Sample records for theory torsional angular

  1. Coupling a small torsional oscillator to large optical angular momentum

    NASA Astrophysics Data System (ADS)

    Shi, Hao; Bhattacharya, Mishkatul

    2013-05-01

    We propose a new optomechanical system to achieve torsional optomechanics. Our system is composed of a windmill-shaped dielectric optically trapped within a cavity interacting with Laguerre-Gaussian cavity modes with both angular and radial nodes. Compared to existing configurations, our proposal enables small mechanical oscillators to interact with the in-principle unlimited orbital angular momentum that can be carried by a single photon, and therefore allows the generation of scalable optomechanical coupling. We propose a new optomechanical system to achieve torsional optomechanics. Our system is composed of a windmill-shaped dielectric optically trapped within a cavity interacting with Laguerre-Gaussian cavity modes with both angular and radial nodes. Compared to existing configurations, our proposal enables small mechanical oscillators to interact with the in-principle unlimited orbital angular momentum that can be carried by a single photon, and therefore allows the generation of scalable optomechanical coupling. Supported by Research Corporation for Science Advancement.

  2. 35. VERTICAL AND TORSIONAL MOTION FROM EAST TOWER SHOWING ANGULAR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    35. VERTICAL AND TORSIONAL MOTION FROM EAST TOWER SHOWING ANGULAR DISTORTION APPROACHING 45 DEGREES WITH LAMP POSTS APPEARING TO BE AT EIGHT ANGLES, 7 NOVEMBER 1940, FROM 16MN FILM SHOT BY PROFESSOR F.B. FARQUHARSON, UNIVERSITY OF WASHINGTON. (LABORATORY STUDIES ON THE TACOMA NARROWS BRIDGE, AT UNIVERSITY OF WASHINGTON SEATTLE: UNIVERSITY OF WASHINGTON, DEPARTMENT OF CIVIL ENGINEERING, 1941) - Tacoma Narrows Bridge, Spanning Narrows at State Route 16, Tacoma, Pierce County, WA

  3. New constraints in dynamical torsion theory

    E-print Network

    M. O. Katanaev

    2001-01-14

    The most general Lagrangian for dynamical torsion theory quadratic in curvature and torsion is considered. We impose two simple and physically reasonable constraints on the solutions of the equations of motion: (i) there must be solutions with zero curvature and nontrivial torsion and (ii) there must be solutions with zero torsion and non covariantly constant curvature. The constraints reduce the number of independent coupling constants from ten to five. The resulting theory contains Einstein's general relativity and Weitzenbock's absolute parallelism theory as the two sectors.

  4. Linearized Torsion Waves in a Tensor-Tensor Theory of Gravity

    E-print Network

    Chih-Hung Wang

    2007-12-12

    We investigate a linearized tensor-tensor theory of gravity with torsion and a perturbed torsion wave solution is discovered in background Minkowski spacetime with zero torsion. Furthermore, gauge transformations of any perturbed tensor field are derived in general background non-Riemannian geometries. By calculating autoparallel deviations, both longitudinal and transverse polarizations of the torsion wave are discovered.

  5. On discrete symmetries and torsion homology in F-theory

    NASA Astrophysics Data System (ADS)

    Mayrhofer, Christoph; Palti, Eran; Till, Oskar; Weigand, Timo

    2015-06-01

    We study the relation between discrete gauge symmetries in F-theory compactifications and torsion homology on the associated Calabi-Yau manifold. Focusing on the simplest example of a symmetry, we show that there are two physically distinct ways that such a discrete gauge symmetry can arise. First, compactifications of M-Theory on Calabi-Yau threefolds which support a genus-one fibration with a bi-section are known to be dual to six-dimensional F-theory vacua with a gauge symmetry. We show that the resulting five-dimensional theories do not have a symmetry but that the latter emerges only in the F-theory decompactification limit. Accordingly the genus-one fibred Calabi-Yau manifolds do not exhibit torsion in homology. Associated to the bi-section fibration is a Jacobian fibration which does support a section. Compactifying on these related but distinct varieties does lead to a symmetry in five dimensions and, accordingly, we find explicitly an associated torsion cycle. We identify the expected particle and membrane system of the discrete symmetry in terms of wrapped M2 and M5 branes and present a field-theory description of the physics for both cases in terms of circle reductions of six-dimensional theories. Our results and methods generalise straightforwardly to larger discrete symmetries and to four-dimensional compactifications.

  6. Can a macroscopic gyroscope feel torsion

    NASA Technical Reports Server (NTRS)

    Stoeger, W. R.; Yasskin, P. B.

    1979-01-01

    We demonstrate that for a large class of Lagrangian-based torsion theories a macroscopic gyroscope is insensitive to the torsion field: there can be no coupling of the torsion to the gyroscope's angular momentum of rotation. To detect torsion a polarized system with a net elementary particle spin is needed. These conclusions are evident from the conservation laws, which form the basis for deriving the equations of motion.

  7. Propagation equations for test bodies with spin and rotation in theories of gravity with torsion

    Microsoft Academic Search

    Philip Yasskin; William Stoeger

    1980-01-01

    We generalize the Papapetrou equations by deriving propagation equations for the energy-momentum and angular momentum of a test body which has both elementary-particle spin and macroscopic rotation and which is moving in background metric and torsion fields. Our results show that the torsion couples to spin but not to rotation. Thus a rotating test body with no net spin will

  8. Constraining torsion with Gravity Probe B

    SciTech Connect

    Mao Yi; Guth, Alan H.; Cabi, Serkan [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Tegmark, Max [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); MIT Kavli Institute for Astrophysics and Space Research, Cambridge, Massachusetts 02139 (United States)

    2007-11-15

    It is well-entrenched folklore that all torsion gravity theories predict observationally negligible torsion in the solar system, since torsion (if it exists) couples only to the intrinsic spin of elementary particles, not to rotational angular momentum. We argue that this assumption has a logical loophole which can and should be tested experimentally, and consider nonstandard torsion theories in which torsion can be generated by macroscopic rotating objects. In the spirit of action=reaction, if a rotating mass like a planet can generate torsion, then a gyroscope would be expected to feel torsion. An experiment with a gyroscope (without nuclear spin) such as Gravity Probe B (GPB) can test theories where this is the case. Using symmetry arguments, we show that to lowest order, any torsion field around a uniformly rotating spherical mass is determined by seven dimensionless parameters. These parameters effectively generalize the parametrized post-Newtonian formalism and provide a concrete framework for further testing Einstein's general theory of relativity (GR). We construct a parametrized Lagrangian that includes both standard torsion-free GR and Hayashi-Shirafuji maximal torsion gravity as special cases. We demonstrate that classic solar system tests rule out the latter and constrain two observable parameters. We show that Gravity Probe B is an ideal experiment for further constraining nonstandard torsion theories, and work out the most general torsion-induced precession of its gyroscope in terms of our torsion parameters.

  9. De Sitter spacetimes with torsion in the model of dS gauge theory of gravity

    E-print Network

    Chao-Guang Huang; Meng-Sen Ma

    2009-10-08

    In the model of de Sitter gauge theory of gravity, the empty homogenous and isotropic spacetimes with constant curvature scalar and nonvanishing homogenous and isotropic torsion must have de Sitter metrics. The static de Sitter spacetime with static, O(3)-symmetric, vector torsion is the only spherically symmetric, vacuum solution with the metric of the form $g_{\\mu\

  10. Theory of Angular Momentum This chapter is concerned with a systematic treatment of angular momen-

    E-print Network

    Satija, Indu

    153 CHAPTER 3 Theory of Angular Momentum This chapter is concerned with a systematic treatment to illustrate the noncommutativity of finite rotations. #12;154 155Theory of Angular NlOmentUm To be definite-plane, as viewed from the positi z-side. If we associate a right-handed screw with such a rotation, a rotation

  11. The exterior gravitational field of a charged spinning source in the poincaré gauge theory: A Kerr-newman metric with dynamic torsion

    Microsoft Academic Search

    Peter Baekler; Metin Gürses; Friedrich W. Hehl; J. Dermott McCrea

    1988-01-01

    We present a new exact solution of the Poincaré gauge theory, namely a charged Kerr-NUT metric with an effective cosmological constant which is consistently coupled to a dynamic torsion field. The solution is given in terms of an orthonormal basis in Boyer-Lindquist coordinates and depends on the constants m0 (mass), j0 (angular momentum), q0 (electric charge), and n0 (NUT parameter).

  12. Parallel spinors and connections with skewsymmetric torsion in string theory \\Lambda

    E-print Network

    Friedrich, Thomas

    Parallel spinors and connections with skew­symmetric torsion in string theory \\Lambda Thomas is of importance in string theory, since they are associated with some string solitons (BPS solitons) [42­ plications in the exploration of perturbative and non­perturbative properties of string theory. An important

  13. Spontaneous Generation of Angular Momentum in Holographic Theories

    E-print Network

    Liu, Hong

    The Schwarzschild black two-brane in four-dimensional anti–de Sitter space is dual to a finite temperature state in three-dimensional conformal field theory. We show that the solution acquires a nonzero angular momentum ...

  14. Dynamical torsion in a gravitational theory coupled to first-order twist-tensor matter fields

    SciTech Connect

    Rosenbaum, M.; Ryan, M.P. Jr.; Urrutia, L.F.; Luehr, C.P.

    1982-08-15

    A gravity-matter theory is developed using twist tensors as bona fide matter fields which are minimally coupled to gravitation by means of a first-order matter Lagrangian. The main features of the theory are (i) torsion is generated dynamically by the matter fields and (ii) torsion is coupled to a scalar field via a nonzero spin density which arises from the first-order matter Lagrangian but nevertheless provides a vanishing integrated spin for the scalar field. The equations of motion for the fields are given and some solutions are discussed.

  15. Self-gravitating spherically symmetric solutions in scalar-torsion theories

    NASA Astrophysics Data System (ADS)

    Kofinas, Georgios; Papantonopoulos, Eleftherios; Saridakis, Emmanuel N.

    2015-05-01

    We study spherically symmetric solutions in scalar-torsion gravity theories in which a scalar field is coupled to torsion with a derivative coupling. We obtain the general field equations from which we extract a decoupled master equation, the solution of which leads to the specification of all other unknown functions. We first obtain an exact solution which represents a new wormholelike solution dressed with a regular scalar field. Then, we find large distance linearized spherically symmetric solutions in which the space asymptotically is anti-de Sitter.

  16. Brans-Dicke theory of gravity with torsion: A possible solution of the $?$-problem

    E-print Network

    Yu-Huei Wu; Chih-Hung Wang

    2012-11-15

    We study the Brans-Dicke theory of gravity in Riemann-Cartan space-times, and obtain general torsion solutions, which are completely determined by Brans-Dicke scalar field $\\Phi$, in the false vacuum energy dominated epoch. The substitution of the torsion solutions back to our action gives the original Brans-Dicke action with $\\Phi$-dependent Brans-Dicke parameter $\\omega(\\Phi)$. The evolution of $\\omega(\\Phi)$ during the inflation is studied and it is found that $\\omega$ approaches to infinity at the end of inflation. This may solve the $\\omega$-problem in the extended inflation model.

  17. Torsional oscillations of neutron stars in scalar-tensor theory of gravity

    E-print Network

    Hector O. Silva; Hajime Sotani; Emanuele Berti; Michael Horbatsch

    2014-10-09

    We study torsional oscillations of neutron stars in the scalar-tensor theory of gravity using the relativistic Cowling approximation. We compute unperturbed neutron star models adopting realistic equations of state for the neutron star's core and crust. For scalar-tensor theories that allow for spontaneous scalarization, the crust thickness can be significantly smaller than in general relativity. We derive the perturbation equation describing torsional oscillations in scalar-tensor theory, and we solve the corresponding eigenvalue problem to find the oscillation frequencies. The fundamental mode (overtone) frequencies become smaller (larger) than in general relativity for scalarized stellar models. Torsional oscillation frequencies may yield information on the crust microphysics if microphysics effects are not degenerate with strong-gravity effects, such as those due to scalarization. To address this issue, we consider two different models for the equation of state of the crust and we look at the effects of electron screening. The effect of scalarization on torsional oscillation frequencies turns out to be smaller than uncertainties in the microphysics for all spontaneous scalarization models allowed by binary pulsar observations. Our study shows that the observation of quasi-periodic oscillations (QPOs) following giant flares can be used to constrain the microphysics of neutron star crusts, whether spontaneous scalarization occurs or not.

  18. Atomic and Molecular Quantum Theory Course Number: C561 18 Theory of Angular Momentum

    E-print Network

    Iyengar, Srinivasan S.

    Atomic and Molecular Quantum Theory Course Number: C561 18 Theory of Angular Momentum 1. Why do we Quantum Theory Course Number: C561 5. What if we consider the simplest molecular system: the hy- drogen (instructor) #12;Atomic and Molecular Quantum Theory Course Number: C561 11. This is the approach we will use

  19. A Quantum Field Theory Twist to Photon Angular Momentum

    E-print Network

    G. F. Calvo; A. Picon; E. Bagan

    2005-09-06

    A quantum field theory approach is put forward to generalize the concept of classical spatial light beams carrying orbital angular momentum to the single-photon level. This quantization framework is carried out both in the paraxial and nonparaxial regimes. Upon extension to the optical phase space, closed-form expressions are found for a photon Wigner representation describing transformations on the orbital Poincare sphere of unitarily related families of paraxial spatial modes.

  20. Spontaneous generation of angular momentum in holographic theories.

    PubMed

    Liu, Hong; Ooguri, Hirosi; Stoica, Bogdan; Yunes, Nicolás

    2013-05-24

    The Schwarzschild black two-brane in four-dimensional anti-de Sitter space is dual to a finite temperature state in three-dimensional conformal field theory. We show that the solution acquires a nonzero angular momentum density when a gravitational Chern-Simons coupling is turned on in the bulk, even though the solution is not modified. A similar phenomenon is found for the Reissner-Nordström black two-brane with axionic coupling to the gauge field. We discuss interpretation of this phenomenon from the point of view of the boundary three-dimensional conformal field theory. PMID:23745857

  1. de Sitter gauge theory of gravity: an alternative torsion cosmology

    NASA Astrophysics Data System (ADS)

    Ao, Xi-Chen; Li, Xin-Zhou

    2011-10-01

    A new cosmological model based on the de Sitter gauge theory (dSGT) is studied in this paper. By some transformations, we find, in the dust universe, the cosmological equations of dSGT could form an autonomous system. We conduct dynamics analysis to this system, and find 9 critical points, among which there exist one positive attractor and one negative attractor. The positive attractor shows us that our universe will enter a exponential expansion phase in the end, which is similar to the conclusion of ?CDM. We also carry out some numerical calculations, which confirms the conclusion of dynamics analysis. Finally, we fit the model parameter and initial values to the Union 2 SNIa dataset, present the confidence contour of parameters and obtain the best-fit values of parameters of dSGT.

  2. Standard electroweak interactions in gravitational theory with chameleon field and torsion

    NASA Astrophysics Data System (ADS)

    Ivanov, A. N.; Wellenzohn, M.

    2015-04-01

    We propose a version of a gravitational theory with a torsion field, induced by the chameleon field. Following Hojman et al. [Phys. Rev. D 17, 3141 (1976)], the results obtained in Phys. Rev. D 90, 045040 (2014) are generalized by extending Einstein gravity to Einstein-Cartan gravity with a torsion field as a gradient of the chameleon field through a modification of the local gauge invariance of minimal coupling in the Weinberg-Salam electroweak model. The contributions of the chameleon (torsion) field to the observables of electromagnetic and weak processes are calculated. Since in our approach the chameleon-photon coupling constant ?? is equal to the chameleon-matter coupling constant ? , i.e., ??=? , the experimental constraints on ? —obtained in terrestrial laboratories by T. Jenke et al. [Phys. Rev. Lett. 112, 115105 (2014)] and by H. Lemmel et al. [Phys. Lett. B 743, 310 (2015)]—can be used for the analysis of astrophysical sources of chameleons, proposed by C. Burrage et al. [Phys. Rev. D 79, 044028 (2009)], A.-C. Davis et al. [Phys. Rev. D 80, 064016 (2009)], and in references therein, where chameleons induce photons because of direct chameleon-photon transitions in the magnetic fields.

  3. Standard Electroweak Interactions in Gravitational Theory with Chameleon Field and Torsion

    E-print Network

    A. N. Ivanov; M. Wellenzohn

    2015-04-22

    We propose a version of a gravitational theory with the torsion field, induced by the chameleon field. Following Hojman et al. Phys. Rev. D17, 3141 (1976) the results, obtained in Phys. Rev. D90, 045040 (2014), are generalised by extending the Einstein gravity to the Einstein-Cartan gravity with the torsion field as a gradient of the chameleon field through a modification of local gauge invariance of minimal coupling in the Weinberg-Salam electroweak model. The contributions of the chameleon (torsion) field to the observables of electromagnetic and weak processes are calculated. Since in our approach the chameleon-photon coupling constant beta_(gamma) is equal to the chameleon-matter coupling constant beta, i.e. beta_(gamma) = beta, the experimental constraints on beta, obtained in terrestrial laboratories by T. Jenke et al. (Phys. Rev. Lett. 112, 115105 (2014)) and by H. Lemmel et al. (Phys. Lett. B743, 310 (2015)), can be used for the analysis of astrophysical sources of chameleons, proposed by C. Burrage et al. (Phys. Rev. D79, 044028 (2009)), A.-Ch. Davis et al. (Phys. Rev. D80, 064016 (2009), and in references therein, where chameleons induce photons because of direct chameleon-photon transitions in the magnetic fields.

  4. Lagrangian theory of the motion of spinning particles in torsion gravitational theories

    Microsoft Academic Search

    Sergio Hojman

    1978-01-01

    The (second-order differential) equations of motion of spinning test particles (tops) are derived from a variational principle in a given gravitational background defined by a Riemannian metric and a torsion tensor. The mass and (magnitude of) the spin of the top are conserved. There exists a Regge trajectory linking the mass and the spin of the top. Constants of the

  5. Spin and orbital angular momentum in gauge theories (I): QED and determination of the angular momentum density

    E-print Network

    X. S. Chen; X. F. Lü; W. M. Sun; F. Wang; T. Goldman

    2007-09-23

    This two-paper series addresses and fixes the long-standing gauge invariance problem of angular momentum in gauge theories. This QED part reveals: 1) The spin and orbital angular momenta of electrons and photons can all be consistently defined gauge invariantly. 2) These gauge-invariant quantities can be conveniently computed via the canonical, gauge-dependent operators (e.g, $\\psi ^\\dagger \\vec x \\times\\frac 1i \\vec \

  6. Mordell-Weil Torsion and the Global Structure of Gauge Groups in F-theory

    E-print Network

    Christoph Mayrhofer; David R. Morrison; Oskar Till; Timo Weigand

    2014-06-19

    We study the global structure of the gauge group $G$ of F-theory compactified on an elliptic fibration $Y$. The global properties of $G$ are encoded in the torsion subgroup of the Mordell-Weil group of rational sections of $Y$. Generalising the Shioda map to torsional sections we construct a specific integer divisor class on $Y$ as a fractional linear combination of the resolution divisors associated with the Cartan subalgebra of $G$. This divisor class can be interpreted as an element of the refined coweight lattice of the gauge group. As a result, the spectrum of admissible matter representations is strongly constrained and the gauge group is non-simply connected. We exemplify our results by a detailed analysis of the general elliptic fibration with Mordell-Weil group $\\mathbb Z_2$ and $\\mathbb Z_3$ as well as a further specialization to $\\mathbb Z \\oplus \\mathbb Z_2$. Our analysis exploits the representation of these fibrations as hypersurfaces in toric geometry.

  7. Semiclassical complex angular momentum theory and Padé reconstruction for resonances, rainbows, and reaction thresholds

    NASA Astrophysics Data System (ADS)

    Sokolovski, D.; Msezane, A. Z.

    2004-09-01

    A semiclassical complex angular momentum theory, used to analyze atom-diatom reactive angular distributions, is applied to several well-known potential (one-particle) problems. Examples include resonance scattering, rainbow scattering, and the Eckart threshold model. Padé reconstruction of the corresponding matrix elements from the values at physical (integral) angular momenta and properties of the Padé approximants are discussed in detail.

  8. Semiclassical complex angular momentum theory and Pade reconstruction for resonances, rainbows, and reaction thresholds

    SciTech Connect

    Sokolovski, D. [School of Mathematics and Physics, Queen's University of Belfast, Belfast, BT7 1NN (United Kingdom); Msezane, A.Z. [Department of Physics and Center for Theoretical Studies of Physical Systems, Clark Atlanta University, Atlanta, Georgia 30314 (United States)

    2004-09-01

    A semiclassical complex angular momentum theory, used to analyze atom-diatom reactive angular distributions, is applied to several well-known potential (one-particle) problems. Examples include resonance scattering, rainbow scattering, and the Eckart threshold model. Pade reconstruction of the corresponding matrix elements from the values at physical (integral) angular momenta and properties of the Pade approximants are discussed in detail.

  9. Covariant differential identities and conservation laws in metric-torsion theories of gravitation. II. Manifestly generally covariant theories

    NASA Astrophysics Data System (ADS)

    Lompay, Robert R.; Petrov, Alexander N.

    2013-10-01

    The present paper continues the work of Lompay and Petrov [J. Math. Phys. 54, 062504 (2013)] where manifestly covariant differential identities and conserved quantities in generally covariant metric-torsion theories of gravity of the most general type have been constructed. Here, we study these theories presented more concretely, setting that their Lagrangians {L} are manifestly generally covariant scalars: algebraic functions of contractions of tensor functions and their covariant derivatives. It is assumed that Lagrangians depend on metric tensor g, curvature tensor R, torsion tensor T and its first {{nabla }}{T} and second {{nabla }}{{nabla }}{T} covariant derivatives, besides, on an arbitrary set of other tensor (matter) fields {\\varphi } and their first {{nabla }}{\\varphi } and second {{nabla }}{{nabla }}{\\varphi } covariant derivatives: {L}= {L}({g},{R}; {T},{{nabla }}{T},{{nabla }}{{nabla }}{T}; {\\varphi },{{nabla }}{\\varphi },{{nabla }}{{nabla }}{\\varphi }). Thus, both the standard minimal coupling with the Riemann-Cartan geometry and non-minimal coupling with the curvature and torsion tensors are considered. The studies and results are as follow: (a) A physical interpretation of the Noether and Klein identities is examined. It was found that they are the basis for constructing equations of balance of energy-momentum tensors of various types (canonical, metrical, and Belinfante symmetrized). The equations of balance are presented. (b) Using the generalized equations of balance, new (generalized) manifestly generally covariant expressions for canonical energy-momentum and spin tensors of the matter fields are constructed. In the cases, when the matter Lagrangian contains both the higher derivatives and non-minimal coupling with curvature and torsion, such generalizations are non-trivial. (c) The Belinfante procedure is generalized for an arbitrary Riemann-Cartan space. (d) A more convenient in applications generalized expression for the canonical superpotential is obtained. (e) A total system of equations for the gravitational fields and matter sources are presented in the form more naturally generalizing the Einstein-Cartan equations with matter. This result, being a one of the more important results itself, is to be also a basis for constructing physically sensible conservation laws and their applications.

  10. Parallel spinors and connections with skew-symmetric torsion in string theory

    Microsoft Academic Search

    Thomas Friedrich; Stefan Ivanov

    2001-01-01

    We describe all almost contact metric, almost hermitian and $G_2$-structures admitting a connection with totally skew-symmetric torsion tensor, and prove that there exists at most one such connection. We investigate its torsion form, its Ricci tensor, the Dirac operator and the $\\\

  11. Maxwell Field with Torsion

    NASA Astrophysics Data System (ADS)

    Fresneda, R.; Baldiotti, M. C.; Pereira, T. S.

    2015-06-01

    We propose a gauge-invariant model of propagating torsion which couples to the Maxwell field and to charged particles. As a result, we have an Abelian gauge-invariant action leading to a theory with nonzero torsion consistent with available experimental data, which can be used to establish a lower bound for our new coupling parameter.

  12. Covariant differential identities and conservation laws in metric-torsion theories of gravitation. I. General consideration

    NASA Astrophysics Data System (ADS)

    Lompay, Robert R.; Petrov, Alexander N.

    2013-06-01

    Arbitrary diffeomorphically invariant metric-torsion theories of gravity are considered. It is assumed that Lagrangians of such theories contain derivatives of field variables (tensor densities of arbitrary ranks and weights) up to a second order only. The generalized Klein-Noether methods for constructing manifestly covariant identities and conserved quantities are developed. Manifestly covariant expressions are constructed without including auxiliary structures like a background metric. In the Riemann-Cartan space, the following manifestly generally covariant results are presented: (a) The complete generalized system of differential identities (the Klein-Noether identities) is obtained. (b) The generalized currents of three types depending on an arbitrary vector field displacements are constructed: they are the canonical Noether current, symmetrized Belinfante current, and identically conserved Hilbert-Bergmann current. In particular, it is stated that the symmetrized Belinfante current does not depend on divergences in the Lagrangian. (c) The generalized boundary Klein theorem (third Noether theorem) is proved. (d) The construction of the generalized superpotential is presented in detail, and questions related to its ambiguities are analyzed.

  13. Theory for noise of propellers in angular inflow with parametric studies and experimental verification

    Microsoft Academic Search

    Donald B. Hanson; David J. Parzych

    1993-01-01

    This report presents the derivation of a frequency domain theory and working equations for radiation of propeller harmonic noise in the presence of angular inflow. In applying the acoustic analogy, integration over the tangential coordinate of the source region is performed numerically, permitting the equations to be solved without approximation for any degree of angular inflow. Inflow angle is specified

  14. Kinematics-free angular momentum trajectories. I. Theory and phenomenology

    Microsoft Academic Search

    Robert Leacock

    1979-01-01

    In the main part of this paper it is shown how to define other complex angular momentum trajectories which are related to, but distinct from, the usual Regge trajectory ..cap alpha... One of these other trajectories, called here ..gamma.., is a zero of a function Y (which is essentially the cotangent of the scattering phase shift for physical values of

  15. Kinematics-free angular momentum trajectories. I. Theory and phenomenology

    Microsoft Academic Search

    Robert A. Leacock

    1979-01-01

    In the main part of this paper it is shown how to define other complex angular momentum trajectories which are related to, but distinct from, the usual Regge trajectory alpha. One of these other trajectories, called here gamma, is a zero of a function Y (which is essentially the cotangent of the scattering phase shift for physical values of the

  16. Interacting spin 0 fields with torsion via Duffin-Kemmer-Petiau theory

    E-print Network

    J. T. Lunardi; B. M. Pimentel; R. G. Teixeira

    2002-03-20

    Here we study the behaviour of spin 0 sector of the DKP field in spaces with torsion. First we show that in a Riemann-Cartan manifold the DKP field presents an interaction with torsion when minimal coupling is performed, contrary to the behaviour of the KG field, a result that breaks the usual equivalence between the DKP and the KG fields. Next we analyse the case of Teleparallel Equivalent of General Relativity Weitzenbock manifold, showing that in this case there is a perfect agreement between KG and DKP fields. The origins of both results are also discussed.

  17. Emergent Gravity and Torsion: String Theory Without String Theory, Why the Cosmic Dark Energy Is So Small

    E-print Network

    Jack Sarfatti

    2007-07-11

    A surprisingly simple holographic explanation for the low dark energy density is suggested. I derive the Einstein-Cartan disclination curvature tetrads and the physically independent dislocation torsion gap spin connections from an "M-Matrix" of non-closed Cartan 1-forms made from 8 Goldstone phase 0-forms of the vacuum ODLRO condensate inflation field in which the non-compact 10-parameter Poincare symmetry group is locally gauged for all invariant matter field actions. Quantum gravity zero point vacuum fluctuations should be renormalizable at the spin 1 tetrad level where there is a natural scale-dependent holographic dimensionless coupling (hG/\\zpf/c^3)^1/3 ~ (Bekenstein BITS)^-1/3. The spacetime tetrad rotation coefficients play the same role as do the Lie algebra structure constants in internal symmetry spin 1 Yang-Mills local gauge theories. This suggests an intuitively pleasing natural "organizing idea" now missing in superstring theory. It is then clear why supersymmetry must break in order for our pocket universe to come into being with a small w = -1 negative pressure zero point exotic vacuum dark energy density. Just as the Michelson-Morley experiment gave a null result, this model predicts that the Large Hadron Collider will never find any viable on-mass-shell dark matter exotic particles able to explain Omega(DM) ~ 0.23 as a matter of fundamental principle, neither will any other conceivable dark matter detector because dark matter forming galactic halos et-al is entirely virtual exotic vacuum w = - 1 with positive irreducibly random quantum zero point pressure that mimics w = 0 CDM in its gravity lensing and all effects that we can observe from afar.

  18. A Torsional Topological Invariant

    E-print Network

    H. T Nieh

    2013-09-04

    Curvature and torsion are the two tensors characterizing a general Riemannian spacetime. In Einstein's general theory of gravitation, with torsion postulated to vanish and the affine connection identified to the Christoffel symbol, only the curvature tensor plays the central role. For such a purely metric geometry, two well-known topological invariants, namely the Euler class and the Pontryagin class, are useful in characterizing the topological properties of the spacetime. From a gauge theory point of view, and especially in the presence of spin, torsion naturally comes into play, and the underlying spacetime is no longer purely metric. We describe a torsional topological invariant, discovered in 1982, that has now found increasing usefulness in recent developments.

  19. a Torsional Topological Invariant

    NASA Astrophysics Data System (ADS)

    Nieh, H. T.

    2008-12-01

    Curvature and torsion are the two tensors characterizing a general Riemannian space-time. In Einstein's general theory of gravitation, with torsion postulated to vanish and the affine connection identified to the Christoffel symbol, only the curvature tensor plays the central role. For such a purely metric geometry, two well-known topological invariants, namely the Euler class and the Pontryagin class, are useful in characterizing the topological properties of the space-time. From a gauge theory point of view, and especially in the presence of spin, torsion naturally comes into play, and the underlying space-time is no longer purely metric. We describe a torsional topological invariant, discovered in 1982, that has now found increasing usefulness in recent developments.

  20. Trace Formulae, Zeta Functions, Congruences and Reidemeister Torsion in Nielsen Theory

    Microsoft Academic Search

    Alexander Fel'shtyn; Richard Hill

    1998-01-01

    In this paper we prove trace formulae for the Reidemeister number of a group endomorphism. This result implies the rationality of the Reidemeister zeta function in the following cases: the group is a direct product of a finite group and a finitely generated Abelian group; the group is finitely generated, nilpotent and torsion free. We continue to study analytical properties

  1. Theory of angular dispersive imaging hard x-ray spectrographs

    E-print Network

    Shvyd'ko, Yuri

    2015-01-01

    A spectrograph is an optical instrument that disperses photons of different energies into distinct directions and space locations, and images photon spectra on a position-sensitive detector. Spectrographs consist of collimating, angular dispersive, and focusing optical elements. Bragg reflecting crystals arranged in an asymmetric scattering geometry are used as the dispersing elements. A ray-transfer matrix technique is applied to propagate x-rays through the optical elements. Several optical designs of hard x-ray spectrographs are proposed and their performance is analyzed. Spectrographs with an energy resolution of 0.1 meV and a spectral window of imaging up to a few tens of meVs are shown to be feasible for inelastic x-ray scattering (IXS) spectroscopy applications. In another example, a spectrograph with a 1-meV spectral resolution and 85-meV spectral window of imaging is considered for Cu K-edge resonant IXS (RIXS).

  2. ANGULAR MOMENTUM TRANSPORT BY ACOUSTIC MODES GENERATED IN THE BOUNDARY LAYER. I. HYDRODYNAMICAL THEORY AND SIMULATIONS

    SciTech Connect

    Belyaev, Mikhail A.; Rafikov, Roman R.; Stone, James M., E-mail: rrr@astro.princeton.edu [Department of Astrophysical Sciences, Princeton University, Ivy Lane, Princeton, NJ 08540 (United States)

    2013-06-10

    The nature of angular momentum transport in the boundary layers of accretion disks has been one of the central and long-standing issues of accretion disk theory. In this work we demonstrate that acoustic waves excited by supersonic shear in the boundary layer serve as an efficient mechanism of mass, momentum, and energy transport at the interface between the disk and the accreting object. We develop the theory of angular momentum transport by acoustic modes in the boundary layer, and support our findings with three-dimensional hydrodynamical simulations, using an isothermal equation of state. Our first major result is the identification of three types of global modes in the boundary layer. We derive dispersion relations for each of these modes that accurately capture the pattern speeds observed in simulations to within a few percent. Second, we show that angular momentum transport in the boundary layer is intrinsically nonlocal, and is driven by radiation of angular momentum away from the boundary layer into both the star and the disk. The picture of angular momentum transport in the boundary layer by waves that can travel large distances before dissipating and redistributing angular momentum and energy to the disk and star is incompatible with the conventional notion of local transport by turbulent stresses. Our results have important implications for semianalytical models that describe the spectral emission from boundary layers.

  3. Complex angular momentum analysis in axiomatic quantum field theory

    Microsoft Academic Search

    J. Bros; G. A. Viano

    In this paper, we wish to present a missing item in the list of analyticity properties rigorously derived from the axioms of Quantum Field Theory (Q.F.T.), part of which served as a basis for the numerous results on relativistic scattering amplitudes, due to the ingenuity of Andr~ Martin. This missing item, which concerns the introduction of analyticity with respect to

  4. Second order classical perturbation theory for atom surface scattering: Analysis of asymmetry in the angular distribution

    SciTech Connect

    Zhou, Yun, E-mail: zhou.yun.x@gmail.com; Pollak, Eli, E-mail: eli.pollak@weizmann.ac.il [Chemical Physics Department, Weizmann Institute of Science, 76100 Rehovot (Israel)] [Chemical Physics Department, Weizmann Institute of Science, 76100 Rehovot (Israel); Miret-Artés, Salvador, E-mail: s.miret@iff.csic.es [Instituto de Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain)] [Instituto de Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain)

    2014-01-14

    A second order classical perturbation theory is developed and applied to elastic atom corrugated surface scattering. The resulting theory accounts for experimentally observed asymmetry in the final angular distributions. These include qualitative features, such as reduction of the asymmetry in the intensity of the rainbow peaks with increased incidence energy as well as the asymmetry in the location of the rainbow peaks with respect to the specular scattering angle. The theory is especially applicable to “soft” corrugated potentials. Expressions for the angular distribution are derived for the exponential repulsive and Morse potential models. The theory is implemented numerically to a simplified model of the scattering of an Ar atom from a LiF(100) surface.

  5. Crystal Field Theory and the Angular Overlap Model Applied to Hydrides of Main Group Elements.

    ERIC Educational Resources Information Center

    Moore, E. A.

    1990-01-01

    Described is how crystal field theory and the angular overlap model can be applied to very simple molecules which can then be used to introduce such concepts as bonding orbitals, MO diagrams, and Walsh diagrams. The main-group compounds are used as examples and a switch to the transition metal complexes. (KR)

  6. Angular momentum evolution of young low-mass stars and brown dwarfs: observations and theory

    E-print Network

    Bouvier, J; Mohanty, S; Scholz, A; Stassun, K G; Zanni, C

    2013-01-01

    This chapter aims at providing the most complete review of both the emerging concepts and the latest observational results regarding the angular momentum evolution of young low-mass stars and brown dwarfs. In the time since Protostars & Planets V, there have been major developments in the availability of rotation period measurements at multiple ages and in different star-forming environments that are essential for testing theory. In parallel, substantial theoretical developments have been carried out in the last few years, including the physics of the star-disk interaction, numerical simulations of stellar winds, and the investigation of angular momentum transport processes in stellar interiors. This chapter reviews both the recent observational and theoretical advances that prompted the development of renewed angular momentum evolution models for cool stars and brown dwarfs. While the main observational trends of the rotational history of low mass objects seem to be accounted for by these new models, a n...

  7. Torsional viscometer

    NSDL National Science Digital Library

    Powell, Adam C., IV

    2003-11-14

    Solve the cylindrical Navier-Stokes equations for polymer flow in a torsional viscometer; calculate polymer viscosity from torque; qualitatively evaluate non-Newtonian nature of flow from a second torque data point.

  8. Testicular torsion

    MedlinePLUS

    Torsion of the testis; Testicular ischemia; Testicular twisting ... Sudden severe pain in one testicle. The pain may occur without a clear reason. Swelling within one side of the scrotum ( scrotal swelling ) Nausea or vomiting Lightheadedness ...

  9. Angular Momentum Evolution of Young Stars: Toward a Synthesis of Observations, Theory, and Modeling

    E-print Network

    Keivan G. Stassun; Donald Terndrup

    2003-03-17

    The aim of this AAS Topical Session was to update the community on the current state of knowledge about the angular momentum evolution of young stars. For newcomers to the subject, the session was intended to provide an introduction and general overview and to highlight emerging issues. For experienced workers in this field, the session provided an opportunity for synthesizing recent developments in observations, theory, and modeling of rotation of young stars and for identifying promising new research directions.

  10. Optical surface measurement using phase retrieval hybrid algorithm based on diffraction angular spectrum theory

    NASA Astrophysics Data System (ADS)

    Feng, Liang; Zeng, Zhi-ge; Wu, Yong-qian

    2013-08-01

    In order to test the high dynamic range error beyond one wavelength after the rough polish process, we design a phase retrieval hybrid algorithm based on diffraction angular spectrum theory. Phase retrieval is a wave front sensing method that uses the intensity distribution to reconstruct the phase distribution of optical field. Phase retrieval is established on the model of diffractive propagation and approach the real intensity distribution gradually. In this paper, we introduce the basic principle and challenges of optical surface measurement using phase retrieval, then discuss the major parts of phase retrieval: diffractive propagation and hybrid algorithm. The angular spectrum theory describes the diffractive propagation in the frequency domain instead of spatial domain, which simplifies the computation greatly. Through the theoretical analysis, the angular spectrum in discrete form is more effective when the high frequency part values less and the diffractive distance isn't far. The phase retrieval hybrid algorithm derives from modified GS algorithm and conjugate gradient method, aiming to solve the problem of phase wrapping caused by the high dynamic range error. In the algorithm, phase distribution is described by Zernike polynomials and the coefficients of Zernike polynomials are optimized by the hybrid algorithm. Simulation results show that the retrieved phase distribution and real phase distribution are quite contiguous for the high dynamic range error beyond ?.

  11. Theory for noise of propellers in angular inflow with parametric studies and experimental verification

    NASA Astrophysics Data System (ADS)

    Hanson, Donald B.; Parzych, David J.

    1993-03-01

    This report presents the derivation of a frequency domain theory and working equations for radiation of propeller harmonic noise in the presence of angular inflow. In applying the acoustic analogy, integration over the tangential coordinate of the source region is performed numerically, permitting the equations to be solved without approximation for any degree of angular inflow. Inflow angle is specified in terms of yaw, pitch, and roll angles of the aircraft. Since these can be arbitrarily large, the analysis applies with equal accuracy to propellers and helicopter rotors. For thickness and loading, the derivation is given in complete detail with working equations for near and far field. However, the quadrupole derivation has been carried only far enough to show feasibility of the numerical approach. Explicit formulas are presented for computation of source elements, evaluation of Green's functions, and location of observer points in various visual and retarded coordinate systems. The resulting computer program, called WOBBLE has been written in FORTRAN and follows the notation of this report very closely. The new theory is explored to establish the effects of varying inflow angle on axial and circumferential directivity. Also, parametric studies were performed to evaluate various phenomena outside the capabilities of earlier theories, such as an unsteady thickness effect. Validity of the theory was established by comparison with test data from conventional propellers and Prop Fans in flight and in wind tunnels under a variety of operating conditions and inflow angles.

  12. Theory for noise of propellers in angular inflow with parametric studies and experimental verification

    NASA Technical Reports Server (NTRS)

    Hanson, Donald B.; Parzych, David J.

    1993-01-01

    This report presents the derivation of a frequency domain theory and working equations for radiation of propeller harmonic noise in the presence of angular inflow. In applying the acoustic analogy, integration over the tangential coordinate of the source region is performed numerically, permitting the equations to be solved without approximation for any degree of angular inflow. Inflow angle is specified in terms of yaw, pitch, and roll angles of the aircraft. Since these can be arbitrarily large, the analysis applies with equal accuracy to propellers and helicopter rotors. For thickness and loading, the derivation is given in complete detail with working equations for near and far field. However, the quadrupole derivation has been carried only far enough to show feasibility of the numerical approach. Explicit formulas are presented for computation of source elements, evaluation of Green's functions, and location of observer points in various visual and retarded coordinate systems. The resulting computer program, called WOBBLE has been written in FORTRAN and follows the notation of this report very closely. The new theory is explored to establish the effects of varying inflow angle on axial and circumferential directivity. Also, parametric studies were performed to evaluate various phenomena outside the capabilities of earlier theories, such as an unsteady thickness effect. Validity of the theory was established by comparison with test data from conventional propellers and Prop Fans in flight and in wind tunnels under a variety of operating conditions and inflow angles.

  13. Torsional stress measurement by axial displacement

    Microsoft Academic Search

    J. J. Deer

    1971-01-01

    An apparatus is described for the measurement of torque by converting angular displacement to axial displacement. A stress-responsive pulley is loosely mounted on a drive shaft by a plain bearing and a short screw-threaded section. The pulley is attached to the shaft by means of a torsion spring. In use a retarding effect upon the pulley causes angular displacement within

  14. The Reidemeister zeta function with applications to Nielsen theory and a connection with Reidemeister torsion

    Microsoft Academic Search

    Alexander Fel'shtyn; Richard Hill

    1994-01-01

    In this paper we study, the Reidemeister zeta function. We prove rationality and functional equations of the Reidemeister zeta function of an endomorphism of finite group. We also obtain these results for eventually commutative endomorphisms. These results are applied to the theory of Reidemeister and Nielsen numbers of self-maps of topological spaces. Our method is to identify the Reidemeister number

  15. Poincaré and de Sitter gauge theories of gravity with propagating torsion

    Microsoft Academic Search

    A. A. Tseytlin

    1982-01-01

    We consider a gauge approach to the gravitational theory based on the local Poincaré P10 or de Sitter S10 groups. The P10 gauge rotations and translations take place in the tangent spaces to the space-time manifold. We interpret the independence of matter fields from the tangent vectors as the necessity to use a nonlinear realization of the P10 or S10

  16. Some Remarks about Duality, Analytic Torsion and Gaussian Integration in Antisymmetric Field Theories

    Microsoft Academic Search

    Alexander Cardona; Blaise Pascal

    2000-01-01

    From a path integral point of view (e.g. \\\\cite{Q98}) physicists have shown\\u000ahow {\\\\it duality} in antisymmetric quantum field theories on a closed\\u000aspace-time manifold $M$ relies in a fundamental way on Fourier Transformations\\u000aof formal infinite-dimensional volume measures. We first review these facts\\u000afrom a measure theoretical point of view, setting the importance of the Hodge\\u000adecomposition theorem in

  17. Torsional Weyl-Dirac Electrodinamics

    E-print Network

    Mark Israelit

    2007-12-26

    Issuing from a geometry with nonmetricity and torsion we build up a classical theory of gravitation and electromagnetism. The theory is coordinate covariant as well Weyl-gauge covariant. Massless and massive photons, intrinsic electr. and magn. currents exist in this framework. The field EQ-s and EQ-s of motion are derived from a geometrically based action. It is shown that the magn.-magn. interaction is transmitted by massive photons. A magn. charge (monopole) cannot be located together with an electr. one. In absence of torsion and in the Einstein gauge one obtains the Einstein-Maxwell theory.

  18. Axions in gravity with torsion

    NASA Astrophysics Data System (ADS)

    Castillo-Felisola, Oscar; Corral, Cristóbal; Kovalenko, Sergey; Schmidt, Iván; Lyubovitskij, Valery E.

    2015-04-01

    We study a scenario allowing a solution of the strong charge parity problem via the Peccei-Quinn mechanism, implemented in gravity with torsion. In this framework there appears a torsion-related pseudoscalar field known as the Kalb-Ramond axion. We compare it with the so-called Barbero-Immirzi axion recently proposed in the literature also in the context of the gravity with torsion. We show that they are equivalent from the viewpoint of the effective theory. The phenomenology of these torsion-descended axions is completely determined by the Planck scale without any additional model parameters. These axions are very light and very weakly interacting with ordinary matter. We briefly comment on their astrophysical and cosmological implications in view of the recent BICEP2 and Planck data.

  19. An experimental study torsional fretting behaviors of LZ50 steel

    Microsoft Academic Search

    Zhen-bing Cai; Min-hao Zhu; Zhong-rong Zhou

    2010-01-01

    Four simple fretting modes are defined according to relative motion: tangential, radial, rotational, and torsional fretting. This paper presents a new test rig that was developed from a low-speed reciprocating rotary system to show torsional fretting wear under ball-on-flat contact. Torsional fretting behavior was investigated for LZ50 steel flats against AISI52100 steel balls under various angular displacement amplitudes and normal

  20. Discrete Torsion Defects

    NASA Astrophysics Data System (ADS)

    Brunner, Ilka; Carqueville, Nils; Plencner, Daniel

    2015-07-01

    Orbifolding two-dimensional quantum field theories by a symmetry group can involve a choice of discrete torsion. We apply the general formalism of `orbifolding defects' to study and elucidate discrete torsion for topological field theories. In the case of Landau-Ginzburg models only the bulk sector had been studied previously, and we re-derive all known results. We also introduce the notion of `projective matrix factorisations', show how they naturally describe boundary and defect sectors, and we further illustrate the efficiency of the defect-based approach by explicitly computing RR charges. Roughly half of our results are not restricted to Landau-Ginzburg models but hold more generally, for any topological field theory. In particular we prove that for a pivotal bicategory, any two objects of its orbifold completion that have the same base are orbifold equivalent. Equivalently, from any orbifold theory (including those based on nonabelian groups) the original unorbifolded theory can be obtained by orbifolding via the `quantum symmetry defect'.

  1. Torsional delayed resonator with velocity feedback

    Microsoft Academic Search

    D. Filipovic; Nejat Olgac

    1998-01-01

    This paper concerns a vibration absorption scheme, which is called the delayed resonator (DR). Torsional vibration cases are considered here for the first time with the new scheme. The angular velocity which is a commonly measurable state for rotating systems, is fed back with a controlled time delay, as opposed to the position and acceleration of the earlier studied translational

  2. Torsional Oscillations of the Earths's Core

    NASA Technical Reports Server (NTRS)

    Hide, Raymond; Boggs, Dale H.; Dickey, Jean O.

    1997-01-01

    Torsional oscillations of the Earth's liquid metallic outer core are investigated by diving the core into twenty imaginary e1qui-volume annuli coaxial with the axis of ratation of the Earth and determining temproal fluctuations in the axial component of angular memonetum of each annulus under the assumption of iso-rotation on cylindrical surfaces.

  3. The explicit representation for the angular flux solution in the simplified P{sub N} (SP{sub N}) theory

    SciTech Connect

    Chao, Y. A. [Apartment 101, Building 2, 788 Hong Xu Road, Shanghai 201103 (China); Yamamoto, A. [Nagoya Univ., Furo-cho, Chikusa-ku, Nagoya, 464-8603 (Japan)

    2012-07-01

    The current SP{sub n} theory formulation, via either the asymptotic method or the variational method, does not provide an explicit and calculable representation for the corresponding angular flux solution. It is therefore not possible to reconstruct from the SP{sub n} solution the corresponding angular flux solution, or to extract from a reference transport solution the corresponding SP{sub n} solution. This makes it impossible to calculate the necessary surface discontinuity factors to force consistency between the SP{sub n} solution and the higher level transport solution. Without discontinuity factors, the superiority of SP{sub n} over diffusion could be significantly degraded in practical applications. In this paper we present a different SP{sub n} formulation that provides the explicit angular flux solution such that the physical picture for the SP{sub n} approximation is transparent and the SP{sub n} discontinuity factors can be calculated. (authors)

  4. Theory of the Influence of Environment on the Angular Distribution of Nuclear Radiation

    Microsoft Academic Search

    Helmut Gabriel

    1969-01-01

    The effect of electronic relaxation processes on the angular correlation and on the angular distribution of radiation from oriented nuclei is investigated. The influence of the environment on the radioactive nuclei is taken into account by reducing the density operator for the total system (nucleus and surroundings mutually interacting) to a density operator for the nucleus alone. Elimination of the

  5. Testicular Torsion (For Parents)

    MedlinePLUS

    ... torsion more likely to happen again in the future. If your son's spermatic cord untwists and the ... to the inside of the scrotum to prevent future torsions. Afterward, your son will be taken to ...

  6. Variable stiffness torsion springs

    NASA Technical Reports Server (NTRS)

    Alhorn, Dean C. (inventor); Polites, Michael E. (inventor)

    1994-01-01

    In a torsion spring the spring action is a result of the relationships between the torque applied in twisting the spring, the angle through which the torsion spring twists, and the modulus of elasticity of the spring material in shear. Torsion springs employed industrially have been strips, rods, or bars, generally termed shafts, capabable of being flexed by twisting their axes. They rely on the variations in shearing forces to furnish an internal restoring torque. In the torsion springs herein the restoring torque is external and therefore independent of the shearing modulus of elasticity of the torsion spring shaft. Also provided herein is a variable stiffness torsion spring. This torsion spring can be so adjusted as to have a given spring constant. Such variable stiffness torsion springs are extremely useful in gimballed payloads such as sensors, telescopes, and electronic devices on such platforms as a space shuttle or a space station.

  7. Variable stiffness torsion springs

    NASA Technical Reports Server (NTRS)

    Alhorn, Dean C. (inventor); Polites, Michael E. (inventor)

    1995-01-01

    In a torsion spring the spring action is a result of the relationships between the torque applied in twisting the spring, the angle through which the torsion spring twists, and the modulus of elasticity of the spring material in shear. Torsion springs employed industrially have been strips, rods, or bars, generally termed shafts, capabable of being flexed by twisting their axes. They rely on the variations in shearing forces to furnish an internal restoring torque. In the torsion springs herein the restoring torque is external and therefore independent of the shearing modulus of elasticity of the torsion spring shaft. Also provided herein is a variable stiffness torsion spring. This torsion spring can be so adjusted as to have a given spring constant. Such variable stiffness torsion springs are extremely useful in gimballed payloads such as sensors, telescopes, and electronic devices on such platforms as a space shuttle or a space station.

