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1

Static vacuum solutions of Brans-Dicke theory with torsion  

NASA Astrophysics Data System (ADS)

The static spherically symmetric solutions of the modified Brans-Dicke theory with torsion field are obtained for the vacuum case. It is shown that torsion fields are determined by the scalar field even if spin angular momentum does not exist.

Kim, Sung-Won; Cho, Byung Ha

1987-09-01

2

Analysis of One-Bond Se-Se Nuclear Couplings in Diselenides and 1,2-Diselenoles on the Basis of Molecular Orbital Theory: Torsional Angular Dependence, Electron Density Influence, and Origin in 1J(Se, Se)  

PubMed Central

Nuclear couplings for the Se-Se bonds, 1J(Se, Se), are analyzed on the basis of the molecular orbital (MO) theory. The values are calculated by employing the triple ? basis sets of the Slater type at the DFT level. 1J(Se, Se) are calculated modeled by MeSeSeMe (1a), which shows the typical torsional angular dependence on ?(CMeSeSeCMe). The dependence explains well the observed 1Jobsd (Se, Se) of small values (? 64 Hz) for RSeSeR? (1) (simple derivatives of 1a) and large values (330–380 Hz) observed for 4-substituted naphto[1,8-c, d]-1,2-diselenoles (2) which correspond to symperiplanar diselenides. 1J (Se, Se: 2) becomes larger as the electron density on Se increases. The paramagnetic spin-orbit terms contribute predominantly. The contributions are evaluated separately from each MO (?i) and each ?i ? ?a transition, where ?i and ?a are occupied and unoccupied MO's, respectively. The separate evaluation enables us to recognize and visualize the origin and the mechanism of the couplings.

Tanioku, Akito; Hayashi, Satoko; Nakanishi, Waro

2009-01-01

3

Extending modules relative to a torsion theory  

Microsoft Academic Search

An R-module M is said to be an extending module if every closed submodule of M is a direct summand. In this paper we introduce and investigate the concept of a type 2 ?-extending module, where ? is a hereditary torsion theory on Mod-R. An R-module M is called type 2 ?-extending if every type 2 ?-closed submodule of M

Semra Do?ruöz

2008-01-01

4

Feedback control of torsion balance in measurement of gravitational constant G with angular acceleration method  

NASA Astrophysics Data System (ADS)

The performance of the feedback control system is of central importance in the measurement of the Newton's gravitational constant G with angular acceleration method. In this paper, a PID (Proportion-Integration-Differentiation) feedback loop is discussed in detail. Experimental results show that, with the feedback control activated, the twist angle of the torsion balance is limited to 7.3× 10^{-7}rad/ ?{Hz} at the signal frequency of 2 mHz, which contributes a 0.4 {ppm} uncertainty to the G value.

Quan, Li-Di; Xue, Chao; Shao, Cheng-Gang; Yang, Shan-Qing; Tu, Liang-Cheng; Wang, Yong-Ji; Luo, Jun

2014-01-01

5

Dynamic Torsional Deformation Behavior of Ultra-Fine-Grained Dual-Phase Steel Fabricated by Equal Channel Angular Pressing  

NASA Astrophysics Data System (ADS)

Dynamic torsional deformation behavior of an ultra-fine-grained dual-phase steel fabricated by equal channel angular pressing (ECAP) was investigated and compared with that of an equal channel angular pressed (ECAPed) ultra-fine-grained low-carbon steel. Tensile and dynamic torsional tests were conducted on these two steels, and the deformed microstructures were observed to investigate the dynamic deformation behavior. The ECAPed low-carbon steel consisted of very fine, elongated ferrite-pearlite grains of 0.5 ?m in size, and the ECAPed dual-phase steel consisted of ferrite-martensite grains of 1 ?m in size. The dynamic torsional test results indicated that maximum shear stress of the dual-phase steel was lower than that of the conventional steel, but that fracture shear strain was higher in the dual-phase steel. Some adiabatic shear bands were observed at the gage center of the dynamically deformed torsional specimen of the low-carbon steel, but they were not observed in the dual-phase steel because localized deformation was alleviated by the increased strain hardenability. These results suggested that the ECAPed ultra-fine-grained dual-phase steel could be a good way to increase the fracture resistance under dynamic loading as the formation of adiabatic shear bands was reduced or prevented.

Hwang, Byoungchul; Kim, Yang Gon; Lee, Sunghak; Hwang, Duck Young; Shin, Dong Hyuk

2007-12-01

6

Free torsional vibration of nanotubes based on nonlocal stress theory  

NASA Astrophysics Data System (ADS)

A new elastic nonlocal stress model and analytical solutions are developed for torsional dynamic behaviors of circular nanorods/nanotubes. Unlike the previous approaches which directly substitute the nonlocal stress into the equations of motion, this new model begins with the derivation of strain energy using the nonlocal stress and by considering the nonlinear history of straining. The variational principle is applied to derive an infinite-order differential nonlocal equation of motion and the corresponding higher-order boundary conditions which contain a nonlocal nanoscale parameter. Subsequently, free torsional vibration of nanorods/nanotubes and axially moving nanorods/nanotubes are investigated in detail. Unlike the previous conclusions of reduced vibration frequency, the solutions indicate that natural frequency for free torsional vibration increases with increasing nonlocal nanoscale. Furthermore, the critical speed for torsional vibration of axially moving nanorods/nanotubes is derived and it is concluded that this critical speed is significantly influenced by the nonlocal nanoscale.

Lim, C. W.; Li, C.; Yu, J. L.

2012-06-01

7

Micromechanical torsional digital-to-analog converter for open-loop angular positioning applications  

NASA Astrophysics Data System (ADS)

This paper reports a novel micromechanical torsional digital-to-analog converter (MTDAC), operated in open-loop with digitally controlled precise multi-level tilt angles. The MTDAC mechanism presented is analogous to that of an electrical binary-weighted-input digital-to-analog converter (DAC). It consists of a rigid tunable platform, an array of torsional microactuators, each operating in a two-state (on/off) mode, and a set of connection beams with binary-weighted torsional stiffnesses that connect the actuators to the platform. The feasibility of the proposed MTDAC mechanism was verified numerically by finite element simulations and experimentally with a commercial optical phase-shifting interferometric system. A prototype 2-bit MTDAC was implemented using the poly-MUMPS process achieving a full-scale output tilt angle of 1.92° with a rotation step of 0.64°. This mechanism can be configured for many promising applications, particularly in beam steering-based OXC switches.

Zhou, Guangya; Tay, Francis E. H.; Chau, Fook Siong; Zhao, Yi; Logeeswaran, VJ

2004-05-01

8

Energy and angular momentum in generic F (Riemann) theories  

NASA Astrophysics Data System (ADS)

We construct the conserved charge of generic gravity theories built on arbitrary contractions of the Riemann tensor (but not on its derivatives) for asymptotically (anti)-de Sitter spacetimes. Our construction is a generalization of the Abbott-Deser-Tekin charges of linear and quadratic gravity theories in cosmological backgrounds. As an explicit example we find the energy and angular momentum of the Banados-Teitelboim-Zanelli black hole in the (2+1)-dimensional Born-Infeld gravity.

?entürk, Çetin; ?i?man, Tahsin Ça?r?; Tekin, Bayram

2012-12-01

9

Brans-Dicke theory of gravity with torsion: A possible solution of ?-problem  

NASA Astrophysics Data System (ADS)

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

Wu, Yu-Huei; Wang, Chih-Hung

2012-12-01

10

Scalar-Torsion Cosmology in the Poincaré Gauge Theory of Gravity  

NASA Astrophysics Data System (ADS)

We investigate the cosmological effect of the scalar-torsion (0+) mode in Poincaré gauge theory of gravity. We focus on two types of solutions distinguished by the constant curvature and kinetic energy. In the former, we find that the torsion EoS (w) varies with the background stage of the universe. In particular, it behaves like radiation (matter) of w=1/3 (w=0) in the radiation (matter) dominant era. But eventually in the late time the torsion density becomes a de Sitter universe for the acceleration universe. In the latter, our numerical analysis indicates that the EoS has an asymptotic behavior in the high redshift regime. We also employ theoretical calculations together with numerical computations in accordance with such asymptotic phenomenon.

Geng, Chao-Qiang; Lee, Chung-Chi; Tseng, Huan-Hsin

2014-01-01

11

Importance of torsion and invariant volumes in Palatini theories of gravity  

NASA Astrophysics Data System (ADS)

We study the field equations of extensions of general relativity formulated within a metric-affine formalism setting torsion to zero (Palatini approach). We find that different (second-order) dynamical equations arise depending on whether torsion is set to zero (i) a priori or (ii) a posteriori, i.e., before or after considering variations of the action. Considering a generic family of Ricci-squared theories, we show that in both cases the connection can be decomposed as the sum of a Levi-Cività connection and terms depending on a vector field. However, while in case (i) this vector field is related to the symmetric part of the connection, in (ii) it comes from the torsion part and, therefore, it vanishes once torsion is completely removed. Moreover, the vanishing of this torsion-related vector field immediately implies the vanishing of the antisymmetric part of the Ricci tensor, which therefore plays no role in the dynamics. Related to this, we find that the Levi-Cività part of the connection is due to the existence of an invariant volume associated with an auxiliary metric h??, which is algebraically related with the physical metric g??.

Olmo, Gonzalo J.; Rubiera-Garcia, D.

2013-10-01

12

Angular Accelerometer.  

National Technical Information Service (NTIS)

An angular accelerometer with a blade damper on a torsion arm was examined. A comparative evaluation was conducted with a conventional inertia angular accelerometer for sensitivity. Relationships for parameter selection are given. The possibility of obtai...

V. M. Subbotin

1972-01-01

13

Observational information for f(T) theories and dark torsion  

NASA Astrophysics Data System (ADS)

In the present work we analyze and compare the information coming from different observational data sets in the context of a sort of f(T) theories. We perform a joint analysis with measurements of the most recent type Ia supernovae (SNe Ia), Baryon Acoustic Oscillation (BAO), Cosmic Microwave Background radiation (CMB), Gamma-Ray Bursts data (GRBs) and Hubble parameter observations (OHD) to constraint the only new parameter these theories have. It is shown that when the new combined BAO/CMB parameter is used to put constraints, the result is different from previous works. We also show that when we include Observational Hubble Data (OHD) the simpler ?CDM model is excluded to one sigma level, leading the effective equation of state of these theories to be of phantom type. Also, analyzing a tension criterion for SNe Ia and other observational sets, we obtain more consistent and better suited data sets to work with these theories.

Bengochea, Gabriel R.

2011-01-01

14

Theory Of Accretion Disks I: Angular Momentum Transport Processes  

NASA Astrophysics Data System (ADS)

Accretion disk flow is a common phenomenon in astrophysics. It provides the nursery for planetary system formation and the channel for mass transfer in interacting binary stars. Such flows are also associated with the central engine for active galactic nuclei. Mass is redistributed in accretion disks as a consequence of angular momentum transfer. The identification of the dominant process involved is an important task in the development of accretion disk theory. Here, we review recent theoretical investigations on several important physical processes, including: 1. the removal of angular momentum from disks through hydromagnetic winds, 2. the amplification of local viscous stress through the onset of turbulence resulting from possible hydromagnetic, convective, or shear flow instabilities, 3. the transport of angular momentum carried by propagating waves, and 4. torque resulting from the presence of nonaxisymmetric unstable modes in self-gravitating and geometrically thick disks. Because of the technical nature of this subject, we present some of the mathematical formalisms in a pedagogical manner. We focus our attention on the physical discussion of the necessary conditions for each process to operate and the efficiency of angular momentum transfer to be expected. In Part II of this review, we shall present observational evidences and discuss applications of theoretical results in different astrophysical contexts.

Papaloizou, J. C. B.; Lin, D. N. C.

15

Scalar-tensor theory in higher-dimensional space-time with torsion  

SciTech Connect

The modified Brans-Dicke theory with a torsion field is discussed in five-dimensional space of Kaluza-Klein type. It is shown that the electromagnetic field and the scalar field appear during the reduction of five-dimensional action. A conformally mapped metric is also used to see the relation between the scalar field and the tlaplon field which is induced for the electromagnetic field to be invariant under the gauge transformation and their equivalence.

Kim, S.; Cho, B.H.

1987-10-15

16

Gyrokinetic theory and simulation of angular momentum transport  

SciTech Connect

A gyrokinetic theory of turbulent toroidal angular momentum transport as well as modifications to neoclassical poloidal rotation from turbulence is formulated starting from the fundamental six-dimensional kinetic equation. The gyro-Bohm scaled transport is evaluated from toroidal delta-f gyrokinetic simulations using the GYRO code [Candy and Waltz, J. Comput. Phys. 186, 545 (2003)]. The simulations recover two pinch mechanisms in the radial transport of toroidal angular momentum: The slab geometry ExB shear pinch [Dominguez and Staebler, Phys. Fluids B 5, 387 (1993)] and the toroidal geometry 'Coriolis' pinch [Peeters, Angioni, and Strintzi, Phys. Rev. Lett. 98, 265003 (2007)]. The pinches allow the steady state null stress (or angular momentum transport flow) condition required to understand intrinsic (or spontaneous) toroidal rotation in heated tokamak without an internal source of torque [Staebler, Kinsey, and Waltz, Bull. Am. Phys. Soc. 46, 221 (2001)]. A predicted turbulent shift in the neoclassical poloidal rotation [Staebler, Phys. Plasmas 11, 1064 (2004)] appears to be small at the finite relative gyroradius (rho-star) of current experiments.

Waltz, R. E.; Staebler, G. M.; Candy, J.; Hinton, F. L. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)

2007-12-15

17

Torsional broadening in absorption and emission spectra of bithiophene as calculated by time-dependent density functional theory  

NASA Astrophysics Data System (ADS)

The optimized geometries of bithiophene in the electronic ground and excited state have been calculated by time-dependent density functional theory using the hybrid functional B3-LYP. The dependence of the singlet excitation energies and transition dipoles on the torsion between the two thienyl groups has been determined and compared with the torsional potential curve previously found for biphenyl. Based on these data the torsional progressions in absorption and emission have been computed quantum-mechanically in order to show their contribution to the inhomogeneous broadening in the respective spectra of bithiophene.

Beenken, Wichard J. D.

2008-06-01

18

Non-uniform warping including the effects of torsion and shear forces. Part I: A general beam theory  

Microsoft Academic Search

This two-part contribution presents a beam theory with a non-uniform warping including the effects of torsion and shear forces, and valid for any homogeneous cross-section made of isotropic elastic material. Part I is devoted to the theoretical developments and part II discusses analytical and numerical results obtained for torsion and shear-bending of cantilever beams made of different kinds of cross-section.

Rached El Fatmi

2007-01-01

19

Angular-momentum-dependent orbital-free density functional theory.  

PubMed

Orbital-free (OF) density functional theory (DFT) directly solves for the electron density rather than the wave function of many electron systems, greatly simplifying and enabling large scale first principles simulations. However, the required approximate noninteracting kinetic energy density functionals and local electron-ion pseudopotentials severely restrict the general applicability of conventional OFDFT. Here, we present a new generation of OFDFT called angular-momentum-dependent (AMD)-OFDFT to harness the accuracy of Kohn-Sham DFT and the simplicity of OFDFT. The angular momenta of electrons are explicitly introduced within atom-centered spheres so that the important ionic core region can be accurately described. In addition to conventional OF total energy functionals, we introduce a crucial nonlocal energy term with a set of AMD energies to correct errors due to the kinetic energy density functional and the local pseudopotential. We find that our AMD-OFDFT formalism offers substantial improvements over conventional OFDFT, as we show for various properties of the transition metal titanium. PMID:23971595

Ke, Youqi; Libisch, Florian; Xia, Junchao; Wang, Lin-Wang; Carter, Emily A

2013-08-01

20

Angular Momentum Dependent Orbital Free Density Functional Theory  

NASA Astrophysics Data System (ADS)

We report a novel and general formalism for linear scaling, angular momentum dependent (AMD) orbital free (OF) density functional theory (DFT) to advance the accuracy and applicability of OFDFT. To introduce angular momentum dependence in OFDFT, we devise a hybrid scheme by partitioning the system into muffin-tin spheres and an interstitial region: the electron density inside the spheres is expressed by a set of Kohn-Sham (KS) DFT derived atom-centered basis functions combined with an on-site density matrix NR. A general OFDFT total energy functional is introduced with a crucial nonlocal energy term E^NL which is neglected in conventional implementations of OFDFT. E^NL corrects the errors due to the use of approximate kinetic energy density functionals and local pseudopotentials for ion-electron interactions. We approximate E^NL to include AMD contributions inside the spheres: as a first step, a linear dependence on the NR is considered with a set of AMD energies E^lR. E^lR are determined by fitting a small set of bulk properties to KSDFT. We find AMD-OFDFT offers substantial improvements over conventional OFDFT, as we show for various properties of the transition metal Ti and its alloys (TixAl1-x).

Ke, Youqi; Libisch, Florian; Xia, Junchao; Wang, Lin-Wang; Carter, Emily A.

2013-03-01

21

Singularity in the Laboratory Frame Angular Distribution Derived in Two-Body Scattering Theory  

ERIC Educational Resources Information Center

The laboratory (lab) frame angular distribution derived in two-body scattering theory exhibits a singularity at the maximum lab scattering angle. The singularity appears in the kinematic factor that transforms the centre of momentum (cm) angular distribution to the lab angular distribution. We show that it is caused in the transformation by the…

Dick, Frank; Norbury, John W.

2009-01-01

22

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

SciTech Connect

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.

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

23

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

Microsoft Academic Search

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 $\\\

Thomas Friedrich; Stefan Ivanov

2001-01-01

24

Theory of pure rotational transitions in doubly degenerate torsional states of ethane  

NASA Technical Reports Server (NTRS)

It is shown that pure rotational transitions in doubly degenerate torsional states of C2H6 (with selection rules Delta K = 0, plus or minus 1) are made allowed by Coriolis interaction between torsion and dipole-allowed vibrations. Expressions are presented for integrated intensities from which strengths of lines in the millimeter region can be calculated.

Rosenberg, A.; Susskind, J.

1979-01-01

25

Angular correlation between photoelectrons and Auger electrons within scattering theory  

SciTech Connect

In this paper we present a single-particle scattering approach for the angular correlation between a photoelectron and the subsequent Auger electron from atomic targets. This method is proposed as an alternative approach with respect to the usual density matrix formalism, since it is more convenient for extension to the solid state case. Such an extension is required by the great progress made in the field of coincidence spectroscopy in condensed matter systems. We derived a tensor expression for the cross section and an equivalent expression in terms of convenient angular functions has been treated for the case of linearly polarized light. Numerical calculations are performed for the L{sub 3}M{sub 2,3}M{sub 2,3} transition in argon, in the single configuration Dirac-Fock scheme. Results are compared with experimental data for different final angular momentum states of the doubly charged ion and for different kinematical conditions.

Da Pieve, F.; Stefani, G. [Physics Department, University Roma Tre and CNISM, via della Vasca Navale 84, I-00146 Rome (Italy); Di Matteo, S.; Natoli, C. R. [INFN Laboratori Nazionali di Frascati, via Enrico Fermi 40, I-00044 Frascati (Italy); Sebilleau, D. [Equipe de Physique des Surfaces et des Interfaces, Laboratoire de Physique des Atomes, Lasers, Molecules et Surfaces, UMR CNRS-Universite 6627, Universite de Rennes 1, 35042 Rennes Cedex (France); Gunnella, R. [Physics Department, University of Camerino, Via Madonna delle Carceri, I-62032 Camerino (Italy)

2007-05-15

26

Theory for Noise of Propellers in Angular Inflow with Parametric Studies and Experimental Verification.  

National Technical Information Service (NTIS)

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 ...

D. B. Hanson D. J. Parzych

1993-01-01

27

Three-dimensional angular momentum projection in relativistic mean-field theory  

Microsoft Academic Search

Based on a relativistic mean-field theory with an effective point coupling between the nucleons, three-dimensional angular momentum projection is implemented for the first time to project out states with designed angular momentum from deformed intrinsic states generated by triaxial quadrupole constraints. The same effective parameter set PC-F1 of the effective interaction is used for deriving the mean field and the

J. M. Yao; J. Meng; P. Ring; D. Pena Arteaga

2009-01-01

28

Torsional vibration of carbon nanotube-buckyball systems based on nonlocal elasticity theory  

NASA Astrophysics Data System (ADS)

In this paper, torsional vibration analysis of single-walled carbon nanotube-buckyball systems is carried out. The buckyball is attached to single-walled carbon nanotube (SWCNT) at one end and the other end of SWCNT is fixed. Such nanostructures are promising for tunable nanoresonators whose frequency can be altered by attaching different buckyballs. Nonlocal elasticity is utilized to examine the small-scale effect on the nanoresonators and derive the torsional frequency equation and nonlocal transcendental equation. Based on these equations, numerical results are obtained for the dependence of the frequency on the mass moment of inertia. The analytical expressions of nonlocal frequencies are also derived when the buckyballs mass moment of inertias are much larger than that of SWCNTs. In addition, effort is made to study the influence of nonlocal parameter and attached buckyball on the torsional frequency of the nanoresonators.

Murmu, T.; Adhikari, S.; Wang, C. Y.

2011-04-01

29

Generalization of Equivalent Crystal Theory to Include Angular Dependence  

NASA Technical Reports Server (NTRS)

In the original Equivalent Crystal Theory, each atomic site in the real crystal is assigned an equivalent lattice constant, in general different from the ground state one. This parameter corresponds to a local compression or expansion of the lattice. The basic method considers these volumetric transformations and, in addition, introduces the possibility that the reference lattice is anisotropically distorted. These distortions however, were introduced ad-hoc. In this work, we generalize the original Equivalent Crystal Theory by systematically introducing site-dependent directional distortions of the lattice, whose corresponding distortions account for the dependence of the energy on anisotropic local density variations. This is done in the spirit of the original framework, but including a gradient term in the density. This approach is introduced to correct a deficiency in the original Equivalent Crystal Theory and other semiempirical methods in quantitatively obtaining the correct ratios of the surface energies of low index planes of cubic metals (100), (110), and (111). We develop here the basic framework, and apply it to the calculation of Fe (110) and Fe (111) surface energy formation. The results, compared with first principles calculations, show an improvement over previous semiempirical approaches.

Ferrante, John; Zypman, Fredy R.

2004-01-01

30

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

SciTech Connect

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.

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

31

Unexpectedly low angular extent of journal bearing pressures: experiment and theory  

NASA Astrophysics Data System (ADS)

Journal bearings have been studied for a long time. Pressure solutions for the same, as presented in textbooks, typically have angular extents exceeding 150°. Here, for a bearing with a relatively larger clearance ratio (0.01 as opposed to, say, 0.001), our experiments show an angular extent of about 50° only. Such small angular extents cannot be predicted, even approximately, by the existing simple theories for journal bearing pressures. However, such theories are based on assumptions whereby only the relative speed between bearing and journal surfaces enters the governing equations. We discuss how these same assumptions motivate some new combinations of boundary conditions that allow reasonably simple numerical treatment. In this paper, the resulting families of possible solutions are computed semi-numerically using a Fourier series expansion in one direction and finite differences and numerical continuation in the other. We find that one such solution family contains small-extent solutions similar to those observed experimentally.

Sharma, Nikhil; Vimal, T.; Chatterjee, Anindya

2014-03-01

32

Higher dimensional Brans-Dicke theory.  

NASA Astrophysics Data System (ADS)

The modified Brans-Dicke theory with the torsion field is discussed in six-dimensional space and the static spherically symmetric solutions are obtained for the vacuum case assuming that the torsion field is generated by only extra dimensional spin angular momentum and scalar field. It is shown that the extra dimensional intrinsic spin predicts the extra components of energy-momentum tensor.

Kim, S. W.; Cho, B. H.

33

Dangerous angular Kaluza-Klein/glueball relics in string theory cosmology  

SciTech Connect

The presence of Kaluza-Klein (KK) particles in the universe is a potential manifestation of string theory cosmology. In general, they can be present in the high temperature bath of the early universe. In particular examples, string theory inflation often ends with brane-antibrane annihilation followed by the energy cascading through massive closed string loops to KK modes which then decay into lighter standard model particles. However, massive KK modes in the early universe may become dangerous cosmological relics if the inner manifold contains warped throat(s) with approximate isometries. In the complimentary picture, in the AdS/CFT dual gauge theory with extra isometries, massive glueballs of various spins become the dangerous cosmological relics. The decay of these angular KK modes/glueballs, located around the tip of the throat, is caused by isometry breaking which results from gluing the throat to the compact Calabi-Yau (CY) manifold. We address the problem of these angular KK particles/glueballs, studying their interactions and decay channels, from the theory side, and the resulting cosmological constraints on the warped compactification parameters, from the phenomenology side. The abundance and decay time of the long-lived nonrelativistic angular KK modes depend strongly on the parameters of the warped geometry, so that observational constraints rule out a significant fraction of the parameter space. In particular, the coupling of the angular KK particles can be weaker than gravitational.

Dufaux, J. F. [Instituto de Fisica Teorica UAM/CSIC, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); CITA, University of Toronto, 60 St. George st., Toronto, ON M5S 3H8 (Canada); Kofman, L. [CITA, University of Toronto, 60 St. George st., Toronto, ON M5S 3H8 (Canada); Peloso, M. [School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

2008-07-15

34

Torsional vibration of carbon nanotube–buckyball systems based on nonlocal elasticity theory  

Microsoft Academic Search

In this paper, torsional vibration analysis of single-walled carbon nanotube–buckyball systems is carried out. The buckyball is attached to single-walled carbon nanotube (SWCNT) at one end and the other end of SWCNT is fixed. Such nanostructures are promising for tunable nanoresonators whose frequency can be altered by attaching different buckyballs. Nonlocal elasticity is utilized to examine the small-scale effect on

T. Murmu; S. Adhikari; C. Y. Wang

2011-01-01

35

Torsional vibrational modes of (HF)3: IR–IR double resonance spectroscopy and electrical interaction theory  

Microsoft Academic Search

A concerted theoretical and experimental effort has been carried out to characterize and assign in-plane and out-of-plane torsional vibrational modes of hydrogen fluoride trimer. These vibrations are large amplitude motions which sample sizable regions of the intermolecular potential energy surface. The cyclic (HF)3 cluster was modeled as a three-dimensional system of fully coupled hindered rotors. Vibrational energy levels, wave functions,

Kirk D. Kolenbrander; Clifford E. Dykstra; James M. Lisy

1988-01-01

36

Omental torsion  

PubMed Central

Omental torsion is a rare cause of acute abdominal pain, and clinically mimics acute appendicitis. A 11-year-old boy presented with symptoms and signs suggestive of appendicitis. A computed tomography of abdomen revealed findings suggestive of omental torsion. Diagnostic laparoscopy confirmed the diagnosis of torsion of a segment of the greater omentum.

Jain, Paresh; Chhabra, Sheri; Parikh, Ketan; Vaidya, Amrish

2008-01-01

37

Propagating torsion in the Einstein frame  

SciTech Connect

The Einstein-Cartan-Saa theory of torsion modifies the spacetime volume element so that it is compatible with the connection. The condition of connection compatibility gives constraints on torsion, which are also necessary for the consistence of torsion, minimal coupling, and electromagnetic gauge invariance. To solve the problem of positivity of energy associated with the torsionic scalar, we reformulate this theory in the Einstein conformal frame. In the presence of the electromagnetic field, we obtain the Hojman-Rosenbaum-Ryan-Shepley theory of propagating torsion with a different factor in the torsionic kinetic term.

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

2006-11-15

38

On Poincaré gauge theory of gravity, its equations of motion, and Gravity Probe B  

NASA Astrophysics Data System (ADS)

We discuss the structure of the Poincaré gauge theory of gravity (PG) that can be considered as the standard theory of gravity with torsion. We reconfirm that torsion, in the context of PG, couples only to the elementary particle spin and under no circumstances to the orbital angular momentum of test particles. We conclude that, unfortunately, the investigations of Mao et al. (2007) and March et al. (2011)-who claimed a coupling of torsion to orbital angular momentum, in particular in the context of the Gravity Probe B (GPB) experiment-do not yield any information on torsion.

Hehl, Friedrich W.; Obukhov, Yuri N.; Puetzfeld, Dirk

2013-10-01

39

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

NASA Astrophysics Data System (ADS)

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 ?.

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

2013-08-01

40

Time-dependent theory of angular correlations in sequential double ionization.  

PubMed

In this work, we emphasize the importance of the bound-state dynamics to the two-electron ejection in double ionization processes. The conclusions of the present study are pertinent to all excitation or decay processes that proceed via well-defined intermediate states. A general strong-field time-dependent density matrix theory is established and applied to the case of neon, allowing us to analyze the role of the ionizing field in the interpretation of reported angular patterns [M. Kurka et al., J. Phys. B 42, 141002 (2009); A.?S. Kheifets, J. Phys. B 42, 134016 (2009)] and in the dynamic ionic alignment. The present analysis reveals that short-pulse coherent excitation of the neon ionic doublet 2P(1/2,3/2) leads to quantum beats in the two-electron angular correlation patterns. PMID:24033028

Nikolopoulos, L A A

2013-08-30

41

Nearside-farside theory of elastic angular scattering for strongly absorptive collisions  

NASA Astrophysics Data System (ADS)

A systematic investigation has been made of ways for combining the method of Yennie, Ravenhall and Wilson (YRW) for the resummation of a partial wave Legendre series with the nearside-farside (NF) angular decompositions of Fuller and Hatchell. Of the resulting four procedures, the most useful one first applies the YRW resummation method m times (m = 0,1,2,. . .) to the partial wave scattering amplitude, followed by the Fuller NF decomposition. This NF procedure performs best for the physical interpretation of structure in the angular scattering of strongly absorptive elastic collisions. Numerical results from all four NF procedures are reported for a partial wave series possessing a simple parametrized scattering matrix element. The theory and calculations are relevant to atom-atom and atom-molecule elastic scattering in the presence of other open channels, for example, chemical reaction.

Hollifield, J. J.; Connor, J. N. L.

42

Statistical electron angular correlation coefficients for atoms within the Hohenberg-Kohn-Sham theory  

SciTech Connect

Statistical electron angular correlation coefficients tau = 2 < summation/sup /, have been obtained for the atomic systems /sub 2/He through /sub 14/Si, within the Hohenberg-Kohn-Sham density-functional formalism. These are computed with use of the spectral sum rules obtained from the pseudoexcitation spectrum employing the recent formulation of the time-dependent Kohn-Sham theory due to Bartolotti. Various approximations to the exchange-correlation energy functional are used and for first-row atoms, a comparison is made with the highly accurate correlation coefficients recently obtained by Thakkar. The present tau values show closer agreement with those of Thakkar with increasing number of electrons.

Pathak, R.K.

1985-05-01

43

Multistructural variational transition state theory: kinetics of the hydrogen abstraction from carbon-2 of 2-methyl-1-propanol by hydroperoxyl radical including all structures and torsional anharmonicity.  

PubMed

We calculated the forward and reverse rate constants of the hydrogen abstraction reaction from carbon-2 of 2-methyl-1-propanol by hydroperoxyl radical over the temperature range 250-2400 K by using multistructural canonical variational transition state theory (MS-CVT) including both multiple-structure and torsional potential anharmonicity effects by the multistructural torsional anharmonicity (MS-T) method. In these calculations, multidimensional tunneling (MT) probabilities used to compute the tunneling transmission coefficients were evaluated by the small-curvature tunneling (SCT) approximation. Comparison with the rate constants obtained by the single-structural harmonic oscillator (SS-HO) approximation shows that multistructural anharmonicity increases the forward rate constants for all temperatures, but the reverse rate constants are reduced for temperatures lower than 430 K and increased for higher temperatures. The neglect of multistructural torsional anharmonicity would lead to errors of factors of 1.5, 8.8, and 13 at 300, 1000, and 2400 K, respectively, for the forward reaction, and would lead to errors of factors of 0.76, 3.0, and 6.0, respectively, at these temperatures for the reverse reaction. PMID:23020791

Xu, Xuefei; Yu, Tao; Papajak, Ewa; Truhlar, Donald G

2012-11-01

44

Accounting for conformational flexibility and torsional anharmonicity in the H + CH3CH2OH hydrogen abstraction reactions: A multi-path variational transition state theory study  

NASA Astrophysics Data System (ADS)

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.

Meana-Pañeda, Rubén; Fernández-Ramos, Antonio

2014-05-01

45

Approximation of the theory of stochastic perturbations of angular correlations for fluctuating distributions of electric quadrupole interactions  

Microsoft Academic Search

The perturbation of angular correlations by a fluctuating distribution of electric quadrupole interactions has been calculated with Blume's stochastic theory for an ensemble of 10 states differing in magnitude and orientation of an electric field gradient as a function of the fluctuation rate w for different values of the fluctuating and the static components of the distribution. By fits to

M. Forker; W. Herz; D. Simon

1994-01-01

46

Alternating torsions in a living '9 + 2' flagellum  

PubMed Central

Live spermatozoa of the Japanese quail were observed as they swam in highly viscous salines. Under these conditions, torsions of the flagellum were readily seen. The torsions had a characteristic magnitude (nominally 180 degrees) and pattern of incidence. As a cycle of bending propagated over it, each position on the flagellum experienced first a sinistral torsion and, later, a restoring dextral torsion. The two zones of torsion were each associated with bending; between them was a torsion-free zone that tended to be straight. The amount of interdoublet sliding needed to generate the torsions may be as little as 10 nm. These dynamic propagating torsions have been detected by following the angular displacements of individual (swollen) mitochondria lying adjacent to the axoneme. It is suggested that torque generation is a primary outcome when the unconstrained '9 + 2' axoneme is activated.

Woolley, D. M.; Vernon, G. G.

1999-01-01

47

Bellows joint absorbs torsional deflections in duct system  

NASA Technical Reports Server (NTRS)

Long, thin-walled bellows compressed into a short length absorbs the same amount of torsional deflection as the same tube in full length condition and saves in cost, complexity and space. This bellows has lower torsional spring rate to absorb the bulk of the duct assembly tortional deflections, leaving the other bellows free to absorb axial and angular deflections.

Daniels, C. M.

1966-01-01

48

Theory of Angular and Polarization Correlation in Tandem Two-Photon Processes: Application to Photoselection  

Microsoft Academic Search

To facilitate the interpretation of photoselection and photochemical experiments that depend on light intensity, generalized intensity distribution and polarization correlation formulas are derived. These are expressed in terms of Euler angles and multipole transition moments taking into account (1) molecular multipole radiation up to any order, inclusive of their coherent interference, (2) angular distribution of radiation for a given polarization,

Ying-Nan Chiu

1968-01-01

49

Torsion and the gravitational interaction  

NASA Astrophysics Data System (ADS)

By using a nonholonomous-frame formulation of the general covariance principle, seen as an active version of the strong equivalence principle, an analysis of the gravitational coupling prescription in the presence of curvature and torsion is made. The coupling prescription implied by this principle is found to be always equivalent to that of general relativity, a result that reinforces the completeness of this theory, as well as the teleparallel point of view according to which torsion does not represent additional degrees of freedom for gravity, but simply an alternative way of representing the gravitational field.

Arcos, H. I.; Pereira, J. G.

2004-11-01

50

Thermoelastic damping in torsion microresonators with coupling effect between torsion and bending  

NASA Astrophysics Data System (ADS)

Predicting thermoelastic damping (TED) is crucial in the design of high Q MEMS resonators. In the past, there have been few works on analytical modeling of thermoelastic damping in torsion microresonators. This could be related to the assumption of pure torsional mode for the supporting beams in the torsion devices. The pure torsional modes of rectangular supporting beams involve no local volume change, and therefore, they do not suffer any thermoelastic loss. However, the coupled motion of torsion and bending usually exists in the torsion microresonator when it is not excited by pure torque. The bending component of the coupled motion causes flexural vibrations of supporting beams which may result in significant thermoelastic damping for the microresonator. This paper presents an analytical model for thermoelastic damping in torsion microresonators with the coupling effect between torsion and bending. The theory derives a dynamic model for torsion microresonators considering the coupling effect, and approximates the thermoelastic damping by assuming the energy loss to occur only in supporting beams of flexural vibrations. The thermoelastic damping obtained by the present model is compared to the measured internal friction of single paddle oscillators. It is found that thermoelastic damping contributes significantly to internal friction for the case of the higher modes at room temperature. The present model is validated by comparing its results with the finite-element method (FEM) solutions. The effects of structural dimensions and other parameters on thermoelastic damping are investigated for the representative case of torsion microresonators.

Tai, Yongpeng; Li, Pu; Fang, Yuming

2014-02-01

51

Study on torsional fretting behavior of UHMWPE  

NASA Astrophysics Data System (ADS)

Torsional fretting tests of UHMWPE against titanium alloy ball (TC4) had been carried out. A frictional torque-angular displacement ( T- ?) curve was used to analyze the kinetics behaviors of torsional fretting mode. The wear morphology and damage mechanisms of UHMWPE were studied based on examinations by scanning electron microscopy (SEM). It is found that the contact stiffness and friction-dissipated energy initially rise and then gradually reach a steady state. The worn surface is characterized by adhesion in the centre zone, while in the outer annulus, ripples, ploughs and delamination appeared. In addition, a transfer film is found on the surface of titanium alloy ball.

Yu, Jia; Cai, Zhenbing; Zhu, Minhao; Qu, Shuxin; Zhou, Zhongrong

2008-11-01

52

Nonlinear Theory and Angular Spectrum of the Ion-acoustic Instability.  

National Technical Information Service (NTIS)

A nonlinear theory of the current-driven ion-acoustic instability is presented. The saturation mechanism is the perturbation of the ion orbits by the turbulent waves, which results in a broadening of the resonant interaction between the ions and the waves...

A. M. Sleeper J. Weinstock B. Bezzerides

1973-01-01

53

Pendulum Micromechanical Angular Accelerometer with Force Feedback  

Microsoft Academic Search

This paper bring forward a kind of pendulum micromechanical angular accelerometer with force feedback, which might be proposed by us, first. The sensor adopts a pendulum with mass joined to the anchors by a pair torsion-spring beams as sensing device, differential-capacitor device for detecting the angular acceleration about the X axis, an electrostatic force device for feedback loop. The sensor's

Li Jianli; Fang Jiancheng; Sheng Wei

2007-01-01

54

Stress singularities at angular corners in first-order shear deformation plate theory  

Microsoft Academic Search

The first-known Williams-type singularities caused by homogeneous boundary conditions in the first-order shear deformation plate theory (FSDPT) are thoroughly examined. An eigenfunction expansion method is used to solve the three equilibrium equations in terms of displacement components. Asymptotic solutions for both moment singularity and shear-force singularity are developed. The characteristic equations for moment singularity and shear-force singularity and the corresponding

C. S Huang

2003-01-01

55

Excitation and dissipation of torsional modes in solar photospheric magnetic flux tubes  

Microsoft Academic Search

The turbulent excitation of torsional Alfvén waves is presented on the basis of Lighthill-Stein theory. Due to the special properties of torsional modes, we can apply the theory to the inhomogeneous magnetic flux tube embedded in the solar photosphere, to evaluate the wave energy generated from the turbulent source in the convection zone. Torsional wave spectrum distribution along the r

Q. Y. Luo; F. S. Wei; X. S. Feng

2002-01-01

56

Rotating Torsion Balance Tests of the Equivalence Principle  

NASA Astrophysics Data System (ADS)

We present current results from tests of the equivalence principle using a rotating torsion balance. Test bodies made from different materials are arranged in a composition dipole and installed on a torsion pendulum. The torsion pendulum is mounted on a turntable that rotates with constant angular velocity. Test body pairs of Be-Ti, Be-Al and test bodies that mimic the earth's and moon's compositions were used. Results are presented with limits using the earth and astrophysical objects as sources for a hypothetical equivalence principle violation. )

Wagner, Todd; Schlamminger, Stephan; Gundlach, Jens

2010-02-01

57

[Ultrasound in testicular torsion].  

PubMed

Thirty-two patients were evaluated by scrotal ultrasound prior to examination due to testicular torsion. Typical ultrasonographic patterns of testicular torsion were obtained in 100% within the first 6 hours, 25% between 6-12 hours, and 91.6% after 12 hours; the overall percentage was 84.4% for all cases. PMID:8720999

Granados, E A; Martí, J; de la Torre, P

1996-01-01

58

TORSIONAL AND BENDING VIBRATION MEASUREMENT ON ROTORS USING LASER TECHNOLOGY  

Microsoft Academic Search

Based on the principles of laser Doppler velocimetry, the laser torsional vibrometer (LTV) was developed for non-contact measurement of torsional oscillation of rotating shafts, offering significant advantages over conventional techniques. This paper describes comprehensive theory to account for the sensitivity of the LTV's measurements to shaft motion in all degrees of freedom. The optical geometry of the LTV offers inherent

T. J MILES; M LUCAS; N. A HALLIWELL; S. J ROTHBERG

1999-01-01

59

Torsion and Particle Horizons  

NASA Astrophysics Data System (ADS)

Inthe present work we show that the existence of non-vanishing torsion field may solve, at least, one of the problems FRW-cosmology, the particle horizons problem. The field equations of general relativity (GR) are written in a space having non-vanishing torsion, the absolute parallelism (AP) space. An AP-Structure, satisfying the cosmological principle, is used to construct a world model. Energy density and pressure, purely induced by torsion, are defined from the building blocks of the AP-geometry using GR. When these quantities are used in the FRW-dynamical equations, we get a world model free from particle horizons.

