes the requirement of prior knowledge of the field distributions. The derived EMT is valid beyond the long-wavelength limit. Using the EMT, an anisotropic zero-index metamaterial is designed. Moreover, the derived EMT imposes a condition that no scattered wave is generated in the ambient medium, which suggests the input signal cannot detect any object that might exist, making it invisible. Such correspondence between the EMT and the invisibilityinspires us to explore the wave cloaking in the same framework of coherent potential approximation. To further broaden the application realm of EMT, an EMT using the parameter retrieval method is studied in the regimes where the previously-developed EMTs are no longer accurate. Based on this study, in conjunction with the EMT mentioned above, a general scheme to realize coherent perfect absorption (CPA) in anisotropic metamaterials is proposed. As an exciting area in metamaterials, the field of metasurfaces has drawn great attention recently. As an easily attainable device, a grating may be the simplest version of metasurfaces. Here, an analytical EMT for gratings made of cylinders is developed by using the multiple scattering

  6. RELATIVISTIC CYCLOTRON INSTABILITY IN ANISOTROPIC PLASMAS

    Energy Technology Data Exchange (ETDEWEB)

    López, Rodrigo A.; Moya, Pablo S.; Muñoz, Víctor; Valdivia, J. Alejandro [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Navarro, Roberto E.; Araneda, Jaime A. [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Viñas, Adolfo F., E-mail: rlopez186@gmail.com [NASA Goddard Space Flight Center, Heliophysics Science Division, Geospace Physics Laboratory, Mail Code 673, Greenbelt, MD 20771 (United States)

    2016-11-20

    A sufficiently large temperature anisotropy can sometimes drive various types of electromagnetic plasma micro-instabilities, which can play an important role in the dynamics of relativistic pair plasmas in space, astrophysics, and laboratory environments. Here, we provide a detailed description of the cyclotron instability of parallel propagating electromagnetic waves in relativistic pair plasmas on the basis of a relativistic anisotropic distribution function. Using plasma kinetic theory and particle-in-cell simulations, we study the influence of the relativistic temperature and the temperature anisotropy on the collective and noncollective modes of these plasmas. Growth rates and dispersion curves from the linear theory show a good agreement with simulations results.

  7. Analysis of anisotropic shells containing flowing fluid

    International Nuclear Information System (INIS)

    Lakis, A.A.

    1983-01-01

    A general theory for the dynamic analysis of anisotropic thin cylindrical shells containing flowing fluid is presented. The shell may be uniform or non-uniform, provided it is geometrically axially symmetric. This is a finite- element theory, using cylindrical finite elements, but the displacement functions are determined by using classical shell theory. A new solution of the wave equation of the liquid finite element leads to an expression of the fluid pressure, p, as a function of the nodal displacements of the element and three operative forces (inertia, centrifugal and Coriolis) of the moving fluid. (Author) [pt

  8. On the Schrodinger equations with isotropic and anisotropic fourth-order dispersion

    Directory of Open Access Journals (Sweden)

    Elder J. Villamizar-Roa

    2016-01-01

    Full Text Available This article concerns the Cauchy problem associated with the nonlinear fourth-order Schrodinger equation with isotropic and anisotropic mixed dispersion. This model is given by the equation $$ i\\partial_tu+\\epsilon \\Delta u+\\delta A u+\\lambda|u|^\\alpha u=0,\\quad x\\in\\mathbb{R}^{n},\\; t\\in \\mathbb{R}, $$ where A is either the operator $\\Delta^2$ (isotropic dispersion or $\\sum_{i=1}^d\\partial_{x_ix_ix_ix_i}$, $1\\leq danisotropic dispersion, and $\\alpha, \\epsilon, \\lambda$ are real parameters. We obtain local and global well-posedness results in spaces of initial data with low regularity, based on weak-$L^p$ spaces. Our analysis also includes the biharmonic and anisotropic biharmonic equation $(\\epsilon=0$; in this case, we obtain the existence of self-similar solutions because of their scaling invariance property. In a second part, we analyze the convergence of solutions for the nonlinear fourth-order Schrodinger equation $$ i\\partial_tu+\\epsilon \\Delta u+\\delta \\Delta^2 u+\\lambda|u|^\\alpha u=0, \\quad x\\in\\mathbb{R}^{n},\\; t\\in \\mathbb{R}, $$ as $\\epsilon$ approaches zero, in the $H^2$-norm, to the solutions of the corresponding biharmonic equation $i\\partial_tu+\\delta \\Delta^2 u+\\lambda|u|^\\alpha u=0$.

  9. Anisotropic Self-Assembly of Organic–Inorganic Hybrid Microtoroids

    KAUST Repository

    Al-Rehili, Safa’a

    2016-10-24

    Toroidal structures based on self-assembly of predesigned building blocks are well-established in the literature, but spontaneous self-organization to prepare such structures has not been reported to date. Here, organic–inorganic hybrid microtoroids synthesized by simultaneous coordination-driven assembly of amphiphilic molecules and hydrophilic polymers are reported. Mixing amphiphilic molecules with iron(III) chloride and hydrophilic polymers in water leads, within minutes, to the formation of starlike nanostructures. A spontaneous self-organization of these nanostructures is then triggered to form stable hybrid microtoroids. Interestingly, the toroids exhibit anisotropic hierarchical growth, giving rise to a layered toroidal framework. These microstructures are mechanically robust and can act as templates to host metallic nanoparticles such as gold and silver. Understanding the nature of spontaneous assembly driven by coordination multiple non-covalent interactions can help explain the well-ordered complexity of many biological organisms in addition to expanding the available tools to mimic such structures at a molecular level.

  10. Insertion of anisotropic particles in lamellar surfactant phases

    International Nuclear Information System (INIS)

    Grillo, Isabelle

    1998-01-01

    We search for the interactions governing the possibility to mix organic and inorganic colloids. We use laponite, a synthetic anionic clay, made of 30 nm diameter and 1 nm thickness anisotropic disks. Three surfactant Systems, an anionic one (AOT), a cationic one (DDAB) and a nonionic one (C 12 E 5 ) investigate three different cases of interaction forces. We establish experimentally the equilibrium phase diagrams and characterise the structure of these ternary Systems by SANS and SAXS experiments. We quantify the adsorption. An AOT bilayer surround the particle edges; an almost complete bilayer of DDAB and C 12 E 5 is formed on the basal faces. SANS contrast variation experiments under controlled conditions along the adsorption isotherm of C 12 E 5 allow to determine the average thickness of the adsorbed surfactant layer. In the monophasic lamellar domain, the particles stay between the membranes, when the spacing is larger than the particle thickness. In the biphasic domain, dense clay aggregates are in equilibrium with a lamellar phase, containing few amount of particles. They enter in the AOT bilayers when the space between the bilayers are smaller than 8 A. From the phase diagram and interaction forces study, three conditions of stability emerge: - an osmotic one: the osmotic lamellar pressure is higher or equal to the colloidal one. - an energetic one: the interaction energy between a particle and the surfactant bilayer is close to the particle energy in aqueous suspension. - an entropic one: particles should not inhibit the stabilising fluctuations of the lamellar phase. (author) [fr

  11. Anisotropic elliptic PDEs for feature classification.

    Science.gov (United States)

    Wang, Shengfa; Hou, Tingbo; Li, Shuai; Su, Zhixun; Qin, Hong

    2013-10-01

    The extraction and classification of multitype (point, curve, patch) features on manifolds are extremely challenging, due to the lack of rigorous definition for diverse feature forms. This paper seeks a novel solution of multitype features in a mathematically rigorous way and proposes an efficient method for feature classification on manifolds. We tackle this challenge by exploring a quasi-harmonic field (QHF) generated by elliptic PDEs, which is the stable state of heat diffusion governed by anisotropic diffusion tensor. Diffusion tensor locally encodes shape geometry and controls velocity and direction of the diffusion process. The global QHF weaves points into smooth regions separated by ridges and has superior performance in combating noise/holes. Our method's originality is highlighted by the integration of locally defined diffusion tensor and globally defined elliptic PDEs in an anisotropic manner. At the computational front, the heat diffusion PDE becomes a linear system with Dirichlet condition at heat sources (called seeds). Our new algorithms afford automatic seed selection, enhanced by a fast update procedure in a high-dimensional space. By employing diffusion probability, our method can handle both manufactured parts and organic objects. Various experiments demonstrate the flexibility and high performance of our method.

  12. Lyotropic Liquid Crystal Phases from Anisotropic Nanomaterials.

    Science.gov (United States)

    Dierking, Ingo; Al-Zangana, Shakhawan

    2017-10-01

    Liquid crystals are an integral part of a mature display technology, also establishing themselves in other applications, such as spatial light modulators, telecommunication technology, photonics, or sensors, just to name a few of the non-display applications. In recent years, there has been an increasing trend to add various nanomaterials to liquid crystals, which is motivated by several aspects of materials development. (i) addition of nanomaterials can change and thus tune the properties of the liquid crystal; (ii) novel functionalities can be added to the liquid crystal; and (iii) the self-organization of the liquid crystalline state can be exploited to template ordered structures or to transfer order onto dispersed nanomaterials. Much of the research effort has been concentrated on thermotropic systems, which change order as a function of temperature. Here we review the other side of the medal, the formation and properties of ordered, anisotropic fluid phases, liquid crystals, by addition of shape-anisotropic nanomaterials to isotropic liquids. Several classes of materials will be discussed, inorganic and mineral liquid crystals, viruses, nanotubes and nanorods, as well as graphene oxide.

  13. The Effective Coherence Length in Anisotropic Superconductors

    International Nuclear Information System (INIS)

    Polturak, E.; Koren, G.; Nesher, O

    1999-01-01

    If electrons are transmitted from a normal conductor(N) into a superconductor(S), common wisdom has it that the electrons are converted into Cooper pairs within a coherence length from the interface. This is true in conventional superconductors with an isotropic order parameter. We have established experimentally that the situation is rather different in high Tc superconductors having an anisotropic order parameter. We used epitaxial thin film S/N bilayers having different interface orientations in order to inject carriers from S into N along different directions. The distance to which these carriers penetrate were determined through their effect on the Tc of the bilayers. We found that the effective coherence length is 20A only along the a or b directions, while in other directions we find a length of 250dr20A out of plane, and an even larger value for in-plane, off high symmetry directions. These observations can be explained using the Blonder-Tinkham-Klapwijk model adapted to anisotropic superconductivity. Several implications of our results on outstanding problems with high Tc junctions will be discussed

  14. Finite-difference schemes for anisotropic diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Es, Bram van, E-mail: es@cwi.nl [Centrum Wiskunde and Informatica, P.O. Box 94079, 1090GB Amsterdam (Netherlands); FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM (Netherlands); Koren, Barry [Eindhoven University of Technology (Netherlands); Blank, Hugo J. de [FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM (Netherlands)

    2014-09-01

    In fusion plasmas diffusion tensors are extremely anisotropic due to the high temperature and large magnetic field strength. This causes diffusion, heat conduction, and viscous momentum loss, to effectively be aligned with the magnetic field lines. This alignment leads to different values for the respective diffusive coefficients in the magnetic field direction and in the perpendicular direction, to the extent that heat diffusion coefficients can be up to 10{sup 12} times larger in the parallel direction than in the perpendicular direction. This anisotropy puts stringent requirements on the numerical methods used to approximate the MHD-equations since any misalignment of the grid may cause the perpendicular diffusion to be polluted by the numerical error in approximating the parallel diffusion. Currently the common approach is to apply magnetic field-aligned coordinates, an approach that automatically takes care of the directionality of the diffusive coefficients. This approach runs into problems at x-points and at points where there is magnetic re-connection, since this causes local non-alignment. It is therefore useful to consider numerical schemes that are tolerant to the misalignment of the grid with the magnetic field lines, both to improve existing methods and to help open the possibility of applying regular non-aligned grids. To investigate this, in this paper several discretization schemes are developed and applied to the anisotropic heat diffusion equation on a non-aligned grid.

  15. Lyotropic Liquid Crystal Phases from Anisotropic Nanomaterials

    Directory of Open Access Journals (Sweden)

    Ingo Dierking

    2017-10-01

    Full Text Available Liquid crystals are an integral part of a mature display technology, also establishing themselves in other applications, such as spatial light modulators, telecommunication technology, photonics, or sensors, just to name a few of the non-display applications. In recent years, there has been an increasing trend to add various nanomaterials to liquid crystals, which is motivated by several aspects of materials development. (i addition of nanomaterials can change and thus tune the properties of the liquid crystal; (ii novel functionalities can be added to the liquid crystal; and (iii the self-organization of the liquid crystalline state can be exploited to template ordered structures or to transfer order onto dispersed nanomaterials. Much of the research effort has been concentrated on thermotropic systems, which change order as a function of temperature. Here we review the other side of the medal, the formation and properties of ordered, anisotropic fluid phases, liquid crystals, by addition of shape-anisotropic nanomaterials to isotropic liquids. Several classes of materials will be discussed, inorganic and mineral liquid crystals, viruses, nanotubes and nanorods, as well as graphene oxide.

  16. Quantum electrodynamics of inhomogeneous anisotropic media

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Adrian E.R.; Lombardo, Fernando C. [Ciudad Universitaria, Departamento de Fisica Juan Jose Giambiagi, Buenos Aires (Argentina); IFIBA CONICET-UBA, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina)

    2015-02-01

    In this work we calculate the closed time path generating functional for the electromagnetic (EM) field interacting with inhomogeneous anisotropic matter. For this purpose, we first find a general expression for the electromagnetic field's influence action from the interaction of the field with a composite environment consisting in the quantum polarization degrees of freedom in each point of space, at arbitrary temperatures, connected to thermal baths. Then we evaluate the generating functional for the gauge field, in the temporal gauge, by implementing the Faddeev-Popov procedure. Finally, through the point-splitting technique, we calculate closed expressions for the energy, the Poynting vector, and the Maxwell tensor in terms of the Hadamard propagator. We show that all the quantities have contributions from the field's initial conditions and also from the matter degrees of freedom. Throughout the whole work we discuss how the gauge invariance must be treated in the formalism when the EM-field is interacting with inhomogeneous anisotropic matter. We study the electrodynamics in the temporal gauge, obtaining the EM-field's equation and a residual condition. Finally we analyze the case of the EM-field in bulk material and also discuss several general implications of our results in relation with the Casimir physics in a non-equilibrium scenario. (orig.)

  17. Lyotropic Liquid Crystal Phases from Anisotropic Nanomaterials

    Science.gov (United States)

    Dierking, Ingo

    2017-01-01

    Liquid crystals are an integral part of a mature display technology, also establishing themselves in other applications, such as spatial light modulators, telecommunication technology, photonics, or sensors, just to name a few of the non-display applications. In recent years, there has been an increasing trend to add various nanomaterials to liquid crystals, which is motivated by several aspects of materials development. (i) addition of nanomaterials can change and thus tune the properties of the liquid crystal; (ii) novel functionalities can be added to the liquid crystal; and (iii) the self-organization of the liquid crystalline state can be exploited to template ordered structures or to transfer order onto dispersed nanomaterials. Much of the research effort has been concentrated on thermotropic systems, which change order as a function of temperature. Here we review the other side of the medal, the formation and properties of ordered, anisotropic fluid phases, liquid crystals, by addition of shape-anisotropic nanomaterials to isotropic liquids. Several classes of materials will be discussed, inorganic and mineral liquid crystals, viruses, nanotubes and nanorods, as well as graphene oxide. PMID:28974025

  18. Elastic Modes of an Anisotropic Ridge Waveguide

    Directory of Open Access Journals (Sweden)

    Ameya Galinde

    2012-01-01

    Full Text Available A semi-analytical method for finding the elastic modes propagating along the edge of an anisotropic semi-infinite plate is presented. Solutions are constructed as linear combinations of a finite number of the corresponding infinite plate modes with the constraint that they decay in the direction perpendicular to the edge and collectively satisfy the free boundary condition over the edge surface. Such modes that are confined to the edge can be used to approximate solutions of acoustic ridge waveguides whose supporting structures are sufficiently far away from the free edge. The semi-infinite plate or ridge is allowed to be oriented arbitrarily in the anisotropic crystal. Modifications to the theory to find symmetric and antisymmetric solutions for special crystal orientations are also presented. Accuracy of the solutions can be improved by including more plate modes in the series. Numerical techniques to find modal dispersion relations and orientation dependent modal behavior, are discussed. Results for ridges etched in single crystal Silicon are found to be in good agreement with Finite Element simulations. It is found that variations in modal phase velocity with respect to crystal orientation are not significant, suggesting that anisotropy may not be a critical issue while designing ridge waveguides in Silicon.

  19. Electrically Anisotropic Layered Perovskite Single Crystal

    KAUST Repository

    Li, Ting-You

    2016-04-01

    Organic-inorganic hybrid perovskites (OIHPs), which are promising materials for electronic and optoelectronic applications (1-10), have made into layered organic-inorganic hybrid perovskites (LOIHPs). These LOIHPs have been applied to thin-film transistors, solar cells and tunable wavelength phosphors (11-18). It is known that devices fabricated with single crystal exhibit the superior performance, which makes the growth of large-sized single crystals critical for future device applications (19-23). However, the difficulty in growing large-sized LOIHPs single crystal with superior electrical properties limits their practical applications. Here, we report a method to grow the centimeter-scaled LOIHP single crystal of [(HOC2H4NH3)2PbI4], demonstrating the potentials in mass production. After that, we reveal anisotropic electrical and optoelectronic properties which proved the carrier propagating along inorganic framework. The carrier mobility of in-inorganic-plane (in-plane) devices shows the average value of 45 cm2 V–1 s–1 which is about 100 times greater than the record of LOIHP devices (15), showing the importance of single crystal in device application. Moreover, the LOIHP single crystals show its ultra-short carrier lifetime of 42.7 ps and photoluminescence quantum efficiency (PLQE) of 25.4 %. We expect this report to be a start of LOIHPs for advanced applications in which the anisotropic properties are needed (24-25), and meets the demand of high-speed applications and fast-response applications.

  20. Anisotropic dark energy and CMB anomalies

    International Nuclear Information System (INIS)

    Battye, Richard; Moss, Adam

    2009-01-01

    We investigate the breaking of global statistical isotropy caused by a dark energy component with an energy-momentum tensor which has point symmetry, that could represent a cubic or hexagonal crystalline lattice. In such models Gaussian, adiabatic initial conditions created during inflation can lead to anisotropies in the cosmic microwave background whose spherical harmonic coefficients are correlated, contrary to the standard assumption. We develop an adaptation of the line of sight integration method that can be applied to models where the background energy-momentum tensor is isotropic, but whose linearized perturbations are anisotropic. We then show how this can be applied to the cases of cubic and hexagonal symmetry. We compute quantities which show that such models are indistinguishable from isotropic models even in the most extreme parameter choices, in stark contrast to models with anisotropic initial conditions based on inflation. The reason for this is that the dark energy based models contribute to the CMB anisotropy via the integrated Sachs-Wolfe effect, which is only relevant when the dark energy is dominant, that is, on the very largest scales. For inflationary models, however, the anisotropy is present on all scales.

  1. Relativistic model for anisotropic strange stars

    Science.gov (United States)

    Deb, Debabrata; Chowdhury, Sourav Roy; Ray, Saibal; Rahaman, Farook; Guha, B. K.

    2017-12-01

    In this article, we attempt to find a singularity free solution of Einstein's field equations for compact stellar objects, precisely strange (quark) stars, considering Schwarzschild metric as the exterior spacetime. To this end, we consider that the stellar object is spherically symmetric, static and anisotropic in nature and follows the density profile given by Mak and Harko (2002) , which satisfies all the physical conditions. To investigate different properties of the ultra-dense strange stars we have employed the MIT bag model for the quark matter. Our investigation displays an interesting feature that the anisotropy of compact stars increases with the radial coordinate and attains its maximum value at the surface which seems an inherent property for the singularity free anisotropic compact stellar objects. In this connection we also perform several tests for physical features of the proposed model and show that these are reasonably acceptable within certain range. Further, we find that the model is consistent with the energy conditions and the compact stellar structure is stable with the validity of the TOV equation and Herrera cracking concept. For the masses below the maximum mass point in mass vs radius curve the typical behavior achieved within the framework of general relativity. We have calculated the maximum mass and radius of the strange stars for the three finite values of bag constant Bg.

  2. Building an Anisotropic Meniscus with Zonal Variations

    Science.gov (United States)

    Higashioka, Michael M.; Chen, Justin A.; Hu, Jerry C.

    2014-01-01

    Toward addressing the difficult problems of knee meniscus regeneration, a self-assembling process has been used to re-create the native morphology and matrix properties. A significant problem in such attempts is the recapitulation of the distinct zones of the meniscus, the inner, more cartilaginous and the outer, more fibrocartilaginous zones. In this study, an anisotropic and zonally variant meniscus was produced by self-assembly of the inner meniscus (100% chondrocytes) followed by cell seeding the outer meniscus (coculture of chondrocytes and meniscus cells). After 4 weeks in culture, the engineered, inner meniscus exhibited a 42% increase in both instantaneous and relaxation moduli and a 62% increase in GAG/DW, as compared to the outer meniscus. In contrast, the circumferential tensile modulus and collagen/DW of the outer zone was 101% and 129% higher, respectively, than the values measured for the inner zone. Furthermore, there was no difference in the radial tensile modulus between the control and zonal engineered menisci, suggesting that the inner and outer zones of the engineered zonal menisci successfully integrated. These data demonstrate that not only can biomechanical and biochemical properties be engineered to differ by the zone, but they can also recapitulate the anisotropic behavior of the knee meniscus. PMID:23931258

  3. Anisotropic cosmological models and generalized scalar tensor theory

    Indian Academy of Sciences (India)

    physics pp. 669–673. Anisotropic cosmological models and generalized scalar tensor theory. SUBENOY CHAKRABORTY1,*, BATUL CHANDRA SANTRA2 and ... Anisotropic cosmological models; general scalar tensor theory; inflation. PACS Nos 98.80.Hw; 04.50.+h; 98.80.Cq. 1. Introduction. Brans–Dicke theory [1] (BD ...

  4. Anisotropic static solutions in modelling highly compact bodies

    Indian Academy of Sciences (India)

    Einstein field equations for static anisotropic spheres are solved and exact interior solutions obtained. This paper extends earlier treatments to include anisotropic models which accommodate a wider variety of physically viable energy densities. Two classes of solutions are possible. The first class contains the limiting case ...

  5. Wave velocities in a pre-stressed anisotropic elastic medium

    Indian Academy of Sciences (India)

    Wave velocities in a pre-stressed anisotropic elastic medium. M D Sharma ... Modified Christoffel equations are derived for three-dimensional wave propagation in a general anisotropic medium under initial stress.The three roots of a ... Department of Mathematics, Kurukshetra University, Kurukshetra 136 119, India. UIET ...

  6. Orthonormal bases for anisotropic α-modulation spaces

    DEFF Research Database (Denmark)

    Rasmussen, Kenneth Niemann

    In this article we construct orthonormal bases for bi-variate anisotropic α-modulation spaces. The construction is based on generating a nice anisotropic α-covering and using carefully selected tensor products of univariate brushlet functions with regards to this covering. As an application, we s...

  7. Wave propagation in a general anisotropic poroelastic medium ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 116; Issue 4. Wave propagation in a general anisotropic poroelastic medium: Biot's theories and homogenisation theory. M D Sharma. Volume 116 Issue 4 August ... Keywords. Anisotropic poroelastic (APE) solid; Biot's theory; homogenisation theory; phase velocity.

  8. Modeling and Measurements of CMUTs with Square Anisotropic Plates

    DEFF Research Database (Denmark)

    la Cour, Mette Funding; Christiansen, Thomas Lehrmann; Dahl-Petersen, Christian

    2013-01-01

    The conventional method of modeling CMUTs use the isotropic plate equation to calculate the deflection, leading to deviations from FEM simulations including anisotropic effects of around 10% in center deflection. In this paper, the deflection is found for square plates using the full anisotropic ...

  9. Anisotropic Flow Measurements in ALICE at the Large Hadron Collider

    NARCIS (Netherlands)

    Bilandzic, A.

    2012-01-01

    Anisotropic flow is one of the observables which is sensitive to the properties of the created hot and dense system in heavy-ion collisions. In noncentral heavy-ion collisions the initial volume of the interacting system is anisotropic in coordinate space. Due to multiple interactions this anisotropy

  10. Existence of longitudinal waves in pre-stressed anisotropic elastic ...

    Indian Academy of Sciences (India)

    In a pre-stressed anisotropic elastic medium, three types of quasi-waves propagate along an arbi- trary direction. In general, none of the waves is truly longitudinal. The present study finds the specific directions in a pre-stressed anisotropic elastic medium along which longitudinal waves may propagate. This paper ...

  11. On the origins of the anisotropic mechanical behaviour of extruded ...

    Indian Academy of Sciences (India)

    This paper presents some experimental investigations about the origins of the anisotropic behaviour in cyclic loadings of ... In the second step, microstructural investigations were performed in order to understand the origins of the anisotropic ..... [20] Djebli A, Aid A, Bendouba M, Amrouche A, Benguediab M and Benseddiq ...

  12. Orthonormal bases for anisotropic α-modulation spaces

    DEFF Research Database (Denmark)

    Rasmussen, Kenneth Niemann

    2012-01-01

    In this article we construct orthonormal bases for bi-variate anisotropic α-modulation spaces. The construction is based on generating a nice anisotropic α-covering and using carefully selected tensor products of univariate brushlet functions with regards to this covering. As an application, we s...

  13. Critical frontier of anisotropic planar Potts ferromagnets : a new conjucture

    International Nuclear Information System (INIS)

    Tsallis, C.

    1982-01-01

    The critical frontier of the nearest-neighbour q-state Potts ferromagnet in the fully anisotropic 3-12 lattice is conjectured through a star-triangle transformation. It recovers all the available exact results concerning particular cases, namely: (i) anisotropic square lattice for all q; (ii) anisotropic triangular and honeycomb lattices for all q; (iii) anisotropic Kagome and diced lattices for q=2; (iv) isotropic 3-12 and Asanoha lattices for q=2. It provides proposals for several other planar lattices, in particular for the anisotropic Kagome (and diced) one for q different 2, where it slightly differs from the Wu 1979 conjecture (Which also satisfies the cases (i) and (iii)). The bond percolation critical probabilities on the 3-12 and Kagome lattices are determined to be respectively p sub(c) = 0.739830... and p sub(c) = 0.522372.... (Author) [pt

  14. Anisotropic phenomena in gauge/gravity duality

    International Nuclear Information System (INIS)

    Zeller, Hansjoerg

    2014-01-01

    In this thesis we use gauge/gravity duality to model anisotropic effects realised in nature. Firstly we analyse transport properties in holographic systems with a broken rotational invariance. Secondly we discuss geometries dual to IR fixed points with anisotropic scaling behaviour, which are related to quantum critical points in condensed matter systems. Gauge/gravity duality relates a gravity theory in Anti-de Sitter space to a lower dimensional strongly coupled quantum field theory in Minkowski space. Over the past decade this duality provided many insights into systems at strong coupling, e.g. quark-gluon plasma and condensed matter close to quantum critical points. One very important result computed in this framework is the value of the shear viscosity divided by the entropy density in strongly coupled theories. The quantitative result agrees very well with measurements of the ratio in quark-gluon plasma. However, for isotropic two derivative Einstein gravity it is temperature independent. We show that by breaking the rotational symmetry of a system we obtain a temperature dependent shear viscosity over entropy density. This is important to make contact with real world systems, since substances in nature display such dependence. In addition, we derive various transport properties in strongly coupled anisotropic systems using the gauge/gravity dictionary. The most notable results include an electrical conductivity with Drude behaviour in the low frequency region. This resembles conductors with broken translational invariance. However, we did not implement the breaking explicitly. Furthermore, our analysis shows that this setup models effects, resembling the piezoelectric and exoelectric effects, known from liquid crystals. In a second project we discuss a geometry with non-trivial scaling behaviour in order to model an IR fixed point of condensed matter theories. We construct the UV completion of this geometry and analyse its properties by computing the

  15. Mutations in Danish patients with long QT syndrome and the identification of a large founder family with p.F29L in KCNH2

    DEFF Research Database (Denmark)

    Christiansen, Michael; Hedley, Paula L; Theilade, Juliane

    2014-01-01

    in KCNQ1, 28 in KCNH2, 9 in SCN5A, 3 in KCNE1 and 2 in KCNE2. Twenty-six of these have only been described in the Danish population and 18 are novel. One double heterozygote (1.4% of families) was found. A founder mutation, p.F29L in KCNH2, was identified in 5 "unrelated" families. Disease association......, in 31.2% of cases, was based on the type of mutation identified (nonsense, insertion/deletion, frameshift or splice-site). Functional data was available for 22.7% of the missense mutations. None of the mutations were found in 364 Danish alleles and only three, all functionally characterised, were...

  16. Experimental evidence for anisotropic double exchange interaction driven anisotropic transport in manganite heterostructures

    NARCIS (Netherlands)

    Liao, Zhaoliang; Koster, Gertjan; Huijben, Mark; Rijnders, A.J.H.M.

    2017-01-01

    An anisotropic double exchange interaction driven giant transport anisotropy is demonstrated in a canonic double exchange system of La2/3Sr1/3MnO3 ultrathin films epitaxially grown on NdGaO3 (110) substrates. The oxygen octahedral coupling at the La2/3Sr1/3MnO3/NdGaO3 interface induces a planar

  17. Anisotropic plasmas from axion and dilaton deformations

    Energy Technology Data Exchange (ETDEWEB)

    Donos, Aristomenis [Centre for Particle Theory and Department of Mathematical Sciences, Durham University,South Rd., Durham (United Kingdom); Gauntlett, Jerome P. [Blackett Laboratory, Imperial College,Prince Consort Rd., London (United Kingdom); Sosa-Rodriguez, Omar [Centre for Particle Theory and Department of Mathematical Sciences, Durham University,South Rd., Durham (United Kingdom)

    2016-11-02

    We construct black hole solutions of type IIB supergravity that are holographically dual to anisotropic plasmas arising from deformations of an infinite class of four-dimensional CFTs. The CFTs are dual to AdS{sub 5}×X{sub 5}, where X{sub 5} is an Einstein manifold, and the deformations involve the type IIB axion and dilaton, with non-trivial periodic dependence on one of the spatial directions of the CFT. At low temperatures the solutions approach smooth domain wall solutions with the same AdS{sub 5}×X{sub 5} solution appearing in the far IR. For sufficiently large deformations an intermediate scaling regime appears which is governed by a Lifshitz-like scaling solution. We calculate the DC thermal conductivity and some components of the shear viscosity tensor.

  18. Analytical study of anisotropic compact star models

    Science.gov (United States)

    Ivanov, B. V.

    2017-11-01

    A simple classification is given of the anisotropic relativistic star models, resembling the one of charged isotropic solutions. On the ground of this database, and taking into account the conditions for physically realistic star models, a method is proposed for generating all such solutions. It is based on the energy density and the radial pressure as seeding functions. Numerous relations between the realistic conditions are found and the need for a graphic proof is reduced just to one pair of inequalities. This general formalism is illustrated with an example of a class of solutions with linear equation of state and simple energy density. It is found that the solutions depend on three free constants and concrete examples are given. Some other popular models are studied with the same method.

  19. Analytical study of anisotropic compact star models

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, B.V. [Bulgarian Academy of Science, Institute for Nuclear Research and Nuclear Energy, Sofia (Bulgaria)

    2017-11-15

    A simple classification is given of the anisotropic relativistic star models, resembling the one of charged isotropic solutions. On the ground of this database, and taking into account the conditions for physically realistic star models, a method is proposed for generating all such solutions. It is based on the energy density and the radial pressure as seeding functions. Numerous relations between the realistic conditions are found and the need for a graphic proof is reduced just to one pair of inequalities. This general formalism is illustrated with an example of a class of solutions with linear equation of state and simple energy density. It is found that the solutions depend on three free constants and concrete examples are given. Some other popular models are studied with the same method. (orig.)

  20. Fluid flow through anisotropic porous medium

    International Nuclear Information System (INIS)

    Telles, A.S.; Massarani, G.

    1975-01-01

    Darcy's equation represents a simplified form of the equation of motion for the fluid flowing through a porous medium. The simplifications concern the elimination of the acceleration, the divergence of the extra stress terms, and the assumption of existence of a linear form in the velocity for the resistive force the fluid exerts upon the solid. This hypothesis may not be valid for all anisotropic media. In some instances, measurements of directional resistivity suggest existence of the resistivity tensor, leaving entirely open the question of symmetry. In connection with this important question, an experimental scheme for the determination of the antisymmetric part of this tensor is suggested. The conclusion is that material symmetries is the only macroscopic concept that imposes restrictions on the form of the resistivity and extra stress tensors [pt

  1. Long-range interaction of anisotropic systems

    KAUST Repository

    Zhang, Junyi

    2015-02-01

    The first-order electrostatic interaction energy between two far-apart anisotropic atoms depends not only on the distance between them but also on their relative orientation, according to Rayleigh-Schrödinger perturbation theory. Using the first-order interaction energy and the continuum model, we study the long-range interaction between a pair of parallel pristine graphene sheets at zero temperature. The asymptotic form of the obtained potential density, &epsi:(D) &prop: ?D ?3 ?O(D?4), is consistent with the random phase approximation and Lifshitz theory. Accordingly, neglectance of the anisotropy, especially the nonzero first-order interaction energy, is the reason why the widely used Lennard-Jones potential approach and dispersion corrections in density functional theory give a wrong asymptotic form ε(D) &prop: ?D?4. © EPLA, 2015.

  2. Theory of Random Anisotropic Magnetic Alloys

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1976-01-01

    A mean-field-crystal-field theory is developed for random, multicomponent, anisotropic magnetic alloys. It is specially applicable to rare-earth alloys. A discussion is given of multicritical points and phase transitions between various states characterized by order parameters with different...... spatial directions or different ordering wave vectors. Theoretical predictions based on known parameters for the phase diagrams and magnetic moments for the binary rare-earth alloys of Tb, Dy, Ho, and Er, Tb-Tm, Nd-Pr, and pure double-hcp Nd agree qualitatively with the experimental observations....... Quantitative agreement can be obtained by increasing the interaction between different alloy elements, in particular for alloys with very different axial anisotropy, e.g., Tb-Tm. A model system consisting of a singlet-singlet and singlet-doublet alloy is discussed in detail. A simple procedure to include...

  3. Patterning of Structurally Anisotropic Composite Hydrogel Sheets.

    Science.gov (United States)

    Prince, Elisabeth; Alizadehgiashi, Moien; Campbell, Melissa; Khuu, Nancy; Albulescu, Alexandra; De France, Kevin; Ratkov, Dimitrije; Li, Yunfeng; Hoare, Todd; Kumacheva, Eugenia

    2018-04-09

    Compositional and structural patterns play a crucial role in the function of many biological tissues. In the present work, for nanofibrillar hydrogels formed by chemically cross-linked cellulose nanocrystals (CNC) and gelatin, we report a microextrusion-based 3D printing method to generate structurally anisotropic hydrogel sheets with CNCs aligned in the direction of extrusion. We prepared hydrogels with a uniform composition, as well as hydrogels with two different types of compositional gradients. In the first type of gradient hydrogel, the composition of the sheet varied parallel to the direction of CNC alignment. In the second hydrogel type, the composition of the sheet changed orthogonally to the direction of CNC alignment. The hydrogels exhibited gradients in structure, mechanical properties, and permeability, all governed by the compositional patterns, as well as cytocompatibility. These hydrogels have promising applications for both fundamental research and for tissue engineering and regenerative medicine.

  4. Silicon as an anisotropic mechanical material

    DEFF Research Database (Denmark)

    Thomsen, Erik Vilain; Reck, Kasper; Skands, Gustav Erik

    2014-01-01

    While silicon is an anisotropic material it is often in literature treated as an isotropic material when it comes to plate calculations. This leads to considerable errors in the calculated deflection. To overcome this problem, we present an in-depth analysis of the bending behavior of thin...... both exact analytical expressions and approximate expressions calculated by the Galerkin method. The results are applied to plates made on silicon (0 0 1), (0 1 1) and (1 1 1) substrates, respectively, and analytical equations for the deflection, strain energy and resonance frequency of such plates...... analytical models involving crystalline plates, such as those often found in the field of micro electro mechanical systems. The effect of elastic boundary conditions is taken into account by using an effective radius of the plate....

  5. Anisotropic dynamic mass density for fluidsolid composites

    KAUST Repository

    Wu, Ying

    2012-10-01

    By taking the low frequency limit of multiple-scattering theory, we obtain the dynamic effective mass density of fluidsolid composites with a two-dimensional rectangular lattice structure. The anisotropic mass density can be described by an angle-dependent dipole solution, to the leading-order of solid concentration. The angular dependence vanishes for the square lattice, but at high solid concentrations there is a structure-dependent factor that contributes to the leading-order solution. In all cases, Woods formula is found to be accurately valid for the effective bulk modulus, independent of the structures. Numerical evaluations from the solutions are shown to be in excellent agreement with finite-element simulations. © 2012 Elsevier B.V.

  6. Spectral functions from anisotropic lattice QCD

    Science.gov (United States)

    Aarts, G.; Allton, C.; Amato, A.; Evans, W.; Giudice, P.; Harris, T.; Kelly, A.; Kim, S. Y.; Lombardo, M. P.; Praki, K.; Ryan, S. M.; Skullerud, J.-I.

    2016-12-01

    The FASTSUM collaboration has been carrying out lattice simulations of QCD for temperatures ranging from one third to twice the crossover temperature, investigating the transition region, as well as the properties of the Quark Gluon Plasma. In this contribution we concentrate on quarkonium correlators and spectral functions. We work in a fixed scale scheme and use anisotropic lattices which help achieving the desirable fine resolution in the temporal direction, thus facilitating the (ill posed) integral transform from imaginary time to frequency space. We contrast and compare results for the correlators obtained with different methods, and different temporal spacings. We observe robust features of the results, confirming the sequential dissociation scenario, but also quantitative differences indicating that the methods' systematic errors are not yet under full control. We briefly outline future steps towards accurate results for the spectral functions and their associated statistical and systematic errors.

  7. Derivation of the optical constants of anisotropic

    Science.gov (United States)

    Aronson, J. R.; Emslie, A. G.; Smith, E. M.; Strong, P. F.

    1985-07-01

    This report concerns the development of methods for obtaining the optical constants of anisotropic crystals of the triclinic and monoclinic systems. The principal method used, classical dispersion theory, is adapted to these crystal systems by extending the Lorentz line parameters to include the angles characterizing the individual resonances, and by replacing the dielectric constant by a dielectric tensor. The sample crystals are gypsium, orthoclase and chalcanthite. The derived optical constants are shown to be suitable for modeling the optical properties of particulate media in the infrared spectral region. For those materials where suitable size single crystals are not available, an extension of a previously used method is applied to alabaster, a polycrystalline material of the monoclinic crystal system.

  8. Anisotropic thermal expansion in flexible materials

    Science.gov (United States)

    Romao, Carl P.

    2017-10-01

    A definition of the Grüneisen parameters for anisotropic materials is derived based on the response of phonon frequencies to uniaxial stress perturbations. This Grüneisen model relates the thermal expansion in a given direction (αi i) to one element of the elastic compliance tensor, which corresponds to the Young's modulus in that direction (Yi i). The model is tested through ab initio prediction of thermal expansion in zinc, graphite, and calcite using density functional perturbation theory, indicating that it could lead to increased accuracy for structurally complex systems. The direct dependence of αi i on Yi i suggests that materials which are flexible along their principal axes but rigid in other directions will generally display both positive and negative thermal expansion.

  9. The Anisotropic Glassy Properties of Decagonal Quasicrystals

    Directory of Open Access Journals (Sweden)

    Dragoş-Victor Anghel

    2013-01-01

    Full Text Available We use an extended version of the standard tunneling model to explain the anisotropic sound absorption in decagonal quasicrystals. The glassy properties are determined by an ensemble of two level systems (TLSs, arbitrarily oriented. The TLS is characterized by a 3 × 3 symmetric tensor, [T], which couples to the strain field, [S], through a 3 × 3 × 3 × 3 tensor of coupling constants, [R]. The structure of [R] reflects the symmetry of the quasicrystal. We also analyze the probability distributions of the elements of [T] in this particular model for a better understanding of the characteristics of “isotropic” and “anisotropic” distributions of the ensemble of TLSs. We observe that the distribution of the elements is neither simple nor intuitive and therefore it is difficult to guess it a priory, using qualitative arguments based on the symmetry properties.

  10. Final fate of charged anisotropic fluid collapse

    Science.gov (United States)

    Khan, Suhail; Shah, Hassan; Ahmad, Zahid; Ramzan, Muhammad

    2017-11-01

    This paper studies the effects of charge on spherically symmetric collapse of anisotropic fluid with a positive cosmological constant. It is observed that electromagnetic field places restriction on the bounds of cosmological constant, which acts as repulsive force against the contraction of matter content and hence the rate of destruction is faster in the presence of electromagnetic field. We have also noted that the presence of charge affects the time interval between the formation of cosmological horizon (CH) and black hole horizon (BHH). When the electric field strength E(t, r) vanishes, our investigations are in full agreement with the results obtained by Ahmad and Malik [Int. J. Theor. Phys. 55, 600 (2016)].

  11. Turbulent Output-Based Anisotropic Adaptation

    Science.gov (United States)

    Park, Michael A.; Carlson, Jan-Renee

    2010-01-01

    Controlling discretization error is a remaining challenge for computational fluid dynamics simulation. Grid adaptation is applied to reduce estimated discretization error in drag or pressure integral output functions. To enable application to high O(10(exp 7)) Reynolds number turbulent flows, a hybrid approach is utilized that freezes the near-wall boundary layer grids and adapts the grid away from the no slip boundaries. The hybrid approach is not applicable to problems with under resolved initial boundary layer grids, but is a powerful technique for problems with important off-body anisotropic features. Supersonic nozzle plume, turbulent flat plate, and shock-boundary layer interaction examples are presented with comparisons to experimental measurements of pressure and velocity. Adapted grids are produced that resolve off-body features in locations that are not known a priori.

  12. Adiabatic theory for anisotropic cold molecule collisions

    Energy Technology Data Exchange (ETDEWEB)

    Pawlak, Mariusz [Schulich Faculty of Chemistry, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Toruń (Poland); Shagam, Yuval; Narevicius, Edvardas [Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100 (Israel); Moiseyev, Nimrod [Schulich Faculty of Chemistry, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Faculty of Physics, Technion–Israel Institute of Technology, Haifa 32000 (Israel)

    2015-08-21

    We developed an adiabatic theory for cold anisotropic collisions between slow atoms and cold molecules. It enables us to investigate the importance of the couplings between the projection states of the rotational motion of the atom about the molecular axis of the diatom. We tested our theory using the recent results from the Penning ionization reaction experiment {sup 4}He(1s2s {sup 3}S) + HD(1s{sup 2}) → {sup 4}He(1s{sup 2}) + HD{sup +}(1s) + e{sup −} [Lavert-Ofir et al., Nat. Chem. 6, 332 (2014)] and demonstrated that the couplings have strong effect on positions of shape resonances. The theory we derived provides cross sections which are in a very good agreement with the experimental findings.