  8. Variable stiffness torsion springs

    Microsoft Academic Search

    Dean C. Alhorn; Michael E. Polites

    1995-01-01

    In a torsion spring the spring action is a result of the relationships between the torque applied in twisting the spring, the angle through which the torsion spring twists, and the modulus of elasticity of the spring material in shear. Torsion springs employed industrially have been strips, rods, or bars, generally termed shafts, capabable of being flexed by twisting their

  9. Variable stiffness torsion springs

    Microsoft Academic Search

    Dean C. Alhorn; Michael E. Polites

    1994-01-01

    In a torsion spring the spring action is a result of the relationships between the torque applied in twisting the spring, the angle through which the torsion spring twists, and the modulus of elasticity of the spring material in shear. Torsion springs employed industrially have been strips, rods, or bars, generally termed shafts, capabable of being flexed by twisting their

  10. About Torsional Weyl-Dirac Electrodynamics

    E-print Network

    Mark Israelit

    2007-12-26

    A classical general relativistic theory possessing magnetic currents, as well electric ones and admitting massive photons was built up. As the geometric basis serves a space with Weylian non-metricity and torsion. The theory is coordinate covariant as well Weyl-gauge covariant. In the limit one obtains the ordinary Einstein-Maxwell theory.

  11. Torsional Stability of Aluminum Alloy Seamless Tubing

    NASA Technical Reports Server (NTRS)

    Moore, R L; Paul, D A

    1939-01-01

    Torsion tests were made on 51ST aluminum-alloy seamless tubes having diameter-to-thickness ratios of from 77 to 139 and length-to-diameter ratios of from 1 to 60. The torsional strengths developed in the tubes which failed elastically (all tubes having lengths greater than 2 to 6 times the diameter) were in most cases within 10 percent of the value indicated by the theories of Donnel, Timoshenko, and Sturm, assuming a condition of simply supported ends.

  12. Vaidya-like exact solutions with torsion

    NASA Astrophysics Data System (ADS)

    Blagojevi?, M.; Cvetkovi?, B.

    2015-05-01

    Starting from the Oliva-Tempo-Troncoso black hole, a solution of the Bergshoeff-Hohm-Townsend massive gravity, a class of the Vaidya-like exact vacuum solutions with torsion is constructed in the three-dimensional Poincaré gauge theory. A particular subclass of these solutions is shown to possess the asymptotic conformal symmetry. The related canonical energy contains a contribution stemming from torsion.

  13. Torsion freeness of edge ideals Maximal Cliques of Comparability Graphs Symbolic Rees algebras Sliding depth for trees On the Ideal Theory of graphs

    E-print Network

    Torsion freeness of edge ideals Maximal Cliques of Comparability Graphs Symbolic Rees algebras ideals Maximal Cliques of Comparability Graphs Symbolic Rees algebras Sliding depth for trees The main recent work. #12;Torsion freeness of edge ideals Maximal Cliques of Comparability Graphs Symbolic Rees

  14. Torsion cosmology and the accelerating universe

    SciTech Connect

    Shie, K.-F. [Department of Physics, National Central University, Chungli 320, Taiwan (China); Nester, James M. [Department of Physics, National Central University, Chungli 320, Taiwan (China); Graduate Institute of Astronomy, National Central University, Chungli 320, Taiwan (China); Center for Mathematics and Theoretical Physics, National Central University, Chungli 320, Taiwan (China); Yo, H.-J. [Department of Physics, National Cheng-Kung University, Tainan 701, Taiwan (China)

    2008-07-15

    Investigations of the dynamic modes of the Poincare gauge theory of gravity found only two good propagating torsion modes; they are effectively a scalar and a pseudoscalar. Cosmology affords a natural situation where one might see observational effects of these modes. Here, we consider only the 'scalar torsion' mode. This mode has certain distinctive and interesting qualities. In particular, this type of torsion does not interact directly with any known matter, and it allows a critical nonzero value for the affine scalar curvature. Via numerical evolution of the coupled nonlinear equations we show that this mode can contribute an oscillating aspect to the expansion rate of the Universe. From the examination of specific cases of the parameters and initial conditions we show that for suitable ranges of the parameters the dynamic 'scalar torsion' model can display features similar to those of the presently observed accelerating universe.

  15. Analytic Torsion of Z_2-graded Elliptic Complexes

    E-print Network

    Mathai, Varghese

    2010-01-01

    We define analytic torsion of Z_2-graded elliptic complexes as an element in the graded determinant line of the cohomology of the complex, generalizing most of the variants of Ray-Singer analytic torsion in the literature. It applies to a myriad of new examples, including flat superconnection complexes, twisted analytic and twisted holomorphic torsions, etc. The definition uses pseudo-differential operators and residue traces. We also study properties of analytic torsion for Z_2-graded elliptic complexes, including the behavior under variation of the metric. For compact odd dimensional manifolds, the analytic torsion is independent of the metric, whereas for even dimensional manifolds, a relative version of the analytic torsion is independent of the metric. Finally, the relation to topological field theories is studied.

  16. Effects of high angular momentum on the unimolecular dissociation of CD2CD2OH: theory and comparisons with experiment.

    PubMed

    McKown, Benjamin G; Ceriotti, Michele; Womack, Caroline C; Kamarchik, Eugene; Butler, Laurie J; Bowman, Joel M

    2013-10-24

    This paper explores the dynamics of a highly rotationally and vibrationally excited radical, CD2CD2OH. The radical is produced from the 193 nm photodissociation of 2-bromoethanol-d4, so it is imparted with high angular momentum and high vibrational energy and subsequently dissociates to several product channels. This paper focuses on characterizing its angular momentum and modeling its effect on the product channels, including the HOD + vinyl-d3 product channel resulting from a frustrated dissociation of the radical originally en route to OH + ethene-d4 that instead results in D atom abstraction. Our impulsive model of the initial photodissociation shows that, for some cases, upward of 200 au of angular momentum is imparted, which greatly affects the dynamics of the competing product channels. Using a permutationally invariant potential energy surface and quasiclassical trajectories, we simulated the dissociation dynamics of CD2CD2OH and compared these results to those of Kamarchik et al. (J. Phys. Chem. Lett. 2010, 1, 3058-3065), who studied the dynamics of CH2CH2OH with zero angular momentum. We found that the recoil translational energy distribution for radicals that dissociated to OH + C2D4 matched experiment closely only when high angular momentum of the initial radical was explicitly included in the trajectory calculations. Similarly, the rate constant for dissociation changes when rotational energy was added to the vibrational energy in the initial conditions. Lastly, we applied the sketch-map dimensionality reduction technique to analyze mechanistic information leading to the vinyl + water product channel. Projecting the ab initio intrinsic reaction coordinates onto the lower dimensional space identified with sketch map offers new insight into the dynamics when one looks at the simulated trajectories in the lower dimensional space. Further analysis shows that the transition path resembles a frustrated dissociation of the OH + ethene radical adduct, followed instead by branching to vinyl + water when the leaving OH group encounters a nearby D atom on the ethene moiety. This characterization is in accord with the one made previously. We show that the transition path bifurcation between the two similar channels occurs at carbon-oxygen distances and oxygen-abstracted deuterium distances of 2-2.5 Å controlled by the C-O-D bond angle with large angles preferentially branching to the water plus vinyl product state. The experimental branching ratios were not reproduced by theory, however, due partly to the insufficient quality of the fitted potential surface. We also have evidence of a minor product channel, HD + vinoxy-d3, from our molecular dynamics simulations that allows us to assign the HD signal in prior experimental work. PMID:24124756

  17. Quantum simulations of gauge theories with ultracold atoms: Local gauge invariance from angular-momentum conservation

    NASA Astrophysics Data System (ADS)

    Zohar, Erez; Cirac, J. Ignacio; Reznik, Benni

    2013-08-01

    Quantum simulations of high-energy physics, and especially of gauge theories, is an emerging and exciting direction in quantum simulations. However, simulations of such theories, compared to simulations of condensed matter physics, must satisfy extra restrictions, such as local gauge invariance and relativistic structure. In this paper we discuss these special requirements, and present a method for quantum simulation of lattice gauge theories using ultracold atoms. This method allows us to include local gauge invariance as a fundamental symmetry of the atomic Hamiltonian, arising from natural atomic interactions and conservation laws (and not as a property of a low-energy sector). This allows us to implement elementary gauge invariant interactions for three lattice gauge theories: U(1) (compact QED), ZN and SU(N) (Yang-Mills), which can be used to build quantum simulators in 1+1 dimensions. We also present a loop method, which uses the elementary interactions as building blocks in the effective construction of quantum simulations for d+1 dimensional lattice gauge theories (d>1), but unlike in previous proposals, here gauge invariance and Gauss's law are natural symmetries, which do not have to be imposed as a constraint. We discuss in detail the quantum simulation of 2+1 dimensional compact QED and provide a numerical proof of principle. The simplicity of the already gauge-invariant elementary interactions of this model suggests it may be useful for future experimental realizations.

  18. Accounting for conformational flexibility and torsional anharmonicity in the H + CH{sub 3}CH{sub 2}OH hydrogen abstraction reactions: A multi-path variational transition state theory study

    SciTech Connect

    Meana-Pañeda, Rubén; Fernández-Ramos, Antonio, E-mail: qf.ramos@usc.es [Department of Physical Chemistry and Center for Research in Biological Chemistry and Molecular Materials, University of Santiago de Compostela, 15706 Santiago de Compostela (Spain)] [Department of Physical Chemistry and Center for Research in Biological Chemistry and Molecular Materials, University of Santiago de Compostela, 15706 Santiago de Compostela (Spain)

    2014-05-07

    This work reports a detailed theoretical study of the hydrogen abstraction reactions from ethanol by atomic hydrogen. The calculated thermal rate constants take into account torsional anharmonicity and conformational flexibility, in addition to the variational and tunneling effects. Specifically, the kinetics calculations were performed by using multi-path canonical variational transition state theory with least-action path tunneling corrections, to which we have added the two-dimensional non-separable method to take into account torsional anharmonicity. The multi-path thermal rate constant is expressed as a sum over conformational reaction channels. Each of these channels includes all the transition states that can be reached by internal rotations. The results show that, in the interval of temperatures between 250 and 2500 K, the account for multiple paths leads to higher thermal rate constants with respect to the single path approach, mainly at low and at high temperatures. In addition, torsional anharmonicity enhances the slope of the Arrhenius plot in this range of temperatures. Finally, we show that the incorporation of tunneling into the hydrogen abstraction reactions substantially changes the contribution of each of the transition states to the conformational reaction channel.

  19. Torsion pendulum revisited

    E-print Network

    Massimo Bassan; Fabrizio De Marchi; Lorenzo Marconi; Giuseppe Pucacco; Ruggero Stanga; Massimo Visco

    2013-05-30

    We present an analysis of the motion of a simple torsion pendulum and we describe how, with straightforward extensions to the usual basic dynamical model, we succeed in explaining some unexpected features we found in our data, like the modulation of the torsion mode at a higher frequency and the frequency splitting of the swinging motion. Comparison with observed values yields estimates for the misalignment angles and other parameters of the model.

  20. Torsion pendulum revisited

    E-print Network

    Bassan, Massimo; Marconi, Lorenzo; Pucacco, Giuseppe; Stanga, Ruggero; Visco, Massimo

    2013-01-01

    We present an analysis of the motion of a simple torsion pendulum and we describe how, with straightforward extensions to the usual basic dynamical model, we succeed in explaining some unexpected features we found in our data, like the modulation of the torsion mode at a higher frequency and the frequency splitting of the swinging motion. Comparison with observed values yields estimates for the misalignment angles and other parameters of the model.

  1. Theory of angular-dispersive, imaging hard-x-ray spectrographs

    NASA Astrophysics Data System (ADS)

    Shvyd'ko, Yuri

    2015-05-01

    A spectrograph is an optical instrument that disperses photons of different energies into distinct directions and space locations and that images photon spectra on a position-sensitive detector. Spectrographs consist of collimating, angular dispersive, and focusing optical elements. Bragg reflecting crystals arranged in an asymmetric scattering geometry can be used as the dispersing elements in the hard-x-ray regime. A ray-transfer matrix technique is applied to propagate x-rays through the optical elements. Several optical designs of hard-x-ray spectrographs are proposed and their performance is analyzed. Spectrographs with an energy resolution of 0.1 meV and a spectral window of imaging up to a few tens of meVs are shown to be feasible for inelastic x-ray scattering (IXS) spectroscopy applications. In another example, a spectrograph with a 1-meV spectral resolution and 85-meV spectral window of imaging is considered for Cu K -edge resonant IXS.

  2. J. Phys. Chem. 1983, 87, 2731-2733 2731 Symmetry-Adapted Transition-State Theory: Nonzero Total Angular Momentum

    E-print Network

    Miller, William H.

    Angular Momentum William H. Mlller Department of Chemistry,and Maferials and Molecular Research Division, 1982; In Final Form: February 8, 1983) It is shown how nonzero total angular momentum is incorporated- aldehyde (1.1) which has a planar transition state: i.e., C, symmetry, and for total angular momentum J = 0

  3. ANGULAR MOMENTUM L Angular Momentum

    E-print Network

    ANGULAR MOMENTUM L #12;#12;#12;#12;#12;#12;p-6' Angular Momentum Case: A few particles Example: This example emphasizes the fact that the value of the angular momentum of a system of particles depends just for reference.). v v v 1 2 3 Calculate the vector angular momentum of the three-particle system

  4. A STRUCTURAL ANALYSIS METHOD OF FRAMED STRUCTURES WITH THIN-WALLED OPEN SECTION MEMBERS BASED ON THE BENDING-TORSIONAL THEORY OF BEAMS

    Microsoft Academic Search

    Y. Fujitani; D. Fujii; Chome Higashi-Hiroshima

    In this paper, we present an effective structural analysis method for a space frame composed by thin-walled section beams by using finite element method. The coordinates transformation of the sectional warping displacements are considered in the present method. The effectiveness and verification of this method is shown through a fundamental example with perpendicularly crossed beams suffering the torsion moment by

  5. Torsional Monopoles and Torqued Geometries in Gravity and Condensed Matter

    SciTech Connect

    Randono, Andrew [Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario N2L 2Y5 (Canada); Hughes, Taylor L. [Department of Physics, University of Illinois, 1110 West Green Street, Urbana, Illinois 61801 (United States)

    2011-04-22

    Torsional degrees of freedom play an important role in modern gravity theories as well as in condensed matter systems where they can be modeled by defects in solids. Here we isolate a class of torsion models that support torsion configurations with a localized, conserved charge that adopts integer values. The charge is topological in nature, and the torsional configurations can be thought of as torsional ''monopole'' solutions. We explore some of the properties of these configurations in gravity models with a nonvanishing curvature and discuss the possible existence of such monopoles in condensed matter systems. To conclude, we show how the monopoles can be thought of as a natural generalization of the Cartan spiral staircase.

  6. Quaternionic analytic torsion Kai Kohler

    E-print Network

    Köhler, Kai

    Quaternionic analytic torsion Kai K¨ohler Gregor Weingart April 10, 2001 Abstract We define an (equivariant) quaternionic analytic torsion for anti- selfdual vector bundles on quaternionic K¨ahler manifolds, using ideas by Leung and Yi. We compute this torsion for vector bundles on quaternionic homogeneous

  7. Planar torsion spring

    NASA Technical Reports Server (NTRS)

    Ihrke, Chris A. (Inventor); Parsons, Adam H. (Inventor); Mehling, Joshua S. (Inventor); Griffith, Bryan Kristian (Inventor)

    2012-01-01

    A torsion spring comprises an inner mounting segment. An outer mounting segment is located concentrically around the inner mounting segment. A plurality of splines extends from the inner mounting segment to the outer mounting segment. At least a portion of each spline extends generally annularly around the inner mounting segment.

  8. CUTS IN THE CCMPLEX ANGULAR MOMENTUM PLANE CUTS IN THE COMPLEX ANGULAR MOMENTUM PLANE

    E-print Network

    Boyer, Edmond

    CUTS IN THE CCMPLEX ANGULAR MOMENTUM PLANE CUTS IN THE COMPLEX ANGULAR MOMENTUM PLANE I.G. HALLIDAY is projected into angular momentum states where the left and right pairs have angular momentum and helicities Imperial College I have been asked to review the recent advances in the theory of cuts in the angular

  9. Primordial magnetic fields and dynamos from parity violated torsion

    NASA Astrophysics Data System (ADS)

    Garcia de Andrade, L. C.

    2012-05-01

    It is well known that torsion induced magnetic fields may seed galactic dynamos, but the price one pays for that is the conformal and gauge invariance breaks and a tiny photon mass. More recently I have shown [L.C. Garcia de Andrade, Phys. Lett. B 468 (2011) 28] that magnetic fields decay in a gauge invariant non-minimal coupling theory of torsion is slow down, which would allow for dynamo action to take place. In this Letter, by adding a parity violation term of the type R? to the non-coupling term, a magnetic dynamo equation is obtained. From dynamo equation it is shown that torsion terms only appear in the dynamo equation when diffusion in the cosmic plasma is present. Torsion breaks the homogeneity of the magnetic field in the universe. Since Zeldovich anti-dynamo theorem assumes that the spacetime should be totally flat, torsion is responsible for violation of anti-dynamo theorem in 2D spatial dimensions. Contrary to previous results torsion induced primordial magnetic fields cannot seed galactic dynamos since from torsion and diffusion coefficient the decaying time of the magnetic field is 106yrs, which is much shorter than the galaxy age.

  10. Torsional Ratcheting Actuating System

    SciTech Connect

    BARNES,STEPHEN MATTHEW; MILLER,SAMUEL L.; RODGERS,M. STEVEN; BITSIE,FERNANDO

    2000-01-24

    A new type of surface micromachined ratcheting actuation system has been developed at the Microelectronics Development Laboratory at Sandia National Laboratories. The actuator uses a torsional electrostatic comb drive that is coupled to an external ring gear through a ratcheting scheme. The actuator can be operated with a single square wave, has minimal rubbing surfaces, maximizes comb finger density, and can be used for open-loop position control. The prototypes function as intended with a minimum demonstrated operating voltage of 18V. The equations of motion are developed for the torsional electrostatic comb drive. The resonant frequency, voltage vs. displacement and force delivery characteristics are predicted and compared with the fabricated device's performance.

  11. Orientifolds with discrete torsion

    E-print Network

    Mathias Klein; Raul Rabadan

    2000-05-25

    We show how discrete torsion can be implemented in D=4, N=1 type IIB orientifolds. Some consistency conditions are found from the closed string and open string spectrum and from tadpole cancellation. Only real values of the discrete torsion parameter are allowed, i.e. epsilon=+-1. Orientifold models are related to real projective representations. In a similar way as complex projective representations are classified by H^2(Gamma,C^*)=H^2(Gamma,U(1)), real projective representations are characterized by H^2(Gamma,R^*)=H^2(Gamma,Z_2). Four different types of orientifold constructions are possible. We classify these models and give the spectrum and the tadpole cancellation conditions explicitly.

  12. Torsion as a dynamic degree of freedom of quantum gravity

    E-print Network

    Sang-Woo Kim; D. G. Pak

    2008-03-05

    The gauge approach to gravity based on the local Lorentz group with a general independent affine connection A_{\\mu cd} is developed. We consider SO(1,3) gauge theory with a Lagrangian quadratic in curvature as a simple model of quantum gravity. The torsion is proposed to represent a dynamic degree of freedom of quantum gravity at scales above the Planckian energy. The Einstein-Hilbert theory is induced as an effective theory due to quantum corrections of torsion via generating a stable gravito-magnetic condensate. We conjecture that torsion possesses an intrinsic quantum nature and can be confined. A minimal Abelian projection for the Lorentz gauge model has been constructed, and an effective theory of the cosmic knot at the Planckian scale is proposed.

  13. Torsional surface waves in a gradient-elastic half-space

    Microsoft Academic Search

    H. G. Georgiadis; I. Vardoulakis; G. Lykotrafitis

    2000-01-01

    The present work deals with torsional wave propagation in a linear gradient-elastic half-space. More specifically, we prove that torsional surface waves (i.e. waves with amplitudes exponentially decaying with distance from the free surface) do exist in a homogeneous gradient-elastic half-space. This finding is in contrast with the well-known result of the classical theory of linear elasticity that torsional surface waves

  14. Beyond the chemiosmotic theory: analysis of key fundamental aspects of energy coupling in oxidative phosphorylation in the light of a torsional mechanism of energy transduction and ATP synthesis--invited review part 1.

    PubMed

    Nath, Sunil

    2010-08-01

    In Part 1 of this invited article, we consider the fundamental aspects of energy coupling in oxidative phosphorylation. The central concepts of the chemiosmotic theory are re-examined and the major problems with its experimental verification are analyzed and reassessed from first principles. Several of its assumptions and interpretations (with regard, for instance, to consideration of the membrane as an inert barrier, the occurrence of energy transduction at thermodynamic equilibrium, the completely delocalized nature of the protonmotive force, and the notion of indirect coupling) are shown to be questionable. Important biological implications of this analysis for molecular mechanisms of biological energy transduction are enumerated. A fresh molecular mechanism of the uncoupling of oxidative phosphorylation by classical weak acid anion uncouplers and an adequate explanation for the existence of uncoupler-resistant mutants (which until now has remained a mystery) has been proposed based on novel insights arising from a new torsional mechanism of energy transduction and ATP synthesis. PMID:20490637

  15. Angular and Linear Velocity Estimation for a Re-Entry Vehicle Using Six Distributed Accelerometers: Theory, Simulation and Feasibility

    SciTech Connect

    Clark, G

    2003-04-28

    This report describes a feasibility study. We are interested in calculating the angular and linear velocities of a re-entry vehicle using six acceleration signals from a distributed accelerometer inertial measurement unit (DAIMU). Earlier work showed that angular and linear velocity calculation using classic nonlinear ordinary differential equation (ODE) solvers is not practically feasible, due to mathematical and numerical difficulties. This report demonstrates the theoretical feasibility of using model-based nonlinear state estimation techniques to obtain the angular and linear velocities in this problem. Practical numerical and calibration issues require additional work to resolve. We show that the six accelerometers in the DAIMU are not sufficient to provide observability, so additional measurements of the system states are required (e.g. from a Global Positioning System (GPS) unit). Given the constraint that our system cannot use GPS, we propose using the existing on-board 3-axis magnetometer to measure angular velocity. We further show that the six nonlinear ODE's for the vehicle kinematics can be decoupled into three ODE's in the angular velocity and three ODE's in the linear velocity. This allows us to formulate a three-state Gauss-Markov system model for the angular velocities, using the magnetometer signals in the measurement model. This re-formulated model is observable, allowing us to build an Extended Kalman Filter (EKF) for estimating the angular velocities. Given the angular velocity estimates from the EKF, the three ODE's for the linear velocity become algebraic, and the linear velocity can be calculated by numerical integration. Thus, we do not need direct measurements of the linear velocity to provide observability, and the technique is mathematically feasible. Using a simulation example, we show that the estimator adds value over the numerical ODE solver in the presence of measurement noise. Calculating the velocities in the presence of significant measurement noise is not feasible with a classic ODE solver. The EKF is able to deal effectively with the noise and provide useful angular velocity estimates. The linear velocity estimates for this simulation show numerical difficulties associated with the nonlinear ODE's and the quadrature operation. Future work will focus on dealing with practical numerical issues and the issue of calibrating the DAIMU to deal with uncertainties in the accelerometer positions and locations.

  16. Quaternionic analytic torsion Kai K"ohler

    E-print Network

    Köhler, Kai

    Quaternionic analytic torsion Kai K We define an (equivariant) quaternionic analytic torsion for anti- selfdual vector bundles on quaternionic K"ahler manifolds, using ideas by Leung and Yi. We compute this torsion for vector bundles

  17. Theoretical-experimental correlation for buckling of composite cylinders under combined compression and torsion

    NASA Technical Reports Server (NTRS)

    Herakovich, C. T.

    1978-01-01

    Comparison between theory and experiment for buckling of laminated graphite-epoxy and boron-epoxy cylinders under combined compression and torsion are presented. The experimental results are compared to a theory by Wu. It is shown that there is excellent agreement between theory and experiment for pure torsional loading (positive and negative), experimental buckling loads for pure compression are well below the predicted values, and good correlation is exhibited between theory and experiment for buckling under combined loading when compared in the form of normalized buckling interaction diagrams in axial-torsional load space.

  18. Torsional Electromechanics of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Joselevich, Ernesto; Cohen-Karni, Tzahi; Segev, Lior; Srur-Lavi, Onit; Cohen, Sidney R.

    2007-03-01

    Carbon nanotubes are known to be distinctly metallic or semiconducting depending on their diameter and chirality. Here we show that continuously varying the chirality by mechanical torsion can induce conductance oscillations, which can be attributed to metal-semiconductor periodic transitions. The phenomenon is observed in multi-walled carbon nanotubes, where both the torque and the current are shown to be carried predominantly by the outermost wall. The oscillation period with torsion is consistent with the theoretical shifting of the corners of the first Brillouin zone of graphene across different subbands allowed in the nanotube. Beyond a critical torsion, the conductance irreversibly drops due to torsional failure, allowing us to determine the torsional strength of carbon nanotubes. Our experiments indicate that carbon nanotubes could be used as self-sensing torsional springs for nanoelectromechanical systems (NEMS). [1] E. Joselevich, Twisting nanotubes: From torsion to chirality, ChemPhysChem 2006, 7, 1405. [2] T. Cohen-Karni, L. Segev, O. Srur-Lavi, S. R. Cohen, E. Joselevich, Torsional electromechanical quantum oscillations in carbon nanotubes, Nature Nanotechnology, 2006, 1, 36.

  19. Orbital angular momentum in phase space

    E-print Network

    I. Rigas; L. L. Sanchez-Soto; A. B. Klimov; J. Rehacek; Z. Hradil

    2010-11-29

    A comprehensive theory of the Weyl-Wigner formalism for the canonical pair angle-angular momentum is presented. Special attention is paid to the problems linked to rotational periodicity and angular-momentum discreteness.

  20. Angular integrals in d dimensions

    NASA Astrophysics Data System (ADS)

    Somogyi, Gábor

    2011-08-01

    We discuss the evaluation of certain d-dimensional angular integrals which arise in perturbative field theory calculations. We find that the angular integral with n denominators can be computed in terms of a certain special function, the so-called H-function of several variables. We also present several illustrative examples of the general result and briefly consider some applications.

  1. Solar System Experiments and the Interpretation of Saa's Model of Gravity with Propagating Torsion as a Theory with Variable Plank "Constant"

    E-print Network

    P. Fiziev; S. Yazadjiev

    1998-07-19

    It is shown that the recently proposed interpretation of the transposed equi-affine theory of gravity as a theory with variable Plank "constant" is inconsistent with basic solar system gravitational experiments.

  2. Torsion as a source of expansion in a Bianchi type-I universe in the self-consistent Einstein-Cartan theory of a perfect fluid with spin density

    NASA Technical Reports Server (NTRS)

    Bradas, James C.; Fennelly, Alphonsus J.; Smalley, Larry L.

    1987-01-01

    It is shown that a generalized (or 'power law') inflationary phase arises naturally and inevitably in a simple (Bianchi type-I) anisotropic cosmological model in the self-consistent Einstein-Cartan gravitation theory with the improved stress-energy-momentum tensor with the spin density of Ray and Smalley (1982, 1983). This is made explicit by an analytical solution of the field equations of motion of the fluid variables. The inflation is caused by the angular kinetic energy density due to spin. The model further elucidates the relationship between fluid vorticity, the angular velocity of the inertially dragged tetrads, and the precession of the principal axes of the shear ellipsoid. Shear is not effective in damping the inflation.

  3. Torsional resonances in magnetoelastic bimorphs

    SciTech Connect

    Peuzin, J.C.; Mackay, K. [Laboratoire de Magnetisme Louis Neel, CNRS, BP166, 38042 Grenoble Cedex 9 (France)] [Laboratoire de Magnetisme Louis Neel, CNRS, BP166, 38042 Grenoble Cedex 9 (France)

    1997-02-01

    In this paper, we show that torsional as well as flexion modes can be excited rather naturally in a magnetoelastic bimorph. This behavior is in contrast with that of usual piezoelectric bimorphs in which only flexion modes can be excited. We describe experimental results on the torsional resonances of bimorphs composed of a glass substrate and a highly magnetostrictive thin film of (TbDy)(FeCo){sub 2} and show how basic linear piezomagnetic constants may be extracted from the resonance data. Finally, we discuss some possible applications of torsional resonance in magnetoelastic bimorphs. {copyright} {ital 1997 American Institute of Physics.}

  4. Optical fiber accelerometer based on MEMS torsional micromirror

    NASA Astrophysics Data System (ADS)

    Zeng, Fanlin; Zhong, Shaolong; Xu, Jing; Wu, Yaming

    2008-03-01

    A novel structure of optical fiber accelerometer based on MEMS torsional micro-mirror is introduced, including MEMS torsional micro-mirror and optical signal detection. The micro-mirror is a non-symmetric one, which means that the torsional bar supporting the micro-mirror is not located in the axis where the center of the micro-mirror locates. The optical signal detection is composed of PIN diode and dual fiber collimator, which is very sensitive to the coupling angle between the input fiber and output fiber. The detection principle is that acceleration is first transformed into torsional angle of the micro-mirror, then, optical insertion loss of the dual fiber collimator caused by the angle can be received by PIN. So under the flow of acceleration to torsional angle to optical signal attenuation to optical power detection, the acceleration is detected. The theory about sensing and optical signal detect of the device are discussed in this paper. The sensitive structure parameters and performance parameters are calculated by MATLAB. To simulate the static and modal analysis, the finite element analysis, ANSYS, is employed. Based on the above calculation, several optimization methods and the final structure parameters are given. The micro-mirror is completed by using silicon-glass bonding and deep reactive ion etching (DRIE). In the experiment, the acceleration is simulated by electrostatic force and the test results show that the static acceleration detection agrees with the theory analysis very well.

  5. Torsion Stiffness of a Protein Pair Determined by Magnetic Particles

    PubMed Central

    Janssen, X.J.A.; van Noorloos, J.M.; Jacob, A.; van IJzendoorn, L.J.; de Jong, A.M.; Prins, M.W.J.

    2011-01-01

    We demonstrate the ability to measure torsion stiffness of a protein complex by applying a controlled torque on a magnetic particle. As a model system we use protein G bound to an IgG antibody. The protein pair is held between a magnetic particle and a polystyrene substrate. The angular orientation of the magnetic particle shows an oscillating behavior upon application of a rotating magnetic field. The amplitude of the oscillation increases with a decreasing surface coverage of antibodies on the substrate and with an increasing magnitude of the applied field. For decreasing antibody coverage, the torsion spring constant converges to a minimum value of 1.5 × 103 pN·nm/rad that corresponds to a torsion modulus of 4.5 × 104 pN·nm2. This torsion stiffness is an upper limit for the molecular bond between the particle and the surface that is tentatively assigned to a single protein G–IgG protein pair. This assignment is supported by interpreting the measured stiffness with a simple mechanical model that predicts a two orders of magnitude larger stiffness for the protein G–IgG complex than values found for micrometer length dsDNA. This we understand from the structural properties of the molecules, i.e., DNA is a long and flexible chain-like molecule, whereas the antibody-antigen couple is orders of magnitude smaller and more globular in shape due to the folding of the molecules. PMID:21539795

  6. Testicular torsion repair - series (image)

    MedlinePLUS

    The testicles are suspended in the scrotal sac. ... Testicular torsion occurs when the testicle, normally attached to the scrotum by a small ligament at its base, becomes loose. The testicle can then twist on itself, ...

  7. Twisted ultrathin silicon nanowires: A possible torsion electromechanical nanodevice

    NASA Astrophysics Data System (ADS)

    Garcia, J. C.; Justo, J. F.

    2014-11-01

    Nanowires have been considered for a number of applications in nanometrology. In such a context, we have explored the possibility of using ultrathin twisted nanowires as torsion nanobalances to probe forces and torques at molecular level with high precision, a nanoscale system analogous to the Coulomb's torsion balance electrometer. In order to achieve this goal, we performed a first-principles investigation on the structural and electronic properties of twisted silicon nanowires, in their pristine and hydrogenated forms. The results indicated that wires with pentagonal and hexagonal cross-sections are the thinnest stable silicon nanostructures. Additionally, all wires followed a Hooke's law behavior for small twisting deformations. Hydrogenation leads to spontaneous twisting, but with angular spring constants considerably smaller than the ones for the respective pristine forms. We observed considerable changes on the nanowire electronic properties upon twisting, which allows to envision the possibility of correlating the torsional angular deformation with the nanowire electronic transport. This could ultimately allow a direct access to measurements on interatomic forces at molecular level.

  8. Plastic Behavior and Fracture of Aluminum and Copper in Torsion Tests

    SciTech Connect

    Bressan, Jose Divo [Department of Mechanical Engineering - UDESC Joinville - 89.223-100 Joinville - SC (Brazil)

    2007-04-07

    Present work investigates the plastic behavior, work hardening and the beginning of plastic instabilities, of cylindrical specimens deformed by high speed cold plastic torsion tests and at low speed tensile test. The tests were carried out in a laboratory torsion test equipment and an universal tensile test machine. The tensile tests were performed at room temperature in an universal testing machine at low strain rate of 0.034/s. Experimental torsion tests were carried out at constant angular speed that imposed a constant shear strain rate to the specimen. In the tests, the rotation speed were set to 62 rpm and 200 rpm which imposed high strain rates of about 2/s and 6.5/s respectively. The torsion tests performed at room temperature on annealed commercial pure copper and aluminum. Two types of torsion specimen for aluminum were used: solid and tubular. The solid aluminum specimen curves presented various points of maximum torque. The tubular copper specimens showed two points of maximum. Shear bands or shear strain localization at specimen were possibly the mechanism of maximum torque points formation. The work hardening coefficient n and the strain rate sensitivity parameter m were evaluated from the equivalent stress versus strain curve from tensile and torsion tests. The n-value remained constant whereas the m-value increased ten folds for aluminum specimens: from tensile test m= 0.027 and torsion test m= 0.27. However, the hardening curves were sigmoidal.

  9. INVARIANTS, TORSION INDICES AND ORIENTED COHOMOLOGY OF COMPLETE FLAGS

    E-print Network

    group rings 4 3. Differential operators and C 7 4. Endomorphisms of a formal group ring 10 5. Torsion of such a theory is the Chow group CH of algebraic cycles modulo rational equivalence. Let G be a split semi-simple Discovery Grant. 1 #12;2 B. CALM`ES, V. PETROV, AND K. ZAINOULLINE Demazure studied the cohomology ring H

  10. INVARIANTS, TORSION INDICES AND ORIENTED COHOMOLOGY OF COMPLETE FLAGS

    E-print Network

    Calmès, Baptiste

    group rings 4 3. Differential operators and C 7 4. Endomorphisms of a formal group ring 10 5. Torsion of such a theory is the Chow group CH of algebraic cycles modulo rational equivalence. Let G be a split semi-simple. ZAINOULLINE Demazure studied the cohomology ring H(G/B; Z) and provided an algorithm to compute H(G/B; Z

  11. Origin of solar torsional oscillations

    E-print Network

    Matthias Rempel

    2006-10-07

    Helioseismology has revealed many details of solar differential rotation and also its time variation, known as torsional oscillations. So far there is no generally accepted theoretical explanation for torsional oscillations, even though a close relation to the solar activity cycle is evident. On the theoretical side non-kinematic dynamo models (including the Lorentz force feedback on differential rotation) have been used to explain torsional oscillations. In this paper we use a slightly different approach by forcing torsional oscillations in a mean field differential rotation model. Our aim is not a fully self-consistent model but rather to point out a few general properties of torsional oscillations and their possible origin that are independent from a particular dynamo model. We find that the poleward propagating high latitude branch of the torsional oscillations can be explained as a response of the coupled differential rotation / meridional flow system to periodic forcing in mid-latitudes, of either mechanical (Lorentz force) or thermal nature. The speed of the poleward propagation sets constraints on the value of the turbulent viscosity in the solar convection zone to be less than 3x10^8 m^2/s. We also show that the equatorward propagating low latitude branch is very unlikely a consequence of mechanical forcing (Lorentz force) alone, but rather of thermal origin due to the Taylor-Proudman theorem.

  12. Holography in 3D AdS gravity with torsion

    E-print Network

    Milutin Blagojevi?; Branislav Cvetkovi?; Olivera Miskovic; Rodrigo Olea

    2013-05-06

    Basic aspects of the AdS/CFT correspondence are studied in the framework of 3-dimensional gravity with torsion. After choosing a consistent holographic ansatz, we formulate an improved approach to the Noether--Ward identities for the boundary theory. The method is applied first to the topological Mielke--Baekler model, and then to the more interesting (parity-preserving) 3-dimensional gravity with propagating torsion. In both cases, we find the finite holographic energy-momentum and spin currents and obtain the associated (anomalous) Noether--Ward identities.

  13. Transverse angular momentum of photons

    E-print Network

    Andrea Aiello; Christoph Marquardt; Gerd Leuchs

    2010-03-04

    We develop the quantum theory of transverse angular momentum of light beams. The theory applies to paraxial and quasi-paraxial photon beams in vacuum, and reproduces the known results for classical beams when applied to coherent states of the field. Both the Poynting vector, alias the linear momentum, and the angular momentum quantum operators of a light beam are calculated including contributions from first-order transverse derivatives. This permits a correct description of the energy flow in the beam and the natural emergence of both the spin and the angular momentum of the photons. We show that for collimated beams of light, orbital angular momentum operators do not satisfy the standard commutation rules. Finally, we discuss the application of our theory to some concrete cases.

  14. Transverse angular momentum of photons

    SciTech Connect

    Aiello, Andrea [Max Planck Institute for the Science of Light, Guenter-Scharowsky-Strasse 1/Bau 24, D-91058 Erlangen (Germany); Marquardt, Christoph; Leuchs, Gerd [Max Planck Institute for the Science of Light, Guenter-Scharowsky-Strasse 1/Bau 24, D-91058 Erlangen (Germany); Institute for Optics, Information and Photonics, University Erlangen-Nuernberg, Staudtstrasse 7/B2, D-91058 Erlangen (Germany)

    2010-05-15

    We develop the quantum theory of transverse angular momentum of light beams. The theory applies to paraxial and quasiparaxial photon beams in vacuum and reproduces the known results for classical beams when applied to coherent states of the field. Both the Poynting vector, alias the linear momentum, and the angular-momentum quantum operators of a light beam are calculated including contributions from first-order transverse derivatives. This permits a correct description of the energy flow in the beam and the natural emergence of both the spin and the angular momentum of the photons. We show that for collimated beams of light, orbital angular-momentum operators do not satisfy the standard commutation rules. Finally, we discuss the application of our theory to some concrete cases.

  15. Spectral broadening and diffusion by torsional motion in biphenyl.

    PubMed

    Beenken, Wichard J D; Lischka, Hans

    2005-10-01

    We have studied biphenyl by time-dependent density-functional theory. In particular, we have analyzed the dependence of singlet excitation energies and transition dipoles on the torsional angle between the phenyl groups. The torsional spectrum has been computed quantum mechanically as well as semiclassically in order to understand how this influences the broadening of absorption and luminescence spectra. Our results are in best agreement with supersonic jet spectroscopy data, but also fit astonishingly well to spectra of biphenyl in condensed phase. Furthermore, we compare the torsional and vibrational relaxation and discuss qualitatively the general consequences for poly-para-phenylenes and related conjugated polymers as poly-thiophenes, considering, in particular, how side chains and solvents may affect the optical spectra. PMID:16238395

  16. Blade root torsional dampers to reduce hub loads

    NASA Technical Reports Server (NTRS)

    Kottapalli, Sesi

    1992-01-01

    A new method of reducing helicopter rotor hub loads and marginally improving rotor performance by the introduction of large values of blade root torsional damping is presented. Basic theoretical considerations imply that these benefits in hub loads can come about by changes to the blade elastic torsional deflection. This basic theory was analytically verified by using a fully coupled aeroelastic rotorcraft analysis as applied to a modern, articulated rotor blade, namely that of the Sikorsky S-76. From an implementation standpoint, a rotor-based torsional damping device may be more practical than one that involves a major portion of the blade span. Also, a root-based device may allow for the retrofitting of existing helicopter rotor blade/hub configurations.

  17. Angular Measure

    NSDL National Science Digital Library

    Students will learn about the Transit of Venus through reading a NASA press release and viewing a NASA eClips video that describes several ways to observe transits. Then students will study angular measurement by learning about parallax and how astronomers use this geometric effect to determine the distance to Venus during a Transit of Venus. This activity is part of the Space Math multimedia modules that integrate NASA press releases, NASA archival video, and mathematics problems targeted at specific math standards commonly encountered in middle school textbooks. The modules cover specific math topics at multiple levels of difficulty with real-world data and use the 5E instructional sequence.

  18. Temperature-independent FBG-type torsion sensor based on combinatorial torsion beam

    Microsoft Academic Search

    Weigang Zhang; Guiyun Kai; Xiaoyi Dong; Shuzhong Yuan; Qida Zhao

    2002-01-01

    A new method of temperature-independent torsion measurement based on a combinatorial torsion beam is proposed and demonstrated. One half of the unique sensing fiber Bragg grating (FBG) is linked to a solid torsion beam, while the other is fixed to a less rigid part of the air-hole torsion beam. The spectral response of the FBG is split into two spectral

  19. Torsional waves operating in geodynamo and magnetoconvection simulations

    NASA Astrophysics Data System (ADS)

    Teed, Robert; Jones, Chris; Tobias, Steve

    2015-04-01

    Torsional waves are a principal feature of the dynamics of the fluid outer core where the Earth's magnetic field is generated. These oscillations are Alfvén waves operating about an equilibrium known as a Taylor state (Taylor, 1963) and they propagate in the cylindrical radial direction. The change in core angular momentum inferred from geomagnetic observations has a measurable impact on the length of the day, and the small decadal variations in the length-of-day signal confirm the existence of torsional oscillations (Holme & de Viron, 2013). Many questions remain unanswered about the exact nature of these waves and this presentation will attempt to address some of these. In order to gain insight we perform three-dimensional spherical dynamo and magnetoconvection simulations in parameter regimes where Earth-like magnetic fields are produced. Many of our simulations produce the desired torsional oscillations, identified by their movement at the correct Alfvén speed, and several show Earth-like core travel times of around 4 years. Our dynamo simulations (Teed et al., 2014) show torsional waves within the tangent cylinder region that also have the ability to pass through this theoretical cylinder. By calculating the driving terms for these waves we find that both the Reynolds force and ageostrophic convection acting through the Lorentz force can be important in driving torsional oscillations. Driven by a desire to reach smaller Ekman numbers and larger magnetic field strengths, which are computationally unattainable in dynamo simulations, we perform, in our follow up work, magnetoconvection simulations (Teed et al., 2015) by imposing a dipolar field on the core-mantle boundary. Under this configuration we find a transition, at low Ekman numbers, to regimes where excitation is found only at the tangent cylinder, is delivered by the Lorentz force and gives rise to a periodic Earth-like wave pattern. This pattern is approximately operating on a 4 to 5 year timescale, similar to the 6 year period expected of the waves in the Earth. References Holme, R. & de Viron, O., 2013. Characterization and implications of intradecadal variations in length of day. Nature 499 (7457), 202-204. Taylor, J., 1963. The magneto-hydrodynamics of a rotating fluid and the Earth's dynamo problem. Proc. Roy. Soc. A 274, 274-283. Teed, R., Jones, C., Tobias, S., 2014. The dynamics and excitation of torsional waves in geodynamo simulations. Geophys. J. Int. 196 (2), 724-735. Teed, R., Jones, C., Tobias, S., 2015. The transition to Earth-like torsional oscillations in magnetoconvection simulations. Submitted

  20. Torsional Carbon Nanotube Artificial Muscles

    NASA Astrophysics Data System (ADS)

    Foroughi, Javad; Spinks, Geoffrey M.; Wallace, Gordon G.; Oh, Jiyoung; Kozlov, Mikhail E.; Fang, Shaoli; Mirfakhrai, Tissaphern; Madden, John D. W.; Shin, Min Kyoon; Kim, Seon Jeong; Baughman, Ray H.

    2011-10-01

    Rotary motors of conventional design can be rather complex and are therefore difficult to miniaturize; previous carbon nanotube artificial muscles provide contraction and bending, but not rotation. We show that an electrolyte-filled twist-spun carbon nanotube yarn, much thinner than a human hair, functions as a torsional artificial muscle in a simple three-electrode electrochemical system, providing a reversible 15,000° rotation and 590 revolutions per minute. A hydrostatic actuation mechanism, as seen in muscular hydrostats in nature, explains the simultaneous occurrence of lengthwise contraction and torsional rotation during the yarn volume increase caused by electrochemical double-layer charge injection. The use of a torsional yarn muscle as a mixer for a fluidic chip is demonstrated.

  1. [Torsion of the gallbladder (author's transl)].

    PubMed

    Alawneh, I

    1976-12-01

    The torsion of the gallbladder is a rare disease. A case of torsion of the gallbladder is reported who came to surgery under the diagnosis of acute appendicitis in an elder person. Factors facilitating torsion of the gallbladder are discussed. The only form of therapy is immediate cholecystectomy. PMID:1018578

  2. Magnetogenesis from axion and dilaton electromagnetism in torsioned spacetime

    E-print Network

    L. C. G. Andrade

    2015-01-09

    Recently much controversy has been shed on BICEP 2 experiments for the concerning this validity or not and a possible set of new experiments to detect primordial inflation and gravitational waves. Since gravitational waves imply the existence of primordial magnetic fields in this context, C Bonvin, R Durrer and R Marteens [Phys Rev Lett (2014)] have tried to associate the presence of primordial magnetic fields to BICEP 2 by making use of CMB tensor modes. Here we show that by considering torsion dilatonic lagrangean one obtains cosmological magnetic fields of the order of $B\\sim{10^{-10}G}$ which may seed galactic dynamos. Actually this new result came out of a mistake of a recent paper published by myself in JCAP (2014). These results are more in accordance with Bamba results [JCAP (2014)] in the context of teleparallel theory of gravity with Einstein's distant parallelism and torsion. These results also support Einstein-Cartan sort of theories of gravity from well-known recent data. Another example which supports the use of modified gravities with torsion to investigate magnetogenesis is the alternative exampleof using axions with transmutation into torsion to obtain cosmic magnetic seed bound of $10^{-12}G$.This coincides with the lower bound obtained by Barrow et al [Phys Rev D (2012)] in the interval of $10^{-20}G$ to $10^{-12}G$ in Friedmann universes.

  3. Scalar torsion and a new symmetry of general relativity

    NASA Astrophysics Data System (ADS)

    Fonseca-Neto, J. B.; Romero, C.; Martinez, S. P. G.

    2013-08-01

    We reformulate the general theory of relativity in the language of Riemann-Cartan geometry. We start from the assumption that the space-time can be described as a non-Riemannian manifold, which, in addition to the metric field, is endowed with torsion. In this new framework, the gravitational field is represented not only by the metric, but also by the torsion, which is completely determined by a geometric scalar field. We show that in this formulation general relativity has a new kind of invariance, whose invariance group consists of a set of conformal and gauge transformations, called Cartan transformations. These involve both the metric tensor and the torsion vector field, and are similar to the well known Weyl gauge transformations. By making use of the concept of Cartan gauges, we show that, under Cartan transformations, the new formalism leads to different pictures of the same gravitational phenomena. We illustrate this fact by looking at the one of the classical tests of general relativity theory, namely the gravitational spectral shift. Finally, we extend the concept of space-time symmetry to Riemann-Cartan space-times with scalar torsion and obtain the conservation laws for auto-parallel motions in a static spherically symmetric vacuum space-time in a Cartan gauge, whose orbits are identical to Schwarzschild orbits in general relativity.

  4. An Experimental and Theoretical Study of a Coupling Mechanism Between Longitudinal and Torsional Drillstring Vibrations at the Bit

    Microsoft Academic Search

    Thor Aarrestad; Age Kyllingstad

    1988-01-01

    A mechanism that couples longitudinal and torsional drillstring vibrations at the bit was studied. Torsional vibrations are associated with dynamic variations of the rotational bit speed. When a roller bit runs over a multilobed pattern, these speed variations have been shown to affect the input of longitudinal vibrations. The theory for this coupling mechanisms is verified experimentally by high-rate data

  5. Torsional Electromechanics of Carbon Nanotubes

    Microsoft Academic Search

    Ernesto Joselevich; Tzahi Cohen-Karni; Lior Segev; Onit Srur-Lavi; Sidney R. Cohen

    2007-01-01

    Carbon nanotubes are known to be distinctly metallic or semiconducting depending on their diameter and chirality. Here we show that continuously varying the chirality by mechanical torsion can induce conductance oscillations, which can be attributed to metal-semiconductor periodic transitions. The phenomenon is observed in multi-walled carbon nanotubes, where both the torque and the current are shown to be carried predominantly

  6. Torsion of the fallopian tube

    Microsoft Academic Search

    Peter C Ferrera; Lawrence E Kass; Vincent P Verdile

    1995-01-01

    Isolated fallopian tube torsion is a rare entity that most frequently occurs during the menstruating years, but has also been reported in premenopausal and postmenopausal women. Diagnosis of this condition is often delayed because of the rarity of its occurrence and prolonged investigations to rule out more common causes of acute abdominal pain. A case of a 13-year-old girl with

  7. Simultaneous normal and torsional force measurement by cantilever surface contour analysis

    NASA Astrophysics Data System (ADS)

    Kumanchik, Lee; Schmitz, Tony; Pratt, Jon

    2011-05-01

    This study presents an alternative to the current Hooke's law-based force relation between rectangular cantilever deflection and applied force. In the new approach, a transduction constant is presented that (1) includes no cross-talk between torsion and normal force components, (2) is independent of the load application point, and (3) does not depend on the cantilever beam length. Rather than measuring the cantilever deformation at a single point (such as the tip location), it is measured at multiple adjacent points using scanning white light interferometry to provide a three-dimensional description of the cantilever deformation during loading. This measurement, processed by a force relation based on a superposition of deflections derived from Euler-Bernoulli bending theory and St Venant's torsion theory, provides the vertical, axial, and torsional force components simultaneously. Experimental results are compared to force predictions for the vertical and torsional components using macro-scale cantilevers under mass loading. An uncertainty analysis is also provided.

  8. Torsional electromechanical quantum oscillations in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cohen-Karni, Tzahi; Segev, Lior; Srur-Lavi, Onit; Cohen, Sidney R.; Joselevich, Ernesto

    2006-10-01

    Carbon nanotubes can be distinctly metallic or semiconducting depending on their diameter and chirality. Here we show that continuously varying the chirality by mechanical torsion can induce conductance oscillations, which can be attributed to metal-semiconductor periodic transitions. The phenomenon is observed in multiwalled carbon nanotubes, where both the torque and the current are shown to be carried predominantly by the outermost wall. The oscillation period with torsion is consistent with the theoretical shifting of the corners of the first Brillouin zone of graphene across different sub-bands allowed in the nanotube. Beyond a critical torsion, the conductance irreversibly drops due to torsional failure, allowing us to determine the torsional strength of carbon nanotubes. Carbon nanotubes could be ideal torsional springs for nanoscopic pendulums, because electromechanical detection of motion could replace the microscopic detection techniques used at present. Our experiments indicate that carbon nanotubes could be used as electronic sensors of torsional motion in nanoelectromechanical systems.

  9. Nonmetricity and torsion: facts and fancies in gauge approaches to gravity.

    NASA Astrophysics Data System (ADS)

    Baekler, P.; Hehl, F. W.; Mielke, E. W.