Wanas, M. I.; Hassan, H. A.

2014-04-01

60

Torsion pendulum revisited  

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

61

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

SciTech Connect

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.

Clark, G

2003-04-28

62

Torsional motions in methyl glycolate  

NASA Astrophysics Data System (ADS)

Microwave spectra of the ground state and nine torsionally excited states and the far-infrared spectrum of methyl glycolate are reported and analyzed in terms of a flexible model involving the methyl and two skeletal torsional modes. The shifts of methyl torsional A-state rotational constants relative to the ground state observed for a series of torsionally excited states, the methyl torsional A- E splittings for the ground state and five torsionally excited states, and 10 observed skeletal torsional far-infrared transition frequencies have been used to derive three structural relaxation parameters and nine potential energy parameters. As an unexpected nonlocal interaction, a sizable coupling has been obtained between the methyl torsion and the torsion about the C?C bond, which changes the direction of the intramolecular hydrogen bond.

Meyer, R.; Caminati, W.; Hollenstein, H.

1989-09-01

63

Angular Cheilitis  

MedlinePLUS

... of angular cheilitis is usually undertaken with topical antifungals such as nystatin, clotrimazole, or econazole. Combinations of a topical antifungal and a topical steroid – such as Mycostatin® and ...

64

Experimental bounds on the coupling of massless spin-1 torsion  

Microsoft Academic Search

Agreement of reactor neutrino data with Weinberg-Salam neutral-current theory is shown to imply (gT24pi)<10-10, where gT is the coupling of a massless spin-1 torsion multiplet to fermions. If one demands that emission of massless spin-1 torsion quanta not destroy the energy balance inside helium-burning stars, one obtains a stronger limit (gT24pi)<10-34. This bound is extremely strict, yet a torsion-balance experiment

Donald E. Neville

1982-01-01

65

Experimental bounds on the coupling of massless spin-1 torsion  

NASA Astrophysics Data System (ADS)

Agreement of reactor neutrino data with Weinberg-Salam neutral-current theory is shown to imply (gT24?)<10-10, where gT is the coupling of a massless spin-1 torsion multiplet to fermions. If one demands that emission of massless spin-1 torsion quanta not destroy the energy balance inside helium-burning stars, one obtains a stronger limit (gT24?)<10-34. This bound is extremely strict, yet a torsion-balance experiment recently suggested by Newman should be able to improve even this bound by several orders of magnitude.

Neville, Donald E.

1982-01-01

66

Torsional oscillations of slowly rotating relativistic stars  

NASA Astrophysics Data System (ADS)

We study the effects of rotation on the torsional modes of oscillating relativistic stars with a solid crust. Earlier works in Newtonian theory provided estimates of the rotational corrections for the torsional modes and suggested that they should become Chandrasekhar-Friedman-Schutz unstable, even for quite low rotation rates. In this work, we study the effect of rotation in the context of general relativity using elasticity theory and in the slow-rotation approximation. We find that the Newtonian picture does not change considerably. The inclusion of relativistic effects leads only to quantitative corrections. The degeneracy of modes for different values of m is removed, and modes with l = m are shifted towards zero frequencies and become secularly unstable at stellar rotational frequencies ~20-30 Hz.

Vavoulidis, M.; Stavridis, A.; Kokkotas, K. D.; Beyer, H.

2007-06-01

67

Torsional actuation with extension-torsion composite coupling and a magnetostrictive actuator  

NASA Astrophysics Data System (ADS)

An analytical-experimental study of using magnetostrictive actuators in conjunction with an extension-torsion coupled composite tube to actuate a rotor blade trailing-edge flap to actively control helicopter vibration is presented. Thin walled beam analysis based on Vlasov theory was used to predict the induced twist and extension in a composite tube with magnetostrictive actuation. The study achieved good correlation between theory and experiment. The Kevlar-epoxy systems showed good correlation between measured and predicted twist values.

Bothwell, Christopher M.; Chandra, Ramesh; Chopra, Inderjit

1995-04-01

68

Induced Angular Momentum  

ERIC Educational Resources Information Center

Discusses, classically and quantum mechanically, the angular momentum induced in the bound motion of an electron by an external magnetic field. Calculates the current density and its magnetic moment, and then uses two methods to solve the first-order perturbation theory equation for the required eigenfunction. (Author/GA)

Parker, G. W.

1978-01-01

69

Dynamics of the I + HI --> IH + I reaction: application of nearside-farside, local angular momentum and resummation theories using the Fuller and Hatchell decompositions.  

PubMed

The differential cross section (DCS) for the I + HI(v(i) = 0, j(i) = 0) --> IH(v(f) = 0, j(f) = 2) + I reaction at a translational energy of 21.3 meV is studied, where v(i), j(i) and v(f), j(f) are vibrational, rotational quantum numbers for the initial and final states respectively. We apply new theoretical developments (since 2001) in nearside-farside (NF) theory to provide insights into intricate oscillatory structures in its DCS. It is shown that a simple physically-meaningful parameterization of the scattering (S) matrix, using a background Gaussian term plus a single Regge pole and a quadratic phase, can reproduce, in the forward and sideward directions, the intricate angular scattering obtained from numerical S matrix elements computed from a quantum Born-Oppenheimer-Centrifugal-Sudden scattering technique. This encouraging result suggests that many S matrix elements obtained from computer-intensive calculations can be parameterized in a similar physically-meaningful way. The manner in which the full and NF DCSs change when the Regge pole becomes progressively less important compared to the Gaussian term is also investigated. We report the first application to reactive scattering of the Hatchell NF decomposition, including resummations of the Legendre partial wave series for the scattering amplitude. The Hatchell NF resummed DCSs are compared with the corresponding Fuller NF resummed DCSs for resummation orders of r = 0, 1, 2 and 3. We find that the Fuller NF decomposition always provides a better physical interpretation of the angular scattering. Resummation usually cleans the NF DCSs of unphysical oscillations, especially in the farside (F) DCSs, with the greatest cleaning effect on going from no resummation (r = 0) to first order resummation (r = 1). Identities are derived which relate the Fuller and Hatchell NF subamplitudes for resummation orders, r > 0, to the NF unresummed subamplitudes, r = 0. These identities help us understand the origin of unexpected peaks, which sometimes appear in NF resummed DCSs, together with a simple procedure to remove them. We report Local Angular Momentum (LAM) and DCS x LAM (CLAM) analyses of the angular scattering for r = 0 and r = 1 using the Fuller NF decomposition. The LAM and CLAM analyses provide complementary (yet consistent) information to that obtained from the NF resummed DCSs. It is shown that the "l window representation", as used to analyse elastic scattering in the presence of strong absorption, is a special case of the general resummation theory developed in this paper. PMID:20498904

Totenhofer, A J; Noli, C; Connor, J N L

2010-08-21

70

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  

SciTech Connect

We show 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. 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.

Bradas, J.C.; Fennelly, A.J.; Smalley, L.L.

1987-04-15

71

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. Final report for the period ending September 1986  

SciTech Connect

We show 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 spin density of Ray and Smalley. This is made explicit by 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.

Bradas, J.C.

1987-06-01

72

[Spermatic cord torsion].  

PubMed

Torsion of the spermatic cord constitutes a surgical emergency. Morphologically and functionally, the fate of the compromised testis largely depends on the time elapsed between the acute episode and surgical intervention. Patients who had been treated for testicular torsion by our group from 1976 to 1989 were requested to return for outpatient evaluation. These patient were divided into two groups according to the time elapsed between the diagnosis and surgical intervention. We observed that surgical correction within 12 hours following presentation permitted testicular salvage. Testicular volume was generally preserved and remained normal or slightly diminished. However, when the time elapsed was over 12 hours, testicular atrophy was observed in 46% of the patients. We can conclude, therefore, that detorsion must be performed as soon as possible. Vaginalis testis eversion will generally achieve stable and lasting fixation. PMID:1586216

Malossini, G; Curti, P; Comunale, L; Bianchi, G; Baldassarre, R; Carluccio, G; Poletti, G

1992-01-01

73

Constraining spacetime torsion with the Moon and Mercury  

SciTech Connect

We report a search for new gravitational physics phenomena based on Riemann-Cartan theory of general relativity including spacetime torsion. Starting from the parametrized torsion framework of Mao, Tegmark, Guth, and Cabi, we analyze the motion of test bodies in the presence of torsion, and, in particular, we compute the corrections to the perihelion advance and to the orbital geodetic precession of a satellite. We consider the motion of a test body in a spherically symmetric field, and the motion of a satellite in the gravitational field of the Sun and the Earth. We describe the torsion field by means of three parameters, and we make use of the autoparallel trajectories, which in general differ from geodesics when torsion is present. We derive the specific approximate expression of the corresponding system of ordinary differential equations, which are then solved with methods of celestial mechanics. We calculate the secular variations of the longitudes of the node and of the pericenter of the satellite. The computed secular variations show how the corrections to the perihelion advance and to the orbital de Sitter effect depend on the torsion parameters. All computations are performed under the assumptions of weak field and slow motion. To test our predictions, we use the measurements of the Moon's geodetic precession from lunar laser ranging data, and the measurements of Mercury's perihelion advance from planetary radar ranging data. These measurements are then used to constrain suitable linear combinations of the torsion parameters.

March, Riccardo; Bellettini, Giovanni; Tauraso, Roberto; Dell'Agnello, Simone [Istituto per le Applicazioni del Calcolo, CNR, Via dei Taurini 19, 00185 Roma, Italy, and INFN - Laboratori Nazionali di Frascati (LNF), via E. Fermi 40 Frascati, 00044 Roma (Italy); Dipartimento di Matematica, Universita di Roma ''Tor Vergata'', via della Ricerca Scientifica 1, 00133 Roma, Italy, and INFN - Laboratori Nazionali di Frascati (LNF), via E. Fermi 40 Frascati, 00044 Roma (Italy); Dipartimento di Matematica, Universita di Roma 'Tor Vergata', via della Ricerca Scientifica 1, 00133 Roma, Italy, and INFN - Laboratori Nazionali di Frascati (LNF), via E. Fermi 40 Frascati, 00044 Roma (Italy); INFN - Laboratori Nazionali di Frascati (LNF), via E. Fermi 40 Frascati, 00044 Roma (Italy)

2011-05-15

74

Constraining spacetime torsion with the Moon and Mercury  

NASA Astrophysics Data System (ADS)

We report a search for new gravitational physics phenomena based on Riemann-Cartan theory of general relativity including spacetime torsion. Starting from the parametrized torsion framework of Mao, Tegmark, Guth, and Cabi, we analyze the motion of test bodies in the presence of torsion, and, in particular, we compute the corrections to the perihelion advance and to the orbital geodetic precession of a satellite. We consider the motion of a test body in a spherically symmetric field, and the motion of a satellite in the gravitational field of the Sun and the Earth. We describe the torsion field by means of three parameters, and we make use of the autoparallel trajectories, which in general differ from geodesics when torsion is present. We derive the specific approximate expression of the corresponding system of ordinary differential equations, which are then solved with methods of celestial mechanics. We calculate the secular variations of the longitudes of the node and of the pericenter of the satellite. The computed secular variations show how the corrections to the perihelion advance and to the orbital de Sitter effect depend on the torsion parameters. All computations are performed under the assumptions of weak field and slow motion. To test our predictions, we use the measurements of the Moon’s geodetic precession from lunar laser ranging data, and the measurements of Mercury’s perihelion advance from planetary radar ranging data. These measurements are then used to constrain suitable linear combinations of the torsion parameters.

March, Riccardo; Bellettini, Giovanni; Tauraso, Roberto; Dell'Agnello, Simone

2011-05-01

75

Laser-driven torsional coherences.  

PubMed

We discuss several interesting phenomena in the dynamics of strong field-triggered torsional wavepackets, which carry implications for the problem of torsional alignment in nonrigid molecules. Our results point to the origin and consequences of the fundamental differences between rotational and torsional coherences. In addition, we provide design guidelines for torsional control experiments by illustrating the role played by the laser intensity, pulse width, temperature, and molecular parameters. Specifically, as an example of several classes of molecules expected to make suitable candidates for laboratory experiments, we explore the torsional control of 9-[2-(anthracen-9-yl)ethynyl]anthracene and contrast it with that of biphenyl. Finally, we propose several potential applications for coherent torsional control in chemistry, physics, and material science. PMID:23387587

Ashwell, Benjamin A; Ramakrishna, S; Seideman, Tamar

2013-01-28

76

Performance of an angular flange aeroelastic wind energy converter  

SciTech Connect

ALL conventional wind turbines operate on the principles of turbomachinaries, with wind being made to flow over a set of rotating vanes. Recently, a new concept for wind energy conversion based on aeroelastic instability was introduced. It is well known that couplings between the vibration of an elastic structure and fluid stream may lead to aeroelastic instability. Energy then is transferred from the airstream into the elastic structure, which results in a destructive monotonic increase of the vibration amplitude of the structure. The failure of the Tacoma Narrows Bridge is one of the well-known examples of such a disaster. The use of an aeroelastic instability (or flutter) mechanism for constructing a wind energy converter was suggested. The theory for a torsional wind energy converter and the results of some model tests were also presented. Recently, some studies on similar types of wind energy converters using oscillating airfoils were reported. In the present study an angular flange H-section model of a torsional aeroelastic wind energy converter is constructed, and its performances under various conditions are investigated. The effects of the variations of the flange angle and the flange width on the performance of the model are studied. The weight of the pendulum is also varied, and its effects on the power coefficient of the model are investigated. It is observed that the efficiency of energy conversion decreases with an increase in wind speed. A method for possible improvement of the theoretical prediction is suggested and discussed.

Ahmadi, G.

1983-05-01

77

Torsional flutter of bluff bodies  

Microsoft Academic Search

This paper describes the torsional flutter mechanism of 2D rectangular cylinders and 2D H-shaped cylinders based upon unsteady pressure measurements under forced torsional vibration. For some cylinders with certain side ratio (BD, B: chord length, D: cylinder thickness), such as BD = 5 to BD = 12.5, in the high reduced velocity range, that is V\\/f B> 10 (f: torsional

Masaru Matsumoto; Yoshiyuki Daito; Fumitaka Yoshizumi; Yasuo Ichikawa; Tadahiro Yabutani

1997-01-01

78

Gallbladder Torsion: A Diagnostic Challenge  

PubMed Central

80-year-old female presented with clinical findings suggestive of acute cholecystitis. Intraoperatively we discovered a dusky gallbladder with gangrenous patches and gallbladder torsion with 270 degrees clockwise rotation along the longitudinal axis. Gallbladder torsion is a rare cause of acute cholecystitis with less than 500 cases published in the literature. Gallbladder torsion should be included in the list of differential diagnoses in patients suspected of having acute cholecystitis especially when there are inconsistencies between clinical features and imaging. It is worth noting that 3-dimensional reconstructed CT may be useful in preoperative diagnosis of gallbladder torsion.

Bradshaw, Kimberley; Jeyarajan, Eshwarshanker; Alzubaidy, Rafid; Liew, Victor

2014-01-01

79

Randall-Sundrum scenario with bulk dilaton and torsion  

SciTech Connect

We consider a string-inspired torsion-dilaton-gravity action in a Randall-Sundrum braneworld scenario and show that, in an effective four-dimensional theory on the visible brane, the rank-2 antisymmetric Kalb-Ramond field (source of torsion) is exponentially suppressed. The result is similar to our earlier result in [B. Mukhopadhyaya, S. Sen, and S. SenGupta, Phys. Rev. Lett. 89, 121101 (2002); Phys. Rev. Lett. 89, 259902(E) (2002)], where no dilaton was present in the bulk. This offers an explanation of the apparent invisibility of torsion in our space-time. However, in this case the trilinear couplings {approx}TeV{sup -1} between the dilaton and torsion may lead to new signals in TeV-scale experiments, bearing the stamp of extra warped dimensions.

Mukhopadhyaya, Biswarup; Sen, Somasri; SenGupta, Soumitra [Regional Centre for Accelerator-based Particle Physics, Harish-Chandra Research Institute, Chhatnag Road, Jhusi, Allahabad - 211 019 (India); Centre for Theoretical Physics, Jamia Millia Islamia, New Delhi 110 025 (India); Department of Theoretical Physics, Indian Association for the Cultivation of Science, Kolkata - 700 032 (India)

2009-06-15

80

Torsional surface waves in a gradient-elastic half-space  

Microsoft Academic Search

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

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

2000-01-01

81

Angular Momentum  

ERIC Educational Resources Information Center

The gyroscope in a smartphone was employed in a physics laboratory setting to verify the conservation of angular momentum and the nonconservation of rotational kinetic energy. As is well-known, smartphones are ubiquitous on college campuses. These devices have a panoply of built-in sensors. This creates a unique opportunity for a new paradigm in…

Shakur, Asif; Sinatra, Taylor

2013-01-01

82

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

NASA Technical Reports Server (NTRS)

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.

Herakovich, C. T.

1978-01-01

83

Torsional Electromechanics of Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

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.

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

2007-03-01

84

Big bounce from spin and torsion  

NASA Astrophysics Data System (ADS)

The Einstein-Cartan-Sciama-Kibble theory of gravity naturally extends general relativity to account for the intrinsic spin of matter. Spacetime torsion, generated by spin of Dirac fields, induces gravitational repulsion in fermionic matter at extremely high densities and prevents the formation of singularities. Accordingly, the big bang is replaced by a bounce that occurred when the energy density {? ? gT^4} was on the order of {n^2/m_Pl^2} (in natural units), where {n ? gT^3} is the fermion number density and g is the number of thermal degrees of freedom. If the early Universe contained only the known standard-model particles ( g ? 100), then the energy density at the big bounce was about 15 times larger than the Planck energy. The minimum scale factor of the Universe (at the bounce) was about 1032 times smaller than its present value, giving ? 50 ?m. If more fermions existed in the early Universe, then the spin-torsion coupling causes a bounce at a lower energy and larger scale factor. Recent observations of high-energy photons from gamma-ray bursts indicate that spacetime may behave classically even at scales below the Planck length, supporting the classical spin-torsion mechanism of the big bounce. Such a classical bounce prevents the matter in the contracting Universe from reaching the conditions at which a quantum bounce could possibly occur.

Pop?awski, Nikodem J.

2012-04-01

85

Torsion tests of tubes  

NASA Technical Reports Server (NTRS)

This report presents the results of tests of 63 chromium-molybdenum steel tubes and 102 17st aluminum-alloy tubes of various sizes and lengths made to study the dependence of the torsional strength on both the dimensions of the tube and the physical properties of the tube material. Three types of failure are found to be important for sizes of tubes frequently used in aircraft construction: (1) failure by plastic shear, in which the tube material reached its yield strength before the critical torque was reached; (2) failure by elastic two-lobe buckling, which depended only on the elastic properties of the tube material and the dimensions of the tube; and (3) failure by a combination of (1) and (2) that is, by buckling taking place after some yielding of the tube material.

Stang, Ambrose H; Ramberg, Walter; Back, Goldie

1937-01-01

86

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.

87

Angular momentum  

NASA Astrophysics Data System (ADS)

The gyroscope in a smartphone was employed in a physics laboratory setting to verify the conservation of angular momentum and the nonconservation of rotational kinetic energy. As is well-known, smartphones are ubiquitous on college campuses. These devices have a panoply of built-in sensors. This creates a unique opportunity for a new paradigm in the physics laboratory.1-3 Many traditional physics experiments can now be performed very conveniently in a pedagogically enlightening environment while simultaneously reducing the laboratory budget substantially by using student-owned smartphones.

Shakur, Asif; Sinatra, Taylor

2013-12-01

88

The torsional strength of wings  

NASA Technical Reports Server (NTRS)

This report describes a simple method for calculating the position of the elastic axis of a wing structure having any number of spars. It is shown that strong drag bracing near the top and bottom of a wing greatly increases the torsional strength. An analytical procedure for finding the contribution of the drag bracing to the torsional strength and stiffness is described, based upon the principle of least work, and involving only one unknown quantity. A coefficient for comparing the torsional rigidity of different wings is derived in this report.

Burgess, C P

1930-01-01

89

[Seminoma necrosis by testicular torsion].  

PubMed

The coincidence of a classical scrotal testicular torsion with a scrotal tumor is a rare event. In the case described here the classical histological characteristics of a seminoma were present in addition to clear signs of testicular torsion with fibrin-containing thrombi in the intratesticular capillaries, so that the ischemia time predicted by the pathologists correlated well with the clinical data of 7.5 h for the testicular torsion estimated at the time of the intervention. The intraoperative diagnosis made by the surgeon allowed a rapid response with only a semi-castration, excision of the wound edges and a highest possible amputation of the funiculus. PMID:19859689

Wiedemann, A; Zienkiewicz, T

2010-01-01

90

Contribution to the theory of propeller vibrations  

NASA Technical Reports Server (NTRS)

This report presents a calculation of the torsional frequencies of revolving bars with allowance for the air forces. Calculation of the flexural or bonding frequencies of revolving straight or tapered bars in terms of the angular velocity of revolution. Calculation on the basis of Rayleigh's principle of variation. There is also a discussion of error estimation and the accuracy of results. The author then provides an application of the theory to screw propellers for airplanes and the discusses the liability of propellers to damage through vibrations due to lack of uniform loading.

Liebers, F

1930-01-01

91

Single-molecule torsional pendulum.  

PubMed

We have built a torsional pendulum based on an individual single-walled carbon nanotube, which is used as a torsional spring and mechanical support for the moving part. The moving part can be rotated by an electric field, resulting in large but fully elastic torsional deformations of the nanotube. As a result of the extremely small restoring force associated with the torsional deformation of a single molecule, unusually large oscillations are excited by the thermal energy of the pendulum. By diffraction analysis, we are able to determine the handedness of the molecule in our device. Mechanical devices with molecular-scale components are potential building blocks for nanoelectromechanical systems and may also serve as sensors or actuators. PMID:16141068

Meyer, Jannik C; Paillet, Matthieu; Roth, Siegmar

2005-09-01

92

Constraining spacetime torsion with LAGEOS  

NASA Astrophysics Data System (ADS)

We compute the corrections to the orbital Lense-Thirring effect (or frame-dragging) in the presence of spacetime torsion. We analyze the motion of a test body in the gravitational field of a rotating axisymmetric massive body, using the parametrized framework of Mao, Tegmark, Guth and Cabi. In the cases of autoparallel and extremal trajectories, we derive the specific approximate expression of the corresponding system of ordinary differential equations, which are then solved with methods of Celestial Mechanics. We calculate the secular variations of the longitudes of the node and of the pericenter. We also show how the LAser GEOdynamics Satellites (LAGEOS) can be used to constrain torsion parameters. We report the experimental constraints obtained using both the nodes and perigee measurements of the orbital Lense-Thirring effect. This makes LAGEOS and Gravity Probe B complementary frame-dragging and torsion experiments, since they constrain three different combinations of torsion parameters.

March, Riccardo; Bellettini, Giovanni; Tauraso, Roberto; Dell'Agnello, Simone

2011-11-01

93

Fermi Liquid in a Torsional Oscillator  

NASA Astrophysics Data System (ADS)

We study the transverse acoustic impedance of normal Fermi liquid inside a torsionally oscillating cylindrical container. We use Landau's Fermi liquid theory, and our approach is applicable to both normal 3He and mixtures of 3He in superfluid 4He. The fluid causes dissipation and a change of the resonant frequency of the oscillator. Usually, a liquid medium increases the moment of inertia of the oscillator, but we show that for a suitable choice of container radius and driving frequency, the Fermi liquid can actually decrease the inertia and increase the resonant frequency. Results of numerical calculations for all values of mean free path l are shown and comparison is made to both hydrodynamic theory and simple kinetic theory in the ballistic limit.

Virtanen, T. H.; Thuneberg, E. V.

2012-12-01

94

Deligne-Beilinson cohomology and Abelian link invariants: Torsion case  

SciTech Connect

For the Abelian Chern-Simons field theory, we consider the quantum functional integration over the Deligne-Beilinson cohomology classes and present an explicit path-integral nonperturbative computation of the Chern-Simons link invariants in SO(3){approx_equal}RP{sup 3}, a toy example of a 3-manifold with torsion.

Thuillier, F. [LAPTH, Universite de Savoie, Chemin de Bellevue, BP 110, F-74941 Annecy-le-Vieux Cedex (France)

2009-12-15

95

Torsional vibration of aircraft engines  

NASA Technical Reports Server (NTRS)

Exhaustive torsional-vibration investigations are required to determine the reliability of aircraft engines. A general outline of the methods used for such investigations and of the theoretical and mechanical means now available for this purpose is given, illustrated by example. True vibration diagrams are usually obtained from vibration measurements on the completed engine. Two devices for this purpose and supplementing each other, the D.V.L. torsiograph and the D.V.L. torsion recorder, are described in this report.

Lurenbaum, Karl

1932-01-01

96

Torsion Stiffness of a Protein Pair Determined by Magnetic Particles  

PubMed Central

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.

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

97

Quick phases control ocular torsion during smooth pursuit.  

PubMed

One of the open questions in oculomotor control of visually guided eye movements is whether it is possible to smoothly track a target along a curvilinear path across the visual field without changing the torsional stance of the eye. We show in an experimental study of three-dimensional eye movements in subhuman primates (Macaca mulatta) that although the pursuit system is able to smoothly change the orbital orientation of the eye's rotation axis, the smooth ocular motion was interrupted every few hundred milliseconds by a small quick phase with amplitude <1.5° while the animal tracked a target along a circle or ellipse. Specifically, during circular pursuit of targets moving at different angular eccentricities (5°, 10°, and 15°) relative to straight ahead at spatial frequencies of 0.067 and 0.1 Hz, the torsional amplitude of the intervening quick phases was typically around 1° or smaller and changed direction for clockwise vs. counterclockwise tracking. Reverse computations of the eye rotation based on the recorded angular eye velocity showed that the quick phases facilitate the overall control of ocular orientation in the roll plane, thereby minimizing torsional disturbances of the visual field. On the basis of a detailed kinematic analysis, we suggest that quick phases during curvilinear smooth tracking serve to minimize deviations from Donders' law, which are inevitable due to the spherical configuration space of smooth eye movements. PMID:21715669

Hess, Bernhard J M; Thomassen, Jakob S

2011-11-01

98

Experimental bounds on the coupling of massless spin-1 torsion  

Microsoft Academic Search

Agreement of reactor neutrino data with Weinberg-Salam neutral current theory is shown to imply (g\\/sub T\\/\\/sup ts2\\/\\/4..pi..)<10⁻¹°, where g\\/sub T\\/ is the coupling of a massless spin-1 torsion multiplet to fermions. If one demands that emission of massless spin-1 torsion quanta not destroy the energy balance inside helium-burning stars, one obtains a stronger limit (g\\/sub T\\/\\/sup ts2\\/\\/4..pi..)<10⁻³⁴. This bound is

Donald Neville

1982-01-01

99

Controlling electron transfer through the manipulation of structure and ligand-based torsional motions: a computational exploration of ruthenium donor-acceptor systems using density functional theory.  

PubMed

Computational studies using density functional theory (DFT) are reported for a series of donor-acceptor (DA) transition metal complexes and related excited-state and electron transfer (ET) photoproduct models. Three hybrid Hartree-Fock/DFT (HF/DFT) functionals, B3LYP, B3PW91, and PBE1PBE, are employed to characterize structural features implicated in the dynamical control of productive forward and energy wasting back ET events. Energies and optimized geometries are reported for the lowest energy singlet state in [Ru(dmb)(2)(bpy-phi-MV)](4+) (DA1), [Ru(dmb)(2)(bpy-o-tolyl-MV)](4+) (DA2), [Ru(dmb)(2)(bpy-2,6-Me(2)-phi-MV)](4+) (DA3), and [Ru(tmb)(2)(bpy-2,6-Me(2)-phi-MV)](4+) (DA3'), where dmb is 4,4'-dimethyl-2,2'-bipyridine, tmb is 4,4',5,5'-tetramethyl-2,2'-bipyridine, MV is methyl viologen, and phi is a phenylene spacer. These indicate that the dihedral angle theta(1) between the aryl substituent and the bipyridine fragment to which it is bound, systematically increases with the addition of steric bulk. Energies, optimized geometries, and unpaired electron spin densities are also reported for the lowest energy triplet state of [Ru(dmb)(2)(4-p-tolyl-2,2'-bipyridine)](2+) (D1*), [Ru(dmb)(2)(4-(2,6-dimethylphenyl)-2,2'-bipyridine)](2+) (D2*), [Ru(dmb)(2)(4-mesityl-2,2'-bipyridine)](2+) (D3*), and [Ru(tmb)(2)(4-mesityl-2,2'-bipyridine)](2+) (D3'*). Each of these serves as a model of a reactant excited state in the forward electron-transfer photochemistry allowing us to qualify and quantify the role of excited-state intraligand electron delocalization in driving substantial geometry changes (especially with respect to theta(1)) relative to its respective DA counterpart. Next, energies, optimized geometries, and spin densities are reported for the lowest energy triplet of each DA species: (3)DA1, (3)DA2, (3)DA3, and (3)DA3'. These are used to model the ET photoproduct and they indicate that theta(1) increases following ET, thus, verifying switch-like properties. Finally, we report data for geometry optimized DA1 and (3)DA1 in a continuum model of room temperature acetonitrile. This study shows a complete recovery of theta(1) to its ground state value which has implications in efforts to trap electrons in charge-separated states. PMID:19856899

Meylemans, Heather A; Damrauer, Niels H

2009-12-01

100

Experimental bounds on the coupling of massless spin-1 torsion  

SciTech Connect

Agreement of reactor neutrino data with Weinberg-Salam neutral current theory is shown to imply (g/sub T//sup ts2//4..pi..)<10/sup -10/, where g/sub T/ is the coupling of a massless spin-1 torsion multiplet to fermions. If one demands that emission of massless spin-1 torsion quanta not destroy the energy balance inside helium-burning stars, one obtains a stronger limit (g/sub T//sup ts2//4..pi..)<10/sup -34/. This bound is extremely strict, yet a torsion-balance experiment recently suggested by Newman should be able to improve even this bound by several orders of magnitude.

Neville, D.E.

1982-01-15

101

Simple torsion test for shear moduli determination of orthotropic composites  

NASA Technical Reports Server (NTRS)

By means of torsion tests performed on test specimens of the same material having a minimum of two different cross sections (flat sheet of different widths), the effective in-plane (G13) and out-of-plane (G23) shear moduli were determined for two composite materials of uniaxial and angleply fiber orientations. Test specimens were 16 plies (nominal 2 mm) thick, 100 mm in length, and in widths of 6.3, 9.5, 12.5, and 15.8 mm. Torsion tests were run under controlled deflection (constant angle of twist) using an electrohydraulic servocontrolled test system. In-plane and out-of-plane shear moduli were calculated from an equation derived in the theory of elasticity which relates applied torque, the torsional angle of twist, the specimen width/thickness ratio, and the ratio of the two shear moduli G13/G23. Results demonstrate that torsional shear moduli, G23 as well as G13, can be determined by simple torsion tests of flat specimens of rectangular cross section. Neither the uniaxial nor angleply composite material were transversely isotropic.

Sumsion, H. T.; Rajapakse, Y. D. S.

1978-01-01

102

Properties of Threaded Rod Torsion Pendulums  

NASA Astrophysics Data System (ADS)

Threaded rod torsion pendulums provide an inexpensive and reasonably low-mass approach to the study of torsion pendulums in AP Physics. Characteristics such as the relationship between the torsion constant and the length and diameter of the torsion rod can be easily determined with the use of threaded rods. They can also be used for the study of damping and driven effects in torsion systems. Since the rotational inertia of a torsion pendulum is central to its behavior, the use of threaded rod systems increases the facility with which this concept can be studied.

Atalis, Alexandra; Omar, Javid

2009-04-01

103

Tibiofibular torsion in congenital clubfoot.  

PubMed

Tibiofibular torsion was measured by computed tomography in three series of patients affected by congenital clubfoot who were treated with different protocols. The normal leg of unilateral deformities served as the control. For the bilateral cases, only the right side was included in the study. The angle between the bicondylar axis of the tibia and the bimalleolar axis was the index of tibiofibular torsion. There were 34 clubfeet in the first series, treated with a posteromedial release, and 40 clubfeet in the second series, treated with a modified Ponseti method, whereas the third series included 16 clubfeet, treated with the original Ponseti method. All 90 clubfeet were graded at birth as group 3 according to the Manes classification. No patient had previous treatment. The patients of the first and the second series were followed up to maturity, whereas the patients of the third series were followed up to a maximum of 11 years of age. In the congenital clubfoot, the tibia and the fibula were externally rotated, in comparison with the normal leg; in fact, the average value of the angle of tibiofibular torsion was 32.2° in the first series, 23.9° in the second series, and 21.1° in the third series. In the normal tibiae, the average value of the angle of tibiofibular torsion was 21.4°. The difference between the first series and the normal controls was statistically significant, as was the difference between the first one and the other two series. The value of the tibiofibular torsion angle seems to be related to the manipulation technique used to treat clubfoot: when the manipulation does not allow a progressive eversion of the talus underneath the calcaneus, the external tibial torsion increases. At follow-up, an intoeing gait was present in seven treated clubfeet of the first series. In all of them except one, the highest value of the external tibial torsion angle was observed, with a low value of the Kite's angle and/or residual forefoot adduction. In the treated congenital clubfoot, persistent intoeing is not related to the angle of tibial torsion but rather to the amount of correction of calcaneal inversion and residual forefoot adduction. PMID:22027706

Farsetti, Pasquale; Dragoni, Massimiliano; Ippolito, Ernesto

2012-01-01

104

Angular quasi-phase-matching  

SciTech Connect

We propose a generalization of quasi-phase-matching of quadratic nonlinear processes that we call angular quasi-phase-matching (AQPM). It corresponds to a propagation of three collinear interacting electromagnetic waves in a periodically poled nonlinear medium at any angle with respect to the grating vector. AQPM directions are analyzed using groups theory.

Petit, Yannick; Boulanger, Benoit; Segonds, Patricia [Institut Neel / CNRS-UJF, Boite Postale 166, F 38042 Grenoble Cedex 9 (France); Taira, Takunori [Institute for Molecular Science, 38 Nishigonaka, Myodaiji, Okazaki, 444-8585 (Japan)

2007-12-15

105

Optical activity caused by torsion stresses: the case of NaBi(MoO4)2 crystals.  

PubMed

We have found that torsion mechanical stresses induce the optical rotation effect in centrosymmetric NaBi(MoO4)2 crystals. We have suggested a description of the effect on the basis of nonlocal linear elasticity theory. It has been shown that the induced optical gyration is proportional to the stress gradient appearing due to the torsion. PMID:23695320

Vasylkiv, Yuriy; Kvasnyuk, Oleksiy; Shopa, Yaroslav; Vlokh, Rostyslav

2013-05-01

106

Non-linear torsional vibration characteristics of an internal combustion engine crankshaft assembly  

NASA Astrophysics Data System (ADS)

Crankshaft assembly failure is one of the main factors that affects the reliability and service life of engines. The linear lumped mass method, which has been universally applied to the dynamic modeling of engine crankshaft assembly, reveals obvious simulation errors. The nonlinear dynamic characteristics of a crankshaft assembly are instructionally significant to the improvement of modeling correctness. In this paper, a general expression for the non-constant inertia of a crankshaft assembly is derived based on the instantaneous kinetic energy equivalence method. The nonlinear dynamic equations of a multi-cylinder crankshaft assembly are established using the Lagrange rule considering nonlinear factors such as the non-constant inertia of reciprocating components and the structural damping of shaft segments. The natural frequency and mode shapes of a crankshaft assembly are investigated employing the eigenvector method. The forced vibration response of a diesel engine crankshaft assembly taking into account the non-constant inertia is studied using the numerical integral method. The simulation results are compared with a lumped mass model and a detailed model using the system matrix method. Results of non-linear torsional vibration analysis indicate that the additional excitation torque created by non-constant inertia activates the 2nd order rolling vibration, and the additional damping torque resulting from the non-constant inertia is the main nonlinear factor. The increased torsional angular displacement evoked by the high order excitation torque relates to the non-constant inertia. This research project is aimed at improving nonlinear dynamics theory, and the confirmed nonlinear parameters can be used for the structure design of a crankshaft assembly.

Huang, Ying; Yang, Shouping; Zhang, Fujun; Zhao, Changlu; Ling, Qiang; Wang, Haiyan

2012-07-01

107

A torsional vibration measurement system  

Microsoft Academic Search

At the development stage of automobile construction, many power-train configurations may be considered. Due to complicated coupling mechanisms, the natural frequencies of the combined system are difficult to predict. It is therefore necessary to run tests on automotive subsystems under realistic operating conditions. To fully understand the dynamic behavior, a study of both torsional and translational motions along the driveshaft

Peishuh Wang; Patricia Davies; John M. Starkey; Richard L. Routson

1992-01-01

108

Torsion and supersymmetry breaking  

Microsoft Academic Search

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) × SU(3)

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

2008-01-01

109

Les torsions sur testicules cryptorchides  

PubMed Central

Résumé But : La cryptorchidie est une pathologie assez fréquente en urologie. Elle est associée à un risque élevé d’infertilité et de dégénérescence. Elle semble aussi être associée à un risque important de torsion. Cette entité est très peu abordée dans la littérature. Nous rapportons tous les cas de torsion sur testicule cryptorchide observés à notre service dans le but de mieux caractériser cette pathologie et de réduire ainsi le taux d’orchidectomies. Méthodologie : Il s’agit d’une étude rétrospective portant sur tous les cas de torsion sur testicule cryptorchide opérés dans notre service d’urologie entre 1999 et 2007. Les patients ont fait l’objet d’une description basée sur le résumé de leurs observations. Résultats : Les patients étaient âgés de 7 mois à 39 ans. La torsion touchait le testicule droit dans 53 % des cas. Le tableau clinique comportait une douleur au niveau de la région inguinale d’apparition soudaine avec une masse sous-cutanée inflammatoire et douloureuse à ce niveau et surtout un hémiscrotum homolatéral vide. Dans 60 % des cas, le diagnostic était tardif et une orchidectomie a été réalisée. Dans les autre cas, un abaissement du testicule a été réalisé avec orchidopexie controlatéral dans le même temps opératoire. Conclusion : Bien qu’il s’agisse d’une pathologie peu courante, la torsion sur testicule cryptorchide doit être étudiée davantage. Le diagnostic précoce permettra de sauver et d’abaisser le testicule et faciliter ainsi le dépistage d’une éventuelle dégénérescence.

Gharbi, Mohamed; Amri, Najmeddine; Chambeh, Wahib; Braiek, Salem; Kamel, Rafik El

2010-01-01

110

Angular momentum in subbarrier fusion  

SciTech Connect

We have measured the ratio of the isomer to ground-state yields of {sup 137}Ce produced in the fusion reactions {sup 128}Te({sup 12}C,3n), {sup 133}Cs({sup 7}Li,3n), {sup 136}Ba({sup 3}He,2n), {sup 136}Ba({sup 4}He,3n), and {sup 137}Ba({sup 3}He,3n), from energies above the Coulomb barrier to energies typically 20--30% below the barrier by observing the delayed x- and {gamma}-ray emission. We deduce the average angular momentum, {lt}J{gt}, from the measured isomer ratios with a statistical model. In the first three reactions we observe that the values of {lt}J{gt} exhibit the behavior predicted for low energies and the expected variation with the reduced mass of the entrance channel. We analyze these data and the associated cross sections with a barrier penetration model that includes the coupling of inelastic channels. Measurements of average angular momenta and cross sections made on other systems using the {gamma}-multiplicity and fission-fragment angular correlation techniques are then analyzed in a similar way with this model. The discrepancies with theory for the {gamma}-multiplicity data show correlations in cross section and angular momentum that suggest a valid model can be found. The measurements of angular momentum using the fission fragment angular correlation technique, however, do not appear reconcilable with the energy dependence of the cross sections. This systematic overview suggests, in particular, that our current understanding of the relationship of angular momentum and anisotropy in fission fragment angular correlations is incomplete. 26 refs.

DiGregorio, D.E.; Lesko, K.T.; Harmon, B.A.; Norman, E.B.; Pouliot, J.; Sur, B.; Chan, Y.D.; Stokstad, R.G.

1990-05-01

111

Combined bending-torsion fatigue reliability. III  

NASA Technical Reports Server (NTRS)

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.

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

1975-01-01

112

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)

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.

Ueki, Taro; Larsen, Edward W.

