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Sample records for additional corotation torque

  1. Linear corotation torques in non-barotropic disks

    SciTech Connect

    Tsang, David

    2014-02-20

    A fully analytic expression for the linear corotation torque to first order in eccentricity for planets in non-barotropic protoplanetary disks is derived, taking into account the effect of disk entropy gradients. This torque formula is applicable to both the co-orbital, corotation torques and the non-co-orbital, corotation torques—for planets in orbits with non-zero eccentricity—in disks where the thermal diffusivity and viscosity are sufficient to maintain the linearity of these interactions. While the co-orbital, corotation torque is important for migration of planets in Type I migration, the non-co-orbital, corotation torque plays an important role in the eccentricity evolution of giant planets that have opened gaps in the disk. The presence of an entropy gradient in the disk can significantly modify the corotation torque in both these cases.

  2. Corotation torques experienced by planets embedded in weakly magnetized turbulent discs

    NASA Astrophysics Data System (ADS)

    Baruteau, C.; Fromang, S.; Nelson, R. P.; Masset, F.

    2011-09-01

    turbulent and laminar viscous discs, and there exists an unsaturated corotation torque in MHD turbulent discs. This analysis also reveals the existence of an additional corotation torque in weakly magnetized discs. Conclusions: Our results of 3D MHD simulations demonstrate the existence of horseshoe dynamics and an unsaturated corotation torque in weakly magnetized discs with fully developed MHD turbulence.

  3. On the corotation torque for low-mass eccentric planets

    NASA Astrophysics Data System (ADS)

    Fendyke, Stephen M.; Nelson, Richard P.

    2014-01-01

    We present the results of high-resolution 2D simulations of low-mass planets on fixed eccentric orbits embedded in protoplanetary discs. The aim of this study is to determine how the strength of the sustained, non-linear corotation torque experienced by embedded planets varies as a function of orbital eccentricity, disc parameters and planetary mass. In agreement with previous work we find that the corotation torque diminishes as orbital eccentricity, e, increases. Analysis of the time-averaged streamlines in the disc demonstrates that the width of the horseshoe region narrows as the eccentricity increases, and we suggest that this narrowing largely explains the observed decrease in the corotation torque. We employ three distinct methods for estimating the strength of the unsaturated corotation torque from our simulations, and provide an empirical fit to these results. We find that a simple model where the corotation torque, ΓC, decreases exponentially with increasing eccentricity [i.e. ΓC ∝ exp (-e/ef)] provides a good global fit to the data with an e-folding eccentricity, ef, that scales linearly with the disc scale height at the planet location. We confirm that this model provides a good fit for planet masses of 5 and 10 M⊕ in our simulations. The formation of planetary systems is likely to involve significant planet-planet interactions that will excite eccentric orbits, and this is likely to influence disc-driven planetary migration through modification of the corotation torque. Our results suggest that high fidelity models of planetary formation should account for these effects.

  4. Corotating shock structures

    NASA Technical Reports Server (NTRS)

    Ogilvie, K. W.

    1972-01-01

    Consideration of observed interplanetary shocks leads to the conclusion that a corotating forward shock has not been unambiguously identified at 1 AU. A reverse shock identified in September 1967 is a likely candidate for a corotating structure.

  5. Monitoring a high-amplitude δ Scuti star for 152 days: discovery of 12 additional modes and modulation effects in the light curve of CoRoT 101155310

    NASA Astrophysics Data System (ADS)

    Poretti, E.; Rainer, M.; Weiss, W. W.; Bognár, Zs.; Moya, A.; Niemczura, E.; Suárez, J. C.; Auvergne, M.; Baglin, A.; Baudin, F.; Benkő, J. M.; Debosscher, J.; Garrido, R.; Mantegazza, L.; Paparó, M.

    2011-04-01

    Aims: The detection of small-amplitude nonradial modes in high-amplitude δ Sct (HADS) variables has been very elusive until at least five of them were detected in the light curve of V974 Oph obtained from ground-based observations. The combination of radial and nonradial modes has a high asteroseismic potential, thanks to the strong constraints we can put in the modelling. The continuous monitoring of ASAS 192647-0030.0 ≡ CoRoT 101155310 (P = 0.1258 d, V = 13.4) ensured from space by the CoRoT (COnvection, ROtation and planetary Transits) mission constitutes a unique opportunity to exploit such potential. Methods: The 22270 CoRoT measurements were performed in the chromatic mode. They span 152 d and cover 1208 consecutive cycles. After the correction for one jump and the long-term drift, the level of the noise turned out to be 29 μmag. The phase shifts and amplitude ratios of the coloured CoRoT data, the HARPS spectra, and the period-luminosity relation were used to determine a self-consistent physical model. In turn, it allowed us to model the oscillation spectrum, also giving feedback on the internal structure of the star. Results: In addition to the fundamental radial mode f1 = 7.949 d-1 with harmonics up to 10f1, we detected 12 independent terms. Linear combinations were also found and the light curve was solved by means of 61 frequencies (smallest amplitude 0.10 mmag). The newest result is the detection of a periodic modulation of the f1 mode (triplets at ± 0.193 d-1 centred on f1 and 2f1), discussed as a rotational effect or as an extension of the Blazhko effect to HADS stars. The physical model suggests that CoRoT 101155310 is an evolved star, with a slight subsolar metallic abundance, close to the terminal age main sequence. All the 12 additional terms are identified with mixed modes in the predicted overstable region. The CoRoT space mission was developed and is operated by the French space agency CNES, with the participation of ESA's RSSD and Science

  6. Displaceable Gear Torque Controlled Driver

    NASA Technical Reports Server (NTRS)

    Cook, Joseph S., Jr. (Inventor)

    1997-01-01

    Methods and apparatus are provided for a torque driver including a displaceable gear to limit torque transfer to a fastener at a precisely controlled torque limit. A biasing assembly biases a first gear into engagement with a second gear for torque transfer between the first and second gear. The biasing assembly includes a pressurized cylinder controlled at a constant pressure that corresponds to a torque limit. A calibrated gage and valve is used to set the desired torque limit. One or more coiled output linkages connect the first gear with the fastener adaptor which may be a socket for a nut. A gear tooth profile provides a separation force that overcomes the bias to limit torque at the desired torque limit. Multiple fasteners may be rotated simultaneously to a desired torque limit if additional output spur gears are provided. The torque limit is adjustable and may be different for fasteners within the same fastener configuration.

  7. COROT telescope development

    NASA Astrophysics Data System (ADS)

    Viard, Thierry; Bodin, Pierre; Magnan, Alain

    2004-06-01

    COROTEL is the telescope of the future COROT satellite which aims at measuring stellar flux variations very accurately. To perform this mission, COROTEL has to be very well protected against straylight (from Sun and Earth) and must be very stable with time. Thanks to its high experience in this field, Alcatel Space has proposed an original optical concept associated with a high performance baffle. From 2001, the LAM (Laboratoire d'Astrophysique de Marseille, CNRS) has placed the telescope development contract to Alcatel Space and is presently almost finished. Based on relevant material and efficient thermal control design, COROTEL should meet its ambitious performance and bring to scientific community for the first time precious data coming from stars and their possible companions.

  8. Torque sensor

    NASA Astrophysics Data System (ADS)

    Fgeppert, E.

    1984-09-01

    Mechanical means for sensing turning torque generated by the load forces in a rotary drive system is described. The sensing means is designed to operate with minimal effect on normal operation of the drive system. The invention can be employed in various drive systems, e.g., automotive engine-transmission power plants, electric motor-operated tools, and metal cutting machines. In such drive systems, the torque-sensing feature may be useful for actuation of various control devices, such as electric switches, mechanical clutches, brake actuators, fluid control valves, or audible alarms. The torque-sensing function can be used for safety overload relief, motor de-energization, engine fuel control transmission clutch actuation, remote alarm signal, tool breakage signal, etc.

  9. Revisiting the Corotation Electric Field

    NASA Astrophysics Data System (ADS)

    Rothwell, P. L.

    2001-05-01

    The rotation of the Earth's dipole magnetic field produces a corotation electric field in the nonrotating frame of reference. A quick calculation implies that this field might arise from the relative motion of an observer in the nonrotating frame and the motion of rotating magnetic field lines. However, upon applying Faraday's Law one finds that total time rate of change of the magnetic field as seen in the nonrotating frame is zero due to the azimuthal symmetry of the dipole. Therefore, classical EM theory(1) predicts a zero corotation electric field in the nonrotating frame for a vacuum. This conundrum has been traditionally treated in the following manner(2,3). 1) Start with a vacuum state with no conductors and plasma present. The transformation between E (the electric field in the nonrotating frame) and E' (the electric field in the rotating frame)implies that in the rotating frame E' is nonzero while E = 0. 2) In the presence of a thin conducting spherical shell (the ionosphere) polarization charges form in the shell due to the magnetic force on the electrons. A polarization electric field Ep is created such that in the idealized case the shell has a uniform electric potential. This Ep has a component along the magnetic field lines outside the shell. 3) Plasma will polarize along B, thus canceling the parallel component of Ep which allows the potential on the shell to be mapped along the magnetic field lines setting E' = 0. From the transformation equation E is now nonzero. This is the electric field required in the nonrotating frame for the plasma to corotate with the dipole. The presence of the corotation electric field is not a local result, but a nonlocal effect that requires the presence of an ionosphere and a conducting plasma. (1) W.K.H. Panofsky and M. Phillips, Classical Electricity and Magnetism, Addison-Wesley, 1956. (2) H. Alfven and C.-G. Falthammar, Cosmical Electrodynamics, 2nd ed., Oxford Press, 1963. (3) E.W.Hones and J.E.Bergeson, J. Geophys

  10. The composition of corotating energetic particle streams

    NASA Technical Reports Server (NTRS)

    Mcguire, R. E.; Von Renvinge, T. T.; Mcdonald, F. B.

    1978-01-01

    The relative abundances of 1.5 to 23 MeV/nucleon ions in corotating nucleon streams were compared with ion abundances in particle events associated with solar flares and with solar and solar wind abundances. He/O and C/O ratios were found to be a factor of the order two to three times greater in corotating streams than in flare associated events. The distribution of H/He ratios in corotating streams was found to be much narrower and of lower average value than in flare associated events. H/He in corotating energetic particle streams compared favorably both in lack of variability and numerical value to H/He in high speed solar wind plasma streams. This comparison suggested that the source population for the corotating energetic particles was the solar wind.

  11. Torque control for electric motors

    NASA Technical Reports Server (NTRS)

    Bernard, C. A.

    1980-01-01

    Method for adjusting electric-motor torque output to accomodate various loads utilizes phase-lock loop to control relay connected to starting circuit. As load is imposed, motor slows down, and phase lock is lost. Phase-lock signal triggers relay to power starting coil and generate additional torque. Once phase lock is recoverd, relay restores starting circuit to its normal operating mode.

  12. On the width and shape of the corotation region for low-mass planets

    NASA Astrophysics Data System (ADS)

    Paardekooper, S.-J.; Papaloizou, J. C. B.

    2009-04-01

    We study the coorbital flow for embedded, low-mass planets. We provide a simple semi-analytic model for the corotation region, which is subsequently compared to high-resolution numerical simulations. The model is used to derive an expression for the half-width of the horseshoe region, xs, which in the limit of zero softening is given by xs/rp = 1.68(q/h)1/2, where q is the planet to central star mass ratio, h is the disc aspect ratio and rp is the orbital radius. This is in very good agreement with the same quantity measured from simulations. This result is used to show that horseshoe drag is about an order of magnitude larger than the linear corotation torque in the zero-softening limit. Thus, the horseshoe drag, the sign of which depends on the gradient of specific vorticity, is important for estimates of the total torque acting on the planet. We further show that phenomena, such as the Lindblad wakes, with a radial separation from corotation of approximately a pressure scaleheight H can affect xs, even though for low-mass planets xs << H. The effect is to distort streamlines and reduce xs through the action of a back pressure. This effect is reduced for smaller gravitational softening parameters and planets of higher mass, for which xs becomes comparable to H.

  13. Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system

    NASA Astrophysics Data System (ADS)

    Haywood, R. D.; Cameron, A. C.; Queloz, D.; Barros, S. C. C.; Deleuil, M.; Fares, R.; Gillon, M.; Hatzes, A.; Lanza, A. F.; Lovis, C.; Moutou, C.; Pepe, F.; Pollacco, D.; Santerne, A.; Ségransan, D.; Unruh, Y.

    2014-01-01

    Since the discovery of the transiting Super-Earth CoRoT-7b, several investigations have been made of the number and precise masses of planets present in the system, but they all yield different results, owing to the star's high level of activity. Radial velocity (RV) variations induced by stellar activity therefore need to be modelled and removed to allow a reliable detection of all planets in the system. We re-observed CoRoT-7 in January 2012 with both HARPS and the CoRoT satellite, so that we now have the benefit of simultaneous RV and photometric data. We fitted the off-transit variations in the CoRoT lightcurve using a harmonic decomposition similar to that implemented in Queloz et al. (2009). This fit was then used to model the stellar RV contribution, according to the methods described by Aigrain et al. (2011). This model was incorporated into a Monte Carlo Markov Chain in order to make a precise determination of the orbits of CoRoT-7b and CoRoT-7c. We also assess the evidence for the presence of one or two additional planetary companions.

  14. Warm Spitzer Photometry of the Transiting Exoplanets CoRoT-1 and CoRoT-2 at Secondary Eclipse

    NASA Astrophysics Data System (ADS)

    Deming, Drake; Knutson, Heather; Agol, Eric; Desert, Jean-Michel; Burrows, Adam; Fortney, Jonathan J.; Charbonneau, David; Cowan, Nicolas B.; Laughlin, Gregory; Langton, Jonathan; Showman, Adam P.; Lewis, Nikole K.

    2011-01-01

    We measure secondary eclipses of the hot giant exoplanets CoRoT-1 at 3.6 and 4.5 μm, and CoRoT-2 at 3.6 μm, both using Warm Spitzer. We find that the Warm Spitzer mission is working very well for exoplanet science. For consistency of our analysis we also re-analyze archival cryogenic Spitzer data for secondary eclipses of CoRoT-2 at 4.5 and 8 μm. We compare the total data for both planets, including optical eclipse measurements by the CoRoT mission, and ground-based eclipse measurements at 2 μm, to existing models. Both planets exhibit stronger eclipses at 4.5 than at 3.6 μm, which is often indicative of an atmospheric temperature inversion. The spectrum of CoRoT-1 is best reproduced by a 2460 K blackbody, due either to a high altitude layer that strongly absorbs stellar irradiance, or an isothermal region in the planetary atmosphere. The spectrum of CoRoT-2 is unusual because the 8 μm contrast is anomalously low. Non-inverted atmospheres could potentially produce the CoRoT-2 spectrum if the planet exhibits line emission from CO at 4.5 μm, caused by tidal-induced mass loss. However, the viability of that hypothesis is questionable because the emitting region cannot be more than about 30% larger than the planet's transit radius, based on the ingress and egress times at eclipse. An alternative possibility to account for the spectrum of CoRoT-2 is an additional opacity source that acts strongly at wavelengths less than 5 μm, heating the upper atmosphere while allowing the deeper atmosphere seen at 8 μm to remain cooler. We obtain a similar result as Gillon et al. for the phase of the secondary eclipse of CoRoT-2, implying an eccentric orbit with e cos(ω) = -0.0030 ± 0.0004.

  15. WARM SPITZER PHOTOMETRY OF THE TRANSITING EXOPLANETS CoRoT-1 AND CoRoT-2 AT SECONDARY ECLIPSE

    SciTech Connect

    Deming, Drake; Knutson, Heather; Agol, Eric; Cowan, Nicolas B.; Desert, Jean-Michel; Charbonneau, David; Burrows, Adam; Fortney, Jonathan J.; Laughlin, Gregory; Langton, Jonathan; Showman, Adam P.; Lewis, Nikole K.

    2011-01-10

    We measure secondary eclipses of the hot giant exoplanets CoRoT-1 at 3.6 and 4.5 {mu}m, and CoRoT-2 at 3.6 {mu}m, both using Warm Spitzer. We find that the Warm Spitzer mission is working very well for exoplanet science. For consistency of our analysis we also re-analyze archival cryogenic Spitzer data for secondary eclipses of CoRoT-2 at 4.5 and 8 {mu}m. We compare the total data for both planets, including optical eclipse measurements by the CoRoT mission, and ground-based eclipse measurements at 2 {mu}m, to existing models. Both planets exhibit stronger eclipses at 4.5 than at 3.6 {mu}m, which is often indicative of an atmospheric temperature inversion. The spectrum of CoRoT-1 is best reproduced by a 2460 K blackbody, due either to a high altitude layer that strongly absorbs stellar irradiance, or an isothermal region in the planetary atmosphere. The spectrum of CoRoT-2 is unusual because the 8 {mu}m contrast is anomalously low. Non-inverted atmospheres could potentially produce the CoRoT-2 spectrum if the planet exhibits line emission from CO at 4.5 {mu}m, caused by tidal-induced mass loss. However, the viability of that hypothesis is questionable because the emitting region cannot be more than about 30% larger than the planet's transit radius, based on the ingress and egress times at eclipse. An alternative possibility to account for the spectrum of CoRoT-2 is an additional opacity source that acts strongly at wavelengths less than 5 {mu}m, heating the upper atmosphere while allowing the deeper atmosphere seen at 8 {mu}m to remain cooler. We obtain a similar result as Gillon et al. for the phase of the secondary eclipse of CoRoT-2, implying an eccentric orbit with e cos({omega}) = -0.0030 {+-} 0.0004.

  16. MHD simulations: Corotating Interaction Regions

    NASA Astrophysics Data System (ADS)

    Wiengarten, T.; Kleimann, J.; Fichtner, H.; Kühl, P.; Heber, B.; Kissmann, R.

    2013-12-01

    Corotating Interaction Regions (CIRs) form in the solar wind when parcels of fast-speed wind interact with slow-speed wind due to the rotation of the Sun. The resulting buildup of pressure generates disturbances that, with increasing time (or distance from the Sun), may develop into a so-called forward-reverse shock-pair. During solar-quiet times CIRs can be the dominant force shaping large-scale structures in the heliosphere. Studying CIRs is therefore important because the associated shocks are capable of e.g. accelerating energetic particles or deflecting cosmic rays. The global structure of CIRs can be modeled with an MHD approach that gives the plasma quantities needed to model the transport of particles in the heliosphere (with e.g. stochastic differential equations (SDEs)). Our MHD code CRONOS employs a semi-discrete finite volume scheme with adaptive time-stepping Runge-Kutta integration. The solenoidality of the magnetic field is ensured via constrained transport and the code supports Cartesian, Cylindrical and Spherical coordinates (including coordinate singularities) with the option for non-equidistant grids. The code runs in parallel (MPI) and supports the HDF5 output data format. Here, we show results from 3D-MHD simulations with our code CRONOS for a) analytic boundary conditions where results can be compared to those obtained with a different code and b) boundary conditions derived with the Wang-Sheeley-Arge model from observational data (WSO), which are compared to spacecraft observations. Comparison with Pizzo (1982) for analytic boundary conditions Comparison with STEREO A for Carrington Rotation 2060

  17. Hex ball torque test

    NASA Technical Reports Server (NTRS)

    Robinson, B. A.; Foster, C. L.

    1986-01-01

    A series of torque tests were performed on four flight-type hex ball universal joints in order to characterize and determine the actual load-carrying capability of this device. The universal joint is a part of manual actuation rods for scientific instruments within the Hubble Space Telescope. It was found that the hex ball will bind slightly during the initial load application. This binding did not affect the function of the universal joint, and the units would wear-in after a few additional loading cycles. The torsional yield load was approximately 50 ft-lb, and was consistent among the four test specimens. Also, the torque required to cause complete failure exceeded 80 ft-lb. It is concluded that the hex ball universal joint is suitable for its intended applications.

  18. Torque measurement issues

    NASA Astrophysics Data System (ADS)

    Goszczak, J.

    2016-09-01

    Problems with torque measurement in operational tests are considered. Introduction with torque definition is included. Short overview of different types of torque meters is presented. Own results and remarks about torque measurement and torque meters are quoted. Author takes into account such problems as: electromagnetic and mechanical noise (from componentry, e.g. clutches). Different ways of averaging and their results are discussed. Conclusions based on test results are included in the summary.

  19. Gravitational torques imply molecular gas inflow towards the nucleus of M 51

    NASA Astrophysics Data System (ADS)

    Querejeta, M.; Meidt, S. E.; Schinnerer, E.; García-Burillo, S.; Dobbs, C. L.; Colombo, D.; Dumas, G.; Hughes, A.; Kramer, C.; Leroy, A. K.; Pety, J.; Schuster, K. F.; Thompson, T. A.

    2016-04-01

    The transport of gas towards the centre of galaxies is critical for black hole feeding and, indirectly, it can control active galactic nucleus (AGN) feedback. We have quantified the molecular gas inflow in the central R< 1 kpc of M 51 to be 1 M⊙/yr, using a new gravitational torque map and the molecular gas traced by the Plateau de Bure Interferometer Arcsecond Whirlpool Survey (PAWS). The nuclear stellar bar is responsible for this gas inflow. We also used torque profiles to estimate the location of dynamical resonances, and the results suggest a corotation for the bar CRbar ~ 20'', and a corotation for the spiral CRsp ~ 100''. We demonstrate how important it is to correct 3.6 μm images for dust emission when gravitational torques are to be computed, and we examine further sources of uncertainty. Our observational measurement of gas inflow can be compared with nuclear molecular outflow rates and provide useful constraints for numerical simulations.

  20. Chaotic dynamics of corotating magnetospheric convection

    NASA Technical Reports Server (NTRS)

    Summers, Danny; Mu, Jian-Lin

    1994-01-01

    The corotating plasma convection system of the Jovian magnetosphere is analyzed. The macroscopic (mhd) model introduced by Summers and Mu, (1992) that incorporates the effects of microdiffusion is extended by including previously neglected density effects. We reduce the governing partial differential equations to a third-order ordinary differential system by the Galerkin technique of mode truncation. We carry out such a severe truncation partly in the interests of tractability, and leave open the question of the efficacy of adding additional modes. Exhaustive numerical integrations are carried out to calculate the long-term solutions, and we discover that a rich array of plasma motions is possible, dependent on the value of the height-integrated ionospheric Pederson conductivity Sigma. If Sigma is less than a certain critical value Sigma(sub c), then plasma motion can be expected to be chaotic (or periodic), while if Sigma is greater than Sigma(sub c), then steady state convection is expected. In the former case, whether the plasma motion is chaotic or periodic (and, if periodic, the magnitude of the period) can be very sensitive to the value of Sigma. The value of Sigma(sub c), which is a function of a parameter q that occurs in the assumed form of the stationary radial profile (varies as L(exp -q) of the plasma mass per unit magnetic flux, lies well within the accepted range of values of Sigma for Jupiter, i.e. Sigma greater than or equal to 0.1 mho and less than or equal to 10 mho.

  1. Planets and stellar activity: hide and seek in the CoRoT-7 system

    NASA Astrophysics Data System (ADS)

    Haywood, R. D.; Collier Cameron, A.; Queloz, D.; Barros, S. C. C.; Deleuil, M.; Fares, R.; Gillon, M.; Lanza, A. F.; Lovis, C.; Moutou, C.; Pepe, F.; Pollacco, D.; Santerne, A.; Ségransan, D.; Unruh, Y. C.