  13. Effective stress law for anisotropic elastic deformation

    International Nuclear Information System (INIS)

    Carroll, M.M.

    1979-01-01

    An effective stress law is derived analytically to describe the effect of pore fluid pressure on the linearly elastic response of saturated porous rocks which exhibit anisotropy. For general anisotropy the difference between the effective stress and the applied stress is not hydrostatic. The effective stress law involves two constants for transversely isotropic response and three constants for orthotropic response; these constants can be expressed in terms of the moduli of the porous material and of the solid material. These expressions simplify considerably when the anisotropy is structural rather than intrinsic, i.e., in the case of an isotropic solid material with an anisotropic pore structure. In this case the effective stress law involves the solid or grain bulk modulus and two or three moduli of the porous material, for transverse isotropy and orthotropy, respectively. The law reduces, in the case of isotropic response, to that suggested by Geertsma (1957) and by Skempton (1961) and derived analytically by Nur and Byerlee

  14. A FDM anisotropic formulation for EEG simulation.

    Science.gov (United States)

    Bruno, P; Hyttinen, J; Inchingolo, P; Magrofuoco, A; Mininel, S; Vatta, F

    2006-01-01

    Accurate head modeling is required to properly simulate bioelectric phenomena in 3-D as well as to estimate the 3-D bioelectric activity starting from superficial bioelectric measurements and 3-D imaging. Aiming to build an accurate and realistic representation of the volume conductor of the head, also the anisotropy of head tissues should be taken into account. In this paper we describe a new finite-difference method (FDM) formulation which accounts for anisotropy of the various head tissues. Our proposal, being based on FDM, derives the head model directly from patient's specific clinical images. We present here the details of the numerical formulation and the method validation by comparing our numerical proposal and known analytical results using a multi-shell anisotropic head model with skull anisotropy. Furthermore, we analyzed also different numerical grid refinement and EEG source characteristics. The comparison with previously developed FDM methods shows a good performance of the proposed method.

  15. Anisotropic magnetism in field-structured composites

    International Nuclear Information System (INIS)

    Martin, James E.; Venturini, Eugene; Odinek, Judy; Anderson, Robert A.

    2000-01-01

    Magnetic field-structured composites (FSCs) are made by structuring magnetic particle suspensions in uniaxial or biaxial (e.g., rotating) magnetic fields, while polymerizing the suspending resin. A uniaxial field produces chainlike particle structures, and a biaxial field produces sheetlike particle structures. In either case, these anisotropic structures affect the measured magnetic hysteresis loops, with the magnetic remanence and susceptibility increased significantly along the axis of the structuring field, and decreased slightly orthogonal to the structuring field, relative to the unstructured particle composite. The coercivity is essentially unaffected by structuring. We present data for FSCs of magnetically soft particles, and demonstrate that the altered magnetism can be accounted for by considering the large local fields that occur in FSCs. FSCs of magnetically hard particles show unexpectedly large anisotropies in the remanence, and this is due to the local field effects in combination with the large crystalline anisotropy of this material. (c) 2000 The American Physical Society

  16. An Anisotropic Hardening Model for Springback Prediction

    International Nuclear Information System (INIS)

    Zeng, Danielle; Xia, Z. Cedric

    2005-01-01

    As more Advanced High-Strength Steels (AHSS) are heavily used for automotive body structures and closures panels, accurate springback prediction for these components becomes more challenging because of their rapid hardening characteristics and ability to sustain even higher stresses. In this paper, a modified Mroz hardening model is proposed to capture realistic Bauschinger effect at reverse loading, such as when material passes through die radii or drawbead during sheet metal forming process. This model accounts for material anisotropic yield surface and nonlinear isotropic/kinematic hardening behavior. Material tension/compression test data are used to accurately represent Bauschinger effect. The effectiveness of the model is demonstrated by comparison of numerical and experimental springback results for a DP600 straight U-channel test

  17. Recent developments in anisotropic heterogeneous shell theory

    CERN Document Server

    Grigorenko, Alexander Ya; Grigorenko, Yaroslav M; Vlaikov, Georgii G

    2016-01-01

    This volume focuses on the relevant general theory and presents some first applications, namely those based on classical shell theory. After a brief introduction, during which the history and state-of-the-art are discussed, the first chapter presents the mechanics of anisotropic heterogeneous shells, covering all relevant assumptions and the basic relations of 3D elasticity, classical and refined shell models. The second chapter examines the numerical techniques that are used, namely discrete orthogonalization, spline-collocation and Fourier series, while the third highlights applications based on classical theory, in particular, the stress-strain state of shallow shells, non-circular shells, shells of revolution, and free vibrations of conical shells. The book concludes with a summary and an outlook bridging the gap to the second volume.

  18. Predictions from an anisotropic inflationary era

    International Nuclear Information System (INIS)

    Pitrou, Cyril; Uzan, Jean-Philippe; Pereira, Thiago S

    2008-01-01

    This paper investigates the predictions of an inflationary phase starting from a homogeneous and anisotropic universe of the Bianchi I type. After discussing the evolution of the background spacetime, focusing on the number of e-folds and the isotropization, we solve the perturbation equations and predict the power spectra of the curvature perturbations and gravity waves at the end of inflation. The main features of the early anisotropic phase is (1) a dependence of the spectra on the direction of the modes, (2) a coupling between curvature perturbations and gravity waves and (3) the fact that the two gravity wave polarizations do not share the same spectrum on large scales. All these effects are significant only on large scales and die out on small scales where isotropy is recovered. They depend on a characteristic scale that can, but a priori must not, be tuned to some observable scale. To fix the initial conditions, we propose a procedure that generalizes the one standardly used in inflation but that takes into account the fact that the WKB regime is violated at early times when the shear dominates. We stress that there exist modes that do not satisfy the WKB condition during the shear-dominated regime and for which the amplitude at the end of inflation depends on unknown initial conditions. On such scales, inflation loses its predictability. This study paves the way for the determination of the cosmological signature of a primordial shear, whatever the Bianchi I spacetime. It thus stresses the importance of the WKB regime to draw inflationary predictions and demonstrates that, when the number of e-folds is large enough, the predictions converge toward those of inflation in a Friedmann–Lemaître spacetime but that they are less robust in the case of an inflationary era with a small number of e-folds

  19. Effective orthorhombic anisotropic models for wavefield extrapolation

    KAUST Repository

    Ibanez-Jacome, W.

    2014-07-18

    Wavefield extrapolation in orthorhombic anisotropic media incorporates complicated but realistic models to reproduce wave propagation phenomena in the Earth\\'s subsurface. Compared with the representations used for simpler symmetries, such as transversely isotropic or isotropic, orthorhombic models require an extended and more elaborated formulation that also involves more expensive computational processes. The acoustic assumption yields more efficient description of the orthorhombic wave equation that also provides a simplified representation for the orthorhombic dispersion relation. However, such representation is hampered by the sixth-order nature of the acoustic wave equation, as it also encompasses the contribution of shear waves. To reduce the computational cost of wavefield extrapolation in such media, we generate effective isotropic inhomogeneous models that are capable of reproducing the firstarrival kinematic aspects of the orthorhombic wavefield. First, in order to compute traveltimes in vertical orthorhombic media, we develop a stable, efficient and accurate algorithm based on the fast marching method. The derived orthorhombic acoustic dispersion relation, unlike the isotropic or transversely isotropic ones, is represented by a sixth order polynomial equation with the fastest solution corresponding to outgoing P waves in acoustic media. The effective velocity models are then computed by evaluating the traveltime gradients of the orthorhombic traveltime solution, and using them to explicitly evaluate the corresponding inhomogeneous isotropic velocity field. The inverted effective velocity fields are source dependent and produce equivalent first-arrival kinematic descriptions of wave propagation in orthorhombic media. We extrapolate wavefields in these isotropic effective velocity models using the more efficient isotropic operator, and the results compare well, especially kinematically, with those obtained from the more expensive anisotropic extrapolator.

  20. Estimating anisotropic diffusion of neutrons near the boundary of a pebble bed random system

    Energy Technology Data Exchange (ETDEWEB)

    Vasques, R. [Department of Mathematics, Center for Computational Engineering Science, RWTH Aachen University, Schinkel Strasse 2, D-52062 Aachen (Germany)

    2013-07-01

    Due to the arrangement of the pebbles in a Pebble Bed Reactor (PBR) core, if a neutron is located close to a boundary wall, its path length probability distribution function in directions of flight parallel to the wall is significantly different than in other directions. Hence, anisotropic diffusion of neutrons near the boundaries arises. We describe an analysis of neutron transport in a simplified 3-D pebble bed random system, in which we investigate the anisotropic diffusion of neutrons born near one of the system's boundary walls. While this simplified system does not model the actual physical process that takes place near the boundaries of a PBR core, the present work paves the road to a formulation that may enable more accurate diffusion simulations of such problems to be performed in the future. Monte Carlo codes have been developed for (i) deriving realizations of the 3-D random system, and (ii) performing 3-D neutron transport inside the heterogeneous model; numerical results are presented for three different choices of parameters. These numerical results are used to assess the accuracy of estimates for the mean-squared displacement of neutrons obtained with the diffusion approximations of the Atomic Mix Model and of the recently introduced [1] Non-Classical Theory with angular-dependent path length distribution. The Non-Classical Theory makes use of a Generalized Linear Boltzmann Equation in which the locations of the scattering centers in the system are correlated and the distance to collision is not exponentially distributed. We show that the results predicted using the Non-Classical Theory successfully model the anisotropic behavior of the neutrons in the random system, and more closely agree with experiment than the results predicted by the Atomic Mix Model. (authors)

  1. Tunneling anisotropic magnetoresistance driven by magnetic phase transition.

    Science.gov (United States)

    Chen, X Z; Feng, J F; Wang, Z C; Zhang, J; Zhong, X Y; Song, C; Jin, L; Zhang, B; Li, F; Jiang, M; Tan, Y Z; Zhou, X J; Shi, G Y; Zhou, X F; Han, X D; Mao, S C; Chen, Y H; Han, X F; Pan, F

    2017-09-06

    The independent control of two magnetic electrodes and spin-coherent transport in magnetic tunnel junctions are strictly required for tunneling magnetoresistance, while junctions with only one ferromagnetic electrode exhibit tunneling anisotropic magnetoresistance dependent on the anisotropic density of states with no room temperature performance so far. Here, we report an alternative approach to obtaining tunneling anisotropic magnetoresistance in α'-FeRh-based junctions driven by the magnetic phase transition of α'-FeRh and resultantly large variation of the density of states in the vicinity of MgO tunneling barrier, referred to as phase transition tunneling anisotropic magnetoresistance. The junctions with only one α'-FeRh magnetic electrode show a magnetoresistance ratio up to 20% at room temperature. Both the polarity and magnitude of the phase transition tunneling anisotropic magnetoresistance can be modulated by interfacial engineering at the α'-FeRh/MgO interface. Besides the fundamental significance, our finding might add a different dimension to magnetic random access memory and antiferromagnet spintronics.Tunneling anisotropic magnetoresistance is promising for next generation memory devices but limited by the low efficiency and functioning temperature. Here the authors achieved 20% tunneling anisotropic magnetoresistance at room temperature in magnetic tunnel junctions with one α'-FeRh magnetic electrode.

  2. Increasing Black Hole Feedback-induced Quenching with Anisotropic Thermal Conduction

    Energy Technology Data Exchange (ETDEWEB)

    Kannan, Rahul; Vogelsberger, Mark [Department of Physics, Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge 02139, MA (United States); Pfrommer, Christoph; Weinberger, Rainer; Springel, Volker; Pakmor, Rüdiger [Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany); Hernquist, Lars [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Puchwein, Ewald, E-mail: kannanr@mit.edu [Institute of Astronomy and Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge, CB3 0HA (United Kingdom)

    2017-03-10

    Feedback from central supermassive black holes is often invoked to explain the low star formation rates (SFRs) in the massive galaxies at the centers of galaxy clusters. However, the detailed physics of the coupling of the injected feedback energy with the intracluster medium (ICM) is still unclear. Using high-resolution magnetohydrodynamic cosmological simulations of galaxy cluster formation, we investigate the role of anisotropic thermal conduction in shaping the thermodynamic structure of clusters, and in particular, in modifying the impact of black hole feedback. Stratified anisotropically conducting plasmas are formally always unstable, and thus more prone to mixing, an expectation borne out by our results. The increased mixing efficiently isotropizes the injected feedback energy, which in turn significantly improves the coupling between the feedback energy and the ICM. This facilitates an earlier disruption of the cool-core, reduces the SFR by more than an order of magnitude, and results in earlier quenching despite an overall lower amount of feedback energy injected into the cluster core. With conduction, the metallicity gradients and dispersions are lowered, aligning them better with observational constraints. These results highlight the important role of thermal conduction in establishing and maintaining the quiescence of massive galaxies.

  3. Development of laser ablation plasma by anisotropic self-radiation

    Directory of Open Access Journals (Sweden)

    Ohnishi Naofumi

    2013-11-01

    Full Text Available We have proposed a method for reproducing an accurate solution of low-density ablation plasma by properly treating anisotropic radiation. Monte-Carlo method is employed for estimating Eddington tensor with limited number of photon samples in each fluid time step. Radiation field from ablation plasma is significantly affected by the anisotropic Eddington tensor. Electron temperature around the ablation surface changes with the radiation field and is responsible for the observed emission. An accurate prediction of the light emission from the laser ablation plasma requires a careful estimation of the anisotropic radiation field.

  4. Mixing Ventilation

    DEFF Research Database (Denmark)

    Kandzia, Claudia; Kosonen, Risto; Melikov, Arsen Krikor

    In this guidebook most of the known and used in practice methods for achieving mixing air distribution are discussed. Mixing ventilation has been applied to many different spaces providing fresh air and thermal comfort to the occupants. Today, a design engineer can choose from large selection...

  5. Reinterpreting aircraft measurements in anisotropic scaling turbulence

    Directory of Open Access Journals (Sweden)

    S. J. Hovde

    2009-07-01

    Full Text Available Due to both systematic and turbulent induced vertical fluctuations, the interpretation of atmospheric aircraft measurements requires a theory of turbulence. Until now virtually all the relevant theories have been isotropic or "quasi isotropic" in the sense that their exponents are the same in all directions. However almost all the available data on the vertical structure shows that it is scaling but with exponents different from the horizontal: the turbulence is scaling but anisotropic. In this paper, we show how such turbulence can lead to spurious breaks in the scaling and to the spurious appearance of the vertical scaling exponent at large horizontal lags.

    We demonstrate this using 16 legs of Gulfstream 4 aircraft near the top of the troposphere following isobars each between 500 and 3200 km in length. First we show that over wide ranges of scale, the horizontal spectra of the aircraft altitude are nearly k-5/3. In addition, we show that the altitude and pressure fluctuations along these fractal trajectories have a high degree of coherence with the measured wind (especially with its longitudinal component. There is also a strong phase relation between the altitude, pressure and wind fluctuations; for scales less than ≈40 km (on average the wind fluctuations lead the pressure and altitude, whereas for larger scales, the pressure fluctuations leads the wind. At the same transition scale, there is a break in the wind spectrum which we argue is caused by the aircraft starting to accurately follow isobars at the larger scales. In comparison, the temperature and humidity have low coherencies and phases and there are no apparent scale breaks, reinforcing the hypothesis that it is the aircraft trajectory that is causally linked to the scale breaks in the wind measurements.

    Using spectra and structure functions for the wind, we then estimate their exponents (β, H at small (5/3, 1/3 and large scales (2

  6. Hydrodynamic cavitation in Stokes flow of anisotropic fluids.

    Science.gov (United States)

    Stieger, Tillmann; Agha, Hakam; Schoen, Martin; Mazza, Marco G; Sengupta, Anupam

    2017-05-30

    Cavitation, the nucleation of vapour in liquids, is ubiquitous in fluid dynamics, and is often implicated in a myriad of industrial and biomedical applications. Although extensively studied in isotropic liquids, corresponding investigations in anisotropic liquids are largely lacking. Here, by combining liquid crystal microfluidic experiments, nonequilibrium molecular dynamics simulations and theoretical arguments, we report flow-induced cavitation in an anisotropic fluid. The cavitation domain nucleates due to sudden pressure drop upon flow past a cylindrical obstacle within a microchannel. For an anisotropic fluid, the inception and growth of the cavitation domain ensued in the Stokes regime, while no cavitation was observed in isotropic liquids flowing under similar hydrodynamic parameters. Using simulations we identify a critical value of the Reynolds number for cavitation inception that scales inversely with the order parameter of the fluid. Strikingly, the critical Reynolds number for anisotropic fluids can be 50% lower than that of isotropic fluids.

  7. Liquid Crystal Elastomer Actuators from Anisotropic Porous Polymer Template.

    Science.gov (United States)

    Wang, Qian; Yu, Li; Yu, Meina; Zhao, Dongyu; Song, Ping; Chi, Hun; Guo, Lin; Yang, Huai

    2017-08-01

    Controlling self-assembly behaviors of liquid crystals is a fundamental issue for designing them as intelligent actuators. Here, anisotropic porous polyvinylidene fluoride film is utilized as a template to induce homogeneous alignment of liquid crystals. The mechanism of liquid crystal alignment induced by anisotropic porous polyvinylidene fluoride film is illustrated based on the relationship between the alignment behavior of liquid crystals and surface microstructure of anisotropic polyvinylidene fluoride film. Liquid crystal elastomer actuators with fast responsiveness, large strain change, and reversible actuation behaviors are achieved by the photopolymerization of liquid crystal monomer in liquid crystal cells coated with anisotropic porous films. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Acoustic frequency filter based on anisotropic topological phononic crystals

    KAUST Repository

    Chen, Zeguo

    2017-11-02

    We present a design of acoustic frequency filter based on a two-dimensional anisotropic phononic crystal. The anisotropic band structure exhibits either a directional or a combined (global + directional) bandgap at certain frequency regions, depending on the geometry. When the time-reversal symmetry is broken, it may introduce a topologically nontrivial bandgap. The induced nontrivial bandgap and the original directional bandgap result in various interesting wave propagation behaviors, such as frequency filter. We develop a tight-binding model to characterize the effective Hamiltonian of the system, from which the contribution of anisotropy is explicitly shown. Different from the isotropic cases, the Zeeman-type splitting is not linear and the anisotropic bandgap makes it possible to achieve anisotropic propagation characteristics along different directions and at different frequencies.

  9. Two-dimensional static deformation of an anisotropic medium

    Indian Academy of Sciences (India)

    1989). Chou (1976) and Ting (1995) discussed antiplane strain deformation of an anisotropic medium. Garg et al (1996) obtained representations of seismic sources causing antiplane strain deformations of orthotropic media. The corresponding ...

  10. Change of energy of photons passing through rotating anisotropic elements

    CERN Document Server

    Bagini, V; Santarsiero, M; Frezza, F; Schettini, G; Schirripa-Spagnolo, G

    1994-01-01

    We discuss simple experiments where the concept of angular momentum of a photon can be put to use in order to explain the photon energy changes that are produced by the passage of light beams through rotating anisotropic elements. (author)

  11. Fabrication of anisotropic multifunctional colloidal carriers

    Science.gov (United States)

    Jerri, Huda A.

    The field of colloidal assembly has grown tremendously in recent years, although the direct or template-assisted methods used to fabricate complex colloidal constructions from monodisperse micro- and nanoparticles have been generally demonstrated on model materials. In this work, novel core particle syntheses, particle functionalizations and bottom-up assembly techniques are presented to create functional colloidal devices. Using particle lithography, high-information colloidal vectors have been developed and modified with imaging and targeting agents. Localized nanoscale patches have been reliably positioned on microparticles to serve as foundations for further chemical or physical modifications. Site-specific placement of RGD targeting ligands has been achieved in these lithographed patches. Preferential uptake of these targeted vectors by RGD-specific 3T3 fibroblasts was verified using confocal laser scanning microscopy. A transition was made from the functionalization of model imaging core particles to the lithography of colloidal cartridges, in an effort to construct colloidal syringes with specialized, programmable release profiles. A variety of functional, pH-sensitive fluorescent cores were engineered to respond to solution conditions. When triggered, the diverse composite core microparticles and reservoir microcapsules released embedded fluorescent moieties such as dye molecules, and fluorophore-conjugated nanoparticles. The microcapsules, created using layer-by-layer polyelectrolyte deposition on sacrificial templates, were selectively modified with a robust coating. The pH-responsive anisotropic reservoir microcapsules were extremely stable in solution, and exhibited a "Lazarus" functionality of rehydrating to their original state following desiccation. A snapshot of focused-release of core constituents through the lone opening in colloidal monotremes has been obtained by anisotropically-functionalizing degradable cores with barrier shells. Additionally

  12. Spin and orbital angular momentum propagation in anisotropic media: theory

    International Nuclear Information System (INIS)

    Picón, Antonio; Benseny, Albert; Mompart, Jordi; Calvo, Gabriel F

    2011-01-01

    This paper is devoted to a study of the propagation of light beams carrying orbital angular momentum in optically anisotropic media. We first review some properties of homogeneous anisotropic media, and describe how the paraxial formalism is modified in order to proceed with a new approach dealing with the general setting of paraxial propagation along uniaxial inhomogeneous media. This approach is suitable for describing space-variant optical-axis phase plates

  13. Hybrid anisotropic materials for wind power turbine blades

    CERN Document Server

    Golfman, Yosif

    2012-01-01

    Based on rapid technological developments in wind power, governments and energy corporations are aggressively investing in this natural resource. Illustrating some of the crucial new breakthroughs in structural design and application of wind energy generation machinery, Hybrid Anisotropic Materials for Wind Power Turbine Blades explores new automated, repeatable production techniques that expand the use of robotics and process controls. These practices are intended to ensure cheaper fabrication of less-defective anisotropic material composites used to manufacture power turbine blades. This boo

  14. Anisotropic wave-equation traveltime and waveform inversion

    KAUST Repository

    Feng, Shihang

    2016-09-06

    The wave-equation traveltime and waveform inversion (WTW) methodology is developed to invert for anisotropic parameters in a vertical transverse isotropic (VTI) meidum. The simultaneous inversion of anisotropic parameters v0, ε and δ is initially performed using the wave-equation traveltime inversion (WT) method. The WT tomograms are then used as starting background models for VTI full waveform inversion. Preliminary numerical tests on synthetic data demonstrate the feasibility of this method for multi-parameter inversion.

  15. Stress propagation in isotropic packs with anisotropic boundaries

    Science.gov (United States)

    Krapf, Nathan; Witten, Thomas

    2010-03-01

    Stresses in marginally jammed, anisotropic packs built up from a solid floor propagate along oblique rays toward the floor footnotetext D. A. Head, A. V. Tkachenko, and T. A. Witten. Eur. Phys. J. E 6, 99-105 (2001)). This clear anisotropic propagation must result from anisotropic packing and/or anisotropic boundary conditions. Here we numerically isolate the effect of anisotropic boundaries by using an explicitly isotropic periodic pack in a marginally jammed, isostatic state. We then remove the periodicity in one direction and anchor the beads along one edge to a substrate. This preserves the isostatic condition while rendering the boundary anisotropic. However, we find hyperstatic modes along one edge of the pack and hypostatic modes at the other. We show that these extra modes decay rapidly away from the boundaries. Remarkably the hypostatic modes cause the pack to be unstable under any force applied to a single bead. This instability can be remedied by applying a suitable cluster of forces to adjacent beads, allowing a clear measurement of the bulk response. We discuss the resulting stress response.

  16. A unified theoretical and experimental study of anisotropic hardening

    International Nuclear Information System (INIS)

    Boehler, J.P.; Raclin, J.

    1981-01-01

    The purpose of this work is to develop a consistent formulation of the constitutive relations regarding anisotropic hardening materials. Attention is focused on the appearance and the evolution of mechanical anisotropies during irreversible processes, such as plastic forming and inelastic deformation of structures. The representation theorems for anisotropic tensor functions constitute a theoretical basis, allowing to reduce arbitrariness and to obtain a unified formulation of anisotropic hardening. In this approach, a general three-dimensional constitutive law is developed for prestrained initially orthotropic materials. Introduction of the plastic behavior results in the general forms of both the flow-law and the yield criterion. The developed theory is then specialized for the case of plane stress and different modes of anisotropic hardening are analyzed. A new generalization of the Von Mises criterion is proposed, in considering a homogeneous form of order two in stress and employing the simplest combinations of the basic invariants entering the general form of the yield condition. The proposed criterion involves specific terms accounting for the initial anisotropy, the deformation induced anisotropy and correlative terms between initial and induced anisotropy. The effects of prestrainings result in both isotropic and anisotropic hardening. An adequate experimental program, consisting of uniaxial tensile tests on oriented specimens of prestrained sheet-metal, was performed, in order to determine the specific form and the evolution of the anisotropic failure criterion for soft-steel subjected to different irreversible prestrainings. (orig.)

  17. A frequency shaping neural recorder with 3 pF input capacitance and 11 plus 4.5 bits dynamic range.

    Science.gov (United States)

    Xu, Jian; Wu, Tong; Liu, Wentai; Yang, Zhi

    2014-08-01

    This paper presents a frequency-shaping (FS) neural recording architecture and its implementation in a 0.13 μ m CMOS process. Compared with its conventional counterpart, the proposed architecture inherently rejects electrode offset, increases input impedance 5-10 fold, compresses neural data dynamic range (DR) by 4.5-bit, simultaneously records local field potentials (LFPs) and extracellular spikes, and is more suitable for long-term recording experiments. Measured at a 40 kHz sampling clock and ± 0.6 V supply, the recorder consumes 50 μW/ch, of which 22 μW per FS amplifier, 24 μ W per buffer, 4 μ W per 11-bit successive approximation register analog-to-digital converter (SAR ADC). The input-referred noise for LFPs and extracellular spikes are 13 μ Vrms and 7 μVrms, respectively, which are sufficient to achieve high-fidelity full-spectrum neural data. In addition, the designed recorder has a 3 pF input capacitance and allows " 11+4.5"-bit neural data DR without system saturation, where the extra 4.5-bit owes to the FS technique. Its figure-of-merit (FOM) based on data DR reaches 36.0 fJ/conversion-step.

  18. A 2.5 mW 370 mV/pF high linearity stray-immune symmetrical readout circuit for capacitive sensors

    Science.gov (United States)

    Kaimin, Zhou; Ziqiang, Wang; Chun, Zhang; Zhihua, Wang

    2012-06-01

    A stray-insensitive symmetrical capacitance-to-voltage converter for capacitive sensors is presented. By introducing a reference branch, a symmetrical readout circuit is realized. The linear input range is increased, and the systematic offsets of two input op-amps are cancelled. The common-mode noise and even-order distortion are also rejected. A chopper stabilization technique is adopted to further reduce the offset and flicker noise of the op-amps, and a Verilog-A-based varactor is used to model the real variable sensing capacitor. Simulation results show that the output voltage of this proposed readout circuit responds correctly, while the under-test capacitance changes with a frequency of 1 kHz. A metal-insulator-metal capacitor array is designed on chip for measurement, and the measurement results show that this circuit achieves sensitivity of 370 mV/pF, linearity error below 1% and power consumption as low as 2.5 mW. This symmetrical readout circuit can respond to an FPGA controlled sensing capacitor array changed every 1 ms.

  19. Coefficient adaptive triangulation for strongly anisotropic problems

    Energy Technology Data Exchange (ETDEWEB)

    D`Azevedo, E.F.; Romine, C.H.; Donato, J.M.

    1996-01-01

    Second order elliptic partial differential equations arise in many important applications, including flow through porous media, heat conduction, the distribution of electrical or magnetic potential. The prototype is the Laplace problem, which in discrete form produces a coefficient matrix that is relatively easy to solve in a regular domain. However, the presence of anisotropy produces a matrix whose condition number is increased, making the resulting linear system more difficult to solve. In this work, we take the anisotropy into account in the discretization by mapping each anisotropic region into a ``stretched`` coordinate space in which the anisotropy is removed. The region is then uniformly triangulated, and the resulting triangulation mapped back to the original space. The effect is to generate long slender triangles that are oriented in the direction of ``preferred flow.`` Slender triangles are generally regarded as numerically undesirable since they tend to cause poor conditioning; however, our triangulation has the effect of producing effective isotropy, thus improving the condition number of the resulting coefficient matrix.

  20. Schroedinger covariance states in anisotropic waveguides

    International Nuclear Information System (INIS)

    Angelow, A.; Trifonov, D.

    1995-03-01

    In this paper Squeezed and Covariance States based on Schroedinger inequality and their connection with other nonclassical states are considered for particular case of anisotropic waveguide in LiNiO 3 . Here, the problem of photon creation and generation of squeezed and Schroedinger covariance states in optical waveguides is solved in two steps: 1. Quantization of electromagnetic field is provided in the presence of dielectric waveguide using normal-mode expansion. The photon creation and annihilation operators are introduced, expanding the solution A-vector(r-vector,t) in a series in terms of the Sturm - Liouville mode-functions. 2. In terms of these operators the Hamiltonian of the field in a nonlinear waveguide is derived. For such Hamiltonian we construct the covariance states as stable (with nonzero covariance), which minimize the Schroedinger uncertainty relation. The evolutions of the three second momenta of q-circumflex j and p-circumflex j are calculated. For this Hamiltonian all three momenta are expressed in terms of one real parameters s only. It is found out how covariance, via this parameter s, depends on the waveguide profile n(x,y), on the mode-distributions u-vector j (x,y), and on the waveguide phase mismatching Δβ. (author). 37 refs

  1. Anisotropic Charged Fluid Sphere in Isotropic Coordinates

    Directory of Open Access Journals (Sweden)

    Neeraj Pant

    2014-01-01

    Full Text Available We have presented a class of charged superdense star models, starting with a static spherically symmetric metric in isotropic coordinates for anisotropic fluid by considering Hajj-Boutros-(1986 type metric potential and a specific choice of electrical intensity E and anisotropy factor Δ which involve charge parameter K and anisotropy parameter α. The solution is well behaved for all the values of Schwarzschild compactness parameter u lying in the range 0

  2. Numerical calculation of spatially variant anisotropic metamaterials

    Science.gov (United States)

    Gulib, Asad Ullah Hil

    3D printing, or additive manufacturing, is rapidly evolving into a mainstream manufacturing technology that is creating new opportunities for electromagnetics and circuits. 3D printing permits circuits to fully utilize the third dimension allowing more functions in the same amount of space and allows the devices to have arbitrary form factors. 3D printing is letting us discover new physics that is not possible in standard 2D circuits and devices. However, evolving electromagnetics and circuits into three dimensions introduces some serious problems like thermal management, interference, and mutual coupling between the components which degrades performance and hurts signal integrity. Metamaterials are engineered composites that exhibit extreme electromagnetic properties and allow extraordinary control over electromagnetic fields. The EM Lab is developing spatially-variant anisotropic metamaterials (SVAMs) as a solution to mitigate mutual coupling between components. The concept of SVAMs is to electrically stretch the space between components to reduce mutual coupling. To do this, alternating layers of different dielectric must bisect adjacent components. However, the overall dielectric fill must also conform around dozens of electrical components and be smooth, continuous, and defect free. The research described here is the first prototype of an algorithm which generates a SVAM infill between all of the electrical components of a circuit in order to reduce the mutual coupling.

  3. P wave anisotropic tomography of the Alps

    Science.gov (United States)

    Hua, Yuanyuan; Zhao, Dapeng; Xu, Yixian

    2017-06-01

    The first tomographic images of P wave azimuthal and radial anisotropies in the crust and upper mantle beneath the Alps are determined by joint inversions of arrival time data of local earthquakes and teleseismic events. Our results show the south dipping European plate with a high-velocity (high-V) anomaly beneath the western central Alps and the north dipping Adriatic plate with a high-V anomaly beneath the Eastern Alps, indicating that the subduction polarity changes along the strike of the Alps. The P wave azimuthal anisotropy is characterized by mountain chain-parallel fast-velocity directions (FVDs) in the western central Alps and NE-SW FVDs in the Eastern Alps, which may be caused by mantle flow induced by the slab subductions. Our results reveal a negative radial anisotropy (i.e., Vph Vph > Vpv) in the low-velocity mantle wedge, which may reflect the subvertical plate subduction and its induced mantle flow. The results of anisotropic tomography provide important new information on the complex mantle structure and dynamics of the Alps and adjacent regions.

  4. Anisotropic behaviour of human gallbladder walls.

    Science.gov (United States)

    Li, W G; Hill, N A; Ogden, R W; Smythe, A; Majeed, A W; Bird, N; Luo, X Y

    2013-04-01

    Inverse estimation of biomechanical parameters of soft tissues from non-invasive measurements has clinical significance in patient-specific modelling and disease diagnosis. In this paper, we propose a fully nonlinear approach to estimate the mechanical properties of the human gallbladder wall muscles from in vivo ultrasound images. The iteration method consists of a forward approach, in which the constitutive equation is based on a modified Hozapfel-Gasser-Ogden law initially developed for arteries. Five constitutive parameters describing the two orthogonal families of fibres and the matrix material are determined by comparing the computed displacements with medical images. The optimisation process is carried out using the MATLAB toolbox, a Python code, and the ABAQUS solver. The proposed method is validated with published artery data and subsequently applied to ten human gallbladder samples. Results show that the human gallbladder wall is anisotropic during the passive refilling phase, and that the peak stress is 1.6 times greater than that calculated using linear mechanics. This discrepancy arises because the wall thickness reduces by 1.6 times during the deformation, which is not predicted by conventional linear elasticity. If the change of wall thickness is accounted for, then the linear model can used to predict the gallbladder stress and its correlation with pain. This work provides further understanding of the nonlinear characteristics of human gallbladder. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Anisotropic reflectance characteristics of natural Earth surfaces.

    Science.gov (United States)

    Brennan, B; Bandeen, W R

    1970-02-01

    The patterns of reflection of solar radiation from cloud, water, and land surfaces were measured with an aircraft-borne medium resolution radiometer. Reflectances in the 0.2-4.0-micro and 0.55-0.85-micro portions of the electromagnetic spectrum were investigated. Results indicate that the reflectance characteristics of most of the surface types measured are anisotropic. The anisotropy is dependent on the type of surface and the angles of incidence and reflection. In general, the anisotropy increases with increasing solar zenith angle. Clouds and forests show similar reflectance patterns, with forward and backward scattering peaks. Ocean surfaces yield a pattern similar to those of the clouds and forests but with an additional peak which is associated with sun glitter. Reflectances measured in the 0.2-4.0-micro band are generally lower than those in the 0.55-0.85-micro band under cloudy conditions. Anisotropy and spectral bandwidth should be accounted for when computing the albedo of the earth from narrow field-of-view measurements from satellites; otherwise, large errors may be expected to occur.

  6. Application of the anisotropic phase-field crystal model to investigate the lattice systems of different anisotropic parameters and orientations

    Science.gov (United States)

    Kundin, Julia; Ajmal Choudhary, Muhammad

    2017-07-01

    In this article, we present the recent advances in the development of the anisotropic phase-field crystal (APFC) model. These advances are important in basic researches for multiferroic and thermoelectric materials with anisotropic crystal lattices and in thin-film applications. We start by providing a general description of the model derived in our previous studies based on the crystal symmetry and the microscopic dynamical density functional theory for anisotropic interactions and show that there exist only two possible degrees of freedom for the anisotropic lattices which are described by two independent parameters. New findings concerning the applications of the APFC model for the estimation of the elastic modules of anisotropic systems including sheared and stretched lattices as well as for the investigation of the heterogeneous thin film growth are described. The simulation results demonstrate the strong dependency of the misfit dislocation formation during the film growth on the anisotropy and reveal the asymmetric behavior in the cases of positive and negative misfits. We also present the development of the amplitude representation for the full APFC model of two orientation variants and show the relationship between the wave vectors and the base angles of the anisotropic lattices.

  7. Mixed parentage

    DEFF Research Database (Denmark)

    Bang Appel, Helene; Singla, Rashmi

    2016-01-01

    Despite an increase in cross border intimate relationships and children of mixed parentage, there is little mention or scholarship about them in the area of childhood and migrancy in the Nordic countries. The international literature implies historical pathologisation, contestation and current...... complex paradigms regarding these children. This chapter explores how children of mixed parentage negotiate their identities in the Danish context, where statistically and socially there are no widely acceptable terms for categorizing them. To this purpose, an empirical qualitative in...

  8. PURCELL EFFECT IN EXTREMELY ANISOTROPIC ELLIPTIC METAMATERIALS

    Directory of Open Access Journals (Sweden)

    Alexander V. Chebykin

    2014-11-01

    Full Text Available The paper deals with theoretical demonstration of Purcell effect in extremely anisotropic metamaterials with elliptical isofrequency surface. This effect is free from association with divergence in density of states unlike the case of hyperbolic metamaterials. It is shown that a large Purcell factor can be observed without excitation of modes with large wave vectors in one direction, and the component of the wave vector normal to the layers is less than k0. For these materials the possibility is given for increasing of the power radiated in the medium, as well as the power radiated from material into free space across the medium border situated transversely to the layers. We have investigated isofrequency contours and the dependence of Purcell factor from the frequency for infinite layered metamaterial structure. In the visible light range strong spatial dispersion gives no possibility to obtain enhancement of spontaneous emission in metamaterial with unit cell which consists of two layers. This effect can be achieved in periodic metal-dielectric layered nanostructures with a unit cell containing two different metallic layers and two dielectric ones. Analysis of the dependences for Purcell factor from the frequency shows that the spontaneous emission is enhanced by a factor of ten or more only for dipole orientation along metamaterial layers, but in the case of the transverse orientation radiation can be enhanced only 2-3 times at most. The results can be used to create a new type of metamaterials with elliptical isofrequency contours, providing a more efficient light emission in the far field.

  9. In-plane microwave dielectric properties of paraelectric barium strontium titanate thin films with anisotropic epitaxy

    Science.gov (United States)

    Simon, W. K.; Akdogan, E. K.; Safari, A.; Bellotti, J. A.

    2005-08-01

    In-plane dielectric properties of ⟨110⟩ oriented epitaxial (Ba0.60Sr0.40)TiO3 thin films in the thickness range from 25-1200nm have been investigated under the influence of anisotropic epitaxial strains from ⟨100⟩ NdGaO3 substrates. The measured dielectric properties show strong residual strain and in-plane directional dependence. Below 150nm film thickness, there appears to be a phase transition due to the anisotropic nature of the misfit strain relaxation. In-plane relative permittivity is found to vary from as much as 500-150 along [11¯0] and [001] respectively, in 600nm thick films, and from 75 to 500 overall. Tunability was found to vary from as much as 54% to 20% in all films and directions, and in a given film the best tunability is observed along the compressed axis in a mixed strain state, 54% along [11¯0] in the 600nm film for example.

  10. 2D seismic reflection tomography in strongly anisotropic media

    Science.gov (United States)

    Huang, Guangnan; Zhou, Bing; Li, Hongxi; Zhang, Hua; Li, Zelin

    2014-12-01

    Seismic traveltime tomography is an effective method to reconstruct underground anisotropic parameters. Currently, most anisotropic tomographic methods were developed under the assumption of weak anisotropy. The tomographic method proposed here can be implemented for imaging subsurface targets in strongly anisotropic media with a known tilted symmetry axis, since the adopted ray tracing method is suitable for anisotropic media with arbitrary degree. There are three kinds of reflection waves (qP, qSV and qSH waves) that were separately used to invert the blocky abnormal body model. The reflection traveltime tomographiy is developed here because a surface observation system is the most economical and practical way compared with crosswell and VSP. The numerical examples show that the traveltimes of qP reflection wave have inverted parameters {{c}11},{{c}13},{{c}33} \\text{and} {{c}44} successfully. Traveltimes of qSV reflection wave have inverted parameters {{c}11},{{c}33} \\text{and} {{c}44} successfully, with the exception of the {{c}13}, since it is less sensitive than other parameters. Traveltimes of qSH reflection wave also have inverted parameters {{c}44} \\text{and} {{c}66} successfully. In addition, we find that the velocity sensitivity functions (derivatives of phase velocity with respect to elastic moduli parameters) and raypath illuminating angles have a great influence on the qualities of tomograms according to the inversion of theoretical models. Finally, the numerical examples confirm that the reflection traveltime tomography can be applied to invert strongly anisotropic models.

  11. Formulation of cross-anisotropic failure criterion for soils

    Directory of Open Access Journals (Sweden)

    Yi-fei Sun

    2013-10-01

    Full Text Available Inherently anisotropic soil fabric has a considerable influence on soil strength. To model this kind of inherent anisotropy, a three-dimensional anisotropic failure criterion was proposed, employing a scalar-valued anisotropic variable and a modified general threedimensional isotropic failure criterion. The scalar-valued anisotropic variable in all sectors of the deviatoric plane was defined by correlating a normalized stress tensor with a normalized fabric tensor. Detailed comparison between the available experimental data and the corresponding model predictions in the deviatoric plane was conducted. The proposed failure criterion was shown to well predict the failure behavior in all sectors, especially in sector II with the Lode angle ranging between 60° and 120°, where the prediction was almost in accordance with test data. However, it was also observed that the proposed criterion overestimated the strength of dense Santa Monica Beach sand in sector III where the intermediate principal stress ratio b varied from approximately 0.2 to 0.8, and slightly underestimated the strength when b was between approximately 0.8 and 1. The difference between the model predictions and experimental data was due to the occurrence of shear bending, which might reduce the measured strength. Therefore, the proposed anisotropic failure criterion has a strong ability to characterize the failure behavior of various soils and potentially allows a better description of the influence of the loading direction with respect to the soil fabric.

  12. Mixed Movements

    DEFF Research Database (Denmark)

    Brabrand, Helle

    2010-01-01

    levels than those related to building, and this exploration is a special challenge and competence implicit artistic development work. The project Mixed Movements generates drawing-material, not primary as representation, but as a performance-based media, making the body being-in-the-media felt and appear......Mixed Movements is a research project engaged in performance-based architectural drawing. Architectonic implementation questions relations between the human body and a body of architecture by the different ways we handle drawing materials. A drawing may explore architectonic problems at other...

  13. 3-D waveform tomography sensitivity kernels for anisotropic media

    KAUST Repository

    Djebbi, Ramzi

    2014-01-01

    The complications in anisotropic multi-parameter inversion lie in the trade-off between the different anisotropy parameters. We compute the tomographic waveform sensitivity kernels for a VTI acoustic medium perturbation as a tool to investigate this ambiguity between the different parameters. We use dynamic ray tracing to efficiently handle the expensive computational cost for 3-D anisotropic models. Ray tracing provides also the ray direction information necessary for conditioning the sensitivity kernels to handle anisotropy. The NMO velocity and η parameter kernels showed a maximum sensitivity for diving waves which results in a relevant choice of those parameters in wave equation tomography. The δ parameter kernel showed zero sensitivity; therefore it can serve as a secondary parameter to fit the amplitude in the acoustic anisotropic inversion. Considering the limited penetration depth of diving waves, migration velocity analysis based kernels are introduced to fix the depth ambiguity with reflections and compute sensitivity maps in the deeper parts of the model.