1998-09-01

113

Forward models of torsional waves: dispersion and geometric effects  

NASA Astrophysics Data System (ADS)

Alfvén waves are a set of transverse waves that propagate in an electrically conducting fluid in the presence of an ambient magnetic field. Studies of such waves in the Earth's interior are important because they can be used to make inferences about the structure and physical properties of the core that would otherwise remain inaccessible. We produce 1-D forward models of cylindrical torsional Alfvén waves in the Earth's core, also known as torsional oscillations, and study their evolution in a full sphere and an equatorially symmetric spherical shell. Here, we find that travelling torsional waves undergo significant geometric dispersion that increases with successive reflections from the boundaries such that an initial wave pulse becomes unidentifiable within three transits of the core. Low amplitude wakes trail behind sharply defined pulses during propagation, a phenomenon that we interpret using the failure of Huygens' principle in even dimensions. We investigate the relationship between geometric dispersion and wavelength, concluding that long-wavelength features are more dispersive than short-wavelength features. This result is particularly important because torsional waves that have been inferred in the Earth's core from secular variation are relatively long wavelength, and are therefore likely to undergo significant dispersion within the core. When stress-free boundary conditions on angular velocity are applied, waves are reflected at the equator of the core-mantle boundary with the same sign as the incident wave. Waves that pass through the rotation axis undergo a pseudo-reflection and display a more complicated behaviour due to a phase shift. In an equatorially symmetric shell, we identify a weak reflection at the tangent cylinder due to geometric effects.

Cox, G. A.; Livermore, P. W.; Mound, J. E.

2014-03-01

114

Modeling slender viscoelastic jets and fibers with torsion  

SciTech Connect

All thin-filament models to date are torsionless and consider only leading-order approximations in a slender asymptotic sense. This dissertation first presents a higher-order perturbation theory for slender viscoelastic jets and fibers, which allows full consideration of axisymmetric torsion. It then illustrates the practical applications of this higher-order perturbation theory through four practical examples. The steady equations through three orders for all four examples are solved to illustrate several points: (1) it is necessary to go to the higher-order corrections in order to check the leading-order approximation or to consider the torsional coupling; (2) many leading-order steady solutions are asymptotically valid and robust to neglected higher-order physical effects (the higher-order corrections are computed and found being small); (3) other leading-order solutions are invalid in the presence of higher-order effects; specifically, it is shown that corrections due to weak elastic relaxation can be as large as the Newtonian leading-order approximation; (4) it is straightforward using this higher-order perturbation theory to determine if a particular leading-order solution is a valid approximation of physical behavior; (5) torsion can have effect on both the mathematical structure of the model and higher-order corrections of the leading-order approximations.

Cao, J.

1992-01-01

115

Polymer dynamics in torsion space.  

PubMed

The large scale motion of proteins, or covalently bonded polymers in general, is governed by the dynamics of the torsion angles, with bond lengths and bond angles kept approximately constant. In the present work, the Lagrangian equations of torsion motion are derived for a general macromolecule. The dynamics is implemented numerically for a test protein, using the velocity Verlet method as the integrator. The results indicate time steps of up to about 30 fs can be used for short time (up to at least 20 ps) simulations, before the dynamics and energy start to differ significantly from results obtained with smaller time steps. For longer time simulations, up to 1000 ps, a time step of 10 fs is relatively safe. PMID:20058226

Henriksson, Krister O E; Pesonen, Janne

2010-07-15

116

Determination of diesel engine cylinder gas torques from speed fluctuations with a high-fidelity crankshaft torsional model  

Microsoft Academic Search

An experimental investigation was conducted to develop a method of predicting cylinder indicated torques in a reciprocating engine by measurement of crankshaft angular velocity fluctuations. Cylinder indicated pressures were measured for all three cylinders of a two-stroke Diesel engine with pressure transducers. Time-resolved angular position was measured at the crankshaft front and at the flywheel. A six degree-of-freedom torsional crankshaft

1998-01-01

117

Angular Momentum Experiment  

NSDL National Science Digital Library

After using the historical development of concepts of conserved motion to develop introductory understanding, students are directed to a series of activities to gain a better understanding of momentum, conservation of momenta, angular momentum, and conservation of angular momenta.

Trapp, David

118

Extension, torsion and expansion of an incompressible, hemitropic Cosserat circular cylinder  

Microsoft Academic Search

Constitutive equations for the stress and couple stres on an incompressible, hemitropic, constrained Cosserat material are derived, and the theory is applied to study the problem of finite extension, torsion and expansion of a circular cylinder. As in the theory of isotropic simple elastic materials, it is found that the deformation is controllable by application of only a normal force

K. J. Cheverton; M. F. Beatty

1981-01-01

119

Finite deformation analysis of mechanism-based strain gradient plasticity: torsion and crack tip field  

Microsoft Academic Search

A finite deformation theory of mechanism-based strain gradient (MSG) plasticity is developed in this paper based on the Taylor dislocation model. The theory ensures the proper decomposition of deformation in order to exclude the volumetric deformation from the strain gradient tensor since the latter represents the density of geometrically necessary dislocations. The solution for a thin cylinder under large torsion

K. C. Hwang; H. Jiang; Y. Huang; H. Gao

2003-01-01

120

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

NASA Technical Reports Server (NTRS)

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.

Angelaki, Dora E.; Dickman, J. David

2003-01-01

121

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

NASA Astrophysics Data System (ADS)

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(3P) + 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.

Czakó, Gábor

2014-06-01

122

Bending stresses due to torsion in cantilever box beams  

NASA Technical Reports Server (NTRS)

The paper beings with a brief discussion on the origin of the bending stresses in cantilever box beams under torsion. A critical survey of existing theory is followed by a summary of design formulas; this summary is based on the most complete solution published but omits all refinements considered unnecessary at the present state of development. Strain-gage tests made by NACA to obtained some experimental verification of the formulas are described next. Finally, the formulas are applied to a series of box beams previously static-tested by the U.S. Army Air Corps; the results show that the bending stresses due to torsion are responsible to a large extent for the free-edge type of failure frequently experienced in these tests.

Kuhn, Paul

1935-01-01

123

Physical dimensions, torsional performance, and metallurgical properties of rotary endodontic instruments. 3. Peeso drills.  

PubMed

A laboratory study was performed on Peeso drills to determine their physical dimensions, torsional performance, and metallurgical properties. Samples were measured from each of sizes #1 to #6 of Peeso drills (type P) and sizes #009 to #023 of Peeso drills (type B-1) from the two manufacturers that distribute these instruments in the United States. They were also tested in clockwise and counterclockwise torsion using a digital torque meter instrument. It was not possible to evaluate completely some type P drills of size #4 and larger or type B-1 drills of size #016 and larger because the torsional moments exceeded the capacity of the test instrument. Scanning electron microscopic examination confirmed visual observations that the stainless steel Peeso drills exhibited ductile torsional fracture, in contrast to the carbon steel Peeso drills which fractured in a relatively brittle manner. The carbon steel Peeso drills exhibited a much greater tendency for torsional fractures in the bur head, along with considerably smaller values of angular deflection at separation compared to the stainless steel Peeso drills. This study is part of a continuing investigation to establish standards for all rotary endodontic instruments. PMID:1402558

Luebke, N H; Brantley, W A; Sabri, Z I; Luebke, J H

1992-01-01

124

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

NASA Astrophysics Data System (ADS)

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.

Bhattacharjee, Srijit; Chatterjee, Ayan

2011-05-01

125

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

SciTech Connect

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.

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

126

Centrifuge Modeling of Torsionally Loaded Pile Groups  

Microsoft Academic Search

This paper reports a series of centrifuge model tests on torsionally loaded 1 2, 2 2, and 3 3 pile groups in sand. The objectives of the paper are to investigate: 1 the response of the pile groups subjected to torsion; 2 the way in which the applied torque is transferred in the pile groups; 3 the internal forces mobilized

L. G. Kong; L. M. Zhang

2007-01-01

127

Torsion of Noncircular Composite Cylinders  

NASA Technical Reports Server (NTRS)

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.

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

2005-01-01

128

Stellar accretion of matter possessing angular momentum  

SciTech Connect

Observations of novae and theoretical results, in which the authors studied the nova outburst by radially accreting H-rich matter onto an He white dwarf, have convinced them that realistic nova models must be based on accretion that includes the angular momentum of the accreting matter. In the present paper the authors develop the theory of accretion onto stars of matter possessing angular momentum, including the shear forces between the accreting matter and the star (assumed to be nonrotating), distribution of accreted matter and its angular momentum by turbulent mixing, thermalizing of rotational kinetic energy, and loss of energy by horizontal expansion. 25 references.

Kutter, G.S.; Sparks, W.M.

1987-10-01

129

Inevitable inflation in Einstein-Cartan theory with improved energy-momentum tensor with spin  

NASA Technical Reports Server (NTRS)

Generalized, or power-law, inflation is shown to necessarily exist for a simple, anisotropic, (Bianchi Type-1) cosmology in the Einstein-Cartan gravitational theory with the Ray-Smalley improved energy momentum tensor with spin. Formal solution of the EC field equations with the fluid equations of motion explicitly shows inflation caused by the RS spin angular kinetic energy density. Shear is not effective in preventing inflation in the ECRS model. The relation between fluid vorticity, torsion, reference axis rotation, and shear ellipsoid precession shows through clearly.

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

1988-01-01

130

Stabilizing torsional oscillations using a shunt reactor controller  

SciTech Connect

This paper presents the results of a study on the application of shunt reactors for the damping of torsional oscillations that occur in a power system containing series-capacitor compensation. The IEEE Second Benchmark Model, system-1 is employed to investigate the benefits of the utilization of modulated reactive power in suppressing unstable SSR modal interactions. A set of shunt reactor is connected to the generator bus of the affected synchronous machine whose shaft is directly coupled to the turbine system of the benchmark model. In order to stabilize all the torsional modes, a unified approach based on modal control theory is proposed for the design of a shunt reactor controller, which is essentially a dynamic output compensator. For demonstrating the effectiveness of the damping enhanced by the proposed scheme, eigenvalue analysis for different loading conditions, and sensitivity analysis for controller parameters are performed. In addition, dynamic responses of the nonlinear system under a three-phase short-circuit fault at infinite bus are also carried out. It can be concluded from the simulation results that the proposed shunt reactor control scheme can effectively suppress the torsional oscillations.

Wang, L.; Lee, C.H. (Inst. of Electrical Engineering, National Cheng Kung Univ., Tainan 70101 (TW))

1991-09-01

131

Sampling of conformation space in torsion angle dynamics calculations  

NASA Astrophysics Data System (ADS)

Torsion angle dynamics (TAD) performs molecular dynamics simulation using torsion angles instead of Cartesian coordinates as degrees of freedom. TAD algorithms used in conjunction with simulated annealing are one of the common methods for the calculation of three-dimensional protein structures from NMR data. For this application of TAD, unbiased sampling of conformation space is essential. This paper presents a systematic study of the sampling of conformation space in protein structure calculations with the TAD algorithm implemented in the program DYANA, and compares the results with those obtained with a different TAD algorithm in the program CNS. Examples used are unconstrained poly-alanine peptides of length 20 to 100 residues, and the globular protein Antennapedia(C39S) homeodomain, which comprises unstructured polypeptide segments at the two chain termini and was calculated from a high-quality experimental NMR data set. The results show that the different implementations of TAD all have good sampling properties for calculating protein structures that are well-constrained by experimental NMR data. However, if TAD is used for studies of long unconstrained polypeptides, the results obtained in this paper show that the molecule needs to reorient freely in space, and that the total angular and linear momenta of the system are conserved and periodically reset to zero.

Güntert, Peter; Wüthrich, Kurt

2001-08-01

132

Magnetic Torsional Oscillations in Magnetars  

SciTech Connect

We investigate torsional Alfven oscillations of relativistic stars with a global dipole magnetic field, via 2D numerical simulations. We find that a) there exist two families of quasi-periodic oscillations (QPOs) with harmonics at integer multiples of the fundamental frequency, b) the QPOs are long-lived, c) for the chosen form of dipolar magnetic field, the frequency ratio of the lower to upper fundamental QPOs is about 0.6, independent of the equilibrium model or of the strength of the magnetic field, and d) within a representative sample of EOS and of various magnetar masses, the Alfven QPO frequencies are given by accurate empirical relations that depend only on the compactness of the star and on the magnetic field strength. Compared to the observational frequencies, we also obtain an upper limit on the strength of magnetic field of SGR 1806-20 (if is dominated by a dipolar component) between {approx}3 and 7x10{sup 15} Gauss.

Sotani, Hajime [Theoretical Astrophysics, University of Tuebingen, 72076, Tuebingen (Germany); Kokkotas, Kostas D. [Theoretical Astrophysics, University of Tuebingen, 72076, Tuebingen (Germany); Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Stergioulas, Nikolaos [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece)

2009-05-01

133

Angular and axial deformities of the legs of children.  

PubMed

Age is often a determining factor in establishing a treatment program for these axial and angular problems. As can be seen, the deformities of torsion are noticeable from early life. Any tibial torsion should be treated early, but an excessive medial range of motion in the infant leg with a corresponding adequate lateral range of motion of the limb may be cautiously observed. Medial femoral torsion is a normal early finding in the infant thigh. The problem becomes evident as the child matures without the corresponding reduction in femoral torsion, leading to a persistence of fetal or infantile alignment. The gait consequences are usually noticed at 4 to 8 years of age. The angular changes generally are a delayed finding noticed in stance. The bowleg may be associated with marked tibial torsion and picked up early but the Blount's patient has been traditionally definable at 2 years of age. Levin and Drennan may hasten the time of diagnosis with their radiographic criteria. Knock-knee is an alignment disturbance noticed during the early to mid-childhood years, age 4 to 8 years. The diagnosis is important, differentiating physiologic from torsion-related deformities, and treatment, if warranted, should not be delayed. Generally the earlier these problems are discovered, the more optimistic the prognosis. Since the pediatric limb is in a constant state of transition, there will be a perpetual argument as to the need or efficacy of various approaches to the problems of knock-knee and bowleg. If observation is the treatment of choice, the percentage of cases which go on to osteotomies and epiphyseal stapling will continue. For those with axial or angular deformities, degenerative arthritis of the knee may be forthcoming. Swanson, Greene, and Allis warned of problems becoming "unphysiologic." If we consider the epiphyseal malleability, not only to deformity but to correction, we can appreciate Lenoir's comment of "every day the problem goes untreated is a golden opportunity lost forever." Early, gentle conservative therapy, using splints and casting, is an approach which should be considered in appropriate early problems. PMID:6536411

McDonough, M W

1984-12-01

134

Theoretical rotation-torsion energies of HSOH.  

PubMed

The rotation-torsion energies in the electronic ground state of HSOH are obtained in variational calculations based on a newly computed ab initio CCSD(T)/aug-cc-pV(Q+d)Z potential energy surface. Using the concept of the reaction path Hamiltonian, as implemented in the program TROVE (theoretical rovibrational energies), the rotation-vibration Hamiltonian is expanded around geometries on the torsional minimum energy path of HSOH. The calculated values of the torsional splittings are in excellent agreement with experiment; the root-mean-square (rms) deviation is 0.0002 cm(-1) for all experimentally derived splittings (with J < or = 40 and K(a) < or = 4). The model provides reliable predictions for splittings not yet observed. The available experimentally derived torsion-rotation term values (with J < or = 40 and K(a) < or = 4) are reproduced ab initio with an rms deviation of 1.2 cm(-1) (0.7 cm(-1) for J < or = 20), which is improved to 1.0 cm(-1) (0.07 cm(-1) for J < or = 20) in an empirical adjustment of the bond lengths at the planar trans configuration. The theoretical torsional splittings of HSOH are analyzed in terms of an existing semiempirical model for the rotation-torsion motion. The analysis explains the irregular variation of the torsional splittings with K(a) that has been observed experimentally. PMID:19045200

Ovsyannikov, Roman I; Melnikov, Vladlen V; Thiel, Walter; Jensen, Per; Baum, Oliver; Giesen, Thomas F; Yurchenko, Sergei N

2008-10-21

135

[Testicular torsion: experience with 28 cases].  

PubMed

The present study reports our experience in 28 cases of testicular torsion that had been treated at the Emergency Service of our hospital. The following parameters were analyzed: patient age, compromised side, torsion type, history of previous episodes, associated disorders and treatment. We underscore the importance of diagnosing the condition early based on patient history, clinical features and by Doppler ultrasound. Once the diagnosis has been made or when torsion is suspected, surgical intervention is advised to salvage testes compromised by this vascular accident. PMID:2291677

Jara Rascón, J; Díez Cordero, J M; Moncada Iribarren, I; Herranz Amo, F; Hernández Fernández, C; Pardo de Unceta, E

1990-10-01

136

Modification of gravity due to torsion  

SciTech Connect

Modifications of general relativity have been considered as one of the possible ways of addressing some of the outstanding problems related to the large scale gravitational physics. In this contribution we review some of the recent results which are due to the inclusion of dynamical torsion. More specifically we shall discuss the propagation of massive spin-2 particles in flat and curved space times. We shall show that, contrary to what is generally believed, spinning matter is not the sole source of torsion field. A symmetric energy momentum tensor can also couple to torsion degrees of freedom. The massive and massless spin-2 particles mix giving rise to an infrared modification of gravity.

Nair, V. P. [Physics Department, City College of the CUNY, New York, NY 10031 (United States); Nikiforova, V. [Physics Department, Mascow State University Moscow (Russian Federation); Randjbar-Daemi, S. [The Abdus Salam International Centre for Theoretical Physics, Trieste (Italy); Rubakov, V. [Institute for Nuclear Research of the Russian Academy of Sciences, Moscow (Russian Federation)

2010-01-01

137

Torsion of wandering spleen and distal pancreas  

SciTech Connect

Wandering spleen is the term applied to the condition in which a long pedicle allows the spleen to lie in an abnormal location. Torsion of a wandering spleen is an unusual cause of an acute abdomen and is rarely diagnosed preoperatively. Associated torsion of the distal pancreas is even more uncommon. The authors describe a patient with torsion of a wandering spleen and distal pancreas, who was correctly diagnosed, and define the merits of the imaging methods used. The initial examination should be /sup 99//sup m/Tc-sulfur colloid liner-spleen scanning.

Sheflin, J.R.; Lee, C.M.; Kretchmar, K.A.

1984-01-01

138

Angular Acceleration without Torque?  

ERIC Educational Resources Information Center

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.

Kaufman, Richard D.

2012-01-01

139

[Testicular torsion: review of 42 cases].  

PubMed

Forty two cases of Testicular Torsion in children aged under 9 are presented. Diagnosis and therapy are discussed; an accurate and prompt diagnosis is emphasized on to decide on the proper surgical correction to achieve testes preservation. PMID:3671956

Pérez Martínez, A; Bento, L

1987-01-01

140

Computational Investigation of Subsonic Torsional Airfoil Flutter.  

National Technical Information Service (NTIS)

In this thesis single-degree-of-freedom torsional airfoil flutter is investigated using an incompressible potential flow code, a compressible inviscid Euler code and a compressible viscous Navier-Stokes code. It is found that the classical linearized inco...

C. Kakkavas

1998-01-01

141

Torsional Pendulum Study on Several Rubber Compounds.  

National Technical Information Service (NTIS)

The goal of this investigation was to determine the shear properties on various rubber compounds using a low frequency (approximately equal to 1 Hz) measurement - torsional pendulum (TP) - to determine the damping and modulus as a function of temperature ...

G. F. Lee

1977-01-01

142

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)

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.

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

1983-01-01

143

Free vibrational analysis of axially loaded bending-torsion coupled beams: a dynamic finite element  

Microsoft Academic Search

In this article, a dynamic finite element formulation for the free vibration analysis of axially loaded bending-torsion coupled beams is presented. Based on the Euler–Bernoulli and St. Venant beam theories, the exact solutions of the differential equations governing the uncoupled vibrations of an axially loaded uniform beam are found. Then, employing these solutions as basis functions, the analytical expressions for

S. Mohammad Hashemi; Marc J. Richard

2000-01-01

144

[Torsion of the hydatid of Morgagni].  

PubMed

The authors present 6 cases of torsion of Morgagni's hydatid treated in the Emergency Urology Department over a two-year period. They stress the importance of the clinical diagnosis, as well as the differential diagnosis with other "acute, testicular bag" processes, in particular with funicular torsion. Surgical treatment is the only way of overcoming the pain, confirming the diagnosis and preventing the risk of secondary, testicular atrophy. PMID:7396562

Guillén Navarro, M; Ferrutxe Frau, J; Fernández Rodríguez, A; Alonso Gorrea, M; Gallego Gómez, J; Valls Blasco, F

1980-01-01

145

Stepping-Motor Drive Suppresses Torsional Oscillation  

NASA Technical Reports Server (NTRS)

Excitation in stepping-motor drive differs from conventional excitation in that each step is divided into two equal smaller steps separated by small interval, tau. Interval chosen to equal half period of torsional oscillation, so second step excitation equal in amplitude but opposite in phase to first step excitation. Thus, although first step unavoidably excites torsional oscillation, second step deexcites oscillation at end of first half cycle.

Bhat, Mahabaleshwar K. P.

1995-01-01

146

Flow in a torsionally oscillating filled cylinder  

NASA Technical Reports Server (NTRS)

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.

Schafer, C. F.

1983-01-01

147

Anisotropic angular distribution of sputtered atoms  

NASA Astrophysics Data System (ADS)

The sputtering yield angular distributions have been calculated on the basis of the ion energy dependence of total sputtering yields for Ni and Mo targets bombarded by low-energy Hg+ ions. The calculated curves show excellent agreement with the corresponding Wehner's experimental results of sputtering yield angular distributions. This fact clearly demonstrates the intrinsic relation between the ion energy dependence of total sputtering yields and the sputtering yield angular distribution. This intrinsic relation had been ignored in Yamamura's papers [Yamamura, Y. (1982). Theory of sputtering and comparison to experimental data, Nucl. Instr. and Meth. , 194 , 515-522; Yamamura, Y. (1981). Contribution of anisotropic velocity distribution of recoil atoms to sputtering yields and angular distributions of sputtered atoms, Rad. Eff. , 55 , 49-55.] due to some obvious mistakes.

Zhang, Z. L.; Zhang, L.

2004-05-01

148

Ocular torsion on earth and in weightlessness  

NASA Technical Reports Server (NTRS)

Otolith function is studied by means of measurements of ocular torsion under various acceleration environments on earth and in weightlessness. Photographic measurements of ocular torsion as indicated by the rotation of landmarks on the iris with respect to head-fixed fiducial marks were obtained in subjects undergoing horizontal linear acceleration in a ground-based version of the space sled, lateral acceleration from weightlessness during pullout from the free-fall portion of parabolic flight, and optokinetic stimulation about the roll axis in the supine position in the laboratory and during weightlessness. The responses of ocular torsion to horizontal acceleration are in agreement with a simple low-order linear system with a dominant time constant of 0.33 sec, with a transfer function fit by a model with a pure delay of 0 to 400 msec and a first-order lag. In the pullout experiment, torsion was not observed in response to the onset of acceleration in the right-ear-down position, although it was present in response to the lateral stimulus. Results of the roll vection experiments indicate the independence of ocular torsion and visually induced tilt. In addition, an automatic video system using a soft contact lens target is presented which has been developed for ocular torsion measurements.

Young, L. R.; Lichtenberg, B. K.; Arrott, A. P.; Crites, T. A.; Oman, C. M.; Edelman, E. R.

1981-01-01

149

The Torsional Fundamental Band of Methylformate  

NASA Astrophysics Data System (ADS)

Methylformate (HCOOCH_3) is one of the most important molecules in astrophysics, first observed in 1975. The rotational structure of its ground and first excited torsional states are well known from millimeter wave measurements. However, some of the torsional parameters are still not precisely determined because information on the torsional vibrational frequency v_t = 1-0 is missing. To overcome that problem, the far infrared spectrum of HCOOCH_3 was recorded with a 150 m optical path in a White cell and a Bruker IFS 125 HR Fourier transform spectrometer at the AILES beamline of the synchrotron SOLEIL facility. The analysis of the very weak fundamental torsional band v_t = 1-0 observed around 130 Cm-1 was carried out. It led to the first precise determination of the torsional barrier height and the dipole moment induced by the torsional motion. This work is partly supported by the "Programme National de Physico-Chimie du Milieu Interstellaire" (PCMI-CNRS) and by the contract ANR-BLAN-08-0054. R.D. Brown, J.G. Crofts, P.D. Godfrey, F.F. Gardner, B.J. Robinson, J.B. Whiteoak, Astrophys. J. 197 (1975) L29-L31. See V. Ilyushin, A. Kryvda, E. Alekseev, J. Mol. Spectrosc. 255 (2009) 32-38, and references therein.

Tudorie, M.; Ilyushin, V.; Vander Auwera, J.; Pirali, O.; Roy, P.; Huet, T. R.

2011-06-01

150

Motor effect in electron transport through a molecular junction with torsional vibrations  

NASA Astrophysics Data System (ADS)

We propose a model for a molecular junction with internal anharmonic torsional vibrations interacting with an electric current. The Wangsness-Bloch-Redfield master equation approach is used to determine the stationary reduced density matrix of the molecule. The dependence of the current, excitation energy, and angular momentum of the junction on the applied voltage is studied. Negative differential conductance is observed in the current-voltage characteristics. It is shown that a model with vibrationally dependent coupling to the electrodes, asymmetric with respect to the interchanging of electrodes, leads to a strong correlation between the applied voltage and the angular momentum of the junction. The model thus works as a molecular motor, with the angular momentum controlled by the size and sign of the voltage.

Pshenichnyuk, Ivan A.; ?ížek, Martin

2011-04-01

151

Hole-vibronic coupling in oligothiophenes: impact of backbone torsional flexibility on relaxation energies.  

PubMed

Density functional theory calculations together with highly resolved gas-phase ultraviolet photoelectron spectroscopy have been applied to oligothiophene chains with up to eight thiophene rings. One of the important parameters governing the charge transport properties in the condensed phase is the amount of energy relaxation upon ionization. Here, we investigate the impact on this parameter of the backbone flexibility present in oligothiophenes as a result of inter-ring torsional motions. With respect to oligoacenes that are characterized by a coplanar and rigid backbone, the torsional flexibility in oligothiophenes adds to the relaxation energy and leads to the broadening of the first ionization peak, making its analysis more complex. PMID:17428767

Filho, Demetrio A da Silva; Coropceanu, Veaceslav; Fichou, Denis; Gruhn, Nadine E; Bill, Tonja G; Gierschner, Johannes; Cornil, Jérôme; Brédas, Jean-Luc

2007-06-15

152

Angular velocity measuring interferome.  

PubMed

A novel optical system to measure angular velocity based on the Doppler effect is presented. The system was developed to investigate the effect of rotation in the process of experimental modal analysis. PMID:20555859

Ben-Levy, M; Braun, S G; Shamir, J

1989-10-15

153

Sharpening An Angular Cutter.  

National Technical Information Service (NTIS)

The video describes how to choose the correct grinding wheel, adjust the swivel table for grinding the angular teeth of the cutter, adjust for clearance angle, and check the teeth for accuracy of the angle.

1994-01-01

154

Cracked shells under skew-symmetric loading. [Reissner theory  

NASA Technical Reports Server (NTRS)

The general problem of a shell containing a through crack in one of the principal planes of curvature and under general skew-symmetric loading is considered. By employing a Reissner type shell theory which takes into account the effect of transverse shear strains, all boundary conditions on the crack surfaces are satisfied separately. Consequently, unlike those obtained from the classical shell theory, the angular distributions of the stress components around the crack tips are shown to be identical to the distributions obtained from the plane and anti-plane elasticity solutions. Results are given for axially and circumferentially cracked cylindrical shells, spherical shells, and toroidal shells under uniform in-plane shearing, out of plane shearing, and torsion. The problem is formulated for specially orthostropic materials, therefore, the effect of orthotropy on the results is also studied.

Delale, F.

1981-01-01

155

Angular velocity discrimination  

NASA Technical Reports Server (NTRS)

Three experiments designed to investigate the ability of naive observers to discriminate rotational velocities of two simultaneously viewed objects are described. Rotations are constrained to occur about the x and y axes, resulting in linear two-dimensional image trajectories. The results indicate that observers can discriminate angular velocities with a competence near that for linear velocities. However, perceived angular rate is influenced by structural aspects of the stimuli.

Kaiser, Mary K.

1990-01-01

156

Advances in Instrumentation and Technique of Torsional Pendulum and Torsional Braid Analyses.  

National Technical Information Service (NTIS)

A torsional pendulum which operates throughout the temperature range -180 to +650C, and permits the examination of specimens which conform to ASTM standard D2236 is reported. The same apparatus is used for torsional braid analyses for which a composite sp...

J. K. Gillham M. B. Roller

1971-01-01

157

Analytical procedure for modelling recursively and wire by wire stranded ropes subjected to traction and torsion loads  

Microsoft Academic Search

The aim of this article is to introduce a new theoretical procedure for modelling wire ropes subjected simultaneously to tensile and torsional loads. The procedure is based upon the beam assumption and takes account wire by wire of the double helical wires on the basis of general thin rod theory developed by [Love, A., 1944. Mathematical Theory of Elasticity. Dover

H. Usabiaga; J. M. Pagalday

2008-01-01

158

Representations of SO(3) and angular polyspectra  

Microsoft Academic Search

We characterize the angular polyspectra, of arbitrary order, associated with isotropic fields defined on the sphere S2 = ? (x, y, z) : x2 + y2 + z2 = 1 ? . Our techniques rely heavily on group representation theory, and specifically on the properties of Wigner matrices and Clebsch-Gordan coefficients. The findings of the present paper constitute a basis

Domenico Marinucci; Giovanni Peccati

2010-01-01

159

Entanglement of angular momenta of atoms and molecules  

NASA Astrophysics Data System (ADS)

In this article, we investigate the entanglement degrees of angular momenta of atoms and molecules. We demonstrate theoretically and numerically the guidelines, how to prepare maximally entangled states and how the entanglement of the angular momenta changes by changing the quantum numbers of atoms and molecules. We show that the entanglement degree reduces to the Clebsch-Gordan coefficients frequently encountered in angular momentum theory. The maximally entangled states found in this manner are useful for quantum computers and quantum information science.

Mishima, K.; Yamashita, K.

160

The Torsional Rigidity of Twist-Storing Polymers  

NASA Astrophysics Data System (ADS)

The statistical mechanics of a torsionally constrained polymer is investigated. We consider an inextensible chain with bend rigidity A and twist rigidity C. Through the relation Lk = Tw + Wr, the bend fluctuations must respond to an applied torque. We investigate this response and find excellent agreement between the predictions of our model and the experimental results on single ?-DNA molecules due to Strick et al. [Science 271 (1996) 1835]. This analysis affords an experimental determination of the microscopic twist rigidity C. Quantitative agreement between theory and experiment is obtained using C=120 nm. The theory further predicts a thermal reduction of the twist rigidity C induced by bend fluctuations. A confirmation of this result awaits further experiments.

Moroz, J. David; Nelson, Philip

1998-03-01

161

Omental Infarction due to Omental Torsion  

PubMed Central

Omental torsion is a rare cause of acute abdomen and sometimes requires surgery. Recently, we encountered a case of omental torsion diagnosed as omental infarction preoperatively. An 18-year-old male presented to our emergency room with a chief complaint of lower abdominal pain since previous 2 days. Because of his history of Down syndrome, an abdominal examination was very difficult. Plain abdominal computed tomography (CT) suggested omental hernia adhering to the right paracolic gutters. Two days after hospital admission, symptoms did not improve, and contrast-enhanced abdominal CT suggested omental infarction. We performed an emergency surgery. Upon exploration of the abdominal cavity, the greater omentum was found to be twisted four times and adhered to the right paracolic gutters. We performed a partial omentectomy. He was discharged 9 days after the surgery. There was no cause of omental torsion in the abdominal cavity, and he was diagnosed as having idiopathic omental torsion. In cases wherein the cause of acute abdomen cannot be detected, omental torsion should be considered, and abdominal CT could be helpful for the diagnosis.

Honjo, Kunpei; Nasu, Motomi; Fujisawa, Minoru

2013-01-01

162

Angular momentum radio  

NASA Astrophysics Data System (ADS)

Wireless communication amounts to encoding information onto physical observables carried by electromagnetic (EM) fields, radiating them into surrounding space, and detecting them remotely by an appropriate sensor connected to an informationdecoding receiver. Each observable is second order in the fields and fulfills a conservation law. In present-day radio only the EM linear momentum observable is fully exploited. A fundamental physical limitation of this observable, which represents the translational degrees of freedom of the charges (typically an oscillating current along a linear antenna) and the fields, is that it is single-mode. This means that a linear-momentum radio communication link comprising one transmitting and one receiving antenna, known as a single-input-single-output (SISO) link, can provide only one transmission channel per frequency (and polarization). In contrast, angular momentum, which represents the rotational degrees of freedom, is multi-mode, allowing an angular-momentum SISO link to accommodate an arbitrary number of independent transmission channels on one and the same frequency (and polarization). We describe the physical properties of EM angular momentum and how they can be exploited, discuss real-world experiments, and outline how the capacity of angular momentum links may be further enhanced by employing multi-port techniques, i.e., the angular momentum counterpart of linear-momentum multiple-input-multiple-output (MIMO).

Thidé, B.; Tamburini, F.; Then, H.; Someda, C. G.; Mari, E.; Parisi, G.; Spinello, F.; Romanato, F.

2014-02-01

163

Microstructural development of adiabatic shear bands in ultra-fine-grained low-carbon steels fabricated by equal channel angular pressing  

Microsoft Academic Search

Microstructural development of adiabatic shear bands formed in ultra-fine-grained low-carbon steels fabricated by equal channel angular pressing (ECAP) was investigated in this study. Dynamic torsional tests were conducted on four steel specimens, two of which were annealed after ECAP, using a torsional Kolsky bar. The ECAP’ed specimen consisted of fine equiaxed grains of 0.2?m in size, which were slightly coarsened

Byoungchul Hwang; Sunghak Lee; Yong Chan Kim; Nack J. Kim; Dong Hyuk Shin

2006-01-01

164

Transvaginal ovarian cystectomy for adnexal torsion during pregnancy.  

PubMed

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

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

2012-01-01

165

The Torsional Pendulum Test for Soils: A Theoretical Investigation.  

National Technical Information Service (NTIS)

A theoretical investigation of the torsional pendulum test for soils and its associated interpretation procedure is presented. By calculating the nonlinear, free-vibration response of knowing torsional testing systems, it was possible to examine the valid...

A. T. F. Chen

1980-01-01

166

Laser Deflection by a Torsionally Resonant Horn Loaded Piezoelectric Ceramic.  

National Technical Information Service (NTIS)

An ultrasonic laser deflector employing a torsionally oscillating piezoelectric transducer and mechanical transformer is described. A half-wave piezoelectric ceramic is cemented to a half-wave stepped horn to magnify the small amplitude torsional vibratio...

R. J. Klaiber

1967-01-01

167

Angular shear plate  

DOEpatents

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.

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

2009-07-14

168

Chronic liver lobe torsion in a cat.  

PubMed

A 13 yr old castrated male blue British shorthair with a 3 mo history of vomiting was diagnosed with a left lateral liver lobe mass following abdominal ultrasonography. At the time of celiotomy, liver lobe torsion (LLT) of the left lateral lobe was also present. Histopathologic evaluation of the liver mass and associated lobe revealed extensive necrosis secondary to chronic torsion. This is the second reported case of LLT in a cat. Both cases were associated with liver masses. The cat presented in this case remained clinically normal 8 mo postoperatively following lobectomy of the affected lobe. PMID:24446406

Nazarali, Alim; Singh, Ameet; Chalmers, Heather; Stevens, Brian; Plattner, Brandon L

2014-01-01

169

Clinical variants of idiopathic torsion dystonia.  

PubMed

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

Fahn, S

1989-06-01

170

Clinical variants of idiopathic torsion dystonia.  

PubMed Central

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.

Fahn, S

1989-01-01

171

Theories  

NSDL National Science Digital Library

This activity will help the students understand that science theories change in the face of new evidence, but those changes can be slow in coming. Students will observe how scientific theories change over time, Be introduced to the sophistication of the geocentric model and the time it took to change the theory underpinning the heliocentric model, Compare the heliocentric model to the geocentric model.

2010-01-01

172

Metamathematics of Ulm Theory  

Microsoft Academic Search

The classical Ulm theory provides a complete set of invariants for countable abelian p-groups, and hence also for countable torsion abelian groups. These invariants involve countable ordinals. One can read off many simple structural properties of such groups directly from the Ulm theory. We carry out a reverse mathematics analysis of several such properties. In many cases, we reverse to

Harvey M. Friedman

2001-01-01

173

A new method for torsional critical speed calculation of practical industrial rotors  

NASA Astrophysics Data System (ADS)

A new approach to calculating the torsional critical speed of rotors is presented. The governing equations for these speeds and the method of solutions differ from existing methods such as Holzer's, and the theory and numerical algorithm are straight forward, without any change in the field variables. The rotor studied has a distributed mass and rigid disks, and consists of many shaft segments of different diameters. The exact solution for undamped torsional motion of a uniform shaft segment is applied to a practical rotor-bearing system to generate the simultaneous governing equations for the torsional critical speeds. Within the framework of the theory, the set of governing equations is completely analytical and explicit, and it does not include any approximations, such as discretization of shaft mass and polynomial approximations. A computer program for the torsional critical speeds and the related mode shapes is developed by introducing a simple recurring numerical algorithm for a 3 by 4 submatrix in calculating the determinant generated by the simultaneous equations. The numerical algorithm essentially eliminates the necessity of constructing a huge matrix. The effectiveness of the new method is demonstrated in analyses of three rotors.

Jun, Oh-Sung; Kim, Paul Y.

1993-07-01

174

Structural Properties and Torsional Dynamics of Peroxides and Persulfides  

NASA Astrophysics Data System (ADS)

For the study of molecules containing O—O and S—S bonds, an analysis on the effect of level of theory and basis sets on electronic properties and geometrical parameters for H2O2 and H2S2 was done. Substitutions of one or both hydrogens in these molecules either by halogen atoms or alkyl groups were investigated for properties like geometries, dipole moments, cis and trans barriers. Attention has also been dedicated to the study of energy levels in the very anharmonic torsional potentials, obtaining their distributions as a function of temperature and partition functions for the torsional motion, of relevance for the isomerization rate leading to exchange between chiral enantiomers. Estimated rates both for underbarrier tunnelling and overbarrier transitions are consistently smaller for the S—S cases with respect to the corresponding O—O ones, due to the generally higher barriers. Regarding intermolecular interactions, of specific importance for collisional chirality exchange, an exploration was done for both H2O2- and H2S2-rare gases systems, extending the joint experimental and theoretical approach already tackled in this laboratory for interactions of H2O and H2S with the rare gases.

Maciel, Glauciete S.; Bitencourt, Ana Carla P.; Ragni, Mirco; Grossi, Gaia; Aquilanti, Vincenzo

175

PWM inverters producing torsional components in AC motors  

Microsoft Academic Search

Voltage source adjustable frequency drives produce voltage spectra capable of exciting torsional components within the bandwidth of a loadpsilas criticals. If not damped, a motorpsilas torsional spectrum may excite the mechanicalpsilas resonant frequencies destroying fan blades or fail couplings and shafts. This paper reports on an oil refinerypsilas induced draft fanpsilas coupling and drive motorpsilas shaft failures. Field torsional data,

Russel J. Kerkman; Jeff Theisen; Kirti Shah

2008-01-01

176

Tussive syncope in a pug with lung-lobe torsion  

PubMed Central

The most common presenting clinical signs of lung-lobe torsion include dyspnea, tachypnea, lethargy, and anorexia. Tussive syncope secondary to lung-lobe torsion has not been documented. This article describes the presentation, diagnosis, management, and outcome of a pug with tussive syncope secondary to lung-lobe torsion.

Davies, John A.; Snead, Elisabeth C.R.; Pharr, John W.

2011-01-01

177

$ L^2 $-torsion of Hyperbolic Manifolds of Finite Volume  

Microsoft Academic Search

.   Suppose is a compact connected odd-dimensional manifold with boundary, whose interior M comes with a complete hyperbolic metric of finite volume. We will show that the -topological torsion of and the -analytic torsion of the Riemannian manifold M are equal. In particular, the -topological torsion of is proportional to the hyperbolic volume of M, with a constant of proportionality

W. Lück; Thomas Schick

1999-01-01

178

Torsional Performance of Turbine Generator Shafts Especially Under Resonant Excitation  

Microsoft Academic Search

Interaction between the electrical transmission system and the turbine generator may induce torsional stresses to the shaft system whose magnitude and risk of damage have to be carefully analyzed in advance to ensure undisturbed operation and to preclude any damage from the unit. Within this task, the present paper investigates the torsional stressing which arise as a result of torsional

D. Lambrecht; T. Kulig

1982-01-01

179

Scaled angular spectrum method.  