    2014-09-01

    Since the discovery of the transiting super-Earth CoRoT-7b, several investigations have yielded different results for the number and masses of planets present in the system, mainly owing to the star's high level of activity. We re-observed CoRoT-7 in 2012 January with both HARPS and CoRoT, so that we now have the benefit of simultaneous radial-velocity and photometric data. This allows us to use the off-transit variations in the star's light curve to estimate the radial-velocity variations induced by the suppression of convective blueshift and the flux blocked by starspots. To account for activity-related effects in the radial velocities which do not have a photometric signature, we also include an additional activity term in the radial-velocity model, which we treat as a Gaussian process with the same covariance properties (and hence the same frequency structure) as the light curve. Our model was incorporated into a Monte Carlo Markov Chain in order to make a precise determination of the orbits of CoRoT-7b and CoRoT-7c. We measure the masses of planets b and c to be 4.73 ± 0.95 and 13.56 ± 1.08 M⊕, respectively. The density of CoRoT-7b is (6.61 ± 1.72)(Rp/1.58 R⊕)-3 g cm-3, which is compatible with a rocky composition. We search for evidence of an additional planet d, identified by previous authors with a period close to 9 d. We are not able to confirm the existence of a planet with this orbital period, which is close to the second harmonic of the stellar rotation at ˜7.9 d. Using Bayesian model selection, we find that a model with two planets plus activity-induced variations is most favoured.

  2. Active motion assisted by correlated stochastic torques.

    PubMed

    Weber, Christian; Radtke, Paul K; Schimansky-Geier, Lutz; Hänggi, Peter

    2011-07-01

    The stochastic dynamics of an active particle undergoing a constant speed and additionally driven by an overall fluctuating torque is investigated. The random torque forces are expressed by a stochastic differential equation for the angular dynamics of the particle determining the orientation of motion. In addition to a constant torque, the particle is supplemented by random torques, which are modeled as an Ornstein-Uhlenbeck process with given correlation time τ(c). These nonvanishing correlations cause a persistence of the particles' trajectories and a change of the effective spatial diffusion coefficient. We discuss the mean square displacement as a function of the correlation time and the noise intensity and detect a nonmonotonic dependence of the effective diffusion coefficient with respect to both correlation time and noise strength. A maximal diffusion behavior is obtained if the correlated angular noise straightens the curved trajectories, interrupted by small pirouettes, whereby the correlated noise amplifies a straightening of the curved trajectories caused by the constant torque.

  3. Spectral characterization and differential rotation study of active CoRoT stars

    NASA Astrophysics Data System (ADS)

    Nagel, E.; Czesla, S.; Schmitt, J. H. M. M.

    2016-05-01

    The CoRoT space telescope observed nearly 160 000 light curves. Among the most outstanding is that of the young, active planet host star CoRoT-2A. In addition to deep planetary transits, the light curve of CoRoT-2A shows strong rotational variability and a superimposed beating pattern. To study the stars that produce such an intriguing pattern of photometric variability, we identified a sample of eight stars with rotation periods between 0.8 and 11 days and photometric variability amplitudes of up to 7.5%, showing a similar CoRoT light curve. We also obtained high-resolution follow-up spectroscopy with TNG/SARG and carried out a spectral analysis with SME and MOOG. We find that the color dependence of the light curves is consistent with rotational modulation due to starspots and that latitudinal differential rotation provides a viable explanation for the light curves, although starspot evolution is also expected to play an important role. Our MOOG and SME spectral analyses provide consistent results, showing that the targets are dwarf stars with spectral types between F and mid-K. Detectable Li i absorption in four of the targets confirms a low age of 100-400 Myr also deduced from gyrochronology. Our study indicates that the photometric beating phenomenon is likely attributable to differential rotation in fast-rotating stars with outer convection zones.

  4. Additives

    NASA Technical Reports Server (NTRS)

    Smalheer, C. V.

    1973-01-01

    The chemistry of lubricant additives is discussed to show what the additives are chemically and what functions they perform in the lubrication of various kinds of equipment. Current theories regarding the mode of action of lubricant additives are presented. The additive groups discussed include the following: (1) detergents and dispersants, (2) corrosion inhibitors, (3) antioxidants, (4) viscosity index improvers, (5) pour point depressants, and (6) antifouling agents.

  5. Angular Acceleration without Torque?

    ERIC Educational Resources Information Center

    Kaufman, Richard D.

    2012-01-01

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

  6. Evidence for Corotating Convection in Saturn's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Kivelson, M. G.; Southwood, D. J.; Dougherty, M. K.

    2006-05-01

    Saturn's magnetic field exhibits a high degree of azimuthal symmetry, yet the field and plasma signatures of the magnetosphere are modulated at a period close to that of planetary rotation. How, then, is a clear periodicity imposed on the magnetic field and plasma of the planetary magnetosphere? In this talk, Cassini magnetometer data are used to develop a scenario for the dynamics of the Saturn magnetosphere. The proposal is that mass transport, accomplished in the inner magnetosphere by interchange motion, feeds into the outer magnetosphere where ballooning driven by centrifugal stress leads to outward transport, field reconnection and plasma loss in a favored local time sector; flux is transported inward in other regions. The model is closely related to the concept of corotating convection proposed by Dessler, Hill, and co-workers for Jupiter. The proposed mechanism can be consistent with aspects of the empirical camshaft model introduced by Espinosa et al., 2003 to explain Pioneer and Voyager magnetometer data. Anomalous transport here proposed could originate from a localized ionospheric conductivity anomaly. The resulting cyclic stress modulates the current in the current sheet and can account for its north-south excursions. The convection patterns proposed also imply that corotating, field-aligned currents would be a basic feature of the Saturn system.

  7. Merging of co-rotating trailing vortices

    NASA Astrophysics Data System (ADS)

    Cerretelli, C.; Leweke, T.; Williamson, C. H. K.

    1999-11-01

    The merging of co-rotating vortices is an important physical phenomenon in aerodynamics as well as in fundamental turbulent flows. Merging plays a role in the aerodynamics of airplane wing wakes, where it can accelerate the development of the Crow instability (Crouch 1997). Although vortex merger has been extensively studied, most numerical investigations concern the case of the two dimensional inviscid interactions. On the other hand, the dynamics of three dimensional viscous vortices, which spin around each other in an helical path, is not yet fully understood, and this is the focus of the present experimental investigation. Previous work by Chen, Jacob and Savas (1999) shows that merging of co-rotating vortices, from a flapped wing, occurs at approximately 0.8 of an orbit period after formation, independently of the circulation Reynolds number Re_Γ. In the present work, merging is studied by using a biplane wing system, as well as the DPIV technique. In our investigation, we find that the time taken for merging, measured in orbit periods, is a function not only of the experimental geometry, but is also a function of the circulation Reynolds number.

  8. The CoRoT-7 planetary system: two orbiting super-Earths

    NASA Astrophysics Data System (ADS)

    Queloz, D.; Bouchy, F.; Moutou, C.; Hatzes, A.; Hébrard, G.; Alonso, R.; Auvergne, M.; Baglin, A.; Barbieri, M.; Barge, P.; Benz, W.; Bordé, P.; Deeg, H. J.; Deleuil, M.; Dvorak, R.; Erikson, A.; Ferraz Mello, S.; Fridlund, M.; Gandolfi, D.; Gillon, M.; Guenther, E.; Guillot, T.; Jorda, L.; Hartmann, M.; Lammer, H.; Léger, A.; Llebaria, A.; Lovis, C.; Magain, P.; Mayor, M.; Mazeh, T.; Ollivier, M.; Pätzold, M.; Pepe, F.; Rauer, H.; Rouan, D.; Schneider, J.; Segransan, D.; Udry, S.; Wuchterl, G.

    2009-10-01

    We report on an intensive observational campaign carried out with HARPS at the 3.6 m telescope at La Silla on the star CoRoT-7. Additional simultaneous photometric measurements carried out with the Euler Swiss telescope have demonstrated that the observed radial velocity variations are dominated by rotational modulation from cool spots on the stellar surface. Several approaches were used to extract the radial velocity signal of the planet(s) from the stellar activity signal. First, a simple pre-whitening procedure was employed to find and subsequently remove periodic signals from the complex frequency structure of the radial velocity data. The dominant frequency in the power spectrum was found at 23 days, which corresponds to the rotation period of CoRoT-7. The 0.8535 day period of CoRoT-7b planetary candidate was detected with an amplitude of 3.3 m s-1. Most other frequencies, some with amplitudes larger than the CoRoT-7b signal, are most likely associated with activity. A second approach used harmonic decomposition of the rotational period and up to the first three harmonics to filter out the activity signal from radial velocity variations caused by orbiting planets. After correcting the radial velocity data for activity, two periodic signals are detected: the CoRoT-7b transit period and a second one with a period of 3.69 days and an amplitude of 4 m s-1. This second signal was also found in the pre-whitening analysis. We attribute the second signal to a second, more remote planet CoRoT-7c . The orbital solution of both planets is compatible with circular orbits. The mass of CoRoT-7b is 4.8±0.8 (M⊕) and that of CoRoT-7c is 8.4± 0.9 (M⊕), assuming both planets are on coplanar orbits. We also investigated the false positive scenario of a blend by a faint stellar binary, and this may be rejected by the stability of the bisector on a nightly scale. According to their masses both planets belong to the super-Earth planet category. The average density of CoRoT-7b

  9. Planetary transit candidates in Corot-IRa01 field

    NASA Astrophysics Data System (ADS)

    Carpano, S.; Cabrera, J.; Alonso, R.; Barge, P.; Aigrain, S.; Almenara, J.-M.; Bordé, P.; Bouchy, F.; Carone, L.; Deeg, H. J.; de La Reza, R.; Deleuil, M.; Dvorak, R.; Erikson, A.; Fressin, F.; Fridlund, M.; Gondoin, P.; Guillot, T.; Hatzes, A.; Jorda, L.; Lammer, H.; Léger, A.; Llebaria, A.; Magain, P.; Moutou, C.; Ofir, A.; Ollivier, M.; Janot-Pacheco, E.; Pätzold, M.; Pont, F.; Queloz, D.; Rauer, H.; Régulo, C.; Renner, S.; Rouan, D.; Samuel, B.; Schneider, J.; Wuchterl, G.

    2009-10-01

    Context: CoRoT is a pioneering space mission devoted to the analysis of stellar variability and the photometric detection of extrasolar planets. Aims: We present the list of planetary transit candidates detected in the first field observed by CoRoT, IRa01, the initial run toward the Galactic anticenter, which lasted for 60 days. Methods: We analysed 3898 sources in the coloured bands and 5974 in the monochromatic band. Instrumental noise and stellar variability were taken into account using detrending tools before applying various transit search algorithms. Results: Fifty sources were classified as planetary transit candidates and the most reliable 40 detections were declared targets for follow-up ground-based observations. Two of these targets have so far been confirmed as planets, CoRoT-1b and CoRoT-4b, for which a complete characterization and specific studies were performed. The CoRoT space mission, launched on December 27th 2006, has been developed and is operated by CNES, with contributions from Austria, Belgium, Brazil, ESA, Germany, and Spain. Four French laboratories associated with the CNRS (LESIA, LAM, IAS ,OMP) collaborate with CNES on the satellite development. First CoRoT data are available to the public from the CoRoT archive: http://idoc-corot.ias.u-psud.fr.

  10. Displaceable Spur Gear Torque Controlled Driver and Method

    NASA Technical Reports Server (NTRS)

    Cook, Joseph S., Jr. (Inventor)

    1996-01-01

    Methods and apparatus are provided for a torque driver including a laterally displaceable gear support member to carry an output spur gear. A biasing assembly biases the output spur gear into engagement with a pinion to which is applied an input torque greater than a desired output torque limit for a threaded fastener such as a nut or screw. A coiled output linkage connects the output spur gear with a fastener adaptor which may be a socket for a nut. A gear tooth profile provides a separation force that overcomes the bias to limit torque at the desired torque limit. Multiple fasteners may be rotated simultaneously to a desired torque limit if additional output spur gears are provided. A gauged selector mechanism is provided to laterally displace multiple driven members for fasteners arranged in differing configurations. The torque limit is selectably adjustable and may be different for fasteners within the same fastener configuration.

  11. Displaceable spur gear torque controlled driver and method

    NASA Technical Reports Server (NTRS)

    Cook, Joseph S., Jr. (Inventor)

    1994-01-01

    Methods and apparatus are provided for a torque driver including a laterally displaceable gear support member to carry an output spur gear. A biasing assembly biases the output spur gear into engagement with a pinion to which is applied an input torque greater than a desired output torque limit for a threaded fastener such as a nut or screw. A coiled output linkage connects the output spur gear with a fastener adaptor which may be a socket for a nut. A gear tooth profile provides a separation force that overcomes the bias to limit torque at the desired torque limit. Multiple fasteners may be rotated simultaneously to a desired torque limit if additional output spur gears are provided. A gauged selector mechanism is provided to laterally displace multiple driver members for fasteners arranged in differing configurations. The torque limit is selectably adjustable and may be different for fasteners within the same fastener configuration.

  12. Fabricated torque shaft

    DOEpatents

    Mashey, Thomas Charles

    2002-01-01

    A fabricated torque shaft is provided that features a bolt-together design to allow vane schedule revisions with minimal hardware cost. The bolt-together design further facilitates on-site vane schedule revisions with parts that are comparatively small. The fabricated torque shaft also accommodates stage schedules that are different one from another in non-linear inter-relationships as well as non-linear schedules for a particular stage of vanes.

  13. Time-dependent Corotation Resonance in Barred Galaxies

    NASA Astrophysics Data System (ADS)

    Wu, Yu-Ting; Pfenniger, Daniel; Taam, Ronald E.

    2016-10-01

    The effective potential neighboring the corotation resonance region in barred galaxies is shown to be strongly time-dependent in any rotating frame, due to the competition of nearby perturbations of similar strengths with differing rotation speeds. Contrary to the generally adopted assumption that in the bar rotating frame the corotation region should possess four stationary equilibrium points (Lagrange points), with high quality N-body simulations, we localize the instantaneous equilibrium points (EPs) and find that they circulate or oscillate broadly in azimuth with respect to the pattern speeds of the inner or outer perturbations. This implies that at the particle level the Jacobi integral is not well conserved around the corotation radius. That is, angular momentum exchanges decouple from energy exchanges, enhancing the chaotic diffusion of stars through the corotation region.

  14. Corotation Lag in Jupiter's Magnetosphere: Comparison of Observation and Theory.

    PubMed

    Hill, T W

    1980-01-18

    Voyager 1 plasma flow data are compared with a recent theory that predicted measurable departures from rigid corotation in Jupiter's magnetosphere as a consequence of rapid plasma production and weak atmosphere-magnetosphere coupling. The comparison indicates that the theory can account for the observed corotation lag, provided that the plasma mass production rate during the Voyager 1 encounter was rather larger than expected, namely approximately 10(30) atomic mass units per second.

  15. Knudsen torque on heated micro beams

    NASA Astrophysics Data System (ADS)

    Li, Qi; Liang, Tengfei; Ye, Wenjing

    2014-12-01

    Thermally induced mechanical loading has been shown to have significant effects on micro/nano objects immersed in a gas with a non-uniform temperature field. While the majority of existing studies and related applications focus on forces, we investigate the torque, and thus the rotational motion, produced by such a mechanism. Using the asymptotic analysis in the near continuum regime, the Knudsen torque acting on an asymmetrically located uniformly heated microbeam in a cold enclosure is investigated. The existence of a non-zero net torque is demonstrated. In addition, it has been found that by manipulating the system configuration, the rotational direction of the torque can be changed. Two types of rotational motion of the microbeam have been identified: the pendulum motion of a rectangular beam, and the unidirectional rotation of a cylindrical beam. A rotational frequency of 4 rpm can be achieved for the cylindrical beam with a diameter of 3μm at Kn = 0.005. Illustrated by the simulations using the direct simulation of Monte Carlo, the Knudsen torque can be much increased in the transition regime, demonstrating the potential of Knudsen torque serving as a rotation engine for micro/nano objects.

  16. Knudsen torque on heated micro beams

    SciTech Connect

    Li, Qi; Liang, Tengfei; Ye, Wenjing

    2014-12-09

    Thermally induced mechanical loading has been shown to have significant effects on micro/nano objects immersed in a gas with a non-uniform temperature field. While the majority of existing studies and related applications focus on forces, we investigate the torque, and thus the rotational motion, produced by such a mechanism. Using the asymptotic analysis in the near continuum regime, the Knudsen torque acting on an asymmetrically located uniformly heated microbeam in a cold enclosure is investigated. The existence of a non-zero net torque is demonstrated. In addition, it has been found that by manipulating the system configuration, the rotational direction of the torque can be changed. Two types of rotational motion of the microbeam have been identified: the pendulum motion of a rectangular beam, and the unidirectional rotation of a cylindrical beam. A rotational frequency of 4 rpm can be achieved for the cylindrical beam with a diameter of 3μm at Kn = 0.005. Illustrated by the simulations using the direct simulation of Monte Carlo, the Knudsen torque can be much increased in the transition regime, demonstrating the potential of Knudsen torque serving as a rotation engine for micro/nano objects.

  17. SATURATED TORQUE FORMULA FOR PLANETARY MIGRATION IN VISCOUS DISKS WITH THERMAL DIFFUSION: RECIPE FOR PROTOPLANET POPULATION SYNTHESIS

    SciTech Connect

    Masset, F. S.; Casoli, J. E-mail: jules.casoli@cea.f

    2010-11-10

    We provide torque formulae for low-mass planets undergoing type I migration in gaseous disks. These torque formulae put special emphasis on the horseshoe drag, which is prone to saturation: the asymptotic value reached by the horseshoe drag depends on a balance between coorbital dynamics (which tends to cancel out or saturate the torque) and diffusive processes (which tend to restore the unperturbed disk profiles, thereby desaturating the torque). We entertain the question of this asymptotic value and derive torque formulae that give the total torque as a function of the disk's viscosity and thermal diffusivity. The horseshoe drag features two components: one that scales with the vortensity gradient and another that scales with the entropy gradient and constitutes the most promising candidate for halting inward type I migration. Our analysis, which is complemented by numerical simulations, recovers characteristics already noted by numericists, namely, that the viscous timescale across the horseshoe region must be shorter than the libration time in order to avoid saturation and that, provided this condition is satisfied, the entropy-related part of the horseshoe drag remains large if the thermal timescale is shorter than the libration time. Side results include a study of the Lindblad torque as a function of thermal diffusivity and a contribution to the corotation torque arising from vortensity viscously created at the contact discontinuities that appear at the horseshoe separatrices. For the convenience of the reader mostly interested in the torque formulae, Section 8 is self-contained.

  18. The potential role of NGC 205 in generating Andromeda's vast thin corotating plane of satellite galaxies

    NASA Astrophysics Data System (ADS)

    Angus, Garry W.; Coppin, Paul; Gentile, Gianfranco; Diaferio, Antonaldo

    2016-11-01

    The Andromeda galaxy is observed to have a system of two large dwarf ellipticals and ˜13 smaller satellite galaxies that are currently corotating in a thin plane, in addition to 2 counter-rotating satellite galaxies. We explored the consistency of those observations with a scenario where the majority of the corotating satellite galaxies originated from a subhalo group, where NGC 205 was the host and the satellite galaxies occupied dark matter sub-subhaloes. We ran N-body simulations of a close encounter between NGC 205 and M31. In the simulations, NGC 205 was surrounded by massless particles to statistically sample the distribution of the sub-subhaloes expected in a subhalo that has a mass similar to NGC 205. We made Monte Carlo samplings and found that, using a set of reference parameters, the probability of producing a thinner distribution of sub-subhaloes than the observed NGC 205 + 15 smaller satellites (thus including the two counter-rotators, but excluding M32) increased from <10-8 for the initial distribution to ˜10-2 at pericentre. The probability of the simulated sub-subhaloes occupying the locations of the observed corotating satellites in the line-of-sight velocity versus projected on-sky distance plane is at most 2 × 10-3 for 11 out of 13 satellites. Increasing the mass of M31 and the extent of the initial distribution of sub-subhaloes gives a maximum probability of 4 × 10-3 for all 13 corotating satellites, but the probability of producing the thinness would drop to ˜10-3.

  19. Uncovering the planets and stellar activity of CoRoT-7 using only radial velocities

    NASA Astrophysics Data System (ADS)

    Faria, J. P.; Haywood, R. D.; Brewer, B. J.; Figueira, P.; Oshagh, M.; Santerne, A.; Santos, N. C.

    2016-04-01

    Stellar activity can induce signals in the radial velocities of stars, complicating the detection of orbiting low-mass planets. We present a method to determine the number of planetary signals present in radial-velocity datasets of active stars, using only radial-velocity observations. Instead of considering separate fits with different number of planets, we use a birth-death Markov chain Monte Carlo algorithm to infer the posterior distribution for the number of planets in a single run. In a natural way, the marginal distributions for the orbital parameters of all planets are also inferred. This method is applied to HARPS data of CoRoT-7. We confidently recover the orbits of both CoRoT-7b and CoRoT-7c although the data show evidence for the presence of additional signals. All data and software presented in this article are available online at http://https://github.com/j-faria/exoBD-CoRoT7

  20. Ironless armature torque motor

    NASA Technical Reports Server (NTRS)

    Fisher, R. L.

    1972-01-01

    Four iron-less armature torque motors, four Hall device position sensor assemblies, and two test fixtures were fabricated. The design approach utilized samarium cobalt permanent magnets, a large airgap, and a three-phase winding in a stationary ironless armature. Hall devices were employed to sense rotor position. An ironless armature torque motor having an outer diameter of 4.25 inches was developed to produce a torque constant of 65 ounce-inches per ampere with a resistance of 20.5 ohms. The total weight, including structural elements, was 1.58 pounds. Test results indicated that all specifications were met except for generated voltage waveform. It is recommended that investigations be made concerning the generated voltage waveform to determine if it may be improved.

  1. Merging of co-rotating vortices

    NASA Astrophysics Data System (ADS)

    Cerretelli, C.; Williamson, C. H. K.

    2001-11-01

    We present results from an experimental study on the interaction of two co-rotating trailing vortices. The flow is generated by towing a biplane wing system through a tank of water. The vortex dynamics, as a function of the Reynolds number (Re), are analyzed by means of DPIV. We find that vortex merging is essentially a 3-stage process. Initially, the vortices undergo a diffusive growth until the cores reach a critical size. This diffusion process can be either viscous (when Re < 530) or turbulent (when Re > 530). The second (convective) stage in vortex merging, involves a breaking of the initial symmetry of the vorticity field. At this point, the convective stage occurs, with a strong deformation of the vortex cores which start moving towards each other. The decomposition of the vorticity and velocity fields into symmetric and antisymmetric components shows that the antisymmetric vorticity pushes the vortices together, and causes the phenomenon of merging. The merging velocity can be measured from the antisymmetric velocity field, and agrees very well with direct measurement of the rate at which the centroids approach each other. The third stage of vortex merger is again a diffusive stage, whereby the final merging of the two vortices into one axisymmetric structure is achieved only by diffusion.