  14. Anomalously large anisotropic magnetoresistance in a perovskite manganite.

    Science.gov (United States)

    Li, Run-Wei; Wang, Huabing; Wang, Xuewen; Yu, X Z; Matsui, Y; Cheng, Zhao-Hua; Shen, Bao-Gen; Plummer, E Ward; Zhang, Jiandi

    2009-08-25

    The signature of correlated electron materials (CEMs) is the coupling between spin, charge, orbital and lattice resulting in exotic functionality. This complexity is directly responsible for their tunability. We demonstrate here that the broken symmetry, through cubic to orthorhombic distortion in the lattice structure in a prototype manganite single crystal, La(0.69)Ca(0.31)MnO(3), leads to an anisotropic magneto-elastic response to an external field, and consequently to remarkable magneto-transport behavior. An anomalous anisotropic magnetoresistance (AMR) effect occurs close to the metal-insulator transition (MIT) in the system, showing a direct correlation with the anisotropic field-tuned MIT in the system and can be understood by means of a simple phenomenological model. A small crystalline anisotropy stimulates a "colossal" AMR near the MIT phase boundary of the system, thus revealing the intimate interplay between magneto- and electronic-crystalline couplings.

  15. Electromagnetic waves in uniaxial anisotropic chiral waveguides in magnetized plasma

    Science.gov (United States)

    Ghaffar, A.; Alkanhal, Majeed A. S.

    2015-07-01

    The characteristics of guided modes in circular waveguides of a uniaxial anisotropic chiral core and a cladding filled with anisotropic plasma are presented. The cladding region is assumed to be infinitely extended with an external applied magnetic field oriented along the direction of propagation in the waveguide. The characteristics equation for the modes in this waveguide are obtained. The variations of the propagation properties with the plasma parameters, chiral parameters, and the cyclotron frequency of plasma have been investigated. Particularly, the effects of the chirality and the cyclotron frequency of plasma on the magnitude and orientation of the energy flux of the guided modes for three kinds of uniaxial anisotropic chiral media have been numerically investigated. Comparisons of the computed results of the presented formulations with published results for some special cases confirm the accuracy of the presented analyses.

  16. Detection of the default mode network by an anisotropic analysis

    Science.gov (United States)

    Forero, Aura; Romero, Eduardo

    2017-11-01

    This document presents a proposal devoted to improve the detection of the default mode network (DMN) in resting state functional magnetic resonance imaging in noisy conditions caused by head movement. The proposed approach is inspired by the hierarchical treatment of information, in particular at the level of the brain basal ganglia. Essentially, the fact that information must be selected and reduced suggests propagation of information in the Central Nervous System (CNS) is anisotropic. Under this hypothesis, the reconstruction of information of activation should follow an anisotropic pattern. In this work, an anisotropic filter is used to recover the DMN that is perturbed by simulated motion artifacts. Results obtained show this approach outperforms the state-of-the-art methods by 5.93% PSNR.

  17. Anisotropic spreading of liquid metal on a rough intermetallic surface

    Directory of Open Access Journals (Sweden)

    Liu Wen

    2011-01-01

    Full Text Available An anisotropic wicking of molten Sn-Pb solder over an intermetallic rough surface has been studied. The phenomenon features preferential spreading and forming of an elliptical spread domain. A theoretically formulated model was established to predict the ratio of the wicking distance along the long axis (rx to that along the short axis (ry of the final wicking pattern. The phenomenon was simultaneously experimentally observed and recorded with a hotstage microscopy technique. The anisotropic wicking is established to be caused by a non-uniform topography of surface micro structures as opposed to an isotropic wicking on an intermetallic surface with uniformly distributed surface micro features. The relative deviation between the theoretically predicted rx/ry ratio and the corresponding average experimental value is 5%. Hence, the small margin of error confirms the validity of the proposed theoretical model of anisotropic wicking.

  18. Investigation of anisotropic scattering for optical tomography in biological tissues

    International Nuclear Information System (INIS)

    Mercimek, M.; Yildirim, H.; Geckinli, M.; Aydin, M.; Aydin, E. D.

    2009-01-01

    Photons with wavelengths in near infrared region are used in optical tomography. Radiation transport theory should be preferred instead of diffusion theory for numerical modelling of photon migration in biological tissues, where diffusion theory is invalid. For example, diffusion theory is not sufficient in the regions of close to boundaries, sources or sinks and highly absorbing or void-like media. Also anisotropic scattering must be considered in the numerical models since scattering is generally highly anisotropic in biological tissues. In addition to the absorption and scattering coefficients, a suitable phase function must be known in anisotropic scattering study. Here we have compared scattering phase functions for anisotropy. Then we have calculated Legendre moments which are necessary for the implementation of anisotropy factors into the transport code, PARTISN. Discrete ordinates method (SN) has been used in the transport calculations. We have obtained solutions first a homogeneous and then heterogeneous medium.

  19. Anomalously large anisotropic magnetoresistance in a perovskite manganite

    Science.gov (United States)

    Li, Run-Wei; Wang, Huabing; Wang, Xuewen; Yu, X. Z.; Matsui, Y.; Cheng, Zhao-Hua; Shen, Bao-Gen; Plummer, E. Ward; Zhang, Jiandi

    2009-01-01

    The signature of correlated electron materials (CEMs) is the coupling between spin, charge, orbital and lattice resulting in exotic functionality. This complexity is directly responsible for their tunability. We demonstrate here that the broken symmetry, through cubic to orthorhombic distortion in the lattice structure in a prototype manganite single crystal, La0.69Ca0.31MnO3, leads to an anisotropic magneto-elastic response to an external field, and consequently to remarkable magneto-transport behavior. An anomalous anisotropic magnetoresistance (AMR) effect occurs close to the metal-insulator transition (MIT) in the system, showing a direct correlation with the anisotropic field-tuned MIT in the system and can be understood by means of a simple phenomenological model. A small crystalline anisotropy stimulates a “colossal” AMR near the MIT phase boundary of the system, thus revealing the intimate interplay between magneto- and electronic-crystalline couplings. PMID:19706504

  20. Nonlinear, anisotropic, and giant photoconductivity in intrinsic and doped graphene

    Science.gov (United States)

    Singh, Ashutosh; Ghosh, Saikat; Agarwal, Amit

    2018-01-01

    We present a framework to calculate the anisotropic and nonlinear photoconductivity for two band systems with application to graphene. In contrast to the usual perturbative (second order in the optical field strength) techniques, we calculate photoconductivity to all orders in the optical field strength. In particular, for graphene, we find the photoresponse to be giant (at large optical field strengths) and anisotropic. The anisotropic photoresponse in graphene is correlated with polarization of the incident field, with the response being similar to that of a half-wave plate. We predict that the anisotropy in the simultaneous measurement of longitudinal (σx x) and transverse (σy x) photoconductivity, with four probes, offers a unique experimental signature of the photovoltaic response, distinguishing it from the thermal-Seebeck and bolometric effects in photoresponse.

  1. Modeling of charged anisotropic compact stars in general relativity

    Energy Technology Data Exchange (ETDEWEB)

    Dayanandan, Baiju; Maurya, S.K.; T, Smitha T. [University of Nizwa, Department of Mathematical and Physical Sciences, College of Arts and Science, Nizwa (Oman)

    2017-06-15

    A charged compact star model has been determined for anisotropic fluid distribution. We have solved the Einstein-Maxwell field equations to construct the charged compact star model by using the radial pressure, the metric function e{sup λ} and the electric charge function. The generic charged anisotropic solution is verified by exploring different physical conditions like causality condition, mass-radius relation and stability of the solution (via the adiabatic index, TOV equations and the Herrera cracking concept). It is observed that the present charged anisotropic compact star model is compatible with the star PSR 1937+21. Moreover, we also presented the EOS ρ = f(p) for the present charged compact star model. (orig.)

  2. Self-force on dislocation segments in anisotropic crystals

    International Nuclear Information System (INIS)

    Fitzgerald, S P; Aubry, S

    2010-01-01

    A dislocation segment in a crystal experiences a 'self-force', by virtue of the orientation dependence of its elastic energy. If the crystal is elastically isotropic, this force is manifested as a couple acting to rotate the segment toward the lower energy of the pure screw orientation (i.e. acting to align the dislocation line with its Burgers vector). If the crystal is anisotropic, there are additional contributions to the couple, arising from the more complex energy landscape of the lattice itself. These effects can strongly influence the dynamic evolution of dislocation networks, and via their governing role in dislocation multiplication phenomena, control plastic flow in metals. In this paper we develop a model for dislocation self-forces in a general anisotropic crystal, and briefly consider the technologically important example of α-iron, which becomes increasingly anisotropic as the temperature approaches that of the α-γ phase transition at 912 0 C.

  3. Combined gating and trafficking defect in Kv11.1 manifests as a malignant long QT syndrome phenotype in a large Danish p.F29L founder family

    DEFF Research Database (Denmark)

    Kanters, Jørgen K.; Skibsbye, Lasse; Hedley, Paula L.

    2015-01-01

    Background: Congenital long QT syndrome (LQTS) is a hereditary cardiac channelopathy characterized by delayedventricular repolarization, syncope, torsades de pointes and sudden cardiac death. Thirty-three members of fi ve apparently‘ unrelated ’Danish families carry the KCNH2:c.87C A; p.F29L...

  4. Mixed marriages

    Directory of Open Access Journals (Sweden)

    Crnić-Pejović Marija

    2005-01-01

    Full Text Available Until the II World War, the population of the Boka Kotorska Bay was a mixture of Orthodox and Catholic confessions: approximately two thirds of the population was Orthodox, while one third belonged to the Catholics. In spite of the religious affiliation, mixed marriages were relatively often between these two groups. Based on a research in archives, this paper deals with such mixed marriages, formed mostly in 18th and 19th century, in the area of Herceg Novi. The second half of 19th century witnessed 639 of marriages, or 12,78 marriages per year, out of which 72 were mixed or 8,87%. In this particular period, 64 Catholic males married Orthodox females, while only 8 Orthodox males married Catholic females. The Church influence on the society was significant, including issues related to marriage, which sometimes created troubles for mixed marriages; however, positive civil and church regulations supported mixed marriages. Marriages between people of a different religious confession thus created wider kinship affiliations, which in turn enhanced religious tolerance, intertwining of different cultures and customs, and acceptance of different political and social views. The tolerance therefore affected political and social turmoil especially in troubled times, which made many issues easier: troubled issues were solved more rationally, and there were not so many persecutions based on someone’s religious affiliation. We need a wider perspective and a broader research on the Boka Kotorska Bay in order to understand how marriages and kinship ties affected a way of life and intertwining of cultural models of the East and West.

  5. Anisotropic third-moment estimates of the energy cascade in solar wind turbulence using multispacecraft data.

    Science.gov (United States)

    Osman, K T; Wan, M; Matthaeus, W H; Weygand, J M; Dasso, S

    2011-10-14

    The first direct determination of the inertial range energy cascade rate, using an anisotropic form of Yaglom's law for magnetohydrodynamic turbulence, is obtained in the solar wind with multispacecraft measurements. The two-point mixed third-order structure functions of Elsässer fluctuations are integrated over a sphere in magnetic field-aligned coordinates, and the result is consistent with a linear scaling. Therefore, volume integrated heating and cascade rates are obtained that, unlike previous studies, make only limited assumptions about the underlying spectral geometry of solar wind turbulence. These results confirm the turbulent nature of magnetic and velocity field fluctuations in the low frequency limit, and could supply the energy necessary to account for the nonadiabatic heating of the solar wind.

  6. A numerical analysis of an anisotropic phase-field model for binary-fluid mixtures in the presence of magnetic-field

    OpenAIRE

    Belmiloudi , Aziz; Rasheed , Amer

    2015-01-01

    In this paper we propose a numerical scheme and perform its numerical analysis devoted to an anisotropic phase-field model with convection under the influence of magnetic field for the isother-mal solidification of binary mixtures in two-dimensional geometry. Precisely, the numerical stability and error analysis of this approximation scheme which is based on mixed finite-element method are performed. The particular application of a nickelcopper (NiCu) binary alloy, with real physical paramete...

  7. Lower critical field of an anisotropic type-II superconductor

    International Nuclear Information System (INIS)

    Klemm, R.A.; Clem, J.R.

    1980-01-01

    We consider the Ginzburg-Landau free energy of the anisotropic mass form in the presence of a magnetic field of arbitrary fixed direction. It is shown that the free energy may be transformed into the isotropic Ginsburg-Landau form with a kappa that depends upon the direction of the magnetic induction B relative to the crystal lattice. The lower critical field H/sub c/1 is then found for arbitrary direction of B. For highly anisotropic crystals the angular dependence of H/sub c/1 can exhibit a discontinuity or a cusp. The special case of a crystal with uniaxial symmetry is considered in detail

  8. Anisotropic extension of Finch and Skea stellar model

    Science.gov (United States)

    Sharma, Ranjan; Das, Shyam; Thirukkanesh, S.

    2017-12-01

    In this paper, the spacetime geometry of Finch and Skea [Class. Quantum Gravity 6:467, 1989] has been utilized to obtain closed-form solutions for a spherically symmetric anisotropic matter distribution. By examining its physical admissibility, we have shown that the class of solutions can be used as viable models for observed pulsars. In particular, a specific class of solutions can be used as an `anisotropic switch' to examine the impact of anisotropy on the gross physical properties of a stellar configuration. Accordingly, the mass-radius relationship has been analyzed.

  9. Anisotropic Liquid Microcapsules from Biomimetic Self-Folding Polymer Films.

    Science.gov (United States)

    Zakharchenko, Svetlana; Ionov, Leonid

    2015-06-17

    We demonstrated a novel approach for the fabrication of anisotropic capsules with liquid content using biomimetic self-folding thermoresponsive polymer films. The behavior of self-folding films is very similar to actuation in plants, where nonhomogenous swelling results in complex movements such as twisting, bending, or folding. This approach allows the design of anisotropic liquid capsules with rodlike and dumbbell-like morphologies. We found that these capsules are able to assemble into different complex structures, such as nematic-like one and 3D network depending on their morphology.

  10. Remarks on anisotropy of inertia in an anisotropic cosmos

    Science.gov (United States)

    Treder, Hans-Juergen

    1992-03-01

    The astronomical and physical meaning of the anisotropy of inertia is analyzed with respect to the relativity of inertia and anisotropic distributions of gravitating matter in the universe. Attention is given to the theoretical compatibility of the anisotropy of inertial masses with Mach's principle of the relativity of inertia and the Mach-Einstein doctrine of general relativity. Mach's principle does not imply anisotropy of inertial masses in an anisotropic universe, and the isotropy of cosmological mass is supported by the Mach-Einstein theories.

  11. Anisotropic behavior of quantum transport in graphene superlattices

    DEFF Research Database (Denmark)

    Pedersen, Jesper Goor; Cummings, Aron W.; Roche, Stephan

    2014-01-01

    We report on the possibility to generate highly anisotropic quantum conductivity in disordered graphene-based superlattices. Our quantum simulations, based on an efficient real-space implementation of the Kubo-Greenwood formula, show that in disordered graphene superlattices the strength of multi...... orders of magnitude, and suggesting the possibility of building graphene electronic circuits based on the unique properties of chiral massless Dirac fermions in graphene.......We report on the possibility to generate highly anisotropic quantum conductivity in disordered graphene-based superlattices. Our quantum simulations, based on an efficient real-space implementation of the Kubo-Greenwood formula, show that in disordered graphene superlattices the strength...

  12. All spherically symmetric charged anisotropic solutions for compact stars

    Energy Technology Data Exchange (ETDEWEB)

    Maurya, S.K. [University of Nizwa, Department of Mathematical and Physical Sciences, College of Arts and Science, Nizwa (Oman); Gupta, Y.K. [Raj Kumar Goel Institute of Technology, Department of Mathematics, Ghaziabad, UP (India); Ray, Saibal [Government College of Engineering and Ceramic Technology, Department of Physics, Kolkata, West Bengal (India)

    2017-06-15

    In the present paper we develop an algorithm for all spherically symmetric anisotropic charged fluid distributions. Considering a new source function ν(r) we find a set of solutions which is physically well behaved and represents compact stellar models. A detailed study specifically shows that the models actually correspond to strange stars in terms of their mass and radius. In this connection we investigate several physical properties like energy conditions, stability, mass-radius ratio, electric charge content, anisotropic nature and surface redshift through graphical plots and mathematical calculations. All the features from these studies are in excellent agreement with the already available evidence in theory as well as observations. (orig.)

  13. Correlation theory of crystal field and anisotropic exchange effects

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1985-01-01

    A general theory for including correlation effects in static and dynamic properties is presented in terms of Raccah or Stevens operators. It is explicitly developed for general crystal fields and anisotropic interactions and systems with several sublattices, like the rare earth compounds. The the......A general theory for including correlation effects in static and dynamic properties is presented in terms of Raccah or Stevens operators. It is explicitly developed for general crystal fields and anisotropic interactions and systems with several sublattices, like the rare earth compounds...... on the susceptibility, the first and second moment frequencies and the line shape are calculated self-consistently....

  14. Tunable waveguide bends with graphene-based anisotropic metamaterials

    KAUST Repository

    Chen, Zhao-xian

    2016-01-15

    We design tunable waveguide bends filled with graphene-based anisotropic metamaterials to achieve a nearly perfect bending effect. The anisotropic properties of the metamaterials can be described by the effective medium theory. The nearly perfect bending effect is demonstrated by finite element simulations of various structures with different bending curvatures and shapes. This effect is attributed to zero effective permittivity along the direction of propagation and matched effective impedance at the interfaces between the bending part and the dielectric waveguides. We envisage that the design will be applicable in the far-infrared and terahertz frequency ranges owing to the tunable dielectric responses of graphene.

  15. Integral superposition of paraxial Gaussian beams in inhomogeneous anisotropic layered structures in Cartesian coordinates

    Czech Academy of Sciences Publication Activity Database

    Červený, V.; Pšenčík, Ivan

    2015-01-01

    Roč. 25, - (2015), s. 109-155 ISSN 2336-3827 Institutional support: RVO:67985530 Keywords : integral superposition of paraxial Gaussian beams * inhomogeneous anisotropic media * S waves in weakly anisotropic media Subject RIV: DC - Siesmology, Volcanology, Earth Structure

  16. A Morphing framework to couple non-local and local anisotropic continua

    KAUST Repository

    Azdoud, Yan

    2013-05-01

    In this article, we develop a method to couple anisotropic local continua with anisotropic non-local continua with central long-range forces. First, we describe anisotropic non-local models based on spherical harmonic descriptions. We then derive compatible classic continuum models. Finally, we apply the morphing method to these anisotropic non-local models and present three-dimensional numerical examples to validate the efficiency of the technique. © 2013 Elsevier Ltd. All rights reserved.

  17. Ray-optics analysis of inhomogeneous optically anisotropic media

    NARCIS (Netherlands)

    Sluijter, M.

    2010-01-01

    When the optical behavior of light in a medium depends on the direction in which light is traveling, the medium is called optically anisotropic. Light is an electromagnetic wave and in this thesis, we discuss the electromagnetic theory on optical anisotropy. We do this with the assumption that the

  18. On the origins of the anisotropic mechanical behaviour of extruded ...

    Indian Academy of Sciences (India)

    Mater. Sci., Vol. 40, No. 2, April 2017, pp. 395–406. c Indian Academy of Sciences. DOI 10.1007/s12034-017-1383-3. On the origins of the anisotropic mechanical behaviour of extruded. AA2017 aluminium alloy. A MAY. Laboratoire Génie des Matériaux, Ecole Militaire Polytechnique, BP 17, Bordj El Bahri 16046, Algeria.

  19. Negative index of refraction in anisotropic nonmagnetic materials

    Czech Academy of Sciences Publication Activity Database

    Dvořák, Vladimír; Kužel, Petr

    2006-01-01

    Roč. 338, - (2006), s. 195-203 ISSN 0015-0193 R&D Projects: GA AV ČR 1ET300100401 Institutional research plan: CEZ:AV0Z10100520 Keywords : anisotropic dielectric * negative refractive index * surface modes * guided modes Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.389, year: 2006

  20. Finite-difference modelling of anisotropic wave scattering in discrete ...

    Indian Academy of Sciences (India)

    A M Ekanem

    2018-04-05

    Apr 5, 2018 ... fractured hydrocarbon reservoirs to complement the use of other seismic attributes. Despite the con- certed effort in research and development related to seismic characterization of fractured reservoirs using anisotropic wave scattering, pragmatic uti- lization of this attribute in geophysical exploration.

  1. Autofocus imaging : Experimental results in an anisotropic austenitic weld

    NARCIS (Netherlands)

    Zhang, J.; Drinkwater, B.W.; Wilcox, P.D.; Hunter, A.J.

    2012-01-01

    The quality of an ultrasonic array image, especially for anisotropic material, depends on accurate information about acoustic properties. Inaccuracy of acoustic properties causes image degradation, e.g., blurring, errors in locating of reflectors and introduction of artifacts. In this paper, for an

  2. On the interpretation of time-resolved anisotropic diffraction patterns

    DEFF Research Database (Denmark)

    Lorenz, Ulf; Møller, Klaus Braagaard; Henriksen, Niels Engholm

    2010-01-01

    In this paper, we review existing systematic treatments for the interpretation of anisotropic diffraction patterns from partially aligned symmetric top molecules. Such patterns arise in the context of time-resolved diffraction experiments. We calculate diffraction patterns for ground-state Na...

  3. On the origins of the anisotropic mechanical behaviour of extruded ...

    Indian Academy of Sciences (India)

    This paper presents some experimental investigations about the origins of the anisotropic behaviour in cyclic loadings of AA2017 aluminium alloy. In the first step, fatigue damage evolutions were quantified for controlled proportional cyclic loadings in axial and shear directions. In this stage, the aim was to confirm the ...

  4. Anisotropic cosmological models and generalized scalar tensor theory

    Indian Academy of Sciences (India)

    Abstract. In this paper generalized scalar tensor theory has been considered in the background of anisotropic cosmological models, namely, axially symmetric Bianchi-I, Bianchi-III and Kortowski–. Sachs space-time. For bulk viscous fluid, both exponential and power-law solutions have been stud- ied and some assumptions ...

  5. Anisotropic cosmological models and generalized scalar tensor theory

    Indian Academy of Sciences (India)

    In this paper generalized scalar tensor theory has been considered in the background of anisotropic cosmological models, namely, axially symmetric Bianchi-I, Bianchi-III and Kortowski–Sachs space-time. For bulk viscous fluid, both exponential and power-law solutions have been studied and some assumptions among the ...

  6. Propagation of waves in a gravitating and rotating anisotropic heat ...

    African Journals Online (AJOL)

    Bheema

    (1956) equations neglecting the heat flux vector. Gravitational instability on propagation of magnetohydrodynamic (MHD) waves in astrophysical plasma is investigated by Alemayehu and Tessema (2013a) by considering the effect of gravitational instability and viscosity with anisotropic pressure tensor and heat conducting.

  7. Three anisotropic benchmark problems for adaptive finite element methods

    Czech Academy of Sciences Publication Activity Database

    Šolín, Pavel; Čertík, O.; Korous, L.

    2013-01-01

    Roč. 219, č. 13 (2013), s. 7286-7295 ISSN 0096-3003 R&D Projects: GA AV ČR IAA100760702 Institutional support: RVO:61388998 Keywords : benchmark problem * anisotropic solution * boundary layer Subject RIV: BA - General Mathematics Impact factor: 1.600, year: 2013

  8. Metastability thresholds for anisotropic bootstrap percolation in three dimensions

    NARCIS (Netherlands)

    Van Enter, A.C.D.; Fey, A.

    2012-01-01

    In this paper we analyze several anisotropic bootstrap percolation models in three dimensions. We present the order of magnitude for the metastability thresholds for a fairly general class of models. In our proofs, we use an adaptation of the technique of dimensional reduction. We find that the

  9. Metastability Thresholds for Anisotropic Bootstrap Percolation in Three Dimensions

    NARCIS (Netherlands)

    Van Enter, A.C.D.; Fey, A.

    2012-01-01

    In this paper we analyze several anisotropic bootstrap percolation models in three dimensions. We present the order of magnitude for the metastability thresholds for a fairly general class of models. In our proofs, we use an adaptation of the technique of dimensional reduction. We find that the

  10. Finite-size effects for anisotropic bootstrap percolation : Logarithmic corrections

    NARCIS (Netherlands)

    van Enter, Aernout C. D.; Hulshof, Tim

    In this note we analyse an anisotropic, two-dimensional bootstrap percolation model introduced by Gravner and Griffeath. We present upper and lower bounds on the finite-size effects. We discuss the similarities with the semi-oriented model introduced by Duarte.

  11. Metastability Thresholds for Anisotropic Bootstrap Percolation in Three Dimensions

    NARCIS (Netherlands)

    Enter, Aernout C.D. van; Fey, Anne

    In this paper we analyze several anisotropic bootstrap percolation models in three dimensions. We present the order of magnitude for the metastability thresholds for a fairly general class of models. In our proofs, we use an adaptation of the technique of dimensional reduction. We find that the

  12. Some dynamical properties of anisotropic collisionless stellar systems

    International Nuclear Information System (INIS)

    Bertin, G.; Pegoraro, F.

    1989-01-01

    The linear stability analysis of collisionless anisotropic spherical stellar systems presents many unresolved issues. Planning to study the stability of a simple and astrophysically interesting equilibrium seuence ∞ for such stellar systems, we describe here some analytical characterizations of the ∞-distribution functions, formulate the linearized equations for stability, and discuss the relevant boundary conditions. (author). 19 refs.; 1 tab

  13. New exact models for anisotropic matter with electric field

    Indian Academy of Sciences (India)

    Jefta M Sunzu

    2017-09-05

    Sep 5, 2017 ... In our models, we consider the stellar object that is anisotropic and charged with linear equation of state consistent with quark stars. ... Einstein–Maxwell equations; anisotropy; charged matter; equation of state. PACS Nos 04.20. .... Sunzu et al [3] which was a general cubic polynomial. However, our choice ...

  14. Wave propagation in a general anisotropic poroelastic medium ...

    Indian Academy of Sciences (India)

    equations (Auriault et al 1985) in terms of solid displacement and fluid pressure, whereas Biot's equations were in terms of displacements of both the solid and fluid phases. Homogenisation has proven that .... (8) to (10) imply that, in homogenisation approach, the anisotropic inertial coupling is hiding in the tensor {ˆρij}.

  15. Exact anisotropic sphere with polytropic equation of state

    Indian Academy of Sciences (India)

    Abstract. We study static spherically symmetric spacetime to describe compact objects with anisotropic matter distribution. We express the system of Einstein field equations as a new system of differential equations using a coordinate transformation, and then write the system in another form with polytropic equation of state ...

  16. Anisotropic Born-Mayer potential in lattice dynamics of Vanadium

    International Nuclear Information System (INIS)

    Onwuagba, B.N.

    1988-01-01

    A microscopic theory of the lattice dynamics of the transition metal vanadium is developed based on the Animalu's transition metal model potential (TMMP). The Born-Mayer potential associated with the distribution of the transition metal d-electrons is treated as anisotropic. Good agreement with experimental phonon dispersion curves longitudinal branches in the [111] direction

  17. Anisotropic strain and phonon deformation potentials in GaN

    International Nuclear Information System (INIS)

    Darakchieva, V.; Arwin, H.; Paskov, P. P.; Monemar, B.; Paskova, T.; Hommel, D.; Schubert, M.; Heuken, M.; Off, J.; Scholz, F.; Haskell, B. A.; Fini, P. T.; Speck, J. S.; Nakamura, S.

    2007-01-01

    We report optical phonon frequency studies in anisotropically strained c-plane- and a-plane-oriented GaN films by generalized infrared spectroscopic ellipsometry and Raman scattering spectroscopy. The anisotropic strain in the films is obtained from high-resolution x-ray diffraction measurements. Experimental evidence for splitting of the GaN E 1 (TO), E 1 (LO), and E 2 phonons under anisotropic strain in the basal plane is presented, and their phonon deformation potentials c E 1 (TO) , c E 1 (LO) , and c E 2 are determined. A distinct correlation between anisotropic strain and the A 1 (TO) and E 1 (LO) frequencies of a-plane GaN films reveals the a A 1 (TO) , b A 1 (TO) , a E 1 (LO) , and b E 1 (LO) phonon deformation potentials. The a A 1 (TO) and b A 1 (TO) are found to be in very good agreement with previous results from Raman experiments [V. Yu. Davydov et al., J. Appl. Phys. 82, 5097 (1997)]. Our a A 1 (TO) and a E 1 (LO) phonon deformation potentials agree well with recently reported theoretical estimations [J.-M. Wagner and F. Bechstedt, Phys. Rev. B 66, 115202 (2002)], while b A 1 (TO) and b E 1 (LO) are found to be significantly larger than the theoretical values. A discussion of the observed differences is presented

  18. Double anisotropic electrically conductive flexible Janus-typed membranes.

    Science.gov (United States)

    Li, Xiaobing; Ma, Qianli; Tian, Jiao; Xi, Xue; Li, Dan; Dong, Xiangting; Yu, Wensheng; Wang, Xinlu; Wang, Jinxian; Liu, Guixia

    2017-12-07

    Novel type III anisotropic conductive films (ACFs), namely flexible Janus-typed membranes, were proposed, designed and fabricated for the first time. Flexible Janus-typed membranes composed of ordered Janus nanobelts were constructed by electrospinning, which simultaneously possess fluorescence and double electrically conductive anisotropy. For the fabrication of the Janus-typed membrane, Janus nanobelts comprising a conductive side and an insulative-fluorescent side were primarily fabricated, and then the Janus nanobelts are arranged into parallel arrays using an aluminum rotary drum as the collector to obtain a single anisotropically conductive film. Subsequently, a secondary electrospinning process was applied to the as-prepared single anisotropically conductive films to acquire the final Janus-typed membrane. For this Janus-typed membrane, namely its left-to-right structure, anisotropic electrical conduction synchronously exists on both sides, and furthermore, the two electrically conductive directions are perpendicular. By modulating the amount of Eu(BA) 3 phen complex and conducting polyaniline (PANI), the characteristics and intensity of the fluorescence-electricity dual-function in the membrane can be tuned. The high integration of this peculiar Janus-typed membrane with simultaneous double electrically conductive anisotropy-fluorescent dual-functionality is successfully realized in this study. This design philosophy and preparative technique will provide support for the design and construction of new types of special nanostructures with multi-functionality.

  19. Anisotropic cosmological models in f (R, T) theory of gravitation

    Indian Academy of Sciences (India)

    Bianchi spaces are useful tools for constructing spatially homogeneous and anisotropic cosmological models in general relativity and scalar–tensor theories of gravitation. Adhav [14] obtained exact solutions of the field equations for LRS. Bianchi type-I space-time with perfect fluid in the framework of f (R, T) theory of grav-.

  20. Anisotropic Bianchi-I universe with phantom field and cosmological ...

    Indian Academy of Sciences (India)

    We study an anisotropic Bianchi-I universe in the presence of a phantom field and a cosmological constant. Cosmological solutions are obtained when the kinetic energy of the phantom field is of the order of anisotropy and dominates over the potential energy of the field. The anisotropy of the universe decreases and the ...

  1. Gmax for Sand by Bender Elements at Anisotropic Stress States

    DEFF Research Database (Denmark)

    Bødker, L.

    1996-01-01

    elements for two types of sand and with void ratios varying from minimum to maximum. The tests performed are carried out in the Danish Triaxial Cell, and Gmax are determined at different isotropic and anisotropic stress states. The main result of the test program is that Gmax is primarily influenced...

  2. Charged anisotropic star on paraboloidal space-time

    Indian Academy of Sciences (India)

    ... is the central pressure. At the boundary of the star r = R, pr must vanish, which gives r = R as the radius of the star. This form of radial pressure is prescribed by Sharma and Ratanpal [18] to describe anisotropic stellar model admitting a quadratic equation of state on paraboloidal space-time. Equations (8) and (4) give ν =.

  3. New exact models for anisotropic matter with electric field

    Indian Academy of Sciences (India)

    2017-09-05

    Sep 5, 2017 ... We can also obtain particular anisotropic models obtained by Maharaj, Sunzu, and Ray. The exact solutions corresponding to our models are found explicitly in terms of elementary functions. The graphical plots generated for the matter variables and the electric field are well behaved. We also generate ...

  4. Anisotropic colloids: bulk phase behavior and equilibrium sedimentation

    NARCIS (Netherlands)

    Marechal, M.A.T.

    2009-01-01

    This thesis focuses on the phase behavior of anisotropically shaped (i.e. non-spherical) colloids using computer simulations. Only hard-core interactions between the colloids are taken into account to investigate the effects of shape alone. The bulk phase behavior of three different shapes of

  5. Surface waves in fibre-reinforced anisotropic elastic media

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Abstract. Though the decoupling of displacement potentials in case of fibre- reinfoced anisotropic elastic media is not possible in the general case, an attempt has been made to decouple the equation as a particular case. The assumptions made in this paper satisfy both set of equations formed by the displacement ...

  6. Fracture of anisotropic materials with plastic strain-gradient effects

    DEFF Research Database (Denmark)

    Legarth, Brian Nyvang

    2013-01-01

    A unit cell is adopted to numerically analyze the effect of plastic anisotropy on frac-ture evolution in a micro-reinforced fiber-composite. The matrix material exhibit size-effects and an anisotropic strain-gradient plasticity model accounting for such size-effects through a mate-rial length scale...

  7. Anisotropic Bianchi-I universe with phantom field and cosmological ...

    Indian Academy of Sciences (India)

    The anisotropy of the universe decreases and the universe transits to an isotropic flat FRW universe accommodating the present acceleration. A class of new cosmological solutions is obtained for an anisotropic universe in case an initial anisotropy exists which is bigger than the value determined by the parameter of the ...

  8. Angle-domain common-image gathers from anisotropic Gaussian ...

    Indian Academy of Sciences (India)

    s12040-016-0783-x. Angle-domain common-image gathers from anisotropic ..... are not flat. The test results demonstrate that anisotropy has a great influence on GB-PSDM in. VTI media, and ignoring anisotropy in migration may lead to obvious ...

  9. Exact anisotropic sphere with polytropic equation of state

    Indian Academy of Sciences (India)

    self-gravitating, static, isotropic fluid spheres when pressure explicitly depends on matter density, which invariably leads to non-integrable equations [32]. However, our treatment of anisotropic fluids with polytropic equation of state gets some flexibility in solving the. Einstein field equations with uncharged matter in static ...

  10. Dynamical anisotropic response of black phosphorus under magnetic field

    Science.gov (United States)

    Liu, Xuefeng; Lu, Wei; Zhou, Xiaoying; Zhou, Yang; Zhang, Chenglong; Lai, Jiawei; Ge, Shaofeng; Sekhar, M. Chandra; Jia, Shuang; Chang, Kai; Sun, Dong

    2018-04-01

    Black phosphorus (BP) has emerged as a promising material candidate for next generation electronic and optoelectronic devices due to its high mobility, tunable band gap and highly anisotropic properties. In this work, polarization resolved ultrafast mid-infrared transient reflection spectroscopy measurements are performed to study the dynamical anisotropic optical properties of BP under magnetic fields up to 9 T. The relaxation dynamics of photoexcited carrier is found to be insensitive to the applied magnetic field due to the broadening of the Landau levels and large effective mass of carriers. While the anisotropic optical response of BP decreases with increasing magnetic field, its enhancement due to the excitation of hot carriers is similar to that without magnetic field. These experimental results can be well interpreted by the magneto-optical conductivity of the Landau levels of BP thin film, based on an effective k · p Hamiltonian and linear response theory. These findings suggest attractive possibilities of multi-dimensional control of anisotropic response (AR) of BP with light, electric and magnetic field, which further introduces BP to the fantastic magnetic field sensitive applications.

  11. Theory of Spin Waves in Strongly Anisotropic Magnets

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker; Cooke, J. F.

    1976-01-01

    A new infinite-order perturbation approach to the theory of spin waves in strongly anisotropic magnets is introduced. The system is transformed into one with effective two-ion anisotropy and considerably reduced ground-state corrections. A general expression for the spin-wave energy, valid to any...

  12. Minimal Sampling for Effective Acquisition of Anisotropic BRDFs

    Czech Academy of Sciences Publication Activity Database

    Vávra, Radomír; Filip, Jiří

    2016-01-01

    Roč. 35, č. 7 (2016), s. 299-309 ISSN 0167-7055 R&D Projects: GA ČR(CZ) GA14-02652S Institutional support: RVO:67985556 Keywords : BRDF * anisotropic * measurement Subject RIV: BD - Theory of Information Impact factor: 1.611, year: 2016 http://library.utia.cas.cz/separaty/2016/RO/vavra-0463872.pdf

  13. Viscoelastic materials with anisotropic rigid particles: stress-deformation behavior

    NARCIS (Netherlands)

    Sagis, L.M.C.; Linden, van der E.

    2001-01-01

    In this paper we have derived constitutive equations for the stress tensor of a viscoelastic material with anisotropic rigid particles. We have assumed that the material has fading memory. The expressions are valid for slow and small deformations from equilibrium, and for systems that are nearly

  14. Wave velocities in a pre-stressed anisotropic elastic medium

    Indian Academy of Sciences (India)

    Modified Christoffel equations are derived for three-dimensional wave propagation in a general anisotropic medium under initial stress.The three roots of a cubic equation define the phase velocities of three quasi-waves in the medium.Analytical expressions are used to calculate the directional derivatives of phase ...

  15. Propagation of waves in a gravitating and rotating anisotropic heat ...

    African Journals Online (AJOL)

    An inviscid, unbounded, collisionless, gravitating, rotating and heat conducting anisotropic plasma medium which is drifting is considered. The medium is assumed to be embedded in a strong magnetic field. A general dispersion relation is derived using normal mode analysis and its various limiting cases are discussed, ...

  16. Finite-difference modelling of anisotropic wave scattering in discrete ...

    Indian Academy of Sciences (India)

    2

    attribute in geophysical exploration is still restricted perhaps as a result of the ambiguity in its. 51 quantification and difficulty in its interpretation in terms of rock properties (Jeng et al., 1999,. 52. MacBeth, 1999; Rongrong et al., 2006). Thus, the task of using anisotropic wave scattering for fracture. 53 prediction in the Earth's ...

  17. Fourth-order discrete anisotropic boundary-value problems

    Directory of Open Access Journals (Sweden)

    Maciej Leszczynski

    2015-09-01

    Full Text Available In this article we consider the fourth-order discrete anisotropic boundary value problem with both advance and retardation. We apply the direct method of the calculus of variations and the mountain pass technique to prove the existence of at least one and at least two solutions. Non-existence of non-trivial solutions is also undertaken.

  18. Prestack exploding reflector modelling and migration for anisotropic media

    KAUST Repository

    Alkhalifah, Tariq Ali

    2014-10-09

    The double-square-root equation is commonly used to image data by downward continuation using one-way depth extrapolation methods. A two-way time extrapolation of the double-square-root-derived phase operator allows for up and downgoing wavefields but suffers from an essential singularity for horizontally travelling waves. This singularity is also associated with an anisotropic version of the double-square-root extrapolator. Perturbation theory allows us to separate the isotropic contribution, as well as the singularity, from the anisotropic contribution to the operator. As a result, the anisotropic residual operator is free from such singularities and can be applied as a stand alone operator to correct for anisotropy. We can apply the residual anisotropy operator even if the original prestack wavefield was obtained using, for example, reverse-time migration. The residual correction is also useful for anisotropic parameter estimation. Applications to synthetic data demonstrate the accuracy of the new prestack modelling and migration approach. It also proves useful in approximately imaging the Vertical Transverse Isotropic Marmousi model.

  19. Angle-domain common-image gathers from anisotropic Gaussian ...

    Indian Academy of Sciences (India)

    An approach for extracting angle-domain common-image gathers (ADCIGs) from anisotropic Gaussian beam prestack depth migration (GB-PSDM) is presented in this paper. The propagation angle is calcu- lated in the process of migration using the real-value traveltime information of Gaussian beam. Based on the above ...

  20. Anisotropic properties of aligned SWNT modified poly (methyl ...

    Indian Academy of Sciences (India)

    The electrical and mechanical properties of PMMA/SWNT composite were studied as a function of SWNT orientation and concentration. The aligned SWNT modified PMMA/SWNT composite presented highly anisotropic properties. The experimental results showed that the electrical conductivity and mechanical properties of ...

  1. Surface waves in fibre-reinforced anisotropic elastic media

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    MS received 1 March 2002. Abstract. In the paper under discussion, the problem of surface waves in fibre- reinforced anisotropic elastic media has been studied. The authors express the plane strain displacement components in terms of two scalar potentials to decouple the plane motion into P and SV waves. In the present ...

  2. Crystal structure of vanadite: Refinement of anisotropic displacement parameters

    Czech Academy of Sciences Publication Activity Database

    Laufek, F.; Skála, Roman; Haloda, J.; Císařová, I.

    2006-01-01

    Roč. 51, 3-4 (2006), s. 271-275 ISSN 1210-8197 Institutional research plan: CEZ:AV0Z30130516 Keywords : anisotropic displacement parameter * crystal structure * single-crystal X-ray refinement * vanadinite Subject RIV: DB - Geology ; Mineralogy

  3. Finite-difference modelling of anisotropic wave scattering in discrete ...

    Indian Academy of Sciences (India)

    2

    cells containing equivalent anisotropic medium by the use of the linear slip equivalent model. Our. 16 results show ...... frequency regression predicted by equation (21) can be distorted by the effects of multiple scattering. 337 ..... other seismic attributes, at least for the relatively simple geometries of subsurface structure. 449.

  4. Brazilian Tensile Strength of Anisotropic Rocks: Review and New Insights

    Directory of Open Access Journals (Sweden)

    Tianshou Ma

    2018-01-01

    Full Text Available Strength anisotropy is one of the most distinct features of anisotropic rocks, and it also normally reveals strong anisotropy in Brazilian test Strength (“BtS”. Theoretical research on the “BtS” of anisotropic rocks is seldom performed, and in particular some significant factors, such as the anisotropic tensile strength of anisotropic rocks, the initial Brazilian disc fracture points, and the stress distribution on the Brazilian disc, are often ignored. The aim of the present paper is to review the state of the art in the experimental studies on the “BtS” of anisotropic rocks since the pioneering work was introduced in 1964, and to propose a novel theoretical method to underpin the failure mechanisms and predict the “BtS” of anisotropic rocks under Brazilian test conditions. The experimental data of Longmaxi Shale-I and Jixi Coal were utilized to verify the proposed method. The results show the predicted “BtS” results show strong agreement with experimental data, the maximum error is only ~6.55% for Longmaxi Shale-I and ~7.50% for Jixi Coal, and the simulated failure patterns of the Longmaxi Shale-I are also consistent with the test results. For the Longmaxi Shale-I, the Brazilian disc experiences tensile failure of the intact rock when 0° ≤ βw ≤ 24°, shear failure along the weakness planes when 24° ≤ βw ≤ 76°, and tensile failure along the weakness planes when 76° ≤ βw ≤ 90°. For the Jixi Coal, the Brazilian disc experiences tensile failure when 0° ≤ βw ≤ 23° or 76° ≤ βw ≤ 90°, shear failure along the butt cleats when 23° ≤ βw ≤ 32°, and shear failure along the face cleats when 32° ≤ βw ≤ 76°. The proposed method can not only be used to predict the “BtS” and underpin the failure mechanisms of anisotropic rocks containing a single group of weakness planes, but can also be generalized for fractured rocks containing multi-groups of weakness planes.