PubMed

The angular spectrum method (ASM) calculates diffraction calculation in a high numerical aperture, unlike Fresnel diffraction. However, this method does not allow us to calculate at different sampling rates on source and destination planes. In this Letter, we propose a scaled ASM that calculates diffraction at different sampling rates on source and destination planes using the nonuniform fast Fourier transform. PMID:23027301

Shimobaba, Tomoyoshi; Matsushima, Kyoji; Kakue, Takashi; Masuda, Nobuyuki; Ito, Tomoyoshi

2012-10-01

180

Angular Talbot effect  

NASA Astrophysics Data System (ADS)

We predict the possibility of observing integer and fractional self-imaging (Talbot) phenomena on the discrete angular spectrum of periodic diffraction gratings illuminated by a suitable spherical wave front. Our predictions are experimentally validated, reporting what we believe to be the first observation of self-imaging effects in the far-field diffraction regime.

Azaña, José; Guillet de Chatellus, Hugues

2014-05-01

181

Angular momentum conservation demonstration  

NSDL National Science Digital Library

A short article describing the fabrication and operation of a simple angular momentum conservation demonstration. The demonstration is based on a Lazy Susan, and cylindrical brass weights tied with a nylon string. The string can be pulled or released changing the radius or rotation of the weights.

Berg, Richard E.; Anders, Robert E.

2010-12-23

182

Gears: Determining Angular Velocity  

NSDL National Science Digital Library

Students work as engineers and learn to conduct controlled experiments by changing one experimental variable at a time to study its effect on the experiment outcome. Specifically, they conduct experiments to determine the angular velocity for a gear train with varying gear ratios and lengths. Student groups assemble LEGO® MINDSTORMS® NXT robots with variously sized gears in a gear train and then design programs using the NXT software to cause the motor to rotate all the gears in the gear train. They use the LEGO data logging program and light sensors to set up experiments. They run the program with the motor and the light sensor at the same time and analyze the resulting plot in order to determine the angular velocity using the provided physics-based equations. Finally, students manipulate the gear train with different gears and different lengths in order to analyze all these factors and figure out which manipulation has a higher angular velocity. They use the equations for circumference of a circle and angular velocity; and convert units between radians and degrees.

AMPS GK-12 Program,

183

The OD, D geometry of string theory  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

184

A non-uniform warping theory for beams  

Microsoft Academic Search

This Note proposes a non-uniform warping beam theory including the effects of torsion and shear forces. Based on a displacement model using three warping parameters associated to three St Venant warping functions corresponding to torsion and shear forces, this theory is free from the classical assumptions on the warpings or on the shears, and is valid for any kind of

Rached El Fatmi

2007-01-01

185

[Torsion and seminoma in a cryptorchid testis].  

PubMed

Presentation of one case of seminoma on cryptorchid testicle which presented with torsion of spermatic cord clinically mimicking an inguinal incarcerated hernia. Despite the infrequency of the picture, the high association rate of neoplastic disease in cryptorchid testis which become twisted and force the adoption of oncological criteria for their treatment is highlighted. PMID:7915866

Torrús Tendero, P L; Merenciano Cortina, F J; Sánchez Marcos, M; Pelluch Auladell, A; García Tabar, P; Megias Garrigós, J; Mira Llinares, A

1994-05-01

186

Ricci recurrent space-times with torsion  

NASA Astrophysics Data System (ADS)

A Ricci recurrent space-time with covariantly constant stress tensor is an Einstein space-time. We extend this result to Ricci recurrent space-times with torsion. The result is applied to the case of Riemann-Cartan space-times with spin density.

Garcia de Andrade, L. C.

1991-02-01

187

Engine to dynamometer coupling - torsional vibration considerations  

Microsoft Academic Search

Couplings used for connecting engines to dynamometers can be subjected to torsional loads exceeding the design point unless precautions are implemented. The manufacturer's guidelines cannot alone predict a successful installation. A survey of the problems and solutions, as they apply to the modern high MEP engines, is presented. A wide range of testing speeds is possible with the appropriate combination

Jakub

1984-01-01

188

Torsional Strength of Longitudinals in Marine Structures.  

National Technical Information Service (NTIS)

Lateral-torsional instability (tripping) of stiffeners is often considered in design of marine structures to be only a secondary mode of failure. However, analytical studies and some tests have demonstrated that the mode has a serious potential of being t...

A. Ostapenko P. C. Chu

1986-01-01

189

Inheritance of idiopathic torsion dystonia among Jews  

Microsoft Academic Search

Idiopathic torsion dystonia (ITD) has long been considered to be genetically determined, but the pattern of inheritance has been unclear. It has been suggested that inheritance may differ in Jews and non-Jews. In the present study, data gathered in a nationwide survey of ITD in Israel were analysed. Between 1969 and 1980, 47 patients were collected, of whom 40 were

N Zilber; A D Korczyn; E Kahana; K Fried; M Alter

1984-01-01

190

Dispensing system eliminates torsion in deployed hoses  

NASA Technical Reports Server (NTRS)

Dispensing system uses a rotating drum, transfer arm, and stationary drum to deploy, reel in, and store an attached hose. This system which eliminates torsion and minimizes strain and wear of flexible hoses, is used for handling flexible cables that have one end permanently attached to an outlet or connector.

1965-01-01

191

Ovarian torsion: A fifteen-year review  

Microsoft Academic Search

Study Objective: Our purpose was to describe the history, physical, and laboratory findings in women with ovarian torsion (OT). Methods: A retrospective chart review was conducted at 2 urban teaching hospitals. All women admitted from 1984 to 1999 with surgically proven OT were included in the study. Results: The 87 women ranged in age from 14 to 82 years (mean

Debra Houry; Jean T. Abbott

2001-01-01

192

Adnexal torsion: review of the literature.  

PubMed

Adnexal torsion is one of a few gynecologic surgical emergencies. Misdiagnosis or delay in treatment can have permanent sequelae including loss of an ovary with effect on future fertility, peritonitis, and even death. A PubMed search was performed between 1985 and 2012 for reviews, comparative studies, and case reports to provide a review of the epidemiology, risk factors, clinical presentation, common laboratory and imaging findings, and treatments of adnexal torsion. Common symptoms of torsion include pain, nausea, and vomiting, with associated abdominal or pelvic tenderness, and may differ in premenarchal and pregnant patients. Laboratory and imaging findings including ultrasound with Doppler analysis, computed tomography, and magnetic resonance imaging can assist in making the diagnosis but should not trump clinical judgment; normal Doppler flow can be observed in up to 60% of adnexal torsion cases. Treatment depends on the individual patient but commonly includes detorsion, even if the adnexae initially seem necrotic, with removal of any associated cysts or salpingo-oophorectomy, because recurrence rates are higher with detorsion alone or detorsion with only cyst aspiration. PMID:24126258

Sasaki, Kirsten J; Miller, Charles E

2014-01-01

193

6H-SiC microdisk torsional resonators in a "smart-cut" technology  

NASA Astrophysics Data System (ADS)

We report on experimental demonstration of high frequency torsional resonators based on microdisk structures enabled by a "smart-cut" 6H-silicon carbide (6H-SiC) technology. Circular microdisks axially supported by pairs of thin tethers, with diameters of ˜5-15 ?m, exhibit torsional-mode micromechanical resonances with frequency of ˜1-60 MHz, and quality (Q) factors up to 1280 at room temperature in moderate vacuum (˜10 mTorr). Measured intrinsic thermomechanical vibrations of a microdisk with diameter d ? 15.9 ?m (and triangular cross-section tethers with width wT ? 1.5 ?m, length LT ? 2 ?m, and thickness tT ? 0.4 ?m) demonstrate a torque resolution of ST1/2 ? 3.7 × 10-20 (N m)/?Hz, a force sensitivity of SF1/2 ? 5.7fN/?Hz, and an angular displacement sensitivity of S?1/2 ? 4.0 × 10-8 rad/?Hz. By examining devices with varying disk size, different tether shape, width, and length, and by combining experimental data and theoretical calculations, we depict the scaling pathways for ultrasensitive torsional resonant sensors based on this smart-cut 6H-SiC platform.

Yang, Rui; Wang, Zenghui; Lee, Jaesung; Ladhane, Kalyan; Young, Darrin J.; Feng, Philip X.-L.

2014-03-01

194

Development of a second generation torsion balance based on a spherical superconducting suspension.  

PubMed

This paper describes the development of a second generation superconducting torsion balance to be used for a precision measurement of the Casimir force and a short range test of the inverse square law of gravity at 4.2 K. The instrument utilizes niobium (Nb) as the superconducting element and employs passive damping of the parasitic modes of oscillation. Any contact potential difference between the torsion balance and its surroundings is nulled to within approximately 50 mV by applying known DC biases and fitting the resulting parabolic relationship between the measured torque and the applied voltage. A digital proportional-integral-derivative servo system has been developed and characterized in order to control the azimuthal position of the instrument. The angular acceleration and displacement noise are currently limited by the capacitive sensor at the level 3x10(-8) rad s(-2)/ squarerootHz and 30 nm/ squarerootHz at 100 mHz. The possibility of lossy dielectric coatings on the surface of the torsion balance test masses is also investigated. Our measurements show that the loss angles delta are (1.5+/-2.3)x10(-4) and (2.0+/-2.2)x10(-4) at frequencies of 5 and 10 mHz, respectively. These values of loss are not significant sources of error for measurements of the Casimir force using this experimental setup. PMID:18315325

Hammond, Giles D; Speake, Clive C; Matthews, Anthony J; Rocco, Emanuele; Peña-Arellano, Fabian

2008-02-01

195

Angular Momentum Diagrams  

NASA Astrophysics Data System (ADS)

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.

Wormer, Paul E. S.; Paldus, Josef

196

Evaluation of left ventricular torsion by cardiovascular magnetic resonance  

PubMed Central

Recently there has been considerable interest in LV torsion and its relationship with symptomatic and pre-symptomatic disease processes. Torsion gives useful additional information about myocardial tissue performance in both systolic and diastolic function. CMR assessment of LV torsion is simply and efficiently performed. However, there is currently a wide variation in the reporting of torsional motion and the procedures used for its calculation. For example, torsion has been presented as twist (degrees), twist per length (degrees/mm), shear angle (degrees), and shear strain (dimensionless). This paper reviews current clinical applications and shows how torsion can give insights into LV mechanics and the influence of LV geometry and myocyte fiber architecture on cardiac function. Finally, it provides recommendations for CMR measurement protocols, attempts to stimulate standardization of torsion calculation, and suggests areas of useful future research.

2012-01-01

197

Torsional Pendulum Studies of HELIUM-4 in Nanopores  

NASA Astrophysics Data System (ADS)

In this dissertation, experimental results are presented on the torsion pendulum studies of ^4 He adsorbed in chabazite, whose pore is 13 A in diameter, and in silica with 25 A diameter pores. The objective of this work was to search for superfluidity in extremely confined ^4He. A novel technique for dehydrating chabazite crystals has been developed for this work. As we found out, chabazite crystals of millimeter sizes cannot be dehydrated simply by heating them in vacuum as commonly done for zeolite powders, since the heating results in pulverization of the crystals. To dehydrate the crystals without damage, a high pressure dehydration technique has been developed. In this method, chabazite crystals are heated in a high pressure helium atomosphere at pressures over 10,000 psi in a furnace attached to a sorption pump filled with activated charcoal. The pump removes water selectively under high pressure. Using a crystal prepared with this method, the experiment down to 100 mK found no superfluidity in ^4He adsorbed in chabazite crystal with the torsion pendulum technique. In porous silica, superfluid transition was observed with the transition temperature ranging from 0.12 K to 0.82 K depending on the ^4He coverage. Near the full pore coverage, the temperature dependence of the superfluid density was found to arise entirely from the phonon excitation, with no evidence for other mechanisms such as vortex-pair unbinding. The superfluid density for lower ^4He coverages are compared with the Kosterlitz-Thouless theory adopted by Kotsubo and Williams for a small sphere. The fitting parameters obtained from the comparison are examined to address the applicability of the Kosterlitz-Thouless theory to ^4He films in extreme confinement.

Miyamoto, Satoru

198

N{=} 4 mechanics with diverse (4, 4, 0) multiplets: Explicit examples of hyper-Kähler with torsion, Clifford Kähler with torsion, and octonionic Kähler with torsion geometries  

NASA Astrophysics Data System (ADS)

We present simple models of N{=} 4 supersymmetric mechanics with ordinary and mirror linear (4, 4, 0) multiplets that give a transparent description of Hyper-Kähler with Torsion (HKT), Clifford Kähler with Torsion (CKT), and Octonionic Kähler with Torsion (OKT) geometries. These models are treated in the N{ = } 4 and N{ = }2 superfield approaches, as well as in the component approach. Our study makes manifest that the CKT and OKT supersymmetric sigma models are distinguished from the more simple HKT models by the presence of extra holomorphic torsion terms in the supercharges.

Fedoruk, Sergey; Ivanov, Evgeny; Smilga, Andrei

2014-05-01

199

Continuous phase transition and critical behaviors of 3D black hole with torsion  

NASA Astrophysics Data System (ADS)

We study the phase transition and the critical behavior of the BTZ black hole with torsion obtained in (1 + 2)-dimensional Poincaré gauge theory. According to Ehrenfest’s classification, when the parameters in the theory are arranged properly, the BTZ black hole with torsion may possess the second-order phase transition which is also a smaller mass/larger mass black hole phase transition. Nevertheless, the critical behavior is different from the one in the van der Waals liquid/gas system. We also calculated the critical exponents of the relevant thermodynamic quantities, which are the same as the ones obtained in the Ho?ava-Lifshitz black hole and the Born-Infeld black hole.

Ma, Meng-Sen; Liu, Fang; Zhao, Ren

2014-05-01

200

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

NASA Astrophysics Data System (ADS)

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.

Malik, D. A.; Kimel, A. V.; Kirilyuk, A.; Rasing, Th.; van der Zande, W. J.

2010-04-01

201

Head and Tail Deformations, Torsional Coriolis Coupling, and E1 d-E2 d Vibrational Mixing in Ethane-Like Molecules  

NASA Astrophysics Data System (ADS)

The mechanism of torsional Coriolis interaction of E1 d and E2 d vibrational modes in ethane-like molecules is investigated, and it is shown that this coupling can drastically affect the torsional splitting in the degenerate vibrational states. A basic point of our treatment is that the sets of coordinates of head and tail which combine with the + sign to generate E1 d normal coordinates are in general different from those which combine with the - sign to generate E2 d normal coordinates. It is shown that the ? ? torsional Coriolis coefficients calculated by the usual methods of normal mode analysis are related to the vibrational angular momenta within head and tail referred to the internal rotor axis systems. With knowledge of the L and L-1 matrices it is possible to transform these coefficients for reference to the molecule-fixed frame. It is peculiar that torsional Coriolis matrix elements occur between E1 d and E2 d vibrational components with the same x or y orientation in the molecule-fixed frame. The matrix elements of the torsional Coriolis operator and other operators responsible for the end-to-end coupling are determined, and a method for calculating vibration-torsion energies, and then torsional splittings, in degenerate vibrational states is outlined. Detailed calculations require a global model, involving all the degenerate vibrational basis states in a complex mechanism of interactions, but it is shown that useful information can be obtained by means of simplified models. Our semiempirical rule that degenerate vibrational states with a large negative value of the diagonal vibration-rotation Coriolis coefficient are likely to deviate much from the behavior of E1 d or E2 d vibrational states, with a sensible decrease of the torsional splittings, is confirmed.

Lattanzi, F.; di Lauro, C.

1999-12-01

202

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

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

203

Effects of warping and pretwist on torsional vibration of rotating beams  

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

204

Metric-Scalar Gravity with Torsion and the Measurability of the Non-Minimal Coupling  

NASA Astrophysics Data System (ADS)

The "measurability" of the non-minimal coupling is discussed by considering the correction to the Newtonian static potential in the semiclassical 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.

Accioly, A.; Blas, H.

205

A preliminary study of a torsion balance based on a spherical superconducting suspension  

NASA Astrophysics Data System (ADS)

We present details of the design and construction of a new superconducting, magnetically suspended torsion balance in which the levitation coil and the lift surface of the float lie on the surfaces of concentric spheres. We compare results from calculations of the variation of the inductance with the levitated height and transverse motion of the float with experimental measurements and show that the levitation system is stable. Angular motion of the torsion balance is detected using superconducting pick-up coils whose inductance is modulated by float rotation. The subsequent change in current flowing in the persistent circuit containing the coils is measured using a flux-gate magnetometer. The pick-up coils exert a restoring torque on the float which can be modified by adjusting the persistent current stored. Periods down to 60 s should be obtainable for a current of 2.5 A. Preliminary results of ring-down experiments in He gas at a pressure of 53Pa show that periods of angular oscillations of 24 s with quality factor, Q, of about 200 can be obtained. The moment of inertia of the float is 2 × 10-5 kg m2. The observed period of 24 s indicates that there is an additional restoring torque in the system which may be due to trapped flux. The observed value of Q is consistent with gas damping.

Speake, C. C.; Hammond, G. D.; Trenkel, C.; Rochester, G. K.; Sumner, T. J.

1999-06-01

206

Selective preparation of enantiomers from a racemate by laser pulses: model simulation for oriented atropisomers with coupled rotations and torsions  

Microsoft Academic Search

We design a laser pulse which drives a racemate of oriented atropisomers at low temperature to a preferential target enantiomer. The overall laser pulse consists of a series of individual circularly polarized laser pulses which induce corresponding selective transitions between coupled rotational and torsional states. The underlying theory is derived in detail for a model system. It consists of two

K. Hoki; D. Kröner; J. Manz

2001-01-01

207

Two-Frequency Method for Asynchronous Machines Accounting for an Additional Synchronous Generator Capable of Torsional Vibrations.  

National Technical Information Service (NTIS)

The theory of an asynchronous machine fed according to the two-frequency method is treated by accounting for an additional synchronous generator capable of torsional vibrations and having a damping cage. The starting point of the calculations is a system ...

A. Freese

1980-01-01

208

Similitude study for a laminated cylindrical tube under tension, torsion, bending, internal and external pressure Part II: scale models  

Microsoft Academic Search

The aim of this study is to demonstrate the validity of scale model development testing and predict the laminated cylindrical tube behavior under tensile, torsion, bending, internal and external pressure load. Similitude theory is used to develop the necessary similarity conditions. In the amplitude approach, the coefficients of the governing differential equation for the prototype and the model of the

C. S. Chouchaoui; P. Parks; O. O. Ochoa

1999-01-01

209

A novel angular acceleration sensor based on the electromagnetic induction principle and investigation of its calibration tests.  

PubMed

An angular acceleration sensor can be used for the dynamic analysis of human and joint motions. In this paper, an angular acceleration sensor with novel structure based on the principle of electromagnetic induction is designed. The method involves the construction of a constant magnetic field by the excitation windings of sensor, and the cup-shaped rotor that cut the magnetic field. The output windings of the sensor generate an electromotive force, which is directly proportional to the angular acceleration through the electromagnetic coupling when the rotor has rotational angular acceleration. The mechanical structure and the magnetic working circuit of the sensor are described. The output properties and the mathematical model including the transfer function and state-space model of the sensor are established. The asymptotical stability of the sensor when it is working is verified by the Lyapunov Theorem. An angular acceleration calibration device based on the torsional pendulum principle is designed. The method involves the coaxial connection of the angular acceleration sensor, torsion pendulum and a high-precision angle sensor, and then an initial external force is applied to the torsion pendulum to produce a periodic damping angle oscillation. The angular acceleration sensor and the angle sensor will generate two corresponding electrical signals. The sensitivity coefficient of the angular acceleration sensor can be obtained after processing these two-channel signals. The experiment results show that the sensitivity coefficient of the sensor is about 17.29 mv/Krad·s2. Finally, the errors existing in the practical applications of the sensor are discussed and the corresponding improvement measures are proposed to provide effective technical support for the practical promotion of the novel sensor. PMID:23941911

Zhao, Hao; Feng, Hao

2013-01-01

210

A Novel Angular Acceleration Sensor Based on the Electromagnetic Induction Principle and Investigation of Its Calibration Tests  

PubMed Central

An angular acceleration sensor can be used for the dynamic analysis of human and joint motions. In this paper, an angular acceleration sensor with novel structure based on the principle of electromagnetic induction is designed. The method involves the construction of a constant magnetic field by the excitation windings of sensor, and the cup-shaped rotor that cut the magnetic field. The output windings of the sensor generate an electromotive force, which is directly proportional to the angular acceleration through the electromagnetic coupling when the rotor has rotational angular acceleration. The mechanical structure and the magnetic working circuit of the sensor are described. The output properties and the mathematical model including the transfer function and state-space model of the sensor are established. The asymptotical stability of the sensor when it is working is verified by the Lyapunov Theorem. An angular acceleration calibration device based on the torsional pendulum principle is designed. The method involves the coaxial connection of the angular acceleration sensor, torsion pendulum and a high-precision angle sensor, and then an initial external force is applied to the torsion pendulum to produce a periodic damping angle oscillation. The angular acceleration sensor and the angle sensor will generate two corresponding electrical signals. The sensitivity coefficient of the angular acceleration sensor can be obtained after processing these two-channel signals. The experiment results show that the sensitivity coefficient of the sensor is about 17.29 mv/Krad·s2. Finally, the errors existing in the practical applications of the sensor are discussed and the corresponding improvement measures are proposed to provide effective technical support for the practical promotion of the novel sensor.

Zhao, Hao; Feng, Hao

2013-01-01

211

[Torsion of the hydatid of Morgagni].  

PubMed

We present 22 cases of torsion of the hydatid of Morgagni, attended in our hospital in the space of seven years (1981-1988), which were subjected to emergency operation. The ages ranged from 6 months to 16 years, with an average age of 9 years. The typical symptomatology was the sudden appearance of acute pain, located most frequently in the left side, accompanied by vegetative symptoms, without the existence of fever and micturition syndrome. The most significant exploratory diagnostic element in torsion of the hydatid of Morgagni prior to surgery is the palpation of a painful nodule on the upper pole of the testicle and which corresponds to the twisted hydatid. We outline the guidelines for diagnosis and treatment used, emphasising the importance of early surgery as the means of suppressing the symptomatology and forestalling complications, besides confirming the diagnosis. PMID:2763886

Alcalá-Santaella Casanova, C; Salinas Sánchez, S; Moreno Avilés, J; Pérez Albacete, M; Server Falgás, A G

1989-01-01

212

[Spontaneous lung torsion after acute pleuropneumonia].  

PubMed

We report on a case of spontaneous torsion of the right lung in a 59 years old woman which occurred after an acute pneumonia followed by chronic empyema and progressive dyspnea with marked respiratory disability. Despite extensive diagnostic procedures including bronchoscopy and bronchography the true diagnosis could be established only by thoracotomy performed in order to cure the chronic empyema. The abnormal hilar rigidity by preexisting calcified sarcoidosis of the lymph-nodes is suggested to be a major risk factor for developing lung torsion as it has been emphasized in a few similar reports from the literature. Surgical reposition of the displaced lung is the most effective treatment and can save and restitute lung structure and function even in patients with prolonged course and delayed diagnosis. PMID:1494581

Hufschmid, P; Keller, R; Aeberhard, P

1992-12-01

213

Self-oscillations in nonlinear torsional metamaterials  

NASA Astrophysics Data System (ADS)

We study the nonlinear dynamics of torsional meta-molecules—sub-wavelength resonators with strong coupling between electromagnetic excitation and rotational deformation—and show that such structures may undergo self-oscillations. We develop a semi-analytical model to evaluate the electromagnetic-elastic coupling in such structures. By analysing the local stability of the system, we reveal two different mechanisms leading to self-oscillations. Contrary to many previously studied optomechanical systems, self-oscillations of torsional meta-molecules can be extremely robust against mechanical damping. Due to the chiral nature of the structure, a consequence of self-oscillations in this system is dynamic nonlinear optical activity, which can be actively controlled by a range of parameters such as the field strength and polarization of the incident wave.

Liu, M.; Powell, D. A.; Shadrivov, I. V.; Lapine, M.; Kivshar, Y. S.

2013-07-01

214

Design of Torsion Flexures for MEMS Bearings  

Microsoft Academic Search

Abstract-The design of microelectrom echanical systems (MEMS) devices that assemble or move outside the wafer plane requires the development of sele ctively compliant load carrying mechanisms. We,present an analysis and design of a torsion bearing fabricated in the Iolanthe process (combination of SOI with polysilicon surface micromachining).Modeling results indicate that a viable and,robust design is,possible within the process and application

Jeanne Casstevens; Jevan Furmanski

215

Torsional Response of Structure with Mass Eccentricity  

Microsoft Academic Search

\\u000a Base isolation is found effective in reducing torsional response of structures with mass eccentricity when subjected to earthquakes.\\u000a In this study, dynamic characteristics of an eccentric five-storey benchmark model, isolated with laminated rubber bearings\\u000a (LRB) and lead core rubber bearings (LCRB), were examined using a shaker table and four different ground motions. The earthquake-resistant\\u000a performance of LRB and LCRB isolators

Helen Wu

216

UBIQUITOUS TORSIONAL MOTIONS IN TYPE II SPICULES  

SciTech Connect

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.

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

217

An Evaluation of the Double Torsion Technique  

Microsoft Academic Search

Double Torsion (DT) is a powerful testing technique for fracture mechanics characterisation of brittle materials as, in principle,\\u000a it provides a crack length independent test configuration. However, several corrections have been proposed to address variations\\u000a of experimental results reported from various laboratories. These correction factors address the validity of the DT configuration\\u000a and its crack length independent stress intensity. Never

T. H. Becker; T. J. Marrow; R. B. Tait

218

Fluid driven torsional dipole seismic source  

DOEpatents

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.

Hardee, Harry C. (Albuquerque, NM)

1991-01-01

219

Analytic Model for the Rototranslational Torsion Pendulum  

NASA Astrophysics Data System (ADS)

We develop an analytic model to describe the motion of the RotoTranslational Torsion Pendulum PETER in a wide range of frequencies (from 1mHz up to 10-15Hz). We also try to explain some unexpected features we found in the data with only 1 soft degree of freedom and we estimate values for the misalignment angles and other parameters of the model.

De Marchi, F.; Bassan, M.; Pucacco, G.; Marconi, L.; Stanga, R.; Visco, M.

2013-01-01

220

Surgical correction of idiopathic medial femoral torsion  

Microsoft Academic Search

Summary  We reviewed 28 hips in 14 patients with severe bilateral idiopathic medial femoral torsion which had been corrected by intertrochanteric\\u000a rotation osteotomy using crossed pins for fixation and a hip spica. There were 10 girls and 4 boys with a mean age of 7 years\\u000a and 9 months. All had functional and cosmetic disability before operation. The average follow up

J. S. Shiml; L. T. Staheli; B. N. Holm

1995-01-01

221

Balanced angular profile analysis.  

PubMed

To evaluate current preferences and ethnic differences of female soft-tissue profiles, 71 profile photographs of famous female models were collected from Internet Web pages and divided into four groups (Korean, 22; Japanese, 15; Chinese, 16; and Western, 18). Eleven soft-tissue landmarks were recorded on each photograph and 16 angular measurements were made by using V-ceph (CyberMed, Inc., Seoul, Korea). Data from each group are presented to show the means, ranges, p and F values, standard deviations, and standard errors of each measurement. In addition, individual measurements for each group were compared with those of the other groups by one-way analysis of variance using a p value corrected for multivariable testing. Between-group mean value differences were calculated using a Tukey's studentized range test (HSD), at a significance level of p = 0.05. Most of the variables were similar in the groups. Significant between-group differences (p < 0.05) were found for angle of alar curvature point, profile convexity, interlabial contour, and nasolabial contour. In addition, we divided all data into two groups (Western and Asian). The t test (with significance level set to p = 0.05) was performed to compare the two. Significant between-group differences (p < 0.05) were found for angle of alar curvature, angle of labiale inferius, profile convexity, and lower lip projection angle, but no significant racial differences were found in terms of several profile angles. These findings suggest that point of ala curvature point, subnasale, and the labiale inferius of Asian models may differ from those of Western models. These peculiar angular patterns of Asian models led the authors to create a new characteristic angular concept, termed the "ethnic pyramid," which is composed of soft-tissue profile points of alar curvature point, subnasale, pronasale, and labiale inferius. This ethnic pyramid describes the characteristic patterns of the ethnic differences. The results of this study suggest that the soft-tissue profiles of famous female models have some common features but also show differences among ethnic groups and races. This simple method of profile analysis may provide aesthetic surgeons with a simple formula and reference data for creation and application of an attractive face. On the basis of their balanced angular profile analysis data, the authors suggest that appropriate and harmonious aesthetic operations reflecting these differences should be considered. PMID:15277828

Rhee, Seung Chul; Kang, So Ra; Park, Heung Sik

2004-08-01

222

Fundamentals of IC engine torsional vibration  

SciTech Connect

Fluctuations in IC engine cylinder pressure are an obvious source of torsional vibration excitation, although the details of the coupling from cylinder pressure to torque on the crankshaft are complicated. A second, less obvious source of torsional excitation is the effect of variable inertia associated with the engine slider-crank mechanism. This is a tutorial paper, intended to show the relation between, on the one hand, the actual engine slider-crank mechanism subject to combustion gas pressure and, on the other hand, the models commonly used for torsional vibration analysis that involve constant inertias subject to torques expressed by Fourier series. As such, it uses some new approaches to reach previously known results with a greater degree of physical insight. The presentation is in terms of a single cylinder, two stroke engine with load, and makes clear the roles of piston mass, connecting rod mass and moment of inertia, and crank inertia as they affect both the effective inertia and the effective torque. The determination of natural frequencies and the forced vibration response calculation are briefly described to complete the analysis. The development of a Fourier series representation for the effective torque, including both the cylinder pressure and inertia variation is also discussed. The various components for the response are identified, in an effort to clarify the meaning of terms such as ''zero frequency mode,'' ''rigid body mode,'' and ''twisting mode.''

Doughty, S.

1988-01-01

223

Noncommutative Gauge Theory with Covariant Star Product  

SciTech Connect

We present a noncommutative gauge theory with covariant star product on a space-time with torsion. In order to obtain the covariant star product one imposes some restrictions on the connection of the space-time. Then, a noncommutative gauge theory is developed applying this product to the case of differential forms. Some comments on the advantages of using a space-time with torsion to describe the gravitational field are also given.

Zet, G. [Physics Department, 'Gh. Asachi' Technical University, 700050 Iasi (Romania)

2010-08-04

224

Triply coupled bending-torsion vibration of Timoshenko and Euler-Bernoulli shaft beams with arbitrarily oriented open crack  

NASA Astrophysics Data System (ADS)

The paper presents the full formulation for a crack model for analyzing the triply coupled free vibration of both Timoshenko (short) and Euler-Bernoulli (long) shaft beams based on compliance approach in the presence of a planar open edge crack in an arbitrary angular orientation with a reference direction. The compliance coefficients to account for the local flexibility due to the crack for both the beams have been obtained through the concept of strain energy release rate and crack tip stress field given in terms of the stress intensity factors. The type of disturbance in stress-strain field that a continuous cracked beam theory can accommodate is not within the scope of the model. The compliance matrices for the Timoshenko (short) and Euler-Bernoulli (long) beams, respectively, are of size 6×6 and 3×3, and they consist of only 9 and 4 nonzero coefficients. The variation of the coefficients with crack orientation is presented. Equations governing the free transverse and torsion vibrations are derived and solved in both the cases. The formulation has been checked by comparing the theoretical frequencies with the finite element results for a few crack orientations, locations and depths. The agreement is good. It is shown further that, when such cases are analysed for studying the transverse vibration only in one plane by invoking a single rotational spring at the crack location, the approach leads to an erroneous variation of the frequencies with the crack orientations. The data presented here will be useful to solve both forward and inverse problems.

Naik, Sachin S.; Maiti, Surjya K.

2009-07-01

225

Resonance method of measuring shear viscoelastic properties of liquid media based on excitation of torsional oscillations in tubes  

NASA Astrophysics Data System (ADS)

Possibilities of using torsional oscillations for measuring viscoelastic properties of liquids are discussed. The theory of torsional oscillations of an elastic tube filled with the media to be investigated possessing viscosity and shear elasticity is developed. It is shown that to determine a complex shear modulus it is sufficient to determine the resonance frequency and Q-factor of torsional oscillations. An experimental installation and the results of measurements of viscoelastic modulus of glycerin and oil of one oilfield within the temperature range from -10° to 60°C are given. The experimental installation allows measuring a viscoelastic modulus within the range of acoustic logging frequencies (10-20 kHz). The obtained results are compared with the results of rheometric measurements.

Esipov, I. B.; Zozulya, O. M.; Fokin, A. V.

2010-01-01

226

Accurate description of torsion potentials in conjugated polymers using density functionals with reduced self-interaction error  

NASA Astrophysics Data System (ADS)

We investigate the torsion potentials in two prototypical ?-conjugated polymers, polyacetylene and polydiacetylene, as a function of chain length using different flavors of density functional theory. Our study provides a quantitative analysis of the delocalization error in standard semilocal and hybrid density functionals and demonstrates how it can influence structural and thermodynamic properties. The delocalization error is quantified by evaluating the many-electron self-interaction error (MESIE) for fractional electron numbers, which allows us to establish a direct connection between the MESIE and the error in the torsion barriers. The use of non-empirically tuned long-range corrected hybrid functionals results in a very significant reduction of the MESIE and leads to an improved description of torsion barrier heights. In addition, we demonstrate how our analysis allows the determination of the effective conjugation length in polyacetylene and polydiacetylene chains.

Sutton, Christopher; Körzdörfer, Thomas; Gray, Matthew T.; Brunsfeld, Max; Parrish, Robert M.; Sherrill, C. David; Sears, John S.; Brédas, Jean-Luc

2014-02-01

227

Accurate description of torsion potentials in conjugated polymers using density functionals with reduced self-interaction error.  

PubMed

We investigate the torsion potentials in two prototypical ?-conjugated polymers, polyacetylene and polydiacetylene, as a function of chain length using different flavors of density functional theory. Our study provides a quantitative analysis of the delocalization error in standard semilocal and hybrid density functionals and demonstrates how it can influence structural and thermodynamic properties. The delocalization error is quantified by evaluating the many-electron self-interaction error (MESIE) for fractional electron numbers, which allows us to establish a direct connection between the MESIE and the error in the torsion barriers. The use of non-empirically tuned long-range corrected hybrid functionals results in a very significant reduction of the MESIE and leads to an improved description of torsion barrier heights. In addition, we demonstrate how our analysis allows the determination of the effective conjugation length in polyacetylene and polydiacetylene chains. PMID:24511943

Sutton, Christopher; Körzdörfer, Thomas; Gray, Matthew T; Brunsfeld, Max; Parrish, Robert M; Sherrill, C David; Sears, John S; Brédas, Jean-Luc

2014-02-01

228

Pull-in study of an electrostatic torsion microactuator  

Microsoft Academic Search

Pull-in study of an electrostatic microactuator is essential for making the electrostatic actuation more effective. In this paper, pull-in analysis is presented for an electrostatic torsion microactuator. The torsion microactuator can be used as a microtorsion mirror. A polynomial algebraic equation for the pull-in voltage and pull-in angle of a torsion microactuator is derived. Two types of microactuators fabricated using

Ofir Degani; Eran Socher; Ariel Lipson; T. Lejtner; Dan J. Setter; Shmuel Kaldor; Yael Nemirovsky

1998-01-01

229

Torsional (rotational) Vibration: Excitation of Small Rotating Machines  

NASA Astrophysics Data System (ADS)

The investigation of torsional vibration of rotating machines and rotational vibration of structural systems has been hindered by the lack of suitable transducers and torsional exciters. The advent of the laser torsional vibrometer has provided an accurate non-contact measurement technique for rotating machines. There is a requirement for further advancement in torsional excitation methods, particularly for low cost, low torque applications. In this paper, experimental results are presented which demonstrate that a commercially available a.c. servo-drive may be used as a combined drive motor and torsional exciter for small rotating test rigs. Two optimum servo-amplifier settings were identified and the maximum sinusoidal dynamic torque capacity running unloaded (below 1400 r.p.m.) was measured to be 1-10 Nm (r.m.s.), at frequencies up to at least 2 kHz. Random excitation was also possible at lower frequencies. The servo-drive will find applications in torsional vibration testing of small rotating machines and potentially for structural testing. The exciter has been characterized (i.e., the torsional stiffness and damping were measured) over the full speed range (2000 r.p.m.), so that the performance when attached to a particular test system may be predicted. Because previous researchers have demonstrated that inconsistent results may be obtained when experimentally measuring torsional damping levels, independent frequency and time domain techniques were used to determine the torsional stiffness and damping properties of the servo-drive, over a range of operating conditions of speed, load and torsional excitation level. A high degree of consistency was obtained between the results provided by using the different techniques under appropriate test conditions. The servo-drive was found to be a non-linear SDOF torsional system, with stiffness and damping levels dependent on motor speed, torsional excitation level and load inertia.

Drew, S. J.; Stone, B. J.

1997-04-01

230

A torsional parametric oscillator based on carbon nanotubes  

NASA Astrophysics Data System (ADS)

Parametric oscillations are observed in torsional electromechanical oscillators based on carbon nanotubes via molecular dynamics simulations. The stretch of nanotube torsion springs due to the vertical translational-electrostatic force acting on the paddle makes possible the parametric oscillations. The electrostatic force can provide control over nanotube stretching that allows it to parametrically modulate the torsional spring constant at twice the resonance frequency. This reveals potential building blocks for a variety of applications of the devices.

Jeong, Byeong-Woo; Sinnott, Susan B.

2009-08-01

231

Dynamic deformation and fracture behavior of ultrafine-grained aluminum alloy fabricates by equal-channel angular pressing  

NASA Astrophysics Data System (ADS)

In the present study, ultrafine-grained microstructures of a conventional 5083 aluminum alloy were fabricated by equal-channel angular pressing, and their dynamic deformation and fracture behavior were investigated. Dynamic torsional tests were conducted on four aluminum alloy specimens using a torsional Kolsky bar, and then the test data were analyzed in relation to microstructures, tensile properties, and adiabatic shear-banding behavior. The equal-channel angular-pressed (ECAP) specimens consisted of ultrafine grains and contained a considerable amount of second-phase particles, which were refined and distributed homogeneously in the matrix as the equal-channel angular pressing pass number increased. The dynamic torsional test results indicated that the maximum shear stress increased, while the fracture shear strain remained constant, with increasing equal-channel angular pressing pass number. Observation of the deformed area beneath the dynamically fractured surface showed that a number of voids initiated mainly at second-phase particle/matrix interfaces and that the number of voids increased with increasing pass number. Adiabatic shear bands of 200 to <300 µm in width were formed in the as-extruded and 1-pass ECAP specimens having coarser particles, whereas they were hardly formed in the four-pass and eight-pass ECAP specimens having finer particles. The possibility of adiabatic shear-band formation was explained by concepts of absorbed deformation energy and void initiation.

Kim, Yang Gon; Hwang, Byoungchul; Lee, Sunghak; Kim, Woo Gyeom; Shin, Dong Hyuk

2005-11-01

232

Torsion of Testis in an Infant with Unilateral UDT.  

PubMed

Torsion of an undescended testis is uncommon. Torsion of a cryptorchid testicle presents a nonspecific symptomatology. Clinical suspicion indicates emergent surgical exploration, irrespective of Doppler ultrasound with its inherent false negative results. Management of the contralateral testis is controversial. We emphasize the need of a complete physical examination of the child who goes to the emergency room with nonspecific symptoms of abdominal pain and ipsilateral empty hemiscrotum to rule out torsion of a cryptorchid testicle. Herein, we report a one-year-old infant with missed torsion of undescended left testis. PMID:21076534

Moslemi, Mohammad Kazem; Abedinzadeh, Mehdi; Al-Mousawi, Shabir

2010-01-01

233

Torsion of Testis in an Infant with Unilateral UDT  

PubMed Central

Torsion of an undescended testis is uncommon. Torsion of a cryptorchid testicle presents a nonspecific symptomatology. Clinical suspicion indicates emergent surgical exploration, irrespective of Doppler ultrasound with its inherent false negative results. Management of the contralateral testis is controversial. We emphasize the need of a complete physical examination of the child who goes to the emergency room with nonspecific symptoms of abdominal pain and ipsilateral empty hemiscrotum to rule out torsion of a cryptorchid testicle. Herein, we report a one-year-old infant with missed torsion of undescended left testis.

Moslemi, Mohammad Kazem; Abedinzadeh, Mehdi; Al-Mousawi, Shabir

2010-01-01

234

Torsional performance of turbine generator shafts especially under resonant excitation  

SciTech Connect

Interaction between the electrical transmission system and the turbine generator may induce torsional stresses to the shaft system whose magnitude and risk of damage have to be carefully analyzed in advance to ensure undisturbed operation and to preclude any damage from the unit. Within this task, the present paper investigates the torsional stressing which arise as a result of torsional resonance induced by pulsating components in the electrical torque of the generator and presents a method for assessing the susceptibility of natural torsional modes to excitation.

Lambrecht, D.; Kulig, T.

1982-10-01

235

Statistical prescission point model of fission fragment angular distributions  

NASA Astrophysics Data System (ADS)

In light of recent developments in fission studies such as slow saddle to scission motion and spin equilibration near the scission point, the theory of fission fragment angular distribution is examined and a new statistical prescission point model is developed. The conditional equilibrium of the collective angular bearing modes at the prescission point, which is guided mainly by their relaxation times and population probabilities, is taken into account in the present model. The present model gives a consistent description of the fragment angular and spin distributions for a wide variety of heavy and light ion induced fission reactions.