    In general relativity, the Riemannian connection of spacetime is symmetric and metric-compatible. If one relaxes at first the symmetry, one arrives at a Riemann-Cartan spacetime U4 with torsion. If one relaxes additionally, the metric-compatibility, then one is led to a metric-affine spacetime (L4,g) with nonmetricity and torsion. This paper presents an analysis of the (L4,g) spacetime and discusses in detail the case of a Poincaré gauge theory.

  10. Combined bending-torsion fatigue reliability. III

    NASA Technical Reports Server (NTRS)

    Kececioglu, D.; Chester, L. B.; Nolf, C. F., Jr.

    1975-01-01

    Results generated by three, unique fatigue reliability research machines which can apply reversed bending loads combined with steady torque are presented. AISI 4340 steel, grooved specimens with a stress concentration factor of 1.42 and 2.34, and Rockwell C hardness of 35/40 were subjected to various combinations of these loads and cycled to failure. The generated cycles-to-failure and stress-to-failure data are statistically analyzed to develop distributional S-N and Goodman diagrams. Various failure theories are investigated to determine which one represents the data best. The effects of the groove, and of the various combined bending-torsion loads, on the S-N and Goodman diagrams are determined. Two design applications are presented which illustrate the direct useability and value of the distributional failure governing strength and cycles-to-failure data in designing for specified levels of reliability and in predicting the reliability of given designs.

  11. On determining G using a cryogenic torsion pendulum

    NASA Astrophysics Data System (ADS)

    Newman, R. D.; Bantel, M. K.

    1999-06-01

    A measurement of G which will use a torsion pendulum in the `dynamic' (time-of-swing) mode, measuring the influence of field source masses on the pendulum's oscillation period, is being prepared at UC Irvine. Features of the design include: (i) operation at cryogenic temperature (2 K) to reduce thermal noise and increase frequency stability and for ease of magnetic shielding, (ii) large pendulum oscillation amplitudes to increase signal-to-noise ratio and reduce the effect of amplitude-determination error, (iii) use of a pair of source mass rings to produce an extremely uniform field gradient; and (iv) use of a thin quartz plate as a torsion pendulum to minimize sensitivity to pendulum density inhomogeneity and dimensional uncertainties. The `dynamic' method to be used has the great advantage of requiring no angular displacement measurement or calibrating force, but, as pointed out by Kuroda, the method is subject to systematic error associated with the anelastic properties of a torsion fibre. We demonstrate that, for the linear anelasticity discussed by Kuroda, the fractional error introduced by anelasticity in such measurements of G is bounded by 0icons/Journals/Common/le" ALT="le" ALIGN="TOP"/>icons/Journals/Common/delta" ALT="delta" ALIGN="TOP"/> G/Gicons/Journals/Common/le" ALT="le" ALIGN="TOP"/> 1/2 Q-1, where Q is the torsional oscillation quality factor of the pendulum. We report detailed studies of anelasticity in candidate fibre materials at low temperature, concluding that anelastic behaviour should not limit our G measurement at a level of a few ppm.

  12. Stability of Thin-Walled Tubes Under Torsion

    NASA Technical Reports Server (NTRS)

    Donnell, L H

    1935-01-01

    In this report a theoretical solution is developed for the torsion on a round thin-walled tube for which the walls become unstable. The results of this theory are given by a few simple formulas and curves which cover all cases. The differential equations of equilibrium are derived in a simpler form than previously found, it being shown that many items can be neglected.

  13. Nonlinear inelastic uniform torsion of bars by BEM

    Microsoft Academic Search

    E. J. Sapountzakis; V. J. Tsipiras

    2008-01-01

    In this paper the elastic–plastic uniform torsion analysis of simply or multiply connected cylindrical bars of arbitrary cross-section\\u000a taking into account the effect of geometric nonlinearity is presented employing the boundary element method. The stress–strain\\u000a relationship for the material is assumed to be elastic–plastic–strain hardening. The incremental torque–rotation relationship\\u000a is computed based on the finite displacement (finite rotation) theory, that

  14. Moduli Space of Torsional Manifolds

    E-print Network

    Melanie Becker; Li-Sheng Tseng; Shing-Tung Yau

    2007-10-04

    We characterize the geometric moduli of non-Kaehler manifolds with torsion. Heterotic supersymmetric flux compactifications require that the six-dimensional internal manifold be balanced, the gauge bundle be hermitian Yang-Mills, and also the anomaly cancellation be satisfied. We perform the linearized variation of these constraints to derive the defining equations for the local moduli. We explicitly determine the metric deformations of the smooth flux solution corresponding to a torus bundle over K3.

  15. Quantum Formulation of Fractional Orbital Angular Momentum

    E-print Network

    J. B. Goette; S. Franke-Arnold; R. Zambrini; Stephen M. Barnett

    2006-11-15

    The quantum theory of rotation angles (S. M. Barnett and D. T. Pegg, Phys. Rev. A, 41, 3427-3425 (1990)) is generalised to non-integer values of the orbital angular momentum. This requires the introduction of an additional parameter, the orientation of a phase discontinuity associated with fractional values of the orbital angular momentum. We apply our formalism to the propagation of light modes with fractional orbital angular momentum in the paraxial and non-paraxial regime.

  16. Quantum Formulation of Fractional Orbital Angular Momentum

    E-print Network

    Goette, J B; Franke-Arnold, S; Zambrini, R; Barnett, Stephen M.

    2006-01-01

    The quantum theory of rotation angles (S. M. Barnett and D. T. Pegg, Phys. Rev. A, 41, 3427-3425 (1990)) is generalised to non-integer values of the orbital angular momentum. This requires the introduction of an additional parameter, the orientation of a phase discontinuity associated with fractional values of the orbital angular momentum. We apply our formalism to the propagation of light modes with fractional orbital angular momentum in the paraxial and non-paraxial regime.

  17. Orbital angular momentum in phase space

    SciTech Connect

    Rigas, I. [Departamento de Optica, Facultad de Fisica, Universidad Complutense, 28040 Madrid (Spain); Sanchez-Soto, L.L., E-mail: lsanchez@fis.ucm.es [Departamento de Optica, Facultad de Fisica, Universidad Complutense, 28040 Madrid (Spain); Klimov, A.B. [Departamento de Fisica, Universidad de Guadalajara, 44420 Guadalajara, Jalisco (Mexico); Rehacek, J.; Hradil, Z. [Department of Optics, Palacky University, 17. Listopadu 12, 746 01 Olomouc (Czech Republic)

    2011-02-15

    Research Highlights: > We propose a comprehensive Weyl-Wigner formalism for the canonical pair angle-angular momentum. > We present a simple and useful toolkit for the practitioner. > We derive simple evolution equations in terms of a star product in the semiclassical limit. - Abstract: A comprehensive theory of the Weyl-Wigner formalism for the canonical pair angle-angular momentum is presented. Special attention is paid to the problems linked to rotational periodicity and angular-momentum discreteness.

  18. Dirac quasinormal modes of Chern-Simons and BTZ black holes with torsion

    NASA Astrophysics Data System (ADS)

    Bécar, Ramón; González, P. A.; Vásquez, Y.

    2014-01-01

    We study Chern-Simons black holes in d dimensions and we calculate analytically the quasinormal modes of fermionic perturbations. Also, we consider as background the five-dimensional Chern-Simons black hole with torsion and the BTZ black hole with torsion. We have found that the quasinormal modes depend on the highest power of curvature present in the Chern-Simons theory, such as that which occurs for the quasinormal modes of scalar perturbations. We also show that the effect of the torsion is to modify the real part of the quasinormal frequencies, which modify the oscillation frequency of the field for the five-dimensional case. However, for the BTZ black hole with torsion, the effect is to modify the imaginary part of these frequencies, that is, the relaxation time for the decay of the black hole perturbation. The imaginary part of the quasinormal frequencies is negative, which guarantees the stability of these black holes under fermionic field perturbations.

  19. Premotor neurons encode torsional eye velocity during smooth-pursuit eye movements

    NASA Technical Reports Server (NTRS)

    Angelaki, Dora E.; Dickman, J. David

    2003-01-01

    Responses to horizontal and vertical ocular pursuit and head and body rotation in multiple planes were recorded in eye movement-sensitive neurons in the rostral vestibular nuclei (VN) of two rhesus monkeys. When tested during pursuit through primary eye position, the majority of the cells preferred either horizontal or vertical target motion. During pursuit of targets that moved horizontally at different vertical eccentricities or vertically at different horizontal eccentricities, eye angular velocity has been shown to include a torsional component the amplitude of which is proportional to half the gaze angle ("half-angle rule" of Listing's law). Approximately half of the neurons, the majority of which were characterized as "vertical" during pursuit through primary position, exhibited significant changes in their response gain and/or phase as a function of gaze eccentricity during pursuit, as if they were also sensitive to torsional eye velocity. Multiple linear regression analysis revealed a significant contribution of torsional eye movement sensitivity to the responsiveness of the cells. These findings suggest that many VN neurons encode three-dimensional angular velocity, rather than the two-dimensional derivative of eye position, during smooth-pursuit eye movements. Although no clear clustering of pursuit preferred-direction vectors along the semicircular canal axes was observed, the sensitivity of VN neurons to torsional eye movements might reflect a preservation of similar premotor coding of visual and vestibular-driven slow eye movements for both lateral-eyed and foveate species.

  20. Primary splenic torsion in a Boston terrier.

    PubMed

    OHTA, Hiroshi; TAKAGI, Satoshi; MURAKAMI, Masahiro; SASAKI, Noboru; YOSHIKAWA, Muneyoshi; NAKAMURA, Kensuke; HWANG, Shiang-Jyi; YAMASAKI, Masahiro; TAKIGUCHI, Mitsuyoshi

    2009-11-01

    A 7-year-old female Boston terrier was referred to Hokkaido University Veterinary Teaching Hospital with a history of hemoglobinuria and anemia for several days. Abdominal radiographs showed splenomegaly, and ultrasonography revealed a hypoechoic splenic parenchyma with interspersed linear echoes consistent with the ultrasonographic appearance of splenic torsion. Ultrasonography and computed tomography (CT) indicated a C-shaped spleen. Exploratory laparotomy confirmed the diagnosis of splenic torsion. A splenectomy was performed, and the dog recovered well without complications. This is the first report of splenic torsion in Boston terriers, and the usefulness of ultrasonographic and CT findings of the splenic torsion was also confirmed. PMID:19959908

  1. Torsion and Supersymmetry Breaking

    E-print Network

    Albion Lawrence; Tobias Sander; Michael B. Schulz; Brian Wecht

    2008-06-24

    We identify the auxiliary fields in the hypermultiplets of type IIB string theory compactified on a Calabi-Yau manifold, using a combination of worldsheet and supergravity techniques. The SUSY-breaking squark and gaugino masses in type IIB models depend on these auxiliary fields, which parametrize deformations away from a pure Calabi-Yau compactification to one with NS-NS 3-form flux and SU(3) x SU(3) structure. Worldsheet arguments show that such compactifications are generically globally nongeometric. Our results, combined with earlier results for type IIA compactifications, imply that these deformations are the mirrors of NS-NS 3-form flux, in accord with work from the supergravity point of view. Using the worldsheet current algebra, we explain why mirror symmetry may continue to hold in the presence of fluxes breaking the symmetries (e.g., (2,2) SUSY) on which mirror symmetry is typically taken to depend. Finally, we give evidence that nonperturbative worldsheet effects (such as worldsheet instantons) provide important corrections to the supergravity picture in the presence of auxiliary fields for Kahler moduli.

  2. Coupled lateral-torsional-axial vibrations of a helical gear-rotor-bearing system

    NASA Astrophysics Data System (ADS)

    Li, Chao-Feng; Zhou, Shi-Hua; Liu, Jie; Wen, Bang-Chun

    2014-10-01

    Considering the axial and radial loads, a mathematical model of angular contact ball bearing is deduced with Hertz contact theory. With the coupling effects of lateral, torsional and axial vibrations taken into account, a lumped-parameter nonlinear dynamic model of helical gearrotor-bearing system (HGRBS) is established to obtain the transmission system dynamic response to the changes of different parameters. The vibration differential equations of the drive system are derived through the Lagrange equation, which considers the kinetic and potential energies, the dissipative function and the internal/external excitation. Based on the Runge-Kutta numerical method, the dynamics of the HGRBS is investigated, which describes vibration properties of HGRBS more comprehensively. The results show that the vibration amplitudes have obvious fluctuation, and the frequency multiplication and random frequency components become increasingly obvious with changing rotational speed and eccentricity at gear and bearing positions. Axial vibration of the HGRBS also has some fluctuations. The bearing has self-variable stiffness frequency, which should be avoided in engineering design. In addition, the bearing clearance needs little attention due to its slightly discernible effect on vibration response. It is suggested that a careful examination should be made in modelling the nonlinear dynamic behavior of a helical gear-rotor-bearing system.

  3. Quantum formulation of fractional orbital angular momentum

    Microsoft Academic Search

    J. B. Götte; S. Franke-Arnold; R. Zambrini; Stephen M. Barnett

    2007-01-01

    The quantum theory of rotation angles (S. M. Barnett and D. T. Pegg, Phys. Rev. A, 41, 3427-3425 (1990)) is generalised to non-integer values of the orbital angular momentum. This requires the introduction of an additional parameter, the orientation of a phase discontinuity associated with fractional values of the orbital angular momentum. We apply our formalism to the propagation of

  4. Torsional Buckling and Writhing Dynamics of Elastic Cables and DNA

    SciTech Connect

    Goyal, S; Perkins, N C; Lee, C L

    2003-02-14

    Marine cables under low tension and torsion on the sea floor can undergo a dynamic buckling process during which torsional strain energy is converted to bending strain energy. The resulting three-dimensional cable geometries can be highly contorted and include loops and tangles. Similar geometries are known to exist for supercoiled DNA and these also arise from the conversion of torsional strain energy to bending strain energy or, kinematically, a conversion of twist to writhe. A dynamic form of Kirchhoff rod theory is presented herein that captures these nonlinear dynamic processes. The resulting theory is discretized using the generalized-method for finite differencing in both space and time. The important kinematics of cross-section rotation are described using an incremental rotation ''vector'' as opposed to traditional Euler angles or Euler parameters. Numerical solutions are presented for an example system of a cable subjected to increasing twist at one end. The solutions show the dynamic evolution of the cable from an initially straight element, through a buckled element in the approximate form of a helix, and through the dynamic collapse of this helix through a looped form.

  5. 2D Gravity with Torsion, Oriented Matroids and 2+2 Dimensions

    E-print Network

    J. A. Nieto; E. A. Leon

    2009-09-22

    We find a link between oriented matroid theory and 2d gravity with torsion. Our considerations may be useful in the context of noncommutative phase space in a target spacetime of signature (2+2) and in a possible theory of gravity ramification.

  6. Direct torsion control of flexible shaft in an observer-based discrete-time sliding mode

    Microsoft Academic Search

    P. Koronki; H. Hashimoto; V. Utkin

    1998-01-01

    This paper presents a new speed control method for a two-mass system coupled by a flexible shaft. Two control loops are proposed; the outer angular speed control loop calculates the reference signal for the inner loop, where the torsion of the shaft is handled as a variable under control. In this paper, the observer-based discrete-time sliding-mode (ODSM) control implementation and

  7. An explanation of forms of planetary orbits and estimation of angular shift of the Mercury' perihelion using the statistical theory of gravitating spheroidal bodies

    NASA Astrophysics Data System (ADS)

    Krot, A. M.

    2013-09-01

    This work develops a statistical theory of gravitating spheroidal bodies to calculate the orbits of planets and explore forms of planetary orbits with regard to the Alfvén oscillating force [1] in the Solar system and other exoplanetary systems. The statistical theory of formation of gravitating spheroidal bodies has been proposed in [2]-[5]. Starting the conception for forming a spheroidal body inside a gas-dust protoplanetary nebula, this theory solves the problem of gravitational condensation of a gas-dust protoplanetary cloud with a view to planetary formation in its own gravitational field [3] as well as derives a new law of the Solar system planetary distances which generalizes the wellknown laws [2], [3]. This work also explains an origin of the Alfvén oscillating force modifying forms of planetary orbits within the framework of the statistical theory of gravitating spheroidal bodies [5]. Due to the Alfvén oscillating force moving solid bodies in a distant zone of a rotating spheroidal body have elliptic trajectories. It means that orbits for the enough remote planets from the Sun in Solar system are described by ellipses with focus in the origin of coordinates and with small eccentricities. The nearby planet to Sun named Mercury has more complex trajectory. Namely, in case of Mercury the angular displacement of a Newtonian ellipse is observed during its one rotation on an orbit, i.e. a regular (century) shift of the perihelion of Mercury' orbit occurs. According to the statistical theory of gravitating spheroidal bodies [2]-[5] under the usage of laws of celestial mechanics in conformity to cosmogonic bodies (especially, to stars) it is necessary to take into account an extended substance called a stellar corona. In this connection the stellar corona can be described by means of model of rotating and gravitating spheroidal body [5]. Moreover, the parameter of gravitational compression ? of a spheroidal body (describing the Sun, in particular) has been estimated on the basis of the linear size of its kernel, i.e. the thickness of a visible part of the solar corona. Really, NASA' astronomer S. Odenwald in his notice «How thick is the solar corona?» wrote: "The corona actually extends throughout the entire solar system as a "wind" of particles, however, the densist parts of the corona is usually seen not more than about 1-2 solar radii from the surface or about 690,000 to 1.5 million kilometers at the equator. Near the poles, it seems to be a bit flatter..." [6]. In the fact, as mentioned in [5], a recession of plots of dependences of relative brightness of components of spectrum of the Solar corona occurs on distance of 3-3.5 radii from the center, i.e. on 2-2.5 radii from the edge of the solar disk. Thus, accepting thickness of a visible part of the solar corona equal to ? = 2R (here R is radius of the solar disk) we find that r* = R + ? = 3R , where r* =1/ ? . In other words, the parameter of gravitational compression 2 ? =1/ r* of a spheroidal body in case of the Sun with its corona (for which the equatorial radius ofdisk R = 6.955?108 m) can be estimated by the value [2]-[5]: 2.29701177718 10 (m ) (3 ) 1 19 2 2 = ? ? - - R ? . (1) So, the procedure of finding ? is based on the known 3? -rule in the statistical theory. Really, as shown in the monograph [5], namely the solar corona accounting under calculation of perturbed orbit of the planet of Mercury allows to find the estimation of a displacement of perihelion of Mercury' orbit for the one period within the framework of the statistical theory of gravitating spheroidal bodies. As it is known, on a way of specification of the law of Newton using the general relativity theory the Mercury problem solving was found [5]. Nevertheless, from a common position of the statistical theory of gravitating spheroidal bodies the points of view as Leverrier (about existence of an unknown matter) and Einstein (about insufficiency of the theory of Newton) practically differ nothing. Really, there exist plasma as well as gas-dust substance

  8. Gauge invariant coupling of fields to torsion: A string inspired model

    SciTech Connect

    Bhattacharjee, Srijit; Chatterjee, Ayan [Theory Group, Saha Institute of Nuclear Physics, Kolkata 700064 (India); The Institute of Mathematical Sciences, CIT Campus, Taramani, Chennai-600113 (India)

    2011-05-15

    In a consistent heterotic string theory, the Kalb-Ramond field, which is the source of space-time torsion, is augmented by Yang-Mills and gravitational Chern-Simons terms. When compactified to 4 dimensions and in the field theory limit, such additional terms give rise to interactions with interesting astrophysical predictions like rotation of plane of polarization for electromagnetic and gravitational waves. On the other hand, if one is also interested in coupling 2- or 3-form (Abelian or non-Abelian) gauge fields to torsion, one needs another class of interaction. In this paper, we shall study this interaction and offer some astrophysical and cosmological predictions. We explicitly calculate the Coleman-Weinberg potential for this theory. We also comment on the possibility of such terms in loop quantum gravity where, if the Barbero-Immirzi parameter is promoted to a field, acts as a source for torsion.

  9. TWISTING COCHAINS AND HIGHER TORSION KIYOSHI IGUSA

    E-print Network

    Igusa, Kiyoshi

    . This paper gives a short summary of the central role played by Ed Brown's "twisting cochains" in higher Franz and fiber F are finite cell complexes. It is given by the tensor product of chain complexes for F and B 19J10, 55R40. Key words and phrases. higher Franz-Reidemeister torsion, higher analytic torsion, A

  10. A Novel Permanent Magnetic Angular Acceleration Sensor.

    PubMed

    Zhao, Hao; Feng, Hao

    2015-01-01

    Angular acceleration is an important parameter for status monitoring and fault diagnosis of rotary machinery. Therefore, we developed a novel permanent magnetic angular acceleration sensor, which is without rotation angle limitations and could directly measure the instantaneous angular acceleration of the rotating system. The sensor rotor only needs to be coaxially connected with the rotating system, which enables convenient sensor installation. For the cup structure of the sensor rotor, it has a relatively small rotational inertia. Due to the unique mechanical structure of the sensor, the output signal of the sensor can be directed without a slip ring, which avoids signal weakening effect. In this paper, the operating principle of the sensor is described, and simulated using finite element method. The sensitivity of the sensor is calibrated by torsional pendulum and angle sensor, yielding an experimental result of about 0.88 mV/(rad·s-2). Finally, the angular acceleration of the actual rotating system has been tested, using both a single-phase asynchronous motor and a step motor. Experimental result confirms the operating principle of the sensor and indicates that the sensor has good practicability. PMID:26151217

  11. Some solutions with torsion in Chern-Simons gravity and observable effects

    E-print Network

    F. Canfora

    2008-07-02

    It is shown that in all odd dimensional Chern-Simons theories states in which the torsion is non zero (but it can approach smoothly to zero outside suitable regions) do exist. Some possible observational effects related to neutrino oscillations are pointed out. In the theory of continuum media (in which suitable defects can be described by localized non vanishing torsion) "the gravitational intuition" is a rather useful tool to describe the physical effects of such defects. A possible astrophysical application is shortly described.

  12. Torsion of Noncircular Composite Cylinders

    NASA Technical Reports Server (NTRS)

    Rouse, Marshall; Hyer, Michael W.; Haynie, Waddy T.

    2005-01-01

    The paper presents a brief overview of the predicted deformation and failure characteristics of noncircular composite cylinders subjected to torsion. Using a numerical analysis, elliptical cylinders with a minor-to-major diameter ratio of 0.7 are considered. Counterpart circular cylinders with the same circumference as the elliptical cylinders are included for comparison. The cylinders are constructed of a medium-modulus graphite-epoxy material in a quasi-isotropic lay-up. Imperfections generated from the buckling mode shapes are included in the initial cross-sectional geometry of the cylinders. Deformations until first fiber failure, as predicted using the maximum stress failure criterion and a material degradation scheme, are presented. For increasing levels of torsion, the deformations of the elliptical cylinders, in the form of wrinkling of the cylinder wall, occur primarily in the flatter regions of the cross section. By comparison the wrinkling deformations of the circular cylinders are more uniformly distributed around the circumference. Differences in the initial failure and damage progression and the overall torque vs. twist relationship between the elliptical and circular cylinders are presented. Despite differences in the response as the cylinders are being loaded, at first fiber failure the torque and twist for the elliptical and circular cylinders nearly coincide.

  13. Brane World black holes in Teleparallel Theory Equivalent to General Relativity and their Killing vectors, Energy, Momentum and Angular-Momentum

    E-print Network

    Gamal G. L. Nashed

    2009-10-27

    The energy-momentum tensor, which is coordinate independent, is used to calculate energy, momentum and angular-momentum of two different tetrad fields. Although, the two tetrad fields reproduce the same space-time their energies are different. Therefore, a regularized expression of the gravitational energy-momentum tensor of the teleparallel equivalent of general relativity, (TEGR), is used to make the energies of the two tetrad fields equal. The definition of the gravitational energy-momentum is used to investigate the energy within the external event horizon. The components of angular-momentum associated with these space-times are calculated. In spite that we use a static space-times, we get a non-zero component of angular-momentum! Therefore, we derive the killing vectors associated with these space-times using the definition of the Lie derivative of a second rank tensor in the framework of the TEGR to make the picture more clear.

  14. A first-order secular theory for the post-Newtonian two-body problem with spin - II. A complete solution for the angular coordinates in the restricted case

    NASA Astrophysics Data System (ADS)

    Biscani, Francesco; Carloni, Sante

    2015-01-01

    Building on the results of a previous paper, we compute for the first time a full first-order perturbative solution for the angular coordinates in the restricted post-Newtonian two-body problem with spin. The analytical integration of the angular coordinates, based on the theory of the Weierstrassian functions, allows us to investigate thoroughly the spin-orbit and spin-spin interactions, and to derive several new results. The application of our solution to a selection of idealized physical systems of interest reveals a rich variety of dynamical behaviours driven by purely relativistic effects. In particular, we highlight a new relativistic nutational motion resulting from the combined spin-orbit and spin-spin interactions.

  15. Angular momentum and the polar basis of harmonic oscillator

    E-print Network

    Paris-Sud XI, Université de

    1 Angular momentum and the polar basis of harmonic oscillator M. Hage-Hassan Université Libanaise for angular momentum but with the polar basis of harmonic oscillator as a starting point. We derive by a new momentum. 1-Introduction The theory of angular momentum occupies an important position in the development

  16. Stability of tapered I-Beams under torsional moments

    Microsoft Academic Search

    Jong-Dar Yau

    2006-01-01

    Previous investigations on the buckling of torsionally loaded bars indicate that the critical loads depend upon the mechanical device that generates the end torque. By representing the torsional moment on an I-section as the combination of St. Venant and warping torsions, this study presents a finite element model for buckling analysis of tapered I-beams subjected to torsional moments. Regarding a

  17. Torsion Balance Search for Lorentz-invariance, Dark

    E-print Network

    Torsion Balance Search for Lorentz-invariance, Dark Energy and Dark Matter Claire Cramer AAPT of unpolarized matter another particle's spin #12;Torsion balances Coulomb's torsion balance: A high precision-plated · magnetically shielded · 4 mirrors 2.6 cm #12;#12;The torsion balance apparatus feet pendulum magnetic shielding

  18. September 12, 2007 THE ISOMORPHISM PROBLEM FOR TORSION-FREE

    E-print Network

    September 12, 2007 THE ISOMORPHISM PROBLEM FOR TORSION-FREE ABELIAN GROUPS IS ANALYTIC COMPLETE. ROD DOWNEY AND ANTONIO MONTALB´AN Abstract. We prove that the isomorphism problem for torsion-free for countable torsion-free Abelian groups. The question we ask is, given two countable torsion-free Abelian

  19. A Kinetic Theory for Nonanalog Monte Carlo Particle Transport Algorithms: Exponential Transform with Angular Biasing in Planar-Geometry Anisotropically Scattering Media

    NASA Astrophysics Data System (ADS)

    Ueki, Taro; Larsen, Edward W.

    1998-09-01

    We show that Monte Carlo simulations of neutral particle transport in planar-geometry anisotropically scattering media, using the exponential transform with angular biasing as a variance reduction device, are governed by a new "Boltzmann Monte Carlo" (BMC) equation, which includes particle weight as an extra independent variable. The weight moments of the solution of the BMC equation determine the moments of the score and the mean number of collisions per history in the nonanalog Monte Carlo simulations. Therefore, the solution of the BMC equation predicts the variance of the score and the figure of merit in the simulation. Also, by (i) using an angular biasing function that is closely related to the "asymptotic" solution of the linear Boltzmann equation and (ii) requiring isotropic weight changes at collisions, we derive a new angular biasing scheme. Using the BMC equation, we propose a universal "safe" upper limit of the transform parameter, valid for any type of exponential transform. In numerical calculations, we demonstrate that the behavior of the Monte Carlo simulations and the performance predicted by deterministically solving the BMC equation agree well, and that the new angular biasing scheme is always advantageous.

  20. Testicular torsion in the older patient

    SciTech Connect

    Perry, S.; Hoopingarner, D.; Askins, D.

    1983-05-01

    A 40-year-old man presented with severe right-sided scrotal pain and was proven to have a 720-degree right testicular torsion. Fewer than 50 documented cases of testicular torsion have been reported in men over the age of thirty. The anatomical predisposition for torsion generally selects these individuals early in life. Rapid diagnosis allowed for surgical correction and testicular salvage. We outline an expedient diagnostic approach for these difficult cases with use of the Doppler ultrasound and the technetium (99mTc) testicular scan.

  1. An experimental and theoretical study of a coupling mechanism between longitudinal and torsional drillstring vibrations at the bit

    SciTech Connect

    Aarrestad, T.V.; Kyllingstad, A.

    1988-03-01

    A mechanism that couples longitudinal and torsional drillstring vibrations at the bit was studied. Torsional vibrations are associated with dynamic variations of the rotational bit speed. When a roller bit runs over a multilobed pattern, these speed variations have been shown to affect the input of longitudinal vibrations. The theory for this coupling mechanisms is verified experimentally by high-rate data of near-bit accelerations and torque recorded in a 1000-m (3,280-ft) -deep well.

  2. Quantum gravity with torsion and non-metricity

    E-print Network

    Pagani, Carlo

    2015-01-01

    We study the renormalization of theories of gravity with an arbitrary (torsionful and non-metric) connection. The class of actions we consider is of the Palatini type, including the most general terms with up to two derivatives of the metric, but no derivatives of the connection. It contains 19 independent parameters. We calculate the one loop beta functions of these parameters and find their fixed points. The Holst subspace is discussed in some detail and found not to be stable under renormalization. Some possible implications for ultraviolet and infrared gravity are discussed.

  3. Quantum gravity with torsion and non-metricity

    E-print Network

    Carlo Pagani; Roberto Percacci

    2015-06-09

    We study the renormalization of theories of gravity with an arbitrary (torsionful and non-metric) connection. The class of actions we consider is of the Palatini type, including the most general terms with up to two derivatives of the metric, but no derivatives of the connection. It contains 19 independent parameters. We calculate the one loop beta functions of these parameters and find their fixed points. The Holst subspace is discussed in some detail and found not to be stable under renormalization. Some possible implications for ultraviolet and infrared gravity are discussed.

  4. The Effect of Acute Superior Oblique Palsy on Torsional Optokinetic Nystagmus in Monkeys

    PubMed Central

    Shan, Xiaoyan; Tian, Jing; Ying, Howard S.; Walker, Mark F.; Guyton, David; Quaia, Christian; Optican, Lance M.; Tamargo, Rafael J.; Zee, David S.

    2008-01-01

    Purpose To investigate the effects of acquired superior oblique palsy (SOP) and corrective strabismus surgery on torsional optokinetic nystagmus (tOKN) in monkeys. Methods The trochlear nerve was severed intracranially in two rhesus monkeys (M1 and M2). For each monkey, more than 4 months after the SOP, the ipsilateral inferior oblique muscle was denervated and extirpated. For M2, 4 months later, the contralateral inferior rectus muscle was recessed by 2 mm. tOKN was elicited during monocular viewing of a rotating stimulus that was rear projected onto a screen 43.5 cm in front of the animal. Angular rotation of the stimulus about the center was 40 deg/s clockwise or counterclockwise. Results The main findings after trochlear nerve sectioning were (1) the amplitude and peak velocity of torsional quick and slow phases of the paretic eye was less than that in the normal eye for both intorsion and extorsion, and (2) the vertical motion of the paretic eye increased during both torsional slow and quick phases. After corrective inferior oblique surgery, both of these effects were even greater. Conclusions Acquired SOP and corrective inferior oblique–weakening surgery create characteristic patterns of change in tOKN that reflect alterations in the dynamic properties of the extraocular muscles involved in eye torsion. tOKN also provides information complementary to that provided by the traditional Bielschowsky head-tilt test and potentially can help distinguish among different causes of vertical ocular misalignment. PMID:18385059

  5. Doppler ultrasound diagnosis of testicular cord torsion.

    PubMed

    Milleret, R

    1976-12-01

    The author confirmed clinical diagnosis of torsion of the testis with Doppler ultrasound flowmeters in 12 of 15 patients. Doppler examination in addition to clinical examination was more accurate than clinical examination alone. Problems were encountered when examining newborns, but progress in probe technology may yield better results in this area. The Doppler technique is a useful adjunct in the management of torsion of the testis. PMID:825541

  6. Flow in a torsionally oscillating filled cylinder

    NASA Technical Reports Server (NTRS)

    Schafer, C. F.

    1983-01-01

    The flow of a liquid in a completely filled cylinder undergoing torsional oscillations about its longitudinal symmetry axis was studied analytically and experimentally. The objective of the studies was to determine the efficacy of the torsional oscillations in mixing the confined liquid. Flow was found to be confined primarily to toroidal cells at the ends of the cylinder. Cell thickness was about equal to the cylinder radius. The use of baffles at the end walls was shown to enhance the mixing process.

  7. Branched Spines of 3-Manifolds and Reidemeister Torsion of Euler Structures

    E-print Network

    Costantino, Francesco

    Branched Spines of 3-Manifolds and Reidemeister Torsion of Euler Structures Gennaro Amendola an elementary and self-contained technique. Namely, we use the theory of branched standard spines to express is that of branched standard spines, originally developed in [1]. This technique was already used in [2] to give

  8. Localization of the Einstein group and a nonsingular cosmological model of space-time with torsion

    Microsoft Academic Search

    V. N. Tunyak

    1986-01-01

    We consider an Einstein-invariant gauge theory of gravitation (EGT), obtained by localizing the group of motions of a homogeneous static Einstein Universe. Taking into account the cosmological term, we find exact solutions of EGT are as nonsingular homogeneous Isotropic cosmological models with both the metric and the torsion regular. It is shown that EGT satisfies the principle of correspondence with

  9. Localization of the Einstein group and a nonsingular cosmological model of space-time with torsion

    Microsoft Academic Search

    Tunyak

    1987-01-01

    The authors consider an Einstein-invariant gauge theory of gravitation (EGT), obtained by localizing the group of motions of a homogeneous static Einstein Universe. Taking into account the cosmological term, they find exact solutions of EGT are as nonsingular homogeneous isotropic cosmological models with both the metric and the torsion regular. It is shown that EGT satisfies the principle of correspondence

  10. Quantum formulation of fractional orbital angular momentum

    Microsoft Academic Search

    J. B. GÖTTE; S. Franke-Arnold; R. Zambrini; Stephen M. Barnett

    2007-01-01

    The quantum theory of rotation angles [S.M. Barnett and D.T. Pegg, Phys. Rev. A 41 3427 (1990)] is generalized to non-integer values of the orbital angular momentum. This requires the introduction of an additional parameter, the orientation of a phase discontinuity associated with fractional values of the orbital angular momentum. We apply our formalism to the propagation of light modes

  11. Beam and Torsion Tests of Aluminum-alloy 61S-T Tubing

    NASA Technical Reports Server (NTRS)

    Moore, R L; Holt, Marshall

    1942-01-01

    Tests were made to determine the effect of length and the effect of ratios of diameter to wall thickness upon the flexural and torsional moduli of failure of 61S-T aluminum-alloy tubing. The moduli of failure in bending, as determined by tests in which the tubing was loaded on the neutral axis at the one-third points of the span, were found to bear an approximately linear relationship with diameter-thickness ratio and were practically independent of span within the limits investigated. Empirical equations are given describing the relations obtained. The moduli of failure in torsion were found to be dependent upon length as well as upon diameter-thickness ratios. Empirical equations are given for predicting strengths within the range of plastic buckling. Within the elastic range, available torsion theories were found to be satisfactory.

  12. Cross-shaped torsional spring

    DOEpatents

    Williamson, M.M.; Pratt, G.A.

    1999-06-08

    The invention provides an elastic actuator consisting of a motor and a motor drive transmission connected at an output of the motor. An elastic element is connected in series with the motor drive transmission, and this elastic element is positioned to alone support the full weight of any load connected at an output of the actuator. A single force transducer is positioned at a point between a mount for the motor and an output of the actuator. This force transducer generates a force signal, based on deflection of the elastic element, that indicates force applied by the elastic element to an output of the actuator. An active feedback force control loop is connected between the force transducer and the motor for controlling the motor. This motor control is based on the force signal to deflect the elastic element an amount that produces a desired actuator output force. The produced output force is substantially independent of load motion. The invention also provides a torsional spring consisting of a flexible structure having at least three flat sections each connected integrally with and extending radially from a central section. Each flat section extends axially along the central section from a distal end of the central section to a proximal end of the central section. 30 figs.

  13. Cross-shaped torsional spring

    DOEpatents

    Williamson, Matthew M. (Boston, MA); Pratt, Gill A. (Lexington, MA)

    1999-06-08

    The invention provides an elastic actuator consisting of a motor and a motor drive transmission connected at an output of the motor. An elastic element is connected in series with the motor drive transmission, and this elastic element is positioned to alone support the full weight of any load connected at an output of the actuator. A single force transducer is positioned at a point between a mount for the motor and an output of the actuator. This force transducer generates a force signal, based on deflection of the elastic element, that indicates force applied by the elastic element to an output of the actuator. An active feedback force control loop is connected between the force transducer and the motor for controlling the motor. This motor control is based on the force signal to deflect the elastic element an amount that produces a desired actuator output force. The produced output force is substantially independent of load motion. The invention also provides a torsional spring consisting of a flexible structure having at least three flat sections each connected integrally with and extending radially from a central section. Each flat section extends axially along the central section from a distal end of the central section to a proximal end of the central section.

  14. Communication: direct comparison between theory and experiment for correlated angular and product-state distributions of the ground-state and stretching-excited O((3)P) + CH4 reactions.

    PubMed

    Czakó, Gábor

    2014-06-21

    Motivated by a recent experiment [H. Pan and K. Liu, J. Chem. Phys. 140, 191101 (2014)], we report a quasiclassical trajectory study of the O((3)P) + CH4(vk = 0, 1) ? OH + CH3 [k = 1 and 3] reactions on an ab initio potential energy surface. The computed angular distributions and cross sections correlated to the OH(v = 0, 1) + CH3(v = 0) coincident product states can be directly compared to experiment for O + CH4(v3 = 0, 1). Both theory and experiment show that the ground-state reaction is backward scattered, whereas the angular distributions shift toward sideways and forward directions upon antisymmetric stretching (v3) excitation of the reactant. Theory predicts similar behavior for the O + CH4(v1 = 1) reaction. The simulations show that stretching excitation enhances the reaction up to about 15 kcal/mol collision energy, whereas the O + CH4(vk = 1) reactions produce smaller cross sections for OH(v = 1) + CH3(v = 0) than those of O + CH4(v = 0) ? OH(v = 0) + CH3(v = 0). The former finding agrees with experiment and the latter awaits for confirmation. The computed cold OH rotational distributions of O + CH4(v = 0) are in good agreement with experiment. PMID:24952515

  15. Combined bending and torsional fatigue of woven roving GRP

    SciTech Connect

    Aboul Wafa, M.N.; Hamdy, A.H.; El-Midany, A.A. [Alexandria Univ. (Egypt). Mechanical Engineering Dept.

    1997-04-01

    A study of biaxial fatigue of woven roving glass reinforced polyester (GRP) subjected to in-phase and out-of-phase cyclic bending and torsional moments is presented. To evaluate failure theories for this material, tests were conducted on two fiber orientations [0, 90] and [45, {minus}45] tubes. The results showed that for [0, 90] composites the S-N curves in pure bending and in pure torsion are sufficient to predict life. For [45, {minus}45] tubes, the value of the normal stress interaction component of the strength tensor, H{sub 12}, has to be obtained. If the ratio of the global flexural stress amplitude, A, to the accompanied global shear stress, B, is less than 2, the value of H{sub 12} may be taken as presented by Tsai-Hahn theory. But, if A/B {ge} 2, the value of H{sub 12} has to be obtained from [45, {minus}45] pure bending S-N curve, since the failure mode is a combination of interfacial shear and matrix failure. The out-of-phase loading results showed that the life of the specimens at high stress levels is less than that for the in-phase loading with the same peak values A and B.

  16. Angular Acceleration without Torque?

    ERIC Educational Resources Information Center

    Kaufman, Richard D.

    2012-01-01

    Hardly. Just as Robert Johns qualitatively describes angular acceleration by an internal force in his article "Acceleration Without Force?" here we will extend the discussion to consider angular acceleration by an internal torque. As we will see, this internal torque is due to an internal force acting at a distance from an instantaneous center.

  17. CONVERVATION OF ANGULAR MOMENTUM A rotating bicycle wheel has angular

    E-print Network

    CONVERVATION OF ANGULAR MOMENTUM A rotating bicycle wheel has angular momentum, which is a property a larger angular momentum at a given speed. Angular momentum is characterized by both size and direction momentum. This means that any change in angular momentum within the system must be accompanied by an equal

  18. Mechanical behavior of twinned SiC nanowires under combined tension-torsion and compression-torsion strain

    SciTech Connect

    Li, Zhijie; Wang, Shengjie; Wang, Zhiguo; Zu, Xiaotao T.; Gao, Fei; Weber, William J.

    2010-07-01

    The mechanical behavior of twinned silicon carbide (SiC) nanowires under combined tension-torsion and compression-torsion is investigated using molecular dynamics simulations with an empirical potential. The simulation results show that both the tensile failure stress and buckling stress decrease under combined tension-torsional and combined compression-torsional strain, and they decrease with increasing torsional rate under combined loading. The torsion rate has no effect on the elastic properties of the twinned SiC nanowires. The collapse of the twinned nanowires takes place in a twin stacking fault of the nanowires.

  19. Anisotropic bending-torsion coupling for warping in a non-linear beam

    Microsoft Academic Search

    S. Klinkel; S. Govindjee

    2003-01-01

    MEMS devices made from single crystal silicon often contain rod-like structures that are operated in bending and\\/or torsion.\\u000a The design of these devices usually relies upon simple mechanical theories that ignore the coupling between these two modes\\u000a of operation. In this paper, we develop a theory that is capable of accounting for the material coupling in the bending and\\u000a twisting

  20. Transvaginal ovarian cystectomy for adnexal torsion during pregnancy.

    PubMed

    Gaspar-Oishi, Maria A; Kawelo, Roxanne M; Bartholomew, Marguerite Lisa; Aeby, Tod

    2012-01-01

    Ovarian torsion requiring surgical intervention in pregnancy is rare. Herein is reported a case of ovarian torsion that was managed by transvaginal ovarian cystectomy in a 27 week gravid patient. PMID:22381973

  1. Torsion system for creep testing with multiple stress reversals

    NASA Technical Reports Server (NTRS)

    Lilienthal, P. A.

    1969-01-01

    Torsion system proves exploratory data on accelerated creep due to multiple stress reversals. Torsional testing of tubular specimens is best suited for reversed stress creep tests since large strains are obtainable while maintaining specimen geometry.

  2. Ocular torsional movements in normal humans.

    PubMed

    Kushner, B J; Kraft, S

    1983-06-01

    We conducted three studies of compensatory ocular torsional movements in normal human subjects, using changes in the axis of astigmatism, afterimages, and direct observation with cinematography. Measurements of changes in the axis of astigmatism and the subjects' subjective perception of afterimages with a superimposed Maddox rod showed a partial compensatory intorsion on head tilt to the ipsilateral side and extorsion on head tilt to the contralateral side. Cinematography demonstrated that the eye lags behind the head in a slow rolling movement as the head is tilted. Periodic rotary movements in the direction of the head tilt partially correct the lag and result in a partial compensatory torsion. A fourth experiment excluded false torsion as an artifact in these studies. PMID:6859183

  3. Active structures to reduce torsional vibrations

    NASA Astrophysics Data System (ADS)

    Matthias, M.; Schlote, D.; Atzrodt, H.

    2013-03-01

    This paper describes the development of different active measures to reduce torsional vibrations in power trains. The measures are based on concepts developed for active mounts to reduce the transmission of structure-borne sound. To show the potential of these active measures and investigate their mode of operation to influence torsional vibrations, numerical simulations of powertrains with different active measures were done. First experimental results from tests on an experimental (reduced size) power train were used to align the numerical models. The work was done within the project 'LOEWE-Zentrum AdRIA: Adaptronik - Research, Innovation, Application' funded by the German federal state of Hessen, and the Project AKTos: 'Active control of torsional vibrations by coupling elements' placed in the research Framework program 'Navigation and Maritime Technology for the 21st Century' funded by the German Federal Ministry of Economics and Technology.

  4. Resonant Frequency Change of Torsional Oscillator Induced by Solid 4He in Torsion Rod

    NASA Astrophysics Data System (ADS)

    Aoki, Yuki; Iwasa, Izumi; Miura, Takeru; Takahashi, Daisuke; Yamaguchi, Akira; Murakawa, Satoshi; Okuda, Yuichi

    2014-08-01

    The contribution of solid 4He contained in the torsion rod of a torsional oscillator to its resonant frequency is investigated using a modified torsional oscillator. The purpose of the present study is to discriminate between two possible contributions to the resonant frequency of the torsional oscillator, which abruptly increases below ˜0.2 K. The first possible contribution is the elastic property change of solid 4He in the torsion rod (i.e., shear modulus increase), and the second possible contribution is mass decoupling by the supersolid transition of solid 4He in the oscillating body (i.e., a decrease in the momentum inertia). A torsional oscillator that has no hollow space for solid 4He in the body was constructed, and its resonant frequency and Q-factor were compared to those of the conventional oscillator. The shear modulus contributions of solid 4He in the torsion rod were identical, but the momentum inertias of solid 4He in the oscillating body were quite different between the two oscillators. Surprisingly, the observed frequency behavior and magnitude of the two oscillators were comparable. This finding indicates that the resonant frequency increase observed in the torsional oscillator originates from the increase in the shear modulus of solid 4He in the torsion rod, rather than from the momentum inertia decrease of the solid 4He in the oscillating body. The temperature dependence of the increase in the shear modulus of solid 4He was well reproduced by the dislocation-vibration model with a much lower 3He impurity concentration than that of commercially available 4He gas.

  5. Variation of the resonance width of HOCl(6{nu}{sub OH}) with total angular momentum: Comparison between {ital ab initio} theory and experiment

    SciTech Connect

    Skokov, S.; Bowman, J.M. [Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322 (United States)] [Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322 (United States)

    1999-05-01

    Complex L{sup 2} calculations of the variation of (very narrow) resonance widths of the 6{nu}{sub OH} state of HOCl with total angular momentum are reported, using a recently developed, accurate {ital ab initio} potential energy surface [S. Skokov, J. M. Bowman, and K. A. Peterson, J. Chem. Phys. {bold 109}, 2662 (1998)]. The calculations are carried out within the adiabatic rotation approximation for the overall rotation and a truncation/recoupling method for the vibrational states. Comparisons with recent double-resonance experiments of the Rizzo and Sinha groups are made. The variation of resonance width with {ital J} for {ital K}=0 is shown to be due to rotation-induced coupling of the 6{nu}{sub OH} state with a dense set of states with large excitation in the dissociative coordinate. {copyright} {ital 1999 American Institute of Physics.}

  6. Fission fragment angular distributions

    SciTech Connect

    Bond, P.D.

    1985-01-01

    Many recent papers have found that calculations with the standard angular distribution formula for fission fragments from compound nuclei do not reproduce the strong anisotropies observed in the decay of high spin systems. They conclude that a noncompound nuclear process must exist for some partial waves and postulate an ad-hoc angular distribution for this process in order to reproduce the strong anisotropies. It is the purpose of this contribtion to demonstrate that much of the data are, in fact, consistent with compound nucleus formation and to emphasize that the standard model is not a generally valid way to calculate fission fragment angular distributions from a compound nucleus.

  7. Fourier relationship between angular position and optical orbital angular momentum

    E-print Network

    Eric Yao; Sonja Franke-Arnold; Johannes Courtial; Stephen Barnett; Miles Padgett

    2006-06-15

    We demonstrate the Fourier relationship between angular position and angular momentum for a light mode. In particular we measure the distribution of orbital angular momentum states of light that has passed through an aperture and verify that the orbital angular momentum distribution is given by the complex Fourier-transform of the aperture function. We use spatial light modulators, configured as diffractive optical components, to define the initial orbital angular momentum state of the beam, set the defining aperture, and measure the angular momentum spread of the resulting beam. These measurements clearly confirm the Fourier relationship between angular momentum and angular position, even at light intensities corresponding to the single photon level.

  8. Clinical variants of idiopathic torsion dystonia.

    PubMed Central

    Fahn, S

    1989-01-01

    Some patients with dystonic movements and postures not known to be caused by environmental or degenerative disorders can be segregated from classical-appearing idiopathic torsion dystonia on the basis of distinctive clinical and pharmacologic features. Many of them should be considered within the family of dystonia, as clinical variants of idiopathic torsion dystonia, while others are better classified as being part of other families of dyskinesias. In the former group are paradoxical dystonia, myoclonic dystonia, diurnal dystonia, and dopa-responsive dystonia. The latter group consists of dystonic tics and the various entities comprising paroxysmal dystonia, namely kinesigenic, nonkinesigenic and hypnogenic dystonia. PMID:2666583

  9. Hadronic Electroweak Spin-Torsion Interactions

    E-print Network

    Luca Fabbri

    2012-10-04

    In a previous paper we considered the most general field equations for a system of two fermions of which one single-handed, showing that the spin-torsion interactions among these spinors had the same structure of the electroweak forces among leptons; in this paper we consider the most general field equations for a system of two fermions, showing that the spin-torsion interactions among these spinors have a structure similar to that of the electroweak forces among hadrons: possible differences are discussed, and consequently further extensions are speculated.

  10. The Flyby Anomaly and the Effect of a Topological Torsion Current

    E-print Network

    Pinheiro, Mario J

    2014-01-01

    A new variational technique determines the general condition of equilibrium of a rotating gravito-electromagnetic system and provides a modified dynamical equation of motion from where it emerges a so-far unforseen topological torsion current (TTC) [Mario J. Pinheiro (2013) 'A Variational Method in Out-of-Equilibrium Physical Systems', Scientific Reports {\\bf 3}, Article number: 3454]. We suggest that the TTC may explain, in a simple and direct way, the anomalous acceleration detected in spacecrafts during close planetary flybys. In addition, we theorize that TTC may represent an unforeseen relationship between linear momentum and angular motion through the agency of a vector potential.

  11. The flyby anomaly and the effect of a topological torsion current

    NASA Astrophysics Data System (ADS)

    Pinheiro, Mario J.

    2014-08-01

    A new variational technique determines the general condition of equilibrium of a rotating gravitational or electromagnetic system (or both) and provides a modified dynamical equation of motion from where it emerges a so-far unforseen topological torsion current (TTC) (Pinheiro, 2013) [63]. We suggest that the TTC may explain, in a simple and direct way, the anomalous acceleration detected in spacecrafts during close planetary flybys. In addition, we theorize that TTC may represent a novel relationship between linear momentum and angular motion through the agency of a vector potential.