  5. Influence of copper foil polycrystalline structure on graphene anisotropic etching

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Kamal P. [Department of Frontier Materials, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Mahyavanshi, Rakesh D. [Department of Physical Science and Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Kalita, Golap, E-mail: kalita.golap@nitech.ac.jp [Department of Frontier Materials, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Department of Physical Science and Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Tanemura, Masaki [Department of Frontier Materials, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Department of Physical Science and Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan)

    2017-01-30

    Graphical abstract: Hexagonal hole formation with anisotropic etching independent of the stripes and wrinkles in the synthesized graphene. We also observed variation in etched pattern of the graphene depending on the base Cu grain orientations, attributing to difference in nucleation and growth process. - Highlights: • Reveal the influence of copper polycrystalline structure on anisotropic etching of graphene. • Hexagonal hole formation with etching is observed to be independent of stripes and wrinkles in graphene. • Variation in etched pattern of graphene depending on the base Cu grain is confirmed. • This finding will help to understand the nature of microscopic etched pattern in graphene. - Abstract: Anisotropic etching of graphene and other two dimensional materials is an important tool to understand the growth process as well as enabling fabrication of various well-defined structures. Here, we reveal the influence of copper foil polycrystalline structure on anisotropic etching process of as-synthesized graphene. Graphene crystals were synthesized on the polycrystalline Cu foil by a low-pressure chemical vapor deposition (LPCVD) system. Microscopic analysis shows difference in shape, size and stripes alignment of graphene crystals with dissimilar nucleation within closure vicinity of neighboring Cu grains. Post-growth etching of such graphene crystals also significantly affected by the crystallographic nature of Cu grains as observed by the field emission scanning electron microscope (FE-SEM) and electron back scattered diffraction (EBSD) analysis. Hexagonal hole formation with anisotropic etching is observed to be independent of the stripes and wrinkles in the synthesized graphene. We also observed variation in etched pattern of the graphene depending on the base Cu grain orientations, attributing to difference in nucleation and growth process. The findings can facilitate to understand the nature of microscopic etched pattern depending on metal

  6. Anisotropic Hall effect in single domain YBaCuO superconductor in mixed state

    Czech Academy of Sciences Publication Activity Database

    Janeček, Ivan; Vašek, Petr

    2008-01-01

    Roč. 468, č. 1 (2008), s. 17-22 ISSN 0921-4534 R&D Projects: GA ČR GA203/05/0114 Institutional research plan: CEZ:AV0Z10100521 Keywords : superconductor * transport properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.740, year: 2008

  7. Mixed segmentation

    DEFF Research Database (Denmark)

    Hansen, Allan Grutt; Bonde, Anders; Aagaard, Morten

    This book is about using recent developments in the fields of data analytics and data visualization to frame new ways of identifying target groups in media communication. Based on a mixed-methods approach, the authors combine psychophysiological monitoring (galvanic skin response) with textual...... content analysis and audience segmentation in a single-source perspective. The aim is to explain and understand target groups in relation to, on the one hand, emotional response to commercials or other forms of audio-visual communication and, on the other hand, living preferences and personality traits...

  8. Isospin Mixing In N $\\approx$ Z Nuclei

    CERN Multimedia

    Srnka, D; Versyck, S; Zakoucky, D

    2002-01-01

    Isospin mixing in N $\\approx$ Z nuclei region of the nuclear chart is an important phenomenon in nuclear physics which has recently gained theoretical and experimental interest. It also forms an important nuclear physics correction in the precise determination of the $ft$-values of superallowed 0$^+ \\rightarrow 0^+ \\beta$- transitions. The latter are used in precision tests of the weak interaction from nuclear $\\beta$- decay. We propose to experimentally measure isospin mixing into nuclear ground states in the N $\\approx$ Z region by determining the isospin forbidden Fermi-component in the Gamow-Teller dominated $J^{\\pi} \\rightarrow J^{\\pi} \\beta$- transitions through the observation of anisotropic positron emission from oriented nuclei. First measurements were carried out with $^{71}$As and are being analyzed now.

  9. Subsurface Flow Modeling in Single and Dual Continuum Anisotropic Porous Media using the Multipoint Flux Approximation Method

    KAUST Repository

    Negara, Ardiansyah

    2015-05-01

    phases, migrates upwards and the anisotropy aligns the flow directions closer to the principal direction of anisotropy. Lastly, for the gas flow modeling in anisotropic shale reservoirs, we observe that anisotropy affects the pressure fields and the velocity fields of the matrix and fracture systems as well as the production rate and cumulative production. It is observed from the results that all of the anisotropic cases produce higher amount of gas compared to isotropic case during the same production time. Furthermore, we have also examined the performance of MPFA with respect to mixed finite element (MFE) method over the lowest-order Raviart-Thomas (RT0) space and the first-order Brezzi-Douglas-Marini (BDM1) space. From the comparison of the numerical results we observe that MPFA method show very good agreement with the BDM1 than RT0. In terms of numerical implementation, however, MPFA method is easier than BDM1 and it also offers explicit discrete fluxes that are advantageous. Combining MPFA with the experimenting pressure field approach will certainly adds another advantage of implementing MPFA method as compared with RT0 and BDM1. Moreover, the computational cost (CPU cost) of the three different methods are also discussed.

  10. Quantitative multi-waves migration in elastic anisotropic media; Migration quantitative multi-ondes en milieu elastique anisotrope

    Energy Technology Data Exchange (ETDEWEB)

    Borgne, H.

    2004-12-01

    Seismic imaging is an important tool for ail exploration. From the filtered seismic traces and a subsurface velocity model, migration allows to localize the reflectors and to estimate physical properties of these interfaces. The subsurface is split up into a reference medium, corresponding to the low spatial frequencies (a smooth medium), and a perturbation medium, corresponding to the high spatial frequencies. The propagation of elastic waves in the medium of reference is modelled by the ray theory. The association of this theory with a principle of diffraction or reflection allows to take into account the high spatial frequencies: the Kirchhoff approach represents so the medium of perturbations with continuous surfaces, characterized by reflection coefficients. The target of the quantitative migration is to reconstruct this reflection coefficient, notably its behaviour according to the incidence angle. These information will open the way to seismic characterization of the reservoir domain, with. a stratigraphic inversion for instance. In order to improve the qualitative and quantitative migration results, one of the current challenges is to take into account the anisotropy of the subsurface. Taking into account rocks anisotropy in the imaging process of seismic data requires two improvements from the isotropic case. The first one roughly concerns the modelling aspect: an anisotropic propagator should be used to avoid a mis-positioning or bad focusing of the imaged reflectors. The second correction concerns the migration aspect: as anisotropy affects the reflectivity of subsurface, a specific anisotropic imaging formula should be applied in the migration kernel, in order to recover the correct A V A behavior of the subsurface reflectors, If the first correction is DOW made in most so-called anisotropic imaging algorithms, the second one is currently ignored. The first part of my work concerns theoretical aspects. 1 study first the preservation of amplitudes in the

  11. Nanoscale Rheology and Anisotropic Diffusion Using Single Gold Nanorod Probes

    Science.gov (United States)

    Molaei, Mehdi; Atefi, Ehsan; Crocker, John C.

    2018-03-01

    The complex rotational and translational Brownian motion of anisotropic particles depends on their shape and the viscoelasticity of their surroundings. Because of their strong optical scattering and chemical versatility, gold nanorods would seem to provide the ultimate probes of rheology at the nanoscale, but the suitably accurate orientational tracking required to compute rheology has not been demonstrated. Here we image single gold nanorods with a laser-illuminated dark-field microscope and use optical polarization to determine their three-dimensional orientation to better than one degree. We convert the rotational diffusion of single nanorods in viscoelastic polyethylene glycol solutions to rheology and obtain excellent agreement with bulk measurements. Extensions of earlier models of anisotropic translational diffusion to three dimensions and viscoelastic fluids give excellent agreement with the observed motion of single nanorods. We find that nanorod tracking provides a uniquely capable approach to microrheology and provides a powerful tool for probing nanoscale dynamics and structure in a range of soft materials.

  12. Optical characterization of isotropic and anisotropic layered media

    CERN Document Server

    Jakopic, G

    2000-01-01

    This work deals with the interaction of electromagnetic radiation in the UV/IR region with layered media and the inversion of photometric and ellipsometric spectra. A method is presented how to calculate the dielectric function of an ensemble of different anisotropic oscillators. A way is proposed how to extract both components of the dielectric tensor of uniaxial oligomers out of spectroscopic measurements at normal incidence, if it is possible to make two different structural modifications of the oligomer. Then, effective medium theories with an expansion on anisotropic media are treated and the result is used to model the optical properties of the rough surface of an organic thin film. Further, a new unified analytical inversion of reflectometric and ellipsometric data of strongly absorbing media is presented. A method is shown how to calculate simultaneously the thickness and the optical constants of weakly absorbing films out of one spectroscopic reflection or transmission measurement. The last topic are...

  13. A resistor interpretation of general anisotropic cardiac tissue.

    Science.gov (United States)

    Shao, Hai; Sampson, Kevin J; Pormann, John B; Rose, Donald J; Henriquez, Craig S

    2004-02-01

    This paper describes a spatial discretization scheme for partial differential equation systems that contain anisotropic diffusion. The discretization method uses unstructured finite volumes, or the boxes, that are formed as a secondary geometric structure from an underlying triangular mesh. We show how the discretization can be interpreted as a resistive circuit network, where each resistor is assigned at each edge of the triangular element. The resistor is computed as an anisotropy dependent geometric quantity of the local mesh structure. Finally, we show that under certain conditions, the discretization gives rise to negative resistors that can produce non-physical hyperpolarizations near depolarizing stimuli. We discuss how the proper choice of triangulation (anisotropic Delaunay triangulation) can ensure monotonicity (i.e. all resistors are positive).

  14. Anisotropic hypersonic phonon propagation in films of aligned ellipsoids.

    Science.gov (United States)

    Beltramo, Peter J; Schneider, Dirk; Fytas, George; Furst, Eric M

    2014-11-14

    A material with anisotropic elastic mechanical properties and a direction-dependent hypersonic band gap is fabricated using ac electric field-directed convective self-assembly of colloidal ellipsoids. The frequency of the gap, which is detected in the direction perpendicular to particle alignment and entirely absent parallel to alignment, and the effective sound velocities can be tuned by the particle aspect ratio. We hypothesize that the band gap originates from the primary eigenmode peak, the m-splitted (s,1,2) mode, of the particle resonating with the effective medium. These results reveal the potential for powerful control of the hypersonic phononic band diagram by combining anisotropic particles and self-assembly.

  15. Coupled polaritonic band gaps in the anisotropic piezoelectric superlattices

    Science.gov (United States)

    Tang, Zheng-Hua; Jiang, Zheng-Sheng; Chen, Tao; Jiang, Chun-Zhi; Lei, Da-Jun; Huang, Jian-Quan; Qiu, Feng; Yao, Min; Huang, Xiao-Yi

    2018-01-01

    Anisotropic piezoelectric superlattices (APSs) with the periodic arrangement of polarized anisotropic piezoelectric domains in a certain direction are presented, in which the coupled polaritonic band gaps (CPBGs) can be obtained in the whole Brillouin Zone and the maximum relative bandwidth (band-gap sizes divided by their midgap frequencies) of 5.1% can be achieved. The general characteristics of the APSs are similar to those of the phononic crystals composed of two types of materials, with the main difference being the formation mechanism of the CPBGs, which originate from the couplings between lattice vibrations along two different directions and electromagnetic waves rather than from the periodical modulation of density and elastic constants. In addition, there are no lattice mismatches because the APSs are made of the same material. Thus, the APSs can also be extended to the construction of novel acousto-optic devices.

  16. Anisotropic mechanical properties of graphene sheets from molecular dynamics

    International Nuclear Information System (INIS)

    Ni Zhonghua; Bu Hao; Zou Min; Yi Hong; Bi Kedong; Chen Yunfei

    2010-01-01

    Anisotropic mechanical properties are observed for a sheet of graphene along different load directions. The anisotropic mechanical properties are attributed to the hexagonal structure of the unit cells of the graphene. Under the same tensile loads, the edge bonds bear larger load in the longitudinal mode (LM) than in the transverse mode (TM), which causes fracture sooner in LM than in TM. The Young's modulus and the third order elastic modulus for the LM are slightly larger than that for the TM. Simulation also demonstrates that, for both LM and TM, the loading and unloading stress-strain response curves overlap as long as the graphene is unloaded before the fracture point. This confirms that graphene sustains complete elastic and reversible deformation in the elongation process.

  17. Local deposition of anisotropic nanoparticles using scanning electrochemical microscopy (SECM).

    Science.gov (United States)

    Fedorov, Roman G; Mandler, Daniel

    2013-02-28

    We demonstrate localized electrodeposition of anisotropic metal nanoobjects, namely Au nanorods (GNR), on indium tin oxide (ITO) using scanning electrochemical microscopy (SECM). A gold microelectrode was the source of the gold ions whereby double pulse chronoamperometry was employed to generate initially Au seeds which were further grown under controlled conditions. The distance between the microelectrode and the ITO surface as well as the different experimental parameters (electrodeposition regime, solution composition and temperature) were optimized to produce faceted gold seeds with the required characteristics (size and distribution). Colloidal chemical synthesis was successfully exploited for better understanding the role of the surfactant and different additives in breaking the crystallographic symmetry and anisotropic growth of GNR. Experiments performed in a conventional three-electrode cell revealed the most appropriate electrochemical conditions allowing high yield synthesis of nanorods with well-defined shape as well as nanocubes and bipyramids.

  18. Synthesis of borophenes: Anisotropic, two-dimensional boron polymorphs.

    Science.gov (United States)

    Mannix, Andrew J; Zhou, Xiang-Feng; Kiraly, Brian; Wood, Joshua D; Alducin, Diego; Myers, Benjamin D; Liu, Xiaolong; Fisher, Brandon L; Santiago, Ulises; Guest, Jeffrey R; Yacaman, Miguel Jose; Ponce, Arturo; Oganov, Artem R; Hersam, Mark C; Guisinger, Nathan P

    2015-12-18

    At the atomic-cluster scale, pure boron is markedly similar to carbon, forming simple planar molecules and cage-like fullerenes. Theoretical studies predict that two-dimensional (2D) boron sheets will adopt an atomic configuration similar to that of boron atomic clusters. We synthesized atomically thin, crystalline 2D boron sheets (i.e., borophene) on silver surfaces under ultrahigh-vacuum conditions. Atomic-scale characterization, supported by theoretical calculations, revealed structures reminiscent of fused boron clusters with multiple scales of anisotropic, out-of-plane buckling. Unlike bulk boron allotropes, borophene shows metallic characteristics that are consistent with predictions of a highly anisotropic, 2D metal. Copyright © 2015, American Association for the Advancement of Science.

  19. Anisotropic plasmons, excitons, and electron energy loss spectroscopy of phosphorene

    Science.gov (United States)

    Ghosh, Barun; Kumar, Piyush; Thakur, Anmol; Chauhan, Yogesh Singh; Bhowmick, Somnath; Agarwal, Amit

    2017-07-01

    In this article, we explore the anisotropic electron energy loss spectrum (EELS) in monolayer phosphorene based on ab initio time-dependent density-functional-theory calculations. Similarly to black phosphorus, the EELS of undoped monolayer phosphorene is characterized by anisotropic excitonic peaks for energies in the vicinity of the band gap and by interband plasmon peaks for higher energies. On doping, an additional intraband plasmon peak also appears for energies within the band gap. Similarly to other two-dimensional systems, the intraband plasmon peak disperses as ωpl∝√{q } in both the zigzag and armchair directions in the long-wavelength limit and deviates for larger wave vectors. The anisotropy of the long-wavelength plasmon intraband dispersion is found to be inversely proportional to the square root of the ratio of the effective masses: ωpl(q y ̂) /ωpl(q x ̂) =√{mx/my } .

  20. Interactions, strings and isotopies in higher order anisotropic superspaces

    CERN Document Server

    Vacaru, Sergiu Ion

    2001-01-01

    The monograph summarizes the author's results on the geometry of anholonomic and locally anisotropic interactions, published in J. Math. Phys., Nucl. Phys. B, Ann. Phys. (NY), JHEP, Rep. Math. Phys., Int. J. Theor. Phys. and in some former Soviet Union and Romanian scientific journals. The main subjects are in the theory of field interactions, strings and diffusion processes on spaces, superspaces and isospaces with higher order anisotropy and inhomogeneity. The approach proceeds by developing the concept of higher order anisotropic (super)space which unifies the logical and manthematical aspects of modern Kaluza--Klein theories and generalized Lagrange and Finsler geometry and leads to modeling of physical processes on higher order fiber (super)bundles provided with nonlinear and distinguished connections and metric structures. This book can be also considered as a pedagogical survey on the mentioned subjects.

  1. Timoshenko beam element with anisotropic cross-sectional properties

    DEFF Research Database (Denmark)

    Stäblein, Alexander; Hansen, Morten Hartvig

    2016-01-01

    Beam models are used for the aeroelastic time and frequency domain analysis of wind turbines due to their computational efficiency. Many current aeroelastic tools for the analysis of wind turbines rely on Timoshenko beam elements with classical crosssectional properties (EA, EI, etc.). Those cross......-sectional properties do not reflect the various couplings arising from the anisotropic behaviour of the blade material. A twonoded, three-dimensional Timoshenko beam element was therefore extended to allow for anisotropic cross-sectional properties. For an uncoupled beam, the resulting shape functions are identical...... to the original formulation. The new element was implemented into a co-rotational formulation and validated against natural frequencies and several static load cases of previous works....

  2. Anisotropic Friction of Wrinkled Graphene Grown by Chemical Vapor Deposition.

    Science.gov (United States)

    Long, Fei; Yasaei, Poya; Yao, Wentao; Salehi-Khojin, Amin; Shahbazian-Yassar, Reza

    2017-06-21

    Wrinkle structures are commonly seen on graphene grown by the chemical vapor deposition (CVD) method due to the different thermal expansion coefficient between graphene and its substrate. Despite the intensive investigations focusing on the electrical properties, the nanotribological properties of wrinkles and the influence of wrinkle structures on the wrinkle-free graphene remain less understood. Here, we report the observation of anisotropic nanoscale frictional characteristics depending on the orientation of wrinkles in CVD-grown graphene. Using friction force microscopy, we found that the coefficient of friction perpendicular to the wrinkle direction was ∼194% compare to that of the parallel direction. Our systematic investigation shows that the ripples and "puckering" mechanism, which dominates the friction of exfoliated graphene, plays even a more significant role in the friction of wrinkled graphene grown by CVD. The anisotropic friction of wrinkled graphene suggests a new way to tune the graphene friction property by nano/microstructure engineering such as introducing wrinkles.

  3. Driven Anisotropic Diffusion at Boundaries: Noise Rectification and Particle Sorting

    Science.gov (United States)

    Bo, Stefano; Eichhorn, Ralf

    2017-08-01

    We study the diffusive dynamics of a Brownian particle in the proximity of a flat surface under nonequilibrium conditions, which are created by an anisotropic thermal environment with different temperatures being active along distinct spatial directions. By presenting the exact time-dependent solution of the Fokker-Planck equation for this problem, we demonstrate that the interplay between anisotropic diffusion and hard-core interaction with the plain wall rectifies the thermal fluctuations and induces directed particle transport parallel to the surface, without any deterministic forces being applied in that direction. Based on current micromanipulation technologies, we suggest a concrete experimental setup to observe this novel noise-induced transport mechanism. We furthermore show that it is sensitive to particle characteristics, such that this setup can be used for sorting particles of different sizes.

  4. Dynamics of anisotropic power-law f( R) cosmology

    Science.gov (United States)

    Shamir, M. F.

    2016-12-01

    Modified theories of gravity have attracted much attention of the researchers in the recent years. In particular, the f( R) theory has been investigated extensively due to important f( R) gravity models in cosmological contexts. This paper is devoted to exploring an anisotropic universe in metric f( R) gravity. A locally rotationally symmetric Bianchi type I cosmological model is considered for this purpose. Exact solutions of modified field equations are obtained for a well-known f( R) gravity model. The energy conditions are also discussed for the model under consideration. The viability of the model is investigated via graphical analysis using the present-day values of cosmological parameters. The model satisfies null energy, weak energy, and dominant energy conditions for a particular range of the anisotropy parameter while the strong energy condition is violated, which shows that the anisotropic universe in f( R) gravity supports the crucial issue of accelerated expansion of the universe.

  5. Dirac directional emission in anisotropic zero refractive index photonic crystals.

    Science.gov (United States)

    He, Xin-Tao; Zhong, Yao-Nan; Zhou, You; Zhong, Zhi-Chao; Dong, Jian-Wen

    2015-08-14

    A certain class of photonic crystals with conical dispersion is known to behave as isotropic zero-refractive-index medium. However, the discrete building blocks in such photonic crystals are limited to construct multidirectional devices, even for high-symmetric photonic crystals. Here, we show multidirectional emission from low-symmetric photonic crystals with semi-Dirac dispersion at the zone center. We demonstrate that such low-symmetric photonic crystal can be considered as an effective anisotropic zero-refractive-index medium, as long as there is only one propagation mode near Dirac frequency. Four kinds of Dirac multidirectional emitters are achieved with the channel numbers of five, seven, eleven, and thirteen, respectively. Spatial power combination for such kind of Dirac directional emitter is also verified even when multiple sources are randomly placed in the anisotropic zero-refractive-index photonic crystal.

  6. Theoretical Investigation of Anisotropic Damping in Exchange Bias Systems

    Science.gov (United States)

    Farrar, Alison; Beik Mohammadi, Jamileh; Mewes, Tim; Mewes, Claudia

    An accurate description of the magnetization dynamics of exchange bias systems is essential for further development of computer read heads and STT-MRAM. There have been several theoretical predictions of an anisotropic Gilbert damping tensor, influenced by the symmetry of the crystal structure, in place of the scalar Gilbert damping parameter in the Landau-Lifshitz-Gilbert equation of motion. However, experimental confirmation is difficult as the anisotropy of the damping parameter is expected to be small for single crystals. We follow up on our experimental discovery of a strong unidirectional contribution to the relaxation of exchange bias systems by implementing an anisotropic damping tensor in our Matlab-based micromagnetics code M3. We present results for a damping tensor with unidirectional anisotropy with respect to the instantaneous orientation of the magnetization. NSF-CAREER No 1452670 and 0952929, UA Computer-Based Honors Program.

  7. Ultraviolet laser-induced voltage in anisotropic shale

    Science.gov (United States)

    Miao, Xinyang; Zhu, Jing; Li, Yizhang; Zhao, Kun; Zhan, Honglei; Yue, Wenzheng

    2018-01-01

    The anisotropy of shales plays a significant role in oil and gas exploration and engineering. Owing to various problems and limitations, anisotropic properties were seldom investigated by direct current resistivity methods. Here in this work, a 248 nm ultraviolet laser was employed to assess the anisotropic electrical response of a dielectric shale. Angular dependence of laser-induced voltages (V p) were obtained, with a data symmetry at the location of 180° and a ~62.2% V p anisotropy of the sample. The double-exponential functions have provided an explanation for the electrical field controlled carrier transportation process in horizontal and vertical directions. The results demonstrate that the combination of optics and electrical logging analysis (Opti-electrical Logging) is a promising technology for the investigation of unconventional reservoirs.

  8. Static anisotropic solutions in f(T) theory

    Energy Technology Data Exchange (ETDEWEB)

    Daouda, M.H.; Rodrigues, Manuel E. [Universidade Federal do Espirito Santo, Centro de Ciencias Exatas, Departamento de Fisica, Av. Fernando Ferrari s/n, Campus de Goiabeiras, CEP29075-910, Vitoria, ES (Brazil); Houndjo, M.J.S. [Universidade Federal da Bahia, Instituto de Fisica, Salvador, BA (Brazil)

    2012-02-15

    In previous work, we undertook to study static and anisotropic content in f(T) theory and obtained new spherically symmetric solutions considering a constant torsion and some particular conditions for the pressure. In this paper, still in the framework of f(T) theory, new spherically symmetric solutions are obtained, first considering the general case of an isotropic fluid and later the anisotropic content case in which the generalized conditions for the matter content are considered such that the energy density, the radial and tangential pressures depend on the algebraic f(T) and its derivative f{sub T} (T). Moreover, we obtain the algebraic function f(T) through the reconstruction method for two cases and also study a polytropic model for the stellar structure. (orig.)

  9. Newton–Hooke-type symmetry of anisotropic oscillators

    International Nuclear Information System (INIS)

    Zhang, P.M.; Horvathy, P.A.; Andrzejewski, K.; Gonera, J.; Kosiński, P.

    2013-01-01

    Rotation-less Newton–Hooke-type symmetry, found recently in the Hill problem, and instrumental for explaining the center-of-mass decomposition, is generalized to an arbitrary anisotropic oscillator in the plane. Conversely, the latter system is shown, by the orbit method, to be the most general one with such a symmetry. Full Newton–Hooke symmetry is recovered in the isotropic case. Star escape from a galaxy is studied as an application. -- Highlights: ► Rotation-less Newton–Hooke (NH) symmetry is generalized to an arbitrary anisotropic oscillator. ► The orbit method is used to find the most general case for rotation-less NH symmetry. ► The NH symmetry is decomposed into Heisenberg algebras based on chiral decomposition

  10. An anisotropic diffusion approximation to thermal radiative transfer

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Seth R.; Larsen, Edward W., E-mail: sethrj@umich.edu, E-mail: edlarsen@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI (United States)

    2011-07-01

    This paper describes an anisotropic diffusion (AD) method that uses transport-calculated AD coefficients to efficiently and accurately solve the thermal radiative transfer (TRT) equations. By assuming weak gradients and angular moments in the radiation intensity, we derive an expression for the radiation energy density that depends on a non-local function of the opacity. This nonlocal function is the solution of a transport equation that can be solved with a single steady-state transport sweep once per time step, and the function's second angular moment is the anisotropic diffusion tensor. To demonstrate the AD method's efficacy, we model radiation flow down a channel in 'flatland' geometry. (author)

  11. The boundary sources method with arbitrary order anisotropic scattering

    International Nuclear Information System (INIS)

    Gert Van den, Eynde; Beauwens, R.; Mund, E.

    2005-01-01

    The Boundary Sources Method (BSM) is an integral method for solving the one-speed neutron transport equation that makes capital out of the exact knowledge of a transport kernel for the classical geometries: planar, spherical and cylindrical. We have developed a slab (multi-region) BSM code that allows for arbitrary order anisotropic scattering. The basic ingredient of our method is the calculation of (angular moments of) infinite medium Green's functions. We have used the singular Eigen-expansion (SEE) method developed for anisotropic scattering by Mika and Case and have developed a robust and accurate method to calculate its two parts: the discrete and continuum spectrum. We use several one-dimensional neutron transport benchmarks to show its high accuracy. We have treated 3 types of problems: 2-cell (U-H 2 O) disadvantage factors, the Reed problem and an extreme scattering problem

  12. Statistical ensembles and molecular dynamics studies of anisotropic solids. II

    International Nuclear Information System (INIS)

    Ray, J.R.; Rahman, A.

    1985-01-01

    We have recently discussed how the Parrinello--Rahman theory can be brought into accord with the theory of the elastic and thermodynamic behavior of anisotropic media. This involves the isoenthalpic--isotension ensemble of statistical mechanics. Nose has developed a canonical ensemble form of molecular dynamics. We combine Nose's ideas with the Parrinello--Rahman theory to obtain a canonical form of molecular dynamics appropriate to the study of anisotropic media subjected to arbitrary external stress. We employ this isothermal--isotension ensemble in a study of a fcc→ close-packed structural phase transformation in a Lennard-Jones solid subjected to uniaxial compression. Our interpretation of the Nose theory does not involve a scaling of the time variable. This latter fact leads to simplifications when studying the time dependence of quantities

  13. Anisotropic models are unitary: A rejuvenation of standard quantum cosmology

    Science.gov (United States)

    Pal, Sridip; Banerjee, Narayan

    2016-12-01

    The present work proves that the folklore of the pathology of non-conservation of probability in quantum anisotropic models is wrong. It is shown in full generality that all operator ordering can lead to a Hamiltonian with a self-adjoint extension as long as it is constructed as a symmetric operator. It is indicated that the self-adjoint extension, however, is not unique and this non-uniqueness is suspected not to be a feature of anisotropic models only, in the sense that there exists operator orderings such that Hamiltonian for an isotropic homogeneous cosmological model does not have unique self-adjoint extension. For isotropic model, there is a special unique extension associated with quadratic form of Hamiltonian, i.e., a Friedrich's extension. Details of calculations are carried out for a Bianchi III model as an example.

  14. Anisotropic charged physical models with generalized polytropic equation of state

    Science.gov (United States)

    Nasim, A.; Azam, M.

    2018-01-01

    In this paper, we found the exact solutions of Einstein-Maxwell equations with generalized polytropic equation of state (GPEoS). For this, we consider spherically symmetric object with charged anisotropic matter distribution. We rewrite the field equations into simple form through transformation introduced by Durgapal (Phys Rev D 27:328, 1983) and solve these equations analytically. For the physically acceptability of these solutions, we plot physical quantities like energy density, anisotropy, speed of sound, tangential and radial pressure. We found that all solutions fulfill the required physical conditions. It is concluded that all our results are reduced to the case of anisotropic charged matter distribution with linear, quadratic as well as polytropic equation of state.

  15. Ballistic Anisotropic Magnetoresistance of Single-Atom Contacts.

    Science.gov (United States)

    Schöneberg, J; Otte, F; Néel, N; Weismann, A; Mokrousov, Y; Kröger, J; Berndt, R; Heinze, S

    2016-02-10

    Anisotropic magnetoresistance, that is, the sensitivity of the electrical resistance of magnetic materials on the magnetization direction, is expected to be strongly enhanced in ballistic transport through nanoscale junctions. However, unambiguous experimental evidence of this effect is difficult to achieve. We utilize single-atom junctions to measure this ballistic anisotropic magnetoresistance (AMR). Single Co and Ir atoms are deposited on domains and domain walls of ferromagnetic Fe layers on W(110) to control their magnetization directions. They are contacted with nonmagnetic tips in a low-temperature scanning tunneling microscope to measure the junction conductances. Large changes of the magnetoresistance occur from the tunneling to the ballistic regime due to the competition of localized and delocalized d-orbitals, which are differently affected by spin-orbit coupling. This work shows that engineering the AMR at the single atom level is feasible.

  16. Anisotropic to Isotropic Phase Transitions in the Early Universe

    Directory of Open Access Journals (Sweden)

    Ajaib M. A.

    2012-04-01

    Full Text Available We attempt to develop a minimal formalism to describe an anisotropic to isotropic tran- sition in the early Universe. Assuming an underlying theory that violates Lorentz in- variance, we start with a Dirac like equation, involving four massless fields, and which does not exhibit Lorentz invariance. We then perform transformations that restore it to its covariant form along with a mass term for the fermion field. It is proposed that these transformations can be visualized as waves traveling in an anisotropic media. The trans- formation it = ℏ ! is then utilized to transit to a statistical thermodynamics system and the partition function then gives a better insight into the character of this transition. The statistical system hence realized is a two level system with each state doubly degenerate. We propose that modeling the transition this way can help explain the matter antimatter asymmetry of the Universe.

  17. Holographic Fermions in Anisotropic Einstein-Maxwell-Dilaton-Axion Theory

    Directory of Open Access Journals (Sweden)

    Li-Qing Fang

    2015-01-01

    Full Text Available We investigate the properties of the holographic Fermionic system dual to an anisotropic charged black brane bulk in Einstein-Maxwell-Dilaton-Axion gravity theory. We consider the minimal coupling between the Dirac field and the gauge field in the bulk gravity theory and mainly explore the dispersion relation exponents of the Green functions of the dual Fermionic operators in the dual field theory. We find that along both the anisotropic and the isotropic directions the Fermi momentum will be effected by the anisotropy of the bulk theory. However, the anisotropy has influence on the dispersion relation which is almost linear for massless Fermions with charge q=2. The universal properties that the mass and the charge of the Fermi possibly correspond to nonlinear dispersion relation are also investigated.

  18. Life prediction and constitutive models for anisotropic materials

    Science.gov (United States)

    Bill, R. C.

    1982-01-01

    The intent of this program is to develop a basic understanding of cyclic creep-fatigue deformation mechanisms and damage accumulation, a capability for reliable life prediction, and the ability to model the constitutive behavior of anisotropic single crystal (SC) and directionally solidified or recrystallized (DSR) comprise the program, and the work breakdown for each option reflects a distinct concern for two classes of anisotropic materials, SC and DSR materials, at temperatures encountered in the primary gas path (airfoil temperatures), and at temperatures typical of the blade root attachment and shank area. Work directed toward the higher temperature area of concern in the primary gas path includes effects of coatings on the behavior and properties of the materials of interest. The blade root attachment work areas will address the effects of stress concentrations associated with attachment features.

  19. Theory for propulsion and transport in an anisotropic fluid

    Science.gov (United States)

    Powers, Thomas; Krieger, Madison; Spagnolie, Saverio

    2013-11-01

    Swimming microorganisms are typically found in complex fluids, which are full of polymers. When these polymers align, the fluid becomes anisotropic. We seek to understand how anisotropy affects swimming when the stroke is prescribed. We model the anisotropic fluid with a nematic liquid crystal. The swimmer is a two-dimensional sheet deforming via propagating transverse or longitudinal waves. We find that the nature of anchoring conditions for the nematic degrees of freedom plays a critical role in determining the swimming speed. Furthermore, we study the fluid transport induced by the swimmers motion by calculating the flux of fluid in the laboratory frame. Finally, we elucidate the various limits of the nematic theory, such as the six-fold symmetric hexatic case and Ericksen's transversely isotropic fluid.

  20. Mixed cryoglobulinemia

    Directory of Open Access Journals (Sweden)

    Ferri Clodoveo

    2008-09-01

    Full Text Available Abstract Mixed cryoglobulinemia (MC, type II and type III, refers to the presence of circulating cryoprecipitable immune complexes in the serum and manifests clinically by a classical triad of purpura, weakness and arthralgias. It is considered to be a rare disorder, but its true prevalence remains unknown. The disease is more common in Southern Europe than in Northern Europe or Northern America. The prevalence of 'essential' MC is reported as approximately 1:100,000 (with a female-to-male ratio 3:1, but this term is now used to refer to a minority of MC patients only. MC is characterized by variable organ involvement including skin lesions (orthostatic purpura, ulcers, chronic hepatitis, membranoproliferative glomerulonephritis, peripheral neuropathy, diffuse vasculitis, and, less frequently, interstitial lung involvement and endocrine disorders. Some patients may develop lymphatic and hepatic malignancies, usually as a late complication. MC may be associated with numerous infectious or immunological diseases. When isolated, MC may represent a distinct disease, the so-called 'essential' MC. The etiopathogenesis of MC is not completely understood. Hepatitis C virus (HCV infection is suggested to play a causative role, with the contribution of genetic and/or environmental factors. Moreover, MC may be associated with other infectious agents or immunological disorders, such as human immunodeficiency virus (HIV infection or primary Sjögren's syndrome. Diagnosis is based on clinical and laboratory findings. Circulating mixed cryoglobulins, low C4 levels and orthostatic skin purpura are the hallmarks of the disease. Leukocytoclastic vasculitis involving medium- and, more often, small-sized blood vessels is the typical pathological finding, easily detectable by means of skin biopsy of recent vasculitic lesions. Differential diagnoses include a wide range of systemic, infectious and neoplastic disorders, mainly autoimmune hepatitis, Sjögren's syndrome

  1. Pseudorapidity Dependence of Anisotropic Azimuthal Flow with the ALICE Detector

    DEFF Research Database (Denmark)

    Hansen, Alexander Colliander

    In ultra-relativistic heavy-ion collisions a new state of matter known as the strongly interacting quark-gluon plasma (sQGP) is produced. A key observable in the study of the sQGP is anisotropic azimuthal ow. The anisotropies are described by ow harmonics, vn. In this thesis, bias arising from no...... Detector and Silicon Pixel Detector at the CERN Large Hadron Collider (LHC). The results are compared to other LHC experiments andprevious experiments at lower collision energies....

  2. Wave propagation in layered anisotropic media with application to composites

    CERN Document Server

    Nayfeh, AH

    1995-01-01

    Recent advances in the study of the dynamic behavior of layered materials in general, and laminated fibrous composites in particular, are presented in this book. The need to understand the microstructural behavior of such classes of materials has brought a new challenge to existing analytical tools. This book explores the fundamental question of how mechanical waves propagate and interact with layered anisotropic media. The chapters are organized in a logical sequence depending upon the complexity of the physical model and its mathematical treatment.

  3. The second critical density and anisotropic generalised condensation

    Directory of Open Access Journals (Sweden)

    M. Beau

    2010-01-01

    Full Text Available In this letter we discuss the relevance of the 3D Perfect Bose gas (PBG condensation in extremely elongated vessels for the study of anisotropic condensate coherence and the "quasi-condensate". To this end we analyze the case of exponentially anisotropic (van den Berg boxes, when there are two critical densities ρc<ρm for a generalised Bose-Einstein Condensation (BEC. Here ρc is the standard critical density for the PBG. We consider three examples of anisotropic geometry: slabs, squared beams and "cigars" to demonstrate that the "quasi-condensate" which exists in domain ρc<ρ<ρm is in fact the van den Berg-Lewis-Pulé generalised condensation (vdBLP-GC of the type III with no macroscopic occupation of any mode. We show that for the slab geometry the second critical density ρm is a threshold between quasi-two-dimensional (quasi-2D condensate and the three dimensional (3D regime when there is a coexistence of the "quasi-condensate" with the standard one-mode BEC. On the other hand, in the case of squared beams and "cigars" geometries, critical density ρm separates quasi-1D and 3D regimes. We calculate the value of the difference between ρc, ρm (and between corresponding critical temperatures Tm, Tc to show that the observed space anisotropy of the condensate coherence can be described by a critical exponent γ(T related to the anisotropic ODLRO. We compare our calculations with physical results for extremely elongated traps that manifest "quasi-condensate".

  4. Theoretical assessment of sound absorption coefficient for anisotropic nonwovens

    OpenAIRE

    Klara Kalinova

    2012-01-01

    The anisotropy factor as a function of fiber arrangement, fiber fineness and sample thickness has been derived from the theories of soundwave transformation due to phase changing. The sound absorption coefficient of the anisotropic fibrous material is then theoretically calculated. The fibrous materials were prepared so that the fibers are arranged parallel (perpendicularly laid fiber web called STRUTO technology) in the direction of soundwave propagation or perpendicularly (longitudinally la...

  5. Existence of longitudinal waves in pre-stressed anisotropic elastic ...

    Indian Academy of Sciences (India)

    In the absence of pre-stresses, i.e., taking. S11 = S22 = S33 = 0, all the expressions, derived in this section, will reduce to the results which are same as in Ting (2006). 4. Triclinic materials. A triclinic material is the most general anisotropic medium, and the elastic compliance b11(N) in this medium is as defined by equation ...

  6. Anisotropic static solutions in modelling highly compact bodies

    Indian Academy of Sciences (India)

    x2µ(x)dx which is the mass function. The radial pressure pr = p + 2S/. √. 3 and the tangential pressure p⊥ = p − S/. √. 3 are not equal for anisotropic matter. The magnitude S provides a measure of anisotropy. The field equations (1)–(3) were integrated by Chaisi and Maharaj [12] for the energy density. µ = j r2. + k + lr2,. (4).

  7. Charged anisotropic star on paraboloidal space-time

    Indian Academy of Sciences (India)

    dr2 − r2 ( dθ2 + sin2 θdφ2). ,. (1) with the energy–momentum tensor for anisotropic charged fluid,. Tij = diag. ( ρ + E2, pr − E2, pt + E2, pt + E2). ,. (2) where ρ is the energy density, pr is the radial pressure, pt is the tangential pressure and. E is the electric field intensity. These quantities are measured relative to the comoving.

  8. Anisotropic shift of the irreversibility line by neutron irradiation

    International Nuclear Information System (INIS)

    Sauerzopf, F.M.; Wiesinger, H.P.; Weber, H.W.; Crabtree, G.W.; Frischherz, M.C.; Kirk, M.A.

    1991-09-01

    The irreversibility line of high-T c superconductors is shifted considerably by irradiating the material with fast neutrons. The anisotropic and non-monotonous shift is qualitatively explained by a simple model based on an interaction between three pinning mechanisms, the intrinsic pinning by the ab-planes, the weak pinning by the pre-irradiation defect structure, and strong pinning by neutron induced defect cascades. A correlation between the cascade density and the position of the irreversibility line is observed

  9. Efficient light propagation for multiple anisotropic volume scattering

    Energy Technology Data Exchange (ETDEWEB)

    Max, N. [Lawrence Livermore National Lab., CA (United States)]|[California Univ., Davis, CA (United States)

    1993-12-01

    Realistic rendering of participating media like clouds requires multiple anisotropic light scattering. This paper presents a propagation approximation for light scattered into M direction bins, which reduces the ``ray effect`` problem in the traditional ``discrete ordinates`` method. For a volume of n{sup 3} elements, it takes O(M n{sup 3} log n + M{sup 2} n{sup 3}) time and O(M n{sup 3}) space.

  10. Circumferential gap propagation in an anisotropic elastic bacterial sacculus

    OpenAIRE

    Taneja, Swadhin; Levitan, Benjamin A.; Rutenberg, Andrew D.

    2013-01-01

    We have modelled stress concentration around small gaps in anisotropic elastic sheets, corresponding to the peptidoglycan sacculus of bacterial cells, under loading corresponding to the effects of turgor pressure in rod-shaped bacteria. We find that under normal conditions the stress concentration is insufficient to mechanically rupture bacteria, even for gaps up to a micron in length. We then explored the effects of stress-dependent smart-autolysins, as hypothesised by Arthur L Koch [Advance...

  11. Model and calculation of in situ stresses in anisotropic formations

    Energy Technology Data Exchange (ETDEWEB)

    Yuezhi, W.; Zijun, L.; Lixin, H. [Jianghan Petroleum Institute, (China)

    1997-08-01

    In situ stresses in transversely isotropic material in relation to wellbore stability have been investigated. Equations for three horizontal in- situ stresses and a new formation fracture pressure model were described, and the methodology for determining the elastic parameters of anisotropic rocks in the laboratory was outlined. Results indicate significantly smaller differences between theoretically calculated pressures and actual formation pressures than results obtained by using the isotropic method. Implications for improvements in drilling efficiency were reviewed. 13 refs., 6 figs.

  12. Anisotropic square lattice Potts ferromagnet: renormalization group treatment

    International Nuclear Information System (INIS)

    Oliveira, P.M.C. de; Tsallis, C.

    1981-01-01

    The choice of a convenient self-dual cell within a real space renormalization group framework enables a satisfactory treatment of the anisotropic square lattice q-state Potts ferromagnet criticality. The exact critical frontier and dimensionality crossover exponent PHI as well as the expected universality behaviour (renormalization flow sense) are recovered for any linear scaling factor b and all values of q(q - [pt

  13. Anisotropic magnetoresistance of GaMnAs ferromagnetic semiconductors

    Czech Academy of Sciences Publication Activity Database

    Vašek, Petr; Svoboda, Pavel; Novák, Vít; Cukr, Miroslav; Výborný, Karel; Jurka, Vlastimil; Stuchlík, Jiří; Orlita, Milan; Maude, D. K.