John, Bency; Kataria, S. K.

1998-03-01

236

Time-dependent photoelectron angular distributions  

NASA Astrophysics Data System (ADS)

I show that the angular distribution of electrons photoionized from gas phase targets by short light pulses is time-dependent, when the orbital momentum composition of the photocurrent changes with excitation energy so evolves with the time of detection. A theory of time- dependent photoionization is outlined and general formulas of time-dependent photoelectron flux and angular distribution are given. Two general propagator methods suitable to describe the time-dependent photoionization and scattering processes are developed. The photoionization process is viewed as a local excitation followed by a half scattering. The local excitation process is solved theoretically in a small region around the target core. This approach has been generalized to describe the evolution of a wavepacket in an unbound system. An asymptotic propagator theorem is discovered and used to derive analytic expressions for asymptotic propagators. The origin of the time dependence is explored by parameterizing the time delay and orbital momentum coupling in a two channel model. K-shell photoionization of N2 and CO are calculated with this time- dependent photoionization theory, implemented using a multiple scattering model. Numerical results demonstrate that the time dependence of photoelectron angular distributions is a realistic effect.

Wang, Xiangyang

1999-09-01

237

Measurement and analysis of angular velocity variations of twelve-cylinder diesel engine crankshaft  

NASA Astrophysics Data System (ADS)

This paper presents the procedures for measuring and analyzing the angular velocity variation of twelve-cylinder diesel engine crankshaft on its free end and on the power-output end. In addition, the paper deals with important aspects of the measurement of crankshaft torsional oscillations. The method is based on digital encoders placed at two distances, and one of them is a sensor not inserted directly on the shaft, i.e. a non-contact method with a toothed disc is used. The principle based on toothed disc is also used to measure the actual camshaft angular velocity of in-line compact high-pressure pump the engine is equipped with, and this paper aims to demonstrate the possibility of measuring the actual angular velocity of any rotating shaft in the engine, on which it is physically possible to mount a toothed disc. The method was created completely independently during long-range development and research tests of V46 family engines. This method is specific for its particular adaptability for use on larger engines with extensive vibrations and torsional oscillations. The main purpose of this paper is a practical contribution to all the more interesting research of the use of engine crankshaft angular velocity as a diagnostic tool for identifying the engine irregular running.

Bulatovi?, Ž. M.; Štavljanin, M. S.; Tomi?, M. V.; Kneževi?, D. M.; Bio?anin, S. Lj.

2011-11-01

238

Analysis of torsion-rotational transitions in the first three torsional states of CH 3OD  

NASA Astrophysics Data System (ADS)

In the framework of systematic analysis and fitting of transition frequencies of methanol isotopomers with a reduced torsion-rotational Hamiltonian that is obtained from the one-large-amplitude internal rotation model, 1126 Fourier transform far-infrared (FIR) transitions involving the second excited torsional level ( vt=2) have been added to the data set of Duan and McCoy [J. Mol. Spectros. 199 (2000) 302] to achieve a global fit of the observed high resolution microwave (MW), millimeter wave (MMW) and Fourier transform FIR spectra for CH 3OD. The CH 3OD data set contains 460 MW and MMW transitions and 3474 Fourier transform FIR transitions with vt?2 and J?21. The MW and MMW transitions have been fit with a root-mean-square (rms) deviation of 0.12 MHz, whereas FIR transitions have a rms deviation of 0.00026 cm -1. These deviations are approximately equal to the experimental uncertainties, indicating that the MW, MMW and FIR spectral transitions have been fit to an accuracy approaching the experimental uncertainties and the reduced torsion-rotational Hamiltonian model is capable of accurately describing CH 3OD energy levels up through the second excited torsional level. The success of the fit demonstrates that the increased general asymmetry in CH 3OD can be taken care adequately by the reduced Hamiltonian model.

Mukhopadhyay, Indranath; Duan, Yun-Bo

2000-07-01

239

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

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

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

2009-01-01

240

Angular Velocimeter for Aerospace Applications.  

National Technical Information Service (NTIS)

Low-level broad-band angular vibration measurement applications are continually developing. This has generated a pressing need for a low-level angular vibration sensor capable of measuring 0.000001 radians at frequencies from 0 to 10kHz, with a total size...

P. W. Whaley

1983-01-01

241

Intrinsic Angular Momentum of Light.  

ERIC Educational Resources Information Center

Derives a familiar torque-angular momentum theorem for the electromagnetic field, and includes the intrinsic torques exerted by the fields on the polarized medium. This inclusion leads to the expressions for the intrinsic angular momentum carried by the radiation traveling through a charge-free medium. (Author/MA)

Santarelli, Vincent

1979-01-01

242

Construction and validation tests of a torsion test machine  

Microsoft Academic Search

Present work aimed at developing, testing and operating a computerized prototype machine for performing cold plastic torsion tests. The operation and project of this machine were carried out in the Laboratory of Metal Forming at UDESC, Joinville. The equipment consists of a horizontal torsion machine composed of an electric motor, a wheel, a horizontal shaft and a control and acquisition

José Divo Bressan; Ricardo Kirchhof Unfer

2006-01-01

243

Modal analysis techniques for torsional vibration of diesel crankshafts  

Microsoft Academic Search

Torsional vibration in diesel engines, creates a potentially dangerous condition in that there may be no visible or audible indication of its existence, but catastrophic shaft fatigue failure can result. Classical methodology for torsional vibration analysis is cumbersome to employ and provides limited useful information. A methodology is presented which allows a quick and complete analysis of vibratory stress in

P. J. Carrato; C. C. Fu

1986-01-01

244

Torsion of the greater omentum with inguinal hernia.  

PubMed

Torsion of the greater omentum is an uncommon cause of acute abdomen, often diagnosed only intraoperatively. We report a 30-year-old man with torsion of the greater omentum in association with inguinal hernia, diagnosed on CT scan and managed conservatively. PMID:14658542

Xavier, Saju; John, Priya

2003-01-01

245

The Effect of Temperature on a Torsional Pendulum.  

National Technical Information Service (NTIS)

Testing was performed on a torsional pendulum to determine the amount of error introduced by temperature variation in determining moments of inertia. The torsional pendulum used in this test showed 0.0365 percent error per degree F variation in temperatur...

M. E. Traylor

1973-01-01

246

A Patient Presenting with Concurrent Testis Torsion and Epididymal Leiomyoma  

PubMed Central

Leiomyomas are the second most common tumors of epididymis. Patients with leiomyomas are sometimes misdiagnosed with testicular tumors. A Case of a patient with a scrotal mass presenting with testicular torsion is reported. Concurrent occurrence of testicular torsion and epididymal leiomyoma is an extremely rare condition.

Arpali, E.; Tok, A.

2013-01-01

247

Two Cases of Omental Torsion Mimicking Acute Appendicitis  

PubMed Central

Acute appendicitis is often simulated by other entities like mesenteric adenitis, worm infestation, Meckel’s diverticulitis, urinary tract infection and rarely omental torsion. We report two cases, a 6 year old boy and an 11 year old girl, who presented with symptoms and signs of acute appendicitis but upon exploration turned out to be omental torsion.

Liaqat, Naeem; Dar, Sajid Hameed; Sandhu, Asif Iqbal; Nayyer, Sajid

2014-01-01

248

Diagnostic Efficacy of Sonography for Diagnosis of Ovarian Torsion  

PubMed Central

Objectives: Misdiagnosing ovarian torsion is now suggested as an important issue in clinical setting. The aim of this study was to determine the diagnostic accuracy of sonography for ovarian torsion. Methods : In this study 323 women with acute pelvic pain with highly suspected ovarian torsion signs and symptoms attending Imam Reza Medical Center in Kermanshah between 2011 through 2012 were included and underwent a transabdominal sonography (2-5 MHz probes). Then findings of sonography were compared with laparatomy. Results : The ultrasound correctly diagnosed 72.1% of ovarian torsion and missed 27.9% of them (false negatives). However, one free subject (0.4%) was misclassified as ovarian torsion (false positive). There was a strong correlation between sonography and laparatomy with a kappa value of 84.0%. The sensitivity and specificity of sonography were 72.1% and 99.6%, respectively. Sonography had a positive predictive value of 96.9%, a negative predictive value of 95.9%, and a total accuracy of 96.0% for detection of ovarian torsion. Conclusion: Sonography appears to be an excellent method to evaluate patients with suspected ovarian torsion. Abnormal blood flow detected by sonography is highly predictive of ovarian torsion and is therefore useful in the diagnosis of this phenomenon.

Rostamzadeh, Ayoob; Mirfendereski, Sam; Rezaie, Mohammad Jafar; Rezaei, Shohreh

2014-01-01

249

Reinterpretation of the non-linear sigma model with torsion  

SciTech Connect

It is shown that the bosonic non-linear sigma model with torsion may be reinterpreted as a non-linear sigma model formulated on an algebraically extended two-dimensional worldsheet. The torsion term arises naturally as a consequence of the extended geometry. The two models, while locally equivalent, have distinct global features.

Gegenberg, J.; Kelly, P.F.; Mann, R.B.; McArthur, R.; Vincent, D.

1988-12-01

250

Prenatal bilateral extravaginal testicular torsion—a case presentation  

Microsoft Academic Search

A newborn male presented at birth with findings consistent with bilateral testicular torsion. Preoperative ultrasound demonstrated no flow to either testicle, and he underwent surgery, during which bilateral extravaginal testicular torsion was confirmed. The right testicle was grossly necrotic and orchidectomy was performed, whereas the left testicle was indeterminate and underwent detorsion and orchidopexy. At 6-month follow-up, the left testicle

Mathew D. Sorensen; Amanda M. Striegl; Martin A. Koyle

2004-01-01

251

Equations of Finite Differences Applied to Torsional Oscillations of Crankshafts  

Microsoft Academic Search

From the viewpoint of torsional oscillations an internal combustion engine with a long crankshaft is generally considered to be equivalent to a uniform shaft carrying equidistant identical disks. It is here shown that advantage can be taken of the regularity of such a system to simplify the calculation of torsional oscillations. This is done by applying a mathematical method known

Maurice A. Biot

1940-01-01

252

Torsional oscillations of relativistic stars with dipole magnetic fields  

Microsoft Academic Search

We present the formalism and numerical results for torsional oscillations of relativistic stars endowed with a strong dipole magnetic field, assumed to be confined to the crust. In our approach, we focus on axisymmetric modes and neglect higher order couplings induced by the magnetic field. We do a systematic search of parameter space by computing torsional mode frequencies for various

H. Sotani; K. D. Kokkotas; N. Stergioulas

2007-01-01

253

Torsional Vibration Assessment Using Induction Machine Electromagnetic Torque Estimation  

Microsoft Academic Search

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

Shahin Hedayati Kia; Humberto Henao; GÉrard-AndrÉ Capolino

2010-01-01

254

Torsional Directed Walks, Entropic Elasticity, and DNA Twist Stiffness  

Microsoft Academic Search

DNA and other biopolymers differ from classical polymers because of their torsional stiffness. This property changes the statistical character of their conformations under tension from a classical random walk to a problem we call the ``torsional directed walk.'' Motivated by a recent experiment on single lambda-DNA molecules [Strick, T. R., Allemand, J.-F., Bensimon, D., Bensimon, A. & Croquette, V. (1996)

J. David Moroz; Philip Nelson

1997-01-01

255

Angular control of optical cavities in a radiation-pressure-dominated regime: the Enhanced LIGO case  

NASA Astrophysics Data System (ADS)

We describe the angular sensing and control of the 4 km detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO). The culmination of first generation LIGO detectors, Enhanced LIGO operated between 2009 and 2010 with about 40 kW of laser power in the arm cavities. In this regime, radiation pressure effects are significant and induce instabilities in the angular opto-mechanical transfer functions. Here we present and motivate the angular sensing and control (ASC) design in this extreme case and present the results of its implementation in Enhanced LIGO. Highlights of the ASC performance are: successful control of opto-mechanical torsional modes, relative mirror motions of 1x10^{-7} rad rms, and limited impact on in-band strain sensitivity.

Dooley, Katherine L.; Barsotti, Lisa; Adhikari, Rana X.; Evans, Matthew; Fricke, Tobin T.; Fritschel, Peter; Frolov, Valera; Kawabe, Keita; Smith-Lefebvre, Nicolás

2013-12-01

256

The Angular Gyrus  

PubMed Central

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.

2013-01-01

257

The torsional barrier for the HCCH group  

NASA Astrophysics Data System (ADS)

Ab initio calculations have been carried out to examine the torsional barrier for non-linear HCCH fragments. At the SCF level the most stable configuration is skew for all geometries studied, but this is not found when correlation is included. For acetylene bond lengths and ? HCC = 121.2 °, the Møller-Plesset (MP) perturbation method gives trans as the most stable structure and the resulting torsion potential agrees with that calculated from an analytic many-body-expansion (MBE) potential of Halonen, Child and Carter. When the CC bond length is increased to 1.34 Å (as in ethene) or 1.54 Å (as in ethane), the MP method is poorly convergent and unreliable. Variational (CI) calculations at 1.34 A give a minimum at the trans structure, but at 1.54 A and ? HCC = 110.9° a skew structure is slightly more stable than trans. The MBE potential is in poor agreement with these calculations at the longer bond lengths, and is probably in error.

Marks, A.; Murrell, J. N.; Pedley, J. B.

1987-02-01

258

Stem torsion in total hip replacement  

PubMed Central

Background and purpose The clinical results of THR may be improved by correct femoral torsion. We evaluated the stem position by postoperative CT examination in 60 patients. Methods 60 patients requiring total hip arthroplasty were prospectively enrolled in this study. Minimally invasive THR was performed (anterior approach) in a lateral decubitus position and each patient underwent a postoperative CT examination. The position of the stem was evaluated by an independent external institution. Results Stem torsion ranged from –19° retrotorsion to 33° antetorsion. Normal antetorsion (i.e 10–15° according to Tönnis) was present in 5 of 60 patients, so the prevalence of abnormal stem antetorsion was 92% (95% CI: 82–97). We found a stem antetorsion outside the range of 0–25° in 21 of 60 hips. Women had a higher mean stem antetorsion (8.0° (SD 11)) than men (1.5° (SD 10)). Interpretation Postoperative stem antetorsion shows a high variability and is gender-related. We suggest precise assessment of stem antetorsion intraoperatively by means of computer navigation, preparing the femur first. In abnormal stem antetorsion, the cup position can be adjusted using a combined anteversion concept; alternatively, modular femoral components or stems with retroverted or anteverted necks (“retrostem”) could be used.

2010-01-01

259

Angular probe based on using Fabry-Perot etalon and scanning technique.  

PubMed

A novel angular probe using the Fabry-Perot etalon and angular scanning technique is proposed for absolute angular displacement determinations in this paper. The measurement theory is first derived, a setup constructed to implement the angular probe is then introduced and analyzed, and the experimental results from the uses of the setup are finally presented. The setup analyses reveal that the probe is with high measurement resolution and sensitivity. The experimental results not only confirm the validity, stability, accuracy, and repeatability, but also show an application of the angular probe. PMID:20174008

Lin, Shyh-Tsong; Yeh, Sheng-Lih; Lin, Zhi-Feng

2010-02-01

260

Torsional ARC Effectively Expands the Visual Field in Hemianopia  

PubMed Central

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.

Satgunam, PremNandhini; Peli, Eli

2012-01-01

261

Dynamic deformation and fracture behavior of ultra-fine-grained pure copper fabricated by equal channel angular pressing  

Microsoft Academic Search

Dynamic deformation and fracture behavior of ultra-fine-grained pure copper fabricated by equal channel angular pressing (ECAP) was investigated. The 1-pass ECAP’ed specimen consisted of fine dislocation cell structures, which were changed to very fine, equiaxed subgrains of 300–400nm in size with increasing number of ECAP pass. The dynamic torsional test results indicated that maximum shear stress increased with increasing number

Yang Gon Kim; Byoungchul Hwang; Sunghak Lee; Chul Won Lee; Dong Hyuk Shin

2009-01-01

262

Digital Instrumentation for Angular Velocity and Acceleration  

Microsoft Academic Search

An instrument is described for the measurement of angular velocity and angular acceleration of a rotating shaft, based upon an optical angular transducer and an associated operational digital (pulse rate) system. The angular transducer produces a pulse rate directly proportional to the instantaneous angular velocity and this quantity and its rate of change are processed by the pulse rate system

Alan Dunworth

1969-01-01

263

Toward Improved Description of DNA Backbone: Revisiting Epsilon and Zeta Torsion Force Field Parameters  

PubMed Central

We present a refinement of the backbone torsion parameters ? and ? of the Cornell et al. AMBER force field for DNA simulations. The new parameters, denoted as ??OL1, were derived from quantum-mechanical calculations with inclusion of conformation-dependent solvation effects according to the recently reported methodology (J. Chem. Theory Comput. 2012, 7(9), 2886-2902). The performance of the refined parameters was analyzed by means of extended molecular dynamics (MD) simulations for several representative systems. The results showed that the ??OL1 refinement improves the backbone description of B-DNA double helices and G-DNA stem. In B-DNA simulations, we observed an average increase of the helical twist and narrowing of the major groove, thus achieving better agreement with X-ray and solution NMR data. The balance between populations of BI and BII backbone substates was shifted towards the BII state, in better agreement with ensemble-refined solution experimental results. Furthermore, the refined parameters decreased the backbone RMS deviations in B-DNA MD simulations. In the antiparallel guanine quadruplex (G-DNA) the ??OL1 modification improved the description of non-canonical ?/? backbone substates, which were shown to be coupled to the ?/? torsion potential. Thus, the refinement is suggested as a possible alternative to the current ?/? torsion potential, which may enable more accurate modeling of nucleic acids. However, long-term testing is recommended before its routine application in DNA simulations.

Zgarbova, Marie; Luque, F. Javier; Sponer, Jiri; Cheatham, Thomas E.; Otyepka, Michal; Jurecka, Petr

2013-01-01

264

Multistep-shaping control based on the static and dynamic behavior of nonlinear optical torsional micromirror  

NASA Astrophysics Data System (ADS)

Electrostatically driven torsional micromirrors are suitable for optical microelectromechanical systems due to their good dynamic response, low adhesion, and simple structure for large-scale-integrated applications. For these devices, how to eliminate the excessive residual vibration in order to achieve more accurate positioning and faster switching is an important research topic. Because of the known nonlinearity issues, traditional shaping techniques based on linear theories are not suitable for nonlinear torsional micromirrors. In addition, due to the difficulties in calculating energy dissipation, the existing nonlinear command shaping techniques using energy method have neglected the effect of damping. We analyze the static and dynamic behavior of the electrostatically actuated torsional micromirrors. Based on the response of these devices, a multistep-shaping control considering the damping effects and the nonlinearity is proposed. Compared to the conventional closed-loop control, the proposed multistep-shaping control is a feedforward approach which can yield a good enough performance without extra sensors and actuators. Simulation results show that, without changing the system structure, the preshaping input reduces the settling time from 4.3 to 0.97 ms, and the overshoot percentage of the mirror response is decreased from 33.2% to 0.2%.

Bai, Cheng; Huang, Jin

2014-05-01

265

Left Ventricular Torsion Changes Post Kidney Transplantation  

PubMed Central

Background To quantify changes of left ventricular (LV) torsion in patients' pre and post kidney transplantation. Methods A prospective study was conducted on 48 patients who received kidney transplantation for end stage renal disease and without myocardial infarction. The rotation, twist and torsion of LV were studied pre and post kidney transplantation (6 months post transplantation) using velocity vector imaging by echocardiography. The data is expressed as mean ± standard deviation and compared by paired t-test at the p < 0.05 significance level. Results Six months post kidney transplantation, left ventricular ejection fraction (from 40.33 ± 11.42 to 61.00 ± 13.68%), ratio of mitral early and late diastolic filling velocity (from 1.04 ± 0.57 to 1.21 ± 0.52), rotation of basal LV (from 4.48 ± 2.66 to 5.65 ± 2.64 degree), rotation of apical LV (from 4.27 ± 3.08 to 5.50 ± 4.25 degree), LV twist (8.75 ± 4.45 to 11.14 ± 5.25 degree) and torsion (from 1.06 ± 0.54 to 1.33 ± 0.61 degree/cm) were increased significantly (p < 0.05). Interventricular septum thickness (from 11.67 ± 2.39 to 9.67 ± 0.48 mm), left ventricular mass index (from 104.00 ± 16.47 to 95.50 ± 21.44 g/m2), systolic blood pressure (from 143.50 ± 34.99 to 121.50 ± 7.09 mmHg), serum blood urea nitrogen (from 42.40 ± 7.98 to 30.43 ± 13.85 mg/dL) and creatinine (from 4.53 ± 1.96 to 2.73 ± 2.57 mg/dL) were decreased significantly (p < 0.05). Conclusion Kidney transplantation in end stage renal disease without myocardial infarction results in improvement in left ventricular structure, function and myocardial mechanics as detected by echocardiography and velocity vector imaging. Velocity vector imaging provided valuable information for detection and follow-up of cardiac abnormalities in patients with end stage renal disease.

Deng, Yan; Pandit, Anil; Heilman, Raymond L.; Chakkera, Harini A.; Mazur, Marek J.

2013-01-01

266

The microstructure and texture of torsion-reverse torsion experiments. [Al-1Mg  

SciTech Connect

Recent experiments with short thin-walled tubes (Lindholm design) tested in torsion and reverse torsion have confirmed both the persistence of a shear texture at zero net strain and the restoration of the grain shape. Calculations of theoretical texture development using a code based on the Bishop and Hill analysis have confirmed the reversibility of texture development when Taylor-based models are used. This code includes the effect or Relaxed Constraints and uses a nonlinear strain rate sensitivity to resolve the ambiguity of slip system choice. Calculations performed with the Asaro-Needleman code do leave a small residual texture at zero net strain. The conclusion is that there is sometimes an irreversible component of texture development that is not accounted for by the geometry of plastic deformation. 11 refs., 6 figs.

Rollett, A.D.; Lowe, T.; Kocks, U.F.; Stout, M.G.

1987-01-01

267

Exact solutions for the flow of second grade fluid in annulus between torsionally oscillating cylinders  

NASA Astrophysics Data System (ADS)

The velocity field and the associated shear stress corresponding to the torsional oscillatory flow of a second grade fluid, between two infinite coaxial circular cylinders, are determined by means of the Laplace and Hankel transforms. At time t = 0, the fluid and both the cylinders are at rest and at t = 0+, cylinders suddenly begin to oscillate around their common axis in a simple harmonic way having angular frequencies ?1 and ?2. The obtained solutions satisfy the governing differential equation and all imposed initial and boundary conditions. The solutions for the motion between the cylinders, when one of them is at rest, can be obtained from our general solutions. Furthermore, the corresponding solutions for Newtonian fluid are also obtained as limiting cases of our general solutions.

Mahmood, Amir; Parveen, Saima; Khan, Najeeb Alam

2011-04-01

268

Identification of biomolecular conformations from incomplete torsion angle observations by hidden Markov models.  

PubMed

We present a novel method for the identification of the most important conformations of a biomolecular system from molecular dynamics or Metropolis Monte Carlo time series by means of Hidden Markov Models (HMMs). We show that identification is possible based on the observation sequences of some essential torsion or backbone angles. In particular, the method still provides good results even if the conformations do have a strong overlap in these angles. To apply HMMs to angular data, we use von Mises output distributions. The performance of the resulting method is illustrated by numerical tests and by application to a hybrid Monte Carlo time series of trialanine and to MD simulation results of a DNA-oligomer. PMID:17680553

Fischer, Alexander; Waldhausen, Sonja; Horenko, Illia; Meerbach, Eike; Schütte, Christof

2007-11-30

269

Chirality and angular momentum in optical radiation  

NASA Astrophysics Data System (ADS)

This paper develops, in precise quantum electrodynamic terms, photonic attributes of the “optical chirality density,” one of several measures long known to be conserved quantities for a vacuum electromagnetic field. The analysis lends insights into some recent interpretations of chiroptical experiments, in which this measure, and an associated chirality flux, have been treated as representing physically distinctive “superchiral” phenomena. In the fully quantized formalism the chirality density is promoted to operator status, whose exploration with reference to an arbitrary polarization basis reveals relationships to optical angular momentum and helicity operators. Analyzing multimode beams with complex wave-front structures, notably Laguerre-Gaussian modes, affords a deeper understanding of the interplay between optical chirality and optical angular momentum. By developing theory with due cognizance of the photonic character of light, it emerges that only the spin-angular momentum of light is engaged in such observations. Furthermore, it is shown that these prominent measures of the helicity of chiral electromagnetic radiation have a common basis in differences between the populations of optical modes associated with angular momenta of opposite sign. Using a calculation of the rate of circular dichroism as an example, with coherent states to model the electromagnetic field, it is discovered that two terms contribute to the differential effect. The primary contribution relates to the difference in left- and right-handed photon populations; the only other contribution, which displays a sinusoidal distance dependence corresponding to the claim of nodal enhancements, is connected with the quantum photon number-phase uncertainty relation. From the full analysis, it appears that the term “superchiral” can be considered redundant.

Coles, Matt M.; Andrews, David L.

2012-06-01

270

Doxorubicin, DNA torsion, and chromatin dynamics.  

PubMed

Doxorubicin is one of the most important anti-cancer chemotherapeutic drugs, being widely used for the treatment of solid tumors and acute leukemias. The action of doxorubicin and other anthracycline drugs has been intensively investigated during the last several decades, but the mechanisms that have been proposed for cell killing remain disparate and controversial. In this review, we examine the proposed models for doxorubicin action from the perspective of the chromatin landscape, which is altered in many types of cancer due to recurrent mutations in chromatin modifiers. We highlight recent evidence for effects of anthracyclines on DNA torsion and chromatin dynamics that may underlie basic mechanisms of doxorubicin-mediated cell death and suggest new therapeutic strategies for cancer treatment. PMID:24361676

Yang, Fan; Teves, Sheila S; Kemp, Christopher J; Henikoff, Steven

2014-01-01

271

Torsional ultrasonic transducer computational design optimization.  

PubMed

A torsional piezoelectric ultrasonic sensor design is proposed in this paper and computationally tested and optimized to measure shear stiffness properties of soft tissue. These are correlated with a number of pathologies like tumors, hepatic lesions and others. The reason is that, whereas compressibility is predominantly governed by the fluid phase of the tissue, the shear stiffness is dependent on the stroma micro-architecture, which is directly affected by those pathologies. However, diagnostic tools to quantify them are currently not well developed. The first contribution is a new typology of design adapted to quasifluids. A second contribution is the procedure for design optimization, for which an analytical estimate of the Robust Probability Of Detection, called RPOD, is presented for use as optimality criteria. The RPOD is formulated probabilistically to maximize the probability of detecting the least possible pathology while minimizing the effect of noise. The resulting optimal transducer has a resonance frequency of 28[kHz]. PMID:24882020

Melchor, J; Rus, G

2014-09-01

272

Suppression of common torsional mode interactions using shunt reactor controllers  

SciTech Connect

The paper presents the results of a study on the utilization of shunt reactors for the damping of common torsional mode interactions of a power system containing series-capacitor compensation. The IEEE Second Benchmark Model, system-2, which has two sets of nonidentical turbine-generators connected to an infinite bus via a common series--capacitor compensated transmission line, is employed to investigate the possible unstable Subsynchronous Resonance (SSR) modal interactions can be suppressed by using reactive power compensation. A set of shunt reactors are proposed and connected to the studied system and a unified approach based on modal control theory is employed to design shunt reactor controllers in order that all SSR modes in the system can be stabilized. For clearly demonstrating the effectiveness of the proposed scheme, SSR mode eigenvalues under different loading conditions and sensitivity analysis of shunt reactor controllers' parameters are performed. Dynamic responses of the nonlinear system simulation under a torque disturbance on generator shaft and a severe three-phase short-circuit fault at infinite bus are also carried out.

Li Wang; San Jan Mau; Chieh Chen Chuko (National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Electrical Engineering)

1993-09-01

273

Measurement of the orbital-angular-momentum spectrum of fields with partial angular coherence using double-angular-slit interference  

NASA Astrophysics Data System (ADS)

We implement an interferometric method using two angular slits to measure the orbital-angular-momentum (OAM) mode spectrum of a field with partial angular coherence. As the angular separation of the slits changes, an interference pattern for a particular OAM mode is obtained. The visibility of this interference pattern as a function of angular separation is equivalent to the angular correlation function of the field. By Fourier transforming the angular correlation function obtained from the double-angular-slit interference, we are able to calculate the OAM spectrum of the partially coherent field. This method has potential application for characterizing the OAM spectrum in high-dimensional quantum information protocols.

Malik, Mehul; Murugkar, Sangeeta; Leach, Jonathan; Boyd, Robert W.

2012-12-01

274

Significance of torsion modes in bowed-string dynamics  

NASA Astrophysics Data System (ADS)

Several aspects of bowed-string dynamics are still inadequately clarified. The importance of torsion modes on the motion regimes is one such issue. Experiments involving torsion are difficult and most of the results available pertain to numerical simulations. The authors' approach differs from previous efforts in two main aspects: (1) the development of a computational method distinct from the wave-propagation approach pioneered by McIntyre, Schumacher, and Woodhouse and (2) an extensive and systematic analysis of the coupling between torsion and transverse motions is performed. The numerical simulations are based on a modal representation of the unconstrained string and a computational approach for friction that enables accurate representations of the stick-slip forces and of the string dynamics, in both time and space. Many relevant aspects of the bowed-string can be readily implemented, including string inharmonic behavior, finite bow-width, and torsion effects. Concerning the later aspect, a realistic range of the torsional to transverse wave-speed ratio is investigated, for several values of the bow velocity and normal force. Results suggest that torsion modes can effect both transient durations and steady state regimes, in particular when the above-mentioned ratio is <4. Gut strings should then be particularly prone to torsion effects.

Inacio, Octavio; Antunes, Jose; Henrique, Luis

2002-11-01

275

Removal of Speckle Harmonics in Laser Torsional Vibrometry  

NASA Astrophysics Data System (ADS)

Torsional vibration measurements on rotating machinery have traditionally been undertaken using techniques such as mechanical torsiographs, strain gauging with slip rings or telemetry systems, and encoders (slotted disks, gears, etc.). These techniques have the common limitation that the test machine has to be stopped in order to attach the transducer. The application of a cross-beam laser vibrometer to torsional vibrometry by Simpson and Lamb [1] and further development by Halliwell et al.[2] provided a non-contact torsional measurement technique, resulting in significant time savins. However, this design was restricted to use on shafts with a circular cross-section and had a very small beam crossing zone (<1 mm in depth), which had to be focussed carefully on the shaft surface. This cross-beam design was also unable to distinguish between torsional and transverse shaft vibrations. The invention of the modern (parallel beam) laser torsional vibrometer (LTV) by researchers at the ISVR in Southampton [3,4] overcame the main limitations of the cross-beam device. Their elegant design responds inherently to torsional vibrations only and may be used with shafts of arbitrary cross-section. In addition, the laser probe may be hand-held and there is a significant tolerance in the allowable distance between the laser source and the target surface (typically between 5 and 45 cm). A recent review paper on the development and application of laser torsional vibrometers has been published by Halliwell [5].

Drew, S. J.; Stone, B. J.

1997-09-01

276

Angular encoding with Larmor precession  

NASA Astrophysics Data System (ADS)

The first test of angular encoding of a neutron beam with Larmor precession was performed at the spin-echo set-up of ZETA on IN3 (ILL, Grenoble, France). The polymer multilayer sample exhibits specular and off-specular scattering previously measured with reflectometry. The Yoneda scattering was discriminated from the specular reflection employing the angular encoding. The scans of the reflected and the off-specular scattered intensities as a function of the spin-echo length reveal its sinusoidal intensity dependence and the phase relation with respect to each other. The phase shift between the off-specular scattering and specular reflected intensity produced the wanted and necessary angular resolution. An estimation of the effective resolution abilities of this method in reflectometry kinematics yields that the angular encoding including subsequent deconvolution is useful for any divergent or convergent incoming or outgoing beam in order to separate signals.

Jernenkov, M.; Lauter, H.; Lauter-Pasyuk, V.; Toperverg, B.; Klimko, S.; Gähler, R.

2005-02-01

277

Experimental investigation of cyclic thermomechanical deformation in torsion  

NASA Technical Reports Server (NTRS)

An investigation of thermomechanical testing and deformation behavior of tubular specimens under torsional loading is described. Experimental issues concerning test accuracy and control specific to thermomechanical loadings under a torsional regime are discussed. A series of shear strain-controlled tests involving the nickel-base superalloy Hastelloy X were performed with various temperature excursions and compared to similar thermomechanical uniaxial tests. The concept and use of second invariants of the deviatoric stress and strain tensors as a means of comparing uniaxial and torsional specimens is also briefly presented and discussed in light of previous thermomechanical tests conducted under uniaxial conditions.

Ellis, John R.; Castelli, Michael G.; Bakis, Charles E.

1992-01-01

278

Isolated tubal torsion in pregnancy--a rare case.  

PubMed

Isolated fallopian tube torsion is an uncommon cause of acute abdomen in pregnancy. Patients present with lower quadrant abdominal pain, and some have nausea and vomiting. There is no pathognomic diagnostic sign, so most patients are operated when it is too late to save the tube by detorsion alone. Here we present a case of isolated tubal torsion in a term pregnancy managed by salpingectomy and cesarean section simultaneously. As far as we know this will be the 20th case of reported isolated tubal torsion in pregnancy. PMID:21995163

I?çi, H; Güdücü, N; Gönenç, G; Basgul, A Y

2011-01-01

279

Coupling and degenerating modes in longitudinal-torsional step horns.  

PubMed

Longitudinal-torsional vibration is used and proposed for a variety of ultrasonic applications including motors, welding, and rock-cutting. To obtain this behavior in an ultrasonic step horn one can either, (i) couple the longitudinal and torsional modes of the horn by incorporating a ring of diagonal slits in the thick base section or, (ii) place helical flutes in the thin stem section to degenerate the longitudinal mode into a modified behavior with a longitudinal-torsional motion. This paper compares the efficacy of these two design approaches using both numerical and experimental techniques. PMID:22770885

Harkness, Patrick; Lucas, Margaret; Cardoni, Andrea

2012-12-01

280

The torsion of box beams with one side lacking  

NASA Technical Reports Server (NTRS)

The torsion of box beams of rectangular section, the edges of which are strengthened by flanges, and of which one side is lacking, is analyzed by the energy method. The torsional stresses are generally taken up by the bending of the two parallel walls, the rigidity of which is augmented by the third wall. The result was checked experimentally on duralumin and plywood boxes. The torsion recorded was 10 to 30 percent less than that given by the calculation, owing to self-stiffening.

Cambilargiu, E

1940-01-01

281

Gastric dilatation-volvulus after splenic torsion in two dogs.  

PubMed

Two dogs developed gastric dilatation-volvulus 2 and 17 months, respectively, after splenectomy for treatment of splenic torsion. Splenic displacement and torsion may stretch the gastric ligaments, allowing increased mobility of the stomach. After splenectomy, an anatomic void may be created in the cranioventral part of the abdomen, contributing to the mobility of the stomach. Veterinarians treating dogs with isolated splenic torsion may wish to consider prophylactic gastropexy at splenectomy, to reduce the chance of future gastric dilatation-volvulus. Prophylactic gastropexy should be done only if the dog's hemodynamic status is stable enough to allow for performance of the additional surgery. PMID:7628930

Millis, D L; Nemzek, J; Riggs, C; Walshaw, R

1995-08-01

282

Torsion and noninertial effects on a nonrelativistic Dirac particle  

NASA Astrophysics Data System (ADS)

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.

Bakke, K.

2014-07-01

283

Gravitational geometric phase in the presence of torsion  

NASA Astrophysics Data System (ADS)

We investigate the relativistic and non-relativistic quantum dynamics of a neutral spin-1/2 particle subject to an external electromagnetic field in the presence of a cosmic dislocation. We analyze the explicit contribution of the torsion in the geometric phase acquired in the dynamics of this neutral spinorial particle. We discuss the influence of the torsion in the relativistic geometric phase. Using the Foldy-Wouthuysen approximation, the non-relativistic quantum dynamics is studied and the influence of the torsion on the Aharonov-Casher and He-McKellar-Wilkens effects are discussed.

Bakke, Knut; Furtado, Claudio; Nascimento, J. R.

2009-04-01

284

Discussion on massive gravitons and propagating torsion in arbitrary dimensions  

SciTech Connect

In this paper, we reassess a particular R{sup 2}-type gravity action in D dimensions, recently studied by Nakasone and Oda, now taking torsion effects into account. Considering that the vielbein and the spin connection carry independent propagating degrees of freedom, we conclude that ghosts and tachyons are absent only if torsion is nonpropagating, and we also conclude that there is no room for massive gravitons. To include these excitations, we understand how to enlarge Nakasone-Oda's model by means of explicit torsion terms in the action and we discuss the unitarity of the enlarged model for arbitrary dimensions.

Hernaski, C. A.; Vargas-Paredes, A. A.; Helayeel-Neto, J. A. [Centro Brasileiro de Pesquisas Fisicas, Rua Dr. Xavier Sigaud 150, Urca, Rio de Janeiro, CEP 22290-180 (Brazil)

2009-12-15

285

Diagnosis and Laparoscopic Approach to Gallbladder Torsion and Cholelithiasis  

PubMed Central

Torsion of the gallbladder is common in elderly women. Different causes have been proposed for this rare condition. The presence of a long mesentery and loss of visceral fat are the main causes for the development of torsion. Patients present with a sudden, acute pain in the right upper quadrant, suggesting cholecystitis. Different imaging methods have shown particular findings, but the diagnosis is still complex. Today, just a few cases have been reported in the literature. The treatment for this condition consists of surgical detorsion and cholecystectomy. Gall-bladder torsion is a very rare entity and should be suspected when these clinical findings are present.

Alvarez, Jorge Fernandez; Uzqueda, Gonzalo Vargas

2010-01-01

286

Nonlinear torsional vibration of a circular cylindrical piezoelectric rod with relatively large shear deformation.  

PubMed

We show that, in a circular cylindrical rod, torsional modes are coupling to extension when the shear deformation associated with the torsional modes is no longer infinitesimal. A set of a couple equations is derived with which the effect of extension on the torsional frequency is examined. The results are useful to the understanding and design of devices operating with torsional modes. PMID:17718339

Yang, Jiashi

2007-07-01

287

Rotation speed measurement for turbine governor: Torsion filtering by using Kalman filter  

SciTech Connect

The rotation speed of a turbogenerator is disturbed by its shaft torsion. Obtaining a filtered measure of this speed is a problem of a great practical importance for turbine governor. A solution to this problem is explained using Kalman`s theory. The principles of the design, simulations and tests on the Electricite de France Micro-Network laboratory are presented showing several improvements over the current filter. Moreover, the described solution could be used profitably in all applications where it is necessary to substantially reduce a signal at given frequencies without causing too great a phase shift in the pass-band.

Houry, M.P.; Bourles, H. [Electricite de France, Clamart (France). Direction des Etudes et Recherches] [Electricite de France, Clamart (France). Direction des Etudes et Recherches

1996-01-01

288

Full Angular Profile of the Coherent Polarization Opposition Effect  

NASA Technical Reports Server (NTRS)

We use the rigorous vector theory of weak photon localization for a semi-infinite medium composed of nonabsorbing Rayleigh scatterers to compute the full angular profile of the polarization opposition effect. The latter is caused by coherent backscattering of unpolarized incident light and accompanies the renowned backscattering intensity peak.

Mishchenko, Michael I.; Luck, Jean-Marc; Nieuwenhuizen, Theo M.

1999-01-01

289

Coherent control of angular momentum transfer in resonant two-photon light-matter interaction.  