  2. Detection of Neptune-size planetary candidates with CoRoT data. Comparison with the planet occurrence rate derived from Kepler

    NASA Astrophysics Data System (ADS)

    Bonomo, A. S.; Chabaud, P. Y.; Deleuil, M.; Moutou, C.; Bouchy, F.; Cabrera, J.; Lanza, A. F.; Mazeh, T.; Aigrain, S.; Alonso, R.; Guterman, P.; Santerne, A.; Schneider, J.

    2012-11-01

    Context. The CoRoT space mission has been searching for transiting planets since the end of December 2006. It has led to the detection of about twenty Jupiter-size planets and three planets with radius Rp ≲ 5 R⊕. The latter are CoRoT-7b, the first super-Earth observed in transit, and two validated Neptunes, CoRoT-24b and c, in a multiple system. Aims: We aim to investigate the capability of CoRoT to detect small-size transiting planets in short-period orbits, and to compare the number of CoRoT planets with 2.0 ≤ Rp ≤ 4.0 R⊕ with the occurrence rate of small-size planets provided by the distribution of Kepler planetary candidates. Methods: We performed a test that simulates transits of super-Earths and Neptunes in real CoRoT light curves of six long observational runs and searches for them blindly by using the transit detection pipeline developed at the Laboratoire d'Astrophysique de Marseille. Results: The CoRoT detection rate of planets with radius between 2 and 4 R⊕ and orbital period P ≤ 20 days is 59% (31%) around stars brighter than r' = 14.0 (15.5). The vast majority of the missed planets went undetected because of a low transit signal-to-noise ratio (S/N). However, in some cases, additional instrumental or astrophysical noise may prevent even transits with relatively high S/N, i.e. S/N ≥ 10, from being revealed. By properly taking the CoRoT detection rate for Neptune-size planets (2 ≤ Rp ≤ 4 R⊕) and the transit probability into account, we found that according to the Kepler planet occurrence rate, CoRoT should have discovered 12 ± 2 Neptunes orbiting G and K dwarfs with P ≤ 17 days in six observational runs. This estimate must be compared with the validated Neptune CoRoT-24b and five CoRoT planetary candidates in the considered range of planetary radii, the nature of which is still unsolved. We thus found a disagreement with expectations from Kepler at 3σ or 5σ, assuming a blend fraction of 0% (six Neptunes) and 100% (one Neptune

  3. Corotational instability, magnetic resonances and global inertial-acoustic oscillations in magnetized black hole accretion discs

    NASA Astrophysics Data System (ADS)

    Fu, Wen; Lai, Dong

    2011-01-01

    Low-order, non-axisymmetric p-modes (also referred as inertial-acoustic modes) in hydrodynamic accretion discs around black holes are plausible candidates for high-frequency quasi-periodic oscillations (QPOs) observed in a number of accreting black hole systems. These modes are trapped in the innermost region of the accretion disc, and are subject to global instabilities due to wave absorption at the corotation resonance (where the wave pattern frequency ω/m equals the disc rotation rate Ω), when the fluid vortensity, ζ=κ2/(2ΩΣ) (where κ and Σ are the radial epicyclic frequency and disc surface density, respectively), has a positive gradient. We investigate the effects of disc magnetic fields on the wave absorption at corotation and the related wave super-reflection of the corotation barrier, and on the overstability of disc p-modes. In general, in the presence of magnetic fields, the p-modes have the character of inertial-fast magnetosonic waves in their propagation zone. For discs with a pure toroidal field, the corotation resonance is split into two magnetic resonances, where the wave frequency in the corotating frame of the fluid, ?, matches the slow magnetosonic wave frequency. Significant wave energy/angular momentum absorption occurs at both magnetic resonances, but with opposite signs, such that one of them enhances the super-reflection while the other diminishes it. The combined effect of the two magnetic resonances is to reduce the super-reflection and the growth rate of the overstable p-modes. Our calculations show that even a subthermal toroidal field (with the magnetic pressure less than the gas pressure) may suppress the overstability of hydrodynamic (B= 0) p-modes. For accretion discs with mixed (toroidal and vertical) magnetic fields, two additional Alfvén resonances appear, where ? matches the local Alfvén wave frequency. The effect of these additional resonances is to further reduce or diminish the growth rate of p-modes. Our results

  4. Methodology for Determining Limit Torques for Threaded Fasteners

    NASA Technical Reports Server (NTRS)

    Hissam, Andy

    2011-01-01

    In aerospace design, where minimizing weight is always a priority, achieving the full capacity from fasteners is essential. To do so, the initial bolt preload must be maximized. The benefits of high preload are well documented and include improved fatigue resistance, a stiffer joint, and resistance to loosening. But many factors like elastic interactions and embedment tend to lower the initial preload placed on the bolt. These factors provide additional motivation to maximize the initial preload. But, to maximize bolt preload, you must determine what torque to apply. Determining this torque is greatly complicated by the large preload scatter generally seen with torque control. This paper presents a detailed methodology for generating limit torques for threaded fasteners. This methodology accounts for the large scatter in preload found with torque control, and therefore, addresses the statistical nature of the problem. It also addresses prevailing torque, a feature common in aerospace fasteners. Although prevailing torque provides a desired locking feature, it can also increase preload scatter. In addition, it can limit the amount of preload that can be generated due to the torsion it creates in the bolt. This paper discusses the complications of prevailing torque and how best to handle it. A wide range of torque-tension bolt testing was conducted in support of this research. The results from this research will benefit the design engineer as well as analyst involved in the design of bolted joints, leading to better, more optimized structural designs.

  5. Torque-Splitting Gear Drive

    NASA Technical Reports Server (NTRS)

    Kish, J.

    1991-01-01

    Geared drive train transmits torque from input shaft in equal parts along two paths in parallel, then combines torques in single output shaft. Scheme reduces load on teeth of meshing gears while furnishing redundancy to protect against failures. Such splitting and recombination of torques common in design of turbine engines.

  6. Multiple-Cantilever Torque Sensor

    NASA Technical Reports Server (NTRS)

    Lurie, Boris J.; Schier, J. Alan; Socha, Michael

    1989-01-01

    Sensitivity to spurious loads small. High stiffness, high resolution, and ease of fabrication among features of specially designed torque sensor. Device flexible and sensitive to torque about its cylindrical axis and stiff enough to be insensitive to bending about any perpendicular axis. Measures and transmits torque between driving and driven plates.

  7. Experimental and theoretical investigation of solids conveying, melting and global behavior in self-wiping co-rotating twin screw extruders

    NASA Astrophysics Data System (ADS)

    Bawiskar, Santosh Shyam

    Modern self wiping co-rotating twin screw extruders are modular and starve fed. This leads to flow and conveying mechanisms that are different from the conventional flood fed single screw extruders. Since the mid 1980's, there have been many studies to model melt flow in different modules of the self wiping co-rotating twin screw extruder with varying degrees of complexity. On the other hand, the solids conveying and melting mechanisms in these machines have not received much attention. In this dissertation we describe a composite model for solids conveying, melting and melt flow in a modular co-rotating twin screw extruder. The solids conveying and melting mechanisms were first investigated by conducting flow visualization experiments. The solids conveying experiments were carried out by building transparent polymethyl methacrylate (PMMA) barrels and observing the pellet motions in the different elements of the self wiping co-rotating twin screw extruder. To understand the melting mechanisms several 'screw pull-out' experiments were conducted with various polymers under different operating conditions and using different screw configuration designs. The distribution of the polymer on the pulled screws was photographed. Subsequently polymer carcasses were stripped and cross-sectioned from the screws to study the progression of melting of solid pellets along the screw axis. Based on the experimental observations, new models for solids conveying and melting in modular self wiping co-rotating twin screw extruders were derived. These were then combined with the existing melt conveying models from our laboratories and the global performance of the self wiping co-rotating twin screw extruder was simulated. Computations were made for axial fill factor, pressure, temperature, melting profiles and also the power consumption, torque, specific energy consumption and average residence times. The simulation results were compared to experiments and were found to be in good

  8. Torque equilibrium attitudes for the Space Station

    NASA Technical Reports Server (NTRS)

    Thompson, Roger C.

    1993-01-01

    -up in the controllers would be due to electro-mechanical losses within the device. However, the atmospheric torques are proportional to the density of the atmosphere and the density varies with the orbital position, time of day, time of year, and the solar cycle. In addition, there are unmodeled disturbances and uncertainties in the mass and inertias. Therefore, there is no constant attitude that will completely balance the environmental torques and the dynamic TEA cannot be solved in closed form. The objective of this research was to determine a method to calculate a dynamic TEA such that the rate of momentum build-up in the controllers would be minimized and to implement this method in the MATRIX(x) simulation software by Integrated Systems, Inc.

  9. Co-Rotating Vortex Merger in 2- and 3-D

    NASA Astrophysics Data System (ADS)

    Jacob, Jd

    2000-11-01

    The interaction and merger of a co-rotating vortex pair is investigated experimentally in 2- and 3-D. A soap film membrane serves as the 2-D medium while a water tank serves as the 3-D facility. In both cases, pitching plates rotating in opposite directions are used to create co-rotating starting vortices. In both experiments, the motion of the vortices is observed while PIV is used to extract the velocity fields. In particular, the merger dynamics of the pair of co-rotating vortices with Re_Γ on the order of 10^2 - 10^5 is investigated. The differences between the 2- and 3-D cases are analyzed with emphasis on the details of the merger physics. Comparisons are made with computational analyses and the application of 2-D simulations to study 3-D vortex behavior is discussed.

  10. Corotation lag of the Jovian atmosphere, ionosphere, and magnetosphere

    NASA Astrophysics Data System (ADS)

    Huang, T. S.; Hill, T. W.

    1989-04-01

    The Jovian ionosphere-magnetosphere coupling model of Hill (1979) was modified to include the rotational slippage of the neutral atmosphere at ionospheric heights, relative to a frame of reference corotating rigidly with Jupiter. Equations were derived for the altitude distributions of ionospheric neutral and ion velocities, and a generalized expression was obtained for the corotation lag of the magnetosphere. The results of calculations provide independent support for the expectation that vertical mixing in Jupiter's atmosphere is much more vigorous at high latitudes than near the equator. They also indicate that the observed corotation lag in the magnetosphere and the Io torus is largely attributable to the slippage of the neutral atmosphere itself, rather than to the slippage of ionospheric ions relative to ionospheric neutrons, as previously suggested.

  11. Feasibility study for convertible engine torque converter

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The feasibility study has shown that a dump/fill type torque converter has excellent potential for the convertible fan/shaft engine. The torque converter space requirement permits internal housing within the normal flow path of a turbofan engine at acceptable engine weight. The unit permits operating the engine in the turboshaft mode by decoupling the fan. To convert to turbofan mode, the torque converter overdrive capability bring the fan speed up to the power turbine speed to permit engagement of a mechanical lockup device when the shaft speed are synchronized. The conversion to turbofan mode can be made without drop of power turbine speed in less than 10 sec. Total thrust delivered to the aircraft by the proprotor, fan, and engine during tansient can be controlled to prevent loss of air speed or altitude. Heat rejection to the oil is low, and additional oil cooling capacity is not required. The turbofan engine aerodynamic design is basically uncompromised by convertibility and allows proper fan design for quiet and efficient cruise operation. Although the results of the feasibility study are exceedingly encouraging, it must be noted that they are based on extrapolation of limited existing data on torque converters. A component test program with three trial torque converter designs and concurrent computer modeling for fluid flow, stress, and dynamics, updated with test results from each unit, is recommended.

  12. Negative Optical Torque

    PubMed Central

    Chen, Jun; Ng, Jack; Ding, Kun; Fung, Kin Hung; Lin, Zhifang; Chan, C. T.

    2014-01-01

    Light carries angular momentum, and as such it can exert torques on material objects. Applications of these opto-mechanical effects were limited initially due to their smallness in magnitude, but later becomes powerful and versatile after the invention of laser. Novel and practical approaches for harvesting light for particle rotation have since been demonstrated, where the structure is always subjected to a positive optical torque along a certain axis if the incident angular momentum has a positive projection on the same axis. We report here an interesting phenomenon of “negative optical torque”, meaning that incoming photons carrying angular momentum rotate an object in the opposite sense. Surprisingly this can be realized quite straightforwardly in simple planar structures. Field retardation is a necessary condition and discrete rotational symmetry of material object plays an important role. The optimal conditions are explored and explained. PMID:25226863

  13. Ground-based photometric support for the CoRoT mission by the CoRoT-Hungarian Asteroseismology Group

    NASA Astrophysics Data System (ADS)

    Bognár, Zs.; Paparó, M.

    2012-12-01

    The CoRoT-Hungarian Asteroseismology Group was established in 2005 and joined the preparatory work of the CoRoT Mission via an ESA PECS project. After the successful launch of the telescope, we have continued our work of ground-based multi-colour photometric observations and contributed to the analyses of CoRoT data. Our observations were focused on δ Scuti, γ Doradus, and RR Lyrae stars. The follow-up of some selected targets' pulsations in different wavelengths has provided valuable information for mode identification. We provided additional support by the confirmation of relatively faint variables' spectral types. We proved that our ground-based observations can help in the interpretation of a target with a contaminated CoRoT light curve. In this paper, we summarize our most important results of the photometric support for the CoRoT Mission. The CoRoT space mission was developed and is operated by the French space agency CNES, with participation of ESA's RSSD and Science Programmes, Austria, Belgium, Brazil, Germany, and Spain.

  14. First asteroseismic results from CoRoT

    NASA Astrophysics Data System (ADS)

    Michel, E.; Baglin, A.; Weiss, W. W.; Auvergne, M.; Catala, C.; Aerts, C.; Appourchaux, T.; Barban, C.; Baudin, F.; Briquet, M.; Carrier, F.; Degroote, P.; De Ridder, J.; Garcia, R. A.; Garrido, R.; Gutiérrez-Soto, J.; Kallinger, T.; Lefevre, L.; Neiner, C.; Poretti, E.; Samadi, R.; Sarro, L.; Alecian, G.; Andrade, L.; Ballot, J.; Benomar, O.; Berthomieu, G.; Boumier, P.; Charpinet, S.; de Batz, B.; Deheuvels, S.; Dupret, M.-A.; Emilio, M.; Fabregat, J.; Facanha, W.; Floquet, M.; Frémat, Y.; Fridlund, M.; Goupil, M.-J.; Grotsch-Noels, A.; Handler, G.; Huat, A.-L.; Hubert, A.-M.; Janot-Pacheco, E.; Kjeldsen, H.; Lebreton, Y.; Leroy, B.; Martayan, C.; Mathias, P.; Miglio, A.; Montalban, J.; Monteiro, M. J. P. F. G.; Mosser, B.; Provost, J; Regulo, C.; Renan de Medeiros, J.; Ribas, I.; Roca Cortés, T.; Roxburgh, I.; Suso, J.; Thoul, A.; Toutain, T.; Tiphene, D.; Turck-Chieze, S.; Vauclair, S.; Vauclair, G.; Zwintz, K.

    2008-12-01

    About one year after the end of the first observational run and six months after the first CoRoT data delivery, we comment the data exploitation progress for different types of stars. We consider first results to illustrate how these data of unprecedented quality shed a new light on the field of stellar seismology.

  15. Decrease of the Atmospheric Co-Rotation with Height

    ERIC Educational Resources Information Center

    Membrado, M.; Pacheco, A. F.

    2010-01-01

    Considering our atmosphere as a steady viscous gaseous envelope that co-rotates with the Earth, we obtain a solution for the form in which this induced rotational effect decreases as a function of the distances to the centre of the Earth and to the rotation axis. (Contains 1 figure.)

  16. Coupling Between Corotation And Lindblad Mean Motion Resonances

    NASA Astrophysics Data System (ADS)

    El Moutamid, Maryame; Sicardy, B.; Renner, S.

    2012-10-01

    We consider the classical Elliptic Restricted Three-Body Problem with two bodies (particle and satellite) orbiting a central planet. If we take into account the oblateness of the central body through the classical additional terms up to J_6, the secular terms causing the orbit precessions appear in the disturbing potential leading to the presence of two critical resonant arguments : Φ = (m+1)λ‧ + mλ + ω and Φ‧ = (m+1)λ‧ + mλ + ω‧ where m is an integer, λ and ω the mean longitude and the longitude of the periapsis of the particle, and the primed quantities apply to the satellite. The arguments Φ‧ and Φ respectively describe the Corotation Eccentric Resonance (CER) and the Lindblad Eccentric Resonance (LER). We developed a new model (the CoraLin model) which encapsulate in a simple adimensional form the coupling between the two resonances. We examine the asymptotic configurations where these resonances are well separated or completely superimposed. Poincaré surfaces of section reveal that in intermediate cases, the strong coupling between the resonances may lead to chaotic behavior. We apply this model to several recently discovered small Saturnian satellites dynamically linked to Mimas through first mean motion resonances : Anthe, Methone, and Aegaeon, all associated with arc material. All satellites are trapped in CER with Mimas and perturbed by the associated LER. We estimate the probability of capturing a satellite into a of CER with Mimas, as the orbit of the latter evolves through tidal effects, and discuss possible scenarios for the the dynamical origin of those moons.

  17. Prevailing Torque Locking Feature in Threaded Fasteners Using Anaerobic Adhesive

    NASA Technical Reports Server (NTRS)

    Hernandez, Alan; Hess, Daniel P.

    2016-01-01

    This paper presents results from tests to assess the use of anaerobic adhesive for providing a prevailing torque locking feature in threaded fasteners. Test procedures are developed and tests are performed on three fastener materials, four anaerobic adhesives, and both unseated assembly conditions. Five to ten samples are tested for each combination. Tests for initial use, reuse without additional adhesive, and reuse with additional adhesive are performed for all samples. A 48-hour cure time was used for all initial use and reuse tests. Test data are presented as removal torque versus removal angle with the specification required prevailing torque range added for performance assessment. Percent specification pass rates for the all combinations of fastener material, adhesive, and assembly condition are tabulated and reveal use of anaerobic adhesive as a prevailing torque locking feature is viable. Although not every possible fastener material and anaerobic adhesive combination provides prevailing torque values within specification, any combination can be assessed using the test procedures presented. Reuse without additional anaerobic adhesive generally provides some prevailing torque, and in some cases within specification. Reuse with additional adhesive often provides comparable removal torque data as in initial use.

  18. Torque detection using Brownian fluctuations.

    PubMed

    Volpe, Giovanni; Petrov, Dmitri

    2006-11-24

    We report the statistical analysis of the movement of a submicron particle confined in a harmonic potential in the presence of a torque. The absolute value of the torque can be found from the auto- and cross-correlation functions of the particle's coordinates. We experimentally prove this analysis by detecting the torque produced onto an optically trapped particle by an optical beam with orbital angular momentum.

  19. A 6-node co-rotational triangular elasto-plastic shell element

    NASA Astrophysics Data System (ADS)

    Li, Zhongxue; Xiang, Yu; Izzuddin, Bassam A.; Vu-Quoc, Loc; Zhuo, Xin; Zhang, Chuanjie

    2015-05-01

    A 6-node co-rotational triangular elasto-plastic shell element is developed. The local coordinate system of the element is defined by the vectors directing from one vertex to the other two vertices and their cross product. Based on such a co-rotational framework, the element rigid-body rotations are excluded in calculating the local nodal variables from the global nodal variables. The two smallest components of each nodal orientation vector are defined as rotational variables, resulting in the desired additive property for all nodal variables in a nonlinear incremental solution procedure. Different from other existing co-rotational finite element formulations, both the element tangent stiffness matrices in the local and in the global coordinate systems are symmetric owing to the commutativity of the nodal variables in calculating the second derivatives of the strain energy with respect to the local nodal variables and, through chain differentiation, with respect to the global nodal variables. For elasto-plastic analysis, the Maxwell-Huber-Hencky-von Mises yield criterion is employed together with the backward-Euler return-mapping method for the evaluation of the elasto-plastic stress state, where a consistent tangent modulus matrix is employed. To overcome locking problems, the assumed linear membrane strains and shear strains are obtained by using the line integration method proposed by MacNeal, and the assumed higher-order membrane strains are obtained by enforcing the stationarity of the mixed displacement-strain canonical functional, these assumed strains are then employed to replace the corresponding conforming strains. The reliability and convergence of the present 6-node triangular shell element formulation are verified through two elastic plate patch tests as well as two elastic and five elasto-plastic plate/shell problems undergoing large displacements and large rotations.

  20. Torque feedback transmission

    SciTech Connect

    Whalen, B.L.

    1987-01-20

    This patent describes an infinitely variable transmission of inline configuration for interconnecting a primer mover with a load for clutch free operation in a range of speed including hydraulic neutral comprising: a. planetary gear train means having a ring gear, planetary gears supported by a planetary gear carrier, and a sun gear, the sun gear being connected mechanically to the load, output shaft means for joining the sun gear to the load; b. variable torque feedback means comprising (i) a variable displacement hydraulic motor whose rotor shaft is in line with the output shaft means and drivingly connected to the prime mover and the planetary gear carrier during the full range of operation of the transmission, and (ii) a fixed displacement hydraulic pump connected hydraulically to the motor, the rotor shaft of the pump being connected mechanically to the ring gear and being axially displaced from the output shaft means; c. means for adjusting the displacement volume within the hydraulic motor for controlling the torque feedback in the transmission to provide infinitely variable coupling between the prime mover and the load over the full range of the transmission including hydraulic neutral; d. a speed reducer between the primer mover and the motor rotor shaft and a speed multiplier between the sun gear and the load; and e. mechanical transmission assembly means between the speed multiplier and the load in line with the motor rotor shaft and the output shaft means for providing selection of drive, reverse, park, and neutral.

  1. Radiative Torque Alignment: Essential Physical Processes

    NASA Astrophysics Data System (ADS)

    Hoang, Thiem; Lazarian, A.

    2007-05-01

    Aligned grains provide a unique way to trace magnetic field topology in many astrophysical environments. In Lazarian & Hoang (2006), we derived analytical expressions for radiative torque (RAT) components, and studied the dynamics of grains assuming that the maximal inertia axis is always parallel to angular momentum. In this paper, to get insight into the dynamics of grains when thermal fluctuations are accounted for, we use AMO, and perform analytically averaging for RAT components. In addition, we study the RAT alignment for irregular grains (shape 1 and 3). We also evaluate the influence of suprathermal torques arising from H2 formation, as well as randomizing collisions with atomic gas on the alignment of grains driven by radiative torques (RATs). Our study is both based on the analytical model (AMO) and numerical calculations of RATs for irregular grains. To describe the H2 formation torques and random collisions we use the Langevin equation approach. We show that when thermal fluctuations are included, for both AMO and irregular grains, RATs tend to align grains at attractor points with low angular momentum (low-J attractor point). We found that random collisions by atomic gas act to substantially disalign the grain alignment in the case the phase trajectory map has only the low-J attractor point. In particular, if there exist attractor points at high angular momentum in the phase trajectory map, gas bombardment can move grains from the low- J attractor point to the high-J attractor point. Thus the degree of alignment increases.

  2. Modelling grain alignment by radiative torques and hydrogen formation torques in reflection nebula

    NASA Astrophysics Data System (ADS)

    Hoang, Thiem; Lazarian, A.; Andersson, B.-G.