    2010-01-01

    Roč. 23, č. 6 (2010), 1161-1163 ISSN 1557-1939 R&D Projects: GA AV ČR KAN400100652; GA MŠk MEB020928 Grant - others:EU EuroMagNET II(XE) Egide 19535NF Institutional research plan: CEZ:AV0Z10100521 Keywords : GaMnAs * anisotropic magnetoresistance * hydrogenation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.014, year: 2010

  14. LIGHT ABERRATION IN OPTICAL ANISOTROPIC SINGLE-AXIS MEDIUM

    Directory of Open Access Journals (Sweden)

    V. M. Svishch

    2017-10-01

    Full Text Available The entrainment of the light flux by a uniaxial anisotropic medium and its influence on the measurement of stellar aberration are analyzed. The influence of the entrainment of the light flux by an isotropic medium on the measurement of stellar aberration was considered by Fresnel early. The absence of such influence was confirmed by Erie's experience when filling the telescope tube with water. The formula itself was perfectly confirmed by Fizeau's experiments with moving water and the repetition of this experiment with an increase in the accuracy of measurements by Michelson, Zeeman, and others. G.A. Lorentz already on the basis of the electromagnetic theory specified the formula with allowance for the frequency dispersion of the light flux. A. Einstein made an analysis of the schemes of experiments for determining the drag coefficient, covering all possible variants of similar experiments. As a result, he obtained Fresnel and Lorentz formulas, taking into account the frequency dispersion of light, starting from the theory of relativity. The entrainment of light and its influence on the measurement of stellar aberration by a uniaxial anisotropic medium have not been considered anywhere. An analysis of such influence is carried out. The results of the analysis indicate the possibility of measuring the current value of stellar aberration using a uniaxial anisotropic medium. The concept of active light aberration is introduced. The proposed schemes of experiments of using the entrainment of a light flux by an anisotropic substance for measuring the current value of stellar aberration are investigated. It is concluded that it is possible to study the determination of the current velocity of an inertial system relative to the light flux.

  15. Jones phase microscopy of transparent and anisotropic samples.

    Science.gov (United States)

    Wang, Zhuo; Millet, Larry J; Gillette, Martha U; Popescu, Gabriel

    2008-06-01

    We developed an interferometric microscopy technique, referred to as Jones phase microscopy, capable of extracting the spatially resolved Jones polarization matrix associated with transparent and anisotropic samples. This is a generalization of quantitative phase imaging, which is recovered from one diagonal element of the measured matrix. The principle of the technique is demonstrated with measurements of a liquid crystal spatial light modulator and the potential for live cell imaging with experiments on live neurons in culture.

  16. Pseudorapidity Dependence of Anisotropic Azimuthal Flow with the ALICE Detector

    DEFF Research Database (Denmark)

    Hansen, Alexander Colliander

    In ultra-relativistic heavy-ion collisions a new state of matter known as the strongly interacting quark-gluon plasma (sQGP) is produced. A key observable in the study of the sQGP is anisotropic azimuthal ow. The anisotropies are described by ow harmonics, vn. In this thesis, bias arising from non...... Detector and Silicon Pixel Detector at the CERN Large Hadron Collider (LHC). The results are compared to other LHC experiments andprevious experiments at lower collision energies....

  17. Rational synthesis and self-assembly of anisotropic plasmonic nanoparticles

    OpenAIRE

    Scarabelli, Leonardo

    2016-01-01

    This thesis work has been carried out in the framework of the ERC Advanced Grant Plasmaquo (nº 267867), which focused on the development of novel nanostructured plasmonic materials based on crystalline assemblies of anisotropic nanoparticles, to be used as optical enhancers for the surface enhanced Raman scattering detection of bacterial Quorum Sensing signaling molecules. More specifically, the thesis was oriented toward the design of such nanostructures, and on the characterization of their...

  18. Anisotropic expansion of a thermal dipolar Bose gas

    OpenAIRE

    Tang, Yijun; Sykes, Andrew G.; Burdick, Nathaniel Q.; DiSciacca, Jack M.; Petrov, Dmitry S.; Lev, Benjamin L.

    2016-01-01

    We report on the anisotropic expansion of ultracold bosonic dysprosium gases at temperatures above quantum degeneracy and develop a quantitative theory to describe this behavior. The theory expresses the post-expansion aspect ratio in terms of temperature and microscopic collisional properties by incorporating Hartree-Fock mean-field interactions, hydrodynamic effects, and Bose-enhancement factors. Our results extend the utility of expansion imaging by providing accurate thermometry for dipol...

  19. Modeling Anisotropic Elastic Wave Propagation in Jointed Rock Masses

    Science.gov (United States)

    Hurley, R.; Vorobiev, O.; Ezzedine, S. M.; Antoun, T.

    2016-12-01

    We present a numerical approach for determining the anisotropic stiffness of materials with nonlinearly-compliant joints capable of sliding. The proposed method extends existing ones for upscaling the behavior of a medium with open cracks and inclusions to cases relevant to natural fractured and jointed rocks, where nonlinearly-compliant joints can undergo plastic slip. The method deviates from existing techniques by incorporating the friction and closure states of the joints, and recovers an anisotropic elastic form in the small-strain limit when joints are not sliding. We present the mathematical formulation of our method and use Representative Volume Element (RVE) simulations to evaluate its accuracy for joint sets with varying complexity. We then apply the formulation to determine anisotropic elastic constants of jointed granite found at the Nevada Nuclear Security Site (NNSS) where the Source Physics Experiments (SPE), a campaign of underground chemical explosions, are performed. Finally, we discuss the implementation of our numerical approach in a massively parallel Lagrangian code Geodyn-L and its use for studying wave propagation from underground explosions. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  20. Investigation of Anisotropic Bonded Magnets in Permanent Magnet Machine Applications

    Science.gov (United States)

    Khazdozian, H. A.; McCall, S. K.; Kramer, M. J.; Paranthaman, M. P.; Nlebedim, I. C.

    Rare earth elements (REE) provide the high energy product necessary for permanent magnets, such as sintered Nd2Fe14B, in many applications like wind energy generators. However, REEs are considered critical materials due to risk in their supply. To reduce the use of critical materials in permanent magnet machines, the performance of anisotropic bonded NdFeB magnets, aligned under varying magnetic field strength, was simulated using 3D finite element analysis in a 3MW direct-drive permanent magnet generator (DDPMG), with sintered N42 magnets used as a baseline for comparison. For direct substitution of the anisotropic bonded magnets, approximately 85% of the efficiency of the baseline model was achieved, irrespective of the alignment field. The torque and power generation of the DDPMG was not found to vary significantly with increase in the alignment field. Finally, design changes were studied to allow for the achievement of rated torque and power with the use of anisotropic bonded magnets, demonstrating the potential for reduction of critical materials in permanent magnets for renewable energy applications. This work was supported by the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office.

  1. Efficient anisotropic wavefield extrapolation using effective isotropic models

    KAUST Repository

    Alkhalifah, Tariq Ali

    2013-06-10

    Isotropic wavefield extrapolation is more efficient than anisotropic extrapolation, and this is especially true when the anisotropy of the medium is tilted (from the vertical). We use the kinematics of the wavefield, appropriately represented in the high-frequency asymptotic approximation by the eikonal equation, to develop effective isotropic models, which are used to efficiently and approximately extrapolate anisotropic wavefields using the isotropic, relatively cheaper, operators. These effective velocity models are source dependent and tend to embed the anisotropy in the inhomogeneity. Though this isotropically generated wavefield theoretically shares the same kinematic behavior as that of the first arrival anisotropic wavefield, it also has the ability to include all the arrivals resulting from a complex wavefield propagation. In fact, the effective models reduce to the original isotropic model in the limit of isotropy, and thus, the difference between the effective model and, for example, the vertical velocity depends on the strength of anisotropy. For reverse time migration (RTM), effective models are developed for the source and receiver fields by computing the traveltime for a plane wave source stretching along our source and receiver lines in a delayed shot migration implementation. Applications to the BP TTI model demonstrates the effectiveness of the approach.

  2. Stochastic self-propagating star formation with anisotropic probability distribution

    Science.gov (United States)

    Jungwiert, B.; Palous, J.

    1994-07-01

    We present a 2D computer code for stochastic self-propagating star formation (SSPSF) in differentially rotating galaxies. The isotropic probability distribution, used in previous models of Seiden, Gerola and Schulman (Seiden & Schulman, 1990, and references therein), is replaced by an anisotropic one. The motivation is provided by models of expanding large-scale supernova remnants (SNR) in disks with shear (Palous et al. 1990): the distortion of the SNR leads to uneven density distribution along its periphery and, consequently, to uneven distribution of new star forming sites. To model anisotropic SSPSF, we process in two steps: first, we eliminate artificial anisotropies inherent to the technique used by Seiden, Gerola and Schulman and, second, we define the probability ellipse on each star forming site. The anisotropy is characterized by its axes ratio and inclination with respect to the galactic center. We show that anisotropic SSPSF is able to produce highly organized spiral structures. Depending on the character of the probability ellipse, we can obtain continous spiral arms of different length, thickness and pitch angle. The relation of the probability ellipse to rotation curves interstellar medium (ISM) density and metallicity is discussed as well as its variation along the Hubble sequence and van den Bergh's luminosity classification of galaxies. To demonstrate applications, we compare our results with two different classes of galaxies: M 101-type grand-design spirals with open and robust arms and NGC 2841-type flocculent galaxies with thin and tightly wound arms.

  3. Anisotropic fluid spheres of embedding class one using Karmarkar condition

    Energy Technology Data Exchange (ETDEWEB)

    Maurya, S.K. [University of Nizwa, Department of Mathematical and Physical Sciences, College of Arts and Science, Nizwa (Oman); Maharaj, S.D. [School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal, Astrophysics and Cosmology Research Unit, Private Bag X54001, Durban (South Africa)

    2017-05-15

    We obtain a new anisotropic solution for spherically symmetric spacetimes by analyzing the Karmarkar embedding condition. For this purpose we construct a suitable form of one of the gravitational potentials to obtain a closed form solution. This form of the remaining gravitational potential allows us to solve the embedding equation and integrate the field equations. The resulting new anisotropic solution is well behaved, which can be utilized to construct realistic static fluid spheres. Also we estimated the masses and radii of fluid spheres for LMC X-4, EXO 1785-248, PSR J1903+327 and 4U 1820-30 by using observational data set values. The masses and radii obtained show that our anisotropic solution can represent fluid spheres to a very good degree of accuracy. The physical validity of the solution depends on the parameter values of a, b and c. The solution is well behaved for the wide range of parameters values 0.00393 ≤ a ≤ 0.0055, 0.0002 ≤ b ≤ 0.0025 and 0.0107 ≤ c ≤ 0.0155. The range of corresponding physical parameters for the different compact stars are 0.3266 ≤ v{sub r0} ≤ 0.3708, 0.1583 ≤ v{sub t0} ≤ 0.2558, 0.3256 ≤ z{sub s} ≤ 0.4450 and 4.3587 ≤ Γ{sub 0} ≤ 5.6462. (orig.)

  4. Pattern formation of a nonlocal, anisotropic interaction model

    KAUST Repository

    Burger, Martin

    2017-11-24

    We consider a class of interacting particle models with anisotropic, repulsive–attractive interaction forces whose orientations depend on an underlying tensor field. An example of this class of models is the so-called Kücken–Champod model describing the formation of fingerprint patterns. This class of models can be regarded as a generalization of a gradient flow of a nonlocal interaction potential which has a local repulsion and a long-range attraction structure. In contrast to isotropic interaction models the anisotropic forces in our class of models cannot be derived from a potential. The underlying tensor field introduces an anisotropy leading to complex patterns which do not occur in isotropic models. This anisotropy is characterized by one parameter in the model. We study the variation of this parameter, describing the transition between the isotropic and the anisotropic model, analytically and numerically. We analyze the equilibria of the corresponding mean-field partial differential equation and investigate pattern formation numerically in two dimensions by studying the dependence of the parameters in the model on the resulting patterns.

  5. Tuning particle geometry of chemically anisotropic dumbbell-shaped colloids.

    Science.gov (United States)

    van Ravensteijn, Bas G P; Kegel, Willem K

    2017-03-15

    Chemically anisotropic dumbbell-shaped colloids are prepared starting from cross-linked polymer seed particles coated with a chlorinated outer layer. These chlorinated seeds are swollen with monomer. Subsequently, a liquid protrusion is formed on the surface of the seed particle by phase separation between the monomer and the swollen polymer network. Solidification of these liquid lobes by polymerization leads to the desired dumbbell-shaped colloids. The chlorine groups remain confined on the seed lobe of the particles, ensuring chemical anisotropy of the resulting particles. Exploiting the asymmetric distribution of the chemically reactive surface chlorine groups allows for site-specific surface modifications. Here we show that the geometry of the resulting chemically anisotropic dumbbells can be systematically tuned by a number of experimental parameters including the volume of styrene by which the seeds are swollen, the cross-link density of the chlorinated seeds and chemical composition/thickness of the chlorinated coating deposited on the seed particles. Being able to control the particle geometry, and therefore the Janus balance of these chemically anisotropic particles, provides a promising starting point for the synthesis of sophisticated building blocks for future (self-assembly) studies. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Anisotropic silk fibroin/gelatin scaffolds from unidirectional freezing

    Energy Technology Data Exchange (ETDEWEB)

    Asuncion, Maria Christine Tankeh, E-mail: christine.asuncion@u.nus.edu [National University of Singapore, Department of Biomedical Engineering (Singapore); Goh, James Cho-Hong [National University of Singapore, Department of Biomedical Engineering (Singapore); National University of Singapore, Department of Orthopedic Surgery (Singapore); Toh, Siew-Lok [National University of Singapore, Department of Biomedical Engineering (Singapore); National University of Singapore, Department of Mechanical Engineering (Singapore)

    2016-10-01

    Recent studies have underlined the importance of matching scaffold properties to the biological milieu. Tissue, and thus scaffold, anisotropy is one such property that is important yet sometimes overlooked. Methods that have been used to achieve anisotropic scaffolds present challenges such as complicated fabrication steps, harsh processing conditions and toxic chemicals involved. In this study, unidirectional freezing was employed to fabricate anisotropic silk fibroin/gelatin scaffolds in a simple and mild manner. Morphological, mechanical, chemical and cellular compatibility properties were investigated, as well as the effect of the addition of gelatin to certain properties of the scaffold. It was shown that scaffold properties were suitable for cell proliferation and that mesenchymal stem cells were able to align themselves along the directed fibers. The fabricated scaffolds present a platform that can be used for anisotropic tissue engineering applications such as cardiac patches. - Highlights: • Silk/gelatin scaffolds with unidirectional alignment were fabricated using a simple and scalable process • Presence of gelatin in silk resulted to lesser shrinkage, better water retention and improved cell proliferation. • Mesenchymal stem cells were shown to align themselves according to the fiber alignment.

  7. Nanoparticle-Structured Highly Sensitive and Anisotropic Gauge Sensors.

    Science.gov (United States)

    Zhao, Wei; Luo, Jin; Shan, Shiyao; Lombardi, Jack P; Xu, Yvonne; Cartwright, Kelly; Lu, Susan; Poliks, Mark; Zhong, Chuan-Jian

    2015-09-16

    The ability to tune gauge factors in terms of magnitude and orientation is important for wearable and conformal electronics. Herein, a sensor device is described which is fabricated by assembling and printing molecularly linked thin films of gold nanoparticles on flexible microelectrodes with unusually high and anisotropic gauge factors. A sharp difference in gauge factors up to two to three orders of magnitude between bending perpendicular (B(⊥)) and parallel (B(||)) to the current flow directions is observed. The origin of the unusual high and anisotropic gauge factors is analyzed in terms of nanoparticle size, interparticle spacing, interparticle structure, and other parameters, and by considering the theoretical aspects of electron conduction mechanism and percolation pathway. A critical range of resistivity where a very small change in strain and the strain orientation is identified to impact the percolation pathway in a significant way, leading to the high and anisotropic gauge factors. The gauge anisotropy stems from molecular and nanoscale fine tuning of interparticle properties of molecularly linked nanoparticle assembly on flexible microelectrodes, which has important implication for the design of gauge sensors for highly sensitive detection of deformation in complex sensing environment or on complex curved surfaces such as wearable electronics and skin sensors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Sound localization in an anisotropic plate using electret microphones.

    Science.gov (United States)

    Hoseini Sabzevari, S Amir; Moavenian, Majid

    2017-01-01

    Acoustic source localization without knowing the velocity profile in anisotropic plates is still one of the most challenging areas in this field. The current time-of-flight based approaches for localization in anisotropic media, are based on using six high sampling sensors. The number of sensors and the corresponding large amount of data, would make those methods inefficient in practical applications. Although there are many different non-time-of-flight based approaches such as machine learning, or soft computing based methods that can be used for localization with a less number of sensors, they are not as accurate as time-of-flight based techniques. In this article, a new approach which requires only four low sampling rate sensors to localize acoustic source in an anisotropic plate is proposed. In this technique, four electret low sampling rate sensors in two clusters are installed on the plate surface. The presented method uses attenuation analysis in a suitable frequency band to decrease the number of sensors. The approach is experimentally tested and verified on an airplane composite nose by applying artificially generated acoustic emissions (Hsu-Nielsen source). The results reveal that the accuracy of proposed technique depends on distinction of dominant frequency band. A stethoscope as a physical filter is employed to reduce the sensitivity of the technique and delineation of frequency band. The suggested technique improves the accuracy of localization prediction. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Overview of thermal conductivity models of anisotropic thermal insulation materials

    Science.gov (United States)

    Skurikhin, A. V.; Kostanovsky, A. V.

    2017-11-01

    Currently, the most of existing materials and substances under elaboration are anisotropic. It makes certain difficulties in the study of heat transfer process. Thermal conductivity of the materials can be characterized by tensor of the second order. Also, the parallelism between the temperature gradient vector and the density of heat flow vector is violated in anisotropic thermal insulation materials (TIM). One of the most famous TIM is a family of integrated thermal insulation refractory material («ITIRM»). The main component ensuring its properties is the «inflated» vermiculite. Natural mineral vermiculite is ground into powder state, fired by gas burner for dehydration, and its precipitate is then compressed. The key feature of thus treated batch of vermiculite is a package structure. The properties of the material lead to a slow heating of manufactured products due to low absorption and high radiation reflection. The maximum of reflection function is referred to infrared spectral region. A review of current models of heat propagation in anisotropic thermal insulation materials is carried out, as well as analysis of their thermal and optical properties. A theoretical model, which allows to determine the heat conductivity «ITIRM», can be useful in the study of thermal characteristics such as specific heat capacity, temperature conductivity, and others. Materials as «ITIRM» can be used in the metallurgy industry, thermal energy and nuclear power-engineering.

  10. Surface waves in an heterogeneous anisotropic continental lithosphere

    Science.gov (United States)

    Maupin, V.

    2003-04-01

    At global as well as at regional scale, the lithosphere appears usually faster to Love waves than to Rayleigh waves. This Love-Rayleigh discrepancy can be modelled by introducing transverse isotropy in the mantle. In continental structures, the amount of transverse isotropy necessary to explain the discrepancy is however often quite large and not compatible with results of SKS-splitting analysis and azimuthal variation of surface wave velocities, at least in the simple framework of large scale uniform olivine orientation in the continental lithosphere. Models where the orientation of the olivine is incoherent at the scale of a few hundred km have been proposed to reconcile the different datasets, but the surface wave characteristics in such anisotropic heterogeneous models have not yet been analysed in detail. Using a mode-coupling scheme for calculating surface wave propagation in heterogeneous anisotropic structures, we analyse the characteristics of Rayleigh and Love waves in such laterally varying anisotropic models. We generate 3-D stochastic models of olivine orientation with different characteristics: preferred orientation dominantly horizontal, vertical or equally distributed in all directions, and use different correlation lengths in the horizontal and vertical directions to constrain the scale at which the anisotropy is coherent. We analyse the apparent Love-Rayleigh discrepancy and the phase velocity azimuthal variation these models generate and the mode-coupling and polarisation anomalies they produce.

  11. Isothermal anisotropic magnetoresistance in antiferromagnetic metallic IrMn.

    Science.gov (United States)

    Galceran, R; Fina, I; Cisneros-Fernández, J; Bozzo, B; Frontera, C; López-Mir, L; Deniz, H; Park, K-W; Park, B-G; Balcells, Ll; Martí, X; Jungwirth, T; Martínez, B

    2016-10-20

    Antiferromagnetic spintronics is an emerging field; antiferromagnets can improve the functionalities of ferromagnets with higher response times, and having the information shielded against external magnetic field. Moreover, a large list of aniferromagnetic semiconductors and metals with Néel temperatures above room temperature exists. In the present manuscript, we persevere in the quest for the limits of how large can anisotropic magnetoresistance be in antiferromagnetic materials with very large spin-orbit coupling. We selected IrMn as a prime example of first-class moment (Mn) and spin-orbit (Ir) combination. Isothermal magnetotransport measurements in an antiferromagnetic-metal(IrMn)/ferromagnetic-insulator thin film bilayer have been performed. The metal/insulator structure with magnetic coupling between both layers allows the measurement of the modulation of the transport properties exclusively in the antiferromagnetic layer. Anisotropic magnetoresistance as large as 0.15% has been found, which is much larger than that for a bare IrMn layer. Interestingly, it has been observed that anisotropic magnetoresistance is strongly influenced by the field cooling conditions, signaling the dependence of the found response on the formation of domains at the magnetic ordering temperature.

  12. Anisotropic diffusion of volatile pollutants at air-water interface

    Directory of Open Access Journals (Sweden)

    Li-ping Chen

    2013-04-01

    Full Text Available The volatile pollutants that spill into natural waters cause water pollution. Air pollution arises from the water pollution because of volatilization. Mass exchange caused by turbulent fluctuation is stronger in the direction normal to the air-water interface than in other directions due to the large density difference between water and air. In order to explore the characteristics of anisotropic diffusion of the volatile pollutants at the air-water interface, the relationship between velocity gradient and mass transfer rate was established to calculate the turbulent mass diffusivity. A second-order accurate smooth transition differencing scheme (STDS was proposed to guarantee the boundedness for the flow and mass transfer at the air-water interface. Simulations and experiments were performed to study the trichloroethylene (C2HCl3 release. By comparing the anisotropic coupling diffusion model, isotropic coupling diffusion model, and non-coupling diffusion model, the features of the transport of volatile pollutants at the air-water interface were determined. The results show that the anisotropic coupling diffusion model is more accurate than the isotropic coupling diffusion model and non-coupling diffusion model. Mass transfer significantly increases with the increase of the air-water relative velocity at a low relative velocity. However, at a higher relative velocity, an increase in the relative velocity has no effect on mass transfer.

  13. Surface Waves Propagating on Grounded Anisotropic Dielectric Slab

    Directory of Open Access Journals (Sweden)

    Zhuozhu Chen

    2018-01-01

    Full Text Available This paper investigates the characteristics of surface waves propagating on a grounded anisotropic dielectric slab. Distinct from the existing analyses that generally assume that the fields of surface wave uniformly distribute along the transverse direction of the infinitely large grounded slab, our method takes into account the field variations along the transverse direction of a finite-width slab. By solving Maxwell’s equations in closed-form, it is revealed that no pure transverse magnetic (TM or transverse electric (TE mode exists if the fields are non-uniformly distributed along the transverse direction of the grounded slab. Instead, two hybrid modes, namely quasi-TM and quasi-TE modes, are supported. In addition, the propagation characteristics of two hybrid modes supported by the grounded anisotropic slab are analyzed in terms of the slab thickness, slab width, as well as the relative permittivity tensor of the anisotropic slab. Furthermore, different methods are employed to compare the analyses, as well as to validate our derivations. The proposed method is very suitable for practical engineering applications.

  14. A methodology for developing anisotropic AAA phantoms via additive manufacturing.

    Science.gov (United States)

    Ruiz de Galarreta, Sergio; Antón, Raúl; Cazón, Aitor; Finol, Ender A

    2017-05-24

    An Abdominal Aortic Aneurysm (AAA) is a permanent focal dilatation of the abdominal aorta at least 1.5 times its normal diameter. The criterion of maximum diameter is still used in clinical practice, although numerical studies have demonstrated the importance of biomechanical factors for rupture risk assessment. AAA phantoms could be used for experimental validation of the numerical studies and for pre-intervention testing of endovascular grafts. We have applied multi-material 3D printing technology to manufacture idealized AAA phantoms with anisotropic mechanical behavior. Different composites were fabricated and the phantom specimens were characterized by biaxial tensile tests while using a constitutive model to fit the experimental data. One composite was chosen to manufacture the phantom based on having the same mechanical properties as those reported in the literature for human AAA tissue; the strain energy and anisotropic index were compared to make this choice. The materials for the matrix and fibers of the selected composite are, respectively, the digital materials FLX9940 and FLX9960 developed by Stratasys. The fiber proportion for the composite is equal to 0.15. The differences between the composite behavior and the AAA tissue are small, with a small difference in the strain energy (0.4%) and a maximum difference of 12.4% in the peak Green strain ratio. This work represents a step forward in the application of 3D printing technology for the manufacturing of AAA phantoms with anisotropic mechanical behavior. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Effective Elliptic Models for Efficient Wavefield Extrapolation in Anisotropic Media

    KAUST Repository

    Waheed, Umair bin

    2014-05-01

    Wavefield extrapolation operator for elliptically anisotropic media offers significant cost reduction compared to that of transversely isotropic media (TI), especially when the medium exhibits tilt in the symmetry axis (TTI). However, elliptical anisotropy does not provide accurate focusing for TI media. Therefore, we develop effective elliptically anisotropic models that correctly capture the kinematic behavior of the TTI wavefield. Specifically, we use an iterative elliptically anisotropic eikonal solver that provides the accurate traveltimes for a TI model. The resultant coefficients of the elliptical eikonal provide the effective models. These effective models allow us to use the cheaper wavefield extrapolation operator for elliptic media to obtain approximate wavefield solutions for TTI media. Despite the fact that the effective elliptic models are obtained by kinematic matching using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including the frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy tradeoff for wavefield computations in TTI media, considering the cost prohibitive nature of the problem. We demonstrate the applicability of the proposed approach on the BP TTI model.

  16. Computational Study of Subdural Cortical Stimulation: Effects of Simulating Anisotropic Conductivity on Activation of Cortical Neurons.

    Directory of Open Access Journals (Sweden)

    Hyeon Seo

    Full Text Available Subdural cortical stimulation (SuCS is an appealing method in the treatment of neurological disorders, and computational modeling studies of SuCS have been applied to determine the optimal design for electrotherapy. To achieve a better understanding of computational modeling on the stimulation effects of SuCS, the influence of anisotropic white matter conductivity on the activation of cortical neurons was investigated in a realistic head model. In this paper, we constructed pyramidal neuronal models (layers 3 and 5 that showed primary excitation of the corticospinal tract, and an anatomically realistic head model reflecting complex brain geometry. The anisotropic information was acquired from diffusion tensor magnetic resonance imaging (DT-MRI and then applied to the white matter at various ratios of anisotropic conductivity. First, we compared the isotropic and anisotropic models; compared to the isotropic model, the anisotropic model showed that neurons were activated in the deeper bank during cathodal stimulation and in the wider crown during anodal stimulation. Second, several popular anisotropic principles were adapted to investigate the effects of variations in anisotropic information. We observed that excitation thresholds varied with anisotropic principles, especially with anodal stimulation. Overall, incorporating anisotropic conductivity into the anatomically realistic head model is critical for accurate estimation of neuronal responses; however, caution should be used in the selection of anisotropic information.

  17. TOPICAL REVIEW Textured silicon nitride: processing and anisotropic properties

    Directory of Open Access Journals (Sweden)

    Xinwen Zhu and Yoshio Sakka

    2008-01-01

    Full Text Available Textured silicon nitride (Si3N4 has been intensively studied over the past 15 years because of its use for achieving its superthermal and mechanical properties. In this review we present the fundamental aspects of the processing and anisotropic properties of textured Si3N4, with emphasis on the anisotropic and abnormal grain growth of β-Si3N4, texture structure and texture analysis, processing methods and anisotropic properties. On the basis of the texturing mechanisms, the processing methods described in this article have been classified into two types: hot-working (HW and templated grain growth (TGG. The HW method includes the hot-pressing, hot-forging and sinter-forging techniques, and the TGG method includes the cold-pressing, extrusion, tape-casting and strong magnetic field alignment techniques for β-Si3N4 seed crystals. Each processing technique is thoroughly discussed in terms of theoretical models and experimental data, including the texturing mechanisms and the factors affecting texture development. Also, methods of synthesizing the rodlike β-Si3N4 single crystals are presented. Various anisotropic properties of textured Si3 N4 and their origins are thoroughly described and discussed, such as hardness, elastic modulus, bending strength, fracture toughness, fracture energy, creep behavior, tribological and wear behavior, erosion behavior, contact damage behavior and thermal conductivity. Models are analyzed to determine the thermal anisotropy by considering the intrinsic thermal anisotropy, degree of orientation and various microstructure factors. Textured porous Si3N4 with a unique microstructure composed of oriented elongated β-Si3N4 and anisotropic pores is also described for the first time, with emphasis on its unique mechanical and thermal-mechanical properties. Moreover, as an important related material, textured α-Sialon is also reviewed, because the presence of elongated α-Sialon grains allows the production of textured

  18. Analytical Method and Semianalytical Method for Analysis of Scattering by Anisotropic Sphere: A Review

    Directory of Open Access Journals (Sweden)

    Chao Wan

    2012-01-01

    Full Text Available The history of methods for the electromagnetic scattering by an anisotropic sphere has been reviewed. Two main methods, angular expansion method and T-matrix method, which are widely used for the anisotropic sphere, are expressed in Cartesian coordinate firstly. The comparison of those and the further exploration on the scattering field are illustrated afterwards. Based on the most general form concluded by variable separation method, the coupled electric field and magnetic field of radial anisotropic sphere can be derived. By simplifying the condition, simpler case of uniaxial anisotropic media is expressed with confirmed coefficients for the internal and external field. Details of significant phenomenon are presented.

  19. Materials Research Society Symposium Proceedings Volume 635. Anisotropic Nanoparticles - Synthesis, Characterization and Applications

    National Research Council Canada - National Science Library

    Lyon, L

    2000-01-01

    This volume contains a series of papers originally presented at Symposium C, "Anisotropic Nanoparticles Synthesis, Characterization and Applications," at the 2000 MRS Fall Meeting in Boston, Massachusetts...

  20. An accurate discontinuous Galerkin method for solving point-source Eikonal equation in 2-D heterogeneous anisotropic media

    Science.gov (United States)

    Le Bouteiller, P.; Benjemaa, M.; Métivier, L.; Virieux, J.

    2018-03-01

    Accurate numerical computation of wave traveltimes in heterogeneous media is of major interest for a large range of applications in seismics, such as phase identification, data windowing, traveltime tomography and seismic imaging. A high level of precision is needed for traveltimes and their derivatives in applications which require quantities such as amplitude or take-off angle. Even more challenging is the anisotropic case, where the general Eikonal equation is a quartic in the derivatives of traveltimes. Despite their efficiency on Cartesian meshes, finite-difference solvers are inappropriate when dealing with unstructured meshes and irregular topographies. Moreover, reaching high orders of accuracy generally requires wide stencils and high additional computational load. To go beyond these limitations, we propose a discontinuous-finite-element-based strategy which has the following advantages: (1) the Hamiltonian formalism is general enough for handling the full anisotropic Eikonal equations; (2) the scheme is suitable for any desired high-order formulation or mixing of orders (p-adaptivity); (3) the solver is explicit whatever Hamiltonian is used (no need to find the roots of the quartic); (4) the use of unstructured meshes provides the flexibility for handling complex boundary geometries such as topographies (h-adaptivity) and radiation boundary conditions for mimicking an infinite medium. The point-source factorization principles are extended to this discontinuous Galerkin formulation. Extensive tests in smooth analytical media demonstrate the high accuracy of the method. Simulations in strongly heterogeneous media illustrate the solver robustness to realistic Earth-sciences-oriented applications.

  1. Multimesh anisotropic adaptivity for the Boltzmann transport equation

    International Nuclear Information System (INIS)

    Baker, C.M.J.; Buchan, A.G.; Pain, C.C.; Farrell, P.E.; Eaton, M.D.; Warner, P.

    2013-01-01

    Highlights: ► We solve the Boltzmann transport equation using anisotropically adaptive finite element meshes. ► The finite element mesh is resolved with minimal user input. ► Anisotropic adaptivity uses less elements than adaptive mesh refinement for the same finite element error. ► This paper also demonstrates the use of separate meshes for each energy group within the multigroup discretisation. ► The methods are applied to a range of fixed source and eigenvalue problems. - Abstract: This article presents a new adaptive finite element based method for the solution of the spatial dimensions of the Boltzmann transport equation. The method applies a curvature based error metric to locate the under and over resolved regions of a solution and this, in turn, is used to guide the refinement and coarsening of the spatial mesh. The error metrics and re-meshing procedures are designed such that they enable anisotropic resolution to form in the mesh should it be appropriate to do so. The adaptive mesh enables the appropriate resolution to be applied throughout the whole domain of a problem and so increase the efficiency of the solution procedure. Another new approach is also described that allows independent adaptive meshes to form for each of the energy group fluxes. The use of independent meshes can significantly improve computational efficiency when solving problems where the different group fluxes require high resolution over different regions. The mesh to mesh interpolation is made possible through the use of a ‘supermeshing’ procedure that ensures the conservation of particles when calculating the group to group scattering sources. Finally it is shown how these methods can be incorporated within a solver to resolve both fixed source and eigenvalue problems. A selection of both fixed source and eigenvalue problems are solved in order to demonstrate the capabilities of these methods

  2. Quarkonium states in an anisotropic quark-gluon plasma

    Energy Technology Data Exchange (ETDEWEB)

    Guo Yun

    2009-09-10

    In this work we study the properties of quarkonium states in a quark-gluon plasma which, due to expansion and non-zero viscosity, exhibits a local anisotropy in momentum space. We determine the hard-loop resummed gluon propagator in an anisotropic QCD plasma in general linear gauges and define a potential between heavy quarks from the Fourier transform of its static limit. This potential which arises due to one-gluon exchange describes the force between a quark and anti-quark at short distances. It is closer to the vacuum potential as compared to the isotropic Debye screened potential which indicates the reduced screening in an anisotropic QCD plasma. In addition, angular dependence appears in the potential; we find that there is stronger attraction on distance scales on the order of the inverse Debye mass for quark pairs aligned along the direction of anisotropy than for transverse alignment. The potential at long distances, however, is non-perturbative and modeled as a QCD string which is screened at the same scale as the Coulomb field. At asymptotic separation the potential energy is non-zero and inversely proportional to the temperature. With a phenomenological potential model which incorporates the different behaviors at short and long distances, we solve the three-dimensional Schroedinger equation. Our numerical results show that quarkonium binding is stronger at non-vanishing viscosity and expansion rate, and that the anisotropy leads to polarization of the P-wave states. Furthermore, we determine viscosity corrections to the imaginary part of the heavy-quark potential in the weak-coupling hard-loop approximation. The imaginary part is found to be smaller (in magnitude) than at vanishing viscosity. This implies a smaller decay width of quarkonium bound states in an anisotropic plasma. (orig.)

  3. Anisotropic Alfven-ballooning modes in the Earth's magnetosphere

    International Nuclear Information System (INIS)

    Chan, A.A.; Xia, Mengfen; Chen, Liu

    1993-05-01

    We have carried out a theoretical analysis of the stability and parallel structure of coupled shear-Alfven and slow-magnetosonic waves in the Earth's inner magnetosphere including effects of finite anisotropic plasma pressure. Multiscale perturbation analysis of the anisotropic Grad-Shafranov equation yields an approximate self-consistent magnetohydrodynamic (MHD) equilibrium. This MHD equilibrium is used in the numerical solution of a set of eigenmode equations which describe the field line eigenfrequency, linear stability, and parallel eigenmode structure. We call these modes anisotropic Alfven-ballooning modes. The main results are: The field line eigenfrequency can be significantly lowered by finite pressure effects. The parallel mode structure of the transverse wave components is fairly insensitive to changes in the plasma pressure but the compressional magnetic component can become highly peaked near the magnetic equator due to increased pressure, especially when P perpendicular > P parallel. For the isotropic case ballooning instability can occur when the ratio of the plasma pressure to the magnetic pressure, exceeds a critical value β o B ∼ 3.5 at the equator. Compared to the isotropic case the critical beta value is lowered by anisotropy, either due to decreased field-line-bending stabilization when P parallel > P perpendicular, or due to increased ballooning-mirror destabilization when P perpendicular > P parallel. We use a ''β-6 stability diagram'' to display the regions of instability with respect to the equatorial values of the parameters bar β and δ, where bar β = (1/3)(β parallel + 2 β perpendicular) is an average beta value and δ = 1 - P parallel/P perpendicular is a measure of the plasma anisotropy

  4. Numerical investigation of nanoparticles transport in anisotropic porous media

    KAUST Repository

    Salama, Amgad

    2015-07-13

    In this work the problem related to the transport of nanoparticles in anisotropic porous media is investigated numerically using the multipoint flux approximation. Anisotropy of porous media properties are an essential feature that exist almost everywhere in subsurface formations. In anisotropic media, the flux and the pressure gradient vectors are no longer collinear and therefore interesting patterns emerge. The transport of nanoparticles in subsurface formations is affected by several complex processes including surface charges, heterogeneity of nanoparticles and soil grain collectors, interfacial dynamics of double-layer and many others. We use the framework of the theory of filtration in this investigation. Processes like particles deposition, entrapment, as well as detachment are accounted for. From the numerical methods point of view, traditional two-point flux finite difference approximation cannot handle anisotropy of media properties. Therefore, in this work we use the multipoint flux approximation (MPFA). In this technique, the flux components are affected by more neighboring points as opposed to the mere two points that are usually used in traditional finite volume methods. We also use the experimenting pressure field approach which automatically constructs the global system of equations by solving multitude of local problems. This approach facilitates to a large extent the construction of the global system. A set of numerical examples is considered involving two-dimensional rectangular domain. A source of nanoparticles is inserted in the middle of the anisotropic layer. We investigate the effects of both anisotropy angle and anisotropy ratio on the transport of nanoparticles in saturated porous media. It is found that the concentration plume and porosity contours follow closely the principal direction of anisotropy of permeability of the central domain.

  5. Quarkonium states in an anisotropic quark-gluon plasma

    International Nuclear Information System (INIS)

    Guo Yun

    2009-01-01

    In this work we study the properties of quarkonium states in a quark-gluon plasma which, due to expansion and non-zero viscosity, exhibits a local anisotropy in momentum space. We determine the hard-loop resummed gluon propagator in an anisotropic QCD plasma in general linear gauges and define a potential between heavy quarks from the Fourier transform of its static limit. This potential which arises due to one-gluon exchange describes the force between a quark and anti-quark at short distances. It is closer to the vacuum potential as compared to the isotropic Debye screened potential which indicates the reduced screening in an anisotropic QCD plasma. In addition, angular dependence appears in the potential; we find that there is stronger attraction on distance scales on the order of the inverse Debye mass for quark pairs aligned along the direction of anisotropy than for transverse alignment. The potential at long distances, however, is non-perturbative and modeled as a QCD string which is screened at the same scale as the Coulomb field. At asymptotic separation the potential energy is non-zero and inversely proportional to the temperature. With a phenomenological potential model which incorporates the different behaviors at short and long distances, we solve the three-dimensional Schroedinger equation. Our numerical results show that quarkonium binding is stronger at non-vanishing viscosity and expansion rate, and that the anisotropy leads to polarization of the P-wave states. Furthermore, we determine viscosity corrections to the imaginary part of the heavy-quark potential in the weak-coupling hard-loop approximation. The imaginary part is found to be smaller (in magnitude) than at vanishing viscosity. This implies a smaller decay width of quarkonium bound states in an anisotropic plasma. (orig.)

  6. Tunneling anisotropic magnetoresistance in single-molecule magnet junctions

    Science.gov (United States)

    Xie, Haiqing; Wang, Qiang; Jiao, Hujun; Liang, J.-Q.

    2012-08-01

    We theoretically investigate quantum transport through single-molecule magnet (SMM) junctions with ferromagnetic and normal-metal leads in the sequential regime. The current obtained by means of the rate-equation gives rise to the tunneling anisotropic magnetoresistance (TAMR), which varies with the angle between the magnetization direction of ferromagnetic lead and the easy axis of SMM. The angular dependence of TAMR can serve as a probe to determine experimentally the easy axis of SMM. Moreover, it is demonstrated that both the magnitude and the sign of TAMR are tunable by the bias voltage, suggesting a new spin-valve device with only one magnetic electrode in molecular spintronics.

  7. Self-assembly in the systems of magnetic anisotropic nanoparticles

    Science.gov (United States)

    Gudkova, A. V.; Pyanzina, E. S.

    2017-11-01

    This paper presents the complex investigation of the system of magnetic anisotropic nanoparticles using computer simulations in a wide range of the system's parameters. The cluster analysis was made, various average characteristics of the formed clusters were calculated and the initial magnetic susceptibility and the radial distribution function were computed. It was shown that via changing the nanoparticles characteristics (their shape and the values of the magnetic moments) it's possible to change macroscopic response of the system, that implements the idea of tuning and design new materials with controllable properties.

  8. Outflow and clogging of shape-anisotropic grains in hoppers

    Science.gov (United States)

    Stannarius, Ralf; Ashour, Ahmed; Wegner, Sandra; BöRzsöNyi, Tamas

    Silos have been in use in human history for millennia, but still today, the discharge of grains from silos is a process with potential risks and imponderabilities. Models and quantitative predictions have been developed almost exclusively for spherical grains shapes. We study the discharge and clogging processes of shape-anisotropic grains in hoppers, and describe the peculiarities of these materials both in their dynamical properties and in the observed clogging structures. An attempt is made to adapt the well-known equations for spherical material to describe anisometric particles. Funding by DAAD and M\\x96B is acknowledged. A. A. acknowledges a scholarship from Future University, Egypt.

  9. Anisotropic superconducting state parameters of Tl-2212 superconductors

    International Nuclear Information System (INIS)

    Khaskalam, Amit K.; Singh, R.K.; Varshney, Dinesh

    2001-01-01

    We have estimated the superconducting state parameters and their anisotropy in thallium based superconductors (Tl-2212), in the frame work of Fermi liquid approach. Determination of the effective mass of the charge carriers from the Fermi velocity and estimated anisotropic superconducting state parameters, particularly, the magnetic penetration depth along and perpendicular to the conducting plane. The coherence length along and perpendicular to the ab plane is evaluated and appears to be higher. The temperature dependence of penetration depth, their anisotropy and Ginsburg Landau parameter for optimised doped Tl based cuprates shows the power law. The technique permits a consistency with the reported data. (author)

  10. Tungsten based anisotropic metamaterial as an ultra-broadband absorber

    DEFF Research Database (Denmark)

    Lin, Yinyue; Cui, Yanxia; Ding, Fei

    2017-01-01

    : We show theoretically that an array of tungsten/germanium anisotropic nano-cones placed on top of a reflective substrate can absorb light at the wavelength range from 0.3 μm to 9 μm with an average absorption efficiency approaching 98%. It is found that the excitation of multiple orders of slow...... of the nano-cones and the interaction between neighboring nano-cones is quite weak. Our proposal has some potential applications in the areas of solar energy harvesting and thermal emitters....