PubMed

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. PMID:20481880

Malik, D A; Kimel, A V; Kirilyuk, A; Rasing, Th; van der Zande, W J

2010-04-01

290

Non-uniform warping including the effects of torsion and shear forces. Part II: Analytical and numerical applications  

Microsoft Academic Search

This two-part contribution presents a beam theory (BT) with a non-uniform warping (NUW) including the effects of torsion, and shear forces and valid for any homogeneous cross-section made of isotropic elastic material. In part I, the governing equations of the NUW-BT has been established and simplified-NUW-BT versions has been deduced, wherein the number of degrees of freedom is reduced. In

Rached El Fatmi

2007-01-01

291

Angular momentum evolution during star and planetary system formation  

NASA Astrophysics Data System (ADS)

We focused on analysing the role played by protoplanetary disks in the evolution of angular momentum during star formation. If all the angular momentum contained within collapsing pre-stellar cores was conserved during their formation, proto-stars would reach rotation rates exceeding their break-up velocities before they reached the main sequence (Bodenheimer 1995). In order to avoid this occuring, methods by which proto-stars can lose angular momentum must exist. Angular momentum can be transferred from star to disk via stellar magnetic field lines through a process called magnetic braking (Camenzind 1990; Königl 1991). Alternatively, the stellar angular momentum can be lost from the star-disk system entirely via stellar- or disk-winds (e.g. Pelletier & Pudritz 1992; Matt & Pudritz 2005). The proportion of lost stellar angular momentum retained within the protoplanetary disk is important to studies of planetary system formation. If the bulk motion within the disk remains Keplerian, any increase of angular momentum in the disk causes an outward migration of disk material and an expansion of the disk. Therefore, an increase in disk angular momentum may cause a reduction in the disk surface density, often used to indicate the disk's ability to form planets. We made use of multi-wavelength data available in the literature to directly calculate the stellar and disk angular momenta for two nearby regions of star formation. Namely, these were the densely populated and highly irradiated Orion Nebula Cluster (ONC) and the comparitively sparse Taurus-Auriga region. Due to the limited size of the ONC dataset, we produced an average surface density profile for the region. We modelled the stars as solid body rotators due to their fully convective nature (Krishnamurthi et al. 1997) and assumed the disks are flat and undergo Keplerian rotation about the same rotation axis as the star. We observed the older disks within each of the two star forming regions to be preferentially larger and less massive, consistent with viscous accretion theories and disk dispersal. However, when drawing comparisons between the two regions, the ONC sample appeared to have less massive disks than the Taurus-Auriga sample, even though the population of Taurus-Auriga is older. This may suggest an influence of the birth cloud environment on protoplanetary disk evolution. Finally, the older stars within the ONC were observed to harbour disks that contained more angular momentum than their younger counterparts whereas, in the Taurus-Auriga sample, the amount of angular momentum contained in the older and younger samples was consistent. We suggest that the missing disk angular momentum in the older Taurus-Auriga disks may be contained within yet-undetected planets.

Davies, Claire L.; Greaves, Jane S.

2014-01-01

292

[Torsion of Morgagni hydatid in children (author's transl)].  

PubMed

Among the different types of testicular appendixes the most frequent is that of Morgagni hydatid. Authors review 32 cases of torsion of Morgagni hydatid operated along 12 years in the Department of Pediatric Surgery. PMID:7271084

Eizaguirre, I; Martínez Ibáñez, V; Boix-Ochoa, J

1981-03-01

293

Triaxial and Torsional Shear Test Results for Sand.  

National Technical Information Service (NTIS)

This report presents the results of the laboratory tests conducted in triaxial and torsional apparatus. The purposes of this report are not only to support the calibration and verification of the bounding surface hypoplasticity model for granular soil but...

B. L. Kutter Y. R. Chen C. K. Shen

1994-01-01

294

Use of the Torsional Pendulum in Material Characterization.  

National Technical Information Service (NTIS)

The mechanical behavior of many materials can be readily characterized by use of the torsional pendulum. The data obtained, shear modulus and damping decrement, provide elastic and inelastic parameters, and are generally representative of a material's mec...

A. J. Quant

1974-01-01

295

Characterization of Thermosetting Epoxy Systems Using a Torsional Pendulum.  

National Technical Information Service (NTIS)

An automated torsional pendulum has been used to investigate epoxy systems with respect to the effects of cure, transitions, morphology and active environments (water vapor and organic liquid). The findings include: (1) the thermosetting process is charac...

J. K. Gillham C. A. Glandt C. A. McPherson

1977-01-01

296

Torsional Pendulum Study on Several Epoxy/Diamine Polymers.  

National Technical Information Service (NTIS)

The purpose of this study is to determine the thermomechanical properties by using the torsional pendulum on the following epoxies: diglycidyl ether of bisphenol A, resorcinol diglycidyl ether, and butanediol diglycidyl ether with the following diamines p...

G. F. Lee

1977-01-01

297

An Inexpensive Torsional Pendulum Apparatus for Rigidity Modulus Measurement.  

ERIC Educational Resources Information Center

Described is an easy to assemble, and inexpensive, torsional pendulum which gives an accuracy of measurement of the modulus of rigidity, G, comparable to the accuracy obtained with the more expensive commercially available student models. (Author/GA)

Tyagi, S.; Lord, A. E., Jr.

1979-01-01

298

Nonminimal torsion-matter coupling extension of f(T) gravity  

NASA Astrophysics Data System (ADS)

We construct an extension of f(T) gravity with the inclusion of a nonminimal torsion-matter coupling in the action. The resulting theory is a novel gravitational modification, since it is different from both f(T) gravity, as well as from the nonminimal curvature-matter-coupled theory. The cosmological application of this new theory proves to be very interesting. In particular, we obtain an effective dark energy sector whose equation-of-state parameter can be quintessence- or phantom-like, or exhibit the phantom-divide crossing, while for a large range of the model parameters the universe enters in a de Sitter, dark-energy-dominated, accelerating phase. Additionally, we can obtain early-time inflationary solutions too, and thus provide a unified description of the cosmological history.

Harko, Tiberiu; Lobo, Francisco S. N.; Otalora, G.; Saridakis, Emmanuel N.

2014-06-01

299

Flap-lag-torsion aeroelastic stability of a circulation control rotor in forward flight  

NASA Technical Reports Server (NTRS)

The aeroelastic stability of a circulation control rotor blade undergoing three degrees of motion (flap, lag, and torsion) is investigated in forward flight. Quasi-steady strip theory is used to evaluate the aerodynamics forces; and the airfoil characteristics are from data tables. The propulsive and the auxiliary power trims are calculated from vehicle and rotor equilibrium equations through the numerical integration of element forces in azimuth as well as in radial directions. The nonlinear time dependent periodic blade response is calculated using an iterative procedure based on Floquet theory. The periodic perturbation equations are solved for stability using Floquet transition matrix theory. The effects of several parameters on blade stability are examined, including advance ratio, collective pitch, thrust level, shaft tilt, structural stiffnesses variation, and propulsive and auxiliary power trims.

Chopra, Inderjit; Hong, Chang-Ho

1987-01-01

300

[Prelabour uterine torsion complicated by partial abruption and fetal death].  

PubMed

Uterine torsion is a rare obstetrical complication whose diagnosis remains challenging. We report a case of 180degrees dextrogyre torsion at 36(+5) weeks of gestation complicated by partial abruption and in utero fetal death. Emergency cesarean section was performed through an unintentional posterior hysterotomy. Literature reports a few similar cases. Vertical hysterotomy should be advised in this context avoiding incision on lateral sides associated with increased risk of vascular or ureteral injury. PMID:24411298

Agar, N; Canis, M; Accoceberry, M; Bourdel, N; Lafaye, A-L; Gallot, D

2014-06-01

301

Ovarian torsion in a premenarcheal girl: MRI findings  

Microsoft Academic Search

Adnexal torsion is an uncommon cause of severe lower abdominal pain in women and is often difficult to distinguish from other\\u000a acute abdominal conditions. However, adnexal torsion should be considered in premenarcheal girls admitted with acute abdominal\\u000a pain and evidence of an ovarian mass. Accurate and early radiological diagnosis is mandatory immediately after onset of clinical\\u000a symptoms in order to

F. Van Kerkhove; M. Cannie; K. Op de beeck; D. Timmerman; A. Pienaar; M. H. Smet; D. Bielen; D. Vanbeckevoort; S. Dymarkowski

2007-01-01

302

Propagating torsion in 3D gravity and dynamical mass generation  

Microsoft Academic Search

In this paper, fermions are minimally coupled to 3D gravity with dynamical torsion. A Kalb–Ramond field is also introduced and non-minimally coupled to the fermions in a gauge-invariant way. We show that a 1-loop mass generation mechanism takes place for both the 2-form gauge field and the torsion. As for the fermions, no mass is dynamically generated: at 1-loop, there

J. L. Boldo; J. A. Helayel-Neto; N. Panza

2002-01-01

303

Propagating torsion in 3D gravity and dynamical mass generation  

Microsoft Academic Search

In this paper, fermions are minimally coupled to 3D gravity with dynamical torsion. A Kalb-Ramond field is also introduced and non-minimally coupled to the fermions in a gauge-invariant way. We show that a 1-loop mass generation mechanism takes place for both the 2-form gauge field and the torsion. As for the fermions, no mass is dynamically generated: at 1-loop, there

J. L. Boldo; J. A. Helayël-Neto; N. Panza

2002-01-01

304

Salvage Splenopexy for Torsion of Wandering Spleen in a Child  

PubMed Central

The wandering spleen is a rare condition characterized by the absence or underdevelopment of one or all of the splenic suspensory ligaments that resulting in increased splenic mobility and rarely torsion. Preventing infarction is the aim of a prompt surgery by splenopexy. We report a case of salvage splenopexy in torsion of a wandering spleen in a three year old girl presented with severe abdominal pain for three days.

Goyal, Ram Babu; Prabhakar, Girish; Mathur, Praveen; Mala, Tariq Ahmed

2014-01-01

305

Salvage splenopexy for torsion of wandering spleen in a child.  

PubMed

The wandering spleen is a rare condition characterized by the absence or underdevelopment of one or all of the splenic suspensory ligaments that resulting in increased splenic mobility and rarely torsion. Preventing infarction is the aim of a prompt surgery by splenopexy. We report a case of salvage splenopexy in torsion of a wandering spleen in a three year old girl presented with severe abdominal pain for three days. PMID:24834385

Goyal, Ram Babu; Gupta, Rahul; Prabhakar, Girish; Mathur, Praveen; Mala, Tariq Ahmed

2014-01-01

306

Torsional rigidity of positively and negatively supercoiled DNA  

Microsoft Academic Search

Time-correlated single-photon counting of intercalated ethidium bromide was used to measure the torsion constants of positively supercoiled, relaxed, and negatively supercoiled pBR322 DNA, which range in superhelix density from +0.042 to -0.123. DNA behaves as coupled, nonlinear torsional pendulums under superhelical stress, and the anharmonic term in the Hamiltonian is approximately 15 percent for root-mean-square fluctuations in twist at room

P. R. Selvin; D. N. Cook; N. G. Pon; M. P. Klein; J. E. Hearst; W. R. Bauer

1992-01-01

307

G2-structures with torsion from half-integrable nilmanifolds  

NASA Astrophysics Data System (ADS)

The equations for a G2-structure with torsion on a product M7=N6×S1 are studied in relation to the induced SU(3)-structure on N6. All solutions are found in the case when the Lee-form of the G2-structure is non-zero and N6 is a six-dimensional nilmanifold with half-integrable SU(3)-structure. Special properties of the torsion of these solutions are discussed.

Chiossi, Simon G.; Swann, Andrew

2005-07-01

308

Impact of shaft torsionals in steam turbine control  

Microsoft Academic Search

Shaft torsional vibrations are discussed along with their effect on steam turbine-generator control following severe supply-network disturbances and the destabilization of shaft torsional modes through the action of high-speed electrohydraulic controllers. It is shown that shaft flexibility can exert a significant influence on steam turbine-generator response following a severe supply-system disturbance, particularly when the turbine has nonlinear valve stroking and

T. J. Hammons

1989-01-01

309

Prenatal bilateral extravaginal testicular torsion--a case presentation.  

PubMed

A newborn male presented at birth with findings consistent with bilateral testicular torsion. Preoperative ultrasound demonstrated no flow to either testicle, and he underwent surgery, during which bilateral extravaginal testicular torsion was confirmed. The right testicle was grossly necrotic and orchidectomy was performed, whereas the left testicle was indeterminate and underwent detorsion and orchidopexy. At 6-month follow-up, the left testicle remained within normal clinical limits with good flow on ultrasound examination. PMID:15459781

Sorensen, Mathew D; Galansky, Stanley H; Striegl, Amanda M; Koyle, Martin A

2004-12-01

310

Non-Abelian anomalies on a curved space with torsion  

SciTech Connect

Using path-integral methods and /zeta/-function regularization a nonperturbative derivation of non-Abelian-covariant and consistent anomalies on a curved space with torsion is given. All terms depending on torsion, that one has in the expression of the consistent anomaly, can be eliminated by adding suitable counterterms to the Lagrangian density. In this way, the well-known result of Bardeen is recovered. The so-called ''covariant anomaly'' will be discussed too.

Cognola, G.; Giacconi, P.

1989-05-15

311

Thermal conductivity and torsional oscillations of solid 4He  

NASA Astrophysics Data System (ADS)

Polycrystalline samples of hcp 4He of molar volume Vm = 19.5 cm3 with small amount of 3He impurities were grown in an annular container by the blocked-capillary method. Three concentrations of 3He, x3, were studied: isotopically purified 4He with the estimated x3 < 10-10, commercial `well-grade' helium with x3 ~ 3.10-7 and a mixture with x3 = 2.5.10-6. Torsional oscillations at two frequencies, 132.5 and 853.6 Hz, and thermal conductivity were investigated before and after annealing. The solid helium under investigation was located not only in the annular container but also in the axial fill line inside two torsion rods and dummy bob of the double-frequency torsional oscillator. The analysis of the frequency shifts upon loading with helium and changing temperatures of different parts of the oscillator suggests that the three techniques probe the properties of solid helium in three different locations: the two different torsion modes respond to the changes of the shear modulus of solid helium in either of the two torsion rods while the thermal conductivity probes the phonon mean free path in solid helium inside the annular container. The temperature and width of the torsional anomaly increase with increasing frequency and x3. The phonon mean free path increases with increasing x3. Annealing typically resulted in an increased phonon mean free path but often in little change in the torsional oscillator response. While the magnitude of the torsional anomaly and phonon mean free path can be very different in different samples, no correlation was found between them.

Brazhnikov, M. Yu.; Zmeev, D. E.; Golov, A. I.

2012-11-01

312

Torsional texturing of superconducting oxide composite articles  

DOEpatents

A method of texturing a multifilamentary article having filaments comprising a desired oxide superconductor or its precursors by torsionally deforming the article is provided. The texturing is induced by applying a torsional strain which is at least about 0.3 and preferably at least about 0.6 at the surface of the article, but less than the strain which would cause failure of the composite. High performance multifilamentary superconducting composite articles having a plurality of low aspect ratio, twisted filaments with substantially uniform twist pitches in the range of about 1.00 inch to 0.01 inch (25 to 0.25 mm), each comprising a textured desired superconducting oxide material, may be obtained using this texturing method. If tighter twist pitches are desired, the article may be heat treated or annealed and the strain repeated as many times as necessary to obtain the desired twist pitch. It is preferred that the total strain applied per step should be sufficient to provide a twist pitch tighter than 5 times the diameter of the article, and twist pitches in the range of 1 to 5 times the diameter of the article are most preferred. The process may be used to make a high performance multifilamentary superconducting article, having a plurality of twisted filaments, wherein the degree of texturing varies substantially in proportion to the radial distance from the center of the article cross-section, and is substantially radially homogeneous at any given cross-section of the article. Round wires and other low aspect ratio multifilamentary articles are preferred forms. The invention is not dependent on the melting characteristics of the desired superconducting oxide. Desired oxide superconductors or precursors with micaceous or semi-micaceous structures are preferred. When used in connection with desired superconducting oxides which melt irreversibly, it provides multifilamentary articles that exhibit high DC performance characteristics and AC performance markedly superior to any currently available for these materials. In a preferred embodiment, the desired superconducting oxide material is BSCCO 2223.

Christopherson, Craig John (Grafton, MA); Riley, Jr., Gilbert N. (Marlborough, MA); Scudiere, John (Bolton, MA)

2002-01-01

313

Angular pattern and binary angular pattern for shape retrieval.  

PubMed

In this paper, we propose two novel shape descriptors, angular pattern (AP) and binary angular pattern (BAP), and a multiscale integration of them for shape retrieval. Both AP and BAP are intrinsically invariant to scale and rotation. More importantly, being global shape descriptors, the proposed shape descriptors are computationally very efficient, while possessing similar discriminability as state-of-the-art local descriptors. As a result, the proposed approach is attractive for real world shape retrieval applications. The experiments on the widely used MPEG-7 and TARI-1000 data sets demonstrate the effectiveness of the proposed method in comparison with existing methods. PMID:24144665

Hu, Rong-Xiang; Jia, Wei; Ling, Haibin; Zhao, Yang; Gui, Jie

2014-03-01

314

Spectrally encoded angular light scattering.  

PubMed

The angular light scattering profile of microscopic particles significantly depends on their morphological parameters, such as size and shape. This dependency is widely used in state-of-the-art flow cytometry methods for particle classification. We introduce a new spectrally encoded angular light scattering method, with potential application in scanning flow cytometry. We show that a one-to-one wavelength-to-angle mapping enables the measurement of the angular dependence of scattered light from microscopic particles over a wide dynamic range. Improvement in dynamic range is obtained by equalizing the angular dependence of scattering via wavelength equalization. Continuous angular spectrum is obtained without mechanical scanning enabling single-shot measurement. Using this information, particle morphology can be determined with improved accuracy. We derive and experimentally verify an analytic wavelength-to-angle mapping model, facilitating rapid data processing. As a proof of concept, we demonstrate the method's capability of distinguishing differently sized polystyrene beads. The combination of this technique with time-stretch dispersive Fourier transform offers real-time and high-throughput (high frame rate) measurements and renders the method suitable for integration in standard flow cytometers. PMID:24514410

Adam, Jost; Mahjoubfar, Ata; Diebold, Eric D; Buckley, Brandon W; Jalali, Bahram

2013-11-18

315

Analysis of torsional oscillations using an artificial neural network  

SciTech Connect

In this paper, a novel approach using an artificial neural network (ANN) is proposed for the analysis of torsional oscillations in a power system. In the developed artificial neural network, those system variables such as generator loadings and capacitor compensation ratio which have major impacts on the damping characteristics of torsional oscillatio modes are employed as the inputs. The outputs of the neural net provide the desired eigenvalues for torsional modes. Once the connection weights of the neural network have been learned using a set of training data derived off-line, the neural network can be applied to torsional analysis in real-time situations. To demonstrate the effectiveness of the proposed neural net, torsional analysis is performed on the IEEE First Benchmark Model. It is concluded from the test results that accurate assessment of the torsional mode eigenvalues can be achieved by the neural network in a very efficient manner. Thereofore, the proposed neural network approach can serve as a valuable tool to system operators in conducting SSR analysis in operational planning.

Hsu, Y.Y.; Jeng, L,H. (Dept. of Electrical Engineering, National Taiwan Univ., Taipei (Taiwan, Province of China))

1992-12-01

316

Ovarian torsion in adolescent with chronic immune thrombocytopenia.  

PubMed

Ovarian torsions in adolescence are rarity, particularly bilateral, with mostly unknown etiology. Enlargement of the ovary contributes to torsion. Young girl presenting with abdominal pains, nausea and vomiting was for two days suspected and observed as gastroenteritis. By exclusion of gastroenteritis she was admitted for gynecological work-up. Ultrasound showed significantly enlarged right ovary, with tumor-like appearance. At the laparotomy, gynecologist found torsioned, necrotic ovary and ovariectomy was performed. Histology showed massive stromal bleeding (haemorrhage). Asymptomatic enlargement of remaining ovary occurred nine months after the ovariectomy. This enlargement was accompanied with platelets' fall and the possibility of repeated torsion impended. Thrombocytopenia was suspected from the first moment, but diagnosed after the surgery. Thrombocytopenia in adolescence requires additional attention as possible cause of intra-ovarian bleeding with consecutive enlargement and may lead to torsion. Oral contraceptives regulate dysfunctional bleeding, decrease ovarian volume and by so, may minimize risk of torsion. This strategy proved effective in the case we present. PMID:24851639

Sunj, Martina; Tandara, Marijan; Palada, Ivan; Cani?, Tomislav; Agni?, Ivan

2014-03-01

317

Theory, Theory  

NSDL National Science Digital Library

This lesson includes a theory-evaluation activity. A set of five scenarios (theories for how diverse life came into existence on Earth) is divided evenly throughout the class, so each student is asked to evaluate one theory. Students then come together in groups of five, so that all theories are represented in each group, where they are compared and evaluated. Each group reports to the entire class for further discussion and clarifications.

Kimmel, Michael

2007-12-12

318

Interferometric measurement of angular motion  

NASA Astrophysics Data System (ADS)

This paper describes the design and realization of a homodyne polarization interferometer for measuring angular motion. The optical layout incorporates carefully designed cat's eye retroreflectors that maximize the measurable range of angular motion and facilitate initial alignment. The retroreflectors are optimized and numerically characterized in terms of defocus and spherical aberrations using Zemax software for optical design. The linearity of the measurement is then calculated in terms of the aberrations. The actual physical interferometer is realized as a compact device with optical components from stock and without relying on adjustable holders. Evaluation of its performance using a commercial autocollimator confirmed a reproducibility within 0.1%, a non-linearity of less than 1 ppm with respect to the autocollimator, an upper limit to its sensitivity of about 5 × 10-11 rad/Hz from audioband down to 100 mHz and an angular measurement range of more than +/-1°.

Peña Arellano, Fabián Erasmo; Panjwani, Hasnain; Carbone, Ludovico; Speake, Clive C.

2013-04-01

319

Phenomenology of preequilibrium angular distributions  

SciTech Connect

The systematics of continuum angular distributions from a wide variety of light ion nuclear reactions have been studied. To first order, the shape of the angular distributions have been found to depend only on the energy of the outgoing particle and on the division of the cross section into multi-step direct and multi-step compound parts. The angular distributions can be described in terms of Legendre polynomials with the reduced polynomial coefficients exhibiting a simple dependence on the outgoing particle energy. Two integer and four continuous parameters with universal values are needed to describe the coefficients for outgoing energies of 2 to 60 MeV in all the reaction types studied. This parameterization combined with a modified Griffin model computer code permits the calculation of double differential cross sections for light ion continuum reactions where no data is available.

Kalbach, C.; Mann, F.M.

1980-05-01

320

Variations in atmospheric angular momentum  

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

321

Inheritance of idiopathic torsion dystonia among Jews.  

PubMed Central

Idiopathic torsion dystonia (ITD) has long been considered to be genetically determined, but the pattern of inheritance has been unclear. It has been suggested that inheritance may differ in Jews and non-Jews. In the present study, data gathered in a nationwide survey of ITD in Israel were analysed. Between 1969 and 1980, 47 patients were collected, of whom 40 were of European origin. In these European Jews, the ITD frequency was about 1:23 000 live births, which was five-fold greater than in Jews of Afro-Asian origin. Assuming that all cases fit the same genetic model, an X linked or a simple autosomal recessive model of inheritance did not agree well with our data. An autosomal dominant model with low penetrance could have accounted for our observations and would yield an ITD gene frequency in European Jews of 3 to 4:100 000. In view of the increased ages of their fathers, the isolated cases may have included some new mutations. Multifactorial inheritance was also possible. However, it may be inappropriate to assume that all cases have the same genetic basis, or even that all are inherited.

Zilber, N; Korczyn, A D; Kahana, E; Fried, K; Alter, M

1984-01-01

322

Control of Torsional Vibrations by Pendulum Masses  

NASA Technical Reports Server (NTRS)

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.

Stieglitz, Albert

1942-01-01

323

The external-anomeric torsional effect.  

PubMed

The rotational barrier for a methyl group at the end of an anomeric system is sometimes lower than we might have anticipated. Thus, in the trans-trans conformation of dimethoxymethane, the barrier to methyl rotation is calculated (B3LYP/6-311++G(2d,2p)) to be 2.22 kcal/mol, just slightly smaller than the corresponding barrier to rotation of the methyl group in methyl propyl ether of 2.32 kcal/mol. However, if the methyl being rotated in dimethoxymethane is placed into a gauche conformation, that rotational barrier is reduced to 1.52 kcal/mol. This substantial (0.80 kcal/mol relative to methyl propyl ether) reduction in barrier height in the latter case is attributed mainly to the change in the bond order of the C-O bond to which the methyl is attached, as a function of conformation, which in turn is a result of the anomeric effect. We have called this barrier lowering the external-anomeric torsional effect. This effect is apparently widespread in carbohydrates, and it results in the changing of conformational energies by up to about 2 kcal/mol. If polysaccharide potential surfaces are to be accurately mapped by molecular mechanics, this effect clearly needs to be accounted for. PMID:15780251

Lii, Jenn-Huei; Chen, Kuo-Hsiang; Johnson, Glenn P; French, Alfred D; Allinger, Norman L

2005-04-11

324

Rheology of synthetic polycrystalline halite in torsion  

NASA Astrophysics Data System (ADS)

Motivated by the need for halite rheology, we investigated the stress/strain/strain rate behaviour of halite to high shear strains in torsion, using polymer jackets whose strength does not influence halite rheology. The experimental results show that: (1) halite strength decays exponentially with temperature increase, being very weak at 300 °C (ca. 2 Nm); (2) power-laws fit the stress/strain rate data, from which we determined the stress exponent n between ca. 13 (60 °C) and ca. 3 (200 °C), indicating that n decreases exponentially with temperature increase; (3) the activation energy Q decreases exponentially with temperature increase, from ca. 159 kJ/mol (38 kcal/mol) at 60 °C to ca. 59 kJ/mol (14 kcal/mol) at 200 °C; (4) Q depends linearly on n with a slope of ca. 10. The empirical constitutive equation ??=12.1exp9.6+7.1E-6exp(1/T1.9E-4)? describes the experimental results. Comparison of the present and previous experimental results shows that halite is much weaker in shear than in axial compression or extension. This difference likely results from the rotational component of simple shear.

Marques, F. O.; Burg, J.-P.; Armann, M.; Martinho, E.

2013-01-01

325

Angular distribution of electrons emitted from Na clusters  

NASA Astrophysics Data System (ADS)

The angular distribution of photoelectron emission is explored from a theoretical perspective using time-dependent density-functional theory as a tool. We discuss the principal features of one- and two-photon processes for Na3+ with a simple jellium background. As more realistic test cases, we consider Na9+ and Na41+ with detailed ionic structure and compare the results with a jellium description. We find that high-frequency photons are required to resolve ionic details. Moreover, it is desirable to have simultaneously energy-resolved angular distributions to disentangle the details of the electronic structure.

Pohl, A.; Reinhard, P.-G.; Suraud, E.

2004-08-01

326

Angular distribution of electrons emitted from Na clusters  

SciTech Connect

The angular distribution of photoelectron emission is explored from a theoretical perspective using time-dependent density-functional theory as a tool. We discuss the principal features of one- and two-photon processes for Na{sub 3}{sup +} with a simple jellium background. As more realistic test cases, we consider Na{sub 9}{sup +} and Na{sub 41}{sup +} with detailed ionic structure and compare the results with a jellium description. We find that high-frequency photons are required to resolve ionic details. Moreover, it is desirable to have simultaneously energy-resolved angular distributions to disentangle the details of the electronic structure.

Pohl, A.; Reinhard, P.-G.; Suraud, E. [Institut fuer Theoretische Physik, Universitaet Erlangen, Staudtstrasse 7, D-91058 Erlangen (Germany); Laboratoire Physique Theorique, Universite P. Sabatier, 118 Route de Narbonne, F-31062 Toulouse cedex, France and Institut fuer Theoretische Physik, Universitaet Erlangen, Staudtstrasse 7, D-91058 Erlangen (Germany)

2004-08-01

327

NMR Determination of the Torsion Angle ? in ?-Helical Peptides and Proteins: The HCCN Dipolar Correlation Experiment  

NASA Astrophysics Data System (ADS)

Several existing methods permit measurement of the torsion angles ?, ? and ? in peptides and proteins with solid-state MAS NMR experiments. Currently, however, there is not an approach that is applicable to measurement of ? in the angular range -20° to -70°, commonly found in ?-helical structures. Accordingly, we have developed a HCCN dipolar correlation MAS experiment that is sensitive and accurate in this regime. An initial REDOR driven 13C'- 15N dipolar evolution period is followed by the C' to C ? polarization transfer and by Lee-Goldburg cross polarization recoupling of the 13C ?1H dipolar interaction. The difference between the effective 13C 1H and 13C 15N dipolar interaction strengths is balanced out by incrementing the 13C- 15N dipolar evolution period in steps that are a factor of R( R˜? CH/? CN) larger than the 13C- 1H steps. The resulting dephasing curves are sensitive to variations in ? in the angular region associated with ?-helical secondary structure. To demonstrate the validity of the technique, we apply it to N-formyl-[U- 13C, 15N] Met-Leu-Phe-OH (MLF). The value of ? extracted is consistent with the previous NMR measurements and close to that reported in diffraction studies for the methyl ester of MLF, N-formyl-[U- 13C, 15N]Met-Leu-Phe-OMe.

Ladizhansky, Vladimir; Veshtort, Mikhail; Griffin, Robert G.

2002-02-01

328

Non-Colinearity of Angular Velocity and Angular Momentum  

ERIC Educational Resources Information Center

Discusses the principles, construction, and operation of an apparatus which serves to demonstrate the non-colinearity of the angular velocity and momentum vectors as well as the inertial tensors. Applications of the apparatus to teaching of advanced undergraduate mechanics courses are recommended. (CC)

Burr, A. F.

1974-01-01

329

Measuring Angular Size and Distance  

NSDL National Science Digital Library

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.

330

Dispersion and phase shifts of torsional waves in forward models  

NASA Astrophysics Data System (ADS)

Torsional Alfvén waves have been thought to exist in the Earth's core since their theoretical prediction by Braginsky in 1970. More recently, they have been inferred from observations of secular variation and length of day, and also observed in geodynamo simulations. These inferences from geophysical data have provided an important means of estimating core properties such as viscosity and internal magnetic field strength. We produce 1D forward models of torsional waves in the Earth's core, also known as torsional oscillations, and study their evolution in a cylinder, a full sphere and an equatorially symmetric spherical shell. The key features of torsional waves in our models are: geometric dispersion, phase shifts and internal reflections. In all three core geometries, we find that travelling torsional waves undergo significant geometric dispersion that increases with successive reflections from the boundaries such that an initial wave pulse becomes unidentifiable within three transits of the core. This dispersion partly arises due to low amplitude wakes trailing behind sharply defined pulses during propagation, a phenomenon that is linked to the failure of Huygens' principle in the geometric setting of torsional waves. We investigate the relationship between geometric dispersion and wavelength, concluding that long wavelength features are more dispersive than short wavelength features. This result is particularly important because torsional waves inferred from secular variation are relatively long wavelength, and are therefore likely to undergo significant dispersion within the Earth's core. Torsional waves in all three geometries are reflected at the equator of the core-mantle boundary with the same sign as the incident wave, but display more complicated behaviour at the rotation axis. In a cylindrical core, the analytic solutions to the torsional wave equation are known. We use these to derive an expression for the phase shift that torsional waves undergo upon reflection at the equator of the core-mantle-boundary and when passing through the rotation axis. Finally, we identify a weak reflection at the tangent cylinder due to geometric effects in an equatorially symmetric shell, and observe other internal reflections due to strong magnetic field gradients.

Cox, G. A.; Livermore, P. W.; Mound, J. E.

2013-12-01

331

The effect of the torsional and stretching vibrations of C2H6 on the H+C2H6-->H2+C2H5 reaction  

NASA Astrophysics Data System (ADS)

We present a three-dimensional quantum scattering model to treat reactions of the type H+C2H6-->H2+C2H5. The model allows the torsional and the stretching degrees of freedom to be treated explicitly. Zero-point energies of the remaining modes are taken into account in electronic structure calculations. An analytical potential-energy surface was developed from a minimal number of ab initio geometry evaluations using the CCSD(T,full)/cc-pVTZ//MP2(full)/cc-pVTZ level of theory. The reaction is endothermic by 1.5 kcal mol-1 and exhibits a vibrationally adiabatic barrier of 12.0 kcal mol-1. The results show that the torsional mode influences reactivity when coupled with the vibrational C-H stretching mode. We also found that ethyl radical products are formed internally excited in the torsional mode.

Kerkeni, Boutheïna; Clary, David C.

2005-08-01

332

Angular control of optical cavities in a radiation-pressure-dominated regime: the Enhanced LIGO case.  

PubMed

We describe the angular sensing and control (ASC) of 4 km detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO). Enhanced LIGO, the culmination of the first generation LIGO detectors, operated between 2009 and 2010 with about 40 kW of laser power in the arm cavities. In this regime, radiation-pressure effects are significant and induce instabilities in the angular opto-mechanical transfer functions. Here we present and motivate the ASC design in this extreme case and present the results of its implementation in Enhanced LIGO. Highlights of the ASC performance are successful control of opto-mechanical torsional modes, relative mirror motions of ? 1×10(-7) rad rms, and limited impact on in-band strain sensitivity. PMID:24323024

Dooley, Katherine L; Barsotti, Lisa; Adhikari, Rana X; Evans, Matthew; Fricke, Tobin T; Fritschel, Peter; Frolov, Valera; Kawabe, Keita; Smith-Lefebvre, Nicolás

2013-12-01

333

Negative Energy And Angular Momentum Modes Of Thin Accretion Disks  

NASA Astrophysics Data System (ADS)

This work derives the linearized equations of motion, the Lagrangian density, the Hamiltonian density, and the canonical angular momentum density for general perturbations [? exp (im?) with m = 0, ± 1, ...] of a geometrically thin self-gravitating, homentropic fluid disk including the pressure. The theory is applied to “eccentric,” m = ± 1 perturbations of a geometrically thin Keplerian disk. We find m = 1 modes at low frequencies relative to the Keplerian frequency. Further, it is shown that these modes can have negative energy and negative angular momentum. The radial propagation of these low-frequency m = 1 modes can transport angular momentum away from the inner region of a disk and thus increase the rate of mass accretion. Depending on the radial boundary conditions there can be discrete low-frequency, negative-energy, m = 1 modes.

Zhang, L.; Lovelace, R. V. E.

2005-12-01

334

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

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

335

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

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

336

Electronic structures of boron nitride nanotubes subjected to tension, torsion, and flattening: A first-principles DFT study  

NASA Astrophysics Data System (ADS)

Electronic structures of (6,0), (8,0), and (10,0) single-walled boron nitride nanotubes (SWBNNTs) subjected to tension, torsion, and flattening are investigated using first-principles calculations. Energy bands and charge distributions of the SWBNNTs are calculated within the density-functional theory and forces required to deform the SWBNNTs are estimated using energy variation with deformation. Our calculations show that all the deformation modes decrease the energy gaps of the SWBNNTs because of a decrease in the conduction-band minimum (CBM) energy, which is caused by an overlap of CBM charge densities between circumferentially neighboring boron atoms. It is found that flattening with a force smaller than that applied for tension or torsion causes a larger decrease in energy gaps of the SWBNNTs and that the force required for flattening SWBNNTs is not unrealistic.

Kinoshita, Yusuke; Ohno, Nobutada

2010-08-01

337

Elevated temperature axial and torsional fatigue behavior of Haynes 188  

NASA Technical Reports Server (NTRS)

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.

Bonacuse, Peter J.; Kalluri, Sreeramesh

1995-01-01

338

Elevated temperature axial and torsional fatigue behavior of Haynes 188  

NASA Technical Reports Server (NTRS)

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.

Bonacuse, Peter J.; Kalluri, Sreeramesh

1992-01-01

339

Microelectromechanical Systems Resonator Utilizing Torsional-to-Transverse Vibration Conversion  

NASA Astrophysics Data System (ADS)

A silicon microelectromechanical systems (MEMS) resonator utilizing the torsional-to-transverse vibration conversion is designed, fabricated and evaluated. The resonant frequency for the torsional modes mostly depends on only beam length, providing a large tolerance in the fabrication process. It has been, however, a critical issue to investigate the mechanism for generating the torsional vibration and the reduction of motional resistance. We propose a new beam structure, in which four torsion beams are vibrated by twist force generated by a transverse beam. The novel process for fabricating resonators provides a narrow gap surrounded by flat surfaces, which can reduce the motional resistance. The fabricated resonators are measured with a laser-Doppler (LD) vibrometer. The scanning function of the LD vibrometer confirms the torsional-to-transverse vibration conversion has been successfully achieved. The measured resonant frequency, 10.96 MHz, is in good agreement with the simulated one. The Q-factor has been also measured to be as high as 2.2 × 104 in vacuum. The electrical characteristic is evaluated with an impedance analyzer. At the resonant frequency, the extracted motional resistance for the 0.5-?m-gap resonator is 2.0 M?, which is greatly reduced, owing to the narrow gap effect, from that of the 1-?m-gap resonator. The temperature coefficient of the resonant frequency between -40 and 85 °C, has been measured to be -24.4 ppm/deg. The resonant frequency linearly decreases as the temperature rises.

Kiso, Masaya; Okada, Mitsuhiro; Tamano, Akimasa; Fujiura, Hideaki; Miyauchi, Hideo; Niki, Kazuya; Tanigawa, Hiroshi; Suzuki, Kenichiro

2011-06-01

340

Fourier transform spectrum of the torsional band of hydrazine  

NASA Astrophysics Data System (ADS)

The far-infrared torsional band of hydrazine has been studied by Fourier transform spectroscopy with an apodized resolution of 0.011 cm -1. As a result of torsional as well as inversion tunneling, large splittings are observed in this b-type band. About 700 rRK and pPK transitions of 22 subbands with ? K· K? from -10 to +11 were assigned. The A- B, B- A, and E- E transitions were assigned for all subbands except for the ? K· K? = -2 and -1 subbands, for which only the nondegenerate transitions were observed. A global fitting, which includes all available ground state microwave data, was made using Hougen's group theoretical formalism. Several fitting constants, i.e., B- C, the trans torsional tunneling constant h3 vt, and the inversion tunneling constant h5 v, were found to exhibit large changes upon torsional excitation. The values of these constants in the torsional fundamental state are: B- C = 184.52(30) MHz, h3 vt = -912.0(21) MHz, and h5 v = 1994.1(16) MHz, where the numbers in parentheses are 1 ?.

Ohashi, Nobukimi; Lafferty, Walter J.; Olson, W. Bruce

1986-05-01

341

Prune belly syndrome, splenic torsion, and malrotation: a case report.  

PubMed

An 18 year old male with a history of prune belly syndrome (PBS) presented with acute abdominal pain and palpable left upper quadrant mass. Computed tomography (CT) of the abdomen revealed a medialized spleen with a "whirl sign" in the splenic vessels, consistent with splenic torsion. Coincidentally, the small bowel was also noted to be on the right side of the abdomen, while the colon was located on the left, indicative of malrotation. Emergent diagnostic laparoscopy confirmed splenic torsion and intestinal malrotation. Successful laparoscopic reduction of the splenic torsion was achieved, however, conversion to an open procedure by a vertical midline incision was necessary owing to the patient's unique anatomy. Open splenopexy with a mesh sling and Ladd's procedure were subsequently performed. Malrotation and wandering spleen are known, rare associated anomalies in PBS; however, both have not been reported concurrently in a patient with PBS in the literature. In patients with PBS, acute abdominal pain, and an abdominal mass, high clinical suspicion for gastrointestinal malformations and prompt attention can result in spleen preservation and appropriate malrotation management. We present a case of a teenager who presented with a history of PBS, acute abdominal pain, and a palpable abdominal mass. The patient was found to have splenic torsion and intestinal malrotation. The clinical findings, diagnostic imaging, and surgical treatment options of splenic torsion are reviewed. PMID:23414901

Tran, Sifrance; Grossman, Eric; Barsness, Katherine A

2013-02-01

342

Torsion of the Retroperitoneal Kidney: Uncommon or Underreported?  

PubMed Central

Vascular torsion in a renal allograft after placement in the retroperitoneum is rare and has only been reported twice in the literature. It is an extrinsically mediated process that occurs at the vascular pedicle resulting in graft compromise and potential loss. Rapid diagnosis and immediate surgical intervention may salvage allograft function. Herein, we present a unique case of a 42-year-old male that developed renal allograft torsion following a second kidney transplant placed in the retroperitoneum. Immediate detorsion did not resolve allograft dysfunction, and a biopsy revealed acute cellular mediated rejection. After antithymocyte globulin treatment, allograft function was salvaged. A review of the current literature shows that the incidence, morbidity, and long term allograft function of intraperitoneal and extraperitoneal torsion are different. As such, torsion of the retroperitoneal kidney demonstrates encouraging allograft salvage rates. Only the third case reported to date, this serves as a contribution to the growing body of literature in retroperitoneal renal torsion and reviews the risks, medication considerations, diagnostic tests, and treatment modalities in a unique disease process.

Sosin, Michael; Lumeh, Wuya; Cooper, Matthew

2014-01-01

343

The Angular Momentum of Baryons and Dark Matter Halos Revisited  

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

344

Controversy concerning the definition of quark and gluon angular momentum  

SciTech Connect

A major controversy has arisen in QCD as to how to split the total angular momentum into separate quark and gluon contributions, and as to whether the gluon angular momentum can itself be split, in a gauge-invariant way, into a spin and orbital part. Several authors have proposed various answers to these questions and offered a variety of different expressions for the relevant operators. I argue that none of these is acceptable and suggest that the canonical expression for the momentum and angular momentum operators is the correct and physically meaningful one. It is then an inescapable fact that the gluon angular momentum operator cannot, in general, be split in a gauge-invariant way into a spin and orbital part. However, the projection of the gluon spin onto its direction of motion, i.e. its helicity is gauge invariant and is measured in deep inelastic scattering on nucleons. The Ji sum rule, relating the quark angular momentum to generalized parton distributions, though not based on the canonical operators, is shown to be correct, if interpreted with due care. I also draw attention to several interesting aspects of QED and QCD, which, to the best of my knowledge, are not commented upon in the standard textbooks on field theory.