    2015-04-01

    Reflection nebulae - dense cores - illuminated by surrounding stars offer a unique opportunity to directly test our quantitative model of grain alignment based on radiative torques (RATs) and to explore new effects arising from additional torques. In this paper, we first perform detailed modelling of grain alignment by RATs for the IC 63 reflection nebula illuminated both by a nearby γ Cas star and the diffuse interstellar radiation field. We calculate linear polarization pλ of background stars by radiatively aligned grains and explore the variation of fractional polarization (pλ/AV) with visual extinction AV across the cloud. Our results show that the variation of pV/AV versus AV from the dayside of IC 63 to its centre can be represented by a power law (p_V/A_V∝ A_V^{η }) with different slopes depending on AV. We find a shallow slope η ˜ -0.1 for AV < 3 and a very steep slope η ˜ -2 for AV > 4. We then consider the effects of additional torques due to H2 formation and model grain alignment by joint action of RATs and H2 torques. We find that pV/AV tends to increase with an increasing magnitude of H2 torques. In particular, the theoretical predictions obtained for pV/AV and peak wavelength λmax in this case show an improved agreement with the observational data. Our results reinforce the predictive power of the RAT alignment mechanism in a broad range of environmental conditions and show the effect of pinwheel torques in environments with efficient H2 formation. Physical parameters involved in H2 formation may be constrained using detailed modelling of grain alignment combined with observational data. In addition, we discuss implications of our modelling for interpreting latest observational data by Planck and other ground-based instruments.

  3. Comparison of different passive knee extension torque-angle assessments.

    PubMed

    Freitas, Sandro R; Vaz, João R; Bruno, Paula M; Valamatos, Maria J; Mil-Homens, Pedro

    2013-11-01

    Previous studies have used isokinetic dynamometry to assess joint torques and angles during passive extension of the knee, often without reporting upon methodological errors and reliability outcomes. In addition, the reliability of the techniques used to measure passive knee extension torque-angle and the extent to which reliability may be affected by the position of the subjects is also unclear. Therefore, we conducted an analysis of the intra- and inter-session reliability of two methods of assessing passive knee extension: (A) a 2D kinematic analysis coupled to a custom-made device that enabled the direct measurement of resistance to stretch and (B) an isokinetic dynamometer used in two testing positions (with the non-tested thigh either flexed at 45° or in the neutral position). The intra-class correlation coefficients (ICCs) of torque, the slope of the torque-angle curve, and the parameters of the mathematical model that were fit to the torque-angle data for the above conditions were measured in sixteen healthy male subjects (age: 21.4 ± 2.1 yr; BMI: 22.6 ± 3.3 kg m(-2); tibial length: 37.4 ± 3.4 cm). The results found were: (1) methods A and B led to distinctly different torque-angle responses; (2) passive torque-angle relationship and stretch tolerance were influenced by the position of the non-tested thigh; and (3) ICCs obtained for torque were higher than for the slope and for the mathematical parameters that were fit to the torque-angle curve. In conclusion, the measurement method that is used and the positioning of subjects can influence the passive knee extension torque-angle outcome.

  4. Momentum Confinement at Low Torque

    SciTech Connect

    Solomon, W M; Burrell, K H; deGrassie, J S; Budny, R; Groebner, R J; Heidbrink, W W; Kinsey, J E; Kramer, G J; Makowski, M A; Mikkelsen, D; Nazikian, R; Petty, C C; Politzer, P A; Scott, S D; Van Zeeland, M A; Zarnstorff, M C

    2007-06-26

    Momentum confinement was investigated on DIII-D as a function of applied neutral beam torque at constant normalized {beta}{sub N}, by varying the mix of co (parallel to the plasma current) and counter neutral beams. Under balanced neutral beam injection (i.e. zero total torque to the plasma), the plasma maintains a significant rotation in the co-direction. This 'intrinsic' rotation can be modeled as being due to an offset in the applied torque (i.e. an 'anomalous torque'). This anomalous torque appears to have a magnitude comparable to one co-neutral beam source. The presence of such an anomalous torque source must be taken into account to obtain meaningful quantities describing momentum transport, such as the global momentum confinement time and local diffusivities. Studies of the mechanical angular momentum in ELMing H-mode plasmas with elevated q{sub min} show that the momentum confinement time improves as the torque is reduced. In hybrid plasmas, the opposite effect is observed, namely that momentum confinement improves at high torque/rotation. The relative importance of E x B shearing between the two is modeled using GLF23 and may suggest a possible explanation.

  5. 14 CFR 27.361 - Engine torque.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 27.361 Engine torque. (a) For... compressor jamming). (b) For reciprocating engines, the limit torque may not be less than the mean torque for... System Loads...

  6. 14 CFR 27.361 - Engine torque.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 27.361 Engine torque. (a) For... compressor jamming). (b) For reciprocating engines, the limit torque may not be less than the mean torque for... System Loads...

  7. 14 CFR 27.361 - Engine torque.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 27.361 Engine torque. (a) For... compressor jamming). (b) For reciprocating engines, the limit torque may not be less than the mean torque for... System Loads...

  8. 14 CFR 27.361 - Engine torque.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 27.361 Engine torque. (a) For... compressor jamming). (b) For reciprocating engines, the limit torque may not be less than the mean torque for... System Loads...

  9. 14 CFR 27.361 - Engine torque.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 27.361 Engine torque. (a) For... compressor jamming). (b) For reciprocating engines, the limit torque may not be less than the mean torque for... System Loads...

  10. Investigating Stellar Activity with CoRoT Observations

    NASA Astrophysics Data System (ADS)

    Mathur, S.; Salabert, D.; García, R. A.; Régulo, C.; Ballot, J.; Metcalfe, T. S.

    2012-09-01

    The recent study of the CoRoT target HD 49933 found evidence of variability in its magnetic activity. This was the first time that stellar activity had been detected using asteroseismic data. For the Sun and HD 49933, we observe an increase of the p-mode frequencies and a decrease of the maximum amplitude per radial mode when the activity level is higher. Moreover a similar behavior of the frequency shifts with frequency has been found for the Sun and HD 49933. We study three other CoRoT targets, for which modes have been detected and well identified: HD 181420, HD 49385, and HD 52265 (which is hosting a planet). We report on how the seismic parameters (frequency shifts and amplitude) vary during the observation of these stars.

  11. THE MASS OF CoRoT-7b

    SciTech Connect

    Hatzes, Artie P.; Wuchterl, Guenther; Fridlund, Malcolm; Gandolfi, Davide; Nachmani, Gil; Mazeh, Tsevi; Valencia, Diana; Hebrard, Guillaume; Borde, Pascal; Carone, Ludmila; Paetzold, Martin; Udry, Stephane; Bouchy, Francois; Deleuil, Magali; Moutou, Claire; Barge, Pierre; Deeg, Hans; Tingley, Brandon; Dvorak, Rudolf; Ferraz-Mello, Sylvio E-mail: malcolm.fridlund@esa.int; and others

    2011-12-10

    The mass of CoRoT-7b, the first transiting super-Earth exoplanet, is still a subject of debate. A wide range of masses have been reported in the literature ranging from as high as 8 M{sub Circled-Plus} to as low as 2.3 M{sub Circled-Plus }. This range in mass is largely due to the activity level of the star that contributes a significant amount of radial velocity (RV) 'jitter' and how the various methods correct this jitter. Although most mass determinations give a density consistent with a rocky planet, the lower value permits a bulk composition that can be up to 50% water. We present an analysis of the CoRoT-7b RV measurements that uses very few and simple assumptions in treating the activity signal. By analyzing those RV data for which multiple measurements were made in a given night, we remove the activity related RV contribution without any a priori model. We argue that the contribution of activity to the final RV curve is negligible and that the K-amplitude due to the planet is well constrained. This yields a mass of 7.42 {+-} 1.21 M{sub Circled-Plus} and a mean density of {rho} = 10.4 {+-} 1.8 gm cm{sup -3}. CoRoT-7b is similar in mass and radius to the second rocky planet to be discovered, Kepler-10b, and within the errors they have identical bulk densities-they are virtual twins. These bulk densities lie close to the density-radius relationship for terrestrial planets similar to what is seen for Mercury. CoRoT-7b and Kepler-10b may have an internal structure more like Mercury than the Earth.

  12. Energetic particle acceleration at corotating interaction regions: Ulysses results

    SciTech Connect

    Desai, M.I.; Marsden, R.G.; Sanderson, T.R.; Gosling, J.T.

    1997-07-01

    We present here statistical properties of energetic ions (tilde 1 MeV) accelerated by corotating interaction regions observed at the Ulysses spacecraft. We have correlated the tilde 1 MeV proton intensity measured near the trailing edges of the interaction regions with their compression ratio. We interpret our results in terms of the plasma conditions experienced at Ulysses and identify a likely source of the low energy seed particles accelerated at the interaction regions.

  13. Corotating pressure waves without streams in the solar wind

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.

    1983-01-01

    Voyager 1 and 2 magnetic field and plasma data are presented which demonstrate the existence of large scale, corotating, non-linear pressure waves between 2 AU and 4 AU that are not accompanied by fast streams. The pressure waves are presumed to be generated by corotating streams near the Sun. For two of the three pressure waves that are discussed, the absence of a stream is probably a real, physical effect, viz., a consequence of deceleration of the stream by the associated compression wave. For the third pressure wave, the apparent absence of a stream may be a geometrical effect; it is likely that the stream was at latitudes just above those of the spacecraft, while the associated shocks and compression wave extended over a broader range of latitudes so that they could be observed by the spacecraft. It is suggested that the development of large-scale non-linear pressure waves at the expense of the kinetic energy of streams produces a qualitative change in the solar wind in the outer heliosphere. Within a few AU the quasi-stationary solar wind structure is determined by corotating streams whose structure is determined by the boundary conditions near the Sun.

  14. Migration of accreting planets in radiative discs from dynamical torques

    NASA Astrophysics Data System (ADS)

    Pierens, A.; Raymond, S. N.

    2016-11-01

    We present the results of hydrodynamical simulations of the orbital evolution of planets undergoing runaway gas accretion in radiative discs. We consider accreting disc models with constant mass flux through the disc, and where radiative cooling balances the effect of viscous heating and stellar irradiation. We assume that 20-30 M⊕ giant planet cores are formed in the region where viscous heating dominates and migrate outward under the action of a strong entropy-related corotation torque. In the case where gas accretion is neglected and for an α viscous stress parameter α = 2 × 10-3, we find evidence for strong dynamical torques in accreting discs with accretion rates {dot{M}}≳ 7× 10^{-8} M_{⊙} yr{}^{-1}. Their main effect is to increase outward migration rates by a factor of ˜2 typically. In the presence of gas accretion, however, runaway outward migration is observed with the planet passing through the zero-torque radius and the transition between the viscous heating and stellar heating dominated regimes. The ability for an accreting planet to enter a fast migration regime is found to depend strongly on the planet growth rate, but can occur for values of the mass flux through the disc of {dot{M}}≳ 5× 10^{-8} M_{⊙} yr{}^{-1}. We find that an episode of runaway outward migration can cause an accreting planet formed in the 5-10 au region to temporarily orbit at star-planet separations as large as ˜60-70 au. However, increase in the amplitude of the Lindblad torque associated with planet growth plus change in the streamline topology near the planet systematically cause the direction of migration to be reversed. Subsequent evolution corresponds to the planet migrating inward rapidly until it becomes massive enough to open a gap in the disc and migrate in the type II regime. Our results indicate that a planet can reach large orbital distances under the combined effect of dynamical torques and gas accretion, but an alternative mechanism is required to

  15. Birefringent torque sensor for motors

    NASA Astrophysics Data System (ADS)

    Chung, Dukki; Merat, Francis L.; Discenzo, Fred M.; Harris, James S.

    1998-12-01

    Birefringent optical materials can be used to convert mechanical strain into fringe patterns of optical intensity which have typically been used to measure surface stains or stresses. In this paper a system will be described that uses a photoelastic transducer, linear sensor array, and neural network image processing to estimate the load torque for stationary and rotating motor shafts up to 1500 rpm. A photoelastic polymer coupling is attached to the shaft, and illuminated by polarized light. As the shaft torque varies the photoelastic plastic coupling experiences torsional strain. This results in a corresponding 2D fringe pattern when viewed through an optical polarizer. The strain that causes this observed pattern in a complex function of the applied torque applied to the shaft. A neural network is trained with the fringe patterns corresponding to calibrated load torques as measured by a laboratory strain gauge torque sensor. Experimental results show that the neural network torque estimator can accurately estimate the applied torque for both static and rotating shafts.

  16. Planetary transit candidates in the CoRoT LRa01 field

    NASA Astrophysics Data System (ADS)

    Carone, L.; Gandolfi, D.; Cabrera, J.; Hatzes, A. P.; Deeg, H. J.; Csizmadia, Sz.; Pätzold, M.; Weingrill, J.; Aigrain, S.; Alonso, R.; Alapini, A.; Almenara, J.-M.; Auvergne, M.; Baglin, A.; Barge, P.; Bonomo, A. S.; Bordé, P.; Bouchy, F.; Bruntt, H.; Carpano, S.; Cochran, W. D.; Deleuil, M.; Díaz, R. F.; Dreizler, S.; Dvorak, R.; Eislöffel, J.; Eigmüller, P.; Endl, M.; Erikson, A.; Ferraz-Mello, S.; Fridlund, M.; Gazzano, J.-C.; Gibson, N.; Gillon, M.; Gondoin, P.; Grziwa, S.; Günther, E. W.; Guillot, T.; Hartmann, M.; Havel, M.; Hébrard, G.; Jorda, L.; Kabath, P.; Léger, A.; Llebaria, A.; Lammer, H.; Lovis, C.; MacQueen, P. J.; Mayor, M.; Mazeh, T.; Moutou, C.; Nortmann, L.; Ofir, A.; Ollivier, M.; Parviainen, H.; Pepe, F.; Pont, F.; Queloz, D.; Rabus, M.; Rauer, H.; Régulo, C.; Renner, S.; de La Reza, R.; Rouan, D.; Santerne, A.; Samuel, B.; Schneider, J.; Shporer, A.; Stecklum, B.; Tal-Or, L.; Tingley, B.; Udry, S.; Wuchterl, G.

    2012-02-01

    Context. CoRoT is a pioneering space mission whose primary goals are stellar seismology and extrasolar planets search. Its surveys of large stellar fields generate numerous planetary candidates whose lightcurves have transit-like features. An extensive analytical and observational follow-up effort is undertaken to classify these candidates. Aims: We present the list of planetary transit candidates from the CoRoT LRa01 star field in the Monoceros constellation toward the Galactic anti-center direction. The CoRoT observations of LRa01 lasted from 24 October 2007 to 3 March 2008. Methods: We acquired and analyzed 7470 chromatic and 3938 monochromatic lightcurves. Instrumental noise and stellar variability were treated with several filtering tools by different teams from the CoRoT community. Different transit search algorithms were applied to the lightcurves. Results: Fifty-one stars were classified as planetary transit candidates in LRa01. Thirty-seven (i.e., 73% of all candidates) are "good" planetary candidates based on photometric analysis only. Thirty-two (i.e., 87% of the "good" candidates) have been followed-up. At the time of writing twenty-two cases were solved and five planets were discovered: three transiting hot-Jupiters (CoRoT-5b, CoRoT-12b, and CoRoT-21b), the first terrestrial transiting planet (CoRoT-7b), and another planet in the same system (CoRoT-7c, detected by radial velocity survey only). Evidence of another non-transiting planet in the CoRoT-7 system, namely CoRoT-7d, was recently found as well. The CoRoT space mission, launched on December 27, 2006, has been developed and is operated by CNES, with contributions of Austria, Belgium, Brazil, ESA (RSSD and Science Program), Germany and Spain.

  17. Quick torque coupling

    DOEpatents

    Luft, Peter A.

    2009-05-12

    A coupling for mechanically connecting modular tubular struts of a positioning apparatus or space frame, comprising a pair of toothed rings (10, 12) attached to separate strut members (16), the teeth (18, 20) of the primary rings (10, 12) mechanically interlocking in both an axial and circumferential manner, and a third part comprising a sliding, toothed collar (14) the teeth (22) of which interlock the teeth (18, 20) of the primary rings (10, 12), preventing them from disengaging, and completely locking the assembly together. A secondary mechanism provides a nesting force for the collar, and/or retains it. The coupling is self-contained and requires no external tools for installation, and can be assembled with gloved hands in demanding environments. No gauging or measured torque is required for assembly. The assembly can easily be visually inspected to determine a "go" or "no-go" status. The coupling is compact and relatively light-weight. Because of it's triply interlocking teeth, the connection is rigid. The connection does not primarily rely on clamps, springs or friction based fasteners, and is therefore reliable in fail-safe applications.

  18. Deformable micro torque swimmer

    NASA Astrophysics Data System (ADS)

    Ishikawa, Takuji; Tanaka, Tomoyuki; Omori, Toshihiro; Imai, Yohsuke

    2015-11-01

    We investigated the deformation of a ciliate swimming freely in a fluid otherwise at rest. The cell body was modeled as a capsule with a hyper elastic membrane enclosing Newtonian fluid. Thrust forces due to the ciliary beat were modeled as torques distributed above the cell body. Effects of the membrane elasticity, the aspect ratio of cell's reference shape and the density difference between the cell and the surrounding fluid were investigated. The results showed that the cell deformed like heart shape when Capillary number (Ca) was sufficiently large, and the swimming velocity decreased as Ca was increased. The gravity effect on the membrane tension suggested that the upwards and downwards swimming velocities of Paramecium might be reglated by the calcium ion channels distributed locally around the anterior end. Moreover, the gravity induced deformation made a cell directed vertically downwards, which resulted in a positive geotaxis like behavior with physical origin. These results are important to understand physiology of ciliate's biological responses to mechanical stimuli.

  19. Zero torque gear head wrench

    NASA Technical Reports Server (NTRS)

    Mcdougal, A. R.; Norman, R. M. (Inventor)

    1976-01-01

    A gear head wrench particularly suited for use in applying torque to bolts without transferring torsional stress to bolt-receiving structures is introduced. The wrench is characterized by a coupling including a socket, for connecting a bolt head with a torque multiplying gear train, provided within a housing having an annulus concentrically related to the socket and adapted to be coupled with a spacer interposed between the bolt head and the juxtaposed surface of the bolt-receiving structure for applying a balancing counter-torque to the spacer as torque is applied to the bolt head whereby the bolt-receiving structure is substantially isolated from torsional stress. As a result of the foregoing, the operator of the wrench is substantially isolated from any forces which may be imposed.

  20. Intraband and interband spin-orbit torques in noncentrosymmetric ferromagnets

    NASA Astrophysics Data System (ADS)

    Li, Hang; Gao, H.; Zârbo, Liviu P.; Výborný, K.; Wang, Xuhui; Garate, Ion; Doǧan, Fatih; Čejchan, A.; Sinova, Jairo; Jungwirth, T.; Manchon, Aurélien

    2015-04-01

    Intraband and interband contributions to the current-driven spin-orbit torque in magnetic materials lacking inversion symmetry are theoretically studied using the Kubo formula. In addition to the current-driven fieldlike torque TFL=τFLm ×uso (uso being a unit vector determined by the symmetry of the spin-orbit coupling), we explore the intrinsic contribution arising from impurity-independent interband transitions and producing an anti-damping-like torque of the form TDL=τDLm ×(uso×m ) . Analytical expressions are obtained in the model case of a magnetic Rashba two-dimensional electron gas, while numerical calculations have been performed on a dilute magnetic semiconductor (Ga,Mn)As modeled by the Kohn-Luttinger Hamiltonian exchange coupled to the Mn moments. Parametric dependencies of the different torque components and similarities to the analytical results of the Rashba two-dimensional electron gas in the weak disorder limit are described.

  1. Charge-Induced Spin Torque in Anomalous Hall Ferromagnets.

    PubMed

    Nomura, Kentaro; Kurebayashi, Daichi

    2015-09-18

    We demonstrate that spin-orbit coupled electrons in a magnetically doped system exert a spin torque on the local magnetization, without a flowing current, when the chemical potential is modulated in a magnetic field. The spin torque is proportional to the anomalous Hall conductivity, and its effective field strength may overcome the Zeeman field. Using this effect, the direction of the local magnetization is switched by gate control in a thin film. This charge-induced spin torque is essentially an equilibrium effect, in contrast to the conventional current-induced spin-orbit torque, and, thus, devices using this operating principle possibly have higher efficiency than the conventional ones. In addition to a comprehensive phenomenological derivation, we present a physical understanding based on a model of a Dirac-Weyl semimetal, possibly realized in a magnetically doped topological insulator. The effect might be realized also in nanoscale transition materials, complex oxide ferromagnets, and dilute magnetic semiconductors. PMID:26431012

  2. Knudsen torque: A rotational mechanism driven by thermal force

    NASA Astrophysics Data System (ADS)

    Li, Qi; Liang, Tengfei; Ye, Wenjing

    2014-09-01

    Thermally induced mechanical loading has been shown to have significant effects on micro- and nano-objects immersed in a gas with a nonuniform temperature field. While the majority of existing studies and related applications focus on forces, we investigate the torque, and thus the rotational motion, produced by such a mechanism. Our study has found that a torque can be induced if the configuration of the system is asymmetric. In addition, both the magnitude and the direction of the torque depend highly on the system configuration, indicating the possibility of manipulating the rotational motion via geometrical design. Based on this feature, two types of rotational micromotor that are of practical importance, namely pendulum motor and unidirectional motor, are designed. The magnitude of the torque at Kn =0.5 can reach to around 2nN×μm for a rectangular microbeam with a length of 100μm.

  3. Corotational Tomography of Heliospheric Features Using Global Thomson Scattering Data

    NASA Astrophysics Data System (ADS)

    Jackson, Bernard V.; Hick, P. Paul

    2002-12-01

    The Air Force/NASA Solar Mass Ejection Imager (SMEI) will provide two-dimensional images of the sky in visible light with high (0.1%) photometric precision, and unprecedented sky coverage and cadence. To optimize the information available from these images they must be interpreted in three dimensions. We have developed a Computer Assisted Tomography (CAT) technique that fits a three-dimensional kinematic heliospheric model to remotely-sensed Thomson scattering observations. This technique is designed specifically to determine the corotating background solar wind component from data provided by instruments like SMEI. Here, we present results from this technique applied to the Helios spacecraft photometer observations. The tomography program iterates to a least-squares solution of observed brightnesses using solar rotation, spacecraft motion and solar wind outflow to provide perspective views of each point in space covered by the observations. The corotational tomography described here is essentially the same as used by Jackson et al. (1998) for the analysis of interplanetary scintillation (IPS) observations. While IPS observations are related indirectly to the solar wind density through an assumed (and uncertain) relationship between small-scale density fluctuations and density, Thomson scattering physics is more straightforward, i.e., the observed brightness depends linearly on the solar wind density everywhere in the heliosphere. Consequently, Thomson scattering tomography can use a more direct density-convergence criterion to match observed Helios photometer brightness to brightness calculated from the model density. The general similarities between results based on IPS and Thomson scattering tomography validate both techniques and confirm that both observe the same type of solar wind structures. We show results for Carrington rotation 1653 near solar minimum. We find that longitudinally segmented dense structures corotate with the Sun and emanate from near the

  4. Spin-orbit torques and anisotropic magnetization damping in skyrmion crystals

    NASA Astrophysics Data System (ADS)

    Hals, Kjetil M. D.; Brataas, Arne

    2014-02-01

    The length scale of the magnetization gradients in chiral magnets is determined by the relativistic Dzyaloshinskii-Moriya interaction. Thus, even conventional spin-transfer torques are controlled by the relativistic spin-orbit coupling in these systems, and additional relativistic corrections to the current-induced torques and magnetization damping become important for a complete understanding of the current-driven magnetization dynamics. We theoretically study the effects of reactive and dissipative homogeneous spin-orbit torques and anisotropic damping on the current-driven skyrmion dynamics in cubic chiral magnets. Our results demonstrate that spin-orbit torques play a significant role in the current-induced skyrmion velocity. The dissipative spin-orbit torque generates a relativistic Magnus force on the skyrmions, whereas the reactive spin-orbit torque yields a correction to both the drift velocity along the current direction and the transverse velocity associated with the Magnus force. The spin-orbit torque corrections to the velocity scale linearly with the skyrmion size, which is inversely proportional to the spin-orbit coupling. Consequently, the reactive spin-orbit torque correction can be the same order of magnitude as the nonrelativistic contribution. More importantly, the dissipative spin-orbit torque can be the dominant force that causes a deflected motion of the skyrmions if the torque exhibits a linear or quadratic relationship with the spin-orbit coupling. In addition, we demonstrate that the skyrmion velocity is determined by anisotropic magnetization damping parameters governed by the skyrmion size.