  11. Anisotropic magnetotelluric inversion using a mutual information constraint

    Science.gov (United States)

    Mandolesi, E.; Jones, A. G.

    2012-12-01

    In recent years, several authors pointed that the electrical conductivity of many subsurface structures cannot be described properly by a scalar field. With the development of field devices and techniques, data quality improved to the point that the anisotropy in conductivity of rocks (microscopic anisotropy) and tectonic structures (macroscopic anisotropy) cannot be neglected. Therefore a correct use of high quality data has to include electrical anisotropy and a correct interpretation of anisotropic data characterizes directly a non-negligible part of the subsurface. In this work we test an inversion routine that takes advantage of the classic Levenberg-Marquardt (LM) algorithm to invert magnetotelluric (MT) data generated from a bi-dimensional (2D) anisotropic domain. The LM method is routinely used in inverse problems due its performance and robustness. In non-linear inverse problems -such the MT problem- the LM method provides a spectacular compromise betwee quick and secure convergence at the price of the explicit computation and storage of the sensitivity matrix. Regularization in inverse MT problems has been used extensively, due to the necessity to constrain model space and to reduce the ill-posedness of the anisotropic MT problem, which makes MT inversions extremely challenging. In order to reduce non-uniqueness of the MT problem and to reach a model compatible with other different tomographic results from the same target region, we used a mutual information (MI) based constraint. MI is a basic quantity in information theory that can be used to define a metric between images, and it is routinely used in fields as computer vision, image registration and medical tomography, to cite some applications. We -thus- inverted for the model that best fits the anisotropic data and that is the closest -in a MI sense- to a tomographic model of the target area. The advantage of this technique is that the tomographic model of the studied region may be produced by any

  12. Chemical phase analysis of seed mediated synthesized anisotropic silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Bharti, Amardeep, E-mail: abharti@pu.ac.in; Goyal, Navdeep [Department of Physics, Panjab University, Chandigarh, INDIA-160014 (India); Singh, Suman; Singla, M. L. [Agrionics, Central Scientific Instruments Organization, CSIR, Chandigarh, INDIA-160030 (India)

    2015-08-28

    Noble-metal nanoparticles are of great interest because of its broad applications almost in every stream (i.e. biology, chemistry and engineering) due to their unique size/shape dependant properties. In this paper, chemical phase of seed mediated synthesized anisotropic silver nanoparticle (AgNPs) has been investigated via fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). These nanaoparticles were synthesized by seed-growth method controlled by urea and dextrose results to highly stable 12-20 nm particle size revealed by zeta potential and transmission electron microscopy (TEM)

  13. Anisotropic structure beneath central Java from local earthquake tomography

    Science.gov (United States)

    Koulakov, Ivan; Jakovlev, Andrey; Luehr, Birger G.

    2009-02-01

    In this study we present the new tomographic code ANITA which provides 3-D anisotropic P and isotropic S velocity distribution based on P and S traveltimes from local seismicity. For the P anisotropic model, we determine four parameters for each parameterization cell. This represents an orthorhombic anisotropy with one predefined direction oriented vertically. Three of the parameters describe slowness variations along three horizontal orientations with azimuths of 0°, 60°, and 120°, and one is a perturbation along the vertical axis. The nonlinear iterative inversion procedure is similar to that used in the LOTOS code. We have implemented this algorithm for the updated data set of central Java, part of which was previously used for the isotropic inversion. It was obtained that the crustal and uppermost mantle velocity structure beneath central Java is strongly anisotropic with 7-10% of maximal difference between slow and fast velocity in different directions. In the forearc (area between southern coast and volcanoes), the structure of both isotropic and anisotropic structure is strongly heterogeneous. Variety of anisotropy orientations and highly contrasted velocity patterns can be explained by a complex block structure of the crust. Beneath volcanoes we observe faster velocities in vertical direction, which is probably an indicator for vertically oriented structures (channels, dykes). In the crust beneath the middle part of central Java, north to Merapi and Lawu volcanoes, we observe a large and very intense anomaly with a velocity decrease of up to 30% and 35% for P and S models, respectively. Inside this anomaly E-W orientation of fast velocity takes place, probably caused by regional extension stress regime. In a vertical section we observe faster horizontal velocities inside this anomaly that might be explained by layering of sediments and/or penetration of quasi-horizontal lenses with molten magma. In the mantle, trench parallel anisotropy is observed

  14. Nonaxisymmetric radiative transfer in inhomogeneous cylindrical media with anisotropic scattering

    International Nuclear Information System (INIS)

    Grissa, H.; Askri, F.; Ben Salah, M.; Ben Nasrallah, S.

    2008-01-01

    In this paper, the control volume finite element method (CVFEM) is applied for the first time to solve nonaxisymmetric radiative transfer in inhomogeneous, emitting, absorbing and anisotropic scattering cylindrical media. Mathematical formulations as well as numerical implementation are given and the final discretized equations are based on similar meshes used for convective and conductive heat transfer in computational fluid dynamic analysis. In order to test the efficiency of the developed method, four nonaxisymmetric problems have been examined. Also, the grid dependence and the false scattering of the CVFEM are investigated and compared with the finite volume method and the discrete ordinates interpolation method

  15. Anisotropic tunneling resistance in a phosphorene-based magnetic barrier

    Science.gov (United States)

    Zhai, Feng; Hu, Wei; Lu, Junqiang

    2017-10-01

    We investigate the ballistic tunneling transport properties of a monolayer of black phosphorus under a magnetic barrier. The conductance of the system depends strongly on the orientation of the magnetic barrier, which is suppressed maximally when the magnetic barrier is oriented along the armchair direction. The mechanism relies on the highly anisotropic energy dispersion of phosphorene and the magnetic-barrier-induced suppression of available phase space for transmission. The magnetoresistance is enhanced by the reduction of the band gap under the same effective mass components.

  16. Aeroelastic modal dynamics of wind turbines including anisotropic effects

    DEFF Research Database (Denmark)

    Skjoldan, Peter Fisker

    and the computationally efficient implicit Floquet analysis in anisotropic conditions. The tool is validated against system identifications with the partial Floquet method on the nonlinear BHawC model of a 2.3 MW wind turbine. System identification results show that nonlinear effects on the 2.3 MW turbine in most cases....... These harmonics appear in calculated frequency responses of the turbine. Extreme wind shear changes the modal damping when the flow is separated due to an interaction between the periodic mode shape and the local aerodynamic damping influenced by a periodic variation in angle of attack....

  17. Theoretical assessment of sound absorption coefficient for anisotropic nonwovens

    Directory of Open Access Journals (Sweden)

    Klara Kalinova

    2012-03-01

    Full Text Available The anisotropy factor as a function of fiber arrangement, fiber fineness and sample thickness has been derived from the theories of soundwave transformation due to phase changing. The sound absorption coefficient of the anisotropic fibrous material is then theoretically calculated. The fibrous materials were prepared so that the fibers are arranged parallel (perpendicularly laid fiber web called STRUTO technology in the direction of soundwave propagation or perpendicularly (longitudinally laid fiber web to the direction of sound propagation. The sound absorption coefficient was measured due to the Impedance tube. The theoretical results are in good agreement with experimental findings.

  18. Anisotropic Third-Order Regularization for Sparse Digital Elevation Models

    KAUST Repository

    Lellmann, Jan

    2013-01-01

    We consider the problem of interpolating a surface based on sparse data such as individual points or level lines. We derive interpolators satisfying a list of desirable properties with an emphasis on preserving the geometry and characteristic features of the contours while ensuring smoothness across level lines. We propose an anisotropic third-order model and an efficient method to adaptively estimate both the surface and the anisotropy. Our experiments show that the approach outperforms AMLE and higher-order total variation methods qualitatively and quantitatively on real-world digital elevation data. © 2013 Springer-Verlag.

  19. Gaussian beam diffraction in weakly anisotropic inhomogeneous media

    Energy Technology Data Exchange (ETDEWEB)

    Kravtsov, Yu.A., E-mail: kravtsov@am.szczecin.p [Institute of Physics, Maritime University of Szczecin, Szczecin 70-500 (Poland); Space Research Institute, Russian Academy of Science, Moscow 117 997 (Russian Federation); Berczynski, P., E-mail: pawel.berczynski@ps.p [Institute of Physics, West Pomeranian University of Technology, Szczecin 70-310 (Poland); Bieg, B., E-mail: b.bieg@am.szczecin.p [Institute of Physics, Maritime University of Szczecin, Szczecin 70-500 (Poland)

    2009-08-10

    Combination of quasi-isotropic approximation (QIA) of geometric optics with paraxial complex geometric optics (PCGO) is suggested, which allows describing both diffraction and polarization evolution of Gaussian electromagnetic beams in weakly anisotropic inhomogeneous media. Combination QIA/PCGO reduces Maxwell equations to the system of the ordinary differential equations of the first order and radically simplifies solution of various problems, related to microwave plasma diagnostics, including plasma polarimetry, interferometry and refractometry in thermonuclear reactors. Efficiency of the method is demonstrated by the example of electromagnetic beam diffraction in a linear layer of magnetized plasma with parameters, modeling tokamak plasma in the project ITER.

  20. Wormhole solution of BD theory in an anisotropic radiation background

    Directory of Open Access Journals (Sweden)

    B. Nasre Esfahani

    2001-06-01

    Full Text Available   Time-dependent wormhole solution of the BD theory in an anisotropic radiation background is presented. It is also found that the BD scalar field depends only on time. This time dependency is in power-law form. It is shown that the wormhole geometry is valid for ω ≥ -3/2, and for any arbitrary positive values of . The GR limit of our solution is obtained for ω=0 , not for ω→∞ . Though the BD field can be non-exotic, the background material is entirely exotic.

  1. Comparing energy levels in isotropic and anisotropic potentials

    International Nuclear Information System (INIS)

    Pikovski, Alexander

    2015-01-01

    Qualitative information about the quantized energy levels of a system can be of great value. We study the relationship between the bound-state energies of an anisotropic potential and those of its spherical average. It is shown that the two ground-state energies satisfy an inequality, and there is a similar inequality for the first excited states. - Highlights: • Quantized energy levels in an arbitrary non-central potential are studied. • We derive inequalities between energies in a potential and its spherical average. • The results hold in three and two dimensions for any ground state and, with additional symmetry requirements for the first excited state.

  2. Quantum cosmology in an anisotropic n -dimensional universe

    Science.gov (United States)

    Alves-Júnior, F. A. P.; Pucheu, M. L.; Barreto, A. B.; Romero, C.

    2018-02-01

    We investigate quantum cosmological models in an n -dimensional anisotropic universe in the presence of a massless scalar field. Our basic inspiration comes from Chodos and Detweiler's classical model, which predicts interesting behavior of the extra dimension, shrinking down as time goes by. We work in the framework of a recent geometrical scalar-tensor theory of gravity. Classically, we obtain two distinct types of solutions. One of them has an initial singularity, while the other represents a static universe considered as a whole. By using the canonical approach to quantum cosmology, we investigate how quantum effects could have had an influence in the past history of these universes.

  3. Kelvin circulation in a cranked anisotropic oscillator + BCS mean field

    International Nuclear Information System (INIS)

    Rosensteel, G.; Goodman, A.L.; Tulane, U.

    1993-01-01

    The Kelvin circulation vector is the hermitian kinematical observable that measures the true character of nuclear rotation. For a rotating deformed nucleus modeled by a self-consistent cranked anisotropic oscillator mean field with BCS pairing, the expectation value of the Kelvin circulation operator depends upon the deformation and upon the strength of the pairing field. For zero pairing, the circulation acquires its rigid rotor value. As the pairing field increases, the circulation tends to zero, the irrotational flow limit. At critical values of the pairing field, the deformation and circulation make abrupt phase transitions

  4. An anisotropic three-fluid model for heavy ion reactions

    International Nuclear Information System (INIS)

    Lovas, I.; Zimanyi, J.; Csernai, L.P.; Greiner, W.

    1981-01-01

    The nucleons taking part in heavy ion reactions are considered as a three-fluid system. The first and second components correspond to the target and the projectile, while the thermalised nucleons produced in the course of the collision belong to the third component. Making use of the Boltzmann-equation, hydrodynamical equations are derived which yield also the anisotropy of the momentum distribution. The equation of state for anisotropic nuclear matter is derived from a field theoretical model in the mean field approximation. (Auth.)

  5. Anisotropic hydrodynamics, holography and the chiral magnetic effect

    International Nuclear Information System (INIS)

    Gahramanov, Ilmar; Kalaydzhyan, Tigran; Kirsch, Ingo; Hamburg Univ.

    2012-03-01

    We discuss a possible dependence of the chiral magnetic effect (CME) on the elliptic flow coefficient υ 2 . We first study this in a hydrodynamic model for a static anisotropic plasma with multiple anomalous U(1) currents. In the case of two charges, one axial and one vector, the CME formally appears as a first-order transport coefficient in the vector current. We compute this transport coefficient and show its dependence on υ 2 . We also determine the CME-coefficient from first-order corrections to the dual AdS background using the fluid-gravity duality. For small anisotropies, we find numerical agreement with the hydrodynamic result. (orig.)

  6. Electromagnetic fields due to dipole antennas over stratified anisotropic media.

    Science.gov (United States)

    Kong, J. A.

    1972-01-01

    Solutions to the problem of radiation of dipole antennas in the presence of a stratified anisotropic media are facilitated by decomposing a general wave field into transverse magnetic (TM) and transverse electric (TE) modes. Employing the propagation matrices, wave amplitudes in any region are related to those in any other regions. The reflection coefficients, which embed all the information about the geometrical configuration and the physical constituents of the medium, are obtained in closed form. In view of the general formulation, various special cases are discussed.

  7. Existence and uniqueness in anisotropic conductivity reconstruction with Faraday's law

    KAUST Repository

    Lee, Min-Gi

    2015-03-18

    We show that three sets of internal current densities are the right amount of data that give the existence and the uniqueness at the same time in reconstructing an anisotropic conductivity in two space dimensions. The curl free equation of Faraday’s law is taken instead of the usual divergence free equation of the electrical impedance to- mography. Boundary conditions related to given current densities are introduced which complete a well determined problem for conductivity reconstruction together with Fara- day’s law.

  8. Love wave dispersion in anisotropic visco-elastic medium

    Directory of Open Access Journals (Sweden)

    G. GIR SUBHASH

    1978-06-01

    Full Text Available The paper presents a study on Love wave propagation in a anisotropic
    visco-elastic layer overlying a rigid half space. The characteristic frequency
    equation is obtained and the variation of the wave number with frequency
    under the combined effect of visco-elasticity and anisotropy is analysed
    in detail. The results show that the effect of visco-elasticity on the
    wave is similar to that of anisotropy as long as the coefficient of anisotropy
    is less than unity.

  9. Anisotropic magnetoresistance components in (Ga,Mn)As

    Czech Academy of Sciences Publication Activity Database

    Rushforth, A.W.; Výborný, Karel; King, C.S.; Edmonds, K. W.; Campion, R. P.; Foxon, C. T.; Wunderlich, J.; Irvine, A.C.; Vašek, Petr; Novák, Vít; Olejník, Kamil; Sinova, J.; Jungwirth, Tomáš; Gallagher, B. L.

    2007-01-01

    Roč. 99, č. 14 (2007), 147207/1-147207/4 ISSN 0031-9007 R&D Projects: GA ČR GA202/05/0575; GA ČR GA202/04/1519; GA ČR GEFON/06/E002; GA MŠk LC510 Grant - others:UK(GB) GR/S81407/01 Institutional research plan: CEZ:AV0Z10100521 Keywords : ferromagnetic semiconductors * anisotropic magnetoresistence Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 6.944, year: 2007

  10. Highly Sensitive Flexible Magnetic Sensor Based on Anisotropic Magnetoresistance Effect.

    Science.gov (United States)

    Wang, Zhiguang; Wang, Xinjun; Li, Menghui; Gao, Yuan; Hu, Zhongqiang; Nan, Tianxiang; Liang, Xianfeng; Chen, Huaihao; Yang, Jia; Cash, Syd; Sun, Nian-Xiang

    2016-11-01

    A highly sensitive flexible magnetic sensor based on the anisotropic magnetoresistance effect is fabricated. A limit of detection of 150 nT is observed and excellent deformation stability is achieved after wrapping of the flexible sensor, with bending radii down to 5 mm. The flexible AMR sensor is used to read a magnetic pattern with a thickness of 10 μm that is formed by ferrite magnetic inks. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Huge tunnelling anisotropic magnetoresistance in (Ga,Mn)As nanoconstrictions

    Czech Academy of Sciences Publication Activity Database

    Giddings, A.D.; Makarovsky, O. N.; Khalid, M.N.; Yasin, S.; Edmonds, K. W.; Campion, R. P.; Wunderlich, J.; Jungwirth, Tomáš; Williams, D.A.; Gallagher, B. L.; Foxon, C. T.

    2008-01-01

    Roč. 10, č. 8 (2008), 085004/1-085004/9 ISSN 1367-2630 R&D Projects: GA ČR GEFON/06/E002; GA MŠk LC510; GA ČR GA202/05/0575; GA ČR GA202/04/1519 EU Projects: European Commission(XE) 015728 - NANOSPIN Institutional research plan: CEZ:AV0Z10100521 Keywords : ferromagnetic semiconductor * nanoconstriction * tunneling anisotropic magnetoresistance , Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.440, year: 2008

  12. Anisotropic cell growth-regulated surface micropatterns in flower petals

    Directory of Open Access Journals (Sweden)

    Xiao Huang

    2017-05-01

    Full Text Available Flower petals have not only diverse macroscopic morphologies but are rich in microscopic surface patterns, which are crucial to their biological functions. Both experimental measurements and theoretical analysis are conducted to reveal the physical mechanisms underlying the formation of minute wrinkles on flower petals. Three representative flowers, daisy, kalanchoe blossfeldiana, and Eustoma grandiflorum, are investigated as examples. A surface wrinkling model, incorporating the measured mechanical properties and growth ratio, is used to elucidate the difference in their surface morphologies. The mismatch between the anisotropic epidermal cell growth and the isotropic secretion of surficial wax is found to dictate the surface patterns.

  13. Scheme for achieving coherent perfect absorption by anisotropic metamaterials

    KAUST Repository

    Zhang, Xiujuan

    2017-02-22

    We propose a unified scheme to achieve coherent perfect absorption of electromagnetic waves by anisotropic metamaterials. The scheme describes the condition on perfect absorption and offers an inverse design route based on effective medium theory in conjunction with retrieval method to determine practical metamaterial absorbers. The scheme is scalable to frequencies and applicable to various incident angles. Numerical simulations show that perfect absorption is achieved in the designed absorbers over a wide range of incident angles, verifying the scheme. By integrating these absorbers, we further propose an absorber to absorb energy from two coherent point sources.

  14. Strain effects on anisotropic magnetoresistance in a nanowire spin valve

    Science.gov (United States)

    Hossain, Md I.; Maksud, M.; Subramanian, A.; Atulasimha, J.; Bandyopadhyay, S.

    2016-11-01

    The longitudinal magnetoresistance of a copper nanowire contacted by two cobalt contacts shows broad spin-valve peaks at room temperature. However, when the contacts are slightly heated, the peaks change into troughs which are signature of anisotropic magnetoresistance (AMR). Under heating, the differential thermal expansion of the contacts and the substrate generates a small strain in the cobalt contacts which enhances the AMR effect sufficiently to change the peak into a trough. This shows the extreme sensitivity of AMR to strain. The change in the AMR resistivity coefficient due to strain is estimated to be a few m Ω -m/microstrain.

  15. Quantum walks with an anisotropic coin I: spectral theory

    Science.gov (United States)

    Richard, S.; Suzuki, A.; Tiedra de Aldecoa, R.

    2018-02-01

    We perform the spectral analysis of the evolution operator U of quantum walks with an anisotropic coin, which include one-defect models, two-phase quantum walks, and topological phase quantum walks as special cases. In particular, we determine the essential spectrum of U, we show the existence of locally U-smooth operators, we prove the discreteness of the eigenvalues of U outside the thresholds, and we prove the absence of singular continuous spectrum for U. Our analysis is based on new commutator methods for unitary operators in a two-Hilbert spaces setting, which are of independent interest.

  16. Anisotropic mass density by two-dimensional acoustic metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Torrent, Daniel; Sanchez-Dehesa, Jose [Wave Phenomena Group, Department of Electronic Engineering, Polytechnic University of Valencia, C/Camino de Vera s/n, E-46022 Valencia (Spain)], E-mail: jsdehesa@upvnet.upv.es

    2008-02-15

    We show that specially designed two-dimensional arrangements of full elastic cylinders embedded in a nonviscous fluid or gas define (in the homogenization limit) a new class of acoustic metamaterials characterized by a dynamical effective mass density that is anisotropic. Here, analytic expressions for the dynamical mass density and the effective sound velocity tensors are derived in the long wavelength limit. Both show an explicit dependence on the lattice filling fraction, the elastic properties of cylinders relative to the background, their positions in the unit cell, and their multiple scattering interactions. Several examples of these metamaterials are reported and discussed.

  17. Anisotropic parameter inversion in VTI media using diffraction data

    KAUST Repository

    Waheed, Umair bin

    2013-09-22

    Diffracted waves contain useful information regarding the subsurface geometry and velocity. They are particularly valuable for anisotropic media as they inherently possess a wide range of dips necessary to resolve angular dependence of velocity. Using this property of diffraction data to our vantage, we develop an algorithm to invert for effective η model, assuming no prior knowledge of it. The obtained effective η model is then converted to interval η model using Dix-type inversion formula. The effectiveness of this approach is tested on the VTI Marmousi model, which yields good structural match even for a highly complex media such as the Marmousi model.

  18. On the lamb wave propagation in anisotropic laminated composite plates

    International Nuclear Information System (INIS)

    Park, Soo Keun; Jeong, Hyun Jo; Kim, Moon Saeng

    1998-01-01

    This paper examines the propagation of Lamb (or plate) waves in anisotropic laminated composite plates. The dispersion relations are explicitly derived using the classical plate theory (CLT), the first-order shear deformation theory (FSDT) and the exact solution (ES), Attention is paid to the lowest antisymmetric (flexural) and lowest symmetric(extensional) modes in the low frequency, long wavelength limit. Different values of shear correction factor were tested in FSDT and comparisons between flexural wave dispersion curves were made with exact results to asses the range of validity of approximate plate theories in the frequency domain.

  19. Aeroelastic modal dynamics of wind turbines including anisotropic effects

    Energy Technology Data Exchange (ETDEWEB)

    Fisker Skjoldan, P.

    2011-03-15

    Several methods for aeroelastic modal analysis of a rotating wind turbine are developed and used to analyse the modal dynamics of two simplified models and a complex model in isotropic and anisotropic conditions. The Coleman transformation is used to enable extraction of the modal frequencies, damping, and periodic mode shapes of a rotating wind turbine by describing the rotor degrees of freedom in the inertial frame. This approach is valid only for an isotropic system. Anisotropic systems, e.g., with an unbalanced rotor or operating in wind shear, are treated with the general approaches of Floquet analysis or Hill's method which do not provide a unique reference frame for observing the modal frequency, to which any multiple of the rotor speed can be added. This indeterminacy is resolved by requiring that the periodic mode shape be as constant as possible in the inertial frame. The modal frequency is thus identified as the dominant frequency in the response of a pure excitation of the mode observed in the inertial frame. A modal analysis tool based directly on the complex aeroelastic wind turbine code BHawC is presented. It uses the Coleman approach in isotropic conditions and the computationally efficient implicit Floquet analysis in anisotropic conditions. The tool is validated against system identifications with the partial Floquet method on the nonlinear BHawC model of a 2.3 MW wind turbine. System identification results show that nonlinear effects on the 2.3 MW turbine in most cases are small, but indicate that the controller creates nonlinear damping. In isotropic conditions the periodic mode shape contains up to three harmonic components, but in anisotropic conditions it can contain an infinite number of harmonic components with frequencies that are multiples of the rotor speed. These harmonics appear in calculated frequency responses of the turbine. Extreme wind shear changes the modal damping when the flow is separated due to an interaction between

  20. Anisotropic Expansion of a Thermal Dipolar Bose Gas.

    Science.gov (United States)

    Tang, Y; Sykes, A G; Burdick, N Q; DiSciacca, J M; Petrov, D S; Lev, B L

    2016-10-07

    We report on the anisotropic expansion of ultracold bosonic dysprosium gases at temperatures above quantum degeneracy and develop a quantitative theory to describe this behavior. The theory expresses the postexpansion aspect ratio in terms of temperature and microscopic collisional properties by incorporating Hartree-Fock mean-field interactions, hydrodynamic effects, and Bose-enhancement factors. Our results extend the utility of expansion imaging by providing accurate thermometry for dipolar thermal Bose gases. Furthermore, we present a simple method to determine scattering lengths in dipolar gases, including near a Feshbach resonance, through observation of thermal gas expansion.

  1. Quantum magnets with anisotropic infinite range random interactions.

    Science.gov (United States)

    Arrachea, Liliana; Rozenberg, Marcelo J

    2005-04-01

    Using exact diagonalization techniques, we study the dynamical response of the anisotropic disordered Heisenberg model for systems of S=1/2 spins with infinite range random exchange interactions at temperature T=0. The model can be considered as a generalization, to the quantum case, of the well-known Sherrington-Kirkpatrick classical spin glass model. We also compute and study the behavior of the Edwards Anderson order parameter and energy per spin as the anisotropy evolves from the Ising to the Heisenberg limits.

  2. Predicting anisotropic thermal displacements for hydrogens from solid-state NMR: a study on hydrogen bonding in polymorphs of palmitic acid.

    Science.gov (United States)

    Wang, Luther; Uribe-Romo, Fernando J; Mueller, Leonard J; Harper, James K

    2018-03-28

    The hydrogen-bonding environments at the COOH moiety in eight polycrystalline polymorphs of palmitic acid are explored using solid-state NMR. Although most phases have no previously reported crystal structure, measured 13C chemical shift tensors for COOH moieties, combined with DFT modeling establish that all phases crystallize with a cyclic dimer (R22(8)) hydrogen bonding arrangement. Phases A2, Bm and Em have localized OH hydrogens while phase C has a dynamically disordered OH hydrogen. The phase designated As is a mix of five forms, including 27.4% of Bm and four novel phases not fully characterized here due to insufficient sample mass. For phases A2, Bm, Em, and C the anisotropic uncertainties in the COOH hydrogen atom positions are established using a Monte Carlo sampling scheme. Sampled points are retained or rejected at the ±1σ level based upon agreement of DFT computed 13COOH tensors with experimental values. The collection of retained hydrogen positions bear a remarkable resemblance to the anisotropic displacement parameters (i.e. thermal ellipsoids) from diffraction studies. We posit that this similarity is no mere coincidence and that the two are fundamentally related. The volumes of NMR-derived anisotropic displacement ellipsoids for phases with localized OH hydrogens are 4.1 times smaller than those derived from single crystal X-ray diffraction and 1.8 times smaller than the volume of benchmark single crystal neutron diffraction values.

  3. Mixed plastics recycling technology

    CERN Document Server

    Hegberg, Bruce

    1995-01-01

    Presents an overview of mixed plastics recycling technology. In addition, it characterizes mixed plastics wastes and describes collection methods, costs, and markets for reprocessed plastics products.

  4. Mixing and diffusion in intermittent overturning turbulence

    Science.gov (United States)

    Redondo, Jose M.; Mahjoub, Otman B.; Gonzalez-Nieto, Pilar L.; Lawry, Andrew

    2014-05-01

    of scales. The method involving the multi-fractal dimension measurements is much more elaborated and seems to have a better theoretical justification in the sense that it is possible that different concentrations showing different fractal dimensions may be due to different levels of intermittency (and thus different spectra, which are not generally in equilibrium as dscribed by[9,10]. Using topological descriptors we can establish now a theoretical baseline pattern for the turbulence behaviour that is reflected in the different structures (volume fraction, velocity, vorticity, helicity) we can thus obtain a classification relating D3 and the integral of the different fractal dimensions D2 for different levels of scalar (volume fraction reaction intensity or temperature). [5,8,11] Vorticity evolution is more smooth and quite different than that of volume fraction or density and these seem also different for the RT and RM instability driven mixing showing a wider range of even higher mixing efficiencies 0- 0.66 Thanks to European Union project ERBIC15-CT96-0111 Multi-scale complex fluid flows and interfacial phenomena (PITN-GA-2008-214919). ERCOFTAC and GenCat. grant 2001SGR00221. [1] Mahjoub O.B., Redondo J.M. and Babiano A. (2000) Hyerarchy flux in nonhomogeneous flows in Turbulent diffusion in the environment Eds. Redondo J.M. and Babiano A. 249-260. . [2] Dalziel, S. B.,(1994) Perturbations and coherent flow in Rayleigh-Taylor instability: in 4th International Workshop on the Physics of Compressible Turbulent Mixing, ed. P. F. Linden, D. L. Youngs, & S. B. Dalziel; 32-41. [3] Linden, P. F., Redondo, J. M., and Youngs, D. (1994) Molecular mixing in Rayleigh-Taylor instability, J. Fluid Mech. 265, 97-124 [4] Vindel, J.M., Yague, C. and Redondo, J.M. Nuovo Cimento (2008) 31, [5]Redondo J.M. (1993) Fractal models of density interfaces. Wavelets, Fractals and Fourier transforms. (Eds.) M. Farge, J.C.R. Hunt and J.C. Vassilicos. 353-370. IMA number 43, Clarendon Press

  5. Angular Control of a Hybrid Magnetic Metamolecule Using Anisotropic FeCo

    Science.gov (United States)

    Gregory, S. A.; Maple, L. C.; Stenning, G. B. G.; Hesjedal, T.; van der Laan, G.; Bowden, G. J.

    2015-11-01

    By coupling magnetic elements to metamaterials, hybrid metamolecules can be created with useful properties such as photon-magnon mode mixing. Here, we present results for a split-ring resonator (SRR) placed in close proximity to a thin crystalline film of magnetically hard FeCo. Eddy-current shielding is suppressed by patterning the FeCo into 100 -μ m disks. At the ferromagnetic resonance (FMR) condition of FeCo, photon-magnon coupling strengths of 5% are observed. Altogether, three distinct features are presented and discussed: (i) remanent magnets allow FMR to be performed in a near-zero field, partially eliminating the need for applied fields; (ii) the anisotropic FMR permits angular control over hybrid SRR and FMR resonances; and (iii) the in-plane and out-of-plane magnetization of FeCo opens the door to "magnetically configurable metamaterials" in real time. Finally, a special study is presented of how best to excite the numerous transverse magnetic and electric modes of the SRR by using near-field excitation from a coplanar waveguide.

  6. Anisotropic ferromagnetic polymer: A first step for their implementation in microfluidic systems

    Directory of Open Access Journals (Sweden)

    Damien Le Roy

    2016-05-01

    Full Text Available Here we report on the influence of anisotropic microstructure on the performances of magnetically soft micro-patterns intended to integrate microfluidic systems. These micro-patterns are made of a composite obtained by mixing carbonyl iron particles with polydimethylsiloxane, which offers practical integration advantages. We investigated a wide range of magnetic particle loadings, from 10wt% to 83wt%, reaching magnetization as high as 630 kA/m. A homogeneous field was applied during the polymer’s cross-linking phase so that to obtain a 1D arrangement of the particles in the solidified polymer, along the field direction. Here we present the results obtained for square-based micro-pillars prepared under a magnetic field applied along one of its diagonal. We assessed the magnetic anisotropy owing to the particles’ spatial arrangement by comparing the magnetization processes along the two diagonals of the micro-pillar’s base. The magnetic susceptibilities along the two directions differ from a factor greater than three. The results can be described in terms of high aspect ratio and porous magnetic agglomerates.

  7. Anisotropic behavior and complex colinear magnetic structures of cerium and actinide intermetallics

    International Nuclear Information System (INIS)

    Cooper, B.R.

    1977-01-01

    A review is given of the experimental situation and degree of theoretical understanding for the occurrence of complex colinear magnetic structures in cerium and actinide intermetallics of NaCl structure. In doing this, emphasis is on the qualitative nature of the anisotropic effects necessary to understand the behavior. With this in mind we focus on the I to IA magnetic structure transition, and indeed more simply, on the occurrence of the IA magnetic structure which appears for CeBi, UAs, and some of the mixed uranium monopnictide-monochalcogenides. We show how the experimental observations involving properties related to the IA magnetic structure indicate important qualitative features of the physical mechanism involved. Through discussion of the possible analogue to the situation in UO 2 , the idea is introduced that magnetoelastic effects involving internal rearrangement modes may play a key role in the occurrence of the IA structure. Internal rearrangement modes are modes where one ionic species remains at its site in the undistorted crystal structure, and the other species is displaced from its position in the undistorted structure. We show that in a very natural way one can anticipate the possible occurrence of an internal rearrangement mode having a four-layer, periodic displacement sequence for planes for one species in the NaCl structure crystals, while the other species remains undisplaced. The presence of such a static lattice mode is susceptible to direct experimental observation. (author)

  8. Anisotropic Friedel oscillations in a two-dimensional electron gas with a Rashba-Dresselhaus spin-orbit interaction

    Science.gov (United States)

    Kozlov, I. V.; Kolesnichenko, Yu. A.

    2017-07-01

    We present a theoretical study of the spatial distribution of the local density of states (LDOS) and the local magnetization density (LMD) in the vicinity of a magnetic point-defect in a degenerate two-dimensional electron gas with a mixed Rashba-Dresselhaus spin-orbit coupling interaction (SOI). The dependence of the Friedel oscillations, which arise under these conditions, on the ratio of the SOI constants is investigated. We obtain asymptotic expressions for the oscillatory parts of the LDOS and the LMD, that are accurate for large distances from the defect. It is shown, that the Friedel oscillations are significantly anisotropic and contain several harmonics for certain ratios of the SOI constants. Period of the oscillations for directions along the symmetry axes of the Fermi contours are determined. Finally, we introduce a method for determining the values of the two SOI constants by measuring the period of the Friedel oscillations of the LDOS and the LMD for different harmonics.

  9. The Promotion of the Efficiency of Organic Photovoltaic Devices by Addition of Anisotropic CdSe Nanocrystals

    Directory of Open Access Journals (Sweden)

    Shu-Ru Chung

    2014-01-01

    Full Text Available CdSe nanocrystals (NCs with different morphologies have been synthesized and applied as the acceptor in the active layer of the organic photovoltaic (OPV devices. CdSe tetrapod (TP/nanorod (NR with zinc-blended seeds and wurtzite arms is prepared by seed growth method and mixed with poly(3-hexylthiophene (P3HT: [6,6]-phenyl-C61-butyric acid methyl ester (PCBM. When the concentrations of CdSe in P3HT: PCBM system are 50 wt% optimally, the efficiency can be promoted about 4.3%, suggesting that an enhancement of 13.2% can be obtained and the addition of anisotropic CdSe NCs content in the active layer can be beneficial for the transport of electrons and light absorption in the OPV devices.

  10. Grad-Shafranov reconstruction of Earth's magnetopause with anisotropic pressure

    Science.gov (United States)

    Chen, G. W.; Hau, L. N.

    2016-12-01

    Grad-Shafranov (GS) reconstruction is a technique to analyze the two-dimensional (2-D) coherent field structures of thin current sheets and by using this method one can construct the 2-D predicted values in an optimal co-moving frame from the data measured by a single spacecraft (Hau and Sonnerup, 1999). In this study we have developed and benchmarked a new GS solver based on the modified, extended Grad-Shafranov equations for the ideal magnetohydrodynamic (MHD) model with anisotropic plasma pressure (Hau and Sonnerup, 1993; Hau, 2002; Sonnerup et al., 2006), and applied it to the magnetopause crossing events observed by THEMIS spacecraft. The new GS solver can give rise to the 2-D spatial information of perpendicular and parallel plasma pressures for various thermodynamic conditions described by a set of double polytropic energy laws. We also compare the results based on isotropic and anisotropic GS solvers to examine the effects of pressure anisotropy on the reconstructed 2-D magnetopause structure.

  11. Anisotropic gold nanoparticles: synthesis, properties, applications, and toxicity.

    Science.gov (United States)

    Li, Na; Zhao, Pengxiang; Astruc, Didier

    2014-02-10

    Anisotropic gold nanoparticles (AuNPs) have attracted the interest of scientists for over a century, but research in this field has considerably accelerated since 2000 with the synthesis of numerous 1D, 2D, and 3D shapes as well as hollow AuNP structures. The anisotropy of these nonspherical, hollow, and nanoshell AuNP structures is the source of the plasmon absorption in the visible region as well as in the near-infrared (NIR) region. This NIR absorption is especially sensitive to the AuNP shape and medium and can be shifted towards the part of the NIR region in which living tissue shows minimum absorption. This has led to crucial applications in medical diagnostics and therapy ("theranostics"), especially with Au nanoshells, nanorods, hollow nanospheres, and nanocubes. In addition, Au nanowires (AuNWs) can be synthesized with longitudinal dimensions of several tens of micrometers and can serve as plasmon waveguides for sophisticated optical devices. The application of anisotropic AuNPs has rapidly spread to optical, biomedical, and catalytic areas. In this Review, a brief historical survey is given, followed by a summary of the synthetic modes, variety of shapes, applications, and toxicity issues of this fast-growing class of nanomaterials. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Level Set Approach to Anisotropic Wet Etching of Silicon

    Directory of Open Access Journals (Sweden)

    Branislav Radjenović

    2010-05-01

    Full Text Available In this paper a methodology for the three dimensional (3D modeling and simulation of the profile evolution during anisotropic wet etching of silicon based on the level set method is presented. Etching rate anisotropy in silicon is modeled taking into account full silicon symmetry properties, by means of the interpolation technique using experimentally obtained values for the etching rates along thirteen principal and high index directions in KOH solutions. The resulting level set equations are solved using an open source implementation of the sparse field method (ITK library, developed in medical image processing community, extended for the case of non-convex Hamiltonians. Simulation results for some interesting initial 3D shapes, as well as some more practical examples illustrating anisotropic etching simulation in the presence of masks (simple square aperture mask, convex corner undercutting and convex corner compensation, formation of suspended structures are shown also. The obtained results show that level set method can be used as an effective tool for wet etching process modeling, and that is a viable alternative to the Cellular Automata method which now prevails in the simulations of the wet etching process.

  13. Spin interferometry in anisotropic spin-orbit fields

    Science.gov (United States)

    Saarikoski, Henri; Reynoso, Andres A.; Baltanás, José Pablo; Frustaglia, Diego; Nitta, Junsaku

    2018-03-01

    Electron spins in a two-dimensional electron gas can be manipulated by spin-orbit (SO) fields originating from either Rashba or Dresselhaus interactions with independent isotropic characteristics. Together, though, they produce anisotropic SO fields with consequences on quantum transport through spin interference. Here we study the transport properties of modeled mesoscopic rings subject to Rashba and Dresselhaus [001] SO couplings in the presence of an additional in-plane Zeeman field acting as a probe. By means of one- and two-dimensional quantum transport simulations we show that this setting presents anisotropies in the quantum resistance as a function of the Zeeman field direction. Moreover, the anisotropic resistance can be tuned by the Rashba strength up to the point to invert its response to the Zeeman field. We also find that a topological transition in the field texture that is associated with a geometric phase switching is imprinted in the anisotropy pattern. We conclude that resistance anisotropy measurements can reveal signatures of SO textures and geometric phases in spin carriers.

  14. Cellular Scale Anisotropic Topography Guides Schwann Cell Motility

    Science.gov (United States)

    Mitchel, Jennifer A.; Hoffman-Kim, Diane

    2011-01-01

    Directed migration of Schwann cells (SC) is critical for development and repair of the peripheral nervous system. Understanding aspects of motility specific to SC, along with SC response to engineered biomaterials, may inform strategies to enhance nerve regeneration. Rat SC were cultured on laminin-coated microgrooved poly(dimethyl siloxane) platforms that were flat or presented repeating cellular scale anisotropic topographical cues, 30 or 60 µm in width, and observed with timelapse microscopy. SC motion was directed parallel to the long axis of the topography on both the groove floor and the plateau, with accompanying differences in velocity and directional persistence in comparison to SC motion on flat substrates. In addition, feature dimension affected SC morphology, alignment, and directional persistence. Plateaus and groove floors presented distinct cues which promoted differential motility and variable interaction with the topographical features. SC on the plateau surfaces tended to have persistent interactions with the edge topography, while SC on the groove floors tended to have infrequent contact with the corners and walls. Our observations suggest the capacity of SC to be guided without continuous contact with a topographical cue. SC exhibited a range of distinct motile morphologies, characterized by their symmetry and number of extensions. Across all conditions, SC with a single extension traveled significantly faster than cells with more or no extensions. We conclude that SC motility is complex, where persistent motion requires cellular asymmetry, and that anisotropic topography with cellular scale features can direct SC motility. PMID:21949703

  15. An efficient wave extrapolation method for anisotropic media with tilt

    KAUST Repository

    Waheed, Umair bin

    2015-03-23

    Wavefield extrapolation operators for elliptically anisotropic media offer significant cost reduction compared with that for the transversely isotropic case, particularly when the axis of symmetry exhibits tilt (from the vertical). However, elliptical anisotropy does not provide accurate wavefield representation or imaging for transversely isotropic media. Therefore, we propose effective elliptically anisotropic models that correctly capture the kinematic behaviour of wavefields for transversely isotropic media. Specifically, we compute source-dependent effective velocities for the elliptic medium using kinematic high-frequency representation of the transversely isotropic wavefield. The effective model allows us to use cheaper elliptic wave extrapolation operators. Despite the fact that the effective models are obtained by matching kinematics using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy trade-off for wavefield computations in transversely isotropic media, particularly for media of low to moderate complexity. In addition, the wavefield solution is free from shear-wave artefacts as opposed to the conventional finite-difference-based transversely isotropic wave extrapolation scheme. We demonstrate these assertions through numerical tests on synthetic tilted transversely isotropic models.

  16. Magnetic anisotropy and anisotropic ballistic conductance of thin magnetic wires

    International Nuclear Information System (INIS)

    Sabirianov, R.