Leader, Elliot [Blackett laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom)

2011-05-01

345

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

NASA Technical Reports Server (NTRS)

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.

Hooper, Steven J.

1990-01-01

346

FREQUENCY FILTERING OF TORSIONAL ALFVEN WAVES BY CHROMOSPHERIC MAGNETIC FIELD  

SciTech Connect

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.

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

347

[Unilateral testicular torsion. Effect on the contralateral testis].  

PubMed

The unilateral testicular torsion produce alteration of contralateral testes, with a frequence of sterility and alteration sperm bigger than normal population. The great differences report for various authors in the works make necessary to know better the pathogenesis of the testicular torsion about the fertility. With the aim to study this aspect, we carry out this experimental work in that animals with testicular torsion, although with individual results very different, have, again the animals with sham intervention, less number of sperm (P less than 0.001), with less time of survivorship (P less than 0.001), bigger percentage of precocious agglutination and abnormal shape (P less than 0.001) and bigger quantity of immobile sperm. These alteration as adult animals, but they are bigger in the late. PMID:2485660

Sanjuán Rodríguez, S; Blesa Sánchez, E; Miró Arias, A; Molina Fernández, M; Barquero Fernández, A; Cardesa García, J J

1989-01-01

348

Modal analysis techniques for torsional vibration of diesel crankshafts  

SciTech Connect

Torsional vibration in diesel engines, creates a potentially dangerous condition in that there may be no visible or audible indication of its existence, but catastrophic shaft fatigue failure can result. Classical methodology for torsional vibration analysis is cumbersome to employ and provides limited useful information. A methodology is presented which allows a quick and complete analysis of vibratory stress in the circular portion of the shaft. The method, based on modal analysis techniques is adapted for use on a micro-computer. A stress history at all locations along the circular portion of the shaft is provided for all shaft natural modes due to total torsion input. Various parameters, including engine configuration, cylinder number, firing order, damping characteristics, and gas pressure characteristics are also investigated.

Carrato, P.J.; Fu, C.C.

1986-01-01

349

Fault diagnosis of planetary gearboxes via torsional vibration signal analysis  

NASA Astrophysics Data System (ADS)

Torsional vibration signals are theoretically free from the amplitude modulation effect caused by time variant vibration transfer paths due to the rotation of planet carrier and sun gear, and therefore their spectral structure are simpler than transverse vibration signals. Thus, it is potentially easy and effective to diagnose planetary gearbox faults via torsional vibration signal analysis. We give explicit equations to model torsional vibration signals, considering both distributed gear faults (like manufacturing or assembly errors) and local gear faults (like pitting, crack or breakage of one tooth), and derive the characteristics of both the traditional Fourier spectrum and the proposed demodulated spectra of amplitude envelope and instantaneous frequency. These derivations are not only effective to diagnose single gear fault of planetary gearboxes, but can also be generalized to detect and locate multiple gear faults. We validate experimentally the signal models, as well as the Fourier spectral analysis and demodulation analysis methods.

Feng, Zhipeng; Zuo, Ming J.

2013-04-01

350

Torsion Fatigue Testing of Polycrystalline Silicon Cross-Microbridge Structures  

NASA Astrophysics Data System (ADS)

In the rapid advancement of micro/nano-electro-mechanical systems (MEMS/NEMS) technology, however, the reliable applications lie in the characterization of the mechanical fatigue properties of the micro/nano-structures. This paper presents the fatigue life of polycrystalline silicon (poly-Si) cross-microbridge in torsion. The torsion testing specimens are fabricated by surface and bulk micromachining. In addition, the stresses of cross-microbridge structures are investigated at various dimensions. The numerical tool ANSYS is applied to calculate the stress distribution of the testing structure. The experimental fatigue life lies between 7.78× 104--1.48× 107 cycles in use of the MTS Tytron 250 microforce testing system. The collective plot of poly-Si fatigue including the results of torsion will provide the MEMS device designer and researcher a good reference in the future applications.

Hung, Jeng-Nan; Hocheng, Hong; Sato, Kazuo

2011-06-01

351

Unilateral testicular seminoma with simultaneous contralateral torsion: a case report  

PubMed Central

Introduction Testicular germ cell tumors are the most common malignancies in men. Testicular torsion is also a scrotal phenomenon seen in adolescence and adulthood. The co-occurrence of these two scrotal disorders is extremely rare. Case presentation A 28-year-old East Asian man presented at our hospital with painless bilateral scrotal swelling. Both scrotal ultrasonography and computed tomography findings showed bilateral testicular tumors, and magnetic resonance imaging demonstrated a lack of enhancement in his right testis, indicating a hemorrhagic infarction and a left testicular tumor. After a bilateral orchiectomy, the intraoperative and histopathological findings revealed a left seminoma with a complicating contralateral testicular torsion that had developed with hemorrhagic infarction. Conclusion Testicular germ cell tumor with contralateral torsion is extremely rare. We could differentiate this case from bilateral testicular tumors appropriately using magnetic resonance imaging, and suggest that magnetic resonance imaging examination may be necessary to diagnose bilateral testicular masses.

2012-01-01

352

Piezoelectric ultrasonic motor using longitudinal-torsional composite resonance vibration.  

PubMed

A piezoelectric ultrasonic motor, which uses longitudinal and torsional composite vibration, is examined in order to obtain high torque characteristics with small diameter. Piezoelectric ceramic elements, oscillating in both longitudinal and torsional modes, respectively, are used as piezoelectric stiffened modes having high electromechanical coupling factors k(33) and k(15), respectively. It is found that the resonant frequencies for longitudinal mode and torsional mode could coincide with each other in the ultrasonic motor, according to finite element method analysis and experimental measurement. The motor operating in both resonant vibrations indicated good performance. The 20-mm diameter motor exhibited 4 kgfcm maximum torque, 450 r/min maximum rotational speed, 40% maximum efficiency, and quick responsiveness, within 2.5 ms. PMID:18263235

Ohnishi, O; Myohga, O; Uchikawa, T; Tamegai, M; Inoue, T; Takahashi, S

1993-01-01

353

Graphene-based torsional resonator from molecular-dynamics simulation  

NASA Astrophysics Data System (ADS)

Molecular-dynamics simulations are performed to study graphene-based torsional mechanical resonators. The quality factor is calculated by QF=??/2?, where the frequency ? and lifetime ? are obtained from the correlation function of the normal mode coordinate. Our simulations reveal the radius dependence of the quality factor as QF=2628/(22R- 1+0.004R2), which yields a maximum value at some proper radius R. This maximum point is due to the strong boundary effect in the torsional resonator, as disclosed by the temperature distribution in the resonator. Resulting from the same boundary effect, the quality factor shows a power law temperature dependence with power factors below 1.0. The theoretical results supply some valuable information for the manipulation of the quality factor in future experimental devices based on the torsional mechanical resonator.

Jiang, Jin-Wu; Wang, Jian-Sheng

2011-12-01

354

Splenic Torsion Requiring Splenectomy Six Years Following Laparoscopic Nissen Fundoplication  

PubMed Central

Background: Laparoscopic Nissen fundoplication has become a mainstay in the surgical treatment of gastroesophageal reflux disease, as it has proved to be a durable, well-tolerated procedure. Despite the safety and efficacy associated with this procedure, surgeons performing this advanced laparoscopic surgery should be well versed in the potential intraoperative and postoperative complications. Methods: A case is presented of a rare complication of splenic torsion following laparoscopic Nissen fundoplication. Diagnostic evaluations and intraoperative findings are discussed. Results: We present an otherwise healthy 41-year-old woman who underwent a laparoscopic Nissen fundoplication 6 years earlier at another medical center and presented with worsening chronic left upper quadrant abdominal pain. She was diagnosed with torsion of the splenic vascular pedicle, resulting in heterogenicity of perfusion with associated hematoma requiring open splenectomy. Conclusion: Surgeons should be aware of splenic torsion as a potential, albeit rare, complication related to laparoscopic Nissen fundoplication.

Le, Khoi; Griner, Devan; Tackett, Darryl

2012-01-01

355

Phonons with orbital angular momentum  

SciTech Connect

Ion accoustic waves or phonon modes are studied with orbital angular momentum (OAM) in an unmagnetized collissionless uniform plasma, whose constituents are the Boltzmann electrons and inertial ions. For this purpose, we have employed the fluid equations to obtain a paraxial equation in terms of ion density perturbations and discussed its Gaussian beam and Laguerre-Gauss (LG) beam solutions. Furthermore, an approximate solution for the electrostatic potential problem is presented, allowing to express the components of the electric field in terms of LG potential perturbations. The energy flux due to phonons is also calculated and the corresponding OAM is derived. Numerically, it is shown that the parameters such as azimuthal angle, radial and angular mode numbers, and beam waist, strongly modify the profiles of the phonon LG potential. The present results should be helpful in understanding the phonon mode excitations produced by Brillouin backscattering of laser beams in a uniform plasma.

Ayub, M. K. [Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan); National Centre for Physics, Shahdra Valley Road, Quaid-i-Azam University Campus, Islamabad 44000 (Pakistan); Ali, S. [National Centre for Physics, Shahdra Valley Road, Quaid-i-Azam University Campus, Islamabad 44000 (Pakistan); Mendonca, J. T. [IPFN, Instituto Superior Tecnico, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal)

2011-10-15

356

Intensity Modeling of Methanol in the Torsional Manifold  

NASA Astrophysics Data System (ADS)

Methanol is a popular and very important molecule both in astrophysics and atmospheric science, for which reliable line intensities have long been desired by the user communities. Because of the low barrier to the large-amplitude torsional motion, the methanol spectrum is extremely rich and complicated, representing a significant challenge for global modeling. Not until recent years has the torsional manifold of v_t = 0, 1, and 2 levels been successfully globally modeled using a modified version of the BELGI code. The resulting global fit parameters were then used to predict line lists in the THz region, employing both permanent dipole moments and torsional dependence of the dipole moments from ab initio results for the intensity calculations. However, recent direct intensity measurements based on Fourier transform spectra from JPL call for improvement of the intensity model. Thus, we have initiated enhanced modeling of the measured intensities in the torsional manifold using an extended set of dipole moment parameters, including permanent (?_a, ?_b), torsionally dependent (?_{a3n?}, ?_{b3n?}, ?_{c3n?}), and K and J dependent terms. While we are hopeful that this will improve our intensity predictive power, we also foresee challenges in the modeling for the A torsional species since a substantial body of the measured A doublet transitions exhibit either small asymmetry splittings for low K and high J states or are barely to completely unresolved as K increases. The present status of this work is that the existing database still needs some cleaning up to make it consistent with the new code. We hope to report our early intensity fit results at the conference. Xu et. al., J. Mol. Spectrosc. {251} (2008) p305. Xu & Lovas, J. Phys. Chem. Ref. Data {26} (1997) p17. Mekhtiev et. al., J. Mol. Spectrosc. {194} (1999) p171. Brauer et. al., JQSRT {113} (2012) p128.

Xu, Li-Hong; Kleiner, Isabelle

2013-06-01

357

Response of Oversized Epoxy Strand Models to Axial, Torsional and Bending Loads.  

National Technical Information Service (NTIS)

Axial, torsional and bending loadings have been applied to the models. Strains, stresses and displacements have been determined using mechanical and electrical strain gages, dial gages and brittle coatings. In the case of axial and torsional loadings, the...

A. J. Durelli S. Machida

1972-01-01

358

Torsional Excitation and Interference Effects of Tall Buildings with Structural Eccentricity.  

National Technical Information Service (NTIS)

This report describes an experimental investigation in wind tunnel of torsional excitation of a tall square building with structural eccentricity and torsional interference effects on the eccentric building response from neighboring buildings of different...

W. J. Zhang K. C. S. Kwok Y. L. Xu

1992-01-01

359

Lung lobe torsion associated with chylothorax in a cat.  

PubMed

A 10.5-year-old domestic shorthair presented with a history of progressive inappetence, lethargy and elevated respiratory rate. Clinical and diagnostic findings confirmed the presence of a chylothorax with evidence of a mass or collapsed lung within the right cranial thorax. Computed tomography, sternotomy and histopathology confirmed the presence of a right middle lung lobe torsion associated with a chylothorax. The torsion was successfully managed with surgical removal of the affected lung lobe, and the patient continues to be asymptomatic 6 months postoperatively. PMID:21130674

Mclane, Megan J; Buote, Nicole J

2011-02-01

360

Torsion constraints in the Randall-Sundrum scenario  

NASA Astrophysics Data System (ADS)

Torsion appears due to fermions coupled to gravity and leads to the strongest particle physics bounds on flat extra dimensions. In this work, I consider torsion constraints in the case of a warped extra dimension with brane and bulk fermions. From current data I obtain a 3? bound on the TeV-brane mass scale ??>=2.2 (10) TeV for the anti-de Sitter curvature k=1(0.01) in (reduced) Planck units. If Dirac or light sterile neutrinos reside on the brane, the bound increases to 17 (78) TeV.

Lebedev, Oleg

2002-06-01

361

The Frequency of Torsional Vibration of a Tapered Beam  

NASA Technical Reports Server (NTRS)

A solution for the equation of torsional vibration of tapered beams has been found in terms of Bessel functions for beams satisfying the following conditions: (a) the cross sections along the span are similar in shape; and (b) the torsional stiffness of a section can be expressed as a power of a linear function of distance along the span. The method of applying the analysis to actual cases has been described. Charts are given from which numerical values can be immediately obtained for most cases of practical importance. The theoretical values of the frequency ratio have been experimentally checked on five beams having different amounts of taper.

Coleman, Robert

1939-01-01

362

Squeeze film damping effect on a MEMS torsion mirror  

NASA Astrophysics Data System (ADS)

In this paper we discuss the dynamical characteristics of a torsion mirror in microelectromechanical systems. The squeeze film is modeled using the so-called modified molecular gas film lubrication (MMGL) equation with the coupling effects of surface roughness and gas rarefaction. The MMGL equation is linearized and then a simple mapping method is utilized to obtain the analytical solution of the transformed two-dimensional diffusion equation. From the numerical analyses, it is shown that the surface roughness parameter (Peklenik number), the gas rarefaction parameter (inverse Knudsen number) and squeeze film damping frequencies significantly affect the dynamic characteristics (spring and damping coefficients) of the torsion mirror.

Chang, Kuo-Ming; Lee, Shun-Ching; Li, Shyh-Horng

2002-09-01

363

Calibrations, torsion classes, and wrapped M-branes  

SciTech Connect

The present work has two goals. The first is to complete the classification of geometries in terms of torsion classes of M-branes wrapping cycles of a Calabi-Yau manifold. The second goal is to give insight into the physical meaning of the torsion class constraints. We accomplish both tasks by defining new energy minimizing calibrations in M-brane backgrounds. When fluxes are turned on, it is these calibrations that are relevant, rather than those which had previously been defined in the context of purely geometric backgrounds.

Fayyazuddin, Ansar [Department of Natural Sciences, Baruch College, City University of New York, New York (United States); Husain, Tasneem Zehra [Jefferson Physical Laboratory, Harvard University, Cambridge, Massachusetts 02138 (United States)

2006-05-15

364

Coated Fused Silica Fibers for Enhanced Sensitivity Torsion Pendulum  

NASA Technical Reports Server (NTRS)

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.

Numata, Kenji; Horowitz, Jordan; Camp, Jordan

2007-01-01

365

Coated Fused Silica Fibers for Enhanced Sensitivity Torsion Pendulum  

NASA Astrophysics Data System (ADS)

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 thin metal film to obtain electrical conductivity. Our results indicate that it is possible to achieve a thermal noise limit lower by a factor of between 3 and 10, depending on the silica diameter, compared to the best tungsten fibers available. This will allow a corresponding increase in sensitivity of torsion pendulum used for weak force measurements, including the gravitational constant measurement and ground-based force noise testing for LISA mission.

Numata, Kenji

2006-12-01

366

Angular momentum drain - A mechanism for despinning asteroids  

NASA Technical Reports Server (NTRS)

The new mechanism of angular momentum drain is proposed to account for the relatively slow rotation rates of intermediate-sized asteroids. Impact ejecta on a spinning body preferentially escape in the direction of rotation, systematically draining away spin angular momentum and leading to the counterintuitive result that collisions can reduce the spin of midsized objects. The existing theory of asteroid rotation is reviewed, and the escape of ejecta from hypervelocity impacts on bodies of different sizes and physical properties is described. The effect of this mass loss on asteroidal rotation is calculated and shown to be a significant brake on the spins of intermediate-sized asteroids. Finally, this new process is incorporated in a revised theory of collisional evolution, its predictions are compared with observational data, and its applications are discussed.

Dobrovolskis, A. R.; Burns, J. A.

1984-01-01

367

Noncommutative geometry of angular momentum space U(su(2))  

Microsoft Academic Search

We study the standard angular momentum algebra [xi,xj]=ilambda?ijkxk as a noncommutative manifold Rlambda3. We show that there is a natural 4D differential calculus and obtain its cohomology and Hodge * operator. We solve the spin 0 wave equation and some aspects of the Maxwell or electromagnetic theory including solutions for a uniform electric current density, and we find a natural

Eliezer Batista; Shahn Majid

2003-01-01

368

Stepwise angular spectrum method for curved surface diffraction.  

PubMed

We present a method to calculate wave propagation between arbitrary curved surfaces using a staircase approximation approach. The entire curved surface is divided into multiple subregions and each curved subregion is approximated by a piecewise flat subplane allowing the application of conventional diffraction theory. In addition, in order to reflect the local curvature of each subregion, we apply the phase compensation technique. Analytical expressions are derived based on the angular spectrum method and numerical studies are conducted to validate our method. PMID:24921383

Hwang, Chi-Young; Oh, Seungtaik; Jeong, Il-Kwon; Kim, Hwi

2014-05-19

369

Double Auger decay in atoms: Probability and angular distribution  

Microsoft Academic Search

Within many-body perturbation theory (MBPT), the correlated decay of an inner-shell vacancy, namely, the double Auger effect, is considered. Expressions for the amplitude and probabilities are obtained in the lowest order of MBPT. The approximate formulas, in particular the ``shakeoff'' model, are discussed. The calculations are performed for the 1s-1-->2s-22p-1+q1+q2 transition in Ne. It is shown that the angular distribution

M. Ya. Amusia; I. S. Lee; V. A. Kilin

1992-01-01

370

Angular correlation patterns in double Auger decay  

Microsoft Academic Search

The angular distribution of two emitted electrons in the double Auger process in atoms has been theoretically investigated. In particular, the double Auger decay of a 1s vacancy in Ne and a 2p vacancy in Ar is considered. In analogy with double photoionization, we present a convenient parametrization of the angular correlation patterns for all possible angular momenta of the

A N Grum-Grzhimailo; N M Kabachnik

2004-01-01

371

Dynamic Finite Element Analysis of Extensional-Torsional Coupled Vibration in Nonuniform Composite Beams  

NASA Astrophysics Data System (ADS)

The application of a Dynamic Finite Element (DFE) technique to the extensional-torsional free vibration analysis of nonuniform composite beams, in the absence of flexural coupling, is presented. The proposed method is a fusion of the Galerkin weighted residual formulation and the Dynamic Stiffness Matrix (DSM) method, where the basis functions of approximation space are assumed to be the closed form solutions of the differential equations governing uncoupled extensional and torsional vibrations of the beam. The use of resulting dynamic trigonometric interpolation (shape) functions leads to a frequency dependent stiffness matrix, representing both mass and stiffness properties of the beam element. Assembly of the element matrices and the application of the boundary conditions then leads to a frequency dependent nonlinear eigenproblem, which is solved to evaluate the system natural frequencies and modes. Two illustrative examples of uniform and tapered cantilevered, Circumferentially Uniform Stiffness ( CUS), hollow, composite beams are presented. The influence of ply fibre-angle on the natural frequencies is also studied. The correctness of the theory and the superiority of the proposed DFE over the contrasting DSM and conventional FEM methods are confirmed by the published results and numerical checks. The discussion of results is followed by some concluding remarks.

Hashemi, Seyed M.; Roach, Andrew

2011-12-01

372

Influence of thermally induced chemorheological changes on the torsion of elastomeric circular cylinders  

NASA Astrophysics Data System (ADS)

When an elastomeric material is deformed and subjected to temperatures above some characteristic value T cr (near 100?C for natural rubber), its macromolecular structure undergoes time and temperature-dependent chemical changes. The process continues until the temperature decreases below T cr. Compared to the virgin material, the new material system has modified properties (reduced stiffness) and permanent set on removal of the applied load. A new constitutive theory is used to study the influence of the changes of macromolecular structure on the torsion of an initially homogenous elastomeric cylinder. The cylinder is held at its initial length and given a fixed twist while at a temperature below T cr. The twist is then held fixed and the temperature of the outer radial surface is increased above T cr for a period of time and then returned to its original value. Assuming radial heat conduction, each material element undergoes a different chemical change. After enough time has elapsed such that the temperature field is again uniform and at its initial value, the cylinder properties are now inhomogeneous. Expressions for the time variation of the twisting moment and axial force are determined, and related to assumptions about material properties. Assuming the elastomeric networks to act as Mooney-Rivlin materials, expressions are developed for the permanent twist on release of torque, residual stress, and the new torsional stiffness in terms of the kinetics of the chemical changes.

Wineman, Alan; Shaw, John

2006-05-01

373

Tension/torsion loading of composite laminates with free-edge boundary conditions  

NASA Technical Reports Server (NTRS)

A finite element analysis of a family of quasi-isotropic graphite/epoxy laminates was conducted for tension, torsion, and combined tension/torsion loading. The model was employed to investigate the effects of delaminations on torsional stiffness and also to evaluate the total strain energy release rates associated with these delaminations.

Hooper, Steven J.; Hagemeier, Rick; Ramaprasad, Srinivasan

1991-01-01

374

Effect of unilateral testicular torsion on blood flow and histology of contralateral testes  

Microsoft Academic Search

Background\\/Purpose: Infertility occurs in 25% of patients after unilateral testicular torsion; hence, the authors examined hemodynamic and histological changes in both testes after acute testicular torsion in neonatal piglets.Methods: The animals were anesthetized, intubated, ventilated, catheterized, and assigned randomly to a sham group or one of three experimental groups undergoing 720° torsion of the left testis for 8 hours after

Linh Nguyen; Gonzalo Lievano; Luna Ghosh; Jayant Radhakrishnan; Linda Fornell; Eunice John

1999-01-01

375

Using torsional vibration analysis as a synergistic method for crack detection in rotating equipment  

Microsoft Academic Search

A non-intrusive torsional vibration method for monitoring and tracking small changes in crack growth of reactor coolant pump shafts is presented in this paper. This method resolves and tracks characteristic changes in the natural torsional vibration frequencies that are associated with shaft crack propagation. The focus of this effort is to develop and apply the torsional vibration shaft cracking monitoring

Mitchell S. Lebold; K. Maynard; K. Reichard; M. Trethewey; D. Bieryla; Clifford Lissenden; David Dobbins

2004-01-01

376

Conservative management of bilateral asynchronous adnexal torsion with necrosis in a prepubescent girl  

Microsoft Academic Search

Conservative management of ovarian torsion consisting of detorsion and surgical stabilization of the involved ovary, and possibly including the uninvolved ovary, has been described in the adult population. A 6-year-old girl with a history of prior ovarian torsion resulting in oophorectomy presented with 72 hours of intermittent abdominal pain, anorexia, and 1 episode of vomiting. The patient had torsion of

Kristen Eckler; Marc R Laufer; Sally E Perlman

2000-01-01

377

Effect of Torsion and Warping on the Free Vibration of Sandwich Beams  

Microsoft Academic Search

The problem on free vibrations of wide sandwich beams is tackled in this paper. Torsional and warping effects in addition to flexure are included in the formulation of the dynamic problem. In order to show the effects of bending-torsion coupling and warping on the natural frequencies and the corresponding vibration modes, three cases are considered. First, the warping and torsion

K. S. Numayr; H. A. Qablan

2005-01-01

378

Novel comparative torsional analytical technique to predict mechanical reliability of emerging memory cards and packages  

Microsoft Academic Search

Torsional test is a method widely used to determine the behaviour of materials when subjected to torsional force. Packaged devices ranging from memory modules to cards are subjected to this test to predict its mechanical lifetime reliability. It is however, a challenge to predict an optimum torsion testing condition for new emerging packaged devices, with different package configurations. This paper

Jason Wong; Hu Guo Jun; Leow Chiap Yong; Spencer Chew

2006-01-01

379

Theoretical Analysis of the Torsion-Induced Optical Effect in a Plastic Optical Fiber  

Microsoft Academic Search

We have analyzed the optical effects induced by a torsion stress in a plastic optical fiber (POF). As a result of the torsion, the POF becomes biaxial and inhomogeneous. The new principal axes of the optical indicatrix and the new indices of refraction referred to them depend on the torsion strength, on the fiber transverse coordinates, and on the difference

J. Zubia; J. Arrue; A. Mendioroz

1997-01-01

380

APPLICATION OF WAVELET PACKET ANALYSIS FOR FAULT DETECTION IN ELECTROMECHANICAL SYSTEMS BASED ON TORSIONAL VIBRATION MEASUREMENT  

Microsoft Academic Search

This paper primarily focuses on detecting electrical faults in turbine generator sets by monitoring torsional vibrations with the help of the non-contact measurement technique and analysing the data acquired from torsional vibration meter. Torsional vibrations in shaft trains can be excited by periodic excitation due to a variety of electromagnetic disturbances or unsteady flow in large steam turbine generator sets

X. Li; L. Qu; G. Wen; C. Li

2003-01-01

381

Theory of Bodily Tides.  

National Technical Information Service (NTIS)

Different theories of bodily tides assume different forms of dependence of the angular lag (delta) upon the tidal frequency X (chi). In the old theory (Gerstenkorn 1955, MacDonald 1964, Kaula 1964) the geometric lag angle is assumed constant, while the ne...

M. Efroimsky V. Lainey

2007-01-01

382

Practical formula for the radiated angular momentum  

NASA Astrophysics Data System (ADS)

We present a simple formula for the radiated angular momentum based on a spin-weighted spherical harmonic decomposition of the Weyl scalar ?4 representing outgoing radiation in the Kinnersley tetrad. We test our formula by measuring the radiated angular momentum from three simulations of nonspinning equal-mass black-hole binaries with orbital angular momentum aligned along the x, y, and z axes, respectively. We find that the radiated angular momentum agrees with the differences in the remnant horizon spins and the initial angular momentum for each system.

Lousto, Carlos O.; Zlochower, Yosef

2007-08-01

383

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

NASA Astrophysics Data System (ADS)

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.

Mehrabi, Reza; Kadkhodaei, Mahmoud; Elahinia, Mohammad

2014-07-01

384

Torsion of the spleen with incomplete infarction: case report.  

PubMed

Torsion and infarction of a "wandering spleen" is a rare disease which is often confused with other acute abdominal crises. A correct preoperative diagnosis, when made, has usually been determined by arteriographic studies. A child is described in whom changes in the TcSC scan made a correct diagnosis possible by non-invasive methods. PMID:606747

Lernau, O Z; Baron, J; Nissan, S

1977-12-01

385

New Approaches to Data Acquisitions in a Torsion Pendulum Experiment  

ERIC Educational Resources Information Center

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.

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

2007-01-01

386

Nonlinear Modelling and Identification of Torsional Behaviour in Harmonic Drives  

Microsoft Academic Search

The demand for accurate and reliable positioning in industrial applications, especially in robotics and high-precision machines, has led to the increased use of Harmonic Drives. The unique performance features of harmonic drives, such as high reduction ratio and high torque capacity in a compact geometry, justify their widespread application. However, nonlinear torsional compliance and friction are the most fundamental problems

T. Tjahjowidodo; F. Al-Bender; H. Van Brussel

387

Mechanical properties of orthodontic wires in tension, bending, and torsion.  

PubMed

The mechanical properties of three sizes of stainless steel (SS), nickel-titanium (NT), and titanium-molybdenum (TM) orthodontic wires were studied in tension, bending, and torsion. The wires (0.016 inch, 0.017 by 0.025 inch, and 0.019 by 0.025 inch) were tested in the as-received condition. Tensile testing and stiffness testing machines along with a torsional instrument were used. Mean values and standard deviations of properties were computed. The data were analyzed statistically by analysis of variance using a factorial design. Means were ranked by a Tukey interval calculated at the 95 percent level of confidence. In tension, the stainless steel wires had the least maximum elastic strain or springback, whereas the titanium-molybdenum wires had the most. Higher values of springback indicate the capacity for an increased range of activation clinically. In bending and torsion, the stainless steel wires had the least stored energy at a fixed moment, whereas the nickel-titanium wires had the most. Spring rates in bending and torsion, however, were highest for stainless steel wires and lowest for nickel-titanium wires. A titanium-molybdenum teardrop closing loop delivered less than one half the force of a comparable stainless steel loop for similar activations. PMID:6961793

Drake, S R; Wayne, D M; Powers, J M; Asgar, K

1982-09-01

388

Experimental Unilateral Torsion of the Spermatic Cord in Guinea Pigs  

Microsoft Academic Search

A systematic investigation of the effects of unilateral torsion of the spermatic cord on the contralateral testis of the guinea pig was carried out for variable time peri- ods, ie, seven days, one, three and six months. Both histological and ultrastructural studies were made on all testicular autopsy materials collected from five groups of animals. Those five groups were: group

JYOTSNA CHAKRABORTY; JAGADISH JHUNJHUNWALA

389

Optical microshutters and torsional micromirrors for light modulator arrays  

Microsoft Academic Search

The fabrication and operation of surface micromachined light modulators are described. In particular, comb-driven polysilicon microshutters for interrupting a focused laser beam of 5 ?m in diameter are characterized. The shutters are suspended by novel compact meander springs, which favor their application in dense light modulator arrays. Torsional micromirrors working in a reflection mode, having two mirror states, were realized

V. P. Jaecklin; C. Linder; N. F. de Rooij; J.-M. Moret; R. Vuilleumier

1993-01-01

390

Prediction of Stress Relaxation for Compression and Torsion Springs.  

National Technical Information Service (NTIS)

An analytical technique was developed to predict the stress relaxation for compression and torsion springs. The technique uses uniaxial tensile-generated stress-relaxation data for spring wires. Based on the tension-induced stress-relaxation data, the tec...

D. J. Chang

1995-01-01

391

Torsion as Alternative to Curvature in the Description of Gravitation  

NASA Astrophysics Data System (ADS)

The general covariance principle, seen as an active version of the principle of equivalence, is used to study the gravitational coupling prescription in the presence of curvature and torsion. It is concluded that the coupling prescription determined by this principle is always equivalent with the corresponding prescription of general relativity. An application to the case of a Dirac spinor is made.

Carvalho de Andrade, Vanessa

2004-12-01

392

Nanoscopic liquid bridges exposed to a torsional strain  

NASA Astrophysics Data System (ADS)

In this paper we investigate the response to a torsional strain of a molecularly thin film of spherically symmetric molecules confined to a chemically heterogeneous slit pore by means of Monte Carlo simulations in the grand canonical ensemble. The slit pore comprises two identical plane-parallel solid substrates, the fluid-substrate interaction is purely repulsive except for elliptic regions attracting fluid molecules. Under favorable thermodynamic conditions the confined film consists of fluid bridges where the molecules are preferentially adsorbed by the attractive elliptic regions, and span the gap between the opposite substrate surfaces. By rotating the upper substrate while holding the lower one in position, bridge phases can be exposed to a torsional strain 0????/2 and the associated torsional stress T? of the (fluidic) bridge phases can be calculated from molecular expressions. The obtained stress curve T?(?) is qualitatively similar to the one characteristic of sheared confined films: as the torsion strain increases, T? rises to a maximum (yield point) and then decays monotonically to zero. By changing the ellipses’ aspect ratio while keeping their area constant, we also investigate the influence of the attractive elliptic patterns’ shape on T?(?).

Sacquin-Mora, Sophie; Fuchs, Alain H.; Schoen, Martin

2003-12-01

393

Angle of torsion of the femur and its correlates.  

PubMed

Unpaired femora (171), devoid of gross pathology and grouped by gender (94 male and 77 female) and side (88 left and 83 right), were used to measure the angle of femoral torsion and the maximum femur length and to score the degree of prominency of the superior cervical tubercle, intertrochanteric line, quadrate tubercle, linea aspera, and adductor tubercle. The angle of torsion ranged from -9 to +35 degrees with a mean of +12.3 degrees. The means were not significantly different either by gender or side. The angle correlated negatively with superior cervical tubercle, intertrochanteric line, and adductor tubercle (P < 0.001), positively with quadrate tubercle (P < 0.001) but not with linea aspera, neck-shaft angle, or length of femur. Bony prominences were significantly more apparent in males. There was no significant association between prominency and side. The torsion seems to be brought about by muscular activity and capsular and ligamentous strain at the hip. This study suggests to clinicians the possibility of correction of torsion defects in certain hip diseases of growing children by suitable alteration in posture of the lower extremity. PMID:8720785

Prasad, R; Vettivel, S; Isaac, B; Jeyaseelan, L; Chandi, G

1996-01-01

394

An Automated Method for Period Measurement of a Torsional Pendulum.  

National Technical Information Service (NTIS)

A pulse recognition circuit has been devised that enables it, when used in conjunction with a digital counter and printer, to determine the period of a torsional pendulum even though the amplitude of the pendulum is variable and exceeds 360 degrees. This ...

J. L. Stup

1966-01-01

395

Experimental Measurement of Single-Wall Carbon Nanotube Torsional Properties  

PubMed Central

We report on the characterization of nanometer-scale torsional devices based on individual single-walled carbon nanotubes as the spring elements. The axial shear moduli of the nanotubes are obtained through modeling of device reaction to various amounts of applied electrostatic force and are compared to theoretical values.

Hall, A. R.; An, L.; Liu, J.; Vicci, L.; Falvo, M. R.; Superfine, R.; Washburn, S.

2012-01-01

396

Pediatric ovarian torsion: case series and review of the literature  

PubMed Central

Background Ovarian torsion in children is an uncommon cause of acute abdominal pain but mandates early surgical management to prevent further adnexal damage. The clinical presentation mimics other pathologies, such as appendicitis. We sought to more completely characterize ovarian torsion with respect to pain and ancillary studies, such as urinalysis. Methods We performed a retrospective review of hospital charts of all patients aged 0–18 years with a diagnosis of ovarian torsion at the Children’s Hospital at London Health Sciences Centre, in London, Ont., from 1993 to 2008. Results We analyzed 13 charts of patients aged 7 months to 18 years. Most patients presented with peripheral leukocytosis, vomiting and right lower quadrant pain that did not radiate or migrate. On urinalysis, about half the patients demonstrated pyuria without bacteruria. Pelvic ultrasound revealed an ovarian cyst on the same side of the pain in 11 of 13 patients. Most were found to have a hemorrhagic cyst or ovary and underwent salpingo-oophorectomy or cystectomy within 48 hours of presentation. Conclusion Ovarian torsion should be considered in any female child with acute onset lower abdominal pain accompanied by vomiting. Pain can be characterized as constant or colicky, but unlike with appendicitis, does not typically migrate. Sterile pyuria is found in a substantial proportion of cases. Ultrasound is the most useful initial diagnostic modality, but the absence of flow on Doppler imaging is not always present. Conservative management with detorsion and oophoropexy is recommended.

Poonai, Naveen; Poonai, Caroline; Lim, Rodrick; Lynch, Tim

2013-01-01

397

Torsional Oscillations and Waves Projected on the Wall  

ERIC Educational Resources Information Center

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…

Bartlett, Albert A.

2008-01-01

398

Torsion Points on the Fermat Curves and Their Jacobians.  

National Technical Information Service (NTIS)

Let p be a prime greater than 3 and not equal to 7, and let K be the cyclotomic field obtained by adjoining a primitive p-th root of 1 to the rational numbers. We compute the image of the K-rational torsion part of the Mordell-Weil group of the Jacobian o...

P. Tzermias

1996-01-01

399

Optical MEMS devices based on micromachined torsion structure  

NASA Astrophysics Data System (ADS)

Optical MEMS components with optical fiber inputs and outputs are the most important kinds of optical MEMS devices because of their applications in optical communication industry and fiber-optic sensors. Efficient optical coupling is the key to develop optical MEMS devices for optical communication and sensing, however, efficient coupling between MEMS actuators or sensing structures and optical fibers is a challenging job. Besides high performance MEMS actuators and coupling micro-optics are needed, the MEMS structures should adapt to coupling micro-optics. The torsion MEMS micro-mirrors and gratings can couple with fiber collimators at low insertion loss, therefore, the torsion MEMS structure is a good choice for optical MEMS devices, especially for continuous or multi-level controlled devices. In this paper, we report three kinds of optical MEMS devices based on silicon torsion micro structure, MEMS variable optical attenuator (VOA), 1×8 MEMS optical switch and high-speed MEMS torsion blazed grating , which have been developed recently in our optical MEMS research group. The three devices are coupled with optical fibers by optical fiber collimators, so low loss coupling can be achieved.

Wu, Yaming; Xu, Jing; Li, Sihua; Wan, Zhujun; Mu, Canjun

2008-03-01

400

Torsion of an indirect hernia sac causing acute scrotum  

Microsoft Academic Search

A 6-year-old boy presented with an acute scrotum and was found at surgical exploration to have torsion and infarction of an indirect hernia sac. This represents the sixth reported case of this entity in the literature. The pediatric surgical specialist and those in the acute care setting should be aware of this consideration in the differential diagnosis of the acute

Jeremy B Myers; Mark A Lovell; Robert S Lee; Peter D Furness; Martin Koyle

2004-01-01

401

INVESTIGATION OF STEEL SAMPLES DESTRUCTION PROCESS UNDER TORSION LOADING  

Microsoft Academic Search

Acoustical characteristics of steel samples under torsion momentum beyond the elasticity range were investigated. Longitudinal elastic wave propagation velocities V were measured along the axes of every sample which was twisted at some number of turns (from 0 to 5). The relative error of this measurements was equal to 0,01%. The mass of every sample was evaluated by the help

Nizhny Novgorod Branch; Nizhny Novgorod

402

Quaternionic Torsion Geometry, Superconformal Symmetry and T-duality  

SciTech Connect

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.

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

2009-02-02

403

A circumferential crack in a cylindrical shell under torsion  

Microsoft Academic Search

The fully anti-symmetric problem for a cylindrical shell with a circumferential crack is considered. The solution of the problem is reduced to that of a system of singular integral equations of the first kind. As an example the torsion of the cylinder is discussed and membrane and bending components of the stress intensity factor ratio are given.

F. Erdogan; M. Ratwani

1972-01-01

404

Two-axis angular effector  

DOEpatents

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.

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

405

Variable Distance Angular Symbology Reader  

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

406

The Rotation-Torsion Spectrum of CH_2DOH  

NASA Astrophysics Data System (ADS)

Due to the asymmetry of the CH_2D group, the internal rotation problem in the partially deuterated species of methanol CH_2DOH is a complicated one as, unlike in the normal species CH_3OH, the inertia tensor depends on the angle of internal rotation. The CH_2DOH species also displays a dense far infrared torsional spectrum difficult to assign. Recently 38 torsional subbands of CH_2DOH have been identified, but for most of them there is neither an assignment nor an analysis of their rotational structure. In this paper an analysis of the rotation-torsion spectrum of CH_2DOH will be presented. The rotational structure of 23 torsional subbands have been assigned. These subbands are ? v_t &ge 1 perpendicular subbands with a value of v'_t up to 10b and values of K' and K'' ranging from 0 to 9. For all subbands, the Q-branch was assigned, for 3 subbands, the R- and P-branches could also be found. The results of the rotational analysis with an expansion in J(J+1) of the new subbands and of already observed ones will be presented. When available, microwave lines within the lower torsional level, recorded in this work or already measured, were added to the data set. A theoretical approach aimed at calculating the rotation-torsion energy levels has also been developed. It is based on an expansion in terms of rotation-torsion operators with C_s symmetry and accounts for the dependence of the inertia tensor on the angle of internal rotation. This approach will be used to carry out a preliminary global analyses of the wavenumbers and of the frequencies. Lauvergnat, Coudert, Klee, and Smirnov, J. Mol. Spec. 256 (2009) 204. Quade, Liu, Mukhopadhyay, and Su, J. Mol. Spec. 192 (1998) 378; Mukhopadhyay, J. Mol. Struct. 695-696 (2004) 357. Liu and Quade, J. Mol. Spec. 146 (1991) 252 Mukhopadhyay et al., J. Chem. Phys. 116 (2002) 3710.

Hilali, A. El; Coudert, L. H.; Margulès, L.; Motiyenko, R.; Klee, S.