  5. Helicopter anti-torque system using fuselage strakes

    NASA Technical Reports Server (NTRS)

    Kelley, Henry L. (Inventor); Wilson, John C. (Inventor)

    1987-01-01

    The improvement of the helicopter torque control system is discussed. At low to medium forward speeds helicopter performance is limited by the effectiveness of the means for counteracting main rotor torque and controlling sideslip airloads. These problems may be overcome by mounting strakes on the aft fuselage section. For single rotor helicopters whose main rotor rotates counter-clockwise as viewed from above, one of the strakes would be mounted in the upper lefthand quadrant and the second in the lower left hand quadrant. The strakes alter the air flow around the fuselage by separating the flow so as to produce lateral airloads on the tail boom which oppose main-rotor torque. The upper strake operates in a right crosswind to oppose main rotor torque, and the lower strake has effect in left crosswinds. The novelty of this invention resides in the simple and economical manner in which the helicopter tail boom may be modified by the addition of strakes in order to increase torque control, and reduce the need for supplemental mechanical means of torque control.

  6. Split torque transmission load sharing

    NASA Technical Reports Server (NTRS)

    Krantz, T. L.; Rashidi, M.; Kish, J. G.

    1992-01-01

    Split torque transmissions are attractive alternatives to conventional planetary designs for helicopter transmissions. The split torque designs can offer lighter weight and fewer parts but have not been used extensively for lack of experience, especially with obtaining proper load sharing. Two split torque designs that use different load sharing methods have been studied. Precise indexing and alignment of the geartrain to produce acceptable load sharing has been demonstrated. An elastomeric torque splitter that has large torsional compliance and damping produces even better load sharing while reducing dynamic transmission error and noise. However, the elastomeric torque splitter as now configured is not capable over the full range of operating conditions of a fielded system. A thrust balancing load sharing device was evaluated. Friction forces that oppose the motion of the balance mechanism are significant. A static analysis suggests increasing the helix angle of the input pinion of the thrust balancing design. Also, dynamic analysis of this design predicts good load sharing and significant torsional response to accumulative pitch errors of the gears.

  7. Power spectral signatures of interplanetary corotating and transient flows

    NASA Technical Reports Server (NTRS)

    Goldstein, M. L.; Burlaga, L. F.; Matthaeus, W. H.

    1984-01-01

    Studies of the time behavior of the galactic cosmic ray intensity have concluded that long term decreases in the intensity are generally associated with systems of interplanetary flows that contain flare generated shock waves, magnetic clouds and other transient phenomena. The magnetic field power spectral signatures of such flow systems are compared to power spectra obtained during times when the solar wind is dominated by stable corotating streams that do not usually produce long-lived reduction in the cosmic ray intensity. The spectral signatures of these two types of regimes (transient and corotating) are distinct. However, the distinguishing features are not the same throughout the heliosphere. In data collected beyond 1 AU the primary differences are in the power spectra of the magnitude of the magnetic field rather than in the power in the field components. Consequently, decreases in cosmic ray intensity are very likely due to magnetic mirror forces and gradient drifts rather than to small angle scattering due to cyclotron wave-particle interactions.

  8. DIRECT OBSERVATION OF A COROTATING INTERACTION REGION BY THREE SPACECRAFT

    SciTech Connect

    Tappin, S. J. Howard, T. A

    2009-09-10

    White-light observations of interplanetary disturbances have been dominated by interplanetary coronal mass ejections (ICMEs). This is because the other type of disturbance, the corotating interaction region (CIR), has proved difficult to detect using white-light imagers. Recently, a number of papers have appeared presenting CIR observations using the Solar Terrestrial Relations Observatory (STEREO) Heliospheric Imagers (HIs), but have mostly only focused on a single spacecraft and imager. In this paper, we present observations of a single CIR that was observed by all three current white-light heliospheric imagers (SMEI and both STEREO HIs), as well as the in situ instruments on both STEREO satellites and ACE. We begin with a discussion of the geometry of the CIR structure, and show how the apparent leading edge structure is expected to change as it corotates relative to the observer. We use these calculations to predict elongation-time profiles for CIRs of different speeds for each of the imagers, and also to predict the arrival times at the in situ instruments. We show that although all three measured different parts, they combine to produce a self-consistent picture of the CIR. Finally, we offer some thoughts on why CIRs have proved so difficult to detect in white-light heliospheric images.

  9. A new SMA shell element based on the corotational formulation

    NASA Astrophysics Data System (ADS)

    Bisegna, P.; Caselli, F.; Marfia, S.; Sacco, E.

    2014-11-01

    Aim of this paper is to develop a new shape memory alloy (SMA) facet-shell finite element accounting for material and geometric nonlinearities. A corotational formulation is exploited, able to filter out large rigid-body motions from the element transformation. Accordingly, a geometrically linear core-element is employed, along with a SMA constitutive model formulated in the small strain framework. In particular, in accordance with the formulation of the classical thin shell theory, a plane-stress SMA model accounting for the pseudo-elastic as well as the shape memory effect is adopted. The time integration of the evolutive equation is performed developing a step-by-step backward-Euler numerical procedure. A highly efficient implementation of the corotational machinery is used, endowed with a fully consistent tangent stiffness. Applications are carried out for assessing the performances of the developed computational procedure and to investigate on some interesting engineering examples. The numerical results show the effectiveness of the proposed shell element, whose simplicity makes it attractive for the design of new advanced SMA-based devices undergoing significant configuration changes during their operation.

  10. Ankle and hip postural strategies defined by joint torques.

    PubMed

    Runge, C F; Shupert, C L; Horak, F B; Zajac, F E

    1999-10-01

    Previous studies have identified two discrete strategies for the control of posture in the sagittal plane based on EMG activations, body kinematics, and ground reaction forces. The ankle strategy was characterized by body sway resembling a single-segment-inverted pendulum and was elicited on flat support surfaces. In contrast, the hip strategy was characterized by body sway resembling a double-segment inverted pendulum divided at the hip and was elicited on short or compliant support surfaces. However, biomechanical optimization models have suggested that hip strategy should be observed in response to fast translations on a flat surface also, provided the feet are constrained to remain in contact with the floor and the knee is constrained to remain straight. The purpose of this study was to examine the experimental evidence for hip strategy in postural responses to backward translations of a flat support surface and to determine whether analyses of joint torques would provide evidence for two separate postural strategies. Normal subjects standing on a flat support surface were translated backward with a range of velocities from fast (55 cm/s) to slow (5 cm/s). EMG activations and joint kinematics showed pattern changes consistent with previous experimental descriptions of mixed hip and ankle strategy with increasing platform velocity. Joint torque analyses revealed the addition of a hip flexor torque to the ankle plantarflexor torque during fast translations. This finding indicates the addition of hip strategy to ankle strategy to produce a continuum of postural responses. Hip torque without accompanying ankle torque (pure hip strategy) was not observed. Although postural control strategies have previously been defined by how the body moves, we conclude that joint torques, which indicate how body movements are produced, are useful in defining postural control strategies. These results also illustrate how the biomechanics of the body can transform discrete control

  11. Ankle and hip postural strategies defined by joint torques

    NASA Technical Reports Server (NTRS)

    Runge, C. F.; Shupert, C. L.; Horak, F. B.; Zajac, F. E.; Peterson, B. W. (Principal Investigator)

    1999-01-01

    Previous studies have identified two discrete strategies for the control of posture in the sagittal plane based on EMG activations, body kinematics, and ground reaction forces. The ankle strategy was characterized by body sway resembling a single-segment-inverted pendulum and was elicited on flat support surfaces. In contrast, the hip strategy was characterized by body sway resembling a double-segment inverted pendulum divided at the hip and was elicited on short or compliant support surfaces. However, biomechanical optimization models have suggested that hip strategy should be observed in response to fast translations on a flat surface also, provided the feet are constrained to remain in contact with the floor and the knee is constrained to remain straight. The purpose of this study was to examine the experimental evidence for hip strategy in postural responses to backward translations of a flat support surface and to determine whether analyses of joint torques would provide evidence for two separate postural strategies. Normal subjects standing on a flat support surface were translated backward with a range of velocities from fast (55 cm/s) to slow (5 cm/s). EMG activations and joint kinematics showed pattern changes consistent with previous experimental descriptions of mixed hip and ankle strategy with increasing platform velocity. Joint torque analyses revealed the addition of a hip flexor torque to the ankle plantarflexor torque during fast translations. This finding indicates the addition of hip strategy to ankle strategy to produce a continuum of postural responses. Hip torque without accompanying ankle torque (pure hip strategy) was not observed. Although postural control strategies have previously been defined by how the body moves, we conclude that joint torques, which indicate how body movements are produced, are useful in defining postural control strategies. These results also illustrate how the biomechanics of the body can transform discrete control

  12. VizieR Online Data Catalog: CoRoT observation log (N2-4.4) (CoRoT 2016)

    NASA Astrophysics Data System (ADS)

    COROT Team

    2014-03-01

    CoRoT, a space astronomy mission, has measured photometric micro-variability of stars from minutes to months (up to 150 days) with a high duty cycle (more than 90%). The mission was led by CNES in association with four French laboratories and 7 participating countries and agencies (Austria, Belgium, Brazil, Germany, Spain, and the ESA Science Programme). The satellite was composed of a PROTEUS platform (the 3rd in the series) and a unique instrument: a stellar rapid photometer. It was launched on December 27th 2006 by a Soyuz Rocket, from Bakonour. The mission has lasted almost 6 years (the nominal 3-year duration and a 3-year extension) and has observed more than 160 000 stars. It stopped sending data on November 2nd 2012. Two regions of the sky were accessible for long period of time: circles of 10 degrees centered on the equator around alpha=06:50 and alpha=18:50. They were called the CoRoT eyes: the "anticenter" and the "center eye" (as they are approximately in these directions). Each pointing covers 1.4x2.8 square degrees within one of those CoRoT eyes. The original scientific objectives were focussed on the study of stellar pulsations (asteroseismology) to probe the internal structure of stars, and the detection of small exoplanets through their "transit" in front of their host star, and the measurement of their size. This lead to introduce two modes of observations, working simultaneously: - The "bright star" mode dedicated to very precise seismology of a small sample of bright and closeby stars - The "faint star" mode, observing a very large number of stars at the same time, to detect transits, which are rare events, as they imply the alignment of the star, the planet and the observer. The large amount of data gathered in this mode turned out to be extremely fruitful for many topics of stellar physics. Beyond these two initial objectives, CoRoT data revealed stellar variability associated with various other phenomena: granulation, rotational modulation by

  13. VizieR Online Data Catalog: CoRoT observation log (N2-4.4) (CoRoT 2016)

    NASA Astrophysics Data System (ADS)

    COROT Team

    2014-03-01

    CoRoT, a space astronomy mission, has measured photometric micro-variability of stars from minutes to months (up to 150 days) with a high duty cycle (more than 90%). The mission was led by CNES in association with four French laboratories and 7 participating countries and agencies (Austria, Belgium, Brazil, Germany, Spain, and the ESA Science Programme). The satellite was composed of a PROTEUS platform (the 3rd in the series) and a unique instrument: a stellar rapid photometer. It was launched on December 27th 2006 by a Soyuz Rocket, from Bakonour. The mission has lasted almost 6 years (the nominal 3-year duration and a 3-year extension) and has observed more than 160 000 stars. It stopped sending data on November 2nd 2012. Two regions of the sky were accessible for long period of time: circles of 10 degrees centered on the equator around alpha=06:50 and alpha=18:50. They were called the CoRoT eyes: the "anticenter" and the "center eye" (as they are approximately in these directions). Each pointing covers 1.4x2.8 square degrees within one of those CoRoT eyes. The original scientific objectives were focussed on the study of stellar pulsations (asteroseismology) to probe the internal structure of stars, and the detection of small exoplanets through their "transiting in front of their host star, and the measurement of their size. This lead to introduce two modes of observations, working simultaneously: - The "bright star" mode dedicated to very precise seismology of a small sample of bright and closeby stars - The "faint star" mode, observing a very large number of stars at the same time, to detect transits, which are rare events, as they imply the alignment of the star, the planet and the observer. The large amount of data gathered in this mode turned out to be extremely fruitful for many topics of stellar physics. Beyond these two initial objectives, CoRoT data revealed stellar variability associated with various other phenomena: granulation, rotational modulation

  14. F Ring Core Stability: Corotation Resonance Plus Antiresonance

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeffrey N.; Marouf, Essam; French, Richard; Jacobson, Robert

    2014-01-01

    The decades-or-longer stability of the narrow F Ring core in a sea of orbital chaos appears to be due to an unusual combination of traditional corotation resonance and a novel kind of "antiresonance". At a series of specific locations in the F Ring region, apse precession between synodic encounters with Prometheus allows semimajor axis perturbations to promptly cancel before significant orbital period changes can occur. This cancellation fails for particles that encounter Prometheus when it is near its apoapse, especially during periods of antialignment of its apse with that of the F Ring. At these times, the strength of the semimajor axis perturbation is large (tens of km) and highly nonsinusoidal in encounter longitude, making it impossible to cancel promptly on a subsequent encounter and leading to chaotic orbital diffusion. Only particles that consistently encounter Prometheus away from its apoapse can use antiresonance to maintain stable orbits, implying that the true mean motion nF of the stable core must be defined by a corotational resonance of the form nF = nP(-kappa)P/m, where (nP, kappaP) are Prometheus' mean motion and epicycle frequency. To test this hypothesis we used the fact that Cassini RSS occultations only sporadically detect a "massive" F Ring core, composed of several-cm-and-larger particles. We regressed the inertial longitudes of 24 Cassini RSS (and VGR) detections and 43 nondetections to a common epoch, using a comb of candidate nP, and then folded them modulo the anticipated m-number of the corotational resonance (Prometheus m = 110 outer CER), to see if clustering appears. We find the "true F Ring core" is actually arranged in a series of short longitudinal arcs separated by nearly empty longitudes, orbiting at a well determined semimajor axis of 140222.4 km (from 2005-2012 at least). Small particles seen by imaging and stellar occultations spread quickly in azimuth and obscure this clumpy structure. Small chaotic variations in the mean

  15. F Ring Core Stability: Corotation Resonance Plus Antiresonance

    NASA Astrophysics Data System (ADS)

    Cuzzi, Jeffrey N.; Marouf, Essam; French, Richard; Jacobson, Robert

    2014-11-01

    The decades-or-longer stability of the narrow F Ring core in a sea of orbital chaos appears to be due to an unusual combination of traditional corotation resonance and a novel kind of “antiresonance”. At a series of specific locations in the F Ring region, apse precession between synodic encounters with Prometheus allows semimajor axis perturbations to promptly cancel before significant orbital period changes can occur (Cuzzi et al. 2014, Icarus 232, 157-175). This cancellation fails for particles that encounter Prometheus when it is near its apoapse, especially during periods of antialignment of its apse with that of the F Ring. At these times, the strength of the semimajor axis perturbation is large (tens of km) and highly nonsinusoidal in encounter longitude, making it impossible to cancel promptly on a subsequent encounter and leading to chaotic orbital diffusion. Only particles that consistently encounter Prometheus away from its apoapse can use antiresonance to maintain stable orbits, implying that the true mean motion nF of the stable core must be defined by a corotational resonance of the form nF = nP-κP/m, where (nP, κP) are Prometheus’ mean motion and epicycle frequency. To test this hypothesis we used the fact that Cassini RSS occultations only sporadically detect a “massive” F Ring core, composed of several-cm-and-larger particles. We regressed the inertial longitudes of 24 Cassini RSS (and VGR) detections and 43 nondetections to a common epoch, using a comb of candidate nP, and then folded them modulo the anticipated m-number of the corotational resonance (Prometheus m=110 outer CER), to see if clustering appears. We find the “true F Ring core” is actually arranged in a series of short longitudinal arcs separated by nearly empty longitudes, orbiting at a well determined semimajor axis of 140222.4km (from 2005-2012 at least). Small particles seen by imaging and stellar occultations spread quickly in azimuth and obscure this clumpy

  16. Evolution of binary black holes in self gravitating discs. Dissecting the torques

    NASA Astrophysics Data System (ADS)

    Roedig, C.; Sesana, A.; Dotti, M.; Cuadra, J.; Amaro-Seoane, P.; Haardt, F.

    2012-09-01

    Context. Massive black hole binaries, formed in galaxy mergers, are expected to evolve in dense circumbinary discs. Understanding of the disc-binary coupled dynamics is vital to assess both the final fate of the system and its potentially observable features. Aims: Aimed at understanding the physical roots of the secular evolution of the binary, we study the interplay between gas accretion and gravity torques in changing the binary elements (semi-major axis and eccentricity) and its total angular momentum budget. We pay special attention to the gravity torques, by analysing their physical origin and location within the disc. Methods: We analysed three-dimensional smoothed particle hydrodynamics simulations of the evolution of initially quasi-circular massive black hole binaries (BHBs) residing in the central hollow (cavity) of massive self-gravitating circumbinary discs. We performed a set of simulations adopting different thermodynamics for the gas within the cavity and for the "numerical size" of the black holes. Results: We show that (i) the BHB eccentricity growth found in our previous work is a general result, independent of the accretion and the adopted thermodynamics; (ii) the semi-major axis decay depends not only on the gravity torques but also on their subtle interplay with the disc-binary angular momentum transfer due to accretion; (iii) the spectral structure of the gravity torques is predominately caused by disc edge overdensities and spiral arms developing in the body of the disc and, in general, does not reflect directly the period of the binary; (iv) the net gravity torque changes sign across the BHB corotation radius (positive inside vs negative outside) We quantify the relative importance of the two, which appear to depend on the thermodynamical properties of the instreaming gas, and which is crucial in assessing the disc-binary angular momentum transfer; (v) the net torque manifests as a purely kinematic (non-resonant) effect as it stems from the

  17. 14 CFR 29.361 - Engine torque.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 29.361 Engine torque. The... malfunction or structural failure (such as compressor jamming). (b) For reciprocating engines, the mean torque... and System Loads...

  18. 14 CFR 29.361 - Engine torque.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 29.361 Engine torque. The... malfunction or structural failure (such as compressor jamming). (b) For reciprocating engines, the mean torque... and System Loads...

  19. 14 CFR 29.361 - Engine torque.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 29.361 Engine torque. The... malfunction or structural failure (such as compressor jamming). (b) For reciprocating engines, the mean torque... and System Loads...

  20. 14 CFR 29.361 - Engine torque.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 29.361 Engine torque. The... malfunction or structural failure (such as compressor jamming). (b) For reciprocating engines, the mean torque... and System Loads...

  1. 14 CFR 29.361 - Engine torque.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 29.361 Engine torque. The... malfunction or structural failure (such as compressor jamming). (b) For reciprocating engines, the mean torque... and System Loads...

  2. Power Tool Would Require Little Bracing Torque

    NASA Technical Reports Server (NTRS)

    Canniff, Joseph H.

    1995-01-01

    Proposed rotary power tool exerts required torque on workpiece, but little or no bracing torque applied to tool to keep it from turning in opposite direction. Instead, working torque neutralized by nearly equal and opposite torque generated within tool. Used easily underwater, on slippery surfaces, or in other environments in which external bracing of tool against rotation difficult or impossible. Minimizes armbreaking forces resulting from tool binding.

  3. Ionospheric storms on Mars: Impact of the corotating interaction region

    NASA Astrophysics Data System (ADS)

    Dubinin, E.; Fraenz, M.; Woch, J.; Duru, F.; Gurnett, D.; Modolo, R.; Barabash, S.; Lundin, R.

    2009-01-01

    Measurements made by the ASPERA-3 and MARSIS experiments on Mars Express have shown, for the first time, that space weather effects related to the impact of a dense and high pressure solar wind (corotating interaction region) on Mars cause strong perturbations in the martian induced magnetosphere and ionosphere. The magnetic barrier formed by pile-up of the draped interplanetary magnetic field ceases to be a shield for the incoming solar wind. Large blobs of solar wind plasma penetrate to the magnetosphere and sweep out dense plasma from the ionosphere. The topside martian ionosphere becomes very fragmented consisting of intermittent cold/low energy and energized plasmas. The scavenging effect caused by the intrusions of solar wind plasma clouds enhances significantly (by a factor of >=10) the losses of volatile material from Mars.

  4. Effects of corotating interaction regions on ULYSSES high energy particles

    SciTech Connect

    Droege, W.; Kunow, H.; Raviart, A.

    1995-09-01

    Since June 1992 the Kiel Electron Telescope on board ULYSSES measures variations of more than 10% in the fluxes of high energy H and He showing a periodicity of about 26 days in coincidence with the passage of corotating interaction regions. (CIR). At low energies MeV protons are accelerated at the shocks of the CIRs. These effects are observed up to high southern latitudes, where the signature of a CIR is no longer visible in plasma or magnetic field data. After passing over the south polar cap ULYSSES has now returned to the solar equator and climbs up to the north pole. In this paper we study the relative intensity variations with latitude and the latitude dependence at solar distances smaller than ever studied before.

  5. Corotation lag of Saturn's magnetosphere - Global ionospheric conductivities revisited

    NASA Astrophysics Data System (ADS)

    Cheng, A. F.; Waite, J. H.

    1988-05-01

    In view of the recent publication of Eviatar and Richardson (1986), who have calculated the Pedersen conductance of Saturn's ionosphere to be much smaller than previous estimates, the Pedersen conductance is recalculated using the same neutral atmosphere model as these authors. The results confirm the earlier estimates that the ionospheric Pedersen conductance of Saturn's ionosphere ranges from 0.3 to 17 mho near the terminator as a function of latitude. The source of discrepancy appears to be the inclusion by Eviatar and Richardson of ion density into the ion-neutral collision frequency term, which is incorrect. Contrary to the conclusion of Eviatar and Richardson, Saturn's ionospheric Pedersen conductance is high enough to impose nearly perfect corotation between the ionosphere and the magnetosphere.

  6. 40 CFR 1065.310 - Torque calibration.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... ENGINE-TESTING PROCEDURES Calibrations and Verifications Measurement of Engine Parameters and Ambient Conditions § 1065.310 Torque calibration. (a) Scope and frequency. Calibrate all torque-measurement systems including dynamometer torque measurement transducers and systems upon initial installation and after...