  12. TWISTING COCHAINS AND HIGHER TORSION 091104 KIYOSHI IGUSA

    E-print Network

    Igusa, Kiyoshi

    " in higher Franz-Reidemeister (FR) torsion and higher analytic torsion. Briefly, any fiber bundle gives of a fiber bundle F E B whose base B and fiber F are finite cell complexes. It is given by the tensor Classification. Primary 57R22, Secondary 19J10, 55R40. Key words and phrases. higher Franz-Reidemeister torsion

  13. Optical Broadband Angular Selectivity

    E-print Network

    Shen, Yichen

    Light selection based purely on the angle of propagation is a long-standing scientific challenge. In angularly selective systems, however, the transmission of light usually also depends on the light frequency. We tailored ...

  14. Metamaterial broadband angular selectivity

    E-print Network

    Shen, Yichen

    We demonstrate how broadband angular selectivity can be achieved with stacks of one-dimensionally periodic photonic crystals, each consisting of alternating isotropic layers and effective anisotropic layers, where each ...

  15. Matter-antimatter asymmetry and dark matter from torsion

    SciTech Connect

    Poplawski, Nikodem J. [Department of Physics, Indiana University, Swain Hall West, 727 East Third Street, Bloomington, Indiana 47405 (United States)

    2011-04-15

    We propose a simple scenario which explains the observed matter-antimatter imbalance and the origin of dark matter in the Universe. We use the Einstein-Cartan-Sciama-Kibble theory of gravity which naturally extends general relativity to include the intrinsic spin of matter. Spacetime torsion produced by spin generates, in the classical Dirac equation, the Hehl-Datta term which is cubic in spinor fields. We show that under a charge-conjugation transformation this term changes sign relative to the mass term. A classical Dirac spinor and its charge conjugate therefore satisfy different field equations. Fermions in the presence of torsion have higher energy levels than antifermions, which leads to their decay asymmetry. Such a difference is significant only at extremely high densities that existed in the very early Universe. We propose that this difference caused a mechanism, according to which heavy fermions existing in such a Universe and carrying the baryon number decayed mostly to normal matter, whereas their antiparticles decayed mostly to hidden antimatter which forms dark matter. The conserved total baryon number of the Universe remained zero.

  16. Torsion of a Large Appendix Testis Misdiagnosed as Pyocele

    PubMed Central

    Meher, Susanta; Rath, Satyajit; Sharma, Rakesh; Sasmal, Prakash Kumar; Mishra, Tushar Subhadarshan

    2015-01-01

    Torsion of the appendix testis is not an uncommon cause of acute hemiscrotum. It is frequently misdiagnosed as acute epididymitis, orchitis, or torsion of testis. Though conservative management is the treatment of choice for this condition, prompt surgical intervention is warranted when testicular torsion is suspected. We report a case of torsion of a large appendix testis misdiagnosed as pyocele. Emergency exploration of it revealed a large appendix testis with torsion and early features of gangrene. After excision of the appendix testis, the wound was closed with an open drain. The patient had an uneventful and smooth postoperative recovery. PMID:25861514

  17. Complex angular momentum theory of state-to-state integral cross sections: resonance effects in the F + HD ? HF(v' = 3) + D reaction.

    PubMed

    Sokolovski, D; Akhmatskaya, E; Echeverría-Arrondo, C; De Fazio, D

    2015-07-01

    State-to-state reactive integral cross sections (ICSs) are often affected by quantum mechanical resonances, especially near a reactive threshold. An ICS is usually obtained by summing partial waves at a given value of energy. For this reason, the knowledge of pole positions and residues in the complex energy plane is not sufficient for a quantitative description of the patterns produced by resonance. Such description is available in terms of the poles of an S-matrix element in the complex plane of the total angular momentum. The approach was recently implemented in a computer code , available in the public domain [Comput. Phys. Commun., 2014, 185, 2127]. In this paper, we employ the package to analyse in detail, for the first time, the resonance patterns predicted for integral cross sections (ICSs) of the benchmark F + HD ? HF(v' = 3) + D reaction. The v = 0, j = 0, ? = 0 ? v' = 3, j' = 0, 1, 2, and ?' = 0, 1, 2 transitions are studied for collision energies from 58.54 to 197.54 meV. For these energies, we find several resonances, whose contributions to the ICS vary from symmetric and asymmetric Fano shapes to smooth sinusoidal Regge oscillations. Complex energies of metastable states and Regge pole positions and residues are found by Padé reconstruction of the scattering matrix elements. The accuracy of the code, relation between complex energies and Regge poles, various types of Regge trajectories, and the origin of the J-shifting approximation are also discussed. PMID:26112337

  18. Reliability of a MEMS torsional ratcheting actuator

    Microsoft Academic Search

    Danelle M. Tanner; Jeremy A. Walraven; Stephen M. Barnes; Norman F. Smith; Fernando Bitsie; Scot E. Swanson

    2001-01-01

    A new surface-micromachined actuator, the torsional ratcheting actuator (TRA), has been characterized and stress tested for reliability. The most prominent failure mechanism when running at high speeds (ratcheting frequencies of 333, 1000, or 3000 Hz) is wear on rubbing surfaces leading to adhesion between the ring gear and the alignment guide. We have also observed failure when running at low

  19. Fracture in Bending, Torsion and Radial Pressure

    Microsoft Academic Search

    C. Gurney

    1968-01-01

    I HAVE shown1 that glass rods with normally damaged surfaces, and subjected to sustained loading, fracture in equal times when subjected to numerically equal prior principal stresses, in bending, torsion and radial fluid pressure. The term prior stress refers to the stress distribution which exists before any cracking has occurred. I interpreted these results in terms of quasistatic crack growth

  20. Primary Omental Torsion: Two Case Reports

    Microsoft Academic Search

    Ibtisam Al-Bader; Ali Al-Said Ali; Khalid Al-Sharraf; Abdulla Behbehani

    2007-01-01

    Objective: To describe two cases of primary omental torsion as an uncommon cause of abdominal pain. Clinical Presentation and Intervention: Two female patients presented to our surgical service with right-sided abdominal pain. In view of their clinical presentation and workup, both patients required operative intervention. At laparotomy, the cause of the pain was recognized to be due to infarcted omentum

  1. Electron-photon angular correlation in atomic physics

    Microsoft Academic Search

    K. Blum; H. Kleinpoppen

    1979-01-01

    A review is given on recent developments of electron-photon angular correlations resulting from electron impact of atoms and molecules. After a description of experimental methods the theory of measurement of electron-photon angular correlations is outlined in the following way. By applying measurements of electron-photon angular correlations a sub-ensemble of excited atoms is selected from the atomic target which can be

  2. Angular Momentum Operator Identities G I. Orbital Angular Momentum

    E-print Network

    Simons, Jack

    Angular Momentum Operator Identities G I. Orbital Angular Momentum A particle moving with momentum p at a position r relative to some coordinate origin has so-called orbital angular momentum equal to L = r x p . The three components of this angular momentum vector in a cartesian coordinate system

  3. Sudden lateral asymmetry and torsional oscillations of section models of suspension bridges

    NASA Astrophysics Data System (ADS)

    Plaut, R. H.; Davis, F. M.

    2007-11-01

    Cable-supported bridges typically exhibit minimal torsional motion under traffic and wind loads. If symmetry of the bridge about the deck's centerline is suddenly lost, such as by the failure of one or more cables or hangers (suspenders), torsional motion of the deck may grow and angles of twist may become large. The initiation of the disastrous torsional oscillations of the original Tacoma Narrows Bridge involved a sudden lateral asymmetry due to loosening of a cable band at midspan. The effects of these types of events on two-degree-of-freedom and four-degree-of-freedom section models of suspension bridges are analyzed. Vertical and rotational motions of the deck, along with vertical motions of the cables, are considered. A harmonic vertical force and an aerodynamic moment proportional to angular velocity are applied to the deck. Resistance is provided by translational and rotational springs and dashpots. Flutter instability and large oscillations occur under the aerodynamic moment, which provides "negative damping." In order to model the occurrence of limit cycles, nonlinear damping of the van der Pol type is included in one case, and nonlinear stiffness of the hangers in others. The frequencies of the limit cycles are compared to the natural frequencies of the system.

  4. Design and analysis of a torsion braid pendulum displacement transducer

    NASA Technical Reports Server (NTRS)

    Rind, E.; Bryant, E. L.

    1981-01-01

    The dynamic properties at various temperatures of braids impregnated with polymer can be measured by using the braid as the suspension of a torsion pendulum. This report describes the electronic and mechanical design of a torsional braid pendulum displacement transducer which is an advance in the state of the art. The transducer uses a unique optical design consisting of refracting quartz windows used in conjunction with a differential photocell to produce a null signal. The release mechanism for initiating free torsional oscillation of the pendulum has also been improved. Analysis of the precision and accuracy of the transducer indicated that the maximum relative error in measuring torsional amplitude was approximately 0. A serious problem inherent in all instruments which use a torsional suspension was analyzed: misalignment of the physical and torsional axes of the torsional member which results in modulation of the amplitude of the free oscillation.

  5. Teleparallelism-A viable theory of gravity?

    Microsoft Academic Search

    Folkert Müller-Hoissen; Jürgen Nitsch

    1983-01-01

    The teleparallelism theory of gravity is presented as a constrained Poincaré gauge theory. Arguments are given in favor of a two-parameter family of field Lagrangians quadratic in torsion. The inclusion of a \\

  6. The Angular Momentum Dichotomy

    NASA Astrophysics Data System (ADS)

    Teklu, Adelheid; Remus, Rhea-Silvia; Dolag, Klaus; Burkert, Andreas

    2015-02-01

    In the context of the formation of spiral galaxies the evolution and distribution of the angular momentum of dark matter halos have been discussed for more than 20 years, especially the idea that the specific angular momentum of the halo can be estimated from the specific angular momentum of its disk (e.g. Fall & Efstathiou (1980), Fall (1983) and Mo et al. (1998)). We use a new set of hydrodynamic cosmological simulations called Magneticum Pathfinder which allow us to split the galaxies into spheroidal and disk galaxies via the circularity parameter ?, as commonly used (e.g. Scannapieco et al. (2008)). Here, we focus on the dimensionless spin parameter ? = J |E|1/2 / (G M5/2) (Peebles 1969, 1971), which is a measure of the rotation of the total halo and can be fitted by a lognormal distribution, e.g. Mo et al. (1998). The spin parameter allows one to compare the relative angular momentum of halos across different masses and different times. Fig. 1 reveals a dichotomy in the distribution of ? at all redshifts when the galaxies are split into spheroids (dashed) and disk galaxies (dash-dotted). The disk galaxies preferentially live in halos with slightly larger spin parameter compared to spheroidal galaxies. Thus, we see that the ? of the whole halo reflects the morphology of its central galaxy. For more details and a larger study of the angular momentum properties of disk and spheroidal galaxies, see Teklu et al. (in prep.).

  7. Fluidic angular velocity sensor

    NASA Technical Reports Server (NTRS)

    Berdahl, C. M. (inventor)

    1986-01-01

    A fluidic sensor providing a differential pressure signal proportional to the angular velocity of a rotary input is described. In one embodiment the sensor includes a fluid pump having an impeller coupled to a rotary input. A housing forming a constricting fluid flow chamber is connected to the fluid input of the pump. The housing is provided with a fluid flow restrictive input to the flow chamber and a port communicating with the interior of the flow chamber. The differential pressure signal measured across the flow restrictive input is relatively noise free and proportional to the square of the angular velocity of the impeller. In an alternative embodiment, the flow chamber has a generally cylindrical configuration and plates having flow restrictive apertures are disposed within the chamber downstream from the housing port. In this embodiment, the differential pressure signal is found to be approximately linear with the angular velocity of the impeller.

  8. Quasi-steady prediction of coupled bending-torsion flutter under rotating stall

    NASA Astrophysics Data System (ADS)

    Ananth, S. M.; Kushari, A.; Venkatesan, C.

    2013-11-01

    A method is presented in this paper to predict cascade flutter under subsonic stalled flow condition in a quasi-steady manner. The ability to predict the occurrence of aeroelastic flutter is highly important from the compressor design point of view. In the present work, the well known Moore-Greitzer compression system model is used to evaluate the flow under rotating stall and the linearized aerodynamic theory of Whitehead is used to estimate the blade loading. The cascade stability is then predicted by solving the structural model, which is posed as a complex eigenvalue problem. The possibility of occurrence of flutter in both bending and torsional modes is considered and the latter is found to be the dominant one, under subsonic stalled flow, for a large range of frequency ratios examined. It is also shown that the design of compressor blades at frequency ratios close to unity may result in rapid initiation of torsional flutter in the presence of stalled flow. A frequency ratio of 0.9 is primarily emphasized for most part of the study as many interesting features are revealed and the results are physically interpreted. Roughly a pitchfork pattern of energy distribution appears to occur between bending mode and torsional mode which ensures that only one flutter mode is possible at any instant in time. A bifurcation from bending flutter to torsional flutter is shown to occur during which the frequency of the two vibrating modes appear to coalesce for a very short period of time.

  9. Galactic dynamos and slow decay of magnetic fields from torsion modes of Lorentz violation

    NASA Astrophysics Data System (ADS)

    Garcia de Andrade, L. C.

    2011-01-01

    Campanelli et al. (2009) [9] have recently shown that electromagnetic fluctuations in Lorentz violation theories Colladay and Kostelecky (1998) [8] along differential rotation may induce galactic dynamo amplification of magnetic fields from primordial seeds. In this Letter, instead of using the Maxwell-Chern-Simmons-Lagrangian used in their paper, one adopts the Lagrangean of the type RFiFk, where R represent the torsion modes, without dynamical curvature. This so-called Minkowski-Cartan spacetime M4 torsion modes, allows us to handle QED vacuum in any Ricci scalar electrodynamics Lagrangean. It is shown that axial-torsion modes electrodynamics allows us to obtain a slow decay of magnetic fields. Thus primordial seed fields are amplified from differential rotation and protogalaxy turbulence as galactic dynamo action. This is mainly due to the fact that the collapse of the protogalaxy induces a strong suppression of the magnetic field decay. Magnetic field anisotropies are also considered. To resume, photon-torsion axial coupling in the quantum electrodynamics (QED) framework in Riemann flat contortioned spacetime may induce galactic dynamos. Fourier space transformation are used to compute electrodynamic equations.

  10. Effects of warping and pretwist on torsional vibration of rotating beams

    NASA Technical Reports Server (NTRS)

    Kaza, K. R. V.; Kielb, R. E.

    1984-01-01

    The effect of pretwist and warping on the torsional vibration of short-aspect-ratio rotating beams is examined for application to the modeling of turbofan, turboprop, and compressor blades. The equations of motion and the associated boundary conditions by using both Wagner's hypothesis and Washizu's theory are derived and a few minor limitations of the Wagner's hypothesis, as applied to thick blades, are pointed out and discussed. The equations for several special cases are solved in a closed form. Results are presented indicating the effect of warping, pretwist, and rotation on torsional vibration of beams as aspect ratio is varied. The results show that the structural warping and pretwist terms have a significant effect on torsional frequency and mode shapes of short-aspect-ratio blades whereas the inertial warping terms have negligible effect. Since the torsional frequencies and mode shapes are very important in aeroelastic analyses by using modal methods, the structural warping terms should be included in modeling turbofan, turboprop, compressor, and turbine blades.

  11. Monolithic 2-D scanning mirror using self-aligned angular vertical comb drives

    Microsoft Academic Search

    Jongbaeg Kim; Dane Christensen; Liwei Lin

    2005-01-01

    We have demonstrated microfabricated, monolithic two degrees of freedom (two-dimensional) electrostatic torsional mirrors using a three-mask process on silicon-on-insulator wafer with a single plastic deformation step. The mirror operated independently in two orthogonal directions as controlled by two sets of self-aligned angular vertical combs. The measured dynamic performance showed resonant frequencies of 10.56 and 1.54 kHz with optical scanning angles

  12. Angular shear plate

    DOEpatents

    Ruda, Mitchell C. (Tucson, AZ); Greynolds, Alan W. (Tucson, AZ); Stuhlinger, Tilman W. (Tucson, AZ)

    2009-07-14

    One or more disc-shaped angular shear plates each include a region thereon having a thickness that varies with a nonlinear function. For the case of two such shear plates, they are positioned in a facing relationship and rotated relative to each other. Light passing through the variable thickness regions in the angular plates is refracted. By properly timing the relative rotation of the plates and by the use of an appropriate polynomial function for the thickness of the shear plate, light passing therethrough can be focused at variable positions.

  13. Unveiling Angular Momentum

    NASA Astrophysics Data System (ADS)

    Robinson, Stephen

    2015-03-01

    Angular momentum is a notoriously difficult concept to grasp. Visualization often requires three-dimensional pictures of vectors pointing in seemingly arbitrary directions. A simple student-run laboratory experiment coupled with intuitive explanations by an instructor can clear up some of the inherent ambiguity of rotational motion. Specifically, the precessional period of a suspended spinning bicycle wheel can be related to the spinning frequency through a simple algebraic expression. An explanation of this precession apart from the concept of angular momentum will be given.

  14. Chern Simons formulation of three-dimensional gravity with torsion and nonmetricity

    NASA Astrophysics Data System (ADS)

    Cacciatori, Sergio L.; Caldarelli, Marco M.; Giacomini, Alex; Klemm, Dietmar; Mansi, Diego S.

    2006-12-01

    We consider various models of three-dimensional gravity with torsion or nonmetricity (metric affine gravity), and show that they can be written as Chern-Simons theories with suitable gauge groups. Using the groups ISO(2,1), SL(2,C) and SL(2,R)×SL(2,R), and the fact that they admit two independent coupling constants, we obtain the Mielke-Baekler model for zero, positive and negative effective cosmological constant respectively. Choosing SO(3,2) as the gauge group, one gets a generalization of conformal gravity that has zero torsion and only the trace part of the nonmetricity. This characterizes a Weyl structure. Finally, we present a new topological model of metric affine gravity in three dimensions arising from an SL(4,R) Chern-Simons theory.

  15. Angular distribution for electron excitation of the 4(2)S yields 4(2)P transition in Zn II - Comparison of experiment and theory

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Msezane, A. Z.; Henry, R. J. W.

    1983-01-01

    Differential electron-scattering cross sections for inelastic excitation of an ion have been measured for the first time. Experiments were carried out in a cross electron-ion beam geometry for the 4(2)S yields 4(2)P transition in Zn II at 75 eV. In addition, differential cross sections were calculated at energies between 15 and 100 eV in a five-state close-coupling approximation in which 4s, 4p, 3d(9)4s(2), 5s, and 4 d states were included. Agreement in shape between theory and experiment at 75 eV is excellent.

  16. On the physical interpretation of torsion-rotation parameters in methanol and acetaldehyde: Comparison of global fit and {ital ab initio} results

    SciTech Connect

    Xu, L. [Department of Physical Sciences, University of New Brunswick, Saint John, New Brunswick E2L 4L5 (Canada)] [Department of Physical Sciences, University of New Brunswick, Saint John, New Brunswick E2L 4L5 (Canada); Lees, R.M. [Department of Physics, University of New Brunswick, Fredericton, New Brunswick E3B 5A3 (Canada)] [Department of Physics, University of New Brunswick, Fredericton, New Brunswick E3B 5A3 (Canada); Hougen, J.T. [Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)] [Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

    1999-02-01

    Equilibrium structural constants and certain torsion{endash}rotation interaction parameters have been determined for methanol and acetaldehyde from {ital ab initio} calculations using GAUSSIAN 94. The substantial molecular flexing which occurs in going from the bottom to the top of the torsional potential barrier can be quantitatively related to coefficients of torsion{endash}rotation terms having a (1{minus}cos&hthinsp;3{gamma}) dependence on torsional angle {gamma}. The barrier height, six equilibrium structural constants characterizing the bottom of the potential well, and six torsion{endash}rotation constants are all compared to experimental parameters obtained from global fits to large microwave and far-infrared data sets for methanol and acetaldehyde. The rather encouraging agreement between the Gaussian and global fit results for methanol seems both to validate the accuracy of {ital ab initio} calculations of these parameters, and to demonstrate that the physical origin of these torsion{endash}rotation interaction terms in methanol lies primarily in structural relaxation with torsion. The less satisfactory agreement between theory and experiment for acetaldehyde requires further study. {copyright} {ital 1999 American Institute of Physics.}

  17. Metric-scalar gravity with torsion and the measurability of the non-minimal coupling

    E-print Network

    A. Accioly; H. Blas

    2006-08-29

    The "measurability" of the non-minimal coupling is discussed by considering the correction to the Newtonian static potential in the semi-classical approach. The coefficient of the "gravitational Darwin term" (GDT) gets redefined by the non-minimal torsion-scalar couplings. Based on a similar analysis of the GDT in the effective field theory approach to non-minimal scalar we conclude that for reasonable values of the couplings the correction is very small.

  18. Investigations of magnetic hysteresis of barium ferrite using the torsion pendulum method

    SciTech Connect

    Richter, H.J.; Hempel, K.A.

    1988-11-15

    The magnetic stiffness is measured by the torsion pendulum method as a function of the applied field. Measurements are performed on random assemblies of chemically coprecipitated barium ferrite powders. The magnetic stiffness for both minor and major loops of the hysteresis cycle is measured and compared with calculated curves based on the model of coherent rotation. The discrepancies between theory and experiment are partly due to the effect of magnetic interaction.

  19. Torsion and transverse bending of cantilever plates

    NASA Technical Reports Server (NTRS)

    Reissner, Eric; Stein, Manuel

    1951-01-01

    The problem of combined bending and torsion of cantilever plates of variable thickness, such as might be considered for solid thin high-speed airplane or missile wings, is considered in this paper. The deflections of the plate are assumed to vary linearly across the chord; minimization of the potential energy by means of the calculus of variations then leads to two ordinary linear differential equations for the bending deflections and the twist of the plate. Because the cantilever is analyzed as a plate rather than as a beam, the effect of constraint against axial warping in torsion is inherently included. The application of this method to specific problems involving static deflection, vibration, and buckling of cantilever plates is presented. In the static-deflection problems, taper and sweep are considered.

  20. Interfacing a torsion pendulum with a microcomputer

    SciTech Connect

    Bush, J.A.; Newby, J.W.

    1983-02-24

    Shear modulus testing is performed on the torsion pendulum at the General Electric Neutron Devices Department (GEND) as a means of gauging the state of cure for a polymer system. However, collection and reduction of the data to obtain the elastic modulus necessitated extensive operator involved measurements and calculations, which were subject to errors. To improve the reliability of the test, an analog-to-digital interface was designed and built to connect the torsion pendulum with a minicomputer. After the necessary programming was prepared, the system was tested and found to be an improvement over the old procedure in both quality and time of operation. An analysis of the data indicated that the computer generated modulus data were equivalent to the hand method data, but potential operator errors in frequency measurements and calculations were eliminated. The interfacing of the pendulum with the computer resulted in an overall time savings of 52 percent.

  1. Gravitational field around a screwed superconducting cosmic string in scalar-tensor theories

    NASA Astrophysics Data System (ADS)

    Bezerra, V. B.; Ferreira, C. N.

    2002-04-01

    We obtain the solution that corresponds to a screwed superconducting, bosonic cosmic string (SSCS) in the framework of a general scalar-tensor theory including torsion, using the weak field approximation. We investigate the metric of the SSCS in Brans-Dicke theory with torsion and analyze the case without torsion. We show that in the case with torsion the space-time background presents other properties different from those in which torsion is absent. When the spin vanishes, this torsion is a ? gradient and then it propagates outside of the string. We investigate the effect of torsion on the gravitational force and on the geodesics of a test particle moving around the SSCS. The accretion of matter by wakes formation when a SSCS moves with a speed v is investigated. We compare our results with those obtained for cosmic strings in the framework of scalar-tensor theory.

  2. UBIQUITOUS TORSIONAL MOTIONS IN TYPE II SPICULES

    SciTech Connect

    De Pontieu, B.; Hansteen, V. H. [Lockheed Martin Solar and Astrophysics Laboratory, Org. A021S, Building 252, 3251 Hanover Street, Palo Alto, CA 94304 (United States); Carlsson, M.; Rouppe van der Voort, L. H. M.; Rutten, R. J. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, N-0315 Oslo (Norway); Watanabe, H., E-mail: bdp@lmsal.com [Unit of Synergetic Studies for Space, Kyoto University, 17 Kitakazan Ohmine-cho, Yamashina, Kyoto 607-8471 (Japan)

    2012-06-10

    Spicules are long, thin, highly dynamic features that jut out ubiquitously from the solar limb. They dominate the interface between the chromosphere and corona and may provide significant mass and energy to the corona. We use high-quality observations with the Swedish 1 m Solar Telescope to establish that so-called type II spicules are characterized by the simultaneous action of three different types of motion: (1) field-aligned flows of order 50-100 km s{sup -1}, (2) swaying motions of order 15-20 km s{sup -1}, and (3) torsional motions of order 25-30 km s{sup -1}. The first two modes have been studied in detail before, but not the torsional motions. Our analysis of many near-limb and off-limb spectra and narrowband images using multiple spectral lines yields strong evidence that most, if not all, type II spicules undergo large torsional modulation and that these motions, like spicule swaying, represent Alfvenic waves propagating outward at several hundred km s{sup -1}. The combined action of the different motions explains the similar morphology of spicule bushes in the outer red and blue wings of chromospheric lines, and needs to be taken into account when interpreting Doppler motions to derive estimates for field-aligned flows in spicules and determining the Alfvenic wave energy in the solar atmosphere. Our results also suggest that large torsional motion is an ingredient in the production of type II spicules and that spicules play an important role in the transport of helicity through the solar atmosphere.

  3. Fluid driven torsional dipole seismic source

    SciTech Connect

    Hardee, Harry C. (Albuquerque, NM)

    1991-01-01

    A compressible fluid powered oscillating downhole seismic source device capable of periodically generating uncontaminated horizontally-propagated, shear waves is provided. A compressible fluid generated oscillation is created within the device which imparts an oscillation to a housing when the device is installed in a housing such as the cylinder off an existing downhole tool, thereby a torsional seismic source is established. Horizontal waves are transferred to the surrounding bore hole medium through downhole clamping.

  4. Comparisons Between Integral Equation Theory and Molecular Dynamics Simulations for Atomistic Models of Polyethylene Liquids

    SciTech Connect

    Curro, John G.; Webb III, Edmund B.; Grest, Gary S.; Weinhold, Jeffrey D.; Putz, Mathias; McCoy, John D.

    1999-07-21

    Molecular dynamics (MD) simulations were performed on dense liquids of polyethylene chains of 24 and 66 united atom CH{sub 2} units. A series of models was studied ranging in atomistic detail from coarse-grained, freely-jointed, tangent site chains to realistic, overlapping site models subjected to bond angle restrictions and torsional potentials. These same models were also treated with the self-consistent, polymer reference interaction site model (PRISM) theory. The intramolecular and total structure factors, as well as, the intermolecular radial distribution functions g(r) and direct correlation functions C(r) were obtained from theory and simulation. Angular correlation functions were also simulation obtained from the MD simulations. Comparisons between theory and reveal that PRISM theory works well for computing the intermolecular structure of coarse-grained chain models, but systematically underpredicts the extent of intermolecular packing as more atomistic details are introduced into the model. A consequence of g(r) having insufficient structure is that the theory yields an isothermal compressibility that progressively becomes larger, relative to the simulations, as overlapping the PRISM sites and angular restrictions are introduced into the model. We found that theory could be considerably improved by adding a tail function to C(r) beyond the effective hard core diameter. The range of this tail function was determined by requiring the theory to yield the correct compressibility.

  5. Angular analysis of the decay ? b ? ?(? N?) ? + ? -

    NASA Astrophysics Data System (ADS)

    Böer, Philipp; Feldmann, Thorsten; van Dyk, Danny

    2015-01-01

    We study the differential decay rate for the rare ? b ? ?(? N?) ? + ? - transition, including a determination of the complete angular distribution, assuming unpolarized ? b baryons. On the basis of a properly chosen parametrization of the various helicity amplitudes, we provide expressions for the angular observables within the Standard Model and a subset of new physics models with chirality-flipped operators. Hadronic effects at low recoil are estimated by combining information from lattice QCD with (improved) form-factor relations in Heavy Quark Effective Theory. Our estimates for large hadronic recoil — at this stage — are still rather uncertain because the baryonic input functions are not so well known, and non-factorizable spectator effects have not been worked out systematically so far. Still, our phenomenological analysis of decay asymmetries and angular observables for ? b ? ?(? N?) ? + ? - reveals that this decay mode can provide new and complementary constraints on the Wilson coefficients in radiative and semileptonic b ? s transitions compared to the corresponding mesonic modes.

  6. Torsional Rigidities of Weakly Strained DNAs

    PubMed Central

    Fujimoto, Bryant S.; Brewood, Gregory P.; Schurr, J. Michael

    2006-01-01

    Measurements on unstrained linear and weakly strained large (?340 bp) circular DNAs yield torsional rigidities in the range C = 170–230 fJ fm. However, larger values, in the range C = 270–420 fJ fm, are typically obtained from measurements on sufficiently small (?247 bp) circular DNAs, and values in the range C = 300–450 fJ fm are obtained from experiments on linear DNAs under tension. A new method is proposed to estimate torsional rigidities of weakly supercoiled circular DNAs. Monte Carlo simulations of the supercoiling free energies of solution DNAs, and also of the structures of surface-confined supercoiled plasmids, were performed using different trial values of C. The results are compared with experimental measurements of the twist energy parameter, ET, that governs the supercoiling free energy, and also with atomic force microscopy images of surface-confined plasmids. The results clearly demonstrate that C-values in the range 170–230 fJ fm are compatible with experimental observations, whereas values in the range C ? 269 fJ fm, are incompatible with those same measurements. These results strongly suggest that the secondary structure of DNA is altered by either sufficient coherent bending strain or sufficient tension so as to enhance its torsional rigidity. PMID:16963514

  7. Torsional oscillations of nonbare strange stars

    E-print Network

    Massimo Mannarelli; Giulia Pagliaroli; Alessandro Parisi; Luigi Pilo; Francesco Tonelli

    2015-04-28

    Strange stars are one of the possible compact stellar objects that can be formed after a supernova collapse. We consider a model of strange star having an inner core in the color-flavor locked phase surmounted by a crystalline color superconducting layer. These two phases constitute the {\\it quarksphere}, which we assume to be the largest and heaviest part of the strange star. The next layer consists of standard nuclear matter forming a ionic crust, hovering on the top of the quarksphere and prevented from falling by a strong dipolar electric field. The dipolar electric field arises because quark matter is confined in the quarksphere by the strong interaction, but electrons can leak outside forming a few hundreds Fermi thick electron layer separating the ionic crust from the underlying quark matter. The ionic matter and the crystalline color superconducting matter constitute two electromagnetically coupled crust layers. We study the torsional oscillations of these two layers. Remarkably, we find that if a fraction larger than $10^{-4}$ of the energy of a Vela-like glitch is conveyed to a torsional oscillation, the ionic crust will likely break. The reason is that the very rigid and heavy crystalline color superconducting crust layer will absorb only a small fraction of the glitch energy, leading to a large amplitude torsional oscillation of the ionic crust.

  8. Perinatal testicular torsion and medicolegal considerations.

    PubMed

    Massoni, F; Troili, G M; Pelosi, M; Ricci, S

    2014-06-01

    Perinatal testicular torsion (PTT) is a very complex condition because of rarity of presentation and diagnostic and therapeutic difficulties. In presence of perinatal testicular torsion, the involvement of contralateral testis can be present also in absence of other indications which suggest the bilateral involvement; therefore, occurrences supported by literature do not exclude the use of surgery to avoid the risk of omitted or delayed diagnosis. The data on possible recovery of these testicles are not satisfactory, and treatment consists of an observational approach ("wait-and-see") or an interventional approach. The hypothesis of randomized clinical trials seems impracticable because of rarity of disease. The authors present a case of PTT, analyzing injuries due to clinical and surgical management of these patients, according to medicolegal profile. The delayed diagnosis and the choice of an incorrect therapeutic approach can compromise the position of healthcare professionals, defective in terms of skill, prudence and diligence. Endocrine insufficiency is an unfortunate event. The analysis of literature seems to support, because of high risk, a surgical approach aimed not only at resolution of unilateral pathology or prevention of a relapse, but also at prevention of contralateral testicular torsion. PMID:24826979

  9. The effects of biasing torsional mutations in a conformational GA.

    PubMed

    Strizhev, Alex; Abrahamian, Edmond J; Choi, Sun; Leonard, Joseph M; Wolohan, Philippa R N; Clark, Robert D

    2006-01-01

    This paper describes the effects of incorporating torsional bias into a conformational Genetic Algorithm (GA) such as that found in the GASP program. Several major conclusions can be drawn. Biasing torsional angles toward values associated with local energy minima increases the rate of convergence of the fitness function (consisting of energy, steric, and pharmacophoric compatibility terms) for a set of molecules, but a definite tradeoff exists between total model energy and the steric and pharmacophoric compatibility terms in the fitness score. Biasing torsions in favor of sets of angles drawn from low-energy conformations does not guarantee low total energy, but biased torsional sampling does generally produce less strained models than does the uniform torsional sampling in classical GASP. Overall, torsionally biased sampling produces good models comprised of energetically favorable ligand conformations. PMID:16859317

  10. Lorentz Gauge Gravity and Induced Effective Theories

    E-print Network

    S. W. Kim; D. G. Pak

    2005-12-25

    We develop the gauge approach based on the Lorentz group to the gravity with torsion. With a Lagrangian quadratic in curvature we show that the Einstein-Hilbert action can be induced from a simple gauge model due to quantum corrections of torsion via formation of a gravito-magnetic condensate. An effective theory of cosmic knots at Planckian scale is proposed.

  11. A comparison of the torsional performance of stainless steel and titanium alloy tibial intramedullary nails: a clinically relevant approach.

    PubMed

    Aitchison, G A; Johnstone, A J; Shepherd, D E T; Watson, M A

    2004-01-01

    In recent years there has been a tendency to design and manufacture intramedullary nails from titanium alloy rather than from stainless steel. The aim of this project was to compare the torsional performance of one manufacturers standard stainless steel and titanium alloy tibial intramedullary nails, using their distal locking screw holes and dedicated cross screws to secure each nail distally. A custom built test rig and materials testing machine were used to determine the torsional rigidity of the nails. Theory was used to calculate the torsional rigidity of the central parts of each nail. From the mechanical testing, the mean torsional rigidity of the titanium alloy nail system was 40.9 N m2 while that of the stainless steel nail system was 34.6 N m2, for all distal interlocking screw positions tested. Based on theoretical calculations the torsional rigidity of the central part of the nail was 83 N m2 for the stainless steel nail and 66 N m2 for the titanium alloy nail. This study shows the importance of using the distal locking screw holes and dedicated cross screws to secure intramedullary nails during mechanical testing so that clinically relevant results are obtained about the whole nail system and not just the nail. PMID:15299235

  12. Minimum uncertainty states of angular momentum and angular position

    Microsoft Academic Search

    R. Zambrini; D. T. Pegg; S. M. Barnott; S. Franke-Arnold; M. Padgett

    2005-01-01

    In this paper, the much less known uncertainty relation for angular position and momentum to find the system at the edge of the phase interval is considered. States that minimize the uncertainty product with a constraint given either by the angular variance or by the angular momentum variance is examined.

  13. Angular momentum of the atmosphere Variations of atmospheric relative angular

    E-print Network

    O'Gorman, Paul

    Angular momentum of the atmosphere #12;Variations of atmospheric relative angular momentum OCW Schematic of dynamic angular momentum transports and surface torques #12;NCEP reanalysis imbalance -30 0 30 60 0.2 0.8 JJA DJF #12;Northward flux of momentum (m2s-2) Peixoto and Oort, Fig 11

  14. Angular Momentum Diagrams

    NASA Astrophysics Data System (ADS)

    Wormer, Paul E. S.; Paldus, Josef

    Starting from the simplest possible building blocks--a ket, a bra, a time-reversed ket, and a time-reversed bra--a diagrammatic formalism is developed for angular momentum coupling problems. The formalism comprises Clebsch-Gordan coefficients as well as 3jm-symbols. The idea of constructing invariants (internal lines) by contracting contragredient pairs of quantities is emphasized throughout. The Clebsch-Gordan series, and its extension to the coupling of more than two angular momenta, is introduced algebraically and diagrammatically. Recoupling between bases obtained in different coupling schemes is introduced and the connection between recoupling coefficients and irreducible 3nj-symbols is derived diagrammatically. The well-known diagrammatic rules due to Jucys and co-workers are derived by group theoretical means and simple rules for their practical exploitation are presented.

  15. Mangle: Angular Mask Software

    NASA Astrophysics Data System (ADS)

    Swanson, Molly; Tegmark, Max; Hamilton, Andrew; Hill, Colin

    2012-02-01

    Mangle is a suite of software designed to deal accurately and efficiently with complex angular masks, such as occur typically in galaxy surveys. Mangle performs the following tasks: converts masks between many handy formats (including HEALPix),rapidly finds the polygons containing a given point on the sphere,rapidly decomposes a set of polygons into disjoint parts,expands masks in spherical harmonics,generates random points with weights given by the mask, and implements computations for correlation function analysis.To mangle, a mask is an arbitrary union of arbitrarily weighted angular regions bounded by arbitrary numbers of edges. The restrictions on the mask are only (1) that each edge must be part of some circle on the sphere (but not necessarily a great circle), and (2) that the weight within each subregion of the mask must be constant. Mangle is complementary to and integrated with the HEALPix package; mangle works with vector graphics whereas HEALPix works with pixels.

  16. A mechanical comparison between conventional and modified angular plates for proximal humeral fractures.

    PubMed

    Carrera, Eduardo F; Nicolao, Fabio A; Netto, Nicola Archetti; Carvalho, Renato L; Dos Reis, Fernando B; Giordani, Enrico José

    2008-01-01

    The objective of this study is to present a modified angular blade plate for fixing 2-part and even 3-part fractures of the proximal humerus, as well as the results of the comparative mechanical test between the conventional angular blade plate and this new modified plate. The plates were tested in flexion and rotational trials in a wooden model that simulated a 2-part humeral fracture of the proximal extremity. The results (mean +/- SD) of bending strength and stiffness obtained after testing showed findings of 601 +/- 349 N and 0.5 +/- 0.2 N/mm, respectively, for the conventional plate and 4005 +/- 164 N and 3.9 +/- 0.7 N/mm, respectively, for the modified plate. The torsional stiffness test showed findings of 1.26 +/- 0.09 KN.mm degrees for the conventional plate and 1.74 +/- 0.21 KN.mm degrees for the modified plate. The test of torsional moment showed findings of 57.0 +/- 7.6 KN.mm for the conventional plate and 115.2 +/- 9.3 KN.mm for the modified plate. The test of angular displacement at the torsional moment showed findings of 50.8 degrees +/- 7.2 degrees for the conventional plate and 70.2 degrees +/- 2.6 degrees for the modified plate. The results of the mechanical trials of flexion and rotation were superior for the modified angular blade plate compared with the conventional angular blade plate. PMID:18359646

  17. Angular movement optical sensor

    NASA Astrophysics Data System (ADS)

    Palma-Vargas, Salvador; Sandoval-Romero, G. Eduardo; Ramírez-Ibarra, Angélica

    2006-09-01

    Most of the investigations that exist about the interferometer of Sagnac in our days, are made through fiber optic, which has the great advantage of having a big area size in very little space wound in a nucleus. The first interferometers of Sagnac, were used for very big angular speeds measures, it didn't have the advances to carry out detections of small signs, because the measurements systems like photo-detectors, amplifiers, filters, etc. didn't have the capacity of the systems that now exist. That is one reason that our experiments are based on the electronic advances, to make detections of phase changes of until less than 0.1 nm with area of 0.025 m2. Besides we proposed changes in the original interferometer diagram, adding some elements that can helps to achieve a bigger sensibility, accuracy and reduction of noise. Another of the advantages of use an interferometer of Sagnac, is work directly with the beams that travel through it, because we can observe the behavior from the optic road to external physical effects, like angular velocity or speed and little movements. Finally the acquisition devises and the software were used for calculate the angular frequency of the sensor directly from the experiment and know the parameters of the movement.

  18. The OD, D geometry of string theory

    NASA Astrophysics Data System (ADS)

    Berman, David S.; Blair, Chris D. A.; Malek, Emanuel; Perry, Malcolm J.

    2014-05-01

    We construct an action for double field theory using a metric connection that is compatible with both the generalised metric and the OD, D structure. The connection is simultaneously torsionful and flat. Using this connection, one may construct a proper covariant derivative for double field theory. We then write the doubled action in terms of the generalised torsion of this connection. This action then exactly reproduces that required for double field theory and gauged supergravity.

  19. Angular correlation studies of heavy-particle impact excitation of atoms

    Microsoft Academic Search

    K. Blum; H. Kleinpoppen

    1983-01-01

    A review is given of recent developments of angular correlation studies of heavy-particle impact excitation of atoms and molecules. After a brief discussion of the basic principles of experimental methods a theory of measurement of angular correlations from heavy-particle atom collisions is outlined in the following way. By applying angular correlation measurements a subensemble from the collision processes is selected

  20. Coherent Control of Angular Momentum Transfer in Resonant Two-Photon Light-Matter Interaction

    SciTech Connect

    Malik, D. A.; Kimel, A. V.; Kirilyuk, A.; Rasing, Th.; Zande, W. J. van der [Radboud University Nijmegen, Institute for Molecules and Materials, P.O. Box 9010, NL-6500 GL Nijmegen (Netherlands)

    2010-04-02

    We show experimentally and theoretically that a polarization-shaped femtosecond laser pulse with a zero net angular momentum creates a net angular momentum in atomic rubidium during resonant two-photon excitation. The necessary conditions for the creation of a nonzero angular momentum as well as the excitation efficiencies are analyzed in the framework of second-order time-dependent perturbation theory.

  1. Experimental-numerical investigation of the dynamic stability of flexural-torsional vibrations of compressor blades under conditions of attached and separated flow. Part 2. Cross aerodynamic characteristics

    Microsoft Academic Search

    A. L. Stel’makh; A. P. Zinkovskii; Ya. A. Stel’makh

    2009-01-01

    We consider the results of investigation of cross aerodynamic characteristics of compressor blades and their dynamic stability\\u000a under flexural-torsional vibrations for the cases of attached and separated flows in broad ranges of variations of the phase\\u000a shift, the ratio of amplitudes of the translational and angular components of displacements, the angle of attack, the reduced\\u000a frequency of vibrations, and the

  2. Torsional deformation of double helix in interaction and aggregation of DNA.

    PubMed

    Cherstvy, A G; Kornyshev, A A; Leikin, S

    2004-05-20

    We incorporate sequence-dependent twisting between adjacent base pairs and torsional elasticity of double helix into the theory of DNA-DNA interaction. The results show that pairing and counterion-induced-aggregation of nonhomologous DNA are accompanied by considerable torsional deformation. The deformation tunes negatively charged phosphate strands and positively charged grooves on opposing molecules to stay "in register", substantially reducing nonideality of the helical structure of DNA. Its cost, however, makes interaction between nonhomologous DNA less energetically favorable. In particular, interaction between double helical DNA may result in sequence homology recognition and selective pairing of homologous fragments containing more than 100-200 base pairs. We also find a weak, but potentially measurable, increase in the expected counterion concentration required for aggregation of nonhomologous DNA and slightly higher solubility of such DNA above the critical concentration. PMID:18950140

  3. The Torsional Spectrum of Doubly Deuterated Methanol CHD_2OH

    NASA Astrophysics Data System (ADS)

    Ndao, M.; Coudert, L. H.; Kwabia Tchana, F.; Barros, J.; Margulès, L.; Manceron, Laurent; Roy, P.

    2014-06-01

    Although the torsional spectrum of several isotopic species of methanol with a symmetrical CH_3 or CD_3 was analyzed some time ago, it is recently, and only for the monodeuterated species CH_2DOH, that such an analysis was extended to the case of an asymmetrical methyl group. In this talk, based on a Fourier transform high-resolution spectrum recorded in the 20 to 670 wn region, the first analysis of the torsional spectrum of doubly deuterated methanol CHD_2OH will be presented. The Q branch of many torsional subbands could be observed and their assignment was initiated using a theoretical torsion-rotation spectrum computed with an approach accounting for the torsion-rotation Coriolis coupling and for the dependence of the generalized inertia tensor on the angle of internal rotation. 46 torsional subbands were thus assigned. For 28 of them, their rotational structure could be assigned and fitted using an effective Hamiltonian expressed as a J(J+1) expansion; and for 2 of them microwave transitions within the lower torsional level could also be included in the analysis. In several cases these analysis revealed that the torsional levels are strongly perturbed. In the talk, the torsional parameters retrieved in the analysis of the torsional subband centers will be discussed. The results of the analysis of the rotational structure of the torsional subbands will be presented and we will also try to understand the nature of the perturbations. At last, preliminary results about the analysis of the microwave spectrum will be presented. El Hilali, Coudert, Konov, and Klee, J. Chem. Phys. 135 (2011) 194309 Lauvergnat, Coudert, Klee, and Smirnov, J. Mol. Spectrosc. 256 (2009) 204 Quade, Liu, Mukhopadhyay, and Su, J. Mol. Spectrosc. 192 (1998) 378 Pearson, Yu, and Drouin, J. Mol. Spectrosc. 280 (2012) 119

  4. Angular Momentum in Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Del Popolo, A.

    We study the ``angular momentum catastrophe" in the framework of interaction among baryons and dark matter through dynamical friction. By means of Del Popolo (2009) model we simulate 14 galaxies similar to those investigated by van den Bosch, Burkert and Swaters (2001), and calculate the distribution of their spin parameters and the angular momenta. Our model gives the angular momentum distribution which is in agreement with the van den Bosch et al. observations. Our result shows that the ``angular momentum catastrophe" can be naturally solved in a model that takes into account the baryonic physics and the exchange of energy and angular momentum between the baryonic clumps and dark matter through dynamical friction.

  5. Generalised models for torsional spine and fan magnetic reconnection

    Microsoft Academic Search

    D. I. Pontin; A. K. Al-Hachami; K. Galsgaard

    2011-01-01

    Context. Three-dimensional (3D) null points are present in abundance in the solar corona, and the same is likely to be true in other astrophysical environments. Recent results from solar observations and from simulations suggest that reconnection at such 3D nulls may play an important role in the coronal dynamics. Aims: The properties of the torsional spine and torsional fan modes

  6. Paratubal Cyst With Isolated Torsion of the Fallopian Tube

    Microsoft Academic Search

    Rachel Katherine Bloom; Salvatore Larusso

    2009-01-01

    Isolated fallopian tube torsion (IFTT) is a rare condition in which the fallopian tube torses without any ovarian involvement. This condition most often occurs in perimenarchal girls and usually presents with pain on the side of torsion. A patient in her teens presented with worsening pain. Sonographic evaluation revealed a midline cystic structure displacing the uterus. The cyst was originally

  7. RANKS OF ELLIPTIC CURVES WITH PRESCRIBED TORSION OVER NUMBER FIELDS

    E-print Network

    Dujella, Andrej

    RANKS OF ELLIPTIC CURVES WITH PRESCRIBED TORSION OVER NUMBER FIELDS JOHAN BOSMAN, PETER BRUIN, ANDREJ DUJELLA, AND FILIP NAJMAN Abstract. We study the structure of the Mordell­Weil group of elliptic of all elliptic curves over quadratic fields with torsion subgroup T is empty, or it contains curves

  8. TORSIONAL VIBRATION REDUCTION IN INTERNAL COMBUSTION ENGINES USING CENTRIFUGAL PENDULUMS

    Microsoft Academic Search

    Cheng-Tang Lee; Steven W. Shaw

    The goal of the present work is to investigate the performance of tautochronic centrifugal pendulum vibration absorbers (CPVA's) for reducing torsional vibration in internal combustion engines. A mathematical model is first built for the torsional dynamics of an in- line, four-stroke, four-cylinder engine, including the consideration of inertia effects of connecting rods and pistons, gas pressure inside the cylinder chambers,

  9. Torsional Vibration Assessment Using Induction Machine Electromagnetic Torque Estimation

    Microsoft Academic Search

    Shahin Hedayati Kia; Humberto Henao; GÉrard-AndrÉ Capolino

    2010-01-01

    Mechanical anomalies such as load troubles, great torque dynamic variations, and torsional oscillations result in the shaft fatigue of electrical machine and other mechanical parts such as bearings and gearboxes. Particularly, the torsional vibration may attain a significant level at resonant frequencies which damage or cause additional lifetime consumption of mechanical parts. In this way, this paper proposes a noninvasive

  10. Modeling Torsion of Blood Vessels in Surgical Simulation and Planning

    E-print Network

    Leow, Wee Kheng

    Modeling Torsion of Blood Vessels in Surgical Simulation and Planning Hao LI a,1 , Wee Kheng LEOW a hybrid approach for modeling torsion of blood vessels that undergo deformation and joining. The proposed model takes 3D mesh of the blood vessel as input. It first fits a generalized cylinder to extract

  11. MAXIMAL TORSION RADICALS IN #[M ] AND MINIMAL PRIME MIDEALS

    E-print Network

    Beachy, John

    MAXIMAL TORSION RADICALS IN #[M ] AND MINIMAL PRIME M­IDEALS John A. Beachy Department torsion radicals of R--Mod. In this paper conditions are given under which this result can be extended = AnnM (X) for some M­prime module RX. A subfunctor # of the identity on R--Mod is called a radical of R

  12. Long-range excitons in conjugated polymers with ring torsions

    E-print Network

    Harigaya, Kikuo

    Long-range excitons in conjugated polymers with ring torsions Kikuo Harigaya Physical Science) are investigated by the intermediate exciton formalism. Long-range excitons are characterized, and the long-range component of the oscillator strengths is calculated. We nd that ring torsions a ect the long-range excitons

  13. Torsional Behavior of Reinforced Concrete Beams Strengthened with FRP Composites

    Microsoft Academic Search

    Saravanan Panchacharam; Abdeldjelil Belarbi

    Fiber Reinforced Polymer (FRP) as an external reinforcement is used extensively to address the strength requirements related to flexure and shear in structural systems. But the strengthening of members subjected to torsion is yet to be explored. In this paper, the behavior and performance of reinforced concrete members strengthened with externally bonded Glass FRP (GFRP) sheets subjected to pure torsion

  14. Bavu et al. Torsional waves in a bowed string

    E-print Network

    New South Wales, University of

    Bavu et al. Torsional waves in a bowed string Eric Bavu, John Smith and Joe Wolfe 1 Music Acoustics Bowing a string with a non-zero radius exerts a torque, which excites torsional waves. In general, the motion of the bow-string contact depends on the sum of the transverse speed v of the string plus

  15. Colliding Wave Solutions in a Symmetric Non-metric Theory

    E-print Network

    Ozay Gurtug; Mustafa Halilsoy

    2008-09-22

    A method is given to generate the non-linear interaction (collision) of linearly polarized gravity coupled torsion waves in a non-metric theory. Explicit examples are given in which strong mutual focussing of gravitational waves containing impulsive and shock components coupled with torsion waves does not result in a curvature singularity. However, the collision of purely torsion waves displays a curvature singularity in the region of interaction.