2010-06-01

407

Effects of Torsion on Intervertebral Disc Gene Expression and Biomechanics, Using a Rat Tail Model  

PubMed Central

Study Design In vitro and in vivo rat tail model to assess effects of torsion on intervertebral disc biomechanics and gene expression. Objective Investigate effects of torsion on promoting biosynthesis and producing injury in rat caudal intervertebral discs. Summary of Background Data Torsion is an important loading mode in the disc and increased torsional range of motion is associated with clinical symptoms from disc disruption. Altered elastin content is implicated in disc degeneration, but its effects on torsional loading are unknown. Although effects of compression have been studied, the effect of torsion on intervertebral disc gene expression is unknown. Methods In vitro biomechanical tests were performed in torsion on rat tail motion segments subjected to 4 treatments: elastase, collagenase, genipin, control. In vivo tests were performed on rats with Ilizarov-type fixators implanted to caudal motion segments with five 90-minute loading groups: 1 Hz cyclic torsion to ±5°, ±15°, and ±30°, static torsion to +30°, and sham. Anulus and nucleus tissues were separately analyzed using qRT-PCR for gene expression of anabolic, catabolic, and proinflammatory cytokine markers. Results In vitro tests showed decreased torsional stiffness following elastase treatment and no changes in stiffness with frequency. In vivo tests showed no significant changes in dynamic stiffness with time. Cyclic torsion upregulated elastin expression in the anulus fibrosus. Upregulation of TNF-? and IL-1? was measured at ±30°. Conclusion We conclude that strong differences in the disc response to cyclic torsion and compression are apparent with torsion increasing elastin expression and compression resulting in a more substantial increase in disc metabolism in the nucleus pulposus. Results highlight the importance of elastin in torsional loading and suggest that elastin remodels in response to shearing. Torsional loading can cause injury to the disc at excessive amplitudes that are detectable biologically before they are biomechanically.

Barbir, Ana; Godburn, Karolyn E.; Michalek, Arthur J.; Lai, Alon; Monsey, Robert D.; Iatridis, James C.

2010-01-01

408

Spin chains and string theory  

Microsoft Academic Search

Recently, an impressive agreement was found between anomalous dimen- sions of certain operators in N = 4 SYM and rotating strings with two angular mo- menta in the bulk of AdS5 × S5. A one-loop field theory computation, which involves solving a Heisenberg chain by means of the Bethe ansatz agrees with the large angular momentum limit of a rotating

Martin Kruczenski

409

Delamination behavior of quasi-isotropic graphite epoxy laminates subjected to tension and torsion loads  

NASA Technical Reports Server (NTRS)

Sixteen and thirty-two ply quasi-isotropic laminates fabricated from AS4/3501-6 were subjected to pure tension, simultaneous tension and torsion, and torsion fatigue. Layups tested were (45 sub n/-45 sub n/O sub n/90 sub n) sub s, with n = 2 or 4. A torsion damage pattern consisting of a localized matrix crack and delaminations was characterized, and the measured torsional stiffnesses were compared with calculated values. It was found that a combination of tension and torsion led to failure at smaller loads than either type of deformation acting alone. Further work is required to determine the exact form of the failure criterion.

Hinkley, J. A.; Obrien, T. K.

1992-01-01

410

Torsional vibration measurements on rotating shaft system using laser doppler vibrometer  

NASA Astrophysics Data System (ADS)

In this work, a laser torsional vibrameter was used to measure the torsion vibration of a rotating shaft system under electrical network impact. Based on the principles of laser Doppler velocimetry, the laser torsional vibrometer (LTV) are non-contact measurement of torsional oscillation of rotating shafts, offering significant advantages over conventional techniques. Furthermore, a highly complex shafting system is analyzed by a modified Riccati torsional transfer matrix. The system is modeled as a chain consisting of an elastic spring with concentrated mass points, and the multi-segments lumped mass model is established for this shafting system. By the modified Riccati torsional transfer matrix method, an accumulated calculation is effectively eliminated to obtain the natural frequencies. The electrical network impacts can activize the torsional vibration of shaft system, and the activized torsion vibration frequencies contained the natural frequencies of shaft system. The torsional vibrations of the shaft system were measured under electrical network impacts in laser Doppler torsional vibrometer. By comparisons, the natural frequencies by measurement were consistent with the values by calculation. The results verify the instrument is robust, user friendly and can be calibrated in situ. The laser torsional vibrometer represents a significant step forward in rotating machinery diagnostics.

Xiang, Ling; Yang, Shixi; Gan, Chunbiao

2012-11-01

411

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

NASA Astrophysics Data System (ADS)

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.

Garcia de Andrade, L. C.

412

Form factors and non-local multiplicative anomaly for fermions with background torsion  

NASA Astrophysics Data System (ADS)

We analyse the multiplicative anomaly (MA) in the case of quantized massive fermions coupled to a background torsion. The one-loop effective action (EA) can be expressed in terms of the logarithm of the determinant of the appropriate first-order differential operator acting in the spinors space. Simple algebraic manipulations on determinants must be used in order to apply properly the Schwinger–DeWitt technique, or even the covariant perturbation theory (Barvinsky and Vilkovisky, 1990), which is used in the present work. By this method, we calculate the finite non-local quantum corrections, and analyse explicitly the breakdown of those algebraic manipulations on determinants, called by MA. This feature comes from the finite non-local EA, but does not affect the results in the UV limit, in particular, the beta-functions. Similar results were also obtained in previous papers but for different external fields (QED and scalar field).

de Berredo-Peixoto, G.; Espinosa Maicá, A.

2014-06-01

413

Mechanical and microstructural development of Carrara marble with pre-existing deformation history in torsion experiments  

NASA Astrophysics Data System (ADS)

The deformation behaviour of Carrara marble has been studied mostly by performing deformation experiments on initially undeformed samples. In this study, torsion experiments on Carrara marble with a pre-existing deformation history have been conducted and analysed in terms of both mechanical and microstructural development. Torsion experiments have been conducted to deform initially deformed Carrara marble samples until a bulk shear strain of gamma 1 or 2.6 was reached. For Carrara marble experiments typically yielding is followed by strain hardening until a peak stress is reached around a shear strain gamma = 1 , after which a weakening phase occurs. Weakening gradually develops into a steady-state creep. During hardening, a shear microstructure and CPO develops; afterwards dynamic recrystallization becomes increasingly effective resulting in pervasively recrystallized microstructure and recrystallization CPO at gamma 5 and higher. Starting material of the new experiments are sandwich samples consisting of three equally sized segments: a top segment previously deformed counter clockwise, an undeformed centre segment and a previously clockwise deformed segment in the bottom. Shear strain of the deformed bottom and top segments are equal in magnitude but opposite in sense and correspond with the shear strain of the actual experiments (e.g. sample of the gamma 1 experiment, consists of initially gamma 1 deformed top and bottom segments). All torsion experiments were conducted using a Paterson type internally heated gas-medium deformation apparatus equipped with a torsion actuator, under temperature and pressure conditions of 1000K and 300 MPa, respectively. Angular displacement rates during the experiments correspond to a strain rate of 3.0x10-4 s-1 at the outer cylinder periphery. The second deformation event imposed on the sandwich sample is always counter clockwise (or dextral). The sandwich experiment to gamma 1 shows a weakly developed strain partitioning between the three segments. Most strain is accommodated in the initially undeformed centre segment, whereas the top segment appears least deformed during this experiment. For the higher strain experiment (gamma 2.6), strain partitioning is enhanced and reversed, i.e. maximum and minimum strains are accommodated by the top and centre segment respectively. This strain partitioning can be explained by the strength evolution of Carrara marble with shear strain. For Carrara marble at gamma 1, deformation is harder than undeformed, due to hardening of the material caused by shearing microstructure. At higher strain, Carrara marble starts recrystallizing instead of shearing, weakening the material. Therefore, for the gamma 2.6 experiment deformation is easier in the initially deformed segments than in the undeformed segment. Consequently, strain partitioning can be an onset for strain localization. The observed microstructures reflect the finite strain (pre-existing plus added) in the sample segments of same sense of shear, which are shear microstructures for 0+1 and 1+1, and recrystallization microstructures for 0+2.6, and 2.6 + 2.6. For the segments of reversed sense of shear, the segment 1-1 appears like undeformed with respect to grain shape, but contains larger amounts of intragranular defects; the segment 2.6-2.6 is mostly recrystallized to a fine grained matrix with some ‘un-stretched' clasts embedded. Similarly, the CPO in segments 0+1 and 1+1 resembles shear textures, while segments 0+2.6, 2.6+2.6 and 2.6-2.6 show recrystallization CPO. In segment 1-1, the pre-existing shear CPO is nearly annihilated by the second deformation in reversed sense.

Bruijn, R. H. C.; Burlini, L.; Kunze, K.

2009-04-01

414

Angular Quantization of the Sine-Gordon Model at the Free Fermion Point  

Microsoft Academic Search

The goal of this paper is to analyse the method of angular quantization for the Sine-Gordon model at the free fermion point, which is one of the most investigated models of the two-dimensional integrable field theories. The angular quantization method (see hep-th\\/9707091) is a continuous analog of the Baxter's corner transfer matrix method. Investigating the canonical quantization of the free

S. Khoroshkin; A. LeClair; S. Pakuliak

1999-01-01

415

Optical Diffractive Memories: Angular Selectivity and Diffraction Efficiency in Dichromated Gelatin  

Microsoft Academic Search

Two thousand images of resolution 512×512 pixels as a regular matrix pattern of 10×10 elements are stored, where each element is angularly multiplexed 20 times in a 25 ?m thickness of dichromated gelatin emulsion without cross-talk effect. The surface area of the matrix is 1 cm2. We show good concordance of the angular selectivity between the experimental result and theory.

Harry Ramenah; Poul Bertrand; Patrick Meyrueis

1995-01-01

416

Rotation of Electromagnetic Fields and the Nature of Optical Angular Momentum  

PubMed Central

The association of spin and orbital angular momenta of light with its polarization and helical phase fronts is now well established. The problems in linking this with electromagnetic theory, as expressed in Maxwell's equations, are rather less well known. We present a simple analysis of the problems involved in defining spin and orbital angular momenta for electromagnetic fields and discuss some of the remaining challenges. Crucial to our investigation is the duplex symmetry between the electric and magnetic fields.

Barnett, Stephen M.

2010-01-01

417

Propagation dependence of chirp in Gaussian pulses and beams due to angular dispersion.  

PubMed

The chirp acquired by a Gaussian ultrashort pulse due to angular dispersion, unlike that of plane waves, increases nonlinearly with propagation distance and eventually asymptotes to a constant. However, this interesting result has never been directly measured. In this Letter, we use two-dimensional spectral interferometry to measure the propagation dependence of the chirp for Gaussian ultrashort pulses and beams with angular dispersion. The measured chirp as a function of propagation distance agreed well with theory. This work verifies both an equation and a measurement technique that will be useful for predicting or determining the pulse's chirp in ultrafast optics experiments that contain angular dispersion. PMID:19340185

Li, Derong; Zeng, Shaoqun; Luo, Qingming; Bowlan, Pamela; Chauhan, Vikrant; Trebino, Rick

2009-04-01

418

Comment on ``Geometric absorption of electromagnetic angular momentum'', C. Konz, G. Benford  

NASA Astrophysics Data System (ADS)

The core theorem on which the above paper is centred - that a perfectly conducting body of revolution absorbs no angular momentum from an axisymmetric electromagnetic wave field - is in fact a special case of a more general result in electromagnetic scattering theory. In addition, the scaling of the efficiency of transfer of angular momentum to an object with the wavelength and object size merits further discussion. Finally, some comments are made on the choice of terminology and the erroneous statement that a circularly polarized plane wave does not carry angular momentum.

Nieminen, Timo A.

2004-05-01

419

Dual electromagnetism: helicity, spin, momentum and angular momentum  

NASA Astrophysics Data System (ADS)

The dual symmetry between electric and magnetic fields is an important intrinsic property of Maxwell equations in free space. This symmetry underlies the conservation of optical helicity and, as we show here, is closely related to the separation of spin and orbital degrees of freedom of light (the helicity flux coincides with the spin angular momentum). However, in the standard field-theory formulation of electromagnetism, the field Lagrangian is not dual symmetric. This leads to problematic dual-asymmetric forms of the canonical energy-momentum, spin and orbital angular-momentum tensors. Moreover, we show that the components of these tensors conflict with the helicity and energy conservation laws. To resolve this discrepancy between the symmetries of the Lagrangian and Maxwell equations, we put forward a dual-symmetric Lagrangian formulation of classical electromagnetism. This dual electromagnetism preserves the form of Maxwell equations, yields meaningful canonical energy-momentum and angular-momentum tensors, and ensures a self-consistent separation of the spin and orbital degrees of freedom. This provides a rigorous derivation of the results suggested in other recent approaches. We make the Noether analysis of the dual symmetry and all the Poincaré symmetries, examine both local and integral conserved quantities and show that only the dual electromagnetism naturally produces a complete self-consistent set of conservation laws. We also discuss the observability of physical quantities distinguishing the standard and dual theories, as well as relations to quantum weak measurements and various optical experiments.

Bliokh, Konstantin Y.; Bekshaev, Aleksandr Y.; Nori, Franco

2013-03-01

420

Two Model Hamiltonians for Torsion-Inversion Tunneling in the Ch-Stretch Vibrationally Excited States of Methylamine  

NASA Astrophysics Data System (ADS)

In methylamine (CH_3NH_2), there are six equivalent mimina that are connected by torsion and inversion tunneling. In the G_1_2 molecular symmetric group, there are four species, A = {A_1, A_2}, B = {B_1, B_2}, E_1 and E_2 that combine with distinct nuclear states. The ground vibrational state of CH_3NH_2 is split by torsion and inversion tunneling into a multiplet pattern of four distinct energy levels. The experimental tunneling pattern for CH_3NH_2 in the ?_1_1 asymmetric CH-stretch fundamental has been previously reported at this meeting. In the experimental pattern, the degenerate species (E_1 and E_2) are at the top and bottom of the multiplet and the non-degenerate species (B and A) are between them. In this work, we present two models for the torsion-inversion tunneling behavior in the CH-stretch excited states. Each model includes the lowest order torsion-inversion-vibration interactions available in the context of the model. The first model, which extends Hougen{'s} treatment of methanol, couples the two vibrational angular momentum components of the asymmetric CH-stretches to the large-amplitude motion to yield predicted tunneling patterns for the ?_2 and ?_1_1 fundamentals. This model gives similar patterns for ?_2 and ?_1_1, in which E_1 and E_2 are in the middle of the multiplet and the non-degenerate species are at the top and bottom. The second model, which follows conceptually Wang and Perry{'s} local mode treatment of methanol, couples the three local CH-stretches to each other and to the large-amplitude motion to yield the tunneling patterns for the ?_2, ?_3 and ?_1_1 fundamentals. For this model, we found that, for ?_2 and ?_1_1, both E_1 and E_2 are at the bottom of the multiplet, in contrast to ?_3 and the ground state where they are at the top. The fact that neither model reproduces the observed tunneling pattern for ?_1_1, suggests that additional isolated perturbations or systematic interactions are present in the experimental spectra. V.V. Ilyshin et al. J. Mol. Spectrosc. 251(56-63), 2008. J.T. Hougen J. Mol. Spectrosc. 207(60-65), 2001. X. Wang and D.S. Perry J. Chem. Phys. 109(10795-10805), 1998.

Dawadi, Mahesh B.; Perry, David S.

2012-06-01

421

The effects of lateral-torsional coupling on the nonlinear dynamic behavior of a rotating continuous flexible shaft-disk system with rub-impact  

NASA Astrophysics Data System (ADS)

This study investigates the lateral-torsional coupling effects on the nonlinear dynamic behavior of a rotating flexible shaft-disk system. The system is modeled as a continuous shaft with a rigid disk in its mid span. Coriolis and centrifugal effects due to shaft flexibility are also included. The partial differential equations of motion are extracted under the Rayleigh beam theory. The assumed mode method is used to discretize partial differential equations and the resulting equations are solved via numerical methods. The analytical methods used in this work include time series, phase plane portrait, power spectrum, Poincaré map, bifurcation diagrams, and Lyapunov exponents. The main objective of the present study is to investigate the torsional coupling effects on the chaotic vibration behavior of a system. Periodic, sub-harmonic, quasi-periodic, and chaotic states can be observed for cases with and without torsional effects. As demonstrated, inclusion of the torsional-lateral coupling effects can primarily change the speed ratios at which rub-impact occurs. Also, substantial differences are shown to exist in the nonlinear dynamic behavior of the system in the two cases.

Khanlo, H. M.; Ghayour, M.; Ziaei-Rad, S.

2013-06-01

422

Practical formula for the radiated angular momentum  

Microsoft Academic Search

We present a simple formula for the radiated angular momentum based on a spin-weighted spherical harmonic decomposition of the Weyl scalar representing outgoing radiation in the Kinnersley tetrad. We test our formula by measuring the radiated angular momentum from three simulations of nonspinning equal-mass-black-hole binaries with orbital angular momentum aligned along the x, y, and z axes, respectively. We find

Carlos O. Lousto; Yosef Zlochower

2007-01-01

423

Practical formula for the radiated angular momentum  

Microsoft Academic Search

We present a simple formula for the radiated angular momentum based on a spin-weighted spherical harmonic decomposition of the Weyl scalar psi4 representing outgoing radiation in the Kinnersley tetrad. We test our formula by measuring the radiated angular momentum from three simulations of nonspinning equal-mass black-hole binaries with orbital angular momentum aligned along the x, y, and z axes, respectively.

Carlos O. Lousto; Yosef Zlochower

2007-01-01

424

Angularly parameterized macromodel extraction for unconstrained microstructures  

NASA Astrophysics Data System (ADS)

In this paper, we present an angularly parameterized model order reduction (APMOR) technique for macromodel extraction of unconstrained microstructures by combining a new, iterated IRS (improved reduced system) method with coordinate transformation theory. The extracted macromodels are encapsulated in the MAST hardware description language and can be exported automatically as components which can be inserted directly into an analog circuit simulator for dynamics simulation. An in-plane micro accelerometer including four variable cross-section folded beams is used to demonstrate the proposed macromodeling method. The folded beams are treated as unconstrained microstructures, and numerical simulation results in a SABER simulator show that the macromodels can dramatically reduce the computation cost while capturing the device behavior faithfully. Compared with FEM results, the relative error is less than 1.4%, while the computational efficiency improves about 22 times. Once the macromodel of one of the folded beams is obtained, the macromodels of all other folded beams can be obtained easily by setting the corresponding angle parameters. With the help of an APMOR technique and the existing model library which is developed in our previous work, the hybrid system-level model of the in-plane micro accelerometer can be constructed rapidly, and the scale factor of the accelerometer is simulated. Compared with experimental results, the relative error is about 8.16%.

Xu, Jinghui; Yuan, Weizheng; Chang, Honglong; Ma, Binghe; Yu, Yiting

2008-11-01

425

Angular Power Spectrum in Modular Invariant Inflation Model  

SciTech Connect

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.

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

426

Correlation between angular anisotropy and fragment mass in 15 MeV proton-induced fission of 232Th  

NASA Astrophysics Data System (ADS)

The angular distributions of 15 fission fragments were radiochemically obtained in the 15 MeV proton-induced fission of 232Th. It was found that the angular anisotropies of symmetrically divided fission fragments were smaller than those of asymmetrically divided fragments. With the assumption of two kinds of saddle points, one leading to a symmetric mass division and the other to an asymmetric division, the observed angular anisotropies could be well reproduced. NUCLEAR REACTIONS, FISSION Angular distribution in 15 MeV proton-induced fission of 232Th, Bohr's channel theory, two kinds of saddle point configurations, mass division.

Kudo, H.; Nagame, Y.; Nakahara, H.; Miyano, K.; Kohno, I.

1982-02-01

427

MAGNETOSEISMOLOGY: EIGENMODES OF TORSIONAL ALFVEN WAVES IN STRATIFIED SOLAR WAVEGUIDES  

SciTech Connect

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.

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

428

The Torsion of Members Having Sections Common in Aircraft Construction  

NASA Technical Reports Server (NTRS)

Within recent years a great variety of approximate torsion formulas and drafting-room processes have been advocated. In some of these, especially where mathematical considerations are involved, the results are extremely complex and are not generally intelligible to engineers. The principal object of this investigation was to determine by experiment and theoretical investigation how accurate the more common of these formulas are and on what assumptions they are founded and, if none of the proposed methods proved to be reasonable accurate in practice, to produce simple, practical formulas from reasonably correct assumptions, backed by experiment. A second object was to collect in readily accessible form the most useful of known results for the more common sections. Formulas for all the important solid sections that have yielded to mathematical treatment are listed. Then follows a discussion of the torsion of tubular rods with formulas both rigorous and approximate.

Trayer, George W; March, H W

1930-01-01

429

Intestinal torsion causing chylous ascites: a rare occurrence.  

PubMed

Intestinal torsion and chylous ascites are very rarely associated. We present the case of a 19-year-old man who presented with acute abdomen. Computed tomography of his abdomen showed features suggestive of intestinal torsion. Chylous ascites was incidentally discovered on exploratory laparotomy. The chylous fluid was drained, the small bowel detorted and the coloduodenal adhesion band taken down. The patient's retroperitoneum was explored to exclude occult masses and malformations of the lymphatics. Post surgery, the patient recovered uneventfully. In this case, we postulate that intestinal malrotation had caused the obstruction of the lymphatic flow from the mesenteric lymphatic channels, leading to the exudation of chyle, which then resulted in the accumulation of chylous fluid in the peritoneal cavity. It is important to exclude the more common causes of atraumatic chylous ascites, such as enlarged retroperitoneal lymph nodes or lymphatic malformations. PMID:23624462

Koh, Ye Xin; Chng, Jack Kian; Tan, Hwei Ching; Chung, Alexander Yaw Fui

2013-04-01

430

Torsion of the uterus in an Awassi ewe.  

PubMed

The treatment of a 4-year-old pluriparous Awassi ewe with torsion of the uterus at parturition is described. At presentation, all the signs of imminent parturition were present and the rostral portion of the vagina was spirally twisted to the right causing complete stenosis of the birth canal with no foetal fluid exiting the uterus. A 360 degrees clockwise uterine torsion was diagnosed. Attempted treatment by rotation of the ewe's body proved unsuccessful. The condition was then corrected surgically via a left flank caesarean operation, and a dead foetus and foetal membranes were removed. The animal made an uneventful recovery and the sutures were removed on the 12th postoperative day. PMID:10590791

Ijaz, A; Talafha, A Q

1999-10-01

431

Nonlinear finite amplitude torsional vibrations of cantilevers in viscous fluids  

NASA Astrophysics Data System (ADS)

In this paper, we study torsional vibrations of cantilever beams undergoing moderately large oscillations within a quiescent viscous fluid. The structure is modeled as an Euler-Bernoulli beam, with thin rectangular cross section, under base excitation. The distributed hydrodynamic loading experienced by the vibrating structure is described through a complex-valued hydrodynamic function which incorporates added mass and fluid damping elicited by moderately large rotations. We conduct a parametric study on the two dimensional computational fluid dynamics of a pitching rigid lamina, representative of a generic beam cross section, to investigate the dependence of the hydrodynamic function on the governing flow parameters. As the frequency and amplitude of the oscillation increase, vortex shedding and convection phenomena increase, thus resulting into nonlinear hydrodynamic damping. We derive a handleable nonlinear correction to the classical hydrodynamic function developed for small amplitude torsional vibrations for use in a reduced order nonlinear modal model and we validate theoretical results against experimental findings.

Aureli, Matteo; Pagano, Christopher; Porfiri, Maurizio

2012-06-01

432

Dark energy fifth forces in torsion pendulum experiments  

NASA Astrophysics Data System (ADS)

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 Eöt-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 Eöt-Wash experiment, and show that this experiment will exclude a wide range of quantum-stable models.

Upadhye, Amol

2012-11-01

433

[Experimental testicular torsion: its effect on the contralateral testicle].  

PubMed

The purpose of this project is to determine the lesion in contralateral testis after unilateral testicular torsion. For that is reproduced the lesion in an experimental model animal using 35-45 days old Wistar rats. The study of the contralateral testis is performed 30-35 days after lesion, once orchiectomy with histopathological and ultrastructural analysis, was made. We observed zonal tubular atrophy, alteration of spermatogenesis, abnormal formation of spermatozoa and death cellular by apoptosis. PMID:10624041

Paredes Esteban, R M; Ramírez Chamond, R; Carracedo Añón, J; Salas Molina, J; Hervas Rodríguez, J; Garrido Pérez, J I; Ocaña Losa, J M

1999-10-01

434

Ultrahigh torsional stiffness and strength of boron nitride nanotubes.  

PubMed

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

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

2012-12-12

435

Optical vortices in twisted elliptical optical fibers with torsional stress.  

PubMed

In the present paper we have derived the analytical expressions for the modes of twisted elliptical fibers with torsional mechanical stress at various relationships of the fiber parameters. It was shown that circularly polarized optical vortices with the topological charges ±1 can propagate in elliptical fibers as generic modes if ellipticity and the twist-induced circular birefringence suppress the spin-orbit interaction. A comparison of the obtained results with the corresponding results for spun elliptical fibers is made. PMID:22505095

Alexeyev, Constantine; Barshak, Elena; Fridman, Yurii; Yavorsky, Maxim

2012-04-01

436

Electrostatic micro torsion mirrors for an optical switch matrix  

Microsoft Academic Search

We have developed a new type of compact optical switch using silicon micromachining technique. Torsion mirrors (300 ?m×600 ?m) supported by thin polysilicon beams (16 ?m wide, 320 ?m long, and 0.4 ?m thick) are arranged in a 2×2 matrix (total size 3 mm×5 mm, t 0.3 mm). The mirrors are independently attracted by electrostatic force of applied bias voltage

Hiroshi Toshiyoshi; Hiroyuki Fujita

1996-01-01

437

Damage of Glulam Beams Under Cyclic Torsion: Experiments and Modelling  

Microsoft Academic Search

The aim of this paper is to study the behaviour and the lifetime of glued-laminated small scale beams (GL) submitted to cyclic\\u000a torsion. Experimental programmes have been carried out: periodic triangular alternate torques with varying amplitude is applied\\u000a to GL samples with rectangular cross section. Experimental lifetime is presented by semi logarithmic SL-N curves (SL is the\\u000a maximum torque stress

Myriam Chaplain; Zahreddine Nafa; Mohamed Guenfoud

438

Simple currents versus orbifolds with discrete torsion - a complete classification  

Microsoft Academic Search

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

M. Kreuzer; A. N. Schellekens

1994-01-01

439

Landfill liner interface strengths from torsional-ring-shear tests  

Microsoft Academic Search

A torsional-ring-shear apparatus and test procedure are described for measuring soil\\/geosynthetic and geosynthetic\\/geosynthetic interface strengths. Typical interface strengths are presented for a double-composite liner system and the relevancy of ring-shear strengths is illustrated using the slope failure at the Kettleman Hills Waste Repository, Kettleman City, Calif. The results of undrained ring-shear tests show that for a clay\\/geomembrane interface: (1) interface

Timothy D. Stark; Alan R. Poeppel

1994-01-01

440

Video-oculography For Measurement Of Torsional Nystagmus  

Microsoft Academic Search

It shows a description of a non-invasive method for the study and analysis of Torsional Nystagmus, using imaging processing computer. I. INTRODUCTION The eyes movements plays an important role, not only in medical area, by the diagnostic utility in the detection of alterations of ocular muscies(l,2), but also in other areas oE scientific application, such as: Design Engineering of control

Emesto Suaste; U. Cajica; Palmua Rivera

1993-01-01

441

A high sensitivity z-axis torsional silicon accelerometer  

Microsoft Academic Search

This paper presents a high sensitivity silicon micromachined capacitive accelerometer fabricated using a three mask, dissolved wafer process. High electrical sensitivity is obtained by using high aspect-ratio comb fingers with narrow air gaps of 2 ?m and large overlap area of 12 ?m×300 ?m. Torsional suspension beams 150 ?m long with a cross-sectional area of 12 ?m×3 ?m are used

Arjun Selvakumar; Farrokh Ayazi; Khalil Najafi

1996-01-01

442

Reaction-induced strain localization: Torsion experiments on dolomite  

Microsoft Academic Search

We investigated the mechanical behaviour and microstructural evolution of a dolomite marble from Mt. Frerone (Adamello, N-Italy) during decarbonation to calcite and periclase in torsion experiments. Tests were performed in a Paterson gas-medium apparatus on cylindrical samples of 10 mm diameter and 10 mm length. Experiments were conducted at 800 °C, 300 MPa confining pressure under both vented and non-vented conditions, up to a

Claudio Delle Piane; Luigi Burlini; Bernard Grobety

2007-01-01

443

A test of lorentz invariance using a torsion pendulum  

Microsoft Academic Search

Summary  A search has been made for a preferred frame of reference in space. We assume that the velocityV of the earth in this frame is coupled to the spin of an electron through a termG\\u000a V·?. The sensing element was a bar magnet on a torsion fiber. By looking for diurnal variations in the orientation of the pendulum,\\u000a we can

P. R. Phillips; D. Woolum

1969-01-01

444

Torsion of a cylindrical composite shaft of finite length  

NASA Astrophysics Data System (ADS)

The problem of the torsion of a multilayer composite hollow cylindrical shaft of finite length is analyzed using the general approach proposed by Ufland (1976). This approach and the averaging method are used to obtain a new generalized integral equation which is then used to obtain an analytical solution for the problem. In the particular case of a homogeneous material, the generalized integral representation is shown to reduce to known relations, which have been used in a earlier study (Arutiunian et al., 1986).

Bardzokas, D. Ia.; Kalamkarov, A. L.; Rudakova, O. B.

1992-02-01

445

Torsion of an indirect hernia sac causing acute scrotum.  

PubMed

A 6-year-old boy presented with an acute scrotum and was found at surgical exploration to have torsion and infarction of an indirect hernia sac. This represents the sixth reported case of this entity in the literature. The pediatric surgical specialist and those in the acute care setting should be aware of this consideration in the differential diagnosis of the acute scrotum. PMID:14694389

Myers, Jeremy B; Lovell, Mark A; Lee, Robert S; Furness, Peter D; Koyle, Martin

2004-01-01

446

Calibration of combined bending-torsion fatigue reliability data reduction  

NASA Technical Reports Server (NTRS)

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.

Kececioglu, D.; Mcconnell, J. B.

1969-01-01

447

Discrete Torsion in Singular G_2-Manifolds and Real LG  

Microsoft Academic Search

We investigate strings at singularities of G_2-holonomy manifolds which arise in Z_2 orbifolds of Calabi-Yau spaces times a circle. The singularities locally look like R^4\\/Z_2 fibered over a SLAG, and can globally be embedded in CICYs in weighted projective spaces. The local model depends on the choice of a discrete torsion in the fibration, and the global model on an

Radu Roiban; Christian Romelsberger; Johannes Walcher

2002-01-01

448

ILLIAC 4 and lifting surface theory with boundary layer  

NASA Technical Reports Server (NTRS)

Aerodynamic flutter and a re-written computer program for its study are discussed. Data cover: (1) lifting surface theory with boundary layer, (2) incompressible, two dimensional, unsteady flow with control surfaces, (3) improved unsteady theory, (4) combined transonic airfoil thickness and shear layer thickness effects, and (5) bending-torsion flutter calculations.

Dowell, E. H.

1976-01-01

449

Fission-fragment angular distributions for the 19F + 208Pb near- and sub-barrier fusion-fission reaction  

Microsoft Academic Search

Fission cross sections and angular distributions have been measured for the 19F + 208Pb reaction at bombarding energies from 83 to 105 MeV. The fission excitation function is well reproduced on the basis of the coupled-channels theory. The fission-fragment angular distributions are calculated in terms of the transition-state theory, with the transmission coefficients extracted from the excitation function calculation. It

Huanqiao Zhang; Zuhua Liu; Jincheng Xu; Kan Xu; Jun Lu; Ming Ruan

1990-01-01

450

Torsional vibration analysis of turbine-generator-blade coupled system  

SciTech Connect

Turbine-generator sets are major components of electricity generating power plants. Pretwisted turbine blades, fixed on a rotating shaft by means of mounting disks, vibrate in both tangential and axial directions. The tangential component of blade vibrations is coupled with torsional vibrations of the shaft. This problem of a coupled shaft-blade torsional vibration in turbine-generator sets requires an equivalent reduction modeling technique used for coupled vibrating systems; however, to date, the shaft system and the blade system were modeled separately. The designers of a rotating shaft system analyze its torsional vibration ignoring the flexibility of the blade and of the disks. The shaft is modeled as a beam element using the finite element method (FEM). This FEM beam model is then used to calculate and design the shaft natural frequencies such that resonance is avoided with unbalanced torque excitations which have twice the line frequency (2f). This paper shows explicitly how to determine the modeling masses and spring constants to obtain the equivalent reduction of the real sub-system.

Matsushita, O.; Namura, K. Yoshida, T. (Mechanical Engineering Research Lab., Hitachi, Ltd., 502 Kandatsu-machi, Tsuchiura-shi, Ibaraki (JP)); Kaneko, R.; Okabe, A. (Hitachi Works, Hitachi, Ltd., 3-1-1 Saiwai-cho, Hitachi-shi, Ibaraki (JP))

1989-01-01

451

Metal-carbon nanotube composite nanoelectromechanical torsional resonators  

NASA Astrophysics Data System (ADS)

Metallic based nanoelectromechanical systems (NEMS) resonator structures are of interest due to higher optical reflectivity, ductility, and conductivity compared to insulator- and semiconductor- based NEMS structures. We present NEMS torsional resonator structures fabricated from aluminum-carbon nanotube (CNT) and palladium-CNT composites. Metal and metal-CNT NEMS structures are released from III-V based substrates. The resonators are electrostatically driven and are detected at room temperatures under moderate vacuum conditions using optical modulation techniques. We note significant differences in the resonant frequencies (f0) and the quality factors (Q) between metal and metal-CNT NEMS torsional resonators. Aluminum based structures with paddle dimensions of ˜5 micron x ˜5 micron, with support beams of ˜1 micron x ˜3 micron, show a fundamental resonant frequency corresponding to translational mode of 1.7 MHz with Q of 20, while Al-CNT based structures of same dimensions show f0 of 3 MHz and Q of 50, as a typical example. We will further discuss the effects on the mechanical properties of metallic NEMS torsional resonators due to addition of CNT. parkyd@phya.snu.ac.kr

Duck Kim, Young; Hong, Seung Sae; Bak, Jung Hoon; Lee, Byung Yang; Cho, Sung Woon; Suh, Ki Sung; Hong, Seunghun; Park, Yun Daniel

2007-03-01

452

X-linked recessive torsion dystonia in the Philippines.  

PubMed

The occurrence of an X-linked form of torsion dystonia in the Philippines was demonstrated by the genetic and biochemical analysis of affected males and their relatives. Thirty-six affected males were ascertained in 21 families by clinical neurologic evaluation. The mean age-of-onset of dystonia was 37.9 years with a range from 12 to 52 years. Neurologic symptoms began focally and progressed to either segmental or generalized involvement in all cases. Generalized dystonia developed in 78% of the patients after a mean duration of 6.8 years from the onset of symptoms. A family history of dystonia was elicited in 17 of the 21 kindreds, accounting for a total of 64 males and one possibly affected female, distributed among 224 individuals in 33 sibships. In 18 of the 33 sibships, 2 or more brothers reportedly had dystonia. There were 12 kindreds with a history of multigenerational dystonia. In those, only males of maternal ancestry were affected, and in 7 of these families, maternal grandfathers reportedly had dystonia. There were no instances of male-to-male transmission. Cytogenetic analysis did not show any X chromosome abnormalities in 4 affected propositi. Several secondary causes of torsion dystonia were excluded, including Wilson disease, aminoacidopathies, organic acidurias, oligosaccharidoses, and chronic hexosaminidase A and B deficiency. These findings substantiate the existence of an X-linked recessive form of primary torsion dystonia. PMID:2368812

Kupke, K G; Lee, L V; Viterbo, G H; Arancillo, J; Donlon, T; Müller, U

1990-06-01

453

Torsional wave experiments with a new magnetostrictive transducer configuration  

NASA Astrophysics Data System (ADS)

For the efficient long-range nondestructive structural health inspection of pipes, guided waves have become widely used. Among the various guided wave modes, the torsional wave is most preferred since its first branch is nondispersive. Our objective in this work is to develop a new magnetostrictive transducer configuration to transmit and receive torsional waves in cylindrical waveguides. The conventional magnetostrictive transducer for the generation and measurement of torsional waves consists of solenoid coils and a nickel strip bonded circumferentially to test pipes. The strip must be premagnetized by a permanent magnet before actual measurements. Because of the premagnetization, the transducer is not suitable for the long-term on-line monitoring of pipes buried underground. To avoid the cumbersome premagnetization and to improve the transduction efficiency, we propose a new transducer configuration using several pieces of nickel strips installed at 45° with respect to the pipe axis. If a static bias magnetic field is also applied, the transducer output can be substantially increased. Several experiments were conducted to study the performance of the proposed transducer configuration. The proposed transducer configuration was also applied for damage detection in an aluminum pipe. .

Kim, Yoon Young; Park, Chan Il; Cho, Seung Hyun; Han, Soon Woo

2005-06-01

454

Dynamical torsion as the microscopic origin of the neutrino seesaw  

NASA Astrophysics Data System (ADS)

It is assumed, that there are two scales in quantum gravity. Metric fluctuates at the scales of the order of the Planck mass. The second scale MT is related to the fluctuations of torsion. We suppose, that it may be as low as MT 1 TeV. Due to the non-minimal coupling to torsion, the attractive interaction between the fermions appear. The non-minimal coupling admits the appearance of different coupling constants for different fermions. This opens the possibility that the interaction with torsion gives the Majorana masses for the right-handed neutrinos (that are assumed to be of the order of MT). We suppose, that the Dirac masses for the neutrino are all close to the mass of electron. This gives the light neutrino masses ?0.25 eV. In addition, the model predicts the appearance of Majorons that may contribute to the dark matter as well as to the invisible decay of the 125 GeV Higgs boson.

Zubkov, M. A.

2014-06-01

455

Development of a torsion balance for adhesion measurements  

NASA Technical Reports Server (NTRS)

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.

Miyoshi, Kazuhisa; Maeda, Chikayoshi; Masuo, Ryuichi

1988-01-01

456

Vacuum static compactified wormholes in eight-dimensional Lovelock theory  

SciTech Connect

In this paper, new exact solutions in eight-dimensional Lovelock theory will be presented. These solutions are the vacuum static wormhole, the black hole, and generalized Bertotti-Robinson space-times with nontrivial torsion. All of the solutions have a cross product structure of the type M{sub 5}x{sigma}{sub 3}, where M{sub 5} is a five-dimensional manifold and {sigma}{sub 3} a compact constant curvature manifold. The wormhole is the first example of a smooth vacuum static Lovelock wormhole which is neither Chern-Simons nor Born-Infeld. It will be also discussed how the presence of torsion affects the 'navigableness' of the wormhole for scalar and spinning particles. It will be shown that the wormhole with torsion may act as 'geometrical filter': A very large torsion may 'increase the traversability' for scalars while acting as a 'polarizator' on spinning particles. This may have interesting phenomenological consequences.

Canfora, Fabrizio [Centro de Estudios Cientificos (CECS), Valdivia (Chile); Giacomini, Alex [Instituto de Fisica, Facultad de Ciencias, Universidad Austral de Chile, Valdivia (Chile); Centro de Estudios Cientificos (CECS), Valdivia (Chile)

2008-10-15

457

Angular momentum in the global atmospheric circulation  

Microsoft Academic Search

Angular momentum is a variable of central importance to the dynamics of the atmosphere both regionally and globally. Moreover, the angular momentum equations yield a precise description of the dynamic interaction of the atmosphere with the oceans and the solid Earth via various torques as exerted by friction, pressure against the mountains and the nonspherical shape of the Earth, and

Joseph Egger; Klaus Weickmann; Klaus-Peter Hoinka

2007-01-01

458

Angular momenta of modeled ocean gyres  

Microsoft Academic Search

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

Greg Holloway; Peter Rhines

1991-01-01

459

Harmonized Profiloplasty Using Balanced Angular Profile Analysis  

Microsoft Academic Search

To evaluate outcomes of aesthetic facial plastic surgery objectively the authors developed a photogrammetric profile analysis method, which they call “balanced angular profile analysis” (BAPA). To develop standards and ways to determine the conformation of various soft tissue segments analytically, 19 mean angular values acquired from the photographs of 71 famous female models (53 Eastern models and 18 Western models)

Heung Sik Park; Seung Chul Rhee; So Ra Kang; Ji Hyuck Lee

2004-01-01

460

Stellar angular diameters from occultation observations.  

NASA Astrophysics Data System (ADS)

This paper reviews the history of measuring stellar angular diameters from lunar occultation observations and the techniques of data analysis. Several effects which can affect the results of measurement are discussed. The author finds that there may be systematic errors in angular diameters measured by various observatories for Aldebaran.

Qian, B.-C.

461

Rotational Energies in Various Torsional Levels of CH_2DOH  

NASA Astrophysics Data System (ADS)

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 lo