  7. Computerized Torque Control for Large dc Motors

    NASA Technical Reports Server (NTRS)

    Willett, Richard M.; Carroll, Michael J.; Geiger, Ronald V.

    1987-01-01

    Speed and torque ranges in generator mode extended. System of shunt resistors, electronic switches, and pulse-width modulation controls torque exerted by large, three-phase, electronically commutated dc motor. Particularly useful for motor operating in generator mode because it extends operating range to low torque and high speed.

  8. Stochastic gravito-inertial modes discovered by CoRoT in the hot Be star HD 51452

    NASA Astrophysics Data System (ADS)

    Neiner, C.; Floquet, M.; Samadi, R.; Espinosa Lara, F.; Frémat, Y.; Mathis, S.; Leroy, B.; de Batz, B.; Rainer, M.; Poretti, E.; Mathias, P.; Guarro Fló, J.; Buil, C.; Ribeiro, J.; Alecian, E.; Andrade, L.; Briquet, M.; Diago, P. D.; Emilio, M.; Fabregat, J.; Gutiérrez-Soto, J.; Hubert, A.-M.; Janot-Pacheco, E.; Martayan, C.; Semaan, T.; Suso, J.; Zorec, J.

    2012-10-01

    Context. Be stars are rapidly rotating stars with a circumstellar decretion disk. They usually undergo pressure and/or gravity pulsation modes excited by the κ-mechanism, i.e. an effect of the opacity of iron-peak elements in the envelope of the star. In the Milky Way, p-modes are observed in stars that are hotter than or equal to the B3 spectral type, while g-modes are observed at the B2 spectral type and cooler. Aims: We observed a B0IVe star, HD 51452, with the high-precision, high-cadence photometric CoRoT satellite and high-resolution, ground-based HARPS and SOPHIE spectrographs to study its pulsations in great detail. We also used the lower resolution spectra available in the BeSS database. Methods: We analyzed the CoRoT and spectroscopic data with several methods: Clean-NG, FreqFind, and a sliding window method. We also analyzed spectral quantities, such as the violet over red (V/R) emission variations, to obtain information about the variation in the circumstellar environment. We calculated a stellar structure model with the ESTER code to test the various interpretation of the results. Results: We detect 189 frequencies of variations in the CoRoT light curve in the range between 0 and 4.5 c d-1. The main frequencies are also recovered in the spectroscopic data. In particular we find that HD 51452 undergoes gravito-inertial modes that are not in the domain of those excited by the κ-mechanism. We propose that these are stochastic modes excited in the convective zones and that at least some of them are a multiplet of r-modes (i.e. subinertial modes mainly driven by the Coriolis acceleration). Stochastically excited gravito-inertial modes had never been observed in any star, and theory predicted that their very low amplitudes would be undetectable even with CoRoT. We suggest that the amplitudes are enhanced in HD 51452 because of the very rapid stellar rotation. In addition, we find that the amplitude variations of these modes are related to the occurrence of

  9. Positional Dependent Driving Torque in the Damped, Driven Pendulum

    NASA Astrophysics Data System (ADS)

    McAlpine, Todd; Huff, Alison

    2009-04-01

    We investigate the dynamics of a plane pendulum with positional dependent driving torque as would be produced by a horizontally directed force exerted on the pendulum bob. We compare this with the well known dynamics of a standard damped, driven plane pendulum. In particular we compare the bifurcation diagrams of the two systems to compare the effects of the driving amplitude on the dynamics. In the system with positional dependent driving torque, bifurcation begins at higher driving amplitudes and there is a repetitive structure in the bifurcation diagram at high driving amplitude. Additionally, with positional dependent driving torque we see continued chaotic behavior at high driving amplitude whereas the chaotic behavior of the standard pendulum dies out at large driving amplitudes.

  10. Application of the TRUFAS detection algorithm to the first two runs of CoRoT

    NASA Astrophysics Data System (ADS)

    Régulo, Clara; Almenara, Jose M.; Deeg, Hans J.

    2009-02-01

    TRUFAS is a wavelet-based algorithm developed for the rapid detection of planetary transits in the frame of the COROT space mission. We present the application of this algorithm to the first two observing fields of CoRoT data. In these, CoRoT has observed a total of about 20000 stars. The first CoRoT observing run, IRa01, covers 2 months, February and March 2007, followed by the 5-months long run LRc01. TRUFAS is a very fast algorithm delivering reliable detections. Here we show the results when TRUFAS was applied to these first two sets of data. In the first run, IRa01, TRUFAS found 10 planet candidates and 143 eclipsing binaries and in the LRc01 10 planet candidates and 124 binaries, with a processing that lasted only one night.

  11. Low-Torque Seal Development

    NASA Technical Reports Server (NTRS)

    Lattime, Scott B.; Borowski, Richard

    2009-01-01

    The EcoTurn Class K production prototypes have passed all AAR qualification tests and received conditional approval. The accelerated life test on the second set of seals is in progress. Due to the performance of the first set, no problems are expected.The seal has demonstrated superior performance over the HDL seal in the test lab with virtually zero torque and excellent contamination exclusion and grease retention.

  12. Space Suit Joint Torque Testing

    NASA Technical Reports Server (NTRS)

    Valish, Dana J.

    2011-01-01

    In 2009 and early 2010, a test was performed to quantify the torque required to manipulate joints in several existing operational and prototype space suits in an effort to develop joint torque requirements appropriate for a new Constellation Program space suit system. The same test method was levied on the Constellation space suit contractors to verify that their suit design meets the requirements. However, because the original test was set up and conducted by a single test operator there was some question as to whether this method was repeatable enough to be considered a standard verification method for Constellation or other future space suits. In order to validate the method itself, a representative subset of the previous test was repeated, using the same information that would be available to space suit contractors, but set up and conducted by someone not familiar with the previous test. The resultant data was compared using graphical and statistical analysis and a variance in torque values for some of the tested joints was apparent. Potential variables that could have affected the data were identified and re-testing was conducted in an attempt to eliminate these variables. The results of the retest will be used to determine if further testing and modification is necessary before the method can be validated.

  13. Radiative Torques: Analytical Model And Basic Properties

    NASA Astrophysics Data System (ADS)

    Hoang, Thiem; Lazarian, A.

    2007-05-01

    We attempt to get a physical insight into grain alignment processes by studying basic properties of radiative torques (RATs). For this purpose we consider a simple toy model of a helical grain that reproduces well the basic features of RATs. The model grain consists of a reflecting spheroidal body with a reflecting mirror attached at an angle to it. Being very simple, the model allows analytical description of RATs that act upon it. We show a good correspondence of RATs obtained for this model and those of irregular grains calculated by DDSCAT. Our analysis of the role of different torque components for grain alignment reveals that one of the three RAT components does not affect the alignment, but induces only for grain precession. The other two components provide a generic alignment with grain long axes perpendicular to the light radiation, if the radiation dominates the grain precession, and perpendicular to magnetic field, otherwise. The latter coincides with the famous predictions of the Davis-Greenstein process, but our model does not invoke paramagnetic relaxation. In addition, we find that a substantial part of grains subjected to RATs gets aligned with low angular momentum, which testifies, that most of the grains in diffuse interstellar medium do not rotate fast, i.e. rotate with thermal or even sub-thermal velocities. For the radiation-dominated environments, we find that the alignment can take place on the time scale much shorter than the time of gaseous damping of grain rotation.

  14. CoRoT-7b: SUPER-EARTH OR SUPER-Io?

    SciTech Connect

    Barnes, Rory; Kaib, Nathan A.; Raymond, Sean N.; Greenberg, Richard; Jackson, Brian

    2010-02-01

    CoRoT-7b, a planet about 70% larger than the Earth orbiting a Sun-like star, is the first-discovered rocky exoplanet, and hence has been dubbed a 'super-Earth'. Some initial studies suggested that since the planet is so close to its host star, it receives enough insolation to partially melt its surface. However, these past studies failed to take into consideration the role that tides may play in this system. Even if the planet's eccentricity has always been zero, we show that tidal decay of the semimajor axis could have been large enough that the planet formed on a wider orbit which received less insolation. Moreover, CoRoT-7b could be tidally heated at a rate that dominates its geophysics and drives extreme volcanism. In this case, CoRoT-7b is a 'super-Io' that, like Jupiter's volcanic moon, is dominated by volcanism and rapid resurfacing. Such heating could occur with an eccentricity of just 10{sup -5}. This small value could be driven by CoRoT-7c if its own eccentricity is larger than {approx}10{sup -4}. CoRoT-7b may be the first of a class of planetary super-Ios likely to be revealed by the CoRoT and Kepler spacecraft.

  15. Torque coordinating robust control of shifting process for dry dual clutch transmission equipped in a hybrid car

    NASA Astrophysics Data System (ADS)

    Zhao, Z.-G.; Chen, H.-J.; Yang, Y.-Y.; He, L.

    2015-09-01

    For a hybrid car equipped with dual clutch transmission (DCT), the coordination control problems of clutches and power sources are investigated while taking full advantage of the integrated starter generator motor's fast response speed and high accuracy (speed and torque). First, a dynamic model of the shifting process is established, the vehicle acceleration is quantified according to the intentions of the driver, and the torque transmitted by clutches is calculated based on the designed disengaging principle during the torque phase. Next, a robust H∞ controller is designed to ensure speed synchronisation despite the existence of model uncertainties, measurement noise, and engine torque lag. The engine torque lag and measurement noise are used as external disturbances to initially modify the output torque of the power source. Additionally, during the torque switch phase, the torque of the power sources is smoothly transitioned to the driver's demanded torque. Finally, the torque of the power sources is further distributed based on the optimisation of system efficiency, and the throttle opening of the engine is constrained to avoid sharp torque variations. The simulation results verify that the proposed control strategies effectively address the problem of coordinating control of clutches and power sources, establishing a foundation for the application of DCT in hybrid cars.

  16. Diverse high-torque bacterial flagellar motors assemble wider stator rings using a conserved protein scaffold.

    PubMed

    Beeby, Morgan; Ribardo, Deborah A; Brennan, Caitlin A; Ruby, Edward G; Jensen, Grant J; Hendrixson, David R

    2016-03-29

    Although it is known that diverse bacterial flagellar motors produce different torques, the mechanism underlying torque variation is unknown. To understand this difference better, we combined genetic analyses with electron cryo-tomography subtomogram averaging to determine in situ structures of flagellar motors that produce different torques, from Campylobacter and Vibrio species. For the first time, to our knowledge, our results unambiguously locate the torque-generating stator complexes and show that diverse high-torque motors use variants of an ancestrally related family of structures to scaffold incorporation of additional stator complexes at wider radii from the axial driveshaft than in the model enteric motor. We identify the protein components of these additional scaffold structures and elucidate their sequential assembly, demonstrating that they are required for stator-complex incorporation. These proteins are widespread, suggesting that different bacteria have tailored torques to specific environments by scaffolding alternative stator placement and number. Our results quantitatively account for different motor torques, complete the assignment of the locations of the major flagellar components, and provide crucial constraints for understanding mechanisms of torque generation and the evolution of multiprotein complexes. PMID:26976588

  17. Diverse high-torque bacterial flagellar motors assemble wider stator rings using a conserved protein scaffold

    PubMed Central

    Ribardo, Deborah A.; Brennan, Caitlin A.; Ruby, Edward G.; Jensen, Grant J.; Hendrixson, David R.

    2016-01-01

    Although it is known that diverse bacterial flagellar motors produce different torques, the mechanism underlying torque variation is unknown. To understand this difference better, we combined genetic analyses with electron cryo-tomography subtomogram averaging to determine in situ structures of flagellar motors that produce different torques, from Campylobacter and Vibrio species. For the first time, to our knowledge, our results unambiguously locate the torque-generating stator complexes and show that diverse high-torque motors use variants of an ancestrally related family of structures to scaffold incorporation of additional stator complexes at wider radii from the axial driveshaft than in the model enteric motor. We identify the protein components of these additional scaffold structures and elucidate their sequential assembly, demonstrating that they are required for stator-complex incorporation. These proteins are widespread, suggesting that different bacteria have tailored torques to specific environments by scaffolding alternative stator placement and number. Our results quantitatively account for different motor torques, complete the assignment of the locations of the major flagellar components, and provide crucial constraints for understanding mechanisms of torque generation and the evolution of multiprotein complexes. PMID:26976588

  18. GROUND-BASED DETECTIONS OF THERMAL EMISSION FROM CoRoT-1b AND WASP-12b

    SciTech Connect

    Zhao Ming; Swain, Mark R.; Monnier, John D.; Barman, Travis; Hinkley, Sasha

    2012-01-10

    We report a new detection of the H-band thermal emission of CoRoT-1b and two confirmation detections of the Ks-band thermal emission of WASP-12b at secondary eclipses. The H-band measurement of CoRoT-1b shows an eclipse depth of 0.145% {+-} 0.049% with a 3{sigma} percentile between 0.033% and 0.235%. This depth is consistent with the previous conclusions that the planet has an isothermal region with inefficient heat transport from day side to night side, and has a dayside thermal inversion layer at high altitude. The two Ks-band detections of WASP-12b show a joint eclipse depth of 0.299% {+-} 0.065%. This result agrees with the measurement of Croll and collaborators, providing independent confirmation of their measurement. The repeatability of the WASP-12b measurements also validates our data analysis method. Our measurements, in addition to a number of previous results made with other telescopes, demonstrate that ground-based observations are becoming widely available for characterization of atmospheres of hot Jupiters.

  19. Inertia-gravity wave radiation from the merging of two co-rotating vortices in the f-plane shallow water system

    SciTech Connect

    Sugimoto, Norihiko

    2015-12-15

    Inertia-gravity wave radiation from the merging of two co-rotating vortices is investigated numerically in a rotating shallow water system in order to focus on cyclone–anticyclone asymmetry at different values of the Rossby number (Ro). A numerical study is conducted on a model using a spectral method in an unbounded domain to estimate the gravity wave flux with high accuracy. Continuous gravity wave radiation is observed in three stages of vortical flows: co-rotating of the vortices, merging of the vortices, and unsteady motion of the merged vortex. A cyclone–anticyclone asymmetry appears at all stages at smaller Ro (≤20). Gravity waves from anticyclones are always larger than those from cyclones and have a local maximum at smaller Ro (∼2) compared with that for an idealized case of a co-rotating vortex pair with a constant rotation rate. The source originating in the Coriolis acceleration has a key role in cyclone–anticyclone asymmetry in gravity waves. An additional important factor is that at later stages, the merged axisymmetric anticyclone rotates faster than the elliptical cyclone due to the effect of the Rossby deformation radius, since a rotation rate higher than the inertial cutoff frequency is required to radiate gravity waves.

  20. Larger plantar flexion torque variability implies less stable balance in the young: an association affected by knee position.

    PubMed

    Mello, Emanuele Moraes; Magalhães, Fernando Henrique; Kohn, André Fabio

    2013-12-01

    The present study examined the association between plantar flexion torque variability during isolated isometric contractions and during quiet bipedal standing. For plantar flexion torque measurements in quiet stance (QS), subjects stood still over a force plate. The mean plantar flexion torque level exerted by each subject in QS (divided by 2 to give the torque due to a single leg) served as the target torque level for right leg force-matching tasks in extended knee (KE) and flexed knee (KF) conditions. Muscle activation levels (EMG amplitudes) of the triceps surae and mean, standard deviation and coefficient of variation of plantar flexion torque were computed from signals acquired during periods with and without visual feedback. No significant correlations were found between EMG amplitudes and torque variability, regardless of the condition and muscle being analyzed. A significant correlation was found between torque variability in QS and KE, whereas no significant correlation was found between torque variability in QS and KF, regardless of vision availability. Therefore, torque variability measured in a controlled extended knee plantar flexion contraction is a predictor of torque variability in the anterior-posterior direction when the subjects are in quiet standing. In other words, larger plantar flexion torque variability in KE (but not in KF) implies less stable balance. The mechanisms underlying the findings above are probably associated with the similar proprioceptive feedback from the triceps surae in QS and KE and poorer proprioceptive feedback from the triceps surae in KF due to the slackening of the gastrocnemii. An additional putative mechanism includes the different torque contributions of each component of the triceps surae in the two knee angles. From a clinical and research standpoint, it would be advantageous to be able to estimate changes in balance ability by means of simple measurements of torque variability in a force matching task.

  1. The role of interaction torque and muscle torque in the control of downward squatting

    PubMed Central

    Fujisawa, Hiroyuki; Suzuki, Hiroto; Murakami, Kenichi; Kawakami, Shingo; Suzuki, Makoto

    2016-01-01

    [Purpose] The purposes of this study were first to analyze the multijoint dynamics of downward squatting, and to examine the contribution of interaction torque and muscle torque to net torque, and second, to examine mechanisms of movement control. [Subjects] The subjects were 31 healthy men with a mean age of 21.0 ± 1.2 years (range, 19–24 years). [Methods] Squatting tasks with the trunk in two positions, an erect and anterior tilt position, were performed by the subjects. Net, interaction, muscle, and gravity torque were calculated according to the Lagrange equation using 3D tracking data. [Results] The contribution ratio of interaction torque to net torque was approximately 90%, irrespective of the joint and task. In contrast, muscle torque showed complicated behavior to compensate for gravity torque. A combined muscle and gravity torque profile showed flexion or dorsiflexion immediately after the initiation of the movement, and it later changed to extension or plantar flexion. [Conclusion] The torque that contributes almost exclusively to the net torque was interaction torque. The combination of muscle and gravity torque at the knee joint and the hip joint is important for movement control, independent of the starting position. PMID:27065552

  2. The role of interaction torque and muscle torque in the control of downward squatting.

    PubMed

    Fujisawa, Hiroyuki; Suzuki, Hiroto; Murakami, Kenichi; Kawakami, Shingo; Suzuki, Makoto

    2016-01-01

    [Purpose] The purposes of this study were first to analyze the multijoint dynamics of downward squatting, and to examine the contribution of interaction torque and muscle torque to net torque, and second, to examine mechanisms of movement control. [Subjects] The subjects were 31 healthy men with a mean age of 21.0 ± 1.2 years (range, 19-24 years). [Methods] Squatting tasks with the trunk in two positions, an erect and anterior tilt position, were performed by the subjects. Net, interaction, muscle, and gravity torque were calculated according to the Lagrange equation using 3D tracking data. [Results] The contribution ratio of interaction torque to net torque was approximately 90%, irrespective of the joint and task. In contrast, muscle torque showed complicated behavior to compensate for gravity torque. A combined muscle and gravity torque profile showed flexion or dorsiflexion immediately after the initiation of the movement, and it later changed to extension or plantar flexion. [Conclusion] The torque that contributes almost exclusively to the net torque was interaction torque. The combination of muscle and gravity torque at the knee joint and the hip joint is important for movement control, independent of the starting position. PMID:27065552

  3. Suprathermal helium associated with corotating interaction regions: A case study

    NASA Astrophysics Data System (ADS)

    Yu, J.; Berger, L.; Wimmer-Schweingruber, R. F.; Hilchenbach, M.; Kallenbach, R.; Klecker, B.; Guo, J.

    2016-03-01

    Enhancements of suprathermal particles observed at 1AU often can be related to Corotating Interaction Regions (CIRs). The compression regions associated with CIRs and their driven shocks which typically form at a few AU distance to the Sun can efficiently accelerate particles. If accelerated at the trailing edge of a CIR these particles can travel sunward along the ambient magnetic field and thus enhanced fluxes can be observed even if the acceleration region has passed over the spacecraft. We have analysed a CIR that has been observed at L1 by ACE/SWICS and SOHO/CELIAS/STOF on days 207 and 208 in 2003. The combination of SWICS and STOF data allowed us to study suprathermal Helium ranging from its onset at solar wind bulk energies up to 330 keV/nuc. Here we present our results for the temporal evolution of the flux, energy spectra and the He+/He++ ratio. In particular we present observational evidence for a turnover of the energy spectra at lower energies after the CIR passage which has been theoretically predicted but never been observed so far.

  4. HELIUM ION ANISOTROPIES IN COROTATING INTERACTION REGIONS AT 1 AU

    SciTech Connect

    Ebert, R. W.; Desai, M. I.; Dayeh, M. A.; Mason, G. M.

    2012-08-01

    We investigated the first-order flow anisotropies in the solar wind frame of {approx}0.06-0.95 MeV nucleon{sup -1} He ions during three corotating interaction region (CIR)-associated particle intensity enhancements observed at 1 AU by Wind, examining CIRs with (1) a reverse shock, (2) a well-formed compression region, and (3) a weak compression region. We identified anti-sunward flows in the compression region downstream of the CIR trailing edge in the events with a reverse shock and well-formed compression that transitioned to sunward flows across and upstream of this boundary. These observations suggest that the trailing edge is organizing the He ion flows and is a local source for the particles in these events, this source being inside 1 AU prior to the trailing edge arrival and beyond 1 AU after its passage. The event with the weak compression region had predominantly sunward flows throughout, indicating that the source of the He ions was beyond 1 AU. These observations provide compelling evidence that He ions at 1 AU can be accelerated to suprathermal energies at the CIR trailing edge in events where the compression region is well formed.

  5. Effects of corotating interaction regions on Ulysses high energy particles

    SciTech Connect

    Droege, W.; Kunow, H.; Heber, B.; Mueller-Mellin, R.; Sierks, H.; Wibberenz, G.; Raviart, A.; Ducros, R.; Ferrando, P.; Rastoin, C.; Paizis, C.; Gosling, J. T.

    1996-07-20

    We investigate the intensity variation of low energy ({approx}6-23 MeV/N) heliospheric ions and of galactic protons (250-2200 MeV) observed by the Kiel Electron Telescope onboard the Ulysses spacecraft associated with Corotating Interaction Regions (CIR) from mid-1992 to end of June 1995. This period covers Ulysses' transit to high southern latitudes, the south polar pass, return to the solar equator and ascent to the north pole up to 70 deg. We find that the flux of high energy protons exhibits a periodicity of about 26 days with a relative intensity variation of 10%. At latitudes below {approx}50 deg. the recurrent variations of galactic protons are in coincidence with the passage of CIRs and enhancements of low energies protons and alpha particles which are accelerated at the shocks of the CIRs. The modulation of galactic protons is observed up to high southern latitudes, where the signatures of a CIR are no longer visible in plasma or magnetic field data. The periodicity does not depend on latitude and its phase apparently remains constant during Ulysses' pass over the south pole as well as through the solar equator.

  6. Effects of corotating interaction regions on Ulysses high energy particles

    SciTech Connect

    Droege, W.; Kunow, H.; Heber, B.; Mueller-Mellin, R.; Sierks, H.; Wibberenz, G.; Raviart, A.; Ducros, R.; Ferrando, P.; Rastoin, C.; Gosling, J.T.

    1996-07-01

    We investigate the intensity variation of low energy ({approximately}6{endash}23MeV/N) heliospheric ions and of galactic protons (250{endash}2200 MeV) observed by the Kiel Electron Telescope onboard the Ulysses spacecraft associated with Corotating Interaction Regions (CIR) from mid-1992 to end of June 1995. This period covers Ulysses{close_quote} transit to high southern latitudes, the south polar pass, return to the solar equator and ascent to the north pole up to 70{degree}. We find that the flux of high energy protons exhibits a periodicity of about 26 days with a relative intensity variation of 10{percent}. At latitudes below {approximately}50{degree} the recurrent variations of galactic protons are in coincidence with the passage of CIRs and enhancements of low energies protons and alpha particles which are accelerated at the shocks of the CIRs. The modulation of galactic protons is observed up to high southern latitudes, where the signatures of a CIR are no longer visible in plasma or magnetic field data. The periodicity does not depend on latitude and its phase apparently remains constant during Ulysses{close_quote} pass over the south pole as well as through the solar equator. {copyright} {ital 1996 American Institute of Physics.}

  7. Corotating particle enhancements out of the ecliptic plane

    NASA Technical Reports Server (NTRS)

    Simnett, G. M.; Sayle, K.; Roelof, E. C.; Tappin, S. J.