  16. Torsion and noninertial effects on a nonrelativistic Dirac particle

    SciTech Connect

    Bakke, K., E-mail: kbakke@fisica.ufpb.br

    2014-07-15

    We investigate torsion and noninertial effects on a spin-1/2 quantum particle in the nonrelativistic limit of the Dirac equation. We consider the cosmic dislocation spacetime as a background and show that a rotating system of reference can be used out to distances which depend on the parameter related to the torsion of the defect. Therefore, we analyse torsion effects on the spectrum of energy of a nonrelativistic Dirac particle confined to a hard-wall potential in a Fermi–Walker reference frame. -- Highlights: •Torsion effects on a spin- 1/2 particle in a noninertial reference frame. •Fermi–Walker reference frame in the cosmic dislocation spacetime background. •Torsion and noninertial effects on the confinement to a hard-wall confining potential.

  17. Interaction of ultrasound and torsional oscillation in solid 4He

    NASA Astrophysics Data System (ADS)

    Iwasa, Izumi; Goodkind, John; Kojima, Harry

    2015-03-01

    A new cell for studying ultrasound (10 MHz) propagation and torsional oscillation (1013 Hz) in solid He-4 was constructed. Improvements were made in the design of the spacer for the quartz transducers and the diameter of the torsion rod containing helium fill hole to reduce the effects of the shear modulus of the solid He-4 sample on the torsional oscillator response. Sudden shifts in both the sound propagation velocity and attenuation are observed below 100 mK. The detailed response depends on the ultrasound excitation level and thermal history. Increase in torsional oscillator frequency is observed at nearly the same temperature as where the sound propagation property shifts occur. At temperatures below 50 mK, changes in the ultrasound excitation level induce changes in the torsional oscillator frequency. Interpretation of these results in terms of He-3 impurity being trapped on dislocation lines will be discussed. NSF Grant DMR-1005325.

  18. Krukenberg tumor: a rare cause of ovarian torsion.

    PubMed

    Sandhu, Sameer; Arafat, Omar; Patel, Harshad; Lall, Chandana

    2012-01-01

    Ovarian torsion is the fifth most common gynecological surgical emergency. Ovarian torsion is usually associated with a cyst or a tumor, which is typically benign. The most common is mature cystic teratoma. We report the case of a 43-year-old woman who came to the Emergency Department with rare acute presentation of bilateral Krukenberg tumors, due to unilateral ovarian torsion. In this case report, we highlight the specific computed tomography (CT) features of ovarian torsion and demonstrate the unique radiological findings on CT imaging. Metastasis to the ovary is not rare and 5 to 10% of all ovarian malignancies are metastatic. The stomach is the common primary site in most Krukenberg tumors (70%); an acute presentation of metastatic Krukenberg tumors with ovarian torsion is rare and not previously reported in radiology literature. PMID:22439130

  19. Krukenberg Tumor: A Rare Cause of Ovarian Torsion

    PubMed Central

    Sandhu, Sameer; Arafat, Omar; Patel, Harshad; Lall, Chandana

    2012-01-01

    Ovarian torsion is the fifth most common gynecological surgical emergency. Ovarian torsion is usually associated with a cyst or a tumor, which is typically benign. The most common is mature cystic teratoma. We report the case of a 43-year-old woman who came to the Emergency Department with rare acute presentation of bilateral Krukenberg tumors, due to unilateral ovarian torsion. In this case report, we highlight the specific computed tomography (CT) features of ovarian torsion and demonstrate the unique radiological findings on CT imaging. Metastasis to the ovary is not rare and 5 to 10% of all ovarian malignancies are metastatic. The stomach is the common primary site in most Krukenberg tumors (70%); an acute presentation of metastatic Krukenberg tumors with ovarian torsion is rare and not previously reported in radiology literature. PMID:22439130

  20. Uniaxial angular accelerometers

    NASA Astrophysics Data System (ADS)

    Seleznev, A. V.; Shvab, I. A.

    1985-05-01

    The basic mechanical components of an angular accelerometer are the sensor, the damper, and the transducer. Penumatic dampers are simplest in construction, but the viscosity of air is very low and, therefore, dampers with special purpose oils having a high temperature stability (synthetic silicon or organosilicon oils) are most widely used. The most common types of viscous dampers are lamellar with meshed opposed arrays of fixed and movable vanes in the dashpot, piston dampers regulated by an adjustable-length capillary tube, and dampers with paddle wheel in closed tank. Another type of damper is an impact-inertial one with large masses absorbing the rotational energy upon collision with the sensor. Conventional measuring elements are resistive, capacitive, electromagnetic, photoelectric, and penumatic or hydraulic. Novel types of angular accelerometers are based on inertia of gas jets, electron beams, and ion beams, the piezoelectric effect in p-n junctions of diode and transistors, the electrokinetic effect in fluids, and cryogenic suspension of the sensor.

  1. Angular velocity optical sensor

    NASA Astrophysics Data System (ADS)

    Palma-Vargas, Salvador; Sandoval-Romero, G. Eduardo; Ramírez-Ibarra, Angélica

    2006-02-01

    Most of the investigations that exist about the interferometer of Sagnac in our days, are made through fiber optic, which has the great advantage of having a big area size in very little space wound in a nucleus. The first interferometers of Sagnac, were used for very big angular speeds measures, it didn't have the advances to carry out detections of small signs, because the measurements systems like photo-detectors, amplifiers, filters, etc. didn't have the capacity of the systems that now exist. That is one reason that our experiments are based on the electronic advances, to make detections of phase changes of until less than 0.1 nm with area of 0.025 m2. Besides we proposed changes in the original interferometer diagram, adding some elements that can helps to achieve a bigger sensibility, accuracy and reduction of noise. Another of the advantages of use an interferometer of Sagnac, is work directly with the beams that travel through it, because we can observe the behavior from the optic road to external physical effects, like angular velocity or speed and little movements.

  2. Torsional ARC Effectively Expands the Visual Field in Hemianopia

    PubMed Central

    Satgunam, PremNandhini; Peli, Eli

    2012-01-01

    Purpose Exotropia in congenital homonymous hemianopia has been reported to provide field expansion that is more useful when accompanied with harmonios anomalous retinal correspondence (HARC). Torsional strabismus with HARC provides a similar functional advantage. In a subject with hemianopia demonstrating a field expansion consistent with torsion we documented torsional strabismus and torsional HARC. Methods Monocular visual fields under binocular fixation conditions were plotted using a custom dichoptic visual field perimeter (DVF). The DVF was also modified to measure perceived visual directions under dissociated and associated conditions across the central 50° diameter field. The field expansion and retinal correspondence of a subject with torsional strabismus (along with exotropia and right hypertropia) with congenital homonymous hemianopia was compared to that of another exotropic subject with acquired homonymous hemianopia without torsion and to a control subject with minimal phoria. Torsional rotations of the eyes were calculated from fundus photographs and perimetry. Results Torsional ARC documented in the subject with congenital homonymous hemianopia provided a functional binocular field expansion up to 18°. Normal retinal correspondence was mapped for the full 50° visual field in the control subject and for the seeing field of the acquired homonymous hemianopia subject, limiting the functional field expansion benefit. Conclusions Torsional strabismus with ARC, when occurring with homonymous hemianopia provides useful field expansion in the lower and upper fields. Dichoptic perimetry permits documentation of ocular alignment (lateral, vertical and torsional) and perceived visual direction under binocular and monocular viewing conditions. Evaluating patients with congenital or early strabismus for HARC is useful when considering surgical correction, particularly in the presence of congenital homonymous hemianopia. PMID:22885782

  3. Enhanced angular current intensity from Schottky emitters.

    PubMed

    Fujita, S; Wells, T R C; Ushio, W; Sato, H; El-Gomati, M M

    2010-09-01

    Even though the Schottky emitter is a high-brightness source of choice for electron beam systems, its angular current intensity is substantially lower than that of thermionic cathodes, rendering the emitter impractical for applications that require high beam current. In this study, two strategies were attempted to enhance its angular intensity, and their experimental results are reported. The first scheme is to employ a higher extraction field for increasing the brightness. However, the tip shape transformation was found to induce undesirably elevated emission from the facet edges at high fields. The second scheme exploits the fact that the angular intensity is proportional to the square of the electron gun focal length [Fujita, S. & Shimoyama, H. (2005) Theory of cathode trajectory characterization by canonical mapping transformation. J. Electron Microsc. 54, 331-343], which can be increased by scaling-up the emitter tip radius. A high angular current intensity (J(Omega) approximately 1.5 mA sr(-1)) was obtained from a scaled-up emitter. Preliminary performance tests were conducted on an electron probe-forming column by substituting the new emitter for the original tungsten filament gun. The beam current up to a few microamperes was achieved with submicron spatial resolution. PMID:20701659

  4. Experimental Evidence for Partonic Orbital Angular Momentum at RHIC

    SciTech Connect

    Fields, Douglas E. [University of New Mexico, Department of Physics and Astronomy, Albuquerque, NM 871331 (United States)

    2011-12-14

    Although one might naively anticipate that the proton, being the lowest baryonic energy state, would be in a L = 0 state, the current theoretical understanding is that it must carry orbital angular momentum in order, for example, to have a non-zero anomalous magnetic moment. I will review the experimental evidence linked theoretically to orbital angular momentum of the proton's constituents from the RHIC experiments and summarize by presenting a challenge to the theory community--to develop a consistent framework which can explain the spin polarization asymmetries seen at RHIC and elsewhere, and give insight to the partonic wave-functions including orbital angular momentum.

  5. Angular distributions in heavy-ion-induced fission

    Microsoft Academic Search

    B. B. Back; R. R. Betts; J. E. Gindler; B. D. Wilkins; S. Saini; M. B. Tsang; C. K. Gelbke; W. G. Lynch; M. A. McMahan; P. A. Baisden

    1985-01-01

    Fission fragment angular distributions have been measured in reactions of 16O+ 208Pb, 232Th, 238U, 248Cm; 19F+ 208Pb; 24Mg+ 208Pb; 28Si+ 208Pb; 32S+ 197Au; and 32S+ 208Pb at several bombarding energies. The data are analyzed within the standard theory and it is found that the angular anisotropies for reactions with 24Mg and heavier projectiles are significantly larger than expected theoretically. Comparative

  6. Differentially expressed DNA sequences following recovery from unilateral testicular torsion in rat

    Microsoft Academic Search

    Farag A. Ahmed; Anne M. Jequier; James M. Cummins; James Whelan

    2001-01-01

    The molecular response during recovery from torsion-induced stress in the testis is diverse with a variety of mechanisms. In this study, using unilateral testicular torsion in rat as a model, we used subtractive hybridisation to identify differentially expressed DNA sequences in the torsioned and control testes. Three genes were identified as being down regulated in the torsioned testis compared with

  7. Torsional changes in surgery for A-V phenomena.

    PubMed

    Sharma, P; Halder, M; Prakash, P

    1997-03-01

    The role of torsion in the aetiopathogenesis of A-V phenomena has not been sufficiently emphasized. The success of vertical displacement of horizontal recti in correction of A or V has not been attributed to torsional changes. To evaluate this aspect, 21 cases of A or V phenomena were subjected to monocular recession-resection procedure with vertical shifting. Preoperative and postoperative torsional changes were evaluated on synoptophore (subjective torsion), and confirmed by fundus photography (objective torsion). Intorsion with A phenomenon was seen preoperatively in 5 of 8 cases which increased after surgery and was seen postoperatively in the other 3 cases also. Extorsion was observed in 5 of 13 cases pre operatively in 'V' phenomenon, but the changes in extorsion after surgery were less dramatic than those in intorsion. The oblique overactions were reduced in cases where they were present. Correction of A-V phenomena by torsion induced by vertical shifting of horizontal recti muscles is proposed, highlighting the role of torsion in A-V phenomena. PMID:9475009

  8. Twisted anisotropic fibers for robust orbital-angular-momentum-based information transmission

    NASA Astrophysics Data System (ADS)

    Barshak, E. V.; Alexeyev, C. N.; Lapin, B. P.; Yavorsky, M. A.

    2015-03-01

    We study the light propagation in the twisted anisotropic optical fibers endowed with torsional mechanical stress by obtaining the analytical solution of the vector wave equation. We show that at certain interplay between fiber parameters optical vortex beams of topological charge ? =0 ,±1 ,±2 ,... become the modes of the fibers in question. To explain the splitting of the optical vortex propagation constants we introduce the notions of orbital birefringence and optical Zeeman effect. Moreover, we unveil that induced by torsional stress circular birefringence makes the vortex beams with the well-defined orbital angular momentum robust against small perturbations characterized by both constant and spatially varying orientation of a director. We believe that such fibers can be successfully utilized for the long-range robust transmission of information encoded in the light's orbital degrees of freedom.

  9. Minimum uncertainty states of angular momentum and angular position

    Microsoft Academic Search

    David T. Pegg; Stephen M. Barnett; Roberta Zambrini; Sonja Franke-Arnold; Miles Padgett

    2005-01-01

    The states of linear momentum that satisfy the equality in the Heisenberg uncertainty principle for position and momentum, that is the intelligent states, are also the states that minimize the uncertainty product for position and momentum. The corresponding uncertainty relation for angular momentum and angular position, however, is more complicated and the intelligent states need not be the constrained minimum

  10. Torsion constraints from cosmological magnetic field and QCD domain walls

    NASA Astrophysics Data System (ADS)

    Garcia de Andrade, L. C.

    2014-10-01

    Earlier Kostelecky [Phys. Rev. D 69, 105009 (2004)] has investigated the role of gravitational sector in Riemann-Cartan (RC) spacetime with torsion, in Lorentz and CPT violating (LV) Standard Model extension (SME). In his paper use of quantum electrodynamic (QED) extension in RC spacetime is made. More recently L. C. Garcia de Andrade [Phys. Lett. B 468, 28 (2011)] obtained magnetic field galactic dynamo seeds in the bosonic sector with massless photons, which proved to decay faster than necessary [Phys. Lett. B 711, 143 (2012)] to be able to seed galactic dynamos. In this paper it is shown that by using the fermionic sector of Kostelecky-Lagrangian and torsion written as a chiral current, one obtains torsion and magnetic fields explicitly from a Heisenberg-Ivanenko form of Dirac equation whose solution allows us to express torsion in terms of LV coefficients and magnetic field in terms of fermionic matter fields. When minimal coupling between electromagnetic and torsion fields is used it is shown that the fermionic sector of QED with torsion leads to resonantly amplify magnetic fields which mimics an ?2-dynamo mechanism. Fine-tuning of torsion is shown to result in the dynamo reversal, a phenomenon so important in solar physics and geophysics. Of course this is only an analogy since torsion is very weak in solar and geophysics contexts. An analogous expression for the ?-effect of mean-field dynamos is also obtained where the ?-effect is mimic by torsion. Similar resonant amplification mechanisms connected to early universe have been considered by Finelli and Gruppuso.

  11. Torsional suspension system for testing space structures

    NASA Technical Reports Server (NTRS)

    Reed, Wilmer H., III (inventor); Gold, Ronald R. (inventor)

    1991-01-01

    A low frequency torsional suspension system for testing a space structure uses a plurality of suspension stations attached to the space structure along the length thereof in order to suspend the space structure from an overhead support. Each suspension station includes a disk pivotally mounted to the overhead support, and two cables which have upper ends connected to the disk and lower ends connected to the space structure. The two cables define a parallelogram with the center of gravity of the space structure being vertically beneath the pivot axis of the disk. The vertical distance between the points of attachment of the cables to the disk and the pivot axis of the disk is adjusted to lower the frequency of the suspension system to a level which does not interfere with frequency levels of the space structure, thereby enabling accurate measurement.

  12. Torsion Tests of Stiffened Circular Cylinders

    NASA Technical Reports Server (NTRS)

    Moore, R L; Wescoat, C

    1944-01-01

    The design of curved sheet panels to resist shear involves a consideration of several factors: the buckling resistance of the sheet, the stress at which buckling becomes permanent, and the strength which may be developed beyond the buckling limit by tension-field action. Although some experimental as well as theoretical work has been done on the buckling and tension-field phases of this problem, neither of these types of action appears to be very well understood. The problem is of sufficient importance from the standpoint of aircraft design, it is believed, to warrant further experimental investigation. This report presents the results of the first series of torsion tests of stiffened circular cylinders to be completed in connection with this study at Aluminum Research Laboratories. (author)

  13. Plant-based torsional actuator with memory

    NASA Astrophysics Data System (ADS)

    Plaza, Nayomi; Zelinka, Samuel L.; Stone, Don S.; Jakes, Joseph E.

    2013-07-01

    A bundle of a few loblolly pine (Pinus taeda) cells are moisture-activated torsional actuators that twist multiple revolutions per cm length in direct proportion to moisture content. The bundles generate 10 N m kg-1 specific torque during both twisting and untwisting, which is higher than an electric motor. Additionally, the bundles exhibit a moisture-activated, shape memory twist effect. Over 70% of the twist in a wetted bundle can be locked-in by drying under constraint and then released by rewetting the bundle. Our results indicate that hemicelluloses dominate the shape fixity mechanism and lignin is primarily responsible for remembering the bundle’s original form. The bundles demonstrate proof of a high specific torque actuator with large angles of rotation and shape memory twist capabilities that can be used in microactuators, sensors, and energy harvesters.

  14. Axisymmetric flow within a torsionally oscillating sphere

    NASA Astrophysics Data System (ADS)

    Colombini, Marco

    2014-02-01

    The flow of an incompressible Newtonian fluid inside a torsionally oscillating spherical cavity is considered. The three-dimensional Navier-Stokes and continuity equations are solved by means of a Galerkin projection spectral method, based on a second-order incremental fractional-step approach. Legendre and Jacobi polynomial expansions are used in the zenithal and radial directions, respectively. Axisymmetric solutions are sought for a relatively wide set of the parameters controlling the flow, namely, the Rossby and the Womersley numbers. In particular, the behaviour of the flow for relatively large amplitudes of oscillation is studied, with emphasis on the generation of centrifugal instabilities. Numerical results are compared with experimental observations and semi-analytical solutions in the small-amplitude regime, showing good agreement.

  15. Experimental Study of Torsional Column Failure

    NASA Technical Reports Server (NTRS)

    Nile, Alfred S

    1939-01-01

    Thirty-three 24ST aluminum-alloy 2- by 2- by 0.10-inch channels, with lengths ranging from 10 to 90 inches were tested at Stanford University in compression to obtain an experimental verification of the theoretical formulas for torsional failure developed by Eugene E. Lundquist of the N.A.C.A. The observed critical loads and twist-axis locations were sufficiently close to the values obtained from the formulas to establish the substantial validity of the latter. The differences between observed and computed results were small enough to be accounted for by small and mostly unavoidable differences between actual test conditions and those assumed in deriving the formulas. Some data were obtained from the shorter specimens regarding the growth of the buckles that resulted in local buckling failure.

  16. Torsion of Space-time in f(R) gravity

    E-print Network

    Majid Mohsenzadeh; Ebrahim Yusofi

    2012-07-07

    In this paper, we first review some aspects of the f(R) gravity and then the concept of torsion of space-time due to metric-affine formalism in f(R) gravity is studied. Within this formalism in which the matter action is supposed to dependent on the connection, we achieve to interesting cases including non-zero torsion tensor. Then with the physical interpretation of torsion of space-time in high energy limit, the modified expression of Mach's principle in a very strong gravitational region is obtained.

  17. Torsion of a wandering spleen: an unusual abdominal catastrophe.

    PubMed

    Riaz ul Haq, Muhammad; Elhassan, Elbagir; Mahdi, Diaa

    2014-11-01

    Wandering spleen is a rare clinical entity characterised by splenic hypermobility resulting from laxity or maldevelopment of the suspensory gastrosplenic, splenorenal, and phrenicocolic ligaments. Diagnosis is quite difficult, especially in children because of the lack of symptoms and signs until splenic torsion have occurred. An array of investigations is possible but US with color Doppler, CT with intravenous contrast and MRI are frequently being used to diagnose wandering spleen with or without torsion. We present a case of 5 years old child with torsion of wandering spleen to highlight the importance of prompt diagnosis and management. PMID:25518790

  18. Fission-fragment angular distributions

    SciTech Connect

    Bond, P.D.

    1984-02-06

    The universally used ''exact'' formula for fission-fragment angular distributions is shown to be valid only under restrictive assumptions. The more general expression, which depends crucially on the final fragment spin distributions, predicts dramatically more anisotropic angular distributions for fission from nuclei at high spin. Recent ''anomalous'' results are analyzed.

  19. Fission-Fragment Angular Distributions

    NASA Astrophysics Data System (ADS)

    Bond, P. D.

    1984-02-01

    The universally used "exact" formula for fission-fragment angular distributions is shown to be valid only under restrictive assumptions. The more general expression, which depends crucially on the final fragment spin distributions, predicts dramatically more anisotropic angular distributions for fission from nuclei at high spin. Recent "anomalous" results are analyzed.

  20. The Angular Gyrus

    PubMed Central

    2013-01-01

    There is considerable interest in the structural and functional properties of the angular gyrus (AG). Located in the posterior part of the inferior parietal lobule, the AG has been shown in numerous meta-analysis reviews to be consistently activated in a variety of tasks. This review discusses the involvement of the AG in semantic processing, word reading and comprehension, number processing, default mode network, memory retrieval, attention and spatial cognition, reasoning, and social cognition. This large functional neuroimaging literature depicts a major role for the AG in processing concepts rather than percepts when interfacing perception-to-recognition-to-action. More specifically, the AG emerges as a cross-modal hub where converging multisensory information is combined and integrated to comprehend and give sense to events, manipulate mental representations, solve familiar problems, and reorient attention to relevant information. In addition, this review discusses recent findings that point to the existence of multiple subdivisions in the AG. This spatial parcellation can serve as a framework for reporting AG activations with greater definition. This review also acknowledges that the role of the AG cannot comprehensibly be identified in isolation but needs to be understood in parallel with the influence from other regions. Several interesting questions that warrant further investigations are finally emphasized. PMID:22547530

  1. Energy conditions in f( T) gravity with non-minimal torsion-matter coupling

    NASA Astrophysics Data System (ADS)

    Zubair, M.; Waheed, Saira

    2015-02-01

    The present paper examines the validity of energy bounds in a modified theory of gravity involving non-minimal coupling of torsion scalar and perfect fluid matter. In this respect, we formulate the general inequalities of energy conditions by assuming the flat FRW universe. For the application of these bounds, we particularly focus on two specific models that are recently proposed in literature and also choose the power law cosmology. We find the feasible constraints on the involved free parameters and evaluate their possible ranges graphically for the consistency of these energy bounds.

  2. ANALYTIC TORSIONS ON CONTACT MANIFOLDS MICHEL RUMIN AND NEIL SESHADRI

    E-print Network

    Rumin, Michel

    ANALYTIC TORSIONS ON CONTACT MANIFOLDS MICHEL RUMIN AND NEIL SESHADRI Abstract. We propose a de#28 Government (MEXT) Scholarship for research students. 1 #12; 2 MICHEL RUMIN AND NEIL SESHADRI in `middle

  3. TWISTED REIDEMEISTER TORSION, THE THURSTON NORM AND FIBERED MANIFOLDS

    E-print Network

    Friedl, Stefan

    polynomials of Lin [Li01] and Wada [Wa94]. See [Ki96] and [FV10] for details. Given f(t) = artr + ar+1tr+1 words and phrases. twisted Alexander polynomial, twisted Reidemeister torsion, Wada's invariant

  4. Constraints on background torsion from birefringence of CMB polarization

    E-print Network

    Moumita Das; Subhendra Mohanty; A. R. Prasanna

    2009-08-05

    We show that a non-minimal coupling of electromagnetism with background torsion can produce birefringence of the electromagnetic waves. This birefringence gives rise to a B-mode polarization of the CMB. From the bounds on B-mode from WMAP and BOOMERanG data, one can put limits on the background torsion at $\\xi_{1}T_{1}=(-3.35 \\pm 2.65) \\times 10^{-22} GeV^{-1}$.

  5. Torsional Coupling in Sliding Base-Isolated Structures

    Microsoft Academic Search

    Satish Nagarajaiah; Andrei M. Reinhorn; Michalakis C. Constantinou

    1993-01-01

    The lateral-torsional response of base-isolated structures, with sliding isolation system due to bidirectional lateral ground motion, is studied. The objective of the study is to identify the key system parameters that lead to significant torsional coupling in sliding base-isolated structures. The analysis procedure adopted can capture the highly nonlinear behavior of sliding systems in plane motion. The nonlinear biaxial stick-slip

  6. Cosmic Magnetic Fields from Torsion Modes and Massive Photon Inflation

    NASA Astrophysics Data System (ADS)

    Garcia de Andrade, L. C.

    2014-09-01

    Earlier Barrow & Tsagas (2008) showed that a slower decay of magnetic fields are present in open Friedmann universes, with traditional Maxwell equations. In their paper magnetic fields of the order of B˜10-33 G which are far below the value required to seed galactic dynamos were obtained. In this paper galactic dynamo seeds of the order of B˜10-23 G are obtained from massive electrodynamics in Einstein-Cartan-Proca (ECP) expanding universe of de Sitter type. Slow decay of magnetic fields in photon-torsion coupling in QED (Garcia de Andrade 2011b) have been recently shown by Garcia de Andrade (2012) also not be able to seed galactic dynamos. Torsion modes are constrained by the field equations. Space-time torsion is shown to be explicitly responsible for the slow decay of cosmic magnetic field. In the absence of massive photon torsion coupling the magnetic field decay is of the order B˜t-3/2, while when torsion is turn on B˜t-1.2. The pure massive-photon-torsion contribution amplifies the magnetic field by Btorsion˜t0.1 which characterizes an extremely slow magnetic dynamo action due to purely torsion gravitational effects. Recently, Barrow et al. (2012) have obtained superadiabatic amplification of B-fields in the Friedmann open cosmology which lies within 10-20 G and 10-12 G which falls very comfortable within limits to seed galactic dynamos. Other simple solutions where B-field decays as B˜a-1, relatively weak photon-torsion coupling approximation. These solutions are obtained for the de Sitter and Friedmann metrics.

  7. Comb-Actuated Resonant Torsional Microscanner With Mechanical Amplification

    Microsoft Academic Search

    Aslihan Arslan; Dean Brown; Wyatt O. Davis; Sven Holmstrom; Sertan Kutal Gokce; Hakan Urey

    2010-01-01

    A comb-actuated torsional microscanner is developed for high-resolution laser-scanning display systems. Typical torsional comb-drive scanners have fingers placed around the perimeter of the scanning mirror. In contrast, the structure in this paper uses cascaded frames, where the comb fingers are placed on an outer drive frame, and the motion is transferred to the inner mirror frame with a mechanical gain.

  8. The variation of torsion with vergence and elevation.

    PubMed

    Porrill, J; Ivins, J P; Frisby, J P

    1999-11-01

    Two recently developed kinematic models of human eye movements predict systematic departures from Listing's law which are associated with changes in vergence. This vergence-dependent torsion t is proportional to elevation e and vergence v, that is t = kev/2. The proposed value for k is either 1 (Van Rijn, L. J., & Van den Berg, A. V. (1993). Vision Research, 33, 691-708) or 1/2 (Minken, A. W. H., Gielen, C. C. A. M., & Van Gisbergen, J. A. M. (1995). Vision Research, 35, 93-102). One implication of both models is that an eye with a constant fixation direction should exhibit systematic torsional variation during movements of the other eye. This paper therefore examines the torsion produced by moving a fixation target inwards and outwards along the line-of-sight of the right eye at five different viewing elevations (0, +/- 15 and +/- 30 degrees). In a monocular analysis, each eye generally showed intorsion during convergence at positive elevation angles, whereas extorsion occurred at negative elevations; the opposite was true during divergence. However, the torsion response was visibly different between the five subjects, and depended on the direction of target motion. In a binocular analysis, cycloversion (mean of left and right eye torsion) varied dramatically both between subjects and between convergence and divergence; however, cyclovergence (torsional difference) was much less variable. Least-squares methods were used to estimate the constant k from monocular torsion, yielding values between 0.2 and 1.0; however, corresponding estimates based on cyclovergence were all close to 1/2. These findings support suggestions that a binocular control system couples the three-dimensional movements of the eyes, and that an existing model of monocular torsion should be generalised to the binocular case. PMID:10748926

  9. Differential equations of motion for combined flapwise bending, chordwise bending, and torsion of twisted nonuniform rotor blades

    NASA Technical Reports Server (NTRS)

    Houbolt, John C; Brooks, George W

    1957-01-01

    The differential equations of motion for the lateral and torsional deformations of twisted rotating beams are developed for application to helicopter rotor and propeller blades. No assumption is made regarding the coincidence of the neutral, elastic, and mass axes, and the generality is such that previous theories involving various simplifications are contained as subcases to the theory developed and presented in this paper. Special attention is given to coupling terms not found in previous theories, and methods of solution of the equations of motion are indicated by selected examples.

  10. Differential equations of motion for combined flapwise bending, chordwise bending, and torsion of twisted nonuniform rotor blades

    NASA Technical Reports Server (NTRS)

    Houbolt, John C; Brooks, George W

    1958-01-01

    The differential equations of motion for the lateral and torsional deformations of twisted rotating beams are developed for application to helicopter rotor and propeller blades. No assumption is made regarding the coincidence of the neutral, elastic, and mass axes, and the generality is such that previous theories involving various simplifications are contained as subcases to the theory presented in this paper. Special attention is given the terms which are not included in previous theories. These terms are largely coupling-type terms associated with the centrifugal forces. Methods of solution of the equations of motion are indicated by selected examples.

  11. Angular momentum & spin January 8, 2002

    E-print Network

    Landstreet, John D.

    Angular momentum & spin January 8, 2002 1 Angular momentum Angular momentum appears as a very properties of this quantity. 1.1 Definitions The classical definition of the angular momentum of a particle¯h, the quantum mechanical operator for angular momentum becomes L = -i¯h(r × ), for example Lz = -i¯h(x y - y x

  12. Smoothed dissipative particle dynamics with angular momentum conservation

    NASA Astrophysics Data System (ADS)

    Müller, Kathrin; Fedosov, Dmitry A.; Gompper, Gerhard

    2015-01-01

    Smoothed dissipative particle dynamics (SDPD) combines two popular mesoscopic techniques, the smoothed particle hydrodynamics and dissipative particle dynamics (DPD) methods, and can be considered as an improved dissipative particle dynamics approach. Despite several advantages of the SDPD method over the conventional DPD model, the original formulation of SDPD by Español and Revenga (2003) [9], lacks angular momentum conservation, leading to unphysical results for problems where the conservation of angular momentum is essential. To overcome this limitation, we extend the SDPD method by introducing a particle spin variable such that local and global angular momentum conservation is restored. The new SDPD formulation (SDPD+a) is directly derived from the Navier-Stokes equation for fluids with spin, while thermal fluctuations are incorporated similarly to the DPD method. We test the new SDPD method and demonstrate that it properly reproduces fluid transport coefficients. Also, SDPD with angular momentum conservation is validated using two problems: (i) the Taylor-Couette flow with two immiscible fluids and (ii) a tank-treading vesicle in shear flow with a viscosity contrast between inner and outer fluids. For both problems, the new SDPD method leads to simulation predictions in agreement with the corresponding analytical theories, while the original SDPD method fails to capture properly physical characteristics of the systems due to violation of angular momentum conservation. In conclusion, the extended SDPD method with angular momentum conservation provides a new approach to tackle fluid problems such as multiphase flows and vesicle/cell suspensions, where the conservation of angular momentum is essential.

  13. Coherent Control of Molecular Torsion and the Active-space Decomposition Method

    NASA Astrophysics Data System (ADS)

    Parker, Shane Matthew

    This dissertation discusses schemes and applications for the strong-field control of molecular torsions as well as introduces the active-space decomposition method. In the first part, a route to realize general control over the torsional motions of a class of biaryl compounds is proposed. Torsion in biaryl compounds--molecules with two aromatic moieties connected by a bond about which the barrier to rotation is small--mediates the electronic coupling between the two rings in the molecule. Thus, by controlling the torsion angle, one also controls the electron transfer and transport rates, the absorption and emission spectra, and the molecule's chirality. In our scheme, a non-resonant half-cycle pulse interacts with the permanent dipole of only one moiety of the pre-oriented biaryl compound. In the non-adiabatic regime, coherent motion is initiated by the half-cycle pulse. In the adiabatic regime, the torsion angle is tuned by the pulse. By properly choosing the parameters and polarization of the half-cycle pulse, we show that free internal rotation can be started or that the molecular chirality can be inverted. Then, with the aid of optimal control theory, we design "deracemizing" control pulses, i.e., control pulses that convert a racemic mixture into an enantiopure mixture. Finally, we explore the potential for this type of control in a single-molecule pulling experiment. In the second part, we describe the active space decomposition method for computing excited states of molecular dimers. In this method, the dimer's wavefunction is expressed as a linear combination of direct products of orthogonal localized monomer states. The adiabatic dimer states are found by diagonalizing the Hamiltonian in this direct product space. Matrix elements between direct product states are computed directly, without ever explicitly forming the dimer wavefunction, thus enabling calculations of dimers with active space sizes that would be otherwise impossible. The decomposed wavefunctions approach the exact dimer wavefunctions in two limiting cases: when there is no coupling between the two monomers and when a full set of monomer states is used. After introducing the method, we apply it to the computation of model Hamiltonians for the singlet fission process.

  14. Angular Momentum Balance Tuesday, January 7, 2014

    E-print Network

    Bordoni, Simona

    Angular Momentum Balance and Winds Tuesday, January 7, 2014 #12;(Source: CLAUS, http Extratropical macroturbulence transports angular momentum into regions of wave generation !"#$%&'( )*+,( )*+-( Tuesday, January 7, 2014 #12;Eddy angular momentum transport (ERA-40 Atlas, http

  15. Relaxation of rotational angular momentum of polar diatomic molecules in simple liquids

    SciTech Connect

    Padilla, A.; Perez, J. [Departamento de Fisica Fundamental y Experimental, Electronica y Sistemas, Universidad de La Laguna, 38204 Tenerife (Spain)

    2007-03-15

    The relaxation processes of rotational angular momentum of polar diatomic molecules diluted in simple liquids are analyzed by applying a non-Markovian relaxation theory to the study of the binary time autocorrelation function of the angular momentum. This non-Markovian theory was previously applied to the study of the infrared and Raman spectroscopy, and also to the analysis of the rotational energy relaxation processes. We have obtained non-Markovian evolution equations for the two-time j-level angular momentum correlation components involved in the angular momentum correlation function. In these equations, the time-dependent angular momentum transfer rates and the pure orientational angular transfer rates are given in terms of the binary time autocorrelation function of the diatomic-solvent anisotropic interaction. The non-Markovian evolution equations converge to Markovian ones in the long time limit, reaching the angular momentum transfer rates in the usual time-independent form. Alternative time scales for the angular relaxation processes, relative to the individual rotational processes as well as to the global decay correlations, are introduced and analyzed. The theory is applied to the study of the angular momentum relaxation processes of HCl diluted in liquid SF{sub 6}, a system for which rotational energy relaxation and infrared and Raman spectroscopy was previously analyzed in the scope of the same theory.

  16. Angular correlations of galaxy distribution

    E-print Network

    M. Montuori; F. Sylos-Labini

    1997-06-30

    We study the angular correlations of various galaxy catalogs (CfA1, SSRS1, Perseus-Pisces, APM Bright Galaxies and Zwicky). We find that the angular correlation exponent is $\\gamma_a= 0.1 \\pm 0.1$ rather than $\\gamma_a=0.7$ as usually found by the standard correlation function $\\omega(\\theta)$. We identify the problem in the artificial decay of $\\omega(\\theta)$. Moreover we find that no characteristic angular scale is present in any of the analyzed catalogs. Finally we show that all the available data are consistent with each other and the angular distribution of galaxies is quite naturally compatible with a fractal structure with $D \\approx 2$.

  17. Plasmons with orbital angular momentum

    SciTech Connect

    Mendonca, J. T. [IPFN, Instituto Superior Tecnico, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal); Ali, S. [IPFN, Instituto Superior Tecnico, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal); National Centre for Physics, Shahdra Valley Road, Islamabad 44000 (Pakistan); Thide, B. [Swedish Institute of Space Physics, Angstroem Laboratory, P.O. Box 537, SE-751 21 Uppsala (Sweden)

    2009-11-15

    Electron plasma waves carrying orbital angular momentum are investigated in an unmagnetized collisionless plasma composed of inertial electrons and static ions. For this purpose, the usual plasmon dispersion relation is employed to derive an approximate paraxial equation. The latter is analyzed with a Gaussian beam solution. For a finite angular momentum associated with the plasmon, Laguerre-Gaussian (LG) solutions are employed for solving the electrostatic potential problem which gives approximate solution and is valid for plasmon beams in the paraxial approximation. The LG potential determines the electric field components and energy flux of plasmons with finite angular momentum. Numerical illustrations show that the radial and angular mode numbers strongly modify the profiles of the LG potential.

  18. Torsional vibration reduction using passive nonlinear absorbers

    NASA Astrophysics Data System (ADS)

    Shaw, Steven W.; Alsuwaiyan, Abdallah

    2000-04-01

    This paper considers the dynamic performance of systems of centrifugal pendulum vibration absorbers that are used to attenuate torsional vibrations in rotating systems. These absorbers, which can be found in certain IC engines and helicopter rotors, consist of movable masses whose centers of mass are kinematically restricted to move along prescribed paths relative to the rotor of interest. The most common choice for absorber paths are simple circles that are slightly mistuned from the desired order, so that undesirable nonlinear behaviors are avoided when the absorbers undergo large amplitude motions. In this work we consider a range of different path types and tunings, with the goal of optimizing performance over a wide operating range. This analytical study relies on a mathematical model of a rotor fitted with N identical, general-path absorbers, and utilizes perturbation techniques to obtain analytical estimates for the response of the rotor and the absorbers. The results are used to select path parameters based on selected performance measures, and the results are verified via simulation studies. It is shown that slightly overtuned cycloidal paths provide excellent vibration reduction characteristics and prevent the occurrence of nonlinear instabilities and vibration localization in the response of the absorbers.

  19. Control of Torsional Vibrations by Pendulum Masses

    NASA Technical Reports Server (NTRS)

    Stieglitz, Albert

    1942-01-01

    Various versions of pendulum masses have been developed abroad within the past few years by means of which resonant vibrations of rotating shafts can be eliminated at a given tuning. They are already successfully employed on radial engines in the form of pendulous counterweights. Compared with the commonly known torsional vibration dampers, the pendulum masses have the advantage of being structurally very simple, requiring no internal damping and being capable of completely eliminating certain vibrations. Unexplained, so far, remains the problem of behavior of pendulum masses in other critical zones to which they are not tuned, their dynamic behavior at some tuning other than in resonance, and their effect within a compound vibration system and at simultaneous application of several differently tuned pendulous masses. These problems are analyzed in the present report. The results constitute an enlargement of the scope of application of pendulum masses, especially for in-line engines. Among other things it is found that the natural frequency of a system can be raised by means of a correspondingly tuned pendulum mass. The formulas necessary for the design of any practical version are developed, and a pendulum mass having two different natural frequencies simultaneously is described.

  20. Influence of mistuning on blade torsional flutter

    NASA Technical Reports Server (NTRS)

    Srinivasan, A. V.

    1980-01-01

    An analytical technique for the prediction of fan blade flutter was evaluated by utilizing first stage fan flutter data from tests on an advanced high performance engine. The formulation includes both aerodynamic and mechanical coupling among all the blades of the assembly. Mistuning is accounted for in the analysis so that individual blade inertias, frequencies, or damping can be considered. Airfoil stability was predicted by calculating a flutter determinant, the eigenvalues of which indicate the extent of susceptibility to flutter. When blade to blade differences in frequencies are considered, a stable system is predicted for the test points examined. For a tuned system, it was found that torsional flutter can be predicted at a limited number of interblade phase angles. Examination of these phase angles indicated that they were "close" to the condition of acoustic resonance. For the range of Mach numbers and reduced frequencies considered, the so called subcritical flutter cannot be predicted. The essential influence of mechanical coupling among the blades is to change the frequencies of the system with little or no change in damping; however, aerodynamic coupling together with mechanical coupling could change not only frequencies, but also damping in the system, with a trend toward instability.

  1. Angular momentum and Killing potentials

    NASA Astrophysics Data System (ADS)

    Glass, E. N.

    1996-01-01

    When the Penrose-Goldberg (PG) superpotential is used to compute the angular momentum of an axial symmetry, the Killing potential Q??(?) for that symmetry is needed. Killing potentials used in the PG superpotential must satisfy Penrose's equation. It is proved for the Schwarzschild and Kerr solutions that the Penrose equation does not admit a Q??(?) at finite r and therefore the PG superpotential can only be used to compute angular momentum asymptotically.

  2. Errata for cosmological magnetic fields and string dynamo in axion torsioned spacetime

    E-print Network

    Andrade, L C G

    2015-01-01

    Recently much controversy has been shed on BICEP 2 experiments for the concerning this validity or not and a possible set of new experiments to detect primordial inflation and gravitational waves. Since gravitational waves imply the existence of primordial magnetic fields in this context, C Bonvin, R Durrer and R Marteens [Phys Rev Lett (2014)] have tried to associate the presence of primordial magnetic fields to BICEP 2 by making use of CMB tensor modes. Here we show that by considering torsion dilatonic lagrangean one obtains cosmological magnetic fields of the order of $B\\sim{10^{-10}G}$ which may seed galactic dynamos. Actually this new result came out of a mistake of a recent paper published by myself in JCAP (2014). These results are more in accordance with Bamba results [JCAP (2014)] in the context of teleparallel theory of gravity with Einstein's distant parallelism and torsion. These results also support Einstein-Cartan sort of theories of gravity from well-known recent data.

  3. The angular momentum of the gravitational field and the Poincare group

    E-print Network

    J. W. Maluf; S. C. Ulhoa; F. F. Faria; J. F. da Rocha-Neto

    2006-09-06

    We redefine the gravitational angular momentum in the framework of the teleparallel equivalent of general relativity. In similarity to the gravitational energy-momentum, the new definition for the gravitational angular momentum is coordinate independent. By considering the Poisson brackets in the phase space of the theory, we find that the gravitational energy-momentum and angular momentum correspond to a representation of the Poincar\\'e group. This result allows us to define Casimir type invariants for the gravitational field.

  4. Modelling the torsion of thin metal wires by distortion gradient plasticity

    NASA Astrophysics Data System (ADS)

    Bardella, Lorenzo; Panteghini, Andrea

    2015-05-01

    Under small strains and rotations, we apply a phenomenological higher-order theory of distortion gradient plasticity to the torsion problem, here assumed as a paradigmatic benchmark of small-scale plasticity. Peculiar of the studied theory, proposed about ten years ago by Morton E. Gurtin, is the constitutive inclusion of the plastic spin, affecting both the free energy and the dissipation. In particular, the part of the free energy, called the defect energy, which accounts for Geometrically Necessary Dislocations, is a function of Nye's dislocation density tensor, dependent on the plastic distortion, including the plastic spin. For the specific torsion problem, we implement this distortion gradient plasticity theory into a Finite Element (FE) code characterised by implicit (Backward Euler) time integration, numerically robust and accurate for both viscoplastic and rate-independent material responses. We show that, contrariwise to other higher-order theories of strain gradient plasticity (neglecting the plastic spin), the distortion gradient plasticity can predict some strengthening even if a quadratic defect energy is chosen. On the basis of the results of many FE analyses, concerned with (i) cyclic loading, (ii) switch in the higher-order boundary conditions during monotonic plastic loading, (iii) the use of non-quadratic defect energies, and (iv) the prediction of experimental data, we mainly show that (a) including the plastic spin contribution in a gradient plasticity theory is highly recommendable to model small-scale plasticity, (b) less-than-quadratic defect energies may help in describing the experimental results, but they may lead to anomalous cyclic behaviour, and (c) dissipative (unrecoverable) higher-order finite stresses are responsible for an unexpected mechanical response under non-proportional loading.

  5. Experimental-numerical investigation of the dynamic stability of flexural-torsional vibrations of compressor blades under conditions of attached and separated flow. Part 1. Procedure and equipment for the determination of nonstationary aerodynamic characteristics

    Microsoft Academic Search

    A. L. Stel’makh; A. D. Len; A. P. Zinkovskii

    2007-01-01

    We present the results of investigations of the aerodynamic stability of flexural-torsional vibrations of compressor blades\\u000a under conditions of attached and separated flow with regard for the cross and mutual aerodynamic links of the blades in a\\u000a broad range of variations of the phase shift, the ratio of the amplitudes of translational and angular components of their\\u000a displacements, and the

  6. Numerical modeling of pendulum dampers in torsional systems

    SciTech Connect

    Johnston, P.R.; Shusto, L.M.

    1986-01-01

    Centrifugal pendulum-design dampers are utilized in torsional systems to reduce the vibration amplitude at certain objectionable torsional speeds. The damper is tuned by proper design of its mass, dimensions, and position on a carrier disk, which is rigidly attached to the torsional system. The effects of the pendulum damper on the response of the torsional system may be included by modifying the structural model to include a separate damper element representing each order of the pendulum damper. The stiffness and mass matrices for a damper element are dependent upon the order of vibration being dampened, the mass, and the geometry of the damper. A general form of the mass and stiffness equations for a simple centrifugal pendulum damper are derived from first principles using Lagrange's equations of motion. The analysis of torsional systems with pendulum dampers utilizing the mass and stiffness properties developed is included in the program SHAMS. SHAMS calculates the steady-state response of a system of springs and masses to harmonic loads using modal superposition. The response of a crankshaft system with and without the pendulum dampers are included as a case study.

  7. Elevated temperature axial and torsional fatigue behavior of Haynes 188

    NASA Technical Reports Server (NTRS)

    Bonacuse, Peter J.; Kalluri, Sreeramesh

    1992-01-01

    The results of high-temperature axial and torsional low-cycle fatigue experiments performed on Haynes 188, a wrought cobalt-base superalloy, are reported. Fatigue tests were performed at 760 C in air on thin-walled tubular specimens at various ranges under strain control. Data are also presented for coefficient of thermal expansion, elastic modulus, and shear modulus at various temperatures from room to 1000 C, and monotonic and cyclic stress-strain curves in tension and in shear at 760 C. The data set is used to evaluate several multiaxial fatigue life models (most were originally developed for room temperature multiaxial life prediction) including von Mises equivalent strain range (ASME boiler and pressure vessel code), Manson-Halford, Modified Multiaxiality Factor (proposed here), Modified Smith-Watson-Topper, and Fatemi-Socie-Kurath. At von Mises equivalent strain ranges (the torsional strain range divided by the square root of 3, taking the Poisson's ratio to be 0.5), torsionally strained specimens lasted, on average, factors of 2 to 3 times longer than axially strained specimens. The Modified Multiaxiality Factor approach shows promise as a useful method of estimating torsional fatigue life from axial fatigue data at high temperatures. Several difficulties arose with the specimen geometry and extensometry used in these experiments. Cracking at extensometer probe indentations was a problem at smaller strain ranges. Also, as the largest axial and torsional strain range fatigue tests neared completion, a small amount of specimen buckling was observed.

  8. Elevated temperature axial and torsional fatigue behavior of Haynes 188

    NASA Astrophysics Data System (ADS)

    Bonacuse, Peter J.; Kalluri, Sreeramesh

    1992-06-01

    The results of high-temperature axial and torsional low-cycle fatigue experiments performed on Haynes 188, a wrought cobalt-base superalloy, are reported. Fatigue tests were performed at 760 C in air on thin-walled tubular specimens at various ranges under strain control. Data are also presented for coefficient of thermal expansion, elastic modulus, and shear modulus at various temperatures from room to 1000 C, and monotonic and cyclic stress-strain curves in tension and in shear at 760 C. The data set is used to evaluate several multiaxial fatigue life models (most were originally developed for room temperature multiaxial life prediction) including von Mises equivalent strain range (ASME boiler and pressure vessel code), Manson-Halford, Modified Multiaxiality Factor (proposed here), Modified Smith-Watson-Topper, and Fatemi-Socie-Kurath. At von Mises equivalent strain ranges (the torsional strain range divided by the square root of 3, taking the Poisson's ratio to be 0.5), torsionally strained specimens lasted, on average, factors of 2 to 3 times longer than axially strained specimens. The Modified Multiaxiality Factor approach shows promise as a useful method of estimating torsional fatigue life from axial fatigue data at high temperatures. Several difficulties arose with the specimen geometry and extensometry used in these experiments. Cracking at extensometer probe indentations was a problem at smaller strain ranges. Also, as the largest axial and torsional strain range fatigue tests neared completion, a small amount of specimen buckling was observed.

  9. Elevated temperature axial and torsional fatigue behavior of Haynes 188

    NASA Technical Reports Server (NTRS)

    Bonacuse, Peter J.; Kalluri, Sreeramesh

    1995-01-01

    The results are reported for high-temperature axial and torsional low-cycle fatigue experiments performed at 760 C in air on thin-walled tubular specimens of Haynes 188, a wrought cobalt-based superalloy. Data are also presented for mean coefficient of thermal expansion, elastic modulus, and shear modulus at various temperatures from room to 1000 C, and monotonic and cyclic stress-strain curves in tension and in shear at 760 C. This data set is used to evaluate several multiaxial fatigue life models (most were originally developed for room temperature multiaxial life prediction) including von Mises equivalent strain range (ASME Boiler and Pressure Code), Manson-Halford, modified multiaxiality factor (proposed in this paper), modified Smith-Watson-Topper, and Fatemi-Socie-Kurath. At von Mises equivalent strain ranges (the torsional strain range divided by the square root of 3, taking the Poisson's ratio to be 0.5), torsionally strained specimens lasted, on average, factors of 2 to 3 times longer than axially strained specimens. The modified multiaxiality factor approach shows promise as a useful method of estimating torsional fatigue life from axial fatigue data at high temperatures. Several difficulties arose with the specimen geometry and extensometry used in these experiments. Cracking at extensometer probe indentations was a problem at smaller strain ranges. Also, as the largest axial and torsional strain range fatigue tests neared completion, a small amount of specimen buckling was observed.

  10. On updating torsion angles of molecular conformations.

    PubMed

    Choi, Vicky

    2006-01-01

    A conformation of a molecule is defined by the relative positions of atoms and by the chirality of asymmetric atoms in the molecule. The three main representations for conformations of molecules are Cartesian coordinates, a distance geometry descriptor (which consists of a distance matrix and the signs of the volumes of quadruples of atoms), and internal coordinates. In biochemistry, conformational changes of a molecule are usually described in terms of internal coordinates. However, for many applications, such as molecular docking, the Cartesian coordinates of atoms are needed for computation. Although, for each conformational change, the Cartesian coordinates of atoms can be updated in linear time (which is optimal asymptotically), the constant factor becomes significant if a large number of updates are needed. Zhang and Kavraki (J. Chem. Inf. Comput. Sci. 2002, 42, 64-70) examined three methods: the simple rotations, the Denavit-Hartenberg local frames, and the atom-group local frames. On the basis of their implementations, they showed that the atom-group local frames are more efficient than the other two. In this paper, by expressing the torsion-angle change as a composition of translations and rotations, we observe that the simple rotations can be implemented in an efficient way by taking advantage of consecutive operations. Both quantitative and experimental comparisons show that the improved simple rotations, in which rotations are expressed in unit quaternions, are as efficient as the atom-group local frames and, thus, have the advantage of avoiding the need of precomputations of a set of local frames and transformations between them. PMID:16426078

  11. Angular momentum of isolated systems

    NASA Astrophysics Data System (ADS)

    Helfer, Adam D.