    2006-01-01

    The magnetocrystalline anisotropy of thin magnetic wires of iron and cobalt is quite different from the bulk phases. The spin moment of monatomic Fe wire may be as high as 3.4 μ B , while the orbital moment as high as 0.5 μ B . The magnetocrystalline anisotropy energy (MAE) was calculated for wires up to 0.6 nm in diameter starting from monatomic wire and adding consecutive shells for thicker wires. I observe that Fe wires exhibit the change sign with the stress applied along the wire. It means that easy axis may change from the direction along the wire to perpendicular to the wire. We find that ballistic conductance of the wire depends on the direction of the applied magnetic field, i.e. shows anisotropic ballistic magnetoresistance. This effect occurs due to the symmetry dependence of the splitting of degenerate bands in the applied field which changes the number of bands crossing the Fermi level. We find that the ballistic conductance changes with applied stress. Even for thicker wires the ballistic conductance changes by factor 2 on moderate tensile stain in our 5x4 model wire. Thus, the ballistic conductance of magnetic wires changes in the applied field due to the magnetostriction. This effect can be observed as large anisotropic BMR in the experiment

  17. Numerical simulation of ultrasonic wave propagation in elastically anisotropic media

    International Nuclear Information System (INIS)

    Jacob, Victoria Cristina Cheade; Jospin, Reinaldo Jacques; Bittencourt, Marcelo de Siqueira Queiroz

    2013-01-01

    The ultrasonic non-destructive testing of components may encounter considerable difficulties to interpret some inspections results mainly in anisotropic crystalline structures. A numerical method for the simulation of elastic wave propagation in homogeneous elastically anisotropic media, based on the general finite element approach, is used to help this interpretation. The successful modeling of elastic field associated with NDE is based on the generation of a realistic pulsed ultrasonic wave, which is launched from a piezoelectric transducer into the material under inspection. The values of elastic constants are great interest information that provide the application of equations analytical models, until small and medium complexity problems through programs of numerical analysis as finite elements and/or boundary elements. The aim of this work is the comparison between the results of numerical solution of an ultrasonic wave, which is obtained from transient excitation pulse that can be specified by either force or displacement variation across the aperture of the transducer, and the results obtained from a experiment that was realized in an aluminum block in the IEN Ultrasonic Laboratory. The wave propagation can be simulated using all the characteristics of the material used in the experiment valuation associated to boundary conditions and from these results, the comparison can be made. (author)

  18. Oscillating electromagnetic soliton in an anisotropic ferromagnetic medium

    Energy Technology Data Exchange (ETDEWEB)

    Sathishkumar, P., E-mail: perumal_sathish@yahoo.co.in [Department of Physics, K.S.R. College of Engineering (Autonomous), Tiruchengode 637215, Tamilnadu (India); Senjudarvannan, R. [Department of Physics, Jansons Institute of Technology, Karumathampatty, Coimbatore 641659 (India)

    2017-05-01

    We investigate theoretically the propagation of electromagnetic oscillating soliton in the form of breather in an anisotropic ferromagnetic medium. The interaction of magnetization with the magnetic field component of the electromagnetic (EM) wave has been studied by solving Maxwell's equations coupled with a Landau–Lifshitz equation for the magnetization of the medium. We made a small perturbation on the magnetization and magnetic field along the direction of propagation of EM wave in the framework of reductive perturbation method and the associated nonlinear magnetization dynamics is governed by a generalized derivative nonlinear Schrödinger (DNLS) equation. In order to understand the dynamics of the concerned system, we employ the Jacobi elliptic function method to solve the DNLS equation and deduce breatherlike soliton modes for the EM wave in the medium. - Highlights: • The propagation of electromagnetic oscillating soliton in an anisotropic ferromagnetic medium is investigated in the presence of varying external magnetic field. • The magnetization and electromagnetic wave modulates in the form of breathing like oscillating solitons. • The governing nonlinear spin dynamical equation is studied through a reductive perturbation method. • The magnetization components of the ferromagnetic medium are derived using Jacobi elliptic functions method with the aid of symbolic computation.

  19. The structure and dynamics of polymer nanocomposites containing anisotropic nanoparticles

    Science.gov (United States)

    Lin, Chia-Chun; Ohno, Kohji; Clarke, Nigel; Winey, Karen; Composto, Russell; Hore, Michael

    2014-03-01

    The tracer diffusion of deuterated polystyrene (dPS; 49-532 kg/mol) is measured in polystyrene (PS: 270 kg/mol) nanocomposites containing PS-grafted (132 kg/mol) anisotropic nanoparticles (NP). The NP's are small aggregates containing iron oxide spheres (5nm). These NP's uniformly disperse in PS up to 100% loading. The structure of the polymer nanocomposites is probed using (ultra)small angle x-ray scattering (USAXS,SAXS). Peaks shift to high Q region with increasing NP loadings, indicating a decrease in spacing between particles. The interparticle distance for the pure NP case is 30nm, consistent with TEM, and a brush thickness of 15nm. The brush profile is also measured using SANS. The reduced tracer diffusion coefficient initially decreases as NP loadings increase and then reaches a minimum (35% reduction) near 0.25 vol% (core) for all dPS. With a further increase in NP loading, diffusion recovers to 90% of the unfilled case. Penetration of the tracer (i.e., wetting) into the brush will affect the effective interparticle distance. Diffusion of dPS (1866 kg/mol) will be examined to determine if the dry brush case influences the recovery at high loading. These experiments demonstrate that polymer brushes grafted to anisotropic nano particles can affect the tracer diffusion pathway and indicate that diffusion models should incorporate the interfacial structure between brush and matrix.

  20. An anisotropic hydrogel with electrostatic repulsion between cofacially aligned nanosheets

    Science.gov (United States)

    Liu, Mingjie; Ishida, Yasuhiro; Ebina, Yasuo; Sasaki, Takayoshi; Hikima, Takaaki; Takata, Masaki; Aida, Takuzo

    2015-01-01

    Machine technology frequently puts magnetic or electrostatic repulsive forces to practical use, as in maglev trains, vehicle suspensions or non-contact bearings. In contrast, materials design overwhelmingly focuses on attractive interactions, such as in the many advanced polymer-based composites, where inorganic fillers interact with a polymer matrix to improve mechanical properties. However, articular cartilage strikingly illustrates how electrostatic repulsion can be harnessed to achieve unparalleled functional efficiency: it permits virtually frictionless mechanical motion within joints, even under high compression. Here we describe a composite hydrogel with anisotropic mechanical properties dominated by electrostatic repulsion between negatively charged unilamellar titanate nanosheets embedded within it. Crucial to the behaviour of this hydrogel is the serendipitous discovery of cofacial nanosheet alignment in aqueous colloidal dispersions subjected to a strong magnetic field, which maximizes electrostatic repulsion and thereby induces a quasi-crystalline structural ordering over macroscopic length scales and with uniformly large face-to-face nanosheet separation. We fix this transiently induced structural order by transforming the dispersion into a hydrogel using light-triggered in situ vinyl polymerization. The resultant hydrogel, containing charged inorganic structures that align cofacially in a magnetic flux, deforms easily under shear forces applied parallel to the embedded nanosheets yet resists compressive forces applied orthogonally. We anticipate that the concept of embedding anisotropic repulsive electrostatics within a composite material, inspired by articular cartilage, will open up new possibilities for developing soft materials with unusual functions.

  1. Membrane-mediated interaction between strongly anisotropic protein scaffolds.

    Directory of Open Access Journals (Sweden)

    Yonatan Schweitzer

    2015-02-01

    Full Text Available Specialized proteins serve as scaffolds sculpting strongly curved membranes of intracellular organelles. Effective membrane shaping requires segregation of these proteins into domains and is, therefore, critically dependent on the protein-protein interaction. Interactions mediated by membrane elastic deformations have been extensively analyzed within approximations of large inter-protein distances, small extents of the protein-mediated membrane bending and small deviations of the protein shapes from isotropic spherical segments. At the same time, important classes of the realistic membrane-shaping proteins have strongly elongated shapes with large and highly anisotropic curvature. Here we investigated, computationally, the membrane mediated interaction between proteins or protein oligomers representing membrane scaffolds with strongly anisotropic curvature, and addressed, quantitatively, a specific case of the scaffold geometrical parameters characterizing BAR domains, which are crucial for membrane shaping in endocytosis. In addition to the previously analyzed contributions to the interaction, we considered a repulsive force stemming from the entropy of the scaffold orientation. We computed this interaction to be of the same order of magnitude as the well-known attractive force related to the entropy of membrane undulations. We demonstrated the scaffold shape anisotropy to cause a mutual aligning of the scaffolds and to generate a strong attractive interaction bringing the scaffolds close to each other to equilibrium distances much smaller than the scaffold size. We computed the energy of interaction between scaffolds of a realistic geometry to constitute tens of kBT, which guarantees a robust segregation of the scaffolds into domains.

  2. Anisotropic capillary wave propagation in a ripple tank

    Science.gov (United States)

    Velazquez, Daniel; Crowder, Daniel; Linville, Jon; Wilson, Thomas

    2007-10-01

    A preliminary study has been undertaken to demonstrate the anisotropic wave propagation of capillary waves in a water ripple tank. We have fabricated, using a computer-controlled milling machine, a contoured surface upon a 12'' square, .5ex1-.1em/ -.15em.25ex2 '' thick Plexiglas plate with gradually deepened (˜4 mm) angular channels emanating from the center of the plate and spaced every ninety degrees, with an additional cylindrical well in the plate's center, to accept the vibrating ball of the wave generator. The plate is submerged in the ripple tank, with the cylindrical well aligned with the point source (ball), and the water level adjusted such that the minimum and maximum water depths are 2 and 6 mm respectively and resulting wavefronts have been photographed. Provided the difference between the minimum and maximum of the phase velocities (˜17, 23 cm/s) for the corresponding depths (2 and 6 mm) of the capillary waves, can be made appropriately large (˜25%) at a fixed frequency (˜5 Hz), then one would expect to observe interesting folds (`caustics') in the wavefront in the directions of largest phase velocity (along the channels), corresponding to zero-curvature inflection points in the slowness surface. (See J.P. Wolfe ``Phonon Imaging'' (Cambridge University Press, 1998)). We have observed anisotropic wavefronts but as yet, no evidence for the expected folds.

  3. Anisotropic Thermal Behavior of Silicone Polymer, DC 745

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Jillian Cathleen [Univ. of Oregon, Eugene, OR (United States). Dept. of Chemistry; Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Torres, Joseph Angelo [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Volz, Heather Michelle [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gallegos, Jennifer Marie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Yang, Dali [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-09-02

    In material applications, it is important to understand how polymeric materials behave in the various environments they may encounter. One factor governing polymer behavior is processing history. Differences in fabrication will result in parts with varied or even unintended properties. In this work, the thermal expansion behavior of silicone DC 745 is studied. Thermomechanical analysis (TMA) is used to determine changes in sample dimension resulting from changes in temperature. This technique can measure thermal events such as the linear coefficient of thermal expansion (CTE), melting, glass transitions, cure shrinkage, and internal relaxations. Using a thermomechanical analyzer (Q400 TMA), it is determined that DC 745 expands anisotropically when heated. This means that the material has a different CTE depending upon which direction is being measured. In this study, TMA experiments were designed in order to confirm anisotropic thermal behavior in multiple DC 745 samples of various ages and lots. TMA parameters such as temperature ramp rate, preload force, and temperature range were optimized in order to ensure the most accurate and useful data. A better understanding of the thermal expansion of DC 745 will allow for more accurate modeling of systems using this material.

  4. Anisotropic toughness and strength in graphene and its atomistic origin

    Science.gov (United States)

    Hossain, M. Zubaer; Ahmed, Tousif; Silverman, Benjamin; Khawaja, M. Shehroz; Calderon, Justice; Rutten, Andrew; Tse, Stanley

    2018-01-01

    This paper presents the implication of crystallographic orientation on toughness and ideal strength in graphene under lattice symmetry-preserving and symmetry-breaking deformations. In symmetry-preserving deformation, both toughness and strength are isotropic, regardless of the chirality of the lattice; whereas, in symmetry-breaking deformation they are strongly anisotropic, even in the presence of vacancy defects. The maximum and minimum of toughness or strength occur for loading along the zigzag direction and the armchair direction, respectively. The anisotropic behavior is governed by a complex interplay among bond-stretching deformation, bond-bending deformation, and the chirality of the lattice. Nevertheless, the condition for crack-nucleation is dictated by the maximum bond-force required for bond rupture, and it is independent of the chiral angle of the lattice or loading direction. At the onset of crack-nucleation a localized nucleation zone is formed, wherein the bonds rupture locally satisfying the maximum bond-force criterion. The nucleation zone acts as the physical origin in triggering the fracture nucleation process, but its presence is undetectable from the macroscopic stress-strain data.

  5. Current-induced switching in transport through anisotropic magnetic molecules

    Science.gov (United States)

    Bode, Niels; Arrachea, Liliana; Lozano, Gustavo S.; Nunner, Tamara S.; von Oppen, Felix

    2012-03-01

    Anisotropic single-molecule magnets may be thought of as molecular switches, with possible applications to molecular spintronics. In this paper, we consider current-induced switching in single-molecule junctions containing an anisotropic magnetic molecule. We assume that the carriers interact with the magnetic molecule through the exchange interaction and focus on the regime of high currents in which the molecular spin dynamics is slow compared to the time which the electrons spend on the molecule. In this limit, the molecular spin obeys a nonequilibrium Langevin equation which takes the form of a generalized Landau-Lifshitz-Gilbert equation and which we derive microscopically by means of a nonequilibrium Born-Oppenheimer approximation. We exploit this Langevin equation to identify the relevant switching mechanisms and to derive the current-induced switching rates. As a by-product, we also derive S-matrix expressions for the various torques entering into the Landau-Lifshitz-Gilbert equation which generalize previous expressions in the literature to nonequilibrium situations.

  6. On spectral scaling laws for incompressible anisotropic magnetohydrodynamic turbulence

    International Nuclear Information System (INIS)

    Galtier, Sebastien; Pouquet, Annick; Mangeney, Andre

    2005-01-01

    A heuristic model is given for anisotropic magnetohydrodynamics turbulence in the presence of a uniform external magnetic field B 0 e parallel . The model is valid for both moderate and strong B 0 and is able to describe both the strong and weak wave turbulence regimes as well as the transition between them. The main ingredient of the model is the assumption of constant ratio at all scales between the linear wave period and the nonlinear turnover time scale. Contrary to the model of critical balance introduced by Goldreich and Sridhar [Astrophys. J. 438, 763 (1995)], it is not assumed, in addition, that this ratio be equal to unity at all scales. This allows us to make use of the Iroshnikov-Kraichnan phenomenology; it is then possible to recover the widely observed anisotropic scaling law k parallel ∝k perpendicular 2/3 between parallel and perpendicular wave numbers (with reference to B 0 e parallel and to obtain for the total-energy spectrum E(k perpendicular ,k parallel )∼k perpendicular -α k parallel -β the universal prediction, 3α+2β=7. In particular, with such a prediction, the weak Alfven wave turbulence constant-flux solution is recovered and, for the first time, a possible explanation to its precursor found numerically by Galtier et al. [J. Plasma Phys. 63, 447 (2000)] is given.

  7. Slab albedo for linearly and quadratically anisotropic scattering kernel with modified F{sub N} method

    Energy Technology Data Exchange (ETDEWEB)

    Tuereci, R. Goekhan [Kirikkale Univ. (Turkey). Kirikkale Vocational School; Tuereci, D. [Ministry of Education, Ankara (Turkey). 75th year Anatolia High School

    2017-11-15

    One speed, time independent and homogeneous medium neutron transport equation is solved with the anisotropic scattering which includes both the linearly and the quadratically anisotropic scattering kernel. Having written Case's eigenfunctions and the orthogonality relations among of these eigenfunctions, slab albedo problem is investigated as numerically by using Modified F{sub N} method. Selected numerical results are presented in tables.

  8. Polarisations of quasi-waves in a general anisotropic porous solid ...

    Indian Academy of Sciences (India)

    Wave propagation is studied in a general anisotropic poroelastic solid saturated with a viscous fluid flowing through its pores of anisotropic permeability. The extended version of Biot's theory is used to derive a system of modified Christoffel equations for the propagation of plane harmonic waves in such media.

  9. A magnetic relaxation study on anisotropic reorientation in aqueous polyelectrolyte solutions

    International Nuclear Information System (INIS)

    Mulder, C.W.R.

    1984-01-01

    The present thesis proposes a study on anisotropic reorientation of aqueous polyelectrolyte solutions. In particular, it is directed to the question to what extent information may be obtained on anisotropic reorientation by nuclear magnetic relaxation experiments. The polymethacrylic acid/water system has been chosen as probe system. (Auth.)

  10. Odd number of coupled antiferromagnetic anisotropic Heisenberg chains: Spin wave theory

    International Nuclear Information System (INIS)

    Benyoussef, A.

    1996-10-01

    The effect of the chain and perpendicular anisotropies on the energy gap for odd number of coupled quantum spin-1/2 antiferromagnetic anisotropic Heisenberg chains is investigated using a spin wave theory. The energy gap opens above a critical anisotropic value. The known results of the isotropic case have been obtained. (author). 11 refs, 4 figs

  11. Genetic algorithm-based design method for multilevel anisotropic diffraction gratings

    Science.gov (United States)

    Okamoto, Hiroyuki; Noda, Kohei; Sakamoto, Moritsugu; Sasaki, Tomoyuki; Wada, Yasuhiro; Kawatsuki, Nobuhiro; Ono, Hiroshi

    2017-08-01

    We developed a method for the design of multilevel anisotropic diffraction gratings based on a genetic algorithm. The method is used to design the multilevel anisotropic diffraction gratings based on input data that represent the output from the required grating. The validity of the proposed method was evaluated by designing a multilevel anisotropic diffraction grating using the outputs from an orthogonal circular polarization grating. The design results corresponded to the orthogonal circular polarization grating structures that were used to provide outputs to act as the input data for the process. Comparison with existing design methods shows that the proposed method can reduce the number of human processes that are required to design multilevel anisotropic diffraction gratings. Additionally, the method will be able to design complex structures without any requirement for subsequent examination by a human designer. The method can contribute to the development of optical elements by designing multilevel anisotropic diffraction gratings.

  12. An In-Depth Tutorial on Constitutive Equations for Elastic Anisotropic Materials

    Science.gov (United States)

    Nemeth, Michael P.

    2011-01-01

    An in-depth tutorial on the constitutive equations for elastic, anisotropic materials is presented. Basic concepts are introduced that are used to characterize materials, and notions about how anisotropic material deform are presented. Hooke s law and the Duhamel-Neuman law for isotropic materials are presented and discussed. Then, the most general form of Hooke s law for elastic anisotropic materials is presented and symmetry requirements are given. A similar presentation is also given for the generalized Duhamel-Neuman law for elastic, anisotropic materials that includes thermal effects. Transformation equations for stress and strains are presented and the most general form of the transformation equations for the constitutive matrices are given. Then, specialized transformation equations are presented for dextral rotations about the coordinate axes. Next, concepts of material symmetry are introduced and criteria for material symmetries are presented. Additionally, engineering constants of fully anisotropic, elastic materials are derived from first principles and the specialized to several cases of practical importance.

  13. Continuous mixing of solids

    NARCIS (Netherlands)

    Raouf, M.S.

    1963-01-01

    The most important literature on theoretical aspects of mixing solids was reviewed.

    Only when the mixed materials showed no segregation it was possible to analyse the mixing process quantitatively. In this case the mixture could be described by the 'χ' Square test. Longitudinal mixing could be

  14. Electrical impedance tomography in anisotropic media with known eigenvectors

    Science.gov (United States)

    Abascal, Juan-Felipe P. J.; Lionheart, William R. B.; Arridge, Simon R.; Schweiger, Martin; Atkinson, David; Holder, David S.

    2011-06-01

    Electrical impedance tomography is an imaging method, with which volumetric images of conductivity are produced by injecting electrical current and measuring boundary voltages. It has the potential to become a portable non-invasive medical imaging technique. Until now, most implementations have neglected anisotropy even though human tissues like bone, muscle and brain white matter are markedly anisotropic. The recovery of an anisotropic conductivity tensor is uniquely determined by boundary measurements only up to a diffeomorphism that fixes the boundary. Nevertheless, uniqueness can be restored by providing information about the diffeomorphism. There are uniqueness results for two constraints: one eigenvalue and a multiple scalar of a general tensor. A useable constraint for medical applications is when the eigenvectors of the underlying tissue are known, which can be approximated from MRI or estimated from DT-MRI, although the eigenvalues are unknown. However there is no known theoretical result guaranteeing uniqueness for this constraint. In fact, only a few previous inversion studies have attempted to recover one or more eigenvalues assuming certain symmetries while ignoring nonuniqueness. In this work, the aim was to undertake a numerical study of the feasibility of the recovery of a piecewise linear finite element conductivity tensor in anisotropic media with known eigenvectors from the complete boundary data. The work suggests that uniqueness holds for this constraint, in addition to proposing a methodology for the incorporation of this prior for general conductivity tensors. This was carried out by performing an analysis of the Jacobian rank and by reconstructing four conductivity distributions: two diagonal tensors whose eigenvalues were linear and sinusoidal functions, and two general tensors whose eigenvectors resembled physiological tissue, one with eigenvectors spherically orientated like a spherical layered structure, and a sample of DT-MRI data of

  15. Anisotropic Behaviour of Magnetic Power Spectra in Solar Wind Turbulence.

    Science.gov (United States)

    Banerjee, S.; Saur, J.; Gerick, F.; von Papen, M.

    2017-12-01

    Introduction:High altitude fast solar wind turbulence (SWT) shows different spectral properties as a function of the angle between the flow direction and the scale dependent mean magnetic field (Horbury et al., PRL, 2008). The average magnetic power contained in the near perpendicular direction (80º-90º) was found to be approximately 5 times larger than the average power in the parallel direction (0º- 10º). In addition, the parallel power spectra was found to give a steeper (-2) power law than the perpendicular power spectral density (PSD) which followed a near Kolmogorov slope (-5/3). Similar anisotropic behaviour has also been observed (Chen et al., MNRAS, 2011) for slow solar wind (SSW), but using a different method exploiting multi-spacecraft data of Cluster. Purpose:In the current study, using Ulysses data, we investigate (i) the anisotropic behaviour of near ecliptic slow solar wind using the same methodology (described below) as that of Horbury et al. (2008) and (ii) the dependence of the anisotropic behaviour of SWT as a function of the heliospheric latitude.Method:We apply the wavelet method to calculate the turbulent power spectra of the magnetic field fluctuations parallel and perpendicular to the local mean magnetic field (LMF). According to Horbury et al., LMF for a given scale (or size) is obtained using an envelope of the envelope of that size. Results:(i) SSW intervals always show near -5/3 perpendicular spectra. Unlike the fast solar wind (FSW) intervals, for SSW, we often find intervals where power parallel to the mean field is not observed. For a few intervals with sufficient power in parallel direction, slow wind turbulence also exhibit -2 parallel spectra similar to FSW.(ii) The behaviours of parallel and perpendicular power spectra are found to be independent of the heliospheric latitude. Conclusion:In the current study we do not find significant influence of the heliospheric latitude on the spectral slopes of parallel and perpendicular

  16. Insights into the Performance of SD Bioline Malaria Ag P.f/Pan Rapid Diagnostic Test andPlasmodium falciparumHistidine-Rich Protein 2 Gene Variation in Madagascar.

    Science.gov (United States)

    Willie, Nigani; Mehlotra, Rajeev K; Howes, Rosalind E; Rakotomanga, Tovonahary A; Ramboarina, Stephanie; Ratsimbasoa, Arsène C; Zimmerman, Peter A

    2018-03-19

    Plasmodium falciparum histidine-rich protein 2 (PfHRP2) forms the basis of many current malaria rapid diagnostic tests (RDTs). However, the parasites lacking part or all of the pfhrp2 gene do not express the PfHRP2 protein and are, therefore, not identifiable by PfHRP2-detecting RDTs. We evaluated the performance of the SD Bioline Malaria Ag P.f/Pan RDT together with pfhrp2 variation in Madagascar. Genomic DNA isolated from 260 patient blood samples were polymerase chain reaction (PCR)-amplified for the parasite 18S rRNA and pfhrp2 genes. Post-PCR ligation detection reaction-fluorescent microsphere assay (LDR-FMA) was performed for the identification of parasite species. Plasmodium falciparum histidine-rich protein 2 amplicons were sequenced. Polymerase chain reaction diagnosis of patient samples showed that 29% (75/260) were infected and P. falciparum was present in 95% (71/75) of these PCR-positive samples. Comparing RDT and P. falciparum detection by LDR-FMA, eight samples were RDT negative but P. falciparum positive (false negatives), all of which were pfhrp2 positive. The sensitivity and specificity of the RDT were 87% and 90%, respectively. Seventy-three samples were amplified for pfhrp2 , from which nine randomly selected amplicons were sequenced, yielding 13 sequences. Amplification of pfhrp2 , combined with RDT analysis and P. falciparum detection by LDR-FMA, showed that there was no indication of pfhrp2 deletion. Sequence analysis of pfhrp2 showed that the correlation between pfhrp2 sequence structure and RDT detection rates was unclear. Although the observed absence of pfhrp2 deletion from the samples screened here is encouraging, continued monitoring of the efficacy of the SD Bioline Malaria Ag P.f/Pan RDT for malaria diagnosis in Madagascar is warranted.

  17. Incommensurate correlations in the anisotropic triangular Heisenberg lattice

    Science.gov (United States)

    Weichselbaum, Andreas; White, Steven R.

    2011-12-01

    We study the anisotropic spin-1/2 antiferromagnetic triangular Heisenberg lattice in two dimensions, seen as a set of chains with couplings J (J') along (in-between) chains, respectively. Our focus is on the incommensurate correlation that emerges in this system in a wide parameter range due to the intrinsic frustration of the spins. We study this system with traditional density matrix renormalization group using cylindrical boundary conditions to least constrain possible incommensurate order. Despite that the limit of essentially decoupled chains J'/J≲0.5 is not very accessible numerically, it appears that the spin-spin correlations remain incommensurate for any finite 0JC', where JC'/J>1. The incommensurate wave vector qJ, however, approaches the commensurate value corresponding to the antiferromagnetic correlation of a single chain very rapidly with decreasing J'/J, roughly as qJ˜π-c1(J'/J)ne-c2J/J'.

  18. Anisotropic hydrodynamics, holography and the chiral magnetic effect

    Energy Technology Data Exchange (ETDEWEB)

    Gahramanov, Ilmar; Kalaydzhyan, Tigran; Kirsch, Ingo [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Hamburg Univ. (Germany). Zentrum fuer Mathematische Physik

    2012-03-15

    We discuss a possible dependence of the chiral magnetic effect (CME) on the elliptic flow coefficient {upsilon}{sub 2}. We first study this in a hydrodynamic model for a static anisotropic plasma with multiple anomalous U(1) currents. In the case of two charges, one axial and one vector, the CME formally appears as a first-order transport coefficient in the vector current. We compute this transport coefficient and show its dependence on {upsilon}{sub 2}. We also determine the CME-coefficient from first-order corrections to the dual AdS background using the fluid-gravity duality. For small anisotropies, we find numerical agreement with the hydrodynamic result. (orig.)

  19. Saint-Venant torsion of non-homogeneous anisotropic bars

    Directory of Open Access Journals (Sweden)

    John T. Katsikadelis

    2016-01-01

    Full Text Available The BEM is applied to the solution of the torsion problem of non-homogeneous anisotropic non-circular prismatic bars. The problem is formulated in terms of the warping function. This formulation leads to a second order partial differential equation with variable coefficients, subjected to a generalized Neumann type boundary condition. The problem is solved using the Analog Equation Method (AEM. According to this method, the governing equation is replaced by a Poisson’s equation subjected to a fictitious source under the same boundary condition. The fictitious load is established using the Boundary Element Method (BEM after expanding it into a finite series of radial basis functions. The method has all the advantages of the pure BEM, since the discretization and integration are limited only on to the boundary. Numerical examples are presented which illustrate the efficiency and accuracy of the method.

  20. Lattice models of directed and semiflexible polymers in anisotropic environment

    International Nuclear Information System (INIS)

    Haydukivska, K; Blavatska, V

    2015-01-01

    We study the conformational properties of polymers in presence of extended columnar defects of parallel orientation. Two classes of macromolecules are considered: the so-called partially directed polymers with preferred orientation along direction of the external stretching field and semiflexible polymers. We are working within the frames of lattice models: partially directed self-avoiding walks (PDSAWs) and biased self-avoiding walks (BSAWs). Our numerical analysis of PDSAWs reveals, that competition between the stretching field and anisotropy caused by presence of extended defects leads to existing of three characteristic length scales in the system. At each fixed concentration of disorder we found a transition point, where the influence of extended defects is exactly counterbalanced by the stretching field. Numerical simulations of BSAWs in anisotropic environment reveal an increase of polymer stiffness. In particular, the persistence length of semiflexible polymers increases in presence of disorder. (paper)

  1. The Adhesive System and Anisotropic Shear Force of Guizhou Gastromyzontidae

    Science.gov (United States)

    Zou, Jun; Wang, Jinrong; Ji, Chen

    2016-11-01

    The Guizhou gastromyzontidae (Beaufortia kweichowensis) can adhere to slippery and fouled surfaces in torrential streams. A unique adhesive system utilized by the fish was observed by microscope and CLSM as an attachment disc sealed by a round belt of micro bubbles. The system is effective in wet or underwater environments and can resist a normal pulling force up to 1000 times the fish’s weight. Moreover, a mechanism for passive anisotropic shear force was observed. The shear forces of the fish under different conditions were measured, showing that passive shear force plays an important role in wet environments. The adhesive system of the fish was compared with other biological adhesion principles, from which we obtained potential values for the system that refer to the unique micro sealing and enhanced adhesion in a wet environment.

  2. Shear-free gravitational waves in an anisotropic universe

    International Nuclear Information System (INIS)

    Hogan, P.A.; O'Shea, E.M.

    2002-01-01

    We study gravitational waves propagating through an anisotropic Bianchi type I dust-filled universe (containing the Einstein-de Sitter universe as a special case). The waves are modeled as small perturbations of this background cosmological model and we choose a family of null hypersurfaces in this space-time to act as the histories of the wave fronts of the radiation. We find that the perturbations we generate can describe pure gravitational radiation if and only if the null hypersurfaces are shear-free. We calculate the gauge-invariant small perturbations explicitly in this case. How these differ from the corresponding perturbations when the background space-time is isotropic is clearly exhibited

  3. Wavefront sensing for anisotropic turbulence using digital holography

    Science.gov (United States)

    Thurman, Samuel T.; Gatt, Philip; Alley, Thomas

    2016-09-01

    We report on digital holographic imaging through atmospheric turbulence. Data recorded with aberrations is corrected during post processing using an iterative sharpness-metric maximization algorithm. Assuming the correction cancels the actual wavefront error, this process is equivalent to wavefront sensing. Much of our past work focused on imaging through isotropic turbulence with phase corrections using a Zernike-polynomial expansion. Here, we describe algorithm modifications for imaging through anisotropic turbulence, similar to what is seen when looking through the aero-optic boundary layer surrounding a moving aircraft. Specifically, we explore tradeoffs associated with switching from a Zernike representation to Karhunen-Loève basis functions. In some cases, the dimensionality of the phase correction estimation algorithm can be reduced significantly by this change. This reduces the computational burden

  4. A fast algorithm for 3D azimuthally anisotropic velocity scan

    KAUST Repository

    Hu, Jingwei

    2014-11-11

    © 2014 European Association of Geoscientists & Engineers. The conventional velocity scan can be computationally expensive for large-scale seismic data sets, particularly when the presence of anisotropy requires multiparameter scanning. We introduce a fast algorithm for 3D azimuthally anisotropic velocity scan by generalizing the previously proposed 2D butterfly algorithm for hyperbolic Radon transforms. To compute semblance in a two-parameter residual moveout domain, the numerical complexity of our algorithm is roughly O(N3logN) as opposed to O(N5) of the straightforward velocity scan, with N being the representative of the number of points in a particular dimension of either data space or parameter space. Synthetic and field data examples demonstrate the superior efficiency of the proposed algorithm.

  5. Optimal propulsion of an undulating slender body with anisotropic friction.

    Science.gov (United States)

    Darbois Texier, Baptiste; Ibarra, Alejandro; Melo, Francisco

    2018-01-24

    This study investigates theoretically and numerically the propulsive sliding of a slender body. The body sustains a transverse and propagative wave along its main axis, and undergoes anisotropic friction caused by its surface texture sliding on the floor. A model accounting for the anisotropy of frictional forces acting on the body is implemented. This describes the propulsive force and gives the optimal undulating parameters for efficient forward propulsion. The optimal wave characteristics are effectively compared to the undulating motion of a slithering snakes, as well as with the motion of sandfish lizards swimming through the sand. Furthermore, numerical simulations have indicated the existence of certain specialized segments along the body that are highly efficient for propulsion, explaining why snakes lift parts of their body while slithering. Finally, the inefficiency of slithering as a form of locomotion to ascend a slope is discussed.

  6. Vlasov tokamak equilibria with sheared toroidal flow and anisotropic pressure

    Energy Technology Data Exchange (ETDEWEB)

    Kuiroukidis, Ap, E-mail: kouirouki@astro.auth.gr [Technological Education Institute of Serres, 62124 Serres (Greece); Throumoulopoulos, G. N., E-mail: gthroum@uoi.gr [Department of Physics, University of Ioannina, GR 451 10 Ioannina (Greece); Tasso, H., E-mail: het@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, D-85748 Garching (Germany)

    2015-08-15

    By choosing appropriate deformed Maxwellian ion and electron distribution functions depending on the two particle constants of motion, i.e., the energy and toroidal angular momentum, we reduce the Vlasov axisymmetric equilibrium problem for quasineutral plasmas to a transcendental Grad-Shafranov-like equation. This equation is then solved numerically under the Dirichlet boundary condition for an analytically prescribed boundary possessing a lower X-point to construct tokamak equilibria with toroidal sheared ion flow and anisotropic pressure. Depending on the deformation of the distribution functions, these steady states can have toroidal current densities either peaked on the magnetic axis or hollow. These two kinds of equilibria may be regarded as a bifurcation in connection with symmetry properties of the distribution functions on the magnetic axis.

  7. Numerical analysis of anisotropic diffusion effect on ICF hydrodynamic instabilities

    Directory of Open Access Journals (Sweden)

    Olazabal-Loumé M.

    2013-11-01

    Full Text Available The effect of anisotropic diffusion on hydrodynamic instabilities in the context of Inertial Confinement Fusion (ICF flows is numerically assessed. This anisotropy occurs in indirect-drive when laminated ablators are used to modify the lateral transport [1,2]. In direct-drive, non-local transport mechanisms and magnetic fields may modify the lateral conduction [3]. In this work, numerical simulations obtained with the code PERLE [4], dedicated to linear stability analysis, are compared with previous theoretical results [5]. In these approaches, the diffusion anisotropy can be controlled by a characteristic coefficient which enables a comprehensive study. This work provides new results on the ablative Rayleigh-Taylor (RT, ablative Richtmyer-Meshkov (RM and Darrieus-Landau (DL instabilities.

  8. Anisotropic ordering in a two-temperature lattice gas

    DEFF Research Database (Denmark)

    Szolnoki, Attila; Szabó, György; Mouritsen, Ole G.

    1997-01-01

    We consider a two-dimensional lattice gas model with repulsive nearest- and next-nearest-neighbor interactions that evolves in time according to anisotropic Kawasaki dynamics. The hopping of particles along the principal directions is governed by two heat baths at different temperatures T-x and T-y...... of the higher temperature. In the resulting phase diagram in the T-x-T-y plane the critical temperature curve shows a weak maximum as a function of the parallel temperature which is confirmed by Monte Carlo simulations. Finite-size scaling analysis suggests that the model leaves the equilibrium universality...... class of the x-y model with cubic anisotropy and is described by the Ising exponents....

  9. Glueball Spectrum and Matrix Elements on Anisotropic Lattices

    Energy Technology Data Exchange (ETDEWEB)

    Y. Chen; A. Alexandru; S.J. Dong; T. Draper; I. Horvath; F.X. Lee; K.F. Liu; N. Mathur; C. Morningstar; M. Peardon; S. Tamhankar; B.L. Young; J.B. Zhang

    2006-01-01

    The glueball-to-vacuum matrix elements of local gluonic operators in scalar, tensor, and pseudoscalar channels are investigated numerically on several anisotropic lattices with the spatial lattice spacing ranging from 0.1fm - 0.2fm. These matrix elements are needed to predict the glueball branching ratios in J/{psi} radiative decays which will help identify the glueball states in experiments. Two types of improved local gluonic operators are constructed for a self-consistent check and the finite volume effects are studied. We find that lattice spacing dependence of our results is very weak and the continuum limits are reliably extrapolated, as a result of improvement of the lattice gauge action and local operators. We also give updated glueball masses with various quantum numbers.

  10. Spectrum of perturbations in anisotropic inflationary universe with vector hair

    Energy Technology Data Exchange (ETDEWEB)

    Himmetoglu, Burak, E-mail: burak@physics.umn.edu [School of Physics and Astronomy, University of Minnesota, 116 Church Street S.E., Minneapolis, MN 55455 (United States)

    2010-03-01

    We study both the background evolution and cosmological perturbations of anisotropic inflationary models supported by coupled scalar and vector fields. The models we study preserve the U(1) gauge symmetry associated with the vector field, and therefore do not possess instabilities associated with longitudinal modes (which instead plague some recently proposed models of vector inflation and curvaton). We first intoduce a model in which the background anisotropy slowly decreases during inflation; we then confirm the stability of the background solution by studying the quadratic action for all the perturbations of the model. We then compute the spectrum of the h{sub ×} gravitational wave polarization. The spectrum we find breaks statistical isotropy at the largest scales and reduces to the standard nearly scale invariant form at small scales. We finally discuss the possible relevance of our results to the large scale CMB anomalies.

  11. Anisotropic Exchange Interaction in the Conical Magnetic Phase of Erbium

    DEFF Research Database (Denmark)

    Jensen, J.

    1974-01-01

    From a general two ion spin Hamiltonian, an expression is deduced for the energies of spin waves propagating in a hexagonal solid in which the magnetic moments are ordered in a conical or helical structure. The spin wave dispersion relation in the c direction of Er in its conical magnetic phase...... at 4.5K, which has been studied by Nicklow et al (1971) is reanalysed. In this analysis an alternative kind of anisotropic coupling between the total angular moments (Ji and Jj) on the sites i and j is introduced which is proportional to the following combination of Racah operators: O2, -2(Ji), O2, -2......(Jj), expressed with respect to a coordinate system with the z axis along the c direction. The resulting anisotropy (both the constant and the q dependent part) is reduced by an order of magnitude in comparison with that deduced by Nicklow et al (1971). The constant anisotropy is found to be equal...

  12. A hydrostatic stress-dependent anisotropic model of viscoplasticity

    Science.gov (United States)

    Robinson, D. N.; Tao, Q.; Verrilli, M. J.

    1994-01-01

    A hydrostatic stress-dependent, anisotropic model of viscoplasticity is formulated as an extension of Bodner's model. This represents a further extension of the isotropic Bodner model over that made to anisotropy by Robinson and MitiKavuma. Account is made of the inelastic deformation that can occur in metallic composites under hydrostatic stress. A procedure for determining the material parameters is identified that is virtually identical to the established characterization procedure for the original Bodner model. Characterization can be achieved using longitudinal/transverse tensile and shear tests and hydrostatic stress tests; alternatively, four off-axis tensile tests can be used. Conditions for a yield stress minimum under off-axis tension are discussed. The model is applied to a W/Cu composite; characterization is made using off-axis tensile data generated at NASA Lewis Research Center (LeRC).

  13. Effect of orbital symmetry on the anisotropic superexchange interaction

    International Nuclear Information System (INIS)

    Kim, Beom Hyun; Min, B I

    2011-01-01

    Employing the microscopic superexchange model incorporating the effect of spin-orbit interaction, we have investigated the Dzyaloshinsky-Moriya (DM) interaction in perovskite transition-metal (TM) oxides and explored the interplay between the DM interaction and the TM-3d orbital symmetry. For d 3 and d 5 systems with isotropic orbital symmetry, the DM vectors are well described by a simple symmetry analysis considering only the bond geometry. In contrast, the DM interaction for d 4 systems with anisotropic orbital symmetry shows slightly different behavior, which does not obey simple symmetry analysis. The direction as well as the strength of the DM vector varies depending on the occupied orbital shape. We have understood this behavior based on the orbital symmetry induced by local crystal field variation.

  14. Jet quenching effects on the anisotropic flow at RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, R.P.G. [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, SP, 09210-170 (Brazil); Noronha, J. [Instituto de Física, Universidade de São Paulo, C.P. 66318, 05315-970 São Paulo, SP (Brazil); Denicol, Gabriel S. [Department of Physics, McGill University, 3600 University Street, Montreal, Quebec, H3A 2T8 (Canada)

    2014-12-15

    In this article we investigate how the energy and momentum deposited by partonic dijets in the quark–gluon plasma may perturb the geometry-induced hydrodynamic expansion of the bulk nuclear matter created in heavy ion collisions at the RHIC. The coupling between the jets and the medium is done through a source term in the energy–momentum conservation equations for ideal hydrodynamics. We concentrate our attention at mid-rapidity and solve the equations event-by-event imposing boost-invariance. For p{sub T}≳1 GeV the anisotropic flow is found to be considerably enhanced, if the dijets deposit on average more than 12 GeV in the medium (or equivalently 6 GeV for each jet of the pair), which corresponds, in our model, to an average suppression greater than 65% of the initial jet transverse energy.

  15. Polymer Nanocomposites Containing Anisotropic Metal Nanostructures as Internal Strain Indicators

    Directory of Open Access Journals (Sweden)

    Giacomo Ruggeri

    2010-02-01

    Full Text Available Polymer/metal nanocomposite containing intrinsically anisotropic metal nanostructures such as metal nanorods and nanowires appeared extremely more sensitive and responsive to mechanical stimuli than nanocomposites containing spherical nanoparticles. After uniaxial stretching of the supporting polymer matrix (poly(vinyl alcohol, the elongated silver nanostructures embedded at low concentration into the polymer matrix (<1 wt % of Ag assume the direction of the drawing, yielding materials with a strong dichroic response of the absorption behavior. Accordingly, the film changed its color when observed under linearly polarized light already at moderate drawings. The results obtained suggest that nanocomposite films have potential in applications such as color polarizing filters, radiation responsive polymeric objects and smart flexible films in packaging applications.

  16. Indicator for hydration balance during haemodialysis based on anisotropic FEM

    International Nuclear Information System (INIS)

    Freiberger, M; Brunner, P; Mayer, M; Scharfetter, H; Surkhi, O I; Riu, P J

    2008-01-01

    The current paper proposes a new indicator for well-balanced dehydration of patients undergoing a haemodialysis. It is based on an estimator for the extra-cellular volume and the ultrafiltration rate. The extra-cellular fluid was computed from continuous tetrapolar bio-impedance measurements taken on the lower leg in a frequency range of several kilohertz up to 500 kHz. Finite element simulations on different leg models with anisotropic conductivities calculated with Cole models were carried out in order to incorporate the significant anisotropy of human tissue into the estimation process. The indicator was tested on measurement data gathered from 25 persons during 150 haemodialysis sessions. Its performance was determined by computing ROC curves. Results of the data analysis are reported

  17. Tubular phase of self-avoiding anisotropic crystalline membranes

    International Nuclear Information System (INIS)

    Bowick, M.; Travesset, A.

    1999-01-01

    We analyze the tubular phase of self-avoiding anisotropic crystalline membranes. A careful analysis using renormalization group arguments together with symmetry requirements motivates the simplest form of the large-distance free energy describing fluctuations of tubular configurations. The non-self-avoiding limit of the model is shown to be exactly solvable. For the full self-avoiding model we compute the critical exponents using an var-epsilon expansion about the upper critical embedding dimension for general internal dimension D and embedding dimension d. We then exhibit various methods for reliably extrapolating to the physical point (D=2,d=3). Our most accurate estimates are ν=0.62 for the Flory exponent and ζ=0.80 for the roughness exponent. copyright 1999 The American Physical Society

  18. A 2-D model for friction of complex anisotropic surfaces

    Science.gov (United States)

    Costagliola, Gianluca; Bosia, Federico; Pugno, Nicola M.