    1994-01-01

    We have studied greater than 40 keV ion and electron enhancements seen at Ulysses from a series of corotating interaction regions (CIR), from mid-1992 until the end of 1993. The event intensity increased up to latitude 20 deg S; after that the ion flux maxima decreased by approximately 23%/deg while the electron maxima decreased more erratically, and more slowly, during the last half of 1993. After April, 1993, the electron increases lagged the ions by up to four days. The electron energy spectrum hardened both towards the end of the events and as the latitude went above approximately 35 deg. The electron/ion delays and the electron spectral hardening are related to the three-dimensional structure of the reverse shocks at high latitudes. The H/He ratio at approximately 0.4-1.2 MeV/nucleon decreased towards the end of each event; the mean minimum value was 3.5 +/- 0.3, lower than observed in earlier studies of CIR-associated events near the ecliptic plane. The He increases have recurred with a period of 26.0 days. There have been two phase changes: +4.3 days (February 1993) and +2.4 days (August 1993), related to changes in the coronal structure of the source regions for the high speed solar wind streams.

  8. Investigation of Motorcycle Steering Torque Components

    NASA Astrophysics Data System (ADS)

    Cossalter, V.; Lot, R.; Massaro, M.; Peretto, M.

    2011-10-01

    When driving along a circular path, the rider controls a motorcycle mainly by the steering torque. This work addresses an in-depth analysis of the steady state cornering and in particular the decomposition of the motorcycle steering torque in its main components, such as road-tyre forces, gyroscopic torques, centrifugal and gravity effects. A detailed and experimentally validated multibody model of the motorcycle is used herein to analyze the steering torque components at different speeds and lateral accelerations. First the road tests are compared with the numerical results for three different vehicles and then a numerical investigation is carried out to decompose the steering torque. Finally, the effect of longitudinal acceleration and deceleration on steering torque components is presented.

  9. Magnetic field control. [electromechanical torquing device

    NASA Technical Reports Server (NTRS)

    Haeussermann, W. (Inventor)

    1982-01-01

    A torque control for an electromechanical torquing device of a type where a variable clearance occurs between a rotor and field is described. A Hall effect device senses the field present, which would vary as a function of spacing between field and rotor. The output of the Hall effect device controls the power applied to the field so as to provide a well defined field and thus a controlled torque to the rotor which is well defined.

  10. Integrated Design of an Active Torque Balancing Mechanism and a Planetary Gear Reducer

    NASA Astrophysics Data System (ADS)

    Sun, Jing; Yao, Yanan

    In this paper, a novel concept of integrating an active torque balancing mechanism with a planetary gear reducer is presented. This integrated device is composed of a speed reduction unit and a torque compensation unit. The speed reduction unit, which contains a two-stage planetary gear train, can make the device to transform the speed and torque for meeting the needed requirements of the machine. The torque compensation unit, which consists of a differential gear train and a servo motor, can make the device to balance the input torque fluctuations of the mechanical system. Through an analytical method, an exact control function which can totally eliminate the input torque fluctuation of the driving motor of the machine is derived for the servo motor of the integrated device. At the same time, by adjusting the structure parameters of the differential gear train, the torque fluctuation of the servo motor can be limited too. Besides, in order to obtain a satisfactory tradeoff between the torque fluctuations of the driving motor and the servo motor, an optimization method is developed to find an appropriate control function for the servo motor. In addition, an integrated approach is proposed to optimize both the structure parameters of the differential gear train and the control function of the servo motor. Two numerical examples are given to illustrate the design procedures and to show their feasibilities.

  11. Spin-Orbit Torques and Anisotropic Magnetization Damping in Skyrmion Crystals

    NASA Astrophysics Data System (ADS)

    Hals, Kjetil; Brataas, Arne

    2014-03-01

    We theoretically study the effects of reactive and dissipative homogeneous spin-orbit torques and anisotropic damping on the current-driven skyrmion dynamics in cubic chiral magnets. Our results demonstrate that spin-orbit torques play a significant role in the current-induced skyrmion velocity. The dissipative spin-orbit torque generates a relativistic Magnus force on the skyrmions, whereas the reactive spin-orbit torque yields a correction to both the drift velocity along the current direction and the transverse velocity associated with the Magnus force. The spin-orbit torque corrections to the velocity scale linearly with the skyrmion size, which is inversely proportional to the spin-orbit coupling. Consequently, the reactive spin-orbit torque correction can be the same order of magnitude as the non-relativistic contribution. More importantly, the dissipative spin-orbit torque can be the dominant force that causes a deflected motion of the skyrmions if the torque exhibits a linear or quadratic relationship with the spin-orbit coupling. In addition, we demonstrate that the skyrmion velocity is determined by anisotropic magnetization damping parameters governed by the skyrmion size.

  12. Torque limited drive for manual valves

    DOEpatents

    Elliott, Philip G.; Underwood, Daniel E.

    1989-01-01

    The present invention is directed to a torque-limiting handwheel device for preventing manual valves from being damaged due to the application of excessive torque during the opening or closing operation of the valves. Torque can only be applied when ridges in the handwheel assembly engage in channels machined in the face of the baseplate. The amount of torque required for disengagement of the ridges from the channels is determined by the force exerted by various Bellville springs and the inclination of the side faces of the channels.

  13. Torque limited drive for manual valves

    DOEpatents

    Elliott, Philip G.; Underwood, Daniel E.

    1989-06-06

    The present invention is directed to a torque-limiting handwheel device for preventing manual valves from being damaged due to the application of excessive torque during the opening or closing operation of the valves. Torque can only be applied when ridges in the handwheel assembly engage in channels machined in the face of the baseplate. The amount of torque required for disengagement of the ridges from the channels is determined by the force exerted by various Bellville springs and the inclination of the side faces of the channels.

  14. Modeling interstellar pickup ion distributions in corotating interaction regions inside 1 AU

    NASA Astrophysics Data System (ADS)

    Chen, J. H.; Schwadron, N. A.; Möbius, E.; Gorby, M.

    2015-11-01

    We present a modeling study of interstellar pickup ion (PUI) distributions in corotating interaction regions (CIRs). We consider gradual compressions associated with CIRs formed when fast speed streams overtake slower streams in the inner heliosphere. For the analysis, we adopt a simplified magnetohydrodynamic model of a CIR. The Energetic Particle Radiation Environment Module, a parallelized particle numerical kinetic code, is used to model PUI distributions using the focused transport equation, including adiabatic cooling/heating, adiabatic focusing, and parallel and perpendicular diffusion. The continuous injection of PUIs is handled as a source term with a ring distribution in velocity space that is produced from the local neutral density obtained from a hot model of the interstellar neutral gas. The simulated distributions exhibit a harder spectrum in the compression region and a softer spectrum in the rarefaction region than that in undisturbed solar wind. As an additional result, a v-5 power law tail distribution above the PUI cutoff speed (a knee in the distribution) emerges for a particular velocity gradient in the CIR. The tail above the PUI cutoff is sensitive to the CIR velocity gradient, and in one observational case studied, this relationship adequately explains the observed spectrum from 2 to 4 times the solar wind speed. This suggests that the velocity gradient associated with the CIR formation can efficiently create a seed population of PUIs before a shock forms even without stochastic acceleration. Thus, local CIR compressions without shocks may play a significant role in the acceleration process as suggested previously.

  15. Pressure-sensitive paint measurement on co-rotating disks in a hard disk drive

    NASA Astrophysics Data System (ADS)

    Kameya, Tomohiro; Matsuda, Yu; Yamaguchi, Hiroki; Egami, Yasuhiro; Niimi, Tomohide

    2012-01-01

    There is much demand for improvement in the performance of a hard disk drive (HDD) along with recent rapid developments of information technology. While high-speed disk rotation of a HDD is necessary to accommodate such needs, it causes disk flutter induced by pressure fluctuation on disks and degrades reliability of a HDD. In order to understand the mechanism of the fluttering phenomenon, it is important to know pressure field on the rotating disk. However, it is impossible to measure the pressure by ordinary methods such as pressure taps. Pressure-sensitive paint (PSP) is a pressure measurement technique based on the oxygen quenching of luminescence and enables us to measure the pressure non-invasively. In general, however, the temperature sensitivity of PSP makes it difficult to measure the precise pressure on the surface with temperature distribution. We measured the time-averaged pressure on the disk rotating at 10 000-20 000 rpm for the first time by adopting a temperature-insensitive PSP composed of pyrene sulfonic acid (PySO 3H) as a luminophore. It was found that the pressure forms a concentric circular distribution and decreases toward the center of the disk. Additionally, we elucidate how disk rotational speed and spacing between co-rotating disks influence on the pressure field.

  16. SOLAR CYCLE ABUNDANCE VARIATIONS IN COROTATING INTERACTION REGIONS: EVIDENCE FOR A SUPRATHERMAL ION SEED POPULATION

    SciTech Connect

    Mason, G. M.; Desai, M. I.; Li, G.

    2012-04-01

    We have surveyed the heavy ion composition of corotating interaction regions (CIRs) over the recent solar minimum and combined this with our earlier survey to cover the 1998-2011 period encompassing a full solar cycle and onset of the new cycle. We find that the solar minimum CIR intensities and spectral forms are similar to those in active periods, indicating that the basic acceleration mechanism does not vary with solar activity for energies below a few MeV nucleon{sup -1}. However, the heavy ion abundances show a clear correlation with sunspot number, where heavy ions are more enhanced during active periods. Over the mass range He-Fe, the enhancement is organized by a power law in Q/M with exponent -1.9, with Fe/O varying by a factor of {approx}6. During solar minimum CIR Fe/O was {approx}0.05, well below the corresponding solar wind ratio. Previous studies have shown that rare ions (He{sup +}, {sup 3}He) enhanced in CIRs come from the suprathermal ion pool. The observations presented here extend this evidence, indicating that in addition to rare He{sup +} and {sup 3}He the CIR major heavy ion species are accelerated out of the suprathermal ion pool, not the bulk solar wind.

  17. Theory comparison and numerical benchmarking on neoclassical toroidal viscosity torque

    SciTech Connect

    Wang, Zhirui; Park, Jong-Kyu; Logan, Nikolas; Kim, Kimin; Menard, Jonathan E.; Liu, Yueqiang

    2014-04-15

    Systematic comparison and numerical benchmarking have been successfully carried out among three different approaches of neoclassical toroidal viscosity (NTV) theory and the corresponding codes: IPEC-PENT is developed based on the combined NTV theory but without geometric simplifications [Park et al., Phys. Rev. Lett. 102, 065002 (2009)]; MARS-Q includes smoothly connected NTV formula [Shaing et al., Nucl. Fusion 50, 025022 (2010)] based on Shaing's analytic formulation in various collisionality regimes; MARS-K, originally computing the drift kinetic energy, is upgraded to compute the NTV torque based on the equivalence between drift kinetic energy and NTV torque [J.-K. Park, Phys. Plasma 18, 110702 (2011)]. The derivation and numerical results both indicate that the imaginary part of drift kinetic energy computed by MARS-K is equivalent to the NTV torque in IPEC-PENT. In the benchmark of precession resonance between MARS-Q and MARS-K/IPEC-PENT, the agreement and correlation between the connected NTV formula and the combined NTV theory in different collisionality regimes are shown for the first time. Additionally, both IPEC-PENT and MARS-K indicate the importance of the bounce harmonic resonance which can greatly enhance the NTV torque when E×B drift frequency reaches the bounce resonance condition.

  18. Theory comparison and numerical benchmarking on neoclassical toroidal viscosity torque

    NASA Astrophysics Data System (ADS)

    Wang, Zhirui; Park, Jong-Kyu; Liu, Yueqiang; Logan, Nikolas; Kim, Kimin; Menard, Jonathan E.

    2014-04-01

    Systematic comparison and numerical benchmarking have been successfully carried out among three different approaches of neoclassical toroidal viscosity (NTV) theory and the corresponding codes: IPEC-PENT is developed based on the combined NTV theory but without geometric simplifications [Park et al., Phys. Rev. Lett. 102, 065002 (2009)]; MARS-Q includes smoothly connected NTV formula [Shaing et al., Nucl. Fusion 50, 025022 (2010)] based on Shaing's analytic formulation in various collisionality regimes; MARS-K, originally computing the drift kinetic energy, is upgraded to compute the NTV torque based on the equivalence between drift kinetic energy and NTV torque [J.-K. Park, Phys. Plasma 18, 110702 (2011)]. The derivation and numerical results both indicate that the imaginary part of drift kinetic energy computed by MARS-K is equivalent to the NTV torque in IPEC-PENT. In the benchmark of precession resonance between MARS-Q and MARS-K/IPEC-PENT, the agreement and correlation between the connected NTV formula and the combined NTV theory in different collisionality regimes are shown for the first time. Additionally, both IPEC-PENT and MARS-K indicate the importance of the bounce harmonic resonance which can greatly enhance the NTV torque when E ×B drift frequency reaches the bounce resonance condition.

  19. Magnetic Tweezers for the Measurement of Twist and Torque

    PubMed Central

    Lipfert, Jan; Lee, Mina; Ordu, Orkide; Kerssemakers, Jacob W. J.; Dekker, Nynke H.

    2014-01-01

    Single-molecule techniques make it possible to investigate the behavior of individual biological molecules in solution in real time. These techniques include so-called force spectroscopy approaches such as atomic force microscopy, optical tweezers, flow stretching, and magnetic tweezers. Amongst these approaches, magnetic tweezers have distinguished themselves by their ability to apply torque while maintaining a constant stretching force. Here, it is illustrated how such a “conventional” magnetic tweezers experimental configuration can, through a straightforward modification of its field configuration to minimize the magnitude of the transverse field, be adapted to measure the degree of twist in a biological molecule. The resulting configuration is termed the freely-orbiting magnetic tweezers. Additionally, it is shown how further modification of the field configuration can yield a transverse field with a magnitude intermediate between that of the “conventional” magnetic tweezers and the freely-orbiting magnetic tweezers, which makes it possible to directly measure the torque stored in a biological molecule. This configuration is termed the magnetic torque tweezers. The accompanying video explains in detail how the conversion of conventional magnetic tweezers into freely-orbiting magnetic tweezers and magnetic torque tweezers can be accomplished, and demonstrates the use of these techniques. These adaptations maintain all the strengths of conventional magnetic tweezers while greatly expanding the versatility of this powerful instrument. PMID:24894412

  20. Ultrasonic resonant piezoelectric actuator with intrinsic torque measurement.

    PubMed

    Pott, Peter P; Matich, Sebastian; Schlaak, Helmut F

    2012-11-01

    Piezoelectric ultrasonic actuators are widely used in small-scale actuation systems, in which a closed-loop position control is usually utilized. To save an additional torque sensor, the intrinsic measurement capabilities of the piezoelectric material can be employed. To prove feasibility, a motor setup with clearly separated actuation for the friction and driving forces is chosen. The motor concept is based on resonant ultrasonic vibrations. To assess the effects of the direct piezoelectric effect, a capacitance bridge-type circuit has been selected. Signal processing is done by a measurement card with an integrated field-programmable gate array. The motor is used to drive a winch, and different torques are applied by means of weights to be lifted. Assessing the bridge voltage, a good proportionality to the applied torque of 1.47 mV/mN·m is shown. A hysteresis of 1% has been determined. The chosen motor concept is useful for intrinsic torque measurement. However, it provides drawbacks in terms of limited mechanical performance, wear, and thermal losses because of the soft piezoelectric material. Future work will comprise the application of the method to commercially available piezoelectric actuators as well as the implementation of the measurement circuit in an embedded system. PMID:23192814

  1. Insertion torque, resonance frequency, and removal torque analysis of microimplants.

    PubMed

    Tseng, Yu-Chuan; Ting, Chun-Chan; Du, Je-Kang; Chen, Chun-Ming; Wu, Ju-Hui; Chen, Hong-Sen

    2016-09-01

    This study aimed to compare the insertion torque (IT), resonance frequency (RF), and removal torque (RT) among three microimplant brands. Thirty microimplants of the three brands were used as follows: Type A (titanium alloy, 1.5-mm × 8-mm), Type B (stainless steel, 1.5-mm × 8-mm), and Type C (titanium alloy, 1.5-mm × 9-mm). A synthetic bone with a 2-mm cortical bone and bone marrow was used. Each microimplant was inserted into the synthetic bone, without predrilling, to a 7 mm depth. The IT, RF, and RT were measured in both vertical and horizontal directions. One-way analysis of variance and Spearman's rank correlation coefficient tests were used for intergroup and intragroup comparisons, respectively. In the vertical test, the ITs of Type C (7.8 Ncm) and Type B (7.5 Ncm) were significantly higher than that of Type A (4.4 Ncm). The RFs of Type C (11.5 kHz) and Type A (10.2 kHz) were significantly higher than that of Type B (7.5 kHz). Type C (7.4 Ncm) and Type B (7.3 Ncm) had significantly higher RTs than did Type A (4.1 Ncm). In the horizontal test, both the ITs and RTs were significantly higher for Type C, compared with Type A. No significant differences were found among the groups, and the study hypothesis was accepted. Type A had the lowest inner/outer diameter ratio and widest apical facing angle, engendering the lowest IT and highest RF values. However, no significant correlations in the IT, RF, and RT were observed among the three groups.

  2. Insertion torque, resonance frequency, and removal torque analysis of microimplants.

    PubMed

    Tseng, Yu-Chuan; Ting, Chun-Chan; Du, Je-Kang; Chen, Chun-Ming; Wu, Ju-Hui; Chen, Hong-Sen

    2016-09-01

    This study aimed to compare the insertion torque (IT), resonance frequency (RF), and removal torque (RT) among three microimplant brands. Thirty microimplants of the three brands were used as follows: Type A (titanium alloy, 1.5-mm × 8-mm), Type B (stainless steel, 1.5-mm × 8-mm), and Type C (titanium alloy, 1.5-mm × 9-mm). A synthetic bone with a 2-mm cortical bone and bone marrow was used. Each microimplant was inserted into the synthetic bone, without predrilling, to a 7 mm depth. The IT, RF, and RT were measured in both vertical and horizontal directions. One-way analysis of variance and Spearman's rank correlation coefficient tests were used for intergroup and intragroup comparisons, respectively. In the vertical test, the ITs of Type C (7.8 Ncm) and Type B (7.5 Ncm) were significantly higher than that of Type A (4.4 Ncm). The RFs of Type C (11.5 kHz) and Type A (10.2 kHz) were significantly higher than that of Type B (7.5 kHz). Type C (7.4 Ncm) and Type B (7.3 Ncm) had significantly higher RTs than did Type A (4.1 Ncm). In the horizontal test, both the ITs and RTs were significantly higher for Type C, compared with Type A. No significant differences were found among the groups, and the study hypothesis was accepted. Type A had the lowest inner/outer diameter ratio and widest apical facing angle, engendering the lowest IT and highest RF values. However, no significant correlations in the IT, RF, and RT were observed among the three groups. PMID:27638407

  3. Particle Acceleration at Corotating Interaction Regions in the Heliosphere

    NASA Astrophysics Data System (ADS)

    Tsubouchi, K.

    2014-11-01

    Hybrid simulations are performed to investigate the dynamics of both solar wind protons and interplanetary pickup ions (PUIs) around the corotating interaction region (CIR). The one-dimensional system is applied in order to focus on processes in the direction of CIR propagation. The CIR is bounded by forward and reverse shocks, which are responsible for particle acceleration. The effective acceleration of solar wind protons takes place when the reverse shock (fast wind side) favors a quasi-parallel regime. The diffusive process accounts for this acceleration, and particles can gain energy in a suprathermal range (on the order of 10 keV). In contrast, the PUI acceleration around the shock differs from the conventional model in which the motional electric field along the shock surface accelerates particles. Owing to their large gyroradius, PUIs can gyrate between the upstream and downstream, several proton inertial lengths away from the shock. This "cross-shock" gyration results in a net velocity increase in the field-aligned component, indicating that the magnetic mirror force is responsible for acceleration. The PUIs that remain in the vicinity of the shock for a long duration (tens of gyroperiods) gain much energy and are reflected back toward the upstream. These reflected energetic PUIs move back and forth along the magnetic field between a pair of CIRs that are magnetically connected. The PUIs are repeatedly accelerated in each reflection, leading to a maximum energy gain close to 100 keV. This mechanism can be evaluated in terms of "preacceleration" for the generation of anomalous cosmic rays.

  4. Interface structure of co-rotating interaction regions

    NASA Technical Reports Server (NTRS)

    Ogilvie, K. W.; Roelof, E. C.; Forsyth, R. J.

    1997-01-01

    Plasma and particle observations on Ulysses during its passes through the southern and northern heliosphere have revealed that, inside the streamer belt, the large-scale structure of the quiet global heliosphere is dominated by corotating interaction regions (CIRs). Therefore, considerable attention is now being given to the internal plasma structure of CIRs, and in particular, to the manifestations of the stream interfaces that should mark their origins as interactions between low speed solar wind (in the low-latitude streamer belt) and high speed solar wind (from the equatorial extensions of the high latitude polar coronal holes). The SWICS and HI-SCALE experiments on Ulysses combine plasma and energetic particle measurements that are of considerable utility for such studies because, between them, they cover the proton energy range from 10 eV to 5 MeV. These measurements are used, together with magnetic field data, to study the remarkable series of CIRs that occurred during the period beginning July 1992 and the end of 1993 as Ulysses rose from the ecliptic to a southern heliographic latitude of 48 deg. The structure of the regions between the forward and reverse shocks were previously analyzed in terms of the proton specific entropy argument log that should exhibit a discontinuous jump at the stream interface. It was claimed that the stream interface, defined with respect to specific entropy, is also associated with a discontinuity in energetic proton intensities. The energetic particle data (greater than 60 keV) and how they were ordered with respect to interfaces and with respect to the magnetic field were examined.

  5. Particle acceleration at corotating interaction regions in the heliosphere

    SciTech Connect

    Tsubouchi, K.

    2014-11-01

    Hybrid simulations are performed to investigate the dynamics of both solar wind protons and interplanetary pickup ions (PUIs) around the corotating interaction region (CIR). The one-dimensional system is applied in order to focus on processes in the direction of CIR propagation. The CIR is bounded by forward and reverse shocks, which are responsible for particle acceleration. The effective acceleration of solar wind protons takes place when the reverse shock (fast wind side) favors a quasi-parallel regime. The diffusive process accounts for this acceleration, and particles can gain energy in a suprathermal range (on the order of 10 keV). In contrast, the PUI acceleration around the shock differs from the conventional model in which the motional electric field along the shock surface accelerates particles. Owing to their large gyroradius, PUIs can gyrate between the upstream and downstream, several proton inertial lengths away from the shock. This 'cross-shock' gyration results in a net velocity increase in the field-aligned component, indicating that the magnetic mirror force is responsible for acceleration. The PUIs that remain in the vicinity of the shock for a long duration (tens of gyroperiods) gain much energy and are reflected back toward the upstream. These reflected energetic PUIs move back and forth along the magnetic field between a pair of CIRs that are magnetically connected. The PUIs are repeatedly accelerated in each reflection, leading to a maximum energy gain close to 100 keV. This mechanism can be evaluated in terms of 'preacceleration' for the generation of anomalous cosmic rays.