    2007-12-01

    Penrose’s twistorial approach to the definition of angular momentum at null infinity is developed so that angular momenta at different cuts can be meaningfully compared. This is done by showing that the twistor spaces associated with different cuts of mathcal{J}^+ can be identified as manifolds (but not as vector spaces). The result is a well-defined, Bondi-Metzner-Sachs-invariant notion of angular momentum in a radiating space-time; the difficulties and ambiguities previously encountered are attached to attempts to express this in special-relativistic terms, and in particular to attempts to identify a single Minkowski space of origins. Unlike the special-relativistic case, the angular momentum cannot be represented by a purely j = 1 quantity M ab , but has higher- j contributions as well. Applying standard kinematic prescriptions, these higher- j contributions are shown to correspond precisely to the shear. Thus it appears that shear and angular momentum should be regarded as different aspects of a single unified concept.

  12. Angular momentum of isolated systems

    E-print Network

    Adam D. Helfer

    2007-09-07

    Penrose's twistorial approach to the definition of angular momentum at null infinity is developed so that angular momenta at different cuts can be meaningfully compared. This is done by showing that the twistor spaces associated with different cuts of scri can be identified as manifolds (but not as vector spaces). The result is a well-defined, Bondi-Metzner-Sachs-invariant notion of angular momentum in a radiating space-time; the difficulties and ambiguities previously encountered are attached to attempts to express this in special-relativistic terms, and in particular to attempts to identify a single Minkowski space of origins. Unlike the special-relativistic case, the angular momentum cannot be represented by a purely j=1 quantity M_{ab}, but has higher-j contributions as well. Applying standard kinematic prescriptions, these higher-j contributions are shown to correspond precisely to the shear. Thus it appears that shear and angular momentum should be regarded as different aspects of a single unified concept.

  13. Sage basics Problem: Triangulations Problem: Torsion in homology Advertisements, links Algebraic topology in Sage

    E-print Network

    Palmieri, John

    Sage basics Problem: Triangulations Problem: Torsion in homology Advertisements, links Algebraic topology in Sage John H. Palmieri Department of Mathematics University of Washington Cascade Topology Seminar December 1, 2012 Eugene #12;Sage basics Problem: Triangulations Problem: Torsion in homology

  14. Novel fiber optic polarimetric torsion sensor based on polarization-maintaining photonic crystal fiber

    Microsoft Academic Search

    H. Y. Fu; S. K. Khijwania; H. Y. Au; Xinyong Dong; H. Y. Tam; P. K. A. Wai; C. Lu

    2008-01-01

    We proposed and demonstrated the application of a polarization-maintaining photonic crystal fiber for torsion sensing. The sensor has high twist angle resolution and exhibits reduced temperature sensitivity, making it an ideal candidate for torsion sensing.

  15. Edge delamination of composite laminates subject to combined tension and torsional loading

    NASA Technical Reports Server (NTRS)

    Hooper, Steven J.

    1990-01-01

    Delamination is a common failure mode of laminated composite materials. Edge delamination is important since it results in reduced stiffness and strength of the laminate. The tension/torsion load condition is of particular significance to the structural integrity of composite helicopter rotor systems. Material coupons can easily be tested under this type of loading in servo-hydraulic tension/torsion test stands using techniques very similar to those used for the Edge Delamination Tensile Test (EDT) delamination specimen. Edge delamination of specimens loaded in tension was successfully analyzed by several investigators using both classical laminate theory and quasi-three dimensional (Q3D) finite element techniques. The former analysis technique can be used to predict the total strain energy release rate, while the latter technique enables the calculation of the mixed-mode strain energy release rates. The Q3D analysis is very efficient since it produces a three-dimensional solution to a two-dimensional domain. A computer program was developed which generates PATRAN commands to generate the finite element model. PATRAN is a pre- and post-processor which is commonly used with a variety of finite element programs such as MCS/NASTRAN. The program creates a sufficiently dense mesh at the delamination crack tips to support a mixed-mode fracture mechanics analysis. The program creates a coarse mesh in those regions where the gradients in the stress field are low (away from the delamination regions). A transition mesh is defined between these regions. This program is capable of generating a mesh for an arbitrarily oriented matrix crack. This program significantly reduces the modeling time required to generate these finite element meshes, thus providing a realistic tool with which to investigate the tension torsion problem.

  16. ANGULAR MOMENTUM: AN APPROACH TO COMBINATORIAL SPACETIME

    E-print Network

    Baez, John

    ANGULAR MOMENTUM: AN APPROACH TO COMBINATORIAL SPACE­TIME ROGER PENROSE I want to describe an idea­time in a very intimate way, is in angular momentum. The idea here, then, is to start with the concept of angular momentum--- here one has a discrete spectrum---and use the rules for combining angular This paper

  17. Coupled bending-bending-torsion flutter of a mistuned cascade with nonuniform blades

    NASA Technical Reports Server (NTRS)

    Kaza, K. R. V.; Kielb, R. E.

    1982-01-01

    A set of aeroelastic equations describing the motion of an arbitrarily mistuned cascade with flexible, pretwisted, nonuniform blades is developed using an extended Hamilton's principle. The derivation of the equations has its basis in the geometric nonlinear theory of elasticity in which the elongations and shears are negligible compared to unity. A general expression for foreshortening of a blade is derived and is explicity used in the formulation. The blade aerodynamic loading in the subsonic and supersonic flow regimes is obtained from two dimensional, unsteady, cascade theories. The aerodynamic, inertial and structural coupling between the bending (in two planes) and torsional motions of the blade is included. The equations are used to investigate the aeroelastic stability and to quantify the effect of frequency mistuning on flutter in turbofans. Results indicate that a moderate amount of intentional mistuning has enough potential to alleviate flutter problems in unshrouded, high aspect ratio turbofans.

  18. Nonlinear Curvature Expressions for Combined Flapwise Bending, Chordwise Bending, Torsion and Extension of Twisted Rotor Blades

    NASA Technical Reports Server (NTRS)

    Kvaternik, R. G.; Kaza, K. R. V.

    1976-01-01

    The nonlinear curvature expressions for a twisted rotor blade or a beam undergoing transverse bending in two planes, torsion, and extension were developed. The curvature expressions were obtained using simple geometric considerations. The expressions were first developed in a general manner using the geometrical nonlinear theory of elasticity. These general nonlinear expressions were then systematically reduced to four levels of approximation by imposing various simplifying assumptions, and in each of these levels the second degree nonlinear expressions were given. The assumptions were carefully stated and their implications with respect to the nonlinear theory of elasticity as applied to beams were pointed out. The transformation matrices between the deformed and undeformed blade-fixed coordinates, which were needed in the development of the curvature expressions, were also given for three of the levels of approximation. The present curvature expressions and transformation matrices were compared with corresponding expressions existing in the literature.

  19. FREQUENCY FILTERING OF TORSIONAL ALFVEN WAVES BY CHROMOSPHERIC MAGNETIC FIELD

    SciTech Connect

    Fedun, V.; Erdelyi, R. [School of Mathematics and Statistics, University of Sheffield, Hounsfield Road, Hicks Building, Sheffield S3 7RH (United Kingdom); Verth, G. [School of Computing, Engineering and Information Sciences, Northumbria University, Newcastle Upon Tyne NE1 8ST (United Kingdom); Jess, D. B. [Astrophysics Research Centre, School of Mathematics and Physics, Queen's University, Belfast University Road, Belfast BT7 1NN (United Kingdom)

    2011-10-20

    In this Letter, we demonstrate how the observation of broadband frequency propagating torsional Alfven waves in chromospheric magnetic flux tubes can provide valuable insight into their magnetic field structure. By implementing a full nonlinear three-dimensional magnetohydrodynamic numerical simulation with a realistic vortex driver, we demonstrate how the plasma structure of chromospheric magnetic flux tubes can act as a spatially dependent frequency filter for torsional Alfven waves. Importantly, for solar magnetoseismology applications, this frequency filtering is found to be strongly dependent on magnetic field structure. With reference to an observational case study of propagating torsional Alfven waves using spectroscopic data from the Swedish Solar Telescope, we demonstrate how the observed two-dimensional spatial distribution of maximum power Fourier frequency shows a strong correlation with our forward model. This opens the possibility of beginning an era of chromospheric magnetoseismology, to complement the more traditional methods of mapping the magnetic field structure of the solar chromosphere.

  20. A novel low-profile shape memory alloy torsional actuator

    NASA Astrophysics Data System (ADS)

    Paik, Jamie K.; Hawkes, Elliot; Wood, Robert J.

    2010-12-01

    This paper presents low-profile torsional actuators applicable for mesoscale and microscale robots. The primary actuator material is thermally activated Ni-Ti shape memory alloy (SMA), which exhibits remarkably high torque density. Despite the advantages of SMAs for actuator applications—high strain, silent operation, and mechanical simplicity—the response time and energy efficiency limit overall performance. As an alternative to SMA wires, thin SMA sheets are used to fabricate effective yet compact torsional actuators. Also, instead of using conventional Joule heating, an external Ni-Cr heating element is utilized to focus heat on the regions of highest required strain. Various design parameters and fabrication variants are described and experimentally explored in actuator prototypes. Controlled current profiles and discrete heating produces a 20% faster response time with 40% less power consumption as compared to Joule heating in a low-profile (sub-millimeter) torsional actuator capable of 180° motion.

  1. Variations in atmospheric angular momentum

    NASA Technical Reports Server (NTRS)

    Rosen, R. D.; Salstein, D. A.

    1981-01-01

    Twice-daily values of the atmosphere's angular momentum about the polar axis during the five years from 1976 through 1980 are presented in graphs and a table. The compilation is based on a global data set, incorporating 90 percent of the mass of the atmosphere. The relationship between changes in the angular momentum of the atmosphere and changes in the length of day is described, as are the main sources of error in the data. The variability in angular momentum is revealed in a preliminary fashion by means of a spectral decomposition. The data presented should stimulate comparisons with other measures of the length of day and so provide a basis for greater understanding of Earth-atmosphere interactions.

  2. Inflation in $R + R^2$ Gravity with Torsion

    E-print Network

    Chih-Hung Wang; Yu-Huei Wu

    2009-02-06

    We examine an inflationary model in $R + R^2$ gravity with torsion, where $R^2$ denotes five independent quadratic curvature invariants; it turns out that only two free parameters remain in this model. We show that the behavior of the scale factor $a(t)$ is determined by two scalar fields, axial torsion $\\chi(t)$ and the totally anti-symmetric curvature $E(t)$, which satisfy two first-order differential equations. Considering $\\dot{\\chi}\\approx 0$ during inflation leads to a power-law inflation: $a \\sim (t+ A)^p$ where $1inflation, $\\chi$ and $E$ will enter into an oscillatory phase.

  3. Fermion condensate from torsion in the reheating era after inflation

    NASA Astrophysics Data System (ADS)

    Weller, Joel M.

    2013-10-01

    The inclusion of Dirac fermions in Einstein-Cartan gravity leads to a four-fermion interaction mediated by nonpropagating torsion, which can allow for the formation of a Bardeen-Cooper-Schrieffer condensate. By considering a simplified model in 2+1 spacetime dimensions, we show that even without an excess of fermions over antifermions, the nonthermal distribution arising from preheating after inflation can give rise to a fermion condensate generated by torsion. We derive the effective Lagrangian for the spacetime-dependent pair field describing the condensate in the extreme cases of nonrelativistic and massless fermions, and show that it satisfies the Gross-Pitaevski equation for a gapless, propagating mode.

  4. The torsional fatigue properties of titanium-alloy spring wire

    Microsoft Academic Search

    E. L. Hayman; D. W. Greenwood; B. G. Martin

    1977-01-01

    The absence of any torsional fatigue-test data on currently used titanium-alloy spring wire along with inconsistent fatigue-test data derived from earlier test programs prompted this investigation. The torsional fatigue testing was performed on straight lengths of 13V–11Cr–3Al titanium-alloy spring wire in diameters of 0.148 in. (0.376 cm), 0.225 in. (0.572 cm) and 0.374 in. (0.950 cm) considered as representative. A

  5. Coated Fused Silica Fibers for Enhanced Sensitivity Torsion Pendulum

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Horowitz, Jordan; Camp, Jordan

    2007-01-01

    In order to investigate the fundamental thermal noise limit of a torsion pendulum using a fused silica fiber, we systematically measured and modeled the mechanical losses of thin fused silica fibers coated by electrically conductive thin metal films. Our results indicate that it is possible to achieve a thermal noise limit for coated silica lower by a factor between 3 and 9, depending on the silica diameter, compared to the best tungsten fibers available. This will allow a corresponding increase in sensitivity of torsion pendula used for weak force measurements, including the gravitational constant measurement and ground-based force noise testing for the Laser Interferometer Space Antenna (LISA) mission.

  6. The relativistic particle with curvature and torsion of world trajectory

    E-print Network

    S. A. Gogilidze; Yu. S. Surovtsev

    1998-09-27

    Local symmetries of the action for a relativistic particle with curvature and torsion of its world curve in the (2+1)-dimensional space-time are studied. With the help of the method, worked out recently by the authors (Phys.Rev., D56, 1135, 1142 (1997)), first the local-symmetry transformations are obtained both in the phase and configuration space. At the classical level, the dependence of the particle mass on the parameters of curvature and torsion and the Regge trajectory are obtained. It is shown that the tachyonic sector can be removed by a proper gauge choice.

  7. Torsional Newton–Cartan geometry and the Schrödinger algebra

    NASA Astrophysics Data System (ADS)

    Bergshoeff, Eric A.; Hartong, Jelle; Rosseel, Jan

    2015-07-01

    We show that by gauging the Schrödinger algebra with critical exponent z and imposing suitable curvature constraints, that make diffeomorphisms equivalent to time and space translations, one obtains a geometric structure known as (twistless) torsional Newton–Cartan geometry (TTNC). This is a version of torsional Newton–Cartan geometry (TNC) in which the timelike vielbein {? }? must be hypersurface orthogonal. For z = 2 this version of TTNC geometry is very closely related to the one appearing in holographic duals of z = 2 Lifshitz space-times based on Einstein gravity coupled to massive vector fields in the bulk. For z\

  8. Spin connection as Lorentz gauge field: propagating torsion

    E-print Network

    Cianfrani, Francesco; Scopelliti, Vincenzo

    2015-01-01

    We propose a modified gravitational action containing besides the Einstein-Hilbert term some quadratic contributions resembling the Yang-Mills lagrangian for the spin connections. We outline how a propagating torsion arises and we solve explicitly the linearised equations of motion on a Minkowski background. We identify among torsion components six degrees of freedom: one is carried by a pseudo-scalar particle, five by a tachyon field. By adding spinor fields, we point out how only the pseudo-scalar particle couples directly with fermions and we evaluate the associated coupling constant, which is suppressed by the ratio between fermion and Planck masses.

  9. Spin connection as Lorentz gauge field: propagating torsion

    E-print Network

    Francesco Cianfrani; Giovanni Montani; Vincenzo Scopelliti

    2015-05-05

    We propose a modified gravitational action containing besides the Einstein-Hilbert term some quadratic contributions resembling the Yang-Mills lagrangian for the spin connections. We outline how a propagating torsion arises and we solve explicitly the linearised equations of motion on a Minkowski background. We identify among torsion components six degrees of freedom: one is carried by a pseudo-scalar particle, five by a tachyon field. By adding spinor fields, we point out how only the pseudo-scalar particle couples directly with fermions and we evaluate the associated coupling constant, which is suppressed by the ratio between fermion and Planck masses.

  10. Automated Angular Momentum Recoupling Algebra

    NASA Astrophysics Data System (ADS)

    Williams, H. T.; Silbar, Richard R.

    1992-04-01

    We present a set of heuristic rules for algebraic solution of angular momentum recoupling problems. The general problem reduces to that of finding an optimal path from one binary tree (representing the angular momentum coupling scheme for the reduced matrix element) to another (representing the sub-integrals and spin sums to be done). The method lends itself to implementation on a microcomputer, and we have developed such an implementation using a dialect of LISP. We describe both how our code, called RACAH, works and how it appears to the user. We illustrate the use of RACAH for several transition and scattering amplitude matrix elements occurring in atomic, nuclear, and particle physics.

  11. Measuring Angular Size and Distance

    NSDL National Science Digital Library

    2012-08-03

    This is an activity about measuring angular size and understanding the solar and lunar proportions that result in solar eclipses. Learners will use triangles and proportions to create a shoebox eclipse simulator. They will then apply what they learn about angular size to predict the diameter and distance of one object that can be eclipsed by another. They will also complete three journal assignments to record observations and conceptual understanding. This activity derives from those demonstrated in the NASA CONNECT television series episode, titled Path of Totality.

  12. Torsional Vibration Signal Simulation and Analysis of Dual-mass Flywheel Based on LabVIEW

    Microsoft Academic Search

    Zhou Bin; Jiang Zhengfeng; Zhao Guangming

    2010-01-01

    The torsional vibration of the engine has an important impact on car's safety and ride comfort. Dual-mass flywheel, as a new type component of transmission system can reduce the engine output shaft's torsional vibration effectively. Based on the analysis of torsional vibration waveform, the paper proposes a detection method for DMF and brings forward a virtual instrument simulation test system

  13. Intrauterine torsion of a wandering spleen presenting as an abdominal cystic swelling

    Microsoft Academic Search

    Akhtar Nawaz; Alic Jacobsz; Hilal Matta; Ghassan Al-Khouder; Farhan Ansari; Ahmed H. Al-Salem

    2000-01-01

    Wandering spleen is a rare clinical condition that presents commonly with splenic infarction secondary to torsion. Intrauterine torsion of a wandering spleen, however, is extremely rare. An unusual case of intrauterine torsion of a wandering spleen presenting as an abdominal mass is reported. J Pediatr Surg 35:1508-1510.

  14. QUASI-STATIC AND DYNAMIC TORSION TESTING OF CERAMIC COATINGS USING HIGH-SPEED PHOTOGRAPHY

    E-print Network

    Espinosa, Horacio D.

    QUASI-STATIC AND DYNAMIC TORSION TESTING OF CERAMIC COATINGS USING HIGH-SPEED PHOTOGRAPHY François were performed on a Kolsky bar apparatus modified for torsion loading. High-speed photography was used-static and dynamic loading. A Kolsky bar [6] modified for torsional loading was used. High-Speed Photography

  15. Continuity conditions and torsion angles from ssNMR orientational restraints

    Microsoft Academic Search

    S. Achuthan; T. Asbury; J. Hu; R. Bertram; T. A. Cross; J. R. Quine

    2008-01-01

    The backbone torsion angle pair (?,?) at each amino acid of a polypeptide is a descriptor of its conformation. One can use chemical shift and dipolar coupling data from solid-state NMR PISEMA experiments to directly calculate the torsion angles for the membrane-spanning portion of a protein. However, degeneracies inherent in the data give rise to multiple potential torsion angles between

  16. A MEASUREMENT OF THE GRAVITATIONAL CONSTANT USING A CRYOGENIC TORSION PENDULUM

    E-print Network

    Newman, Riley D.

    A MEASUREMENT OF THE GRAVITATIONAL CONSTANT USING A CRYOGENIC TORSION PENDULUM M.K. Bantel, E of a measurement of G made using a cryogenic torsion pendulum in the `dynamic' (time-of-swing) mode. We have- lation frequency of a thin-plate torsion pendulum due to a pair of ring-shaped source masses positioned

  17. PROGRESS IN THE MEASUREMENT OF THE GRAVITATIONAL CONSTANT USING A CRYOGENIC TORSION PENDULUM

    E-print Network

    Newman, Riley D.

    PROGRESS IN THE MEASUREMENT OF THE GRAVITATIONAL CONSTANT USING A CRYOGENIC TORSION PENDULUM E a cryogenic torsion pendulum in the "dynamic" (time- of-swing) mode. The total metrology contribution to the G- lation frequency of a thin-plate torsion pendulum due to a pair of ring-shaped source masses positioned

  18. Kinetic description of electron plasma waves with orbital angular momentum

    NASA Astrophysics Data System (ADS)

    Mendonça, J. T.

    2012-11-01

    We describe the kinetic theory of electron plasma waves with orbital angular momentum or twisted plasmons. The conditions for a twisted Landau resonance to exist are established, and this concept is introduced for the first time. Expressions for the kinetic dispersion relation and for the electron Landau damping are derived. The particular case of a Maxwellian plasma is examined in detail. The new contributions to wave dispersion and damping due the orbital angular momentum are discussed. It is shown that twisted plasmons can be excited by rotating electron beams.

  19. Kinetic description of electron plasma waves with orbital angular momentum

    SciTech Connect

    Mendonca, J. T. [IPFN, Instituto Superior Tecnico, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal)

    2012-11-15

    We describe the kinetic theory of electron plasma waves with orbital angular momentum or twisted plasmons. The conditions for a twisted Landau resonance to exist are established, and this concept is introduced for the first time. Expressions for the kinetic dispersion relation and for the electron Landau damping are derived. The particular case of a Maxwellian plasma is examined in detail. The new contributions to wave dispersion and damping due the orbital angular momentum are discussed. It is shown that twisted plasmons can be excited by rotating electron beams.

  20. Angular momentum non conserving symmetries in bosonic models

    E-print Network

    L. Fortunato; W. A. de Graaf

    2011-02-23

    The Levi-Malcev decomposition is applied to bosonic models of quantum mechanics based on unitary Lie algebras u(2), u(2)+u(2), u(3) and u(4) to clearly disentangle semisimple subalgebras. The theory of weighted Dynkin diagrams is then applied to identify conjugacy classes of relevant A_1 subalgebras allowing to introduce a complete classification of new angular momentum non conserving (AMNC) dynamical symmetries. The tensor analysis of the whole algebra based on the new "angular momentum" operators reveals unexpected spinors to occur in purely bosonic models. The new chains of subalgebra can be invoked to set up ANMC bases for diagonalization.

  1. Angular output of hollow, metal-lined, waveguide Raman sensors

    SciTech Connect

    Biedrzycki, Stephen; Buric, Michael P.; Falk, Joel; Woodruff, Steven D.

    2012-04-20

    Hollow, metal-lined waveguides used as gas sensors based on spontaneous Raman scattering are capable of large angular collection. The collection of light from a large solid angle implies the collection of a large number of waveguide modes. An accurate estimation of the propagation losses for these modes is required to predict the total collected Raman power. We report a theory/experimental comparison of the Raman power collected as a function of the solid angle and waveguide length. New theoretical observations are compared with previous theory appropriate only for low-order modes. A cutback experiment is demonstrated to verify the validity of either theory. The angular distribution of Raman light is measured using aluminum and silver-lined waveguides of varying lengths.

  2. Angular momentum from tidal torques

    Microsoft Academic Search

    Joshua Barnes; George Efstathiou

    1987-01-01

    The authors describe results for the origin of angular momentum of bound objects in large cosmological N-body simulations. Three sets of models are analyzed: one with white-noise initial conditions and two in which the initial conditions have more power on large scales, as predicted in models with cold dark matter (CDM). Statistical analysis of large catalogs of objects shows that

  3. Unified Angular Momentum of Dyons

    E-print Network

    Shalini Dangwal; P. S. Bisht; O. P. S. Negi

    2006-08-22

    Unified quaternionic angular momentum for the fields of dyons and gravito-dyons has been developed and the commutation relations for dynamical variables are obtained in compact and consistent manner. Demonstrating the quaternion forms of unified fields of dyons (electromagnetic fields) and gravito-dyons (gravito-Heavisidian fields of linear gravity), corresponding quantum equations are reformulated in compact, simpler and manifestly covariant way.

  4. Olympic Wrestling and Angular Momentum.

    ERIC Educational Resources Information Center

    Carle, Mark

    1988-01-01

    Reported is the use of a wrestling photograph in a noncalculus introductory physics course. The photograph presents a maneuver that could serve as an example for a discussion on equilibrium, forces, torque, and angular motion. Provided are some qualitative thoughts as well as quantitative calculations. (YP)

  5. The lunar angular momentum problem

    NASA Technical Reports Server (NTRS)

    Weidenschilling, S. J.

    1984-01-01

    Formation of the Moon by classical Darwin-type fission of a rapidly spinning proto-Earth is discussed. The relationship of angular momentum to accretion disks is examined. The co-accretion scenario and Darwin-type fission are compared and evaluated.

  6. Constitutive modeling of tension-torsion coupling and tension-compression asymmetry in NiTi shape memory alloys

    NASA Astrophysics Data System (ADS)

    Mehrabi, Reza; Kadkhodaei, Mahmoud; Elahinia, Mohammad

    2014-07-01

    A three-dimensional phenomenological model based on microplane theory is extended to capture the coupling effects between tension and torsion in complex multiaxial loadings. Inelastic strain in a microplane approach is a component of transformation strain and anisotropic strain. Since the anisotropy effect is induced during martensitic transformation, anisotropic strain is defined as a function of transformation strain. Out-of-plane strain is induced in simple tension and pure torsion in free-end conditions. Anisotropy tensor is experimentally extracted and is used in the proposed model to predict the behavior in multiaxial loading. The ability of this extended microplane model to predict the tension-torsion coupling effects as well as the induced transformation anisotropic behavior of NiTi shape memory alloys is demonstrated. In addition, the microplane model is modified to capture the asymmetric behavior in tension and compression during uniaxial and multiaxial loadings. To this end, numerical correlations between the results of the modified microplane model are compared with experimental results to demonstrate the validity of the extended model.

  7. Angular and spectrally resolved investigation of single particles by darkfield scattering microscopy.

    PubMed

    Rothe, Thomas; Schmitz, Michael; Kienle, Alwin

    2012-11-01

    A darkfield scattering microscope has been constructed that enables both angular and spectrally resolved measurements of elastic scattering patterns. The comparison of the angular and spectral resolution modes is shown in detail. Angular patterns of the backscattered light by homogeneous polystyrene spheres were measured at 57 wavelengths and the diameters of the single spheres were determined by using Mie theory at each wavelength. The mean diameter values were estimated in the angular mode with a relative standard deviation of 0.25% or less. Spectral scattering patterns of the same beads were investigated and the diameters were determined and compared with the results of the angular measurements. The estimated diameter values in the angular and the spectral mode were in an excellent agreement with deviations of less than 0.20%. PMID:23214188

  8. Nuclear pairing at finite temperature and angular momentum

    SciTech Connect

    Dang, N. Dinh [Heavy-Ion Nuclear Physics Laboratory, Nishina Center for Accelerator-Based Science, RIKEN 2-1 Hirosawa, Wako city, 351-0198 Saitama, Japan and Institute for Nuclear Science and Technique, Hanoi (Viet Nam); Hung, N. Quang [Heavy-Ion Nuclear Physics Laboratory, Nishina Center for Accelerator-Based Science, RIKEN 2-1 Hirosawa, Wako city, 351-0198 Saitama (Japan)

    2009-01-28

    We propose an approach to nuclear pairing at finite temperature and angular momentum. This approach includes the effects due to the quasiparticle-number fluctuation and dynamic coupling to pair vibrations within the self-consistent quasiparticle random-phase approximation. The pairing gaps, total energies, and heat capacities are calculated within a doubly folded multilevel model as well as several realistic nuclei. The results obtained show that, in the region of moderate and strong couplings, the sharp transition between the superconducting and normal phases is smoothed out. This is manifested in a thermal pairing gap, which does not collapse at a critical temperature predicted by the conventional Bardeen-Cooper-Schrieffer's (BCS) theory, but has a tail extended to high temperatures. Moreover, this approach also predicts the appearance of a thermally assisted pairing at finite angular momentum. The effect of backbending of the momentum of inertia as a function of the square of angular velocity is also discussed.

  9. Generalised models for torsional spine and fan magnetic reconnection

    E-print Network

    Pontin, D I; Galsgaard, K

    2011-01-01

    Three-dimensional null points are present in abundance in the solar corona, and the same is likely to be true in other astrophysical environments. Recent studies suggest that reconnection at such 3D nulls may play an important role in the coronal dynamics. In this paper the properties of the torsional spine and torsional fan modes of magnetic reconnection at 3D nulls are investigated. New analytical models are developed, which for the first time include a current layer that is spatially localised around the null, extending along either the spine or the fan of the null. These are complemented with numerical simulations. The principal aim is to investigate the effect of varying the degree of asymmetry of the null point magnetic field on the resulting reconnection process - where previous studies always considered a non-generic radially symmetric null. The geometry of the current layers within which torsional spine and torsional fan reconnection occur is found to be strongly dependent on the symmetry of the magn...

  10. Effect of bilateral superior oblique split lengthening on torsion

    PubMed Central

    Jethani, Jitendra; Shah, Kuntal; Amin, Sonal

    2015-01-01

    Introduction: Superior oblique split lengthening (SOSL) is done for weakening of superior oblique. It corrects the superior oblique overaction (SOOA) and A pattern. Its effect on the torsion of the eye is not known. We present our data on the effect of this particular procedure on torsion. Materials and Methods: We did a study of 16 patients (32 eyes) who underwent bilateral SOSL and compared the disc foveal angle (DFA) preoperatively and postoperatively. The split lengthening was done from 4 mm to 7 mm depending upon the overaction of superior oblique. Results: The mean age was 15.3 ± 8.4 years. Mean preoperative DFA in the right eye (RE) was ?3.9° and in the left eye (LE) was ?2.9°. Mean postoperative DFA in RE was 0.2° and in LE was 0.9°. The mean change in the DFA for RE was 4.1° ± 1.3° and for LE was 3.8° ± 1.2°. All the patients were aligned horizontally within 6 prism diopter and no pattern and no diplopia postoperatively. The A pattern was corrected in all the patient postsurgery. For each mm of surgery, an improvement of 0.8° was seen in the DFA. Conclusion: We report the effect of SOSL on torsion. The SOSL reduces intorsion postsurgery and is, therefore, a valuable procedure in SOOA where both pattern and in torsion needs to be corrected. PMID:25971171

  11. Quaternionic Torsion Geometry, Superconformal Symmetry and T-duality

    SciTech Connect

    Swann, Andrew [Department of Mathematics and Computer Science, University of Southern Denmark, Campusvej 55, 5230 Odense M (Denmark)

    2009-02-02

    HyperKaehler metrics with torsion (HKT metrics) are constructed via superconformal symmetry. It is shown how T-duality interpreted as a twist construction for circle actions provides a number of compact simply-connected examples. Further applications of the twist construction are discussed to obtain compact simply-connected HKT manifolds with few symmetries and to construct all HKT nilmanifolds.

  12. Compressive and torsional behaviour of Kevlar 49 fibre

    Microsoft Academic Search

    S. J. Deteresa; S. R. Allen; R. J. Farris; R. S. Porter

    1984-01-01

    The mechanical anisotropy of an aromatic polyamide fibre, Kevlar 49, was studied in tension, compression and torsion. A new technique involved applying small and defined compressive strains to filaments by bonding them to one side of a beam which is subsequently bent to compress the fibres. Using scanning electron and optical microscopy, fibres were shown to form regularly-spaced helical kink

  13. Torsion of an ectopic liver in a young child

    Microsoft Academic Search

    Hussain B. Elsayes; Mohydin A. Elzein; Abdel Melik Abdel Razik; Isaac O. Olude

    2005-01-01

    A large ectopic liver nodule connected to the greater omentum had undergone infarction and separation because of torsion of its connecting stalk and was the cause of acute abdominal pain and elevated liver enzymes in a young female child. At laparotomy for a suspected perforated appendicitis, a hemorrhagic peritoneal fluid was found, together with an intraperitoneal solid mass lying freely

  14. L 2 -torsion of hyperbolic manifolds Eckehard Hess Thomas Schick

    E-print Network

    L 2 -torsion of hyperbolic manifolds Eckehard Hess Thomas Schick to appear in Manuscripta Mathematica Eckehard Hess Thomas Schick Fachbereich Mathematik Fachbereich Mathematik Universitat Mainz Universitat Munster Einsteinstr. 62 55099 Mainz, Germany 48149 Munster, Germany hess

  15. FILTRATION ASSOCIATED TO TORSION SEMI-STABLE REPRESENTATIONS

    E-print Network

    Liu, Tong

    FILTRATION ASSOCIATED TO TORSION SEMI-STABLE REPRESENTATIONS TONG LIU Abstract. Let p be an odd prime, K a finite extension of Qp and G := Gal(Qp/K) the Galois group. We construct and study filtration type. 1 Contents 1. Introduction 2 2. Filtration encoded in p-adic Hodge data 3 2.1. Preliminary

  16. FILTRATION ASSOCIATED TO TORSION SEMI-STABLE REPRESENTATIONS

    E-print Network

    Liu, Tong

    FILTRATION ASSOCIATED TO TORSION SEMI-STABLE REPRESENTATIONS TONG LIU Abstract. Let p be an odd prime, K a finite extension of Qp and G := Gal(Qp/K) the Galois group. We construct and study filtration-adic Hodge-Tate type. 1 Contents 1. Introduction 2 2. Filtration encoded in p-adic Hodge data 3 2

  17. Typical Textures, part 2 FCC Torsion, BCC textures

    E-print Network

    Rollett, Anthony D.

    in torsion; the shear direction points to the left in these figures. a) Nickel at =3.6 b) Copper at =3.5 c- carbon steel cold rolled to a reduction in thickness of 80% (approximate equivalent strain of 2); (b

  18. New Approaches to Data Acquisitions in a Torsion Pendulum Experiment

    ERIC Educational Resources Information Center

    Jiang, Daya; Xiao, Jinghua; Li, Haihong; Dai, Qionglin

    2007-01-01

    In this paper, two simple non-contact and cost-effective methods to acquire data in the student laboratory are applied to investigate the motion of a torsion pendulum. The first method is based on a Hall sensor, while the second makes use of an optical mouse.

  19. Equivariant Higher Analytic Torsion and Equivariant Euler Characteristic

    E-print Network

    Bunke, Ulrich

    Introduction Let G be a compact connected Lie group with Lie algebra g. Let I(G) denote the * *ring of Ad) is a differential topological invariant * *of the G-manifold M. In principle the methods of the present paper in this case the higher analyt* *ic torsion can be expressed by a simple topological invariant, namely

  20. Rheology of dolomite: Large strain torsion experiments and natural examples

    Microsoft Academic Search

    Claudio Delle Piane; Luigi Burlini; Karsten Kunze; Peter Brack; Jean Pierre Burg

    2008-01-01

    A set of large strain deformation experiments is presented to better constrain the conditions in which grain size sensitive mechanisms are dominant during deformation of dolomite. Experiments were made on an internally heated gas apparatus equipped with torsion facilities. The rheological data set was fitted to an empirical flow law that allows extrapolation to natural conditions. Fabric evolution with increasing

  1. Torsional springs for two-dimensional dynamic unstructured fluid meshes

    Microsoft Academic Search

    C. Farhat; C. Degand; B. Koobus; M. Lesmoinne

    1998-01-01

    Dynamic fluid grids are commonly used for the solution of flow problems with moving boundaries. They are often represented by a network of fictitious lineal springs that can become unreliable when the fluid mesh undergoes large displacements and\\/or deformations. In this paper, we propose to control the arbitrary motion of two-dimensional dynamic unstructured fluid grids with additional torsional springs. We

  2. Study of properties of sand asphalt using a torsional rheometer

    E-print Network

    Kasula, Lavan Kumar Reddy

    2004-11-15

    . In this work we have used the same Torsional Rheometer with some minor modifications in the design to measure some general properties of Sand Asphalt mixtures. Sand Asphalt mixtures, due to their non-linear viscoelastic character, exhibit `normal stress effects...

  3. Conservative management of accessory spleen torsion in children.

    PubMed

    Scirè, G; Zampieri, N; El-Dalati, G; Camoglio, F S

    2013-08-01

    Accessory spleen torsion is very rare condition especially in children. The aim of this study is to report the conservative treatment option. In April 2009 we observed a 10-year-old child affected by hereditary spherocytosis who reported acute abdominal pain without fever or vomiting. At hospitalization all blood tests were within normal value. Abdominal ultrasounds showed an increase in spleen volume and a solid round-shaped hypoechogenic formation with hyperechogenic areas in the lower pole without vascolarisation on color-Doppler scan. These findings suggested torsion of the accessory spleen. We opted for a conservative approach: analgesics on demand and antibiotics. After a week symptoms resolved spontaneously and patient was discharged in good health conditions. Follow-up ultrasound scans were performed at one week, three-six months and one year after hospitalization and showed a progressive reduction of the dimensions of the solid round-shaped formation. Accessory spleen torsion needs to be added to the differential diagnosis of cases of acute abdomen in children. Ultrasounds with eco-color-Doppler scans seem to be the best option for the diagnosis of such condition in the pediatric age since other diagnostic methods are more invasive and require sedation of patients. Once accessory spleen torsion is correctly diagnosed it is possible to opt for its conservative treatment. PMID:24051978

  4. Torsionally-gravitating charged matter fields and quanta

    E-print Network

    Luca Fabbri

    2015-03-17

    In the present article we shall consider the torsional completion of a gravitational background that is filled with electrodynamically interacting material fields, taken to be of fermionic type, eventually deriving properties like the impossibility of singularities and the possibility of confinement, both necessary for a correct quantum description.

  5. 34. VERTICAL AND TORSIONAL MOTION VIEWED FROM EAST TOWER, 7 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    34. VERTICAL AND TORSIONAL MOTION VIEWED FROM EAST TOWER, 7 NOVEMBER 1940, FROM 16MN FILM SHOT BY PROFESSOR F.B. FARQUHARSON, UNIVERSITY OF WASHINGTON. (LABORATORY STUDIES ON THE TACOMA NARROWS BRIDGE, AT UNIVERSITY OF WASHINGTON (SEATTLE: UNIVERSITY OF WASHINGTON, DEPARTMENT OF CIVIL ENGINEERING, 1941) - Tacoma Narrows Bridge, Spanning Narrows at State Route 16, Tacoma, Pierce County, WA

  6. Torsional Oscillations and Waves Projected on the Wall

    ERIC Educational Resources Information Center

    Bartlett, Albert A.

    2008-01-01

    The article "Torsional Oscillations with Lorentz Force" by Paul Gluck provides a glimpse into the major world of ancient physics demonstrations in the late 19th and first half of the 20th centuries. The apparatus that was described and similar pieces of apparatus are the basis for many memorable but long forgotten educational demonstrations. The…

  7. Acute abdomen secondary to torsion of Krukenberg tumour.

    PubMed

    Bibi, Seema; Memon, Shaneela; Qazi, Roshan Ara

    2011-08-01

    Krukenberg tumour is a rare clinical entity. We report an unusual case of acute abdomen due to right sided adnexal torsion in a 23 year old nulliparous girl with bilateral Krukenberg tumour and primary gastric carcinoma. Possibility of Krukenberg tumour should always be kept in mind while managing ovarian tumours. PMID:22356011

  8. On Gravity, Torsion and the Spectral Action Principle

    E-print Network

    Frank Pfaeffle; Christoph A. Stephan

    2011-06-03

    We consider compact Riemannian spin manifolds without boundary equipped with orthogonal connections. We investigate the induced Dirac operators and the associated commutative spectral triples. In case of dimension four and totally anti-symmetric torsion we compute the Chamseddine-Connes spectral action, deduce the equations of motions and discuss critical points.

  9. Relativistic particles with rigidity and torsion in D = 3 spacetimes

    Microsoft Academic Search

    Manuel Barros; Angel Ferrández; Miguel Angel Javaloyes; Pascual Lucas

    2005-01-01

    Models describing relativistic particles, where Lagrangian densities depend linearly on both the curvature and the torsion of the trajectories, are revisited in D = 3 Lorentzian spacetimes with constant curvature. The moduli spaces of trajectories are completely and explicitly determined. Trajectories are Lancret curves including ordinary helices. To get the geometric integration of the solutions, we design algorithms that essentially

  10. The Torsional and Bending Deflection of Full-Scale Duralumin Propeller Blades under Normal Operating Conditions, Special Report

    NASA Technical Reports Server (NTRS)

    Hartman, Edwin P.; Biermann, David

    1938-01-01

    The torsional deflection of the blades of three full-scale duralumin propellers operating under various loading conditions was measured by a light-beam method. Angular bending deflections were also obtained as an incidental part of the study. The deflection measurements showed that the usual present-day type of propeller blades twisted but a negligible amount under ordinary flight conditions. A maximum deflection of about 1/10th of a degree was found at V/nD of 0.3 and a smaller deflection at higher values of V/nD for the station at 0.70 radius. These deflections are much smaller than would be expected from earlier tests, but the light-beam method is considered to be much more accurate than the direct-reading transit method used in the previous tests.

  11. The Torsional and Bending Deflection of Full-Scale Aluminum-Alloy Propeller Blades Under Normal Operating Conditions

    NASA Technical Reports Server (NTRS)

    Hartman, Edwin P; Biermann, David

    1938-01-01

    The torsional deflection of the blades of three full-scale aluminum-alloy propellers operating under various loading conditions was measured by a light-beam method. Angular bending deflections were also obtained as an incidental part of the study. The deflection measurements showed that the usual present-day type of propeller blades twisted but a negligible amount under ordinary flight conditions. A maximum deflection of about 1/10 degree was found at a v/nd of 0.3 and a smaller deflection at higher values of v/nd for the station at 0.70 radius. These deflections are much smaller than would be expected from earlier tests, but the light-beam method is considered to be much more accurate than the direct-reading-transit method used in the previous test.

  12. The Angular Momentum of Baryons and Dark Matter Halos Revisited

    NASA Technical Reports Server (NTRS)

    Kimm, Taysun; Devriendt, Julien; Slyz, Adrianne; Pichon, Christophe; Kassin, Susan A.; Dubois, Yohan

    2011-01-01

    Recent theoretical studies have shown that galaxies at high redshift are fed by cold, dense gas filaments, suggesting angular momentum transport by gas differs from that by dark matter. Revisiting this issue using high-resolution cosmological hydrodynamics simulations with adaptive-mesh refinement (AMR), we find that at the time of accretion, gas and dark matter do carry a similar amount of specific angular momentum, but that it is systematically higher than that of the dark matter halo as a whole. At high redshift, freshly accreted gas rapidly streams into the central region of the halo, directly depositing this large amount of angular momentum within a sphere of radius r = 0.1R(sub vir). In contrast, dark matter particles pass through the central region unscathed, and a fraction of them ends up populating the outer regions of the halo (r/R(sub vir) > 0.1), redistributing angular momentum in the process. As a result, large-scale motions of the cosmic web have to be considered as the origin of gas angular momentum rather than its virialised dark matter halo host. This generic result holds for halos of all masses at all redshifts, as radiative cooling ensures that a significant fraction of baryons remain trapped at the centre of the halos. Despite this injection of angular momentum enriched gas, we predict an amount for stellar discs which is in fair agreement with observations at z=0. This arises because the total specific angular momentum of the baryons (gas and stars) remains close to that of dark matter halos. Indeed, our simulations indicate that any differential loss of angular momentum amplitude between the two components is minor even though dark matter halos continuously lose between half and two-thirds of their specific angular momentum modulus as they evolve. In light of our results, a substantial revision of the standard theory of disc formation seems to be required. We propose a new scenario where gas efficiently carries the angular momentum generated by large-scale structure motions deep inside dark matter halos, redistributing it only in the vicinity of the disc.

  13. Aspects of gravity and supergravity theories

    SciTech Connect

    Velarde, G.G.

    1987-01-01

    The possible coupling of torsion and gauge fields is investigated within the context of five-dimensional Kaluza-Kelin theory and it is found that no such coupling arises for the vectorial part of torsion. It is shown that in Brans-Dicke-type models with torsion there is a conformal (Weyl) symmetry which allows for the possibility of transforming torsion away in the vacuum sector. It is also shown that maximally symmetric supergravity models are unable to solve the cosmological energy density (or Polonyi) problem. This problem is present in most models incorporating a weakly-coupled scalar field. Finally, working in the context of superstring-inspired models, it is proved that the gauge kinetic function is not renormalized by radiative corrections involving purely chiral superfields thus showing that no gaugino masses can arise by implementing this mechanism.

  14. Torsion Bounds from CP Violation ?2-DYNAMO in Axion-Photon Cosmic Plasma

    NASA Astrophysics Data System (ADS)

    Garcia de Andrade, L. C.

    Years ago Mohanty and Sarkar [Phys. Lett. B 433, 424 (1998)] have placed bounds on torsion mass from K meson physics. In this paper, associating torsion to axions a la Campanelli et al. [Phys. Rev. D 72, 123001 (2005)], it is shown that it is possible to place limits on spacetime torsion by considering an efficient ?2-dynamo CP violation term. Therefore instead of Kostelecky et al. [Phys. Rev. Lett. 100, 111102 (2008)] torsion bounds from Lorentz violation, here torsion bounds are obtained from CP violation through dynamo magnetic field amplification. It is also shown that oscillating photon-axion frequency peak is reduced to 10-7 Hz due to torsion mass (or Planck mass when torsion does not propagate) contribution to the photon-axion-torsion action. Though torsion does not couple to electromagnetic fields at classical level, it does at the quantum level. Recently, Garcia de Andrade [Phys. Lett. B 468, 28 (2011)] has shown that the photon sector of Lorentz violation (LV) Lagrangian leads to linear nonstandard Maxwell equations where the magnetic field decays slower giving rise to a seed for galactic dynamos. Torsion constraints of the order of K0?10-42 GeV can be obtained which are more stringent than the value obtained by Kostelecky et al. A lower bound for the existence of galactic dynamos is obtained for torsion as K0?10-37 GeV.

  15. Mesoscopic formulas of linear and angular momentum fluxes

    E-print Network

    Antoine Fruleux; Ken Sekimoto

    2014-07-26

    Cosserat theory [E. Cosserat and F. Cosserat, "Th\\'eorie des corps d\\'eformables" (Herman,1909)] is a way to extend a simple Newtonian fluid model or bulk elasticity models to incorporate the underlying mesoscopic structures into the macroscopic theory. However, this theory, which contains asymmetric stress tensor and "couple stress tensor", has been lacking its bottom-up theoretical basis which may correspond to the virial stress formula of Irving-Kirkwood theory of the gas hydrodynamics. Based on the momentum and angular momentum conservation laws, we will present a bottom-up formulation of the Cosserat-type theory in the way adapted to the dense cellular media. Mesoscopic formulas for the stress and couple stress tensors are given, which is reminiscent of the virial stress but without any assumptions about the interactions at the cell-cell interfaces.

  16. Coupling of cantilever lateral bending and torsion in torsional resonance and lateral excitation modes of atomic force microscopy

    Microsoft Academic Search

    Yaxin Song; Bharat Bhushan

    2006-01-01

    Torsional resonance (TR) mode and lateral excitation (LE) mode of atomic force microscopy (AFM) have been increasingly used in atomic and nanoscale surface imaging. In TR and LE modes, it is the changes of the cantilever dynamic characteristics caused by tip-sample interaction that reveal surface properties. For quantitative explanation of measured results, researchers have established dynamic models of TR and

  17. Study on torsional fretting wear behavior of a ball-on-socket contact configuration simulating an artificial cervical disk.

    PubMed

    Wang, Song; Wang, Fei; Liao, Zhenhua; Wang, Qingliang; Liu, Yuhong; Liu, Weiqiang

    2015-10-01

    A ball-on-socket contact configuration was designed to simulate an artificial cervical disk in structure. UHMWPE (ultra high molecular weight polyethylene) hot pressed by powders and Ti6Al4V alloy were selected as the material combination of ball and socket. The socket surface was coated by a ~500nm C-DLC (carbon ion implantation-diamond like carbon) mixed layer to improve its surface nano hardness and wear resistance. The torsional fretting wear behavior of the ball-on-socket model was tested at different angular displacements under 25% bovine serum lubrication with an axial force of 100N to obtain more realistic results with that in vivo. The fretting running regimes and wear damage characteristics as well as wear mechanisms for both ball and socket were studied based on 2D (two dimension) optical microscope, SEM (scanning electron microscope) and 3D (three dimension) profiles. With the increase of angular displacement amplitude from 1° to 7°, three types of T-? (Torsional torque-angular displacement amplitude) curves (i.e., linear, elliptical and parallelogram loops) corresponding to running regimes of PSR (partial slip regime), MR (mixed regime) and SR (slip regime) were observed and analyzed. Both the central region and the edge zone of the ball and socket were damaged. The worn surfaces were characterized by wear scratches and wear debris. In addition, more severe wear damage and more wear debris appeared on the central region of the socket at higher angular displacement amplitude. The dominant damage mechanism was a mix of surface scratch, adhesive wear and abrasive wear for the UHMWPE ball while that for the coated socket was abrasive wear by PE particles and some polishing and rolling process on the raised overgrown DLC grains. The frictional kinetic behavior, wear type, damage region and damage mechanism for the ball-on-socket model revealed significant differences with those of a ball-on-flat contact while showing better consistency with that of in vitro cervical prosthesis simulations according to the literature. PMID:26117735

  18. Uncertainty Relations for Angular Momentum

    E-print Network

    Lars Dammeier; Rene Schwonnek; Reinhard F. Werner

    2015-04-30

    In this work we study various notions of uncertainty for angular momentum in the spin-s representation of SU(2). We characterize the "uncertainty regions" given by all vectors, whose components are the variances of the three angular momentum components. A basic feature of this set is a lower bound for the sum of the three variances. We give a method for obtaining optimal lower bounds for uncertainty regions for general operator triples, and evaluate these for small s. Further lower bounds are derived by generalizing the technique by which Robertson obtained his state-dependent lower bound. These are optimal for large s, since they are saturated by states taken from the Holstein-Primakoff approximation. We show that, for all s, all variances are consistent with the so-called vector model, i.e., they can also be realized by a classical probability measure on a sphere of radius sqrt(s(s+1)). Entropic uncertainty relations can be discussed similarly, but are minimized by quite different states from the variance minimizing ones for small s. For large s the Maassen-Uffink bound becomes sharp, again being saturated by Holstein-Primakoff states. Measurement uncertainty, as recently discussed by Busch, Lahti and Werner for position and momentum, is introduced and a generalized observable (POVM) which minimizes the worst case measurement uncertainty of all angular momentum components is explicitly determined. Its outputs are angular momentum vectors whose absolute value r(s) depends only on s. The function r is determined explicitly, and r(s)/s approaches 1 from below.

  19. REMOVEALL BURRSAND SHARPEDGES ANGULAR TOL

    E-print Network

    Llope, William J.