    2018-03-01

    The friction force observed at macroscale is the result of interactions at various lower length scales that are difficult to model in a combined manner. For this reason, simplified approaches are required, depending on the specific aspect to be investigated. In particular, the dimensionality of the system is often reduced, especially in models designed to provide a qualitative description of frictional properties of elastic materials, e.g. the spring-block model. In this paper, we implement for the first time a two dimensional extension of the spring-block model, applying it to structured surfaces and investigating by means of numerical simulations the frictional behaviour of a surface in the presence of features like cavities, pillars or complex anisotropic structures. We show how friction can be effectively tuned by appropriate design of such surface features.

  19. Anisotropic charged impurity-limited carrier mobility in monolayer phosphorene

    Energy Technology Data Exchange (ETDEWEB)

    Ong, Zhun-Yong; Zhang, Gang; Zhang, Yong Wei [Institute of High Performance Computing, A*STAR, Singapore 138632 (Singapore)

    2014-12-07

    The room temperature carrier mobility in atomically thin 2D materials is usually far below the intrinsic limit imposed by phonon scattering as a result of scattering by remote charged impurities in its environment. We simulate the charged impurity-limited carrier mobility μ in bare and encapsulated monolayer phosphorene. We find a significant temperature dependence in the carrier mobilities (μ ∝ T{sup −γ}) that results from the temperature variability of the charge screening and varies with the crystal orientation. The anisotropy in the effective mass leads to an anisotropic carrier mobility, with the mobility in the armchair direction about one order of magnitude larger than in the zigzag direction. In particular, this mobility anisotropy is enhanced at low temperatures and high carrier densities. Under encapsulation with a high-κ overlayer, the mobility increases by up to an order of magnitude although its temperature dependence and its anisotropy are reduced.

  20. Speckle suppressing anisotropic diffusion filter for medical ultrasound images.

    Science.gov (United States)

    Ovireddy, Saraniya; Muthusamy, Ezhilarasi

    2014-04-01

    Ultrasonography is often preferred over the other medical imaging modalities due to its noninvasive nature, cost-effectiveness, and portability. However, the resolution of the ultrasound image greatly depends upon the presence of speckle noise. Speckle noise generally tends to reduce the image resolution and contrast, thereby reducing the diagnostic resolution of this imaging modality. In this paper, we propose a speckle suppressing anisotropic diffusion (SSAD) filter, to remove the speckle noise from B-Mode Ultrasound images. The performance of the SSAD filter is compared with the existing diffusion filters. The evaluation is based on their application to images simulated by Field II (developed by Jensen et al.). The algorithms were also tested for clinical ultrasound images of polycystic ovaries obtained from HDI 5000 Ultrasound Scanner. Performance evaluation was done by both numerical and functional parameters. The proposed filter yields better results in terms of greatest structural similarity index map (SSIM) of 0.95 and accuracy of 99.5.

  1. Electrostatic images for underwater anisotropic conductive half spaces

    International Nuclear Information System (INIS)

    Flykt, M.; Lindell, I.; Eloranta, E.

    1998-01-01

    A static image principle makes it possible to derive analytical solutions to some basic geometries for DC fields. The underwater environment is especially difficult both from the theoretical and practical point of view. However, there are increasing demands that also the underwater geological formations should be studied in detail. The traditional image of a point source lies at the mirror point of the original. When anisotropic media is involved, however, the image location can change and the image source may be a continues, sector-like distribution. In this paper some theoretical considerations are carried out in the case where the lower half space can have a very general anisotropy in terms of electrical conductivity, while the upper half space is assumed isotropic. The reflection potential field is calculated for different values of electrical conductivity. (orig.)

  2. Complex emergent dynamics of anisotropic swarms: Convergence vs oscillation

    International Nuclear Information System (INIS)

    Chu Tianguang; Wang Long; Chen Tongwen; Mu Shumei

    2006-01-01

    This paper considers an anisotropic swarm model with a simple attraction and repulsion function. It is shown that the members of a reciprocal swarm will aggregate and eventually form a cohesive cluster of finite size around the swarm center. Moreover, the swarm system is also completely stable, i.e., every solution converges to the set of equilibrium points of the system. These results are also valid for a class of non-reciprocal swarms under the detailed balance condition on coupling weights. For general non-reciprocal swarms, numerical simulations are worked out to demonstrate more complex oscillatory motions in the systems. The study provides further insight into the effect of the interaction pattern on the collective behavior of a swarm system

  3. Anisotropic magnetoresistance components in (Ga,Mn)As.

    Science.gov (United States)

    Rushforth, A W; Výborný, K; King, C S; Edmonds, K W; Campion, R P; Foxon, C T; Wunderlich, J; Irvine, A C; Vasek, P; Novák, V; Olejník, K; Sinova, Jairo; Jungwirth, T; Gallagher, B L

    2007-10-05

    We explore the basic physical origins of the noncrystalline and crystalline components of the anisotropic magnetoresistance (AMR) in (Ga,Mn)As. The sign of the noncrystalline AMR is found to be determined by the form of spin-orbit coupling in the host band and by the relative strengths of the nonmagnetic and magnetic contributions to the Mn impurity potential. We develop experimental methods yielding directly the noncrystalline and crystalline AMR components which are then analyzed independently. We report the observation of an AMR dominated by a large uniaxial crystalline component and show that AMR can be modified by local strain relaxation. Generic implications of our findings for other dilute moment systems are discussed.

  4. Single atom anisotropic magnetoresistance on a topological insulator surface

    KAUST Repository

    Narayan, Awadhesh

    2015-03-12

    © 2015 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. We demonstrate single atom anisotropic magnetoresistance on the surface of a topological insulator, arising from the interplay between the helical spin-momentum-locked surface electronic structure and the hybridization of the magnetic adatom states. Our first-principles quantum transport calculations based on density functional theory for Mn on Bi2Se3 elucidate the underlying mechanism. We complement our findings with a two dimensional model valid for both single adatoms and magnetic clusters, which leads to a proposed device setup for experimental realization. Our results provide an explanation for the conflicting scattering experiments on magnetic adatoms on topological insulator surfaces, and reveal the real space spin texture around the magnetic impurity.

  5. Anisotropic charged impurity-limited carrier mobility in monolayer phosphorene

    International Nuclear Information System (INIS)

    Ong, Zhun-Yong; Zhang, Gang; Zhang, Yong Wei

    2014-01-01

    The room temperature carrier mobility in atomically thin 2D materials is usually far below the intrinsic limit imposed by phonon scattering as a result of scattering by remote charged impurities in its environment. We simulate the charged impurity-limited carrier mobility μ in bare and encapsulated monolayer phosphorene. We find a significant temperature dependence in the carrier mobilities (μ ∝ T −γ ) that results from the temperature variability of the charge screening and varies with the crystal orientation. The anisotropy in the effective mass leads to an anisotropic carrier mobility, with the mobility in the armchair direction about one order of magnitude larger than in the zigzag direction. In particular, this mobility anisotropy is enhanced at low temperatures and high carrier densities. Under encapsulation with a high-κ overlayer, the mobility increases by up to an order of magnitude although its temperature dependence and its anisotropy are reduced

  6. Relativistic modeling of compact stars for anisotropic matter distribution

    Energy Technology Data Exchange (ETDEWEB)

    Maurya, S.K. [University of Nizwa, Department of Mathematical and Physical Sciences, College of Arts and Science, Nizwa (Oman)

    2017-05-15

    In this paper we have solved Einstein's field equations of spherically symmetric spacetime for anisotropic matter distribution by assuming physically valid expressions of the metric function e{sup λ} and radial pressure (p{sub r}). Next we have discussed the physical properties of the model in details by taking the radial pressure p{sub r} equal to zero at the boundary of the star. The physical analysis of the star indicates that its model parameters such as density, redshift, radial pressure, transverse pressure and anisotropy are well behaved. Also we have obtained the mass and radius of our compact star which are 2.29M {sub CircleDot} and 11.02 km, respectively. It is observed that the model obtained here for compact stars is compatible with the mass and radius of the strange star PSR 1937 +21. (orig.)

  7. Emerging anisotropic compact stars in f(G,T) gravity

    Energy Technology Data Exchange (ETDEWEB)

    Shamir, M.F.; Ahmad, Mushtaq [National University of Computer and Emerging Sciences, Lahore (Pakistan)

    2017-10-15

    The possible emergence of compact stars has been investigated in the recently introduced modified Gauss-Bonnet f(G,T) gravity, where G is the Gauss-Bonnet term and T is the trace of the energy-momentum tensor (Sharif and Ikram, Eur Phys J C 76:640, 2016). Specifically, for this modified f(G,T) theory, the analytic solutions of Krori and Barua have been applied to an anisotropic matter distribution. To determine the unknown constants appearing in the Krori and Barua metric, the well-known three models of the compact stars, namely 4U1820-30, Her X-I, and SAX J 1808.4-3658 have been used. The analysis of the physical behaviour of the compact stars has been presented and the physical features like energy density and pressure, energy conditions, static equilibrium, stability, measure of anisotropy, and regularity of the compact stars, have been discussed. (orig.)

  8. Convex variational problems linear, nearly linear and anisotropic growth conditions

    CERN Document Server

    Bildhauer, Michael

    2003-01-01

    The author emphasizes a non-uniform ellipticity condition as the main approach to regularity theory for solutions of convex variational problems with different types of non-standard growth conditions. This volume first focuses on elliptic variational problems with linear growth conditions. Here the notion of a "solution" is not obvious and the point of view has to be changed several times in order to get some deeper insight. Then the smoothness properties of solutions to convex anisotropic variational problems with superlinear growth are studied. In spite of the fundamental differences, a non-uniform ellipticity condition serves as the main tool towards a unified view of the regularity theory for both kinds of problems.

  9. Multi-critical points in weakly anisotropic magnetic systems

    International Nuclear Information System (INIS)

    Basten, J.A.J.

    1979-02-01

    This report starts with a rather extensive presentation of the concepts and ideas which constitute the basis of the modern theory of static critical phenomena. It is shown how at a critical point the semi-phenomenological concepts of universality and scaling are directly related to the divergence of the correlation length and how they are extended to a calculational method for critical behaviour in Wilson's Renormalization-Group (RG) approach. Subsequently the predictions of the molecular-field and RG-theories on the phase transitions and critical behaviour in weakly anisotropic antiferromagnets are treated. In a magnetic field applied along the easy axis, these materials can display an (H,T) phase diagram which contains either a bicritical point or a tetracritical point. Especially the behaviour close to these multi-critical points, as predicted by the extended-scaling theory, is discussed. (Auth.)

  10. Mixing of solids in different mixing devices

    Indian Academy of Sciences (India)

    The results obtained by those three devices, the particle size effect and cohesion indexes, bring us to the conclusion that static mixers could be used for mixing of powders, but their shape, number of mixing elements and the mixer length should be adapted for each mixture separately, experimentally and mathematically, ...

  11. Intermittent Anisotropic Turbulence Detected by THEMIS in the Magnetosheath

    Science.gov (United States)

    Macek, W. M.; Wawrzaszek, A.; Kucharuk, B.; Sibeck, D. G.

    2017-12-01

    Following our previous study of Time History of Events and Macroscale Interactions during Substorms (THEMIS) data, we consider intermittent turbulence in the magnetosheath depending on various conditions of the magnetized plasma behind the Earth’s bow shock and now also near the magnetopause. Namely, we look at the fluctuations of the components of the Elsässer variables in the plane perpendicular to the scale-dependent background magnetic fields and along the local average ambient magnetic fields. We have shown that Alfvén fluctuations often exhibit strong anisotropic non-gyrotropic turbulent intermittent behavior resulting in substantial deviations of the probability density functions from a normal Gaussian distribution with a large kurtosis. In particular, for very high Alfvénic Mach numbers and high plasma beta, we have clear anisotropy with non-Gaussian statistics in the transverse directions. However, along the magnetic field, the kurtosis is small and the plasma is close to equilibrium. On the other hand, intermittency becomes weaker for moderate Alfvén Mach numbers and lower values of the plasma parameter beta. It also seems that the degree of intermittency of turbulence for the outgoing fluctuations propagating relative to the ambient magnetic field is usually similar as for the ingoing fluctuations, which is in agreement with approximate equipartition of energy between these oppositely propagating Alfvén waves. We believe that the different characteristics of this intermittent anisotropic turbulent behavior in various regions of space and astrophysical plasmas can help identify nonlinear structures responsible for deviations of the plasma from equilibrium.

  12. Elastic orthorhombic anisotropic parameter inversion: An analysis of parameterization

    KAUST Repository

    Oh, Juwon

    2016-09-15

    The resolution of a multiparameter full-waveform inversion (FWI) is highly influenced by the parameterization used in the inversion algorithm, as well as the data quality and the sensitivity of the data to the elastic parameters because the scattering patterns of the partial derivative wavefields (PDWs) vary with parameterization. For this reason, it is important to identify an optimal parameterization for elastic orthorhombic FWI by analyzing the radiation patterns of the PDWs for many reasonable model parameterizations. We have promoted a parameterization that allows for the separation of the anisotropic properties in the radiation patterns. The central parameter of this parameterization is the horizontal P-wave velocity, with an isotropic scattering potential, influencing the data at all scales and directions. This parameterization decouples the influence of the scattering potential given by the P-wave velocity perturbation fromthe polar changes described by two dimensionless parameter perturbations and from the azimuthal variation given by three additional dimensionless parameters perturbations. In addition, the scattering potentials of the P-wave velocity perturbation are also decoupled from the elastic influences given by one S-wave velocity and two additional dimensionless parameter perturbations. The vertical S-wave velocity is chosen with the best resolution obtained from S-wave reflections and converted waves, little influence on P-waves in conventional surface seismic acquisition. The influence of the density on observed data can be absorbed by one anisotropic parameter that has a similar radiation pattern. The additional seven dimensionless parameters describe the polar and azimuth variations in the P- and S-waves that we may acquire, with some of the parameters having distinct influences on the recorded data on the earth\\'s surface. These characteristics of the new parameterization offer the potential for a multistage inversion from high symmetry

  13. Imaging anisotropic layering with Bayesian inversion of multiple data types

    Science.gov (United States)

    Bodin, T.; Leiva, J.; Romanowicz, B.; Maupin, V.; Yuan, H.

    2016-07-01

    Azimuthal anisotropy is a powerful tool to reveal information about both the present structure and past evolution of the mantle. Anisotropic images of the upper mantle are usually obtained by analysing various types of seismic observables, such as surface wave dispersion curves or waveforms, SKS splitting data, or receiver functions. These different data types sample different volumes of the earth, they are sensitive to different length scales, and hence are associated with different levels of uncertainties. They are traditionally interpreted separately, and often result in incompatible models. We present a Bayesian inversion approach to jointly invert these different data types. Seismograms for SKS and P phases are directly inverted using a cross-convolution approach, thus avoiding intermediate processing steps, such as numerical deconvolution or computation of splitting parameters. Probabilistic 1-D profiles are obtained with a transdimensional Markov chain Monte Carlo scheme, in which the number of layers, as well as the presence or absence of anisotropy in each layer, are treated as unknown parameters. In this way, seismic anisotropy is only introduced if required by the data. The algorithm is used to resolve both isotropic and anisotropic layering down to a depth of 350 km beneath two seismic stations in North America in two different tectonic settings: the stable Canadian shield (station FFC) and the tectonically active southern Basin and Range Province (station TA-214A). In both cases, the lithosphere-asthenosphere boundary is clearly visible, and marked by a change in direction of the fast axis of anisotropy. Our study confirms that azimuthal anisotropy is a powerful tool for detecting layering in the upper mantle.

  14. An anisotropic elastoplastic constitutive formulation generalised for orthotropic materials

    Science.gov (United States)

    Mohd Nor, M. K.; Ma'at, N.; Ho, C. S.

    2018-03-01

    This paper presents a finite strain constitutive model to predict a complex elastoplastic deformation behaviour that involves very high pressures and shockwaves in orthotropic materials using an anisotropic Hill's yield criterion by means of the evolving structural tensors. The yield surface of this hyperelastic-plastic constitutive model is aligned uniquely within the principal stress space due to the combination of Mandel stress tensor and a new generalised orthotropic pressure. The formulation is developed in the isoclinic configuration and allows for a unique treatment for elastic and plastic orthotropy. An isotropic hardening is adopted to define the evolution of plastic orthotropy. The important feature of the proposed hyperelastic-plastic constitutive model is the introduction of anisotropic effect in the Mie-Gruneisen equation of state (EOS). The formulation is further combined with Grady spall failure model to predict spall failure in the materials. The proposed constitutive model is implemented as a new material model in the Lawrence Livermore National Laboratory (LLNL)-DYNA3D code of UTHM's version, named Material Type 92 (Mat92). The combination of the proposed stress tensor decomposition and the Mie-Gruneisen EOS requires some modifications in the code to reflect the formulation of the generalised orthotropic pressure. The validation approach is also presented in this paper for guidance purpose. The \\varvec{ψ} tensor used to define the alignment of the adopted yield surface is first validated. This is continued with an internal validation related to elastic isotropic, elastic orthotropic and elastic-plastic orthotropic of the proposed formulation before a comparison against range of plate impact test data at 234, 450 and {895 ms}^{-1} impact velocities is performed. A good agreement is obtained in each test.

  15. Effective Orthorhombic Anisotropic Models for Wave field Extrapolation

    KAUST Repository

    Ibanez Jacome, Wilson

    2013-05-01

    Wavefield extrapolation in orthorhombic anisotropic media incorporates complicated but realistic models, to reproduce wave propagation phenomena in the Earth\\'s subsurface. Compared with the representations used for simpler symmetries, such as transversely isotropic or isotropic, orthorhombic models require an extended and more elaborated formulation that also involves more expensive computational processes. The acoustic assumption yields more efficient description of the orthorhombic wave equation that also provides a simplified representation for the orthorhombic dispersion relation. However, such representation is hampered by the sixth-order nature of the acoustic wave equation, as it also encompasses the contribution of shear waves. To reduce the computational cost of wavefield extrapolation in such media, I generate effective isotropic inhomogeneous models that are capable of reproducing the first-arrival kinematic aspects of the orthorhombic wavefield. First, in order to compute traveltimes in vertical orthorhombic media, I develop a stable, efficient and accurate algorithm based on the fast marching method. The derived orthorhombic acoustic dispersion relation, unlike the isotropic or transversely isotropic one, is represented by a sixth order polynomial equation that includes the fastest solution corresponding to outgoing P-waves in acoustic media. The effective velocity models are then computed by evaluating the traveltime gradients of the orthorhombic traveltime solution, which is done by explicitly solving the isotropic eikonal equation for the corresponding inhomogeneous isotropic velocity field. The inverted effective velocity fields are source dependent and produce equivalent first-arrival kinematic descriptions of wave propagation in orthorhombic media. I extrapolate wavefields in these isotropic effective velocity models using the more efficient isotropic operator, and the results compare well, especially kinematically, with those obtained from the

  16. Mechanical properties, anisotropic swelling behaviours and structures of jellyfish mesogloea.

    Science.gov (United States)

    Zhu, Jintang; Wang, Xuezhen; He, Changcheng; Wang, Huiliang

    2012-02-01

    Learning from nature is a promising way for designing and fabricating new materials with special properties. As the first step, we need to understand the structures and properties of the natural materials. In this work, we paid attention to the mesogloea of an edible jellyfish (Rhopilema esculenta Kishinouye) and mainly focused on its structure, mechanical and swelling properties. Scanning electron microscope (SEM) investigations show that jellyfish mesogloea has a well-developed anisotropic microstructure, which consists of nano-sized membranes connected with many fibres. The tensile and compressive properties of swollen and dried jellyfish mesogloea samples are measured. The jellyfish mesogloea displays very high tensile strength (0.17 MPa) and compressive strength (1.43 MPa) even with 99 wt % water. The mechanical properties of jellyfish mesogloea exceed most synthetic hydrogels with similar or even lower water contents. Swelling in acidic and basic buffer solutions weakens the mechanical properties of jellyfish mesogloea. The dried jellyfish mesogloea has very high tensile strength and modulus, which are very similar to those of synthetic plastics. The swelling properties of jellyfish mesogloea in solutions with different pH values were studied. The jellyfish mesogloea exhibits pH-sensitive and anisotropic swelling properties. The jellyfish mesogloea swells (expands) in height but deswells (shrinks) in length and width, without significant change in the volume. This phenomenon has never been reported for synthetic hydrogels. This study may provide gel scientists new ideas in designing and fabricating hydrogels with well-defined microstructures and unique mechanical and swelling properties. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. Domainal cleavage as an Anisotropic Reaction-diffusion Process

    Science.gov (United States)

    Mulchrone, Kieran; Meere, Patrick

    2017-04-01

    Domainal cleavage comprises zones dominated by quartz and feldspar (QF-domains) and zones dominated by Mica (M-domains) which form at low metamorphic grades. The protolith is typically fairly homogeneous mudstone, siltstone, sandstone or limestone. Wet diffusion or pressure solution along grain boundaries is a key mechanism in the development of domanial cleavage. However, this does not explain why M-domains become sub-regularly spaced, visually evident in coarser-grained rocks, and take on an anastomising morphology. The ratio of M to QF-domains by volume can range from 1 to 0.1 and lower i.e. in extreme cases M-domains are intermittent but regularly spaced. It is suggested here that an anisotropic reaction-diffusion process model can explain these features. The imposed stress field instantaneously leads to anisotropy of diffusion by narrowing intergranular channels perpendicular to the principal stress. This leads to a preferred diffusion of chemicals parallel to the principal stress direction and lower diffusion rates in the normal direction. Combining this with the chemical reaction of pressure solution produces an anisotropic reaction-diffusion system. Both isotropic and anistropic reaction diffusion systems lead to pattern formation as discovered by Alan Turing on the 1950's as an explanation for patterns found in animal skins such as spots and stripes. Thus domanial cleavage is a striped pattern induced by diffusion anisotropy combined with a chemical reaction. Furthermore, rates of chemical reaction in intergranular fluids is likely to be many orders of magnitude greater that rates of deformation. Therefore we expect domanial cleavage to form relatively rapidly. As deformation progresses the M-domains behave less competently and may be the site of enhanced shearing. An example from Co. Cork, Ireland demonstrates shear folding in low-grade metasedimentary rocks with reverse shear along M-domains at a high angle to the maximum compressive stress.

  18. Effect of chromium and aluminum addition on anisotropic and microstructural characteristics of ball milled nanocrystalline iron

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rajiv, E-mail: rajiv06484met@gmail.com [IITB-Monash Research Academy, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Department of Mechanical and Aerospace Engineering, Monash University, VIC 3800 Australia (Australia); Joardar, Joydip [International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad (India); Singh Raman, R.K. [Department of Mechanical and Aerospace Engineering, Monash University, VIC 3800 Australia (Australia); Department of Chemical Engineering, Monash University, VIC 3800 Australia (Australia); Raja, V.S. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Joshi, S.V. [International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad (India); Parida, S. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India)

    2016-06-25

    Prior studies on synthesis of nanocrystalline elements have discussed the effect of ball milling on lattice parameter, crystallite size, and micro-strain. For elemental milled powders, the anisotropic peak broadening does not change with increasing milling time. However, the effect of alloying addition on the anisotropic behavior of ball milled nanocrystalline powders remains an unexplored area. Here we report the effect of chromium and aluminum addition on the anisotropic behavior of iron in nanocrystalline Fe–20Cr–5Al (wt%) alloy powders synthesized by ball milling. The experimental results show that the anisotropic behavior of iron changes towards isotropic with milling. This change was also correlated to the theoretically calculated anisotropic factor from the change in elastic constant of iron due to milling. Addition of alloying elements exhibited a monotonic rise in the lattice parameter with crystallite size, which was attributed to the excess grain boundary interfacial energy and excess free volume at grain boundaries. Transmission electron microscopy image confirmed the crystallite size and nature of dislocation obtained using modified Williamson-Hall method. - Highlights: • Structural evolution in Fe–20Cr–5Al alloy during ball milling is reported. • Effect of alloying addition on the anisotropic behavior of iron was studied. • Agreement in anisotropic factor calculated theoretically and experimentally.

  19. Anisotropic surface chemistry properties and adsorption behavior of silicate mineral crystals.

    Science.gov (United States)

    Xu, Longhua; Tian, Jia; Wu, Houqin; Fang, Shuai; Lu, Zhongyuan; Ma, Caifeng; Sun, Wei; Hu, Yuehua

    2018-03-07

    Anisotropic surface properties of minerals play an important role in a variety of fields. With a focus on the two most intensively investigated silicate minerals (i.e., phyllosilicate minerals and pegmatite aluminosilicate minerals), this review highlights the research on their anisotropic surface properties based on their crystal structures. Four surface features comprise the anisotropic surface chemistry of minerals: broken bonds, energy, wettability, and charge. Analysis of surface broken bond and energy anisotropy helps to explain the cleavage and growth properties of mineral crystals, and understanding surface wettability and charge anisotropy is critical to the analysis of minerals' solution behavior, such as their flotation performance and rheological properties. In a specific reaction, the anisotropic surface properties of minerals are reflected in the adsorption strengths of reagents on different mineral surfaces. Combined with the knowledge of mineral crushing and grinding, a thorough understanding of the anisotropic surface chemistry properties and the anisotropic adsorption behavior of minerals will lead to the development of effective relational models comprising their crystal structure, surface chemistry properties, and targeted reagent adsorption. Overall, such a comprehensive approach is expected to firmly establish the connection between selective cleavage of mineral crystals for desired surfaces and designing novel reagents selectively adsorbed on the mineral surfaces. As tools to characterize the anisotropic surface chemistry properties of minerals, DLVO theory, atomic force microscopy (AFM), and molecular dynamics (MD) simulations are also reviewed. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Anisotropic spin motive force in multi-layered Dirac fermion system, α-(BEDT-TTF)2I3

    International Nuclear Information System (INIS)

    Kubo, K; Morinari, T

    2015-01-01

    We investigate the anisotropic spin motive force in α-(BEDT-TTF) 2 I 3 , which is a multi-layered massless Dirac fermion system under pressure. Assuming the interlayer antiferromagnetic interaction and the interlayer anisotropic ferromagnetic interaction, we numerically examine the spin ordered state of the ground state using the steepest descent method. The anisotropic interaction leads to the anisotropic spin ordered state. We calculate the spin motive force produced by the anisotropic spin texture. The result quantitatively agrees with the experiment. (paper)

  1. Efficient Modeling and Migration in Anisotropic Media Based on Prestack Exploding Reflector Model and Effective Anisotropy

    KAUST Repository

    Wang, Hui

    2014-05-01

    This thesis addresses the efficiency improvement of seismic wave modeling and migration in anisotropic media. This improvement becomes crucial in practice as the process of imaging complex geological structures of the Earth\\'s subsurface requires modeling and migration as building blocks. The challenge comes from two aspects. First, the underlying governing equations for seismic wave propagation in anisotropic media are far more complicated than that in isotropic media which demand higher computational costs to solve. Second, the usage of whole prestack seismic data still remains a burden considering its storage volume and the existing wave equation solvers. In this thesis, I develop two approaches to tackle the challenges. In the first part, I adopt the concept of prestack exploding reflector model to handle the whole prestack data and bridge the data space directly to image space in a single kernel. I formulate the extrapolation operator in a two-way fashion to remove he restriction on directions that waves propagate. I also develop a generic method for phase velocity evaluation within anisotropic media used in this extrapolation kernel. The proposed method provides a tool for generating prestack images without wavefield cross correlations. In the second part of this thesis, I approximate the anisotropic models using effective isotropic models. The wave phenomena in these effective models match that in anisotropic models both kinematically and dynamically. I obtain the effective models through equating eikonal equations and transport equations of anisotropic and isotropic models, thereby in the high frequency asymptotic approximation sense. The wavefields extrapolation costs are thus reduced using isotropic wave equation solvers while the anisotropic effects are maintained through this approach. I benchmark the two proposed methods using synthetic datasets. Tests on anisotropic Marmousi model and anisotropic BP2007 model demonstrate the applicability of my

  2. Anisotropic wetting characteristics versus roughness on machined surfaces of hydrophilic and hydrophobic materials

    International Nuclear Information System (INIS)

    Liang, Yande; Shu, Liming; Natsu, Wataru; He, Fuben

    2015-01-01

    Graphical abstract: - Highlights: • The aim is to investigate the influence of roughness on anisotropic wetting on machined surfaces. • The relationship between roughness and anisotropic wetting is modeled by thermodynamical analysis. • The effect of roughness on anisotropic wetting on hydrophilic materials is stronger than that on hydrophobic materials. • The energy barrier existing in the direction perpendicular to the lay is one of the main reasons for the anisotropic wetting. • The contact angle in the parallel direction is larger than that in the perpendicular direction. - Abstract: Anisotropic wetting of machined surfaces is widely applied in industries which can be greatly affected by roughness and solid's chemical properties. However, there has not been much work on it. A free-energy thermodynamic model is presented by analyzing geometry morphology of machined surfaces (2-D model surfaces), which demonstrates the influence of roughness on anisotropic wetting. It can be concluded that the energy barrier is one of the main reasons for the anisotropic wetting existing in the direction perpendicular to the lay. In addition, experiments in investigating anisotropic wetting, which was characterized by the static contact angle and droplet's distortion, were performed on machined surfaces with different roughness on hydrophilic and hydrophobic materials. The droplet's anisotropy found on machined surfaces increased with mean slope of roughness profile Kr. It indicates that roughness on anisotropic wetting on hydrophilic materials has a stronger effect than that on hydrophobic materials. Furthermore, the contact angles predicted by the model are basically consistent with the experimentally ones

  3. A 3-D elasticity theory based model for acoustic radiation from multilayered anisotropic plates.

    Science.gov (United States)

    Shen, C; Xin, F X; Lu, T J

    2014-05-01

    A theoretical model built upon three-dimensional elasticity theory is developed to investigate the acoustic radiation from multilayered anisotropic plates subjected to a harmonic point force excitation. Fourier transform technique and stationary phase method are combined to predict the far-field radiated sound pressure of one-side water immersed plate. Compared to equivalent single-layer plate models, the present model based on elasticity theory can differentiate radiated sound pressure between dry-side and wet-side excited cases, as well as discrepancies induced by different layer sequences for multilayered anisotropic plates. These results highlight the superiority of the present theoretical model especially for handling multilayered anisotropic structures.

  4. Anisotropic stress as a signature of nonstandard propagation of gravitational waves.

    Science.gov (United States)

    Saltas, Ippocratis D; Sawicki, Ignacy; Amendola, Luca; Kunz, Martin

    2014-11-07

    We make precise the heretofore ambiguous statement that anisotropic stress is a sign of a modification of gravity. We show that in cosmological solutions of very general classes of models extending gravity-all scalar-tensor theories (Horndeski), Einstein-aether models, and bimetric massive gravity-a direct correspondence exists between perfect fluids apparently carrying anisotropic stress and a modification in the propagation of gravitational waves. Since the anisotropic stress can be measured in a model-independent manner, a comparison of the behavior of gravitational waves from cosmological sources with large-scale-structure formation could, in principle, lead to new constraints on the theory of gravity.

  5. Mixed Boundary Value Problem on Hypersurfaces

    Directory of Open Access Journals (Sweden)

    R. DuDuchava

    2014-01-01

    Full Text Available The purpose of the present paper is to investigate the mixed Dirichlet-Neumann boundary value problems for the anisotropic Laplace-Beltrami equation divC(A∇Cφ=f on a smooth hypersurface C with the boundary Γ=∂C in Rn. A(x is an n×n bounded measurable positive definite matrix function. The boundary is decomposed into two nonintersecting connected parts Γ=ΓD∪ΓN and on ΓD the Dirichlet boundary conditions are prescribed, while on ΓN the Neumann conditions. The unique solvability of the mixed BVP is proved, based upon the Green formulae and Lax-Milgram Lemma. Further, the existence of the fundamental solution to divS(A∇S is proved, which is interpreted as the invertibility of this operator in the setting Hp,#s(S→Hp,#s-2(S, where Hp,#s(S is a subspace of the Bessel potential space and consists of functions with mean value zero.

  6. SPORT MARKETING MIX STRATEGIES

    OpenAIRE

    Alexandru Lucian MIHAI

    2013-01-01

    This paper presents a brief overview of a significant element of the sport marketing management model called the marketing mix. The marketing mix is crucial because it defines the sport business, and much of the sport marketer’s time is spent on various functions within the marketing mix. The marketing mix is the strategic combination of the product, price, place and promotion elements. These elements are typically called the four Ps of marketing. Decisions and strategies for each are importa...

  7. Mixed methods research.

    Science.gov (United States)

    Halcomb, Elizabeth; Hickman, Louise

    2015-04-08

    Mixed methods research involves the use of qualitative and quantitative data in a single research project. It represents an alternative methodological approach, combining qualitative and quantitative research approaches, which enables nurse researchers to explore complex phenomena in detail. This article provides a practical overview of mixed methods research and its application in nursing, to guide the novice researcher considering a mixed methods research project.

  8. Mixing Over Rough Topography

    Science.gov (United States)

    2017-10-25

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Mixing Over Rough Topography Michael C. Gregg APL/UW...OBJECTIVES To understand mixing over rough topography. APPROACH To supplement NRL’s Mixing Over Rough Topography (MORT) measurements over ...to 1) Assess hydraulic control along lines crossing the bank, and 2) Measure turbulent dissipation rates over the bank. WORK COMPLETED The

  9. Anisotropic Characteristics of Turbulence Dissipation in Swirling Flow: A Direct Numerical Simulation Study

    Directory of Open Access Journals (Sweden)

    Xingtuan Yang

    2015-01-01

    Full Text Available This study investigates the anisotropic characteristics of turbulent energy dissipation rate in a rotating jet flow via direct numerical simulation. The turbulent energy dissipation tensor, including its eigenvalues in the swirling flows with different rotating velocities, is analyzed to investigate the anisotropic characteristics of turbulence and dissipation. In addition, the probability density function of the eigenvalues of turbulence dissipation tensor is presented. The isotropic subrange of PDF always exists in swirling flows relevant to small-scale vortex structure. Thus, with remarkable large-scale vortex breakdown, the isotropic subrange of PDF is reduced in strongly swirling flows, and anisotropic energy dissipation is proven to exist in the core region of the vortex breakdown. More specifically, strong anisotropic turbulence dissipation occurs concentratively in the vortex breakdown region, whereas nearly isotropic turbulence dissipation occurs dispersively in the peripheral region of the strong swirling flows.

  10. P-wave ray velocities and the inverse acoustic problem for anisotropic media

    Czech Academy of Sciences Publication Activity Database

    Zel, I. Yu.; Ivankina, T. I.; Levin, D.M.; Lokajíček, Tomáš

    2016-01-01

    Roč. 61, č. 4 (2016), s. 633-639 ISSN 1063-7745 Institutional support: RVO:67985831 Keywords : anisotropic media * P-Wawe velocities * elasticity Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.563, year: 2016

  11. Anisotropic growth mechanism of tungsten diselenide domains using chemical vapor deposition method

    Science.gov (United States)

    Lee, Yoobeen; Jeong, Heekyung; Park, Yi-Seul; Han, Seulki; Noh, Jaegeun; Lee, Jin Seok

    2018-02-01

    Anisotropic transition metal dichalcogenide (TMDC) domains have stimulated a growing interest mainly due to their electronic properties that depend on the size, shape, and edge structures of the domains. In this work, we investigated the anisotropic morphogenesis and edge terminations of tungsten diselenide (WSe2) domains grown on sapphire substrates by chemical vapor deposition (CVD) using tungsten oxide (WO3) and selenium (Se) powders as precursors. We varied the amount of Se powder and growth temperature during the CVD process, which in turn caused variations in the growth mechanism and kinetic energies of precursors. We succeeded in synthesizing hexagonal, square, circular, and triangular anisotropic WSe2 domains. They were characterized using scanning electron microscopy (SEM), Raman spectroscopy, photoluminescence (PL) analyses, and atomic force microscopy (AFM). Furthermore, we proposed the growth mechanism of anisotropic WSe2 domains with different edge terminations based on experimental observations through scanning tunneling microscope (STM).

  12. Predicting sintering deformation of ceramic film constrained by rigid substrate using anisotropic constitutive law

    International Nuclear Information System (INIS)

    Li Fan; Pan Jingzhe; Guillon, Olivier; Cocks, Alan

    2010-01-01

    Sintering of ceramic films on a solid substrate is an important technology for fabricating a range of products, including solid oxide fuel cells, micro-electronic PZT films and protective coatings. There is clear evidence that the constrained sintering process is anisotropic in nature. This paper presents a study of the constrained sintering deformation using an anisotropic constitutive law. The state of the material is described using the sintering strains rather than the relative density. In the limiting case of free sintering, the constitutive law reduces to a conventional isotropic constitutive law. The anisotropic constitutive law is used to calculate sintering deformation of a constrained film bonded to a rigid substrate and the compressive stress required in a sinter-forging experiment to achieve zero lateral shrinkage. The results are compared with experimental data in the literature. It is shown that the anisotropic constitutive law can capture the behaviour of the materials observed in the sintering experiments.

  13. Propagation of S-waves in a non-homogeneous anisotropic ...

    African Journals Online (AJOL)

    homogeneous anisotropic incompressible and initially stressed medium. Analytical analysis reveals that the velocities of the shear waves depend upon the direction of propagation, the anisotropy, the non-homogeneity of the medium and the initial ...

  14. A simple strategy to realize biomimetic surfaces with controlled anisotropic wetting

    Science.gov (United States)

    Wu, Dong; Chen, Qi-Dai; Yao, Jia; Guan, Yong-Chao; Wang, Jian-Nan; Niu, Li-Gang; Fang, Hong-Hua; Sun, Hong-Bo

    2010-02-01

    The study of anisotropic wetting has become one of the most important research areas in biomimicry. However, realization of controlled anisotropic surfaces remains challenging. Here we investigated anisotropic wetting on grooves with different linewidth, period, and height fabricated by laser interference lithography and found that the anisotropy strongly depended on the height. The anisotropy significantly increased from 9° to 48° when the height was changed from 100 nm to 1.3 μm. This was interpreted by a thermodynamic model as a consequence of the increase of free energy barriers versus the height increase. According to the relationship, controlled anisotropic surfaces were rapidly realized by adjusting the grooves' height that was simply accomplished by changing the resin thickness. Finally, the perpendicular contact angle was further enhanced to 131°±2° by surface modification, which was very close to 135°±3° of a common grass leaf.

  15. A study on the effective hydraulic conductivity of an anisotropic porous medium

    International Nuclear Information System (INIS)

    Seong, Kwan Jae

    2002-01-01

    Effective hydraulic conductivity of a statistically anisotropic heterogeneous medium is obtained for steady two-dimensional flows employing stochastic analysis. Flow equations are solved up to second order and the effective conductivity is obtained in a semi-analytic form depending only on the spatial correlation function and the anisotropy ratio of the hydraulic conductivity field, hence becoming a true intrinsic property independent of the flow field. Results are obtained using a statistically anisotropic Gaussian correlation function where the anisotropic is defined as the ratio of integral scales normal and parallel to the mean flow direction. Second order results indicate that the effective conductivity of an anisotropic medium is greater than that of an isotropic one when the anisotropy ratio is less than one and vice versa. It is also found that the effective conductivity has upper and lower bounds of the arithmetic and the harmonic mean conductivities

  16. Anisotropic Hardening Behaviour and Springback of Advanced High-Strength Steels

    Directory of Open Access Journals (Sweden)

    Jaebong Jung

    2017-11-01

    Full Text Available Advanced high-strength steels (AHSSs exhibit large, and sometimes anisotropic, springback recovery after forming. Accurate description of the anisotropic elasto-plastic behaviour of sheet metals is critical for predicting their anisotropic springback behaviour. For some materials, the initial anisotropy is maintained while hardening progresses. However, for other materials, anisotropy changes with hardening. In this work, to account for the evolution of anisotropy of a dual-phase steel, an elastoplastic material constitutive model is developed. In particular, the combined isotropic–kinematic hardening model was modified. Tensile loading–unloading, uniaxial and biaxial tension, and tension–compression tests were conducted along the rolling, diagonal, and transverse directions to measure the anisotropic properties, and the parameters of the proposed constitutive model were determined. For validation, the proposed model was applied to a U-bending process, and the measured springback angles were compared to the predicted ones.

  17. Self-organization of anisotropic and binary colloids in thermo-switchable 1D microconfinement

    NARCIS (Netherlands)

    De Folter, Julius W J; Liu, Ping; Jiang, Lingxiang; Kuijk, Anke; Bakker, Henriëtte E.; Imhof, Arnout; Van Blaaderen, Alfons; Huang, Jianbin; Kegel, Willem K.; Philipse, Albert P.; Petukhov, Andrei V.

    2015-01-01

    Anisotropic and binary colloids self-assemble into a variety of novel supracolloidal structures within the thermo-switchable confinement of molecular microtubes, achieving structuring at multiple length scales and dimensionalities. The multistage self-assembly strategy involving hard colloidal

  18. Tunneling anisotropic magnetoresistance in Co/AIOx/Al tunnel junctions with fcc Co (111) electrodes

    NARCIS (Netherlands)

    Wang, Kai; Tran, T. Lan Ahn; Brinks, Peter; Brinks, P.; Sanderink, Johannes G.M.; Bolhuis, Thijs; van der Wiel, Wilfred Gerard; de Jong, Machiel Pieter

    2013-01-01

    Tunneling anisotropic magnetoresistance (TAMR) has been characterized in junctions comprised of face-centered cubic (fcc) Co (111) ferromagnetic electrodes grown epitaxially on sapphire substrates, amorphous AlOx tunnel barriers, and nonmagnetic Al counterelectrodes. Large TAMR ratios have been

  19. Process chain for fabrication of anisotropic optical functional surfaces on polymer components

    DEFF Research Database (Denmark)

    Li, Dongya; Zhang, Yang; Regi, Francesco

    2017-01-01

    This paper aims to introduce a process chain for fabrication of anisotropic optical functional surfaces on polymer products. Thesurface features under investigation are composed of micro serrated ridges. The scope was to maximize the visible contrast betweenhorizontally orthogonal textured surfaces...

  20. An analytical model of anisotropic low-field electron mobility in wurtzite indium nitride

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shulong; Liu, Hongxia; Song, Xin; Guo, Yulong; Yang, Zhaonian [Xidian University, School of Microelectronics, Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, Xi' an (China)

    2014-03-15

    This paper presents a theoretical analysis of anisotropic transport properties and develops an anisotropic low-field electron analytical mobility model for wurtzite indium nitride (InN). For the different effective masses in the Γ-A and Γ-M directions of the lowest valley, both the transient and steady state transport behaviors of wurtzite InN show different transport characteristics in the two directions. From the relationship between velocity and electric field, the difference is more obvious when the electric field is low in the two directions. To make an accurate description of the anisotropic transport properties under low field, for the first time, we present an analytical model of anisotropic low-field electron mobility in wurtzite InN. The effects of different ionized impurity scattering models on the low-field mobility calculated by Monte Carlo method (Conwell-Weisskopf and Brooks-Herring method) are also considered. (orig.)