    RHIC ± .02 ± .1 ± .005 .XX .X .XXX ± 1/ 2° ±1/ 64 REMOVEALL BURRSAND SHARPEDGES ANGULAR TOL MV2 MV3 Manual Valve PI1 PI2 PI3 Pressure Indicator (Dwyer 65030) Main Shutoff Valve (Asco EF8262G7) MSV1 gas pad PI4 PI5 PI6 FM1 FM2 FM3 Flowmeter (Teledyne HFC-202) Check Valve (Swagelok SS-4C-1/ 3) CV

  20. Paraxial Light Beams with Angular Momentum

    E-print Network

    A. Bekshaev; M. Soskin; M. Vasnetsov

    2008-01-15

    Fundamental and applied concepts concerning the ability of light beams to carry a certain mechanical angular momentum with respect to the propagation axis are reviewed and discussed. Following issues are included: Historical reference; Angular momentum of a paraxial beam and its constituents; Spin angular momentum and paradoxes associated with it; Orbital angular momentum; Circularly-spiral beams: examples and methods of generation; Orbital angular momentum and the intensity moments; Symmetry breakdown and decomposition of the orbital angular momentum; Mechanical models of the vortex light beams; Mechanical action of the beam angular momentum; Rotational Doppler effect, its manifestation in the image rotation; Spectrum of helical harmonics and associated problems; Non-collinear rotational Doppler effect; Properties of a beam forcedly rotating around its own axis. Research prospects and ways of practical utilization of optical beams with angular momentum.

  1. Achromatic orbital angular momentum generator

    NASA Astrophysics Data System (ADS)

    Bouchard, Frédéric; Mand, Harjaspreet; Mirhosseini, Mohammad; Karimi, Ebrahim; Boyd, Robert W.

    2014-12-01

    We describe a novel approach for generating light beams that carry orbital angular momentum (OAM) by means of total internal reflection in an isotropic medium. A continuous space-varying cylindrically symmetric reflector, in the form of two glued hollow axicons, is used to introduce a nonuniform rotation of polarization into a linearly polarized input beam. This device acts as a full spin-to-orbital angular momentum convertor. It functions by switching the helicity of the incoming beam?s polarization, and by conservation of total angular momentum thereby generates a well-defined value of OAM. Our device is broadband, since the phase shift due to total internal reflection is nearly independent of wavelength. We verify the broad-band behaviour by measuring the conversion efficiency of the device for three different wavelengths corresponding to the RGB colours, red, green and blue. An average conversion efficiency of 95% for these three different wavelengths is observed. This device may find applications in imaging from micro- to astronomical systems where a white vortex beam is needed.

  2. Texture Development During Equal Channel Angular Forging of BCC Metals

    SciTech Connect

    Agnew, S.R.

    1999-08-08

    Equal channel angular forging (ECAF) has been proposed as a severe plastic deformation technique for processing metals, alloys, and composites [e.g. Segal, 1995] (Fig. 1). The technique offers two capabilities of practical interest: a high degree of strain can be introduced with no change in the cross-sectional dimensions of the work-piece, hence, even greater strains can be introduced by re-inserting the work-piece for further deformation during subsequent passes through the ECAF die. Additionally, the deformation is accomplished by simple shear (like torsion of a short tube) on a plane whose orientation, with respect to prior deformations, can be controlled by varying the processing route. There is a nomenclature that has developed in the literature for the typical processing routes: A: no rotations; B{sub A}: 90 degrees CW (clockwise), 90 degrees CCW (counterclockwise), 9O degrees CW, 90 degrees CCW...; Bc: 90 degrees CW, 90 degrees CW, 90 degrees CW...; and C: 180 degrees, 18 0 degrees.... The impact of processing route on the subsequent microstructure [Ferasse, Segal, Hartwig and Goforth, 1997; Iwahashi, Horita, Nemoto and Langdon, 1996] and texture [Gibbs, Hartwig, Cornwell, Goforth and Payzant, 1998] has been the subject of numerous experimental studies.

  3. Inter-Ring and Hexyl Chain Torsional Potentials in Poly (3-HEXYLTHIOPHENE) Oligomers: Scaling with the Length of the Conjugted Polymer Backbone

    NASA Astrophysics Data System (ADS)

    Bhatta, Ram S.; Perry, David S.; Yimer, Yeneneh; Tsige, Mesfin

    2011-06-01

    Density functional theory calculations are presented for the equilibrium structures and torsional potentials for isolated Poly (3-Hexylthiophene) (P3HT) oligomers up to 12 monomer units (up to 302 atoms). Calculations were performed at B3LYP/6-31++G(d,p) treating both the backbone of thiophene rings and the hexyl chains explicitly. One-dimensional inter-ring torsional potentials were calculated by rotating backbone around the central inter-ring bond and hexyl torsional potentials were calculated rotating n-hexyl group adjacent to the central inter-ring bond for each oligomer. The torsional and electronic properties change significantly for oligomers with 2 to 8 units but reach asymptotic values for a 10 unit P3HT chain, thereby suggesting the 10 unit long oligomer as a molecular model for the extended polymer. For P3HT oligomers having 10 or more units, all the rings and the hexyl groups are approximately coplanar except for one hexyl group at head end. The principal interaction that promotes the coplanarity of the hexyl groups is the attraction of the proximal methylene hydrogens to the sulfur on the adjacent thiophene ring. The cis conformation of the backbone is about 2kT higher than the trans minimum at room temperature. The gauche conformation of the hexyl group is within about half kT of the planar minimum. Therefore conformational polymorphisms of both types will likely be significant in the heterogeneous environment of photovoltaic devices.

  4. On a finite-state inflow application to flap-lag-torsion damping in hover

    NASA Technical Reports Server (NTRS)

    De Andrade, Donizeti; Peters, David A.

    1992-01-01

    An aerodynamic model with a coupled set of generalized dynamic wake equations and hybrid equations of motion for an elastic blade are applied here to a two-blade untwisted stiff in-plane hingeless small-scale model rotor with torsionally soft blades. Blade root offset, precone, blade droop, pitch control stiffness, and blade pitch angle are included in the model rotor. Numerical results show that 3D tip relief effects within the nonuniform steady-state inflow are significant to predict steady-state aerodynamic loads and blade deflections. Eigenvalue results confirm the importance of unsteady 3D aerodynamics in predicting lead-lag damping and frequency. Eigenvector analysis correlations reinforced qualitative and quantitative shortcomings associated with quasi-steady 2D aerodynamic theory for aeroelastic applications in hover.

  5. The transition to Earth-like torsional oscillations in magnetoconvection simulations

    NASA Astrophysics Data System (ADS)

    Teed, Robert J.; Jones, Chris A.; Tobias, Steven M.

    2015-06-01

    Evidence for torsional oscillations (TOs) operating within the Earth's fluid outer core has been found in the secular variation of the geomagnetic field. These waves arise via disturbances to the predominant (magnetostrophic) force balance believed to exist in the core. The coupling of the core and mantle allow TOs to affect the length-of-day of the Earth via angular momentum conservation. Encouraged by previous work, where we were able to observe TOs in geodynamo simulations, we perform 3-D magnetoconvection simulations in a spherical shell in order to reach more Earth-like parameter regimes that proved hitherto elusive. At large Ekman numbers we find that TOs can be present but are typically only a small fraction of the overall dynamics and are often driven by Reynolds forcing at various locations throughout the domain. However, as the Ekman number is reduced to more Earth-like values, TOs become more apparent and can make up the dominant portion of the short timescale flow. This coincides with a transition to regimes where excitation is found only at the tangent cylinder, is delivered by the Lorentz force and gives rise to a periodic Earth-like wave pattern, approximately operating on a 4 to 5 year timescale. The core travel times of our waves also become independent of rotation at low Ekman number with many converging to Earth-like values of around 4 years.

  6. Angular Momentum Transport in Astrophysical Accretion Flows

    E-print Network

    Hammett, Greg

    Angular Momentum Transport in Astrophysical Accretion Flows Greg Hammett, Princeton Plasma Physics of matter onto a central object (generally w/ angular momentum) · Central to ­ Star & Planet Formation to Sgr A* #12;Outline · Accretion Disks: Basic Physical Picture · MHD of Disks: Angular Momentum

  7. Angular Momentum Decomposition for an Electron

    E-print Network

    Matthias Burkardt; Hikmat BC

    2008-12-09

    We calculate the orbital angular momentum of the `quark' in the scalar diquark model as well as that of the electron in QED (to order $\\alpha$). We compare the orbital angular momentum obtained from the Jaffe-Manohar decomposition to that obtained from the Ji relation and estimate the importance of the vector potential in the definition of orbital angular momentum.

  8. Angular Momentum Decomposition for an Electron

    SciTech Connect

    Burkardt, Matthias; BC, Hikmat

    2009-01-01

    We calculate the orbital angular momentum of the `quark' in the scalar diquark model as well as that of the electron in QED (to order $\\alpha$). We compare the orbital angular momentum obtained from the Jaffe-Manohar decomposition to that obtained from the Ji relation and estimate the importance of the vector potential in the definition of orbital angular momentum.

  9. Generalised models for torsional spine and fan magnetic reconnection

    NASA Astrophysics Data System (ADS)

    Pontin, D. I.; Al-Hachami, A. K.; Galsgaard, K.

    2011-09-01

    Context. Three-dimensional (3D) null points are present in abundance in the solar corona, and the same is likely to be true in other astrophysical environments. Recent results from solar observations and from simulations suggest that reconnection at such 3D nulls may play an important role in the coronal dynamics. Aims: The properties of the torsional spine and torsional fan modes of magnetic reconnection at 3D nulls are investigated. New analytical models are developed, which for the first time include a current layer that is spatially localised around the null, extending along either the spine or the fan of the null. The principal aim is to investigate the effect of varying the degree of asymmetry of the null point magnetic field on the resulting reconnection process - where previous studies always considered a non-generic radially symmetric null. Methods: Analytical solutions are derived for the steady kinematic equations, and are compared with the results of numerical simulations in which the full set of resistive MHD equations is solved. Results: The geometry of the current layers within which torsional spine and torsional fan reconnection occur is strongly dependent on the symmetry of the magnetic field. Torsional spine reconnection occurs in a narrow tube around the spine, with elliptical cross-section when the fan eigenvalues are different. The eccentricity of the ellipse increases as the degree of asymmetry increases, with the short axis of the ellipse being along the strong field direction. The spatiotemporal peak current, and the peak reconnection rate attained, are found not to depend strongly on the degree of asymmetry. For torsional fan reconnection, the reconnection occurs in a planar disk in the fan surface, which is again elliptical when the symmetry of the magnetic field is broken. The short axis of the ellipse is along the weak field direction, with the current being peaked in these weak field regions. The peak current and peak reconnection rate in this case are clearly dependent on the asymmetry, with the peak current increasing but the reconnection rate decreasing as the degree of asymmetry is increased.

  10. Angular momentum and torque described with the complex octonion

    E-print Network

    Weng, Zi-Hua

    2015-01-01

    The paper aims to adopt the complex octonion to formulate the angular momentum, torque, and force etc in the electromagnetic and gravitational fields. Applying the octonionic representation enables one single definition of angular momentum (or torque, force) to combine some physics contents, which were considered to be independent of each other in the past. J. C. Maxwell used simultaneously two methods, the vector terminology and quaternion analysis, to depict the electromagnetic theory. It motivates the paper to introduce the quaternion space into the field theory, describing the physical feature of electromagnetic and gravitational fields. The spaces of two fields can be chosen as the quaternion spaces, while the coordinate component of quaternion space is able to be the complex number. The quaternion space of electromagnetic field is independent of that of gravitational field. These two quaternion spaces may compose one octonion space. Contrarily, one octonion space can be separated into two subspaces, the...

  11. Accelerated rotation with orbital angular momentum modes

    NASA Astrophysics Data System (ADS)

    Schulze, Christian; Roux, Filippus S.; Dudley, Angela; Rop, Ronald; Duparré, Michael; Forbes, Andrew

    2015-04-01

    We introduce a class of light field that angularly accelerates during propagation. We show that the acceleration (deceleration) may be controlled by adjustment of a single parameter, and tuned continuously, down to no acceleration at all. As the angular acceleration takes place in a bounded space, the azimuthal degree of freedom, such fields accelerate periodically as they propagate. Notably, the amount of angular acceleration is not limited by paraxial considerations, may be tailored for large accelerations over arbitrarily long distances, and can be engineered independently of the beam's spatial extent. We discuss how such angularly accelerating light fields can maintain the conservation of angular momentum through an energy exchange mechanism across the field.

  12. Angular Synchronization by Eigenvectors and Semidefinite Programming

    PubMed Central

    Singer, A.

    2010-01-01

    The angular synchronization problem is to obtain an accurate estimation (up to a constant additive phase) for a set of unknown angles ?1, …, ?n from m noisy measurements of their offsets ?i ? ?j mod 2?. Of particular interest is angle recovery in the presence of many outlier measurements that are uniformly distributed in [0, 2?) and carry no information on the true offsets. We introduce an efficient recovery algorithm for the unknown angles from the top eigenvector of a specially designed Hermitian matrix. The eigenvector method is extremely stable and succeeds even when the number of outliers is exceedingly large. For example, we successfully estimate n = 400 angles from a full set of m=(4002) offset measurements of which 90% are outliers in less than a second on a commercial laptop. The performance of the method is analyzed using random matrix theory and information theory. We discuss the relation of the synchronization problem to the combinatorial optimization problem Max-2-Lin mod L and present a semidefinite relaxation for angle recovery, drawing similarities with the Goemans-Williamson algorithm for finding the maximum cut in a weighted graph. We present extensions of the eigenvector method to other synchronization problems that involve different group structures and their applications, such as the time synchronization problem in distributed networks and the surface reconstruction problems in computer vision and optics. PMID:21179593

  13. State reversals of optically induced tilt and torsional eye movements

    NASA Technical Reports Server (NTRS)

    Finke, R. A.; Held, R.

    1978-01-01

    Alternations of the state of apparent self-motion during observation of a large visual display rotating about the line of sight are associated with alternations in the magnitude of induced tilt and torsional eye rotation. In one experiment, shifts in visually induced tilt during these state alternations are found to be in the opposite direction to corresponding shifts in induced ocular torsion. In a second experiment, the reversals of self-motion perception are shown to be an intravisual phenomenon, independent of competing inputs provided by the vestibular system. These results emphasize the importance of distinguishing between visual and vestibular processes in tilt perception and ocular rotation during human orientation to gravitational vertical.

  14. Structural plasticity of single chromatin fibers revealed by torsional manipulation

    E-print Network

    Aurelien Bancaud; Natalia Conde e Silva; Maria Barbi; Gaudeline Wagner; Jean-Francois Allemand; Julien Mozziconacci; Christophe Lavelle; Vincent Croquette; Jean-Marc Victor; Ariel Prunell; Jean-Louis Viovy

    2007-07-13

    Magnetic tweezers are used to study the mechanical response under torsion of single nucleosome arrays reconstituted on tandem repeats of 5S positioning sequences. Regular arrays are extremely resilient and can reversibly accommodate a large amount of supercoiling without much change in length. This behavior is quantitatively described by a molecular model of the chromatin 3-D architecture. In this model, we assume the existence of a dynamic equilibrium between three conformations of the nucleosome, which are determined by the crossing status of the entry/exit DNAs (positive, null or negative). Torsional strain, in displacing that equilibrium, extensively reorganizes the fiber architecture. The model explains a number of long-standing topological questions regarding DNA in chromatin, and may provide the ground to better understand the dynamic binding of most chromatin-associated proteins.

  15. Bending and Torsion Load Alleviator With Automatic Reset

    NASA Technical Reports Server (NTRS)

    delaFuente, Horacio M. (Inventor); Eubanks, Michael C. (Inventor); Dao, Anthony X. (Inventor)

    1996-01-01

    A force transmitting load alleviator apparatus and method are provided for rotatably and pivotally driving a member to be protected against overload torsional and bending (moment) forces. The load alleviator includes at least one bias spring to resiliently bias cam followers and cam surfaces together and to maintain them in locked engagement unless a predetermined load is exceeded whereupon a center housing is pivotal or rotational with respect to a crown assembly. This pivotal and rotational movement results in frictional dissipation of the overload force by an energy dissipator. The energy dissipator can be provided to dissipate substantially more energy from the overload force than from the bias force that automatically resets the center housing and crown assembly to the normally fixed centered alignment. The torsional and bending (moment) overload levels can designed independently of each other.

  16. Dark energy fifth forces in torsion pendulum experiments

    E-print Network

    Amol Upadhye

    2012-10-22

    The chameleon scalar field is a matter-coupled dark energy candidate whose nonlinear self-interaction partially screens its fifth force at laboratory scales. Nevertheless, small-scale experiments such as the torsion pendulum can provide powerful constraints on chameleon models. Here we develop a simple approximation for computing chameleon fifth forces in torsion pendulum experiments such as Eot-Wash. We show that our approximation agrees well with published constraints on the quartic chameleon, and we use it to extend these constraints to a much wider range of models. Finally, we forecast the constraints which will result from the next-generation Eot-Wash experiment, and show that this experiment will exclude a wide range of quantum-stable models.

  17. MAGNETOSEISMOLOGY: EIGENMODES OF TORSIONAL ALFVEN WAVES IN STRATIFIED SOLAR WAVEGUIDES

    SciTech Connect

    Verth, G.; Goossens, M. [Centrum voor Plasma Astrofysica, KU Leuven, Celestijnenlaan 200B, 3001 Heverlee (Belgium); Erdelyi, R., E-mail: Gary.Verth@wis.kuleuven.b, E-mail: Marcel.Goossens@wis.kuleuven.b, E-mail: robertus@sheffield.ac.u [Solar Physics and Space Plasma Research Centre (SP2RC), University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

    2010-05-10

    There have recently been significant claims of Alfven wave observation in the solar chromosphere and corona. We investigate how the radial and longitudinal plasma structuring affects the observational properties of torsional Alfven waves in magnetic flux tubes for the purposes of solar magnetoseismology. The governing magnetohydrodynamic equations of these waves in axisymmetric flux tubes of arbitrary radial and axial plasma structuring are derived and we study their observable properties for various equilibria in both thin and finite-width magnetic flux tubes. For thin flux tubes, it is demonstrated that observation of the eigenmodes of torsional Alfven waves can provide temperature diagnostics of both the internal and surrounding plasma. In the finite-width flux tube regime, it is shown that these waves are the ideal magnetoseismological tool for probing radial plasma inhomogeneity in solar waveguides.

  18. Torsion, Parity-odd Response and Anomalies in Topological States

    E-print Network

    Onkar Parrikar; Taylor L. Hughes; Robert G. Leigh

    2014-07-25

    We study the response of a class of topological systems to electromagnetic and gravitational sources, including torsion and curvature. By using the technology of anomaly polynomials, we derive the parity-odd response of a massive Dirac fermion in $d=2+1$ and $d=4+1$, which provides a simple model for a topological insulator. We discuss the covariant anomalies of the corresponding edge states, from a Callan-Harvey anomaly-inflow, as well as a Hamiltonian spectral flow point of view. We also discuss the applicability of our results to other systems such as Weyl semi-metals. Finally, using dimensional reduction from $d=4+1$, we derive the effective action for a $d=3+1$ time-reversal invariant topological insulator in the presence of torsion and curvature, and discuss its various physical consequences.

  19. Ultrahigh torsional stiffness and strength of boron nitride nanotubes.

    PubMed

    Garel, Jonathan; Leven, Itai; Zhi, Chunyi; Nagapriya, K S; Popovitz-Biro, Ronit; Golberg, Dmitri; Bando, Yoshio; Hod, Oded; Joselevich, Ernesto

    2012-12-12

    We report the experimental and theoretical study of boron nitride nanotube (BNNT) torsional mechanics. We show that BNNTs exhibit a much stronger mechanical interlayer coupling than carbon nanotubes (CNTs). This feature makes BNNTs up to 1 order of magnitude stiffer and stronger than CNTs. We attribute this interlayer locking to the faceted nature of BNNTs, arising from the polarity of the B-N bond. This property makes BNNTs superior candidates to replace CNTs in nanoelectromechanical systems (NEMS), fibers, and nanocomposites. PMID:23130892

  20. Calibration of combined bending-torsion fatigue reliability data reduction

    NASA Technical Reports Server (NTRS)

    Kececioglu, D.; Mcconnell, J. B.

    1969-01-01

    The combined bending-torsion fatigue reliability research machines are described. Three such machines are presently in operation. The calibration of these machines is presented in depth. Fatigue data generated with these machines for SAE 4340 steel grooved specimens subjected to reversed bending and steady torque loading are given. The data reduction procedure is presented. Finally, some comments are made about notch sensitivity and stress concentration as applied to combined fatigue.

  1. Improved Torsion Pendulum for Ground Testing of LISA Displacement Sensors

    E-print Network

    L. Carbone; A. Cavalleri; R. Dolesi; C. D. Hoyle; M. Hueller; S. Vitale; W. J. Weber

    2004-11-09

    We discuss a new torsion pendulum design for ground testing of prototype LISA (Laser Interferometer Space Antenna) displacement sensors. This new design is directly sensitive to net forces and therefore provides a more representative test of the noisy forces and parasitic stiffnesses acting on the test mass as compared to previous ground-based experiments. We also discuss a specific application to the measurement of thermal gradient effects.

  2. The initial torsional stiffness of shells with interior webs

    NASA Technical Reports Server (NTRS)

    Kuhn, Paul

    1935-01-01

    A method of calculating the stresses and torsional stiffness of thin shells with interior webs is summarized. Comparisons between experimental and calculated results are given for 3 duralumin beams, 5 stainless steel beams and 2 duralumin wings. It is concluded that if the theoretical stiffness is multiplied by a correction factor of 0.9, experimental values may be expected to check calculated values within about 10 percent.

  3. Torsion-balance tests of the weak equivalence principle

    E-print Network

    T. A. Wagner; S. Schlamminger; J. H. Gundlach; E. G. Adelberger

    2012-07-10

    We briefly summarize motivations for testing the weak equivalence principle and then review recent torsion-balance results that compare the differential accelerations of beryllium-aluminum and beryllium-titanium test body pairs with precisions at the part in $10^{13}$ level. We discuss some implications of these results for the gravitational properties of antimatter and dark matter, and speculate about the prospects for further improvements in experimental sensitivity.

  4. Genetic and clinical features of primary torsion dystonia

    PubMed Central

    Ozelius, Laurie J.; Bressman, Susan B.

    2011-01-01

    Primary torsion dystonia (PTD) is defined as a syndrome in which dystonia is the only clinical sign (except for tremor), and there is no evidence of neuronal degeneration or an acquired cause by history or routine laboratory assessment. Seven different loci have been recognized for PTD but only two of the genes have been identified. In this review we will described the phenotypes associated with these loci and discuss the responsible gene. PMID:21168499

  5. A modified torsional kolsky bar for investigating dynamic friction

    Microsoft Academic Search

    S. Rajagopalan; V. Prakash

    1999-01-01

    This paper introduces an experiment to investigate dry sliding resistance of frictional interfaces at normal pressures up\\u000a to 100 MPa, slip speeds up to 10 m\\/s and slip distances of approximately 10 mm. This new apparatus involves a novel modification\\u000a of the conventional torsional Kolsky bar apparatus, employed extensively in the past for investigating high strain rate behavior\\u000a of engineering

  6. Simple currents versus orbifolds with discrete torsion - a complete classification

    Microsoft Academic Search

    M. Kreuzer; A. N. Schellekens

    1994-01-01

    We give a complete classification of all simple current modular invariants, extending previous results for (Zp)k to arbitrary centers. We obtain a simple explicit formula for the most general case. Using orbifold techniques to this end, we find a one-to-one correspondence between simple current invariants and subgroups of the center with discrete torsions. As a by-product, we prove the conjectured

  7. Observation of 1990 solar eclipse by a torsion pendulum

    SciTech Connect

    Luo Jun; Li Jianguo; Zhang Xuerong (Huazhong University of Science and Technology, Wuhan (China)); Liakhovets, V. (Patrice Lumumba Peoples Friendship University, Moscow (U.S.S.R.)); Lomonosov, M.; Ragyn, A. (Krasnopresnenskaya Observatory, Sternberg Astronomical Institute, Moscow (U.S.S.R.))

    1991-10-15

    During the solar eclipse of 22 July 1990 in the city of Bielomorsk of the U.S.S.R., we repeated the torsion pendulum experiment of Saxl and Allen, who reported an anomalous period increase during the solar eclipse of 7 March 1970. The relative change in the pendulum's period associated with the eclipse was found to be less than 5.2{times}10{sup {minus}5} (90% confidence).

  8. Preimplantation genetic diagnosis for early-onset torsion dystonia

    Microsoft Academic Search

    S Rechitsky; O Verlinsky; A Kuliev; S Ozen; K Laziuk; R Beck; N Gleicher; Y Verlinsky

    2004-01-01

    Early-onset primary torsion dystonia (DYT1) is the most severe and common form of hereditary movement disorders, characterized by sustained twisting contractures that begin in childhood, which is caused in majority of cases by a 3-bp deletion of the DYT1 gene on chromosome 9q34 at the heterozygote state. As there is no effective treatment of this disease, preimplantation genetic diagnosis (PGD)

  9. Torsion-balance tests of the weak equivalence principle

    E-print Network

    Wagner, T A; Gundlach, J H; Adelberger, E G

    2012-01-01

    We briefly summarize motivations for testing the weak equivalence principle and then review recent torsion-balance results that compare the differential accelerations of beryllium-aluminum and beryllium-titanium test body pairs with precisions at the part in $10^{13}$ level. We discuss some implications of these results for the gravitational properties of antimatter and dark matter, and speculate about the prospects for further improvements in experimental sensitivity.

  10. Torsion-balance tests of the weak equivalence principle

    Microsoft Academic Search

    T A Wagner; S Schlamminger; J H Gundlach; E G Adelberger

    2012-01-01

    We briefly summarize motivations for testing the weak equivalence principle and then review recent torsion-balance results that compare the differential accelerations of beryllium–aluminum and beryllium–titanium test-body pairs with precisions at the part in 1013 level. We discuss some implications of these results for the gravitational properties of antimatter and dark matter and speculate about the prospects for further improvements in

  11. Two-axis angular effector

    DOEpatents

    Vaughn, Mark R. (Albuquerque, NM); Robinett, III, Rush D. (Tijeras, NM); Phelan, John R. (Albuquerque, NM); Van Zuiden, Don M. (Albuquerque, NM)

    1997-01-21

    A new class of coplanar two-axis angular effectors. These effectors combine a two-axis rotational joint analogous to a Cardan joint with linear actuators in a manner to produce a wider range of rotational motion about both axes defined by the joint. This new class of effectors also allows design of robotic manipulators having very high strength and efficiency. These effectors are particularly suited for remote operation in unknown surroundings, because of their extraordinary versatility. An immediate application is to the problems which arise in nuclear waste remediation.

  12. Variable Distance Angular Symbology Reader

    NASA Technical Reports Server (NTRS)

    Schramm, Harry F., Jr. (Inventor); Corder, Eric L. (Inventor)

    2006-01-01

    A variable distance angular symbology, reader utilizes at least one light source to direct light through a beam splitter and onto a target. A target may be angled relative to the impinging light beam up to and maybe even greater than 45deg. A reflected beam from the target passes through the beam splitter and is preferably directed 90deg relative to the light source through a telecentric lens to a scanner which records an image of the target such as a direct part marking code.

  13. BCN nanotubes as highly sensitive torsional electromechanical transducers.

    PubMed

    Garel, Jonathan; Zhao, Chong; Popovitz-Biro, Ronit; Golberg, Dmitri; Wang, Wenlong; Joselevich, Ernesto

    2014-11-12

    Owing to their mechanically tunable electronic properties, carbon nanotubes (CNTs) have been widely studied as potential components for nanoelectromechanical systems (NEMS); however, the mechanical properties of multiwall CNTs are often limited by the weak shear interactions between the graphitic layers. Boron nitride nanotubes (BNNTs) exhibit a strong interlayer mechanical coupling, but their high electrical resistance limits their use as electromechanical transducers. Can the outstanding mechanical properties of BNNTs be combined with the electromechanical properties of CNTs in one hybrid structure? Here, we report the first experimental study of boron carbonitride nanotube (BCNNT) mechanics and electromechanics. We found that the hybrid BCNNTs are up to five times torsionally stiffer and stronger than CNTs, thereby retaining to a large extent the ultrahigh torsional stiffness of BNNTs. At the same time, we show that the electrical response of BCNNTs to torsion is 1 to 2 orders of magnitude higher than that of CNTs. These results demonstrate that BCNNTs could be especially attractive building blocks for NEMS. PMID:25275220

  14. Characterizing conformation changes in proteins through the torsional elastic response.

    PubMed

    Dos Santos, Helena G; Klett, Javier; Méndez, Raúl; Bastolla, Ugo

    2013-05-01

    The relationship between functional conformation changes and thermal dynamics of proteins is investigated with the help of the torsional network model (TNM), an elastic network model in torsion angle space that we recently introduced. We propose and test a null-model of "random" conformation changes that assumes that the contributions of normal modes to conformation changes are proportional to their contributions to thermal fluctuations. Deviations from this null model are generally small. When they are large and significant, they consist in conformation changes that are represented by very few low frequency normal modes and overcome small energy barriers. We interpret these features as the result of natural selection favoring the intrinsic protein dynamics consistent with functional conformation changes. These "selected" conformation changes are more frequently associated to ligand binding, and in particular phosphorylation, than to pairs of conformations with the same ligands. This deep relationship between the thermal dynamics of a protein, represented by its normal modes, and its functional dynamics can reconcile in a unique framework the two models of conformation changes, conformational selection and induced fit. The program TNM that computes torsional normal modes and analyzes conformation changes is available upon request. This article is part of a Special Issue entitled: The emerging dynamic view of proteins: Protein plasticity in allostery, evolution and self-assembly. PMID:23429178

  15. Development of a torsion balance for adhesion measurements

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Maeda, Chikayoshi; Masuo, Ryuichi

    1988-01-01

    A new torsion balance for study of adhesion in ceramics is discussed. A torsion wire and a linear variable differential transformer are used to monitor load and to measure pull-off force (adhesion force). The investigation suggests that this torsion balance is valuable in studying the interfacial properties of ceramics in controlled environments such as in ultrahigh vacuum. The pull-off forces measured in dry, moist, and saturated nitrogen atmosphere demonstrate that the adhesion of silicon nitride contacts remains low at humidities below 80 percent but rises rapidly above that. The adhesion at saturation is 10 times or more greater than that below 80 percent relative humidity. The adhesion in a saturated atmosphere arises primarily from the surface tension effects of a thin film of water adsorbed on the surface. The surface tension of the water film was 58 x 10 to the minus 5 to 65 x 10 to the minus 5 power. The accepted value for water is 72.7 x 10 to the minus 5 power N/cm. Adhesion characteristics of silicon nitride in contact with metals, like the friction characteristics of silicon carbide to metal contacts, can be related to the relative chemical activity of metals in ultrahigh vacuum. The more active the metal, the higher the adhesion.

  16. Preimplantation genetic diagnosis for early-onset torsion dystonia.

    PubMed

    Rechitsky, S; Verlinsky, O; Kuliev, A; Ozen, S; Laziuk, K; Beck, R; Gleicher, N; Verlinsky, Y

    2004-02-01

    Early-onset primary torsion dystonia (DYT1) is the most severe and common form of hereditary movement disorders, characterized by sustained twisting contractures that begin in childhood, which is caused in majority of cases by a 3-bp deletion of the DYT1 gene on chromosome 9q34 at the heterozygote state. As there is no effective treatment of this disease, preimplantation genetic diagnosis (PGD) may be a useful option for at-risk couples to establish an DYT1 mutation-free pregnancy. PGD was performed for two obligate carriers of the DYT1 3-bp deletion, using blastomere testing to preselect the mutation-free embryos, based on mutation analysis with simultaneous testing of the three closely linked markers, D9S62, D9S63 and ASS. Of 19 tested blastomeres in three cycles, 17 had conclusive information about the mutation and linked markers, of which eight were predicted to be free of 3-bp deletion. Six of these embryos were transferred back to patients, two in each cycle, yielding singleton DYT1 3-bp deletion-free clinical pregnancies in two. One of these pregnancies was terminated due to severe anencephaly and the other resulted in birth of a mutation-free child. This is the first PGD for primary torsion dystonia, providing an alternative for those at-risk couples who cannot accept prenatal diagnosis and termination of pregnancy as an option for avoiding early onset torsion dystonia. PMID:14989804

  17. Improving the sensitivity of a torsion pendulum by using an optical spring method

    SciTech Connect

    Wang Qinglan; Yeh Hsienchi; Zhou Zebing; Luo Jun [Department of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2009-10-15

    We present a scheme aiming at improving the sensitivity of a torsion pendulum by means of radiation-pressure-induced optical spring. Two partial-reflective mirrors are installed on the opposite sides of a torsion pendulum, and one high-reflective mirror is mounted at the end of the torsion beam so that two identical Fabry-Perot cavities can be formed and aligned in series. Due to the antisymmetric radiation pressures acting on the opposite sides of the torsion beam, a negative restoring coefficient can be generated within a certain dynamic range, such that both the resultant torsional rigidity and the resonant frequency of the torsion pendulum are reduced, and the minimum detectable response torque in high-frequency region can be reduced accordingly.

  18. Integrability Conditions for Killing-Yano Tensors and Maximally Symmetric Spaces in the Presence of Torsion

    E-print Network

    Batista, Carlos

    2015-01-01

    The integrability conditions for the existence of Killing-Yano tensors or, equivalently, covariantly closed conformal Killing-Yano tensors, in the presence of torsion are worked out. As an application, all metrics and torsions compatible with the existence of a Killing-Yano tensor of order n-1 are obtained. Finally, the issue of defining a maximally symmetric space with respect to connections with torsion is addressed.

  19. Extended torsional tests of an interlocked bi-stem satellite boom

    NASA Technical Reports Server (NTRS)

    Abercrombie, R. A.

    1973-01-01

    The effect is reported of continued oscillations of a 1.27-cm interlocked bi-stem satellite boom. The test setup oscillated a boom continuously between set torque limits and periodically recorded its hysteresis characteristics. Results showed that repeated oscillations affected torsional characteristics and that torsional rigidity changed as a function of the number of cycles oscillated within certain torque limits. Torsional characteristics changes caused by repeated oscillations were retained.

  20. Ptolemy diagrams and torsion pairs in the cluster category of Dynkin type A_n

    E-print Network

    Holm, Thorsten; Rubey, Martin

    2010-01-01

    We give a complete classification of torsion pairs in the cluster category of Dynkin type A_n. Along the way we give a new combinatorial description of Ptolemy diagrams, an infinite version of which was introduced by Ng. This allows us to count the number of torsion pairs in the cluster category of type A_n. We also count torsion pairs up to Auslander-Reiten translation.

  1. Eye torsion and visual tilt are mediated by different binocular processes

    NASA Technical Reports Server (NTRS)

    Wolfe, J. M.; Held, R.

    1979-01-01

    Viewing a large, patterned field rotating about the line of sight produces two measurable effects; cyclotorsion of the eyes (torsion) and a perceived displacement of vertical and horizontal (tilt). Experiments examining binocular interaction for these effects show: (1) both effects demonstrate summation in normal individuals and thus both involve a binocular process; (2) the process for tilt is different than for torsion, since summation for torsion is spared in stereodeficient individuals while that for tilt is eliminated.

  2. Free-space fiber-optic switches based on MEMS vertical torsion mirrors

    Microsoft Academic Search

    Shi-Sheng Lee; Long-Sun Huang; Chang-Jin Kim; Ming C. Wu

    1999-01-01

    This paper reports on the design, fabrication, and performance of a novel MEMS (micro-electro-mechanical-system) fiber-optic switch based on surface-micromachined vertical torsion mirrors. The vertical torsion mirror itself can be used as a 1×2 or an ON-OFF switch. A 2×2 MEMS fiber-optic switch with four vertical torsion mirrors has also been fabricated. The switching voltage is measured to be 80 V

  3. Torsional strengthening of rectangular and flanged beams using carbon fibre-reinforced-polymers – Experimental study

    Microsoft Academic Search

    Constantin E. Chalioris

    2008-01-01

    The present experimental investigation deals with the torsional strengthening of concrete beams without stirrups using epoxy-bonded carbon fibre-reinforced-polymer (FRP) sheets and strips as external transverse reinforcement. The experimental program comprises 14 rectangular and T-shaped beams tested under pure torsion. Based on the measured values of the torsional moment at cracking and at ultimate, the corresponding twists, the behavioural curves and

  4. On The Torsional Oscillations In Babcock-Leighton Solar Dynamo Models

    NASA Astrophysics Data System (ADS)

    Durney, Bernard R.

    2000-09-01

    The torsional oscillations at the solar surface have been interpreted by Schüssler and Yoshimura as being generated by the Lorentz force associated with the solar dynamo. It has been shown recently that they are also present in the upper half of the solar convection zone (SCZ). With the help of a solar dynamo model of the Babcock-Leighton type studied earlier, the longitudinal component of the Lorentz force, L_?, is calculated, and its sign or isocontours, are plotted vs. time, t, and polar angle, ? (the horizontal and vertical axis respectively). Two cases are considered, (1) differential rotation differs from zero only in the tachocline, (2) differential rotation as in (1) in the tachocline, and purely latitudinal and independent of depth in the bulk of the SCZ. In the first case the sign of L_? is roughly independent of latitude (corresponding to vertical bands in the t,? plot), whereas in the second case the bands show a pole-equator slope of the correct sign. The pattern of the bands still differs, however, considerably from that of the helioseismic observations, and the values of the Lorentz force are too small at low latitudes. It is all but certain that the toroidal field that lies at the origin of the large bipolar magnetic regions observed at the surface, must be generated in the tachocline by differential rotation; the regeneration of the corresponding poloidal field, B_p has not yet been fully clarified. B_p could be regenerated, for example, at the surface (as in Babcock-Leighton models), or slightly above the tachocline, (as in interface dynamos). In the framework of the Babcock-Leighton models, the following scenario is suggested: the dynamo processes that give rise to the large bipolar magnetic regions are only part of the cyclic solar dynamo (to distinguish it from the turbulent dynamo). The toroidal field generated locally by differential rotation must contribute significantly to the torsional oscillations patterns. As this field becomes buoyant, it should give rise, at the surface, to the smaller bipolar magnetic regions as, e.g., to the ephemeral bipolar magnetic regions. These have a weak non-random orientation of magnetic axis, and must therefore also contribute to the source term for the poloidal field. Not only the ephemeral bipolar regions could be generated in the bulk of the SCZ, but many of the smaller bipolar regions as well (at depths that increase with their flux), all contributing to the source term for the poloidal field. In contrast to the butterfly diagram that provides only a very weak test of dynamo theories, the pattern of torsional oscillations has the potential of critically discriminating between different dynamo models.

  5. Rotational Energies in Various Torsional Levels of CH_2DOH

    NASA Astrophysics Data System (ADS)

    Coudert, L. H.; Hilali, A. El; Margulès, L.; Motiyenko, R. A.; Klee, S.

    2012-06-01

    Using an approach accounting for the hindered internal rotation of a monodeuterated methyl group, an analysis of the torsional spectrum of the monodeuterated species of methanol CH_2DOH has been carried out recently and led to the assignment of 76 torsional subbands in its microwave, FIR, and IR spectra. Although this approach also allowed us to account for subband centers, the rotational structure of the torsional subbands is not well understood yet. In this paper, we will deal with the rotational energies of CH_2DOH. Analyses of the rotational structure of the available subbands^b have been performed using the polynomial-type expansion introduced in the case of the normal species of methanol. For each subband, FIR or IR transitions and a-type microwave lines, within the lower torsional level, were fitted. The frequencies of the latters were taken from previous investigations or from new measurements carried out from 50 to 950 GHz with the submillimeterwave solid state spectrometer in Lille. Subbands involving lower levels with v_t=0 and K ? 3 could be satisfactorily analyzed. For levels characterized by lower K-values, the expansion fails. In the case of the K=1, v_t=1 level, the frequencies of a-type microwave transitions involving the lower member of the K-type doublet cannot be well reproduced. For K=0 levels with v_t=1 and 2, a large number of terms is needed in the expansion. We will try to understand why the rotational energies of these levels cannot be reproduced. The results of the analyses will be compared to those obtained with a global approach based on the rotation-torsion Hamiltonian of the molecule. [2] El Hilali, Coudert, Konov, and Klee, J. Chem. Phys. 135 (2011) 194309. [3] Ioli, Moruzzi, Riminucci, Strumia, Moraes, Winnewisser, and Winnewisser, J. Mol. Spec. 171 (1995) 130. [4] Quade and Suenram, J. Chem. Phys. 73 (1980) 1127; and Su and Quade, J. Mol. Spec. 134 (1989) 290. [5] Lauvergnat, Coudert, Klee, and Smirnov, J. Mol. Spec. 256 (2009) 204.

  6. A spinning finite beam element of general orientation analyzed with Rayleigh\\/Timoshenko\\/Saint-Venant theory

    Microsoft Academic Search

    T. J. S. Abrahamsson; J. H. Saellstroem

    1996-01-01

    Linear vibrations are studied for a straight uniform finite beam element of general orientation spinning at a constant angular speed about a fixed axis in the inertial space. The gyroscopic and circulatory matrices and also the geometric stiffness matrix of the beam element are presented. The effect of the centrifugal static axial load on the bending and torsional dynamic stiffnesses

  7. The angular correlation hierarchy in the quasilinear regime.

    E-print Network

    F. Bernardeau

    1995-02-21

    For Gaussian initial conditions the perturbation theory predicts a very specific hierarchy for the projected matter $p$-point correlation functions. In the small angle approximation and assuming a power-law spectrum I derive the exact expressions of the coefficients $s_p$ relating the averaged $p$-order angular correlation function, $\\omb_p$ to the second one, $\\omb_p=s_p\\ \\omb_2^{p-1}$. These results are valid for any selection function, but for a top-hat angular filter only. These coefficients are found to be significantly higher than their 3D counterparts, $S_p=\\xib_p/\\xib_2^{p-1}$. For the coefficient $s_3$ I discussed the accuracy of the small angle approximation by computing, for particular examples, its angular dependence with Monte-Carlo numerical integrations. It is found that the accuracy of the small angle approximation for $\\theta\\approx 1^o$ slightly depends on the selection function. Using the selection function expected for galaxy catalogues the approximation is found to be reasonably good. The measurements of the $s_p$ parameters made in the APM angular survey are found to give systematic lower values than the theoretical predictions. How significant this discrepancy is and what the implications would be for galaxy formation models is discussed in the last section.

  8. Angular momentum generation from holographic Chern-Simons models

    NASA Astrophysics Data System (ADS)

    Wu, Chaolun

    2014-12-01

    We study parity-violating effects, particularly the generation of angular momentum density and its relation to the parity-odd and dissipationless transport coefficient Hall viscosity, in strongly-coupled quantum fluid systems in 2+1 dimensions using holographic method. We employ a class of 3+1-dimensional holographic models of Einstein-Maxwell system with gauge and gravitational Chern-Simons terms coupled to a dynamical scalar field. The scalar can condensate and break the parity spontaneously. We find that when the scalar condensates, a non-vanishing angular momentum density and an associated edge current are generated, and they receive contributions from both gauge and gravitational Chern-Simons terms. The angular momentum density does not satisfy a membrane paradigm form because the vector mode fluctuations from which it is calculated are effectively massive. On the other hand, the emergence of Hall viscosity is a consequence of the gravitational Chern-Simons term alone and it has membrane paradigm form. We present both general analytic results and numeric results which take back-reactions into account. The ratio between Hall viscosity and angular momentum density resulting from the gravitational Chern-Simons term has in general a deviation from the universal 1/2 value obtained from field theory and condensed matter physics.

  9. Angular Momentum Generation from Holographic Chern-Simons Models

    E-print Network

    Chaolun Wu

    2014-12-22

    We study parity-violating effects, particularly the generation of angular momentum density and its relation to the parity-odd and dissipationless transport coefficient Hall viscosity, in strongly-coupled quantum fluid systems in 2+1 dimensions using holographic method. We employ a class of 3+1-dimensional holographic models of Einstein-Maxwell system with gauge and gravitational Chern-Simons terms coupled to a dynamical scalar field. The scalar can condensate and break the parity spontaneously. We find that when the scalar condensates, a non-vanishing angular momentum density and an associated edge current are generated, and they receive contributions from both gauge and gravitational Chern-Simons terms. The angular momentum density does not satisfy a membrane paradigm form because the vector mode fluctuations from which it is calculated are effectively massive. On the other hand, the emergence of Hall viscosity is a consequence of the gravitational Chern-Simons term alone and it has membrane paradigm form. We present both general analytic results and numeric results which take back-reactions into account. The ratio between Hall viscosity and angular momentum density resulting from the gravitational Chern-Simons term has in general a deviation from the universal 1/2 value obtained from field theory and condensed matter physics.

  10. The Theory Of Gravity

    Microsoft Academic Search

    A. A. Logunov

    2002-01-01

    In the framework of the special theory of relativity, the relativistic theory of gravitation (RTG) is constructed. The energy-momentum tensor density of all the matter fields (including gravitational one) is treated as a source of the gravitational field. The energy-momentum and the angular momentum conservation laws are fulfilled in this theory. Such an approach permits us to unambiguously construct the

  11. Maintained ocular torsion produced by bilateral and unilateral galvanic (DC) vestibular stimulation in humans.

    PubMed

    Watson, S R; Brizuela, A E; Curthoys, I S; Colebatch, J G; MacDougall, H G; Halmagyi, G M

    1998-10-01

    This study was designed to measure ocular movements evoked by galvanic (DC) stimulation using computerised video-oculography. Long duration (>30 s) galvanic vestibular stimulation at currents of up to 5 mA through large-area surface electrodes over the mastoid processes causes maintained changes in the ocular torsional position of both eyes in healthy human subjects. With the subject seated and the head held firmly, torsion was measured by a computer-based image-processing system (VTM). Torsion was recorded in darkness, with or without a single fixation point. With bilateral stimulation, the upper poles of both eyes always torted away from the side of cathode placement and toward the anode. For unilateral stimulation, torsion was directed away from the cathode or toward the anode. The magnitude of ocular torsion was dependent on current strength: with bilateral stimulation the peak torsion was on average 2.88 degrees for 5-mA current intensity compared with 1.58 degrees for 3 mA. A smaller amplitude of torsion was obtained for unilateral stimulation. The average peak torsion was the same for both eyes for all forms of stimulation. Our findings indicate that low-intensity galvanic stimulation evokes ocular torsion in normal subjects, an effect which is consistent with an action on otolith afferents. PMID:9827864

  12. Left ventricular torsion: an expanding role in the analysis of myocardial dysfunction.

    PubMed

    Rüssel, Iris K; Götte, Marco J W; Bronzwaer, Jean G; Knaapen, Paul; Paulus, Walter J; van Rossum, Albert C

    2009-05-01

    During left ventricular (LV) torsion, the base rotates in an overall clockwise direction and the apex rotates in a counterclockwise direction when viewed from apex to base. LV torsion is followed by rapid untwisting, which contributes to ventricular filling. Because LV torsion is directly related to fiber orientation, it might depict subclinical abnormalities in heart function. Recently, ultrasound speckle tracking was introduced for quantification of LV torsion. This fast, widely available technique may contribute to a more rapid introduction of LV torsion as a clinical tool for detection of myocardial dysfunction. However, knowledge of the exact function and structure of the heart is fundamental for understanding the value of LV torsion. LV torsion has been investigated with different measurement methods during the past 2 decades, using cardiac magnetic resonance as the gold standard. The results obtained over the years are helpful for developing a standardized method to quantify LV torsion and have facilitated the interpretation and value of LV torsion before it can be used as a clinical tool. PMID:19442954

  13. The propagation of torsion along flux tubes subject to dynamical nonequilibrium

    NASA Technical Reports Server (NTRS)

    Parker, E. N.

    1983-01-01

    It is noted that the dynamical nonequilibrium of close-packed flux tubes is driven by the torsion in the individual tubes. Because of this, whenever tubes with the same sense of twisting come into contact, there is reconnection of their azimuthal field components. The reconnection consumes the local torsion, and this causes the propagation of torsional Alfven waves into the region from elsewhere along the tubes. The formal problem of the propagation of the torsion along twisted flux tubes is presented, along with some of the basic physical properties worked out in the limit of small torsion. It is noted that in tubes with finite twisting the propagation of torsional Alfven waves can be a more complicated phenomenon. Application to the sun suggests that the propagation of torsion from below the visible surface up into the corona is an important energy supply to the corona for a period of perhaps 10-20 hours after the emergence of the flux tubes through the surface of the sun, bringing up torsion from depths of 10,000 km or more. Torsion is of course continually furnished by the manipulation and shuffling of the field by the convection.

  14. Influence of braiding structure on torsional properties of braided composite tube

    SciTech Connect

    Nakai, A.; Hamada, H. [Kyoto Inst. of Technology (Japan). Faculty of Textile Science; Hoa, S.V. [Concordia Univ., Montreal, Quebec (Canada). Dept. of Mechanical Engineering

    1996-12-01

    Many different composite cylinders and pipes can be produced by various fabrication methods such as filament winding, prepreg rolling method, braiding technique and so on. It is desirable to understand the mechanical behavior of pipe made by the different method. In this paper torsional behavior of braided composite tube, particularly the effects of braiding angle, was investigated. Numerical model was applied to estimate the torsional rigidity. The torsional rigidity increases with increase of braiding angle from 30{degree} to 45{degree}. However above 45{degree} braiding angle the torsional rigidity remains constant. These results can be compared to numerical results.

  15. The effect of torsional muscle dysfunction and surgery on eye position under general anesthesia.

    PubMed

    McCall, L C; Isenberg, S J; Apt, L

    1993-01-01

    Under general anesthesia, normal eyes exhibit 2.0 degrees to 2.5 degrees of extorsion. To investigate the effect of torsional muscle dysfunction and surgery on eye position under general anesthesia, we measured the torsional change before and after torsional muscle surgery in 26 eyes of 18 patients with clinical torsional muscle dysfunction. Under general anesthesia, compared with normals, eyes with preoperative intorter overaction or extorter underaction demonstrated a significant intorsional change (P < .01). However, eyes with intorter underaction or extorter overaction did not demonstrate a significant extorsional change. Postoperatively, while patients remained under general anesthesia, intorter weakening procedures produced measurable extorsion while intorter strengthening procedures and extorter weakening procedures produced measurable intorsion. Superior oblique tenotomy produced a greater net torsional change than inferior oblique weakening surgery (P < .01). Under general anesthesia, eyes with preoperative torsional muscle dysfunction exhibit torsion in the direction consistent with the dysfunction. After surgery on the torsional muscles, a measurable torsional effect can be demonstrated while the patient is still under general anesthesia. PMID:8350223

  16. PP-waves with Torsion - a Metric-affine Model for the Massless Neutrino

    E-print Network

    Vedad Pasic; Elvis Barakovic

    2014-09-03

    In this paper we deal with quadratic metric-affine gravity, which we briefly introduce, explain and give historical and physical reasons for using this particular theory of gravity. Further, we introduce a generalisation of well known spacetimes, namely pp-waves. A classical pp-wave is a 4-dimensional Lorentzian spacetime, which admits a nonvanishing parallel spinor field; here the connection is assumed to be Levi-Civita. This definition was generalised in our previous work to metric compatible spacetimes with torsion and used to construct new explicit vacuum solutions of quadratic metric-affine gravity, namely generalised pp-waves of parallel Ricci curvature. The physical interpretation of these solutions we propose in this article is that they represent a conformally invariant metric-affine model for a massless elementary particle. We give a comparison with the classical model describing the interaction of gravitational and massless neutrino fields, namely Einstein-Weyl theory and construct pp-wave type solutions of this theory. We point out that generalised pp-waves of parallel Ricci curvature are very similar to pp-wave type solutions of the Einstein-Weyl model and therefore propose that our generalised pp-waves of parallel Ricci curvature represent a metric-affine model for the massless neutrino.

  17. Stability of elastic bending and torsion of uniform cantilever rotor blades in hover with variable structural coupling

    NASA Technical Reports Server (NTRS)

    Hodges, D. H., Roberta.

    1976-01-01

    The stability of elastic flap bending, lead-lag bending, and torsion of uniform, untwisted, cantilever rotor blades without chordwise offsets between the elastic, mass, tension, and areodynamic center axes is investigated for the hovering flight condition. The equations of motion are obtained by simplifying the general, nonlinear, partial differential equations of motion of an elastic rotating cantilever blade. The equations are adapted for a linearized stability analysis in the hovering flight condition by prescribing aerodynamic forces, applying Galerkin's method, and linearizing the resulting ordinary differential equations about the equilibrium operating condition. The aerodynamic forces are obtained from strip theory based on a quasi-steady approximation of two-dimensional unsteady airfoil theory. Six coupled mode shapes, calculated from free vibration about the equilibrium operating condition, are used in the linearized stability analysis. The study emphasizes the effects of two types of structural coupling that strongly influence the stability of hingeless rotor blades. The first structural coupling is the linear coupling between flap and lead-lag bending of the rotor blade. The second structural coupling is a nonlinear coupling between flap bending, lead-lag bending, and torsion deflections. Results are obtained for a wide variety of hingeless rotor configurations and operating conditions in order to provide a reasonably complete picture of hingeless rotor blade stability characteristics.

  18. Angular Momentum and Gravimagnetization of the ${\\cal N}=2$ SYM vacuum

    E-print Network

    A. Gorsky

    2011-02-09

    In this note we discuss the gravimagnetization of the ${\\cal N}=2$ SYM vacuum in the $\\Omega$-background. It is argued that the Seiberg-Witten prepotential is related to the vacuum density of the angular momentum in the Euclidean $R^4$ space. The possible role of the dyonic instantons as the microscopic angular momentum carriers which could yield the spontaneous vacuum gravimagnetization is conjectured. We interpret the dyonic instanton as a kind of the Euclidean bounce in $R^4$ similar to one responsible for the Schwinger pair creation. The induced angular momentum in $R^4$ is also briefly considered in the dual Liouville formulation of $SU(2)$ theory via AGT relation.

  19. Symmetric angular momentum coupling, the quantum volume operator and the 7-spin network: a computational perspective

    E-print Network

    Marinelli, Dimitri; Aquilanti, Vincenzo; Anderson, Roger W; Bitencourt, Ana Carla P; Ragni, Mirco

    2014-01-01

    A unified vision of the symmetric coupling of angular momenta and of the quantum mechanical volume operator is illustrated. The focus is on the quantum mechanical angular momentum theory of Wigner's 6j symbols and on the volume operator of the symmetric coupling in spin network approaches: here, crucial to our presentation are an appreciation of the role of the Racah sum rule and the simplification arising from the use of Regge symmetry. The projective geometry approach permits the introduction of a symmetric representation of a network of seven spins or angular momenta. Results of extensive computational investigations are summarized, presented and briefly discussed.

  20. Cross-axis adaptation of torsional components in the yaw-axis vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Trillenberg, P.; Shelhamer, M.; Roberts, D. C.; Zee, D. S.

    2003-01-01

    The three pairs of semicircular canals within the labyrinth are not perfectly aligned with the pulling directions of the six extraocular muscles. Therefore, for a given head movement, the vestibulo-ocular reflex (VOR) depends upon central neural mechanisms that couple the canals to the muscles with the appropriate functional gains in order to generate a response that rotates the eye the correct amount and around the correct axis. A consequence of these neural connections is a cross-axis adaptive capability, which can be stimulated experimentally when head rotation is around one axis and visual motion about another. From this visual-vestibular conflict the brain infers that the slow-phase eye movement is rotating around the wrong axis. We explored the capability of human cross-axis adaptation, using a short-term training paradigm, to determine if torsional eye movements could be elicited by yaw (horizontal) head rotation (where torsion is normally inappropriate). We applied yaw sinusoidal head rotation (+/-10 degrees, 0.33 Hz) and measured eye movement responses in the dark, and before and after adaptation. The adaptation paradigm lasted 45-60 min, and consisted of the identical head motion, coupled with a moving visual scene that required one of several types of eye movements: (1) torsion alone (-Roll); (2) horizontal/torsional, head right/CW torsion (Yaw-Roll); (3) horizontal/torsional, head right/CCW torsion (Yaw+Roll); (4) horizontal, vertical, torsional combined (Yaw+Pitch-Roll); and (5) horizontal and vertical together (Yaw+Pitch). The largest and most significant changes in torsional amplitude occurred in the Yaw-Roll and Yaw+Roll conditions. We conclude that short-term, cross-axis adaptation of torsion is possible but constrained by the complexity of the adaptation task: smaller torsional components are produced if more than one cross-coupling component is required. In contrast, vertical cross-axis components can be easily trained to occur with yaw head movements.

  1. Semiclassical model for attosecond angular streaking.

    PubMed

    Smolarski, M; Eckle, P; Keller, U; Dörner, R

    2010-08-16

    Attosecond angular streaking is a new technique to achieve unsurpassed time accuracy of only a few attoseconds. Recently this has been successfully used to set an upper limit on the electron tunneling delay time in strong laser field ionization. The measurement technique can be modeled with either the time-dependent Schrödinger equation (TDSE) or a more simple semiclassical approach that describes the process in two steps in analogy to the three-step model in high harmonic generation (HHG): step one is the tunnel ionization and step two is the classical motion in the strong laser field. Here we describe in detail a semiclassical model which is based on the ADK theory for the tunneling step, with subsequent classical propagation of the electron in the laser field. We take into account different ellipticities of the laser field and a possible wavelength-dependent ellipticity that is typically observed for pulses in the two-optical-cycle regime. This semiclassical model shows excellent agreement with the experimental result. PMID:20721150

  2. Angular Power Spectrum in Modular Invariant Inflation Model

    SciTech Connect

    Hayashi, Mitsuo J.; Okame, Y.; Takagi, K.; Watanabe, T. [Department of Physics, Tokai University, 1117 Kitakaname, Hiratsuka, 259-1292 (Japan); Hirai, S.; Takami, T. [Department of Digital Games, Osaka Electro-Communication University, 1130-70 Kiyotaki, Shijonawate, Osaka, 575-0063 (Japan)

    2008-05-29

    A scalar potential of inflation is proposed and the angular power spectra of the adiabatic density perturbations are computed. The potential consists of three scalar fields, S, Y and T, together with two free parameters. By fitting the parameters to cosmological data at the fixed point T = 1, we find that the potential behaves like the single-field potential of S, which slowly rolls down. We further show that the inflation predictions corresponding to this potential provide a good fit to the recent three-year WMAP data, e.g. the spectral index n{sub s} = 0.951.The TT and TE angular power spectra obtained from our model almost completely coincide with the corresponding results obtained from the {lambda}CDM model. We conclude that our model is considered to be an adequate theory of inflation that explains the present data.

  3. Torsional dependence of molecular electrical properties and long-range interactions: CH3OH-rare gas systems

    NASA Astrophysics Data System (ADS)

    Davis, Stephen L.; Dennison, Elizabeth C.

    1994-07-01

    Self-consistent-field (SCF) values are reported for all Cartesian tensor components of the dipole, quadrupole, and octupole moments (?,?,?) and polarizabilities ? and A of the methanol molecule in its staggered, eclipsed, and three intermediate conformations. The methanol geometry was held rigid except for a single internal rotation angle ?, describing the relative orientation of the methyl rotor and the hydroxyl framework. Three different basis sets were used, including a 110 contracted Gaussian set based on the electrical properties (ELP) basis of Dykstra et al. [Adv. Chem. Phys. 75, 37 (1989), and references therein]. It was found that the tensor components ?xxx, ?xyy, Axxx, Axyy, and Ayxy vary as cos 3?, while the components ?yyy, ?yxx, Ayyy, Ayxx, and Axyx vary as sin 3?. All other components of ? and A, as well as all components of ?, ?, show little variation with ?. This dependence was explained using a simple model that treats each property as a sum of a constant, hydroxyl framework contribution and a conformation-dependent, methyl rotor contribution. Torsional averages of these properties were computed from torsional wave functions obtained by diagonalization of the internal axis method (IAM) Hamiltonian. It was found that the large amplitude internal rotation in methanol gives rise to large vibrational effects on the Axxx, Axyy, and Ayxy polarizability components. The conformational dependence of the electrical properties was used to describe the conformational dependence of long-range interactions involving a near-symmetric, nonrigid molecule such as methanol. The leading ?-dependent interaction term was shown to vary as R-8 and R-7 for the induction and dispersion interactions (respectively) between a methanol molecule and a structureless atom. Cartesian tensor expressions are given for the long-range dispersion interaction within second-order perturbation theory, and the leading torsionally dependent interaction is shown to vary as sin3 ? cos 3(?-?), where ?,? are the spherical coordinates of the atom.

  4. Kinematic Identification of the Angular Power Distribution and the Linear Polarization of Radiation of an Arbitrarily Moving Charge

    NASA Astrophysics Data System (ADS)

    Bagrov, V. G.; Bordovitsyn, V. A.; Bulenok, V. G.; Kulikova, A. V.

    2015-06-01

    Methods of the classical theory of relativistic radiation are used to investigate general properties of the total angular power distribution of radiation of a charge and to analyze the corresponding components of linearly polarized radiation emitted by this charge.

  5. Cosmological constant and Euclidean space from nonperturbative quantum torsion

    NASA Astrophysics Data System (ADS)

    Dzhunushaliev, Vladimir

    2015-10-01

    Heisenberg's nonperturbative quantization technique is applied to the nonperturbative quantization of gravity. An infinite set of equations for all Green's functions is obtained. An approximation is considered where: (a) the metric remains as a classical field; (b) the affine connection can be decomposed into classical and quantum parts; (c) the classical part of the affine connection is the Christoffel symbols; (d) the quantum part is the torsion. Using a scalar and vector fields approximation it is shown that nonperturbative quantum effects give rise to a cosmological constant and an Euclidean solution.

  6. Strength Tests on Thin-walled Duralumin Cylinders in Torsion

    NASA Technical Reports Server (NTRS)

    Lundquist, Eugene E

    1932-01-01

    This report is the first of a series presenting the results of strength tests on thin-walled cylinders and truncated cones of circular and elliptical section; it comprises the results obtained to date from torsion (pure shear) tests on 65 thin-walled duralumin cylinders of circular section with ends clamped to rigid bulkheads. The effect of variations in the length/radius and radius/thickness ratios on the type of failure is indicated, and a semi-empirical equation for the shearing stress at maximum load is given.

  7. The torsional potential energy function of N2O4

    NASA Astrophysics Data System (ADS)

    Koput, J.; Seibert, J. W. G.; Winnewisser, B. P.

    1993-03-01

    The infrared spectrum of dinitrogen tetroxide, N2O4, has been measured in the region 200?650 cm-1 at different resolutions and temperatures. Analysis of the sequence of weak bands near 540 cm-1 involving a combination of the v6 (NO2 rocking) and v4 (torsion) modes has been performed. As a result, the shape of the potential energy function governing internal rotation about the NN bond has been determined. In the ground vibrational state, the height of the barrier at the staggered conformation is determined to be 1900 ± 200 cm-1.

  8. Deformation of olivine in torsion under hydrous conditions

    NASA Astrophysics Data System (ADS)

    Demouchy, Sylvie; Tommasi, Andréa; Barou, Fabrice; Mainprice, David; Cordier, Patrick

    2012-08-01

    We performed torsional deformation experiments on pre-hydrated fine-grained olivine aggregates using an innovative experimental assembly to investigate water weakening in mantle rocks at high shear strains. San Carlos olivine powder was cold-pressed and then hot-pressed under hydrous conditions, producing aggregates with average grain sizes of 7 or 15 ?m. Deformation experiments were performed in a high-resolution gas-medium apparatus equipped with a torsional actuator, under a confining pressure of 300 MPa, a temperature of 1200 °C, and constant shear strain rates ranging from 8 × 10-5 to 1.4 × 10-4 s-1. Maximum shear stresses range from 150 to 195 MPa. These values are 30% lower relative to those determined in previous torsion experiments on dry, fined-grained dunites under similar conditions. Textures and microstructures of the starting and deformed specimens were characterized by scanning and transmission electron microscopy. All deformed aggregates exhibit a shape-preferred orientation marking a foliation and lineation, as well as a reduction in mean grain size from 15 ?m down to 3-4 ?m due to dynamic recrystallization. Olivine crystallographic fabrics developed rapidly (? < 0.1), but their strength, characterized by the J-index, is low compared to naturally deformed peridotites or to polycrystalline olivine deformed at similar finite shear strains under dry conditions. The crystallographic fabrics are consistent with deformation by a dislocation accommodated creep mechanism with activation of multiple {0 k l}[1 0 0] systems, among which the (0 1 0)[1 0 0] slip system is dominant, and minor participation of the (0 1 0)[0 0 1] slip system. Transmission electron microscopy confirmed the occurrence of dislocations with [1 0 0] and [0 0 1] Burgers vectors in most grains. Analysis of unpolarized infrared spectra indicates that hydrogen concentration in the olivine lattice is below the saturation level of 18 ppm wt H2O, which is similar to those typically observed in spinel-bearing peridotite xenoliths, and also provide evidence for water-rich inter-granular material trapped in pores and grain boundaries. Seismic properties computed from the CPO observations correspond to those most commonly observed in naturally deformed mantle peridotites with fast P-wave propagation and S-wave polarization subparallel to the shear direction. These torsion experiments on fine-grained olivine polycrystals under hydrous conditions indicate that water weakening under lithospheric conditions is linked to various defects with hydrogen in the olivine structure, as well as with water-derived species in grain boundaries or pores.

  9. Torsional Response and Dissipationless Viscosity in Topological Insulators

    E-print Network

    Taylor L. Hughes; Robert G. Leigh; Eduardo Fradkin

    2011-01-18

    We consider the visco-elastic response of the electronic degrees of freedom in 2D and 3D topological insulators (TI). Our primary focus is on the 2D Chern insulator which exhibits a bulk dissipationless viscosity analogous to the quantum Hall viscosity predicted in integer and fractional quantum Hall states. We show that the dissipationless viscosity is the response of a TI to torsional deformations of the underlying lattice geometry. The visco-elastic response also indicates that crystal dislocations in Chern insulators will carry momentum density. We briefly discuss generalizations to 3D which imply that time-reversal invariant TI's will exhibit a quantum Hall viscosity on their surfaces.

  10. Measurement of Silver-? Interactions in Solution Using Molecular Torsion Balances.

    PubMed

    Maier, Josef M; Li, Ping; Hwang, Jungwun; Smith, Mark D; Shimizu, Ken D

    2015-07-01

    A new series of molecular torsion balances were designed to measure the strength of individual Ag-? interactions in solution for an Ag(I) coordinated to a pyridine nitrogen. The formation of a well-defined intramolecular Ag-? interaction in these model systems was verified by X-ray crystallography and (1)H NMR. The strength of the intramolecular Ag-? interaction in solution was found to be stabilizing in nature and quantified to be -1.34 to -2.63 kcal/mol using a double mutant cycle analysis. The Ag-? interaction was also found to be very sensitive to changes in geometry or solvent environment. PMID:26069987

  11. Analysis of the Lowest In-Plane Bend and First Excited Torsional State of CH_3CH_2CN

    NASA Astrophysics Data System (ADS)

    Brauer, Carolyn S.; Pearson, John C.; Drouin, Brian J.; Yu, Shanshan

    2009-06-01

    Propionitrile (CH_3CH_2CN) is observed with large column densities in a number of high-mass star-forming cores, where core temperatures exceed 200 K. It is a near-prolate (?=0.96) asymmetric top with appreciable dipole moment components on both the a- and b-axes (?_a = 3.84 D, ?_b = 1.23 D). This, combined with the presence of four fundamental modes as well as four overtones and combination bands all occurring below 600 cm^{-1}, results in a very rich spectrum. It is known to be a major contributor to spectral line confusion in ground-based observations and is expected to complicate observations by Herschel, SOFIA and ALMA, making it imperative to fully characterize the entire spectrum. The lowest in-plane bend, ?_{13}, is 206.9(0.5) cm^{-1}, and the first excited torsional state, ?_{21}, which is just 186 GHz above, have been detected in hot cores with antenna temperatures of a few Kelvin. The close proximity of ?_{13} and ?_{21}, as well as their low-lying nature, offers a unique opportunity to study the vibration-torsion-rotation coupling problem in the case of two nearly degenerate vibrational states. As expected from C_s symmetry and their A^' and A^'' nature, these states exhibit strong a- and b-symmetry Coriolis interactions, as well as interactions resulting from different sets of Eckhart-Sayvetz conditions being required in ?_{13} and ?_{21}. In the present work, the ?_{13} and ?_{21} states of propionitrile have been analyzed to high frequency and angular momentum quantum number. The spectrum, molecular constants,and insights into the vibration-torsion-rotation problem will be discussed. H. M. Heise, H. Lutz & H. Dreizler,Z.Nat.,29a,1345 (1974). H. M. Heise, F. Winther & H. Lutz,J. Mol. Spectrosc.,90,531 (1981). D. M. Mehringer, J. C. Pearson, J. Keene & T. G. Phillips,Ap.J.,608,306 (2004).

  12. L 2 TORSION WITHOUT THE DETERMINANT CLASS CONDITION AND EXTENDED L 2 COHOMOLOGY

    E-print Network

    Durham, University of

    L 2 TORSION WITHOUT THE DETERMINANT CLASS CONDITION AND EXTENDED L 2 COHOMOLOGY MAXIM BRAVERMAN + , ALAN CAREY # , MICHAEL FARBER # , AND VARGHESE MATHAI # Abstract. We associate determinant lines class condition. The resulting torsions are elements of the determinant line of the extended L 2

  13. TORSION SIMPLIFIED: A FAILURE PLANE MODEL FOR DESIGN OF SPANDREL BEAMS

    E-print Network

    torsion must also resist shear, and, as such, failure will occur along a plane inclined upward toward, as such, failure will occur along a plane inclined upward toward #12;3 midspan. By dividing torsion into bending and twist components that act on the inclined plane, the design model provides a direct procedure

  14. Development of a cost-effective torsional unit for rodent long bone assessment

    Microsoft Academic Search

    M. M. Saunders; R. B. Burger; B. Kalantari; A. D. Nichols; C. Witman

    2010-01-01

    Thorough mechanical testing of rodent bones requires an understanding of bone behavior in a variety of loading modes including tension, compression, bending and shear. While these tests are easily conducted with single axis mechanical testing machines, it may also be desirable to determine torsional properties of bone. Although higher-end materials testing machines will enable torsional and\\/or rotational testing, simpler, less

  15. THE CONJECTURE OF TATE AND VOLOCH ON p-ADIC PROXIMITY TO TORSION

    E-print Network

    Scanlon, Thomas

    and Voloch have conjectured that the p-adic distance from torsion points of semi-abelian varieties over Cp and Voloch conjectured: Conjecture: (Tate, Voloch) Let G be a semi-abelian variety over Cp. Let X G be a subvariety defined over Cp. Then there is a constant N N such that for any torsion point G(Cp)tor either

  16. Flexural–torsional post-buckling analysis of thin-walled elements with open sections

    Microsoft Academic Search

    F. Mohri; L. Azrar; M. Potier-Ferry

    2001-01-01

    The post-buckling analysis of thin-walled elements under compression is investigated. A nonlinear model is developed by using nonlinear relationships between curvatures and bending moments. Warping and shortening effects are considered in the torsion equilibrium equation. Based on Galerkin's method, a nonlinear algebraic system is obtained for simply supported boundary conditions. The three resulting equations in bending and torsion are highly

  17. Polymer-MEMS torsion mirror with large rotation angle and low driving voltage

    Microsoft Academic Search

    Dzung Viet Dao; Satoshi Amaya; Susumu Sugiyama

    2010-01-01

    This paper presents a novel fabrication of a monolithic PMMA torsional mirror utilizing hot embossing, surface-activated direct bonding, and the elliptical vibration cutting. The robustness and capability of the method are demonstrated through the fabrication of sophisticated PMMA freestanding micro structures. An efficient technique using reinforcement material to protect the PMMA microstructures during release process was proposed. Monolithic PMMA torsional

  18. Elliptic curves with large torsion and positive rank over number fields of small degree and ECM

    E-print Network

    Dujella, Andrej

    Elliptic curves with large torsion and positive rank over number fields of small degree and ECM for construction of elliptic curves with large torsion group and positive rank over number fields of small degree. We also discuss potential applications of such curves in the elliptic curve factorization method (ECM

  19. Highly Accurate Beam Torsion Solutions Using the p-Version Finite Element Method

    NASA Technical Reports Server (NTRS)

    Smith, James P.

    1996-01-01

    A new treatment of the classical beam torsion boundary value problem is applied. Using the p-version finite element method with shape functions based on Legendre polynomials, torsion solutions for generic cross-sections comprised of isotropic materials are developed. Element shape functions for quadrilateral and triangular elements are discussed, and numerical examples are provided.

  20. Creep-Fatigue Life Evaluation for Materials Subjected to Nonproportionally Combined Tension and Torsion

    Microsoft Academic Search

    Katsuyuki Tokimasa

    2011-01-01

    The author and his colleagues have proposed in their recent works the creep-fatigue life prediction method based on the strain range partitioning concept for nonproportionally combined tension and torsion using new inelastic strain range parameters and have been studying their applicability to the materials subjected to nonproportional axial-torsional loading at elevated temperatures. In the present paper are summarized the results

  1. Shear strength of a ductile material from torsion of solid cylinders

    Microsoft Academic Search

    RE Lyon

    1991-01-01

    This paper discusses the shear strengths of two ductile epoxies obtained from solid cylinder torsion using a data reduction scheme. The results are in quantitative agreement with shear data from torsion of thin-walled tubes of the same materials, particularly with regard to the coincidence of the peak yield stress and strain. The described technique is useful for characterizing ductile material

  2. New action principle for classical particle trajectories in spaces with torsion

    Microsoft Academic Search

    P. Fiziev; H. Kleinert

    1996-01-01

    To comply with recent developments of path integrals in spaces with curvature and torsion, we find the correct variational principle for classical trajectories of spinless point-particles in such spaces. Although the action depends only on the length, the trajectories are autoparallels (straightest lines) rather than geodesics (shortest lines), due to the effects of a torsion force arising from a geometric

  3. New Action Principle for Classical Particle Trajectories in Spaces with Torsion

    E-print Network

    P. Fiziev; H. Kleinert

    1995-03-11

    To comply with recent developments of path integrals in spaces with curvature and torsion we find the correct variational principle for the classical trajectories. Although the action depends only on the length, the trajectories are {\\em autoparallels} rather than geodesics due to the effects of a new torsion force.

  4. Torsional Control of Stereoselectivities in Electrophilic Additions and Cycloadditions to Alkenes

    PubMed Central

    Wang, Hao; Houk, K. N.

    2013-01-01

    Torsional effects control the ?-facial stereoselectivities of a variety of synthetically important organic reactions. This review surveys theoretical calculations that have led to the understanding of the influence of the torsional effects on several types of stereoselective organic reactions, especially electrophilic additions and cycloadditions to alkenes. PMID:24409340

  5. Prenatal observation of umbilical cord abnormalities: a triple knot and torsion of the umbilical cord.

    PubMed

    Collins, J C; Muller, R J; Collins, C L

    1993-07-01

    Umbilical cord abnormalities can be observed with ultrasonography. Two cases are described where a triple knot and torsion of the umbilical cord are observed. These cases allow the elucidation of the mechanics of formation of a triknot and torsion abnormality. PMID:8333430

  6. High Cycle Cyclic Torsion Fatigue of PBGA Pb-Free Solder Joints

    Microsoft Academic Search

    Haiyu Qi; Qian Zhang; Edwin C. Tinsley; Michael Osterman; Michael G. Pecht

    2008-01-01

    In this study, a comprehensive experimental and numerical approach was used to investigate high cycle cyclic torsion fatigue behavior of lead-free solder joints in a plastic ball grid array (PBGA) package. The test vehicle was a commercial laptop motherboard. The motherboard was subjected to torsional loading and life tests were conducted. Using finite element analysis (FEA), the test assembly was

  7. A general approach of damping torsional resonance modes in multi-megawatt applications

    Microsoft Academic Search

    Joseph Song-Manguelle; Christof Sihler; Simon Schramm

    2010-01-01

    In large drive applications load-commutated inverters (LCIs) are one of the most used technologies, mainly because of their excellent reliability records. However, LCIs are known to generate interharmonics. They can interact with the mechanical system at torsional natural torsional frequencies of the rotating train, both on the inverter and on rectifier side in weakly connected power systems, such as offshore

  8. Flap/Lag/Torsion Dynamics of a Uniform, Cantilever Rotor Blade in Hover

    NASA Technical Reports Server (NTRS)

    Johnson, W.

    1977-01-01

    The dynamic stability of the flap/lag/torsion motion of a uniform, cantilever rotor blade in hover is calculated. The influence of blade collective pitch, lag frequency, torsional flexibility, structural coupling, and precone angle on the stability is examined. Good agreement is found with the results of an independent analytical investigation.

  9. MAXIMAL TORSION RADICALS IN [M] AND MINIMAL PRIME M-IDEALS

    E-print Network

    Beachy, John

    MAXIMAL TORSION RADICALS IN [M] AND MINIMAL PRIME M-IDEALS John A. Beachy Department of Mathematics torsion radicals of R­Mod. In this paper conditions are given under which this result can be extended M-prime module RX. A subfunctor of the identity on R­Mod is called a radical of R­Mod if (X

  10. Torsional Alfvén waves: magneto-seismology in static and dynamic coronal plasmas

    Microsoft Academic Search

    R. J. Morton; M. S. Ruderman; R. Erdélyi

    2011-01-01

    Aims: We study the properties of torsional Alfvén waves in coronal loops so that they may be exploited for coronal seismological applications. Methods: The governing equation is obtained for standing torsional Alfvén waves of a dynamic, gravitationally stratified plasma. The footpoints are assumed to obey line-tying conditions necessary for standing oscillations. Solutions are found in a number of different but

  11. Torsion Property and Cyclic Fatigue Fracture Behavior of Nickel-Titanium Endodontic Instruments

    E-print Network

    Zheng, Yufeng

    of nickel titanium alloy have been studied by means of Shimadzu Autograph DDS-10T universal tester and manTorsion Property and Cyclic Fatigue Fracture Behavior of Nickel-Titanium Endodontic Instruments gloomice@163.com, d lczhao@hit.edu.cn Keywords: NiTi alloy; Torsion; Cyclic fatigue; Endodontic instrument

  12. Contribution of Power System Stabilizers to the Damping of Torsional Oscillations of Large Turbo Generators

    Microsoft Academic Search

    A. M. El-Serafi; M. Y. Niamat; E. Haq

    1986-01-01

    In this paper, the damping torque contributions of power and speed based stabilizers and the effects of these damping torques on the torsional oscillations of large turbo-generators have been investigated under various operating conditions. The results of these investigations show that, in the case of uncompensated power systems, the power based stabilizers introduce almost no damping in the torsional frequency

  13. Virtually free pro-p groups whose torsion elements have finite centralizers

    E-print Network

    Zalesskii, Pavel

    Virtually free pro-p groups whose torsion elements have finite centralizers W. Herfort University-DF, Brazil pz@mat.unb.br July 15, 2006 Abstract It is shown that a finitely generated virtually free pro-p group G with finite centralizers of its torsion elements is the free pro-p product of finite p

  14. Trade-offs between Angular and Spatial Resolution in High Angular Resolution Diffusion Imaging

    E-print Network

    Thompson, Paul

    Trade-offs between Angular and Spatial Resolution in High Angular Resolution Diffusion Imaging. Jack Jr4 , Arthur W. Toga1 , Paul M. Thompson1 1 Laboratory of Neuro Imaging, Dept. of Neurology, UCLA question for DTI is how to allocate the scanning time: higher spatial resolution or more angular resolution

  15. Angular Momentum Operators from Quantized SO(3)

    E-print Network

    Ahmad Adel Abutaleb

    2015-04-08

    In this paper, we derive the form of the angular momentum matrices and angular momentum operators in the case of quantized rotations. We find an indication of the need to change all quantum mechanical operators at very small scale (High Energy level) if we assume a quantized nature of the Spacetime.

  16. Angular momentum control in coordinated Victor Zordan

    E-print Network

    Zordan, Victor

    in computer animation, biomechanics, and robotics have begun to explore the ability to produce whole-body control over whole-body rotation. With such compelling evidence and findings in biomechanics of the role of angular momentum in human movement to date. They postulate that whole-body (spin) angular

  17. Angular-Rate Estimation Using Quaternion Measurements

    NASA Technical Reports Server (NTRS)

    Azor, Ruth; Bar-Itzhack, Y.; Deutschmann, Julie K.; Harman, Richard R.

    1998-01-01

    In most spacecraft (SC) there is a need to know the SC angular rate. Precise angular rate is required for attitude determination, and a coarse rate is needed for attitude control damping. Classically, angular rate information is obtained from gyro measurements. These days, there is a tendency to build smaller, lighter and cheaper SC, therefore the inclination now is to do away with gyros and use other means and methods to determine the angular rate. The latter is also needed even in gyro equipped satellites when performing high rate maneuvers whose angular-rate is out of range of the on board gyros or in case of gyro failure. There are several ways to obtain the angular rate in a gyro-less SC. When the attitude is known, one can differentiate the attitude in whatever parameters it is given and use the kinematics equation that connects the derivative of the attitude with the satellite angular-rate and compute the latter. Since SC usually utilize vector measurements for attitude determination, the differentiation of the attitude introduces a considerable noise component in the computed angular-rate vector.

  18. Optical angular momentum in periodic arrays

    Microsoft Academic Search

    R. Zambrini; M. Vasnetsov; M. Dennis; J. Courtial

    2005-01-01

    This paper studies the optical angular momentum in periodic arrays. This work shows a gray-scale representation of the phase cross-section of a periodic array of optical vortices. The phase gradient gives rise to transverse linear momentum, which in turn leads to a nonvanishing angular momentum density.

  19. Angular minimum uncertainty states with large uncertainties

    Microsoft Academic Search

    Jörg B Götte; Paul M. Radmore; Roberta Zambrini; Stephen M. Barnett

    2006-01-01

    The uncertainty relation for angle and angular momentum has a lower bound which depends on the form of the state. Surprisingly, this lower bound can be very large. We derive the states which have the lowest possible uncertainty product for a given uncertainty in the angle or in the angular momentum. We show that, if the given angle uncertainty is

  20. Angular momenta of modeled ocean gyres

    Microsoft Academic Search

    Greg Holloway; Peter Rhines

    1991-01-01

    Total angular momentum of fluid within an ocean basin consists of a part due to center of mass of the fluid rotating about Earth's axis and a part due to relative motion within the basin. In rotating planar geometry (f plane) the relative angular momentum due to motion within a basin can be expressed as an integral of mass transport

  1. Specific Angular Momentum of Extrasolar Planetary Systems

    E-print Network

    John C. Armstrong; Shane L. Larson; Rhett R. Zollinger

    2011-09-02

    As the number of known planetary systems increases, the ability to follow-up and characterize the extent of any system becomes limited. This paper considers the use of specific angular momentum as a metric to prioritize future observations. We analyze 431 planets in 367 known extrasolar planetary systems from Butler et al. (2006) (including updates to their online catalog, current to April, 2011) and estimate each system's orbital angular momentum. The range of partition- ing of specific angular momentum in these systems is found to be large, spanning several orders of magnitude. The analysis shows that multi-planet systems tend to have the highest values of specific angular momentum normalized against the planetary masses. This suggests that in high angular momentum systems, the dominant contributors have already been discovered, and that single-planet sys- tems with low observed angular momentum may be the most likely candidates for additional undiscovered companions compared to their high angular momentum, single-planet counterparts. The multi-planet system, GJ 581, is considered as a historical case study to demonstrate the concept, examining how the specific angular momentum of the know planetary system evolved with each discovery.

  2. Orbital angular momentum in the nucleon

    SciTech Connect

    Garvey, Gerald T. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2010-05-15

    Analysis of the measured value of the integrated d-bar-u-bar asymmetry (I{sub fas} = 0.147 +- 0.027) in the nucleon show it to arise from nucleon fluctuations into baryon plus pion. Requiring angular momentum conservation in these fluctuations shows the associated orbital angular momentum is equal to the value of the flavor asymmetry.

  3. Do springboard divers violate angular momentum conservation?

    Microsoft Academic Search

    Cliff Frohlich

    1979-01-01

    No. However, divers and trampolinists can perform somersaults and twists even though they have zero angular momentum at all times during the stunt. Also, if a diver is somersaulting in space and possesses angular momentum only about his somersaulting axis, he can make a single discrete change in the position of his arms which initiates continuous twisting motion even in

  4. Considerations on the implementation and modeling of an active mass driver with electric torsional servomotor

    NASA Astrophysics Data System (ADS)

    Ubertini, Filippo; Venanzi, Ilaria; Comanducci, Gabriele

    2015-06-01

    The current trend in full-scale applications of active mass drivers for mitigating buildings' vibrations is to rely on the use of electric servomotors and low friction transmission devices. While similar full-scale applications have been recently documented, there is still the need for deepening the understanding of the behavior of such active mass drivers, especially as it concerns their reliability in the case of extreme loading events. This paper presents some considerations arisen in the physical implementation of a prototype active mass driver system, fabricated by coupling an electric torsional servomotor with a ball screw transmission device, using state-of-the-art electronics and a high speed digital communication protocol between controller and servomotor drive. The prototype actuator is mounted on top of a scaled-down five-story frame structure, subjected to base excitation provided by a sliding table actuated by an electrodynamic shaker. The equations of motion are rigorously derived, at first, by considering the torque of the servomotor as the control input, in agreement with other literature work. Then, they are extended to the case where the servomotor operates under kinematic control, that is, by commanding its angular velocity instead of its torque, including control-structure-interaction effects. Experiments are carried out by employing an inherently stable collocated skyhook control algorithm, proving, on the one hand, the control effectiveness of the device but also revealing, on the other hand, the possibility of closed-loop system instability at high gains. Theoretical interpretation of the results clarifies that the dynamic behavior of the actuator plays a central role in determining its control effectiveness and is responsible for the observed stability issues, operating similarly to time delay effects. Numerical extension to the case of earthquake excitation confirms the control effectiveness of the device and highlights that different controllers essentially provide similar performances in the mitigation of the structural response.

  5. Rotation–torsion analysis of the Si2H6 infrared fundamental ?9, perturbed by excited torsional levels of the vibrational ground state

    Microsoft Academic Search

    F. Lattanzi; C. Di Lauro; V.-M. Horneman

    2004-01-01

    The lowest infrared active perpendicular fundamental ?9 of disilane has been analysed on a Fourier transform spectrum between 320 and 430?cm, at the spectral resolution of 0.0012?cm. The rotation–torsion structure of this band is affected by x,y Coriolis interactions with excited torsional levels of the vibrational ground state, correlating with components of 3?4 and 4?4 in the high barrier limit.

  6. Rotation-torsion analysis of the Si2H6 infrared fundamental nu, perturbed by excited torsional levels of the vibrational ground state

    Microsoft Academic Search

    F. Lattanzi; C. di Lauro; V.-M. Horneman

    2004-01-01

    The lowest infrared active perpendicular fundamental nu9 of disilane has been analysed on a Fourier transform spectrum between 320 and 430 cm-1, at the spectral resolution of 0.0012 cm-1. The rotation-torsion structure of this band is affected by x,y Coriolis interactions with excited torsional levels of the vibrational ground state, correlating with components of 3nu4 and 4nu4 in the high

  7. Impact of synchronous machine constants and models on the analysis of torsional dynamics

    SciTech Connect

    Atarod, V.; Dandeno, P.L.; Iravani, M.R. (Toronto Univ., ON (Canada). Dept. of Electrical Engineering)

    1992-11-01

    This paper investigates the impact of synchronous machine parameters and second order and third order models on the phenomenon of torsional dynamics. The results were also compared with those obtained from the conventional (2d, 1q) model. For each model, the effect of rotor-field differential leakage flux on the damping of the torsional oscillations is studied. Numerical values of the elements corresponding to each model were obtained based on a parameter fitting process to a set of SSFR test results. An eigen analysis method was used for the studies. The eigen analysis results were verified by digital time domain simulation, using the Electro-Magnetic Transients Program (EMTP). The studies conclude that higher order machine model result in higher net damping for the torsional oscillations. Representation of the rotor-field differential leakage flux in the machine model reduces the torsional damping and widens the torsional range of instability with respect to the level of series compensation.

  8. Can. J. Math., Vol. XXV, No. 4,1973, pp. 712-726 ON MAXIMAL TORSION RADICALS

    E-print Network

    Beachy, John

    Can. J. Math., Vol. XXV, No. 4,1973, pp. 712-726 ON MAXIMAL TORSION RADICALS JOHN A. BEACHY Let R that if R is a commutative, Noetherian ring, then the maximal torsion radicals of R^éé correspond result valid for arbitrary commutative rings. This paper investigates maximal torsion radicals over rings

  9. Rotation-torsion analysis of the Si2H6 infrared fundamental ?, perturbed by excited torsional levels of the vibrational ground state

    NASA Astrophysics Data System (ADS)

    Lattanzi, F.; di Lauro, C.; Horneman, V.-M.

    The lowest infrared active perpendicular fundamental ?9 of disilane has been analysed on a Fourier transform spectrum between 320 and 430 cm-1, at the spectral resolution of 0.0012 cm-1. The rotation-torsion structure of this band is affected by x,y Coriolis interactions with excited torsional levels of the vibrational ground state, correlating with components of 3?4 and 4?4 in the high barrier limit. The interaction of ?9 and 4?4, forbidden in the D3d symmetry limit, is allowed between components of E torsional symmetry under the G36(EM) extended molecular group, because of the large amplitude of the internal rotation motion. We could determine the values of the main vibration-rotation-torsion parameters of ?9, interaction parameters, and the vibrational wavenumbers of the four torsional components of 3?4 and of the E3d component of 4?4. The intrinsic torsional splitting of ?9 is found to be smaller than in the ground vibrational state by 0.0066 cm-1, in good agreement with our theoretical predictions. The possibility of observing the effects of D3d-forbidden interactions in the spectra of ethane-like molecules is also discussed.

  10. Torsional oscillations of a magnetar with a tangled magnetic field

    E-print Network

    Link, Bennett

    2015-01-01

    We propose a scenario for the quasi-periodic oscillations observed in magnetar flares wherein a tangled component of the stellar magnetic field introduces nearly isotropic stress that gives the fluid core of the star an effective shear modulus. In a simple, illustrative model of constant density, the tangled field eliminates the problematic Alfv\\'en continuum that would exist in the stellar core for an organized field. For a tangled field energy density comparable to that inferred from the measured dipole fields of $\\sim 10^{15}$ G in SGRs 1806-20 and 1900+14, torsional modes exist with fundamental frequencies of about 20 Hz, and mode spacings of $\\sim 10$ Hz. For fixed stellar mass and radius, the model has only one free parameter, and can account for {\\em every} observed QPO under 160 Hz to within 3 Hz for both SGRs 1806-20 and 1900+14. The combined effects of stratification and crust stresses generally decrease the frequencies of torsional oscillations by $<10$% for overtones and increase the lowest-fre...

  11. Torsion, magnetic monopoles and Faraday's law via a variational principle

    NASA Astrophysics Data System (ADS)

    Mannheim, Philip D.

    2015-05-01

    Even though Faraday's Law is a dynamical law that describes how changing E and B fields influence each other, by introducing a vector potential A? according to F?? = ??A? – ??A? Faraday's Law is satisfied kinematically, with the relation (-g)-1/2????? ??F?? = 0 holding on every path in a variational procedure or path integral. In a space with torsion Q??? the axial vector S? = (-g)1/2?????Q??? serves as a chiral analog of A?, and via variation with respect to S? one can derive Faraday's Law dynamically as a stationarity condition. With S? serving as an axial potential one is able to introduce magnetic monopoles without S? needing to be singular or have a non-trivial topology. Our analysis permits torsion and magnetic monopoles to be intrinsically Grassmann, which could explain why they have never been detected. Our procedure permits us to both construct a Weyl geometry in which A? is metricated and then convert it into a standard Riemannian geometry.

  12. Determination of transverse shear strength through torsion testing

    SciTech Connect

    Marcucelli, K.T.; Fish, J.C. [Lockheed Martin Skunk Works, Palmdale, CA (United States)

    1997-12-31

    The in-plane characterization of composite materials is, in general, well understood and widely utilized throughout the aerospace industry. However, the use of composites in structural elements such as fuselage frames and rotorcraft flexbeams place large out-of-plane or through-the-thickness stresses for which there is little data. Efforts to determine the interlaminar shear strength of laminated composites have been hampered due to the nonlinear behavior of test specimens and the limitations of current analysis tools. An inexpensive rectangular torsion test specimen was designed to determine the interlaminar shear strength, s{sub 23}, of composite materials. Six different layups were fabricated of AS4/2220-3 carbon/epoxy unidirectional tape and tested in pure torsion. All of the specimens failed abruptly with well-defined shear cracks and exhibited linear load-deflection behavior. A quasi-three-dimensional (Q-3-D) finite element analysis was conducted on each of the specimen configurations to determine the interlaminar shear stress at failure. From this analysis, s{sub 23} was found to be 107 MPa for this material.

  13. Protective role of Proanthocyanidin in experimental ovarian torsion

    PubMed Central

    Y?ld?r?m, ?ule; Topalo?lu, Naci; Tekin, Mustafa; Küçük, Adem; Erdem, Havva; Erba?, Mesut; Y?ld?r?m, Ahmet

    2015-01-01

    Background: Proanthocyanidin is a potent bioactive antioxidant naturally occurring in grape seed and acts as reactive oxygen species (ROS) scavenger. The aim of this study was to investigate the effects of proanthocyanidinin in experimental ovarian torsion injury. Methods: Twenty four rats were randomly divided into three groups (n=8). Group 1: the laparotomy group, group 2: ovarian torsion group, and group 3: intervention group administered proanthocyanidinin of 50 mg/kg before bilateral ovarian ischemia and reperfusion. Histologic examination and scoring was done at the end of the experiment. Statistical analyses were performed using the SPSS v. 19. Results: Ovarian histopathologic findings of all three groups were significantly different in terms of hemorrhage (p<0.001), edema (p=0.001) and vascular dilatation (p< 0.001). Pathologic changes induced by I/R were reduced in ovaries of rats administered proanthocyanidin, in particular, hemorrhage, edema and vascular dilatation. Conclusion: Proanthocyanidin, known as free radical scavenger and antioxidant, is protective against tissue damage induced by ischemia and/or ischemia/reperfusion in rat ovaries.

  14. A screw theory of static beams

    Microsoft Academic Search

    J. M. Selig; X. Ding

    2001-01-01

    We derive the deflection equation of a simple beam using the screw theory. The effects of tension, torsion and bending of the beam can be unified into a single equation. We begin by looking at the compliance matrix for small elements of the beam. This is loosely based on the work by von Mises (1924). We reproduce von Mises' results

  15. Rheology of deformed Carrara marble: Insights from torsion experiments

    NASA Astrophysics Data System (ADS)

    Bruijn, R. H. C.; Delle Piane, C.; de Raadt, W. S.

    2012-04-01

    Rock deformation experiments are essential for understanding lithosphere dynamics, strain localization processes and deformation mechanisms in polymineral aggregates, as they provide rheological parameters and record fabric development of rock-forming minerals, aiding the geological interpretation of naturally deformed rocks. Carrara marble received significant attention in the rock deformation community due to its homogeneous fabric and low impurities content, making it a laboratory standard. When the torsion actuator was developed for the Paterson-type gas-medium apparatus, it became possible to perform high strain experiments and reach true steady state flow conditions in Carrara marble. At the center of these ground breakings developments stood Luigi Burlini and his students. Their work showed for the first time, the importance of fabric development on steady state flow stress in response to high strain deformation and recrystallization. In the last years of Luigi's life, he and his students took rock deformation studies to a different direction by investigating the effect of initial strain and quantifying the coupling between fabric and flow stress. We present here an overview of the four types of torsion experiment that were performed on Carrara marble with varied pre-existing strain. Earlier torsion experiments on homogeneous Carrara marble provided the framework in which these newer experiments were evaluated. In type I experiments samples were subjected to a torsion deformation leading to a maximum shear strain of 1 to 5, immediately followed by a reversed straining of equal magnitude. In type II and III experiments, a composite sample consisting of a segment of undeformed and one (type II) or two (type III) segment(s) of previously twisted Carrara marble, were deformed. In type IV experiments, a cylindrical segment of dynamically recrystallized Carrara marble was annealed 727 °C for up to five hours at to recover the original grain size without removing the developed texture. Subsequent deformation by torsion revealed the effect of initial texture on peak flow stress. Experimental conditions were designed to activate dislocation creep. Confining pressure was set at 300 MPa, temperature varied from 600 to 800 °C and the applied constant shear strain rate ranged from 3×10-4 to 1×10-3 s-1. Type I to III experiments revealed that reversed deformation recovers sheared grains, with the recovery of shape preferred orientation (SPO) requiring less strain than the recovery of crystallographic preferred orientation (CPO). They also showed that recrystallization is controlled by absolute strain rather than total strain. In terms of rheology, the first three types of experiments highlighted that strain reversal is easier than continued forward deformation (Bauschinger effect), provided sheared relict grains dominate in the fabric. Additionally, bulk sample flow behavior was shown to be dominated by the weakest segment in the composite sample. Type IV experiments quantified the weakening effect of texture at 33-67%, depending on temperature and the degree of initial CPO. All experiments showed that deformed rocks are weaker than their protolith equivalents. Therefore, despite possible alteration of shear direction, or prior grain growth, mylonites will localize strain during the next deformation event.

  16. On main conjectures in non-commutative Iwasawa theory

    E-print Network

    Bushnell, Colin J.

    1 On main conjectures in non-commutative Iwasawa theory and related conjectures David Burns Abstract. The `main conjecture of non-commutative Iwasawa theory' of Coates, Fukaya, Kato, Sujatha and Venjakob is shown to be equivalent, modulo an appropriate torsion hypothesis, to a family of main

  17. On the angular momentum of a system of quantum particles

    E-print Network

    Paris-Sud XI, Université de

    On the angular momentum of a system of quantum particles O. Chavoya-Aceves 5610 North 78th Dr, Glendale, AZ USA chavoyao@gmail.com October 3, 2013 Abstract The properties of angular momentum and its of angular momentum of a quantum system of particles into orbital angular momentum plus intrinsic angular

  18. Angular momentum and torque described with the complex octonion

    NASA Astrophysics Data System (ADS)

    Weng, Zi-Hua

    2014-08-01

    The paper aims to adopt the complex octonion to formulate the angular momentum, torque, and force etc in the electromagnetic and gravitational fields. Applying the octonionic representation enables one single definition of angular momentum (or torque, force) to combine some physics contents, which were considered to be independent of each other in the past. J. C. Maxwell used simultaneously two methods, the vector terminology and quaternion analysis, to depict the electromagnetic theory. It motivates the paper to introduce the quaternion space into the field theory, describing the physical feature of electromagnetic and gravitational fields. The spaces of electromagnetic field and of gravitational field can be chosen as the quaternion spaces, while the coordinate component of quaternion space is able to be the complex number. The quaternion space of electromagnetic field is independent of that of gravitational field. These two quaternion spaces may compose one octonion space. Contrarily, one octonion space can be separated into two subspaces, the quaternion space and S-quaternion space. In the quaternion space, it is able to infer the field potential, field strength, field source, angular momentum, torque, and force etc in the gravitational field. In the S-quaternion space, it is capable of deducing the field potential, field strength, field source, current continuity equation, and electric (or magnetic) dipolar moment etc in the electromagnetic field. The results reveal that the quaternion space is appropriate to describe the gravitational features, including the torque, force, and mass continuity equation etc. The S-quaternion space is proper to depict the electromagnetic features, including the dipolar moment and current continuity equation etc. In case the field strength is weak enough, the force and the continuity equation etc can be respectively reduced to that in the classical field theory.

  19. Non-Gaussianities in DBI inflation with angular motion

    E-print Network

    Taichi Kidani; Kazuya Koyama

    2014-10-21

    We study DBI spinflation models with angular potentials that are derived in string theory. We analyse the background dynamics with different parameter sets and study the impact of changing each parameter on inflationary dynamics. It is known that the conversion of the entropy perturbation into the curvature perturbation gives multi-field DBI inflation models a possibility of satisfying the observational constraints by relaxing the stringent microphysical constraint that disfavours single field DBI inflation models. we show that our model is excluded by the Planck satellite observations even with the conversion mechanism regardless of the parameter set.

  20. The effect of hydrogen bonding on torsional dynamics: a combined far-infrared jet and matrix isolation study of methanol dimer.

    PubMed

    Kollipost, F; Andersen, J; Mahler, D W; Heimdal, J; Heger, M; Suhm, M A; Wugt Larsen, R

    2014-11-01

    The effect of strong intermolecular hydrogen bonding on torsional degrees of freedom is investigated by far-infrared absorption spectroscopy for different methanol dimer isotopologues isolated in supersonic jet expansions or embedded in inert neon matrices at low temperatures. For the vacuum-isolated and Ne-embedded methanol dimer, the hydrogen bond OH librational mode of the donor subunit is finally observed at ~560 cm(-1), blue-shifted by more than 300 cm(-1) relative to the OH torsional fundamental of the free methanol monomer. The OH torsional mode of the acceptor embedded in neon is observed at ~286 cm(-1). The experimental findings are held against harmonic predictions from local coupled-cluster methods with single and double excitations and a perturbative treatment of triple excitations [LCCSD(T)] and anharmonic. VPT2 corrections at canonical MP2 and density functional theory (DFT) levels in order to quantify the contribution of vibrational anharmonicity for this important class of intermolecular hydrogen bond vibrational motion. PMID:25381521