  6. 40 CFR 1065.310 - Torque calibration.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... lever-arm length. Quantify the lever-arm length, NIST-traceable within ±0.5% uncertainty. The lever arm... torque, NIST-traceable within ±1% uncertainty, and account for it as part of the reference torque. (c...% uncertainty. (1) Dead-weight calibration. This technique applies a known force by hanging known weights at...

  7. Radiation Forces and Torques without Stress (Tensors)

    ERIC Educational Resources Information Center

    Bohren, Craig F.

    2011-01-01

    To understand radiation forces and torques or to calculate them does not require invoking photon or electromagnetic field momentum transfer or stress tensors. According to continuum electromagnetic theory, forces and torques exerted by radiation are a consequence of electric and magnetic fields acting on charges and currents that the fields induce…

  8. Forces and torques between nonintersecting straight currents

    NASA Astrophysics Data System (ADS)

    Binder, P.-M.; Cross, Felicity; Silva, J. K.

    2016-07-01

    We analyse two very long current-carrying straight wires that point in arbitrary directions without touching. We find general expressions for the forces and torques for arbitrary points on one wire due to the other. This allows us to make calculations for the overall forces and torques and statements about the stability of parallel and anti-parallel current arrangements.

  9. In-line rotating capacitive torque sensor

    DOEpatents

    Kronberg, James W.

    1991-01-01

    A method and apparatus for measuring torques developed along a rotating mechanical assembly comprising a rotating inner portion and a stationary outer portion. The rotating portion has an electrically-conductive flexing section fitted between two coaxial shafts in a configuration which varies radially in accordance with applied torque. The stationary portion comprises a plurality of conductive plates forming a surface concentric with and having a diameter slightly larger than the diameter of the rotating portion. The capacitance between the outer, nonrotating and inner, rotating portion varies with changes in the radial configuration of the rotating portion. Signal output varies approximately linearly with torque for small torques, nonlinearly for larger torques. The sensor is preferably surrounded by a conductive shell to minimize electrical interference from external sources.

  10. Spin-transfer torques in helimagnets

    NASA Astrophysics Data System (ADS)

    Hals, Kjetil M. D.; Brataas, Arne

    2013-05-01

    We theoretically investigate current-induced magnetization dynamics in chiral-lattice helimagnets. Spin-orbit coupling in noncentrosymmetric crystals induces a reactive spin-transfer torque that has not been previously considered. We demonstrate how the torque is governed by the crystal symmetry and acts as an effective magnetic field along the current direction in cubic B20-type crystals. The effects of the new torque are computed for current-induced dynamics of spin spirals and the Doppler shift of spin waves. In current-induced spin-spiral motion, the new torque tilts the spiral structure. The spin waves of the spiral structure are initially displaced by the new torque, while the dispersion relation is unaffected.

  11. An information preserving method for producing full coverage CoRoT light curves

    NASA Astrophysics Data System (ADS)

    Pascual-Granado, J.; Garrido, R.; Suárez, J. C.

    2015-09-01

    Invalid flux measurements, caused mainly by the South Atlantic Anomaly crossing of the CoRoT satellite, introduce aliases in the periodogram and wrong amplitudes. It has been demonstrated that replacing such invalid data with a linear interpolation is not harmless. On the other side, using power spectrum estimators for unevenly sampled time series is not only less computationally efficient but it leads to difficulties in the interpretation of the results. Therefore, even when the gaps are rather small and the duty cycle is high enough the use of gap-filling methods is a gain in frequency analysis. However, the method must preserve the information contained in the time series. In this work we give a short description of an information preserving method (MIARMA) and show some results when applying it to CoRoT seismo light curves. The method is implemented as the second step of a pipeline for CoRoT data analysis.

  12. Skid Prevention Control for IPMSM Driven EVs Based on Improved Torque Reduction Characteristics

    NASA Astrophysics Data System (ADS)

    Satake, Masamitsu; Kawashima, Kiyotaka; Uchida, Toshiyuki; Hori, Yoichi

    In this paper, skid prevention control based on torque reduction is proposed for EVs driven by an IPMSM. The traction characteristics of the electric vehicle are improved by using a modified current controller to rapidly reduce the torque of the driving motor. In order to compensate for back-EMF, a disturbance observer is introduced. In addition, we propose skid prevention for an IPMSM by torque reduction using both the dq-axes currents. Further, we verify the effect of each control method by conducting experiments in which the electric vehicle is driven on a slippery road.

  13. The study of Be stars with the CoRoT satellite

    NASA Astrophysics Data System (ADS)

    Diago, P. D.; Gutierrez-Soto, J.; Fabregat, J.; Suso, J.; COROT Be Team

    2011-11-01

    The CoRoT space mission, launched in December 2006, is a spacecraft devoted to the study of the stellar interiors and the exo-planet search. Concerning the seismology of the Be stars, the presence of pulsations in late-type Be stars is still a matter of controversy. It constitutes an important issue to establish the relationship between non-radial pulsations and the mass-loss mechanism in Be stars. In this field, the CoRoT satellite is providing data with an unprecedent quality and precision that is confirming non-radial pulsations in Be stars. The CoRoT Be Team is an international collaboration composed by members from France, Spain, Brazil and Belgium and is in charge of the exploitation and analysis of the Be stars data. In this work we present the highlighted results of the observed Be stars by CoRoT and the future prospects of the CoRoT Be Team. These results include the detection of the Be star HD 49 330 during an outburst phase and the measurement of the change in the oscillation spectrum during this rare event. These observations gave insight into the nature of the explosion. It will help to solve a question that has been pending for years: are oscillations the cause of the outbursts? Moreover, for the first time, the CoRoT satellite has detected simultaneously the rotational and the pulsational frequencies for the Be star HD 50 209, which constitutes a proof of the presence of pulsations in the Be stars. %J Highlights of Spanish Astrophysics VI, Proceedings of the IX Scientific Meeting of the Spanish Astronomical Society (SEA), held in Madrid, September 13 - 17, 2010, Eds.: M. R. Zapatero Osorio, J. Gorgas, J. Maiz Apellaniz, J. R. Pardo, and A. Gil de Paz., p. 531-531

  14. Rate and nature of false positives in the CoRoT exoplanet search

    NASA Astrophysics Data System (ADS)

    Almenara, J. M.; Deeg, H. J.; Aigrain, S.; Alonso, R.; Auvergne, M.; Baglin, A.; Barbieri, M.; Barge, P.; Bordé, P.; Bouchy, F.; Bruntt, H.; Cabrera, J.; Carone, L.; Carpano, S.; Catala, C.; Csizmadia, Sz.; de La Reza, R.; Deleuil, M.; Dvorak, R.; Erikson, A.; Fridlund, M.; Gandolfi, D.; Gillon, M.; Gondoin, P.; Guenther, E.; Guillot, T.; Hatzes, A.; Hébrard, G.; Jorda, L.; Lammer, H.; Léger, A.; Llebaria, A.; Loeillet, B.; Magain, P.; Mayor, M.; Mazeh, T.; Moutou, C.; Ollivier, M.; Pätzold, M.; Pont, F.; Queloz, D.; Rauer, H.; Régulo, C.; Renner, S.; Rouan, D.; Samuel, B.; Schneider, J.; Shporer, A.; Wuchterl, G.; Zucker, S.

    2009-10-01

    Context: The CoRoT satellite searches for planets by applying the transit method, monitoring up to 12 000 stars in the galactic plane for 150 days in each observing run. This search is contaminated by a large fraction of false positives, caused by different eclipsing binary configurations that might be confused with a transiting planet. Aims: We evaluate the rates and nature of false positives in the CoRoT exoplanets search and compare our results with semiempirical predictions. Methods: We consider the detected binary and planet candidates in the first three extended CoRoT runs, and classify the results of the follow-up observations completed to verify their planetary nature. We group the follow-up results into undiluted binaries, diluted binaries, and planets and compare their abundances with predictions from the literature. Results: 83% of the initial detections are classified as false positives using only the CoRoT light-curves, the remaining 17% require follow-up observations. Finally, 12% of the candidates in the follow-up program are planets. The shape of the overall distribution of the false positive rate follows previous predictions, except for candidates with transit depths below about 0.4%. For candidates with transit depths in the range from 0.1-0.4%, CoRoT detections are nearly complete, and this difference from predictions is probably real and dominated by a lower than expected abundance of diluted eclipsing binaries. The CoRoT space mission, launched on December 27th 2006, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil , ESA (RSSD and Science Programme), Germany and Spain.

  15. Transiting exoplanets from the CoRoT space mission. XXVII. CoRoT-28b, a planet orbiting an evolved star, and CoRoT-29b, a planet showing an asymmetric transit

    NASA Astrophysics Data System (ADS)

    Cabrera, J.; Csizmadia, Sz.; Montagnier, G.; Fridlund, M.; Ammler-von Eiff, M.; Chaintreuil, S.; Damiani, C.; Deleuil, M.; Ferraz-Mello, S.; Ferrigno, A.; Gandolfi, D.; Guillot, T.; Guenther, E. W.; Hatzes, A.; Hébrard, G.; Klagyivik, P.; Parviainen, H.; Pasternacki, Th.; Pätzold, M.; Sebastian, D.; Tadeu dos Santos, M.; Wuchterl, G.; Aigrain, S.; Alonso, R.; Almenara, J.-M.; Armstrong, J. D.; Auvergne, M.; Baglin, A.; Barge, P.; Barros, S. C. C.; Bonomo, A. S.; Bordé, P.; Bouchy, F.; Carpano, S.; Chaffey, C.; Deeg, H. J.; Díaz, R. F.; Dvorak, R.; Erikson, A.; Grziwa, S.; Korth, J.; Lammer, H.; Lindsay, C.; Mazeh, T.; Moutou, C.; Ofir, A.; Ollivier, M.; Pallé, E.; Rauer, H.; Rouan, D.; Samuel, B.; Santerne, A.; Schneider, J.

    2015-07-01

    Context. We present the discovery of two transiting extrasolar planets by the satellite CoRoT. Aims: We aim at a characterization of the planetary bulk parameters, which allow us to further investigate the formation and evolution of the planetary systems and the main properties of the host stars. Methods: We used the transit light curve to characterize the planetary parameters relative to the stellar parameters. The analysis of HARPS spectra established the planetary nature of the detections, providing their masses. Further photometric and spectroscopic ground-based observations provided stellar parameters (log g, Teff, v sin i) to characterize the host stars. Our model takes the geometry of the transit to constrain the stellar density into account, which when linked to stellar evolutionary models, determines the bulk parameters of the star. Because of the asymmetric shape of the light curve of one of the planets, we had to include the possibility in our model that the stellar surface was not strictly spherical. Results: We present the planetary parameters of CoRoT-28b, a Jupiter-sized planet (mass 0.484 ± 0.087 MJup; radius 0.955 ± 0.066 RJup) orbiting an evolved star with an orbital period of 5.208 51 ± 0.000 38 days, and CoRoT-29b, another Jupiter-sized planet (mass 0.85 ± 0.20 MJup; radius 0.90 ± 0.16 RJup) orbiting an oblate star with an orbital period of 2.850 570 ± 0.000 006 days. The reason behind the asymmetry of the transit shape is not understood at this point. Conclusions: These two new planetary systems have very interesting properties and deserve further study, particularly in the case of the star CoRoT-29. The CoRoT space mission, launched on December 27th 2006, was developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany, and Spain. Based on observations obtained with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland

  16. Consistent linearization of the element-independent corotational formulation for the structural analysis of general shells

    NASA Technical Reports Server (NTRS)

    Rankin, C. C.

    1988-01-01

    A consistent linearization is provided for the element-dependent corotational formulation, providing the proper first and second variation of the strain energy. As a result, the warping problem that has plagued flat elements has been overcome, with beneficial effects carried over to linear solutions. True Newton quadratic convergence has been restored to the Structural Analysis of General Shells (STAGS) code for conservative loading using the full corotational implementation. Some implications for general finite element analysis are discussed, including what effect the automatic frame invariance provided by this work might have on the development of new, improved elements.

  17. How to separate the low amplitude delta Scuti variation in CoRoT data unambigousely?

    NASA Astrophysics Data System (ADS)

    Benko, Jozsef M.; Paparo, Margit

    2015-08-01

    Rich regular frequency patterns were found in the Fourier spectra of low-amplitude Delta Scuti stars observed by CoRoT satellite. The CoRoT observations are, however, influenced by the disturbing effect of the SAA. The effect is marginal for high amplitude variable stars but it could be dangerous in the case of low amplitude variables, especially if the frequency range of the intrinsic variation overlaps the instrumental frequencies. Systematic tests were carried out both on synthetic and real data. Our aim was to determine a limit amplitude above which we were sure that the frequency pattern belonged to the stars.

  18. Transiting exoplanets from the CoRoT space mission. VIII. CoRoT-7b: the first super-Earth with measured radius

    NASA Astrophysics Data System (ADS)

    Léger, A.; Rouan, D.; Schneider, J.; Barge, P.; Fridlund, M.; Samuel, B.; Ollivier, M.; Guenther, E.; Deleuil, M.; Deeg, H. J.; Auvergne, M.; Alonso, R.; Aigrain, S.; Alapini, A.; Almenara, J. M.; Baglin, A.; Barbieri, M.; Bruntt, H.; Bordé, P.; Bouchy, F.; Cabrera, J.; Catala, C.; Carone, L.; Carpano, S.; Csizmadia, Sz.; Dvorak, R.; Erikson, A.; Ferraz-Mello, S.; Foing, B.; Fressin, F.; Gandolfi, D.; Gillon, M.; Gondoin, Ph.; Grasset, O.; Guillot, T.; Hatzes, A.; Hébrard, G.; Jorda, L.; Lammer, H.; Llebaria, A.; Loeillet, B.; Mayor, M.; Mazeh, T.; Moutou, C.; Pätzold, M.; Pont, F.; Queloz, D.; Rauer, H.; Renner, S.; Samadi, R.; Shporer, A.; Sotin, Ch.; Tingley, B.; Wuchterl, G.; Adda, M.; Agogu, P.; Appourchaux, T.; Ballans, H.; Baron, P.; Beaufort, T.; Bellenger, R.; Berlin, R.; Bernardi, P.; Blouin, D.; Baudin, F.; Bodin, P.; Boisnard, L.; Boit, L.; Bonneau, F.; Borzeix, S.; Briet, R.; Buey, J.-T.; Butler, B.; Cailleau, D.; Cautain, R.; Chabaud, P.-Y.; Chaintreuil, S.; Chiavassa, F.; Costes, V.; Cuna Parrho, V.; de Oliveira Fialho, F.; Decaudin, M.; Defise, J.-M.; Djalal, S.; Epstein, G.; Exil, G.-E.; Fauré, C.; Fenouillet, T.; Gaboriaud, A.; Gallic, A.; Gamet, P.; Gavalda, P.; Grolleau, E.; Gruneisen, R.; Gueguen, L.; Guis, V.; Guivarc'h, V.; Guterman, P.; Hallouard, D.; Hasiba, J.; Heuripeau, F.; Huntzinger, G.; Hustaix, H.; Imad, C.; Imbert, C.; Johlander, B.; Jouret, M.; Journoud, P.; Karioty, F.; Kerjean, L.; Lafaille, V.; Lafond, L.; Lam-Trong, T.; Landiech, P.; Lapeyrere, V.; Larqué, T.; Laudet, P.; Lautier, N.; Lecann, H.; Lefevre, L.; Leruyet, B.; Levacher, P.; Magnan, A.; Mazy, E.; Mertens, F.; Mesnager, J.-M.; Meunier, J.-C.; Michel, J.-P.; Monjoin, W.; Naudet, D.; Nguyen-Kim, K.; Orcesi, J.-L.; Ottacher, H.; Perez, R.; Peter, G.; Plasson, P.; Plesseria, J.-Y.; Pontet, B.; Pradines, A.; Quentin, C.; Reynaud, J.-L.; Rolland, G.; Rollenhagen, F.; Romagnan, R.; Russ, N.; Schmidt, R.; Schwartz, N.; Sebbag, I.; Sedes, G.; Smit, H.; Steller, M. B.; Sunter, W.; Surace, C.; Tello, M.; Tiphène, D.; Toulouse, P.; Ulmer, B.; Vandermarcq, O.; Vergnault, E.; Vuillemin, A.; Zanatta, P.

    2009-10-01

    Aims: We report the discovery of very shallow (Δ F/F ≈ 3.4× 10-4), periodic dips in the light curve of an active V = 11.7 G9V star observed by the CoRoT satellite, which we interpret as caused by a transiting companion. We describe the 3-colour CoRoT data and complementary ground-based observations that support the planetary nature of the companion. Methods: We used CoRoT colours information, good angular resolution ground-based photometric observations in- and out- of transit, adaptive optics imaging, near-infrared spectroscopy, and preliminary results from radial velocity measurements, to test the diluted eclipsing binary scenarios. The parameters of the host star were derived from optical spectra, which were then combined with the CoRoT light curve to derive parameters of the companion. Results: We examined all conceivable cases of false positives carefully, and all the tests support the planetary hypothesis. Blends with separation >0.40´´or triple systems are almost excluded with a 8 × 10-4 risk left. We conclude that, inasmuch we have been exhaustive, we have discovered a planetary companion, named CoRoT-7b, for which we derive a period of 0.853 59 ± 3 × 10-5 day and a radius of Rp = 1.68 ± 0.09 R_Earth. Analysis of preliminary radial velocity data yields an upper limit of 21 M_Earth for the companion mass, supporting the finding. Conclusions: CoRoT-7b is very likely the first Super-Earth with a measured radius. This object illustrates what will probably become a common situation with missions such as Kepler, namely the need to establish the planetary origin of transits in the absence of a firm radial velocity detection and mass measurement. The composition of CoRoT-7b remains loosely constrained without a precise mass. A very high surface temperature on its irradiated face, ≈1800-2600 K at the substellar point, and a very low one, ≈50 K, on its dark face assuming no atmosphere, have been derived. The CoRoT space mission, launched on 27

  19. Optimal design and selection of magneto-rheological brake types based on braking torque and mass

    NASA Astrophysics Data System (ADS)

    Nguyen, Q. H.; Lang, V. T.; Choi, S. B.

    2015-06-01

    In developing magnetorheological brakes (MRBs), it is well known that the braking torque and the mass of the MRBs are important factors that should be considered in the product’s design. This research focuses on the optimal design of different types of MRBs, from which we identify an optimal selection of MRB types, considering braking torque and mass. In the optimization, common types of MRBs such as disc-type, drum-type, hybrid-type, and T-shape types are considered. The optimization problem is to find an optimal MRB structure that can produce the required braking torque while minimizing its mass. After a brief description of the configuration of the MRBs, the MRBs’ braking torque is derived based on the Herschel-Bulkley rheological model of the magnetorheological fluid. Then, the optimal designs of the MRBs are analyzed. The optimization objective is to minimize the mass of the brake while the braking torque is constrained to be greater than a required value. In addition, the power consumption of the MRBs is also considered as a reference parameter in the optimization. A finite element analysis integrated with an optimization tool is used to obtain optimal solutions for the MRBs. Optimal solutions of MRBs with different required braking torque values are obtained based on the proposed optimization procedure. From the results, we discuss the optimal selection of MRB types, considering braking torque and mass.

  20. Torque Measurement of 3-DOF Haptic Master Operated by Controllable Electrorheological Fluid

    NASA Astrophysics Data System (ADS)

    Oh, Jong-Seok; Choi, Seung-Bok; Lee, Yang-Sub

    2015-02-01

    This work presents a torque measurement method of 3-degree-of-freedom (3-DOF) haptic master featuring controllable electrorheological (ER) fluid. In order to reflect the sense of an organ for a surgeon, the ER haptic master which can generate the repulsive torque of an organ is utilized as a remote controller for a surgery robot. Since accurate representation of organ feeling is essential for the success of the robot-assisted surgery, it is indispensable to develop a proper torque measurement method of 3-DOF ER haptic master. After describing the structural configuration of the haptic master, the torque models of ER spherical joint are mathematically derived based on the Bingham model of ER fluid. A new type of haptic device which has pitching, rolling, and yawing motions is then designed and manufactured using a spherical joint mechanism. Subsequently, the field-dependent parameters of the Bingham model are identified and generating repulsive torque according to applied electric field is measured. In addition, in order to verify the effectiveness of the proposed torque model, a comparative work between simulated and measured torques is undertaken.

  1. Geoeffectiveness of Magnetic Storms Driven by Corotating Interaction Regions (CIRs) and Ejecta-Related Events

    NASA Astrophysics Data System (ADS)

    Turner, N. E.; Mitchell, E. J.; Knipp, D. J.

    2005-12-01

    We investigate the energetics of magnetic storms associated with corotating interaction regions (CIRs). We analyze storms driven by CIRs and compare to those driven by ejecta-related events to determine how they differ in overall properties and in particular in their distribution of energy. To compare these different types of events, we look at events with comparable input parameters such as the epsilon parameter and note the properties of the resulting storms. We estimate the energy output by looking at the ring current and ionospheric Joule heating and auroral precipitation derived from Dst* and the PC index. In general, ejecta-driven storms seem to produce more intense events, as parameterized by Dst*, but they are not as long-lasting, and in many cases do not deposit the same amount of energy. This is observed even for events which are estimated to have similar total input quantities, such as epsilon. This may be related to the high speed of the solar wind, in that an increased magnetosonic Mach number may influence the reconnection rate and therefore the coupling. Additionally, we find that the energy output in the recovery phase of CIR-driven storms correlates highly with energy input during recovery, suggesting that the system is still being driven by the solar wind in recovery. This is different from what we find with ejecta-driven storms, which depend more on input energy from the main phase. Additionally, we find the efficiency of the coupling to vary greatly from CIR to ejecta-driven storms, with the CIR storms coupling substantially more efficiently.

  2. Transiting exoplanets from the CoRoT space mission. XXIII. CoRoT-21b: a doomed large Jupiter around a faint subgiant star

    NASA Astrophysics Data System (ADS)

    Pätzold, M.; Endl, M.; Csizmadia, Sz.; Gandolfi, D.; Jorda, L.; Grziwa, S.; Carone, L.; Pasternacki, T.; Aigrain, S.; Almenara, J. M.; Alonso, R.; Auvergne, M.; Baglin, A.; Barge, P.; Bonomo, A. S.; Bordé, P.; Bouchy, F.; Cabrera, J.; Cavarroc, C.; Cochran, W. B.; Deleuil, M.; Deeg, H. J.; Díaz, R.; Dvorak, R.; Erikson, A.; Ferraz-Mello, S.; Fridlund, M.; Gillon, M.; Guillot, T.; Hatzes, A.; Hébrard, G.; Léger, A.; Llebaria, A.; Lammer, H.; MacQueen, P. J.; Mazeh, T.; Moutou, C.; Ofir, A.; Ollivier, M.; Parviainen, H.; Queloz, D.; Rauer, H.; Rouan, D.; Santerne, A.; Schneider, J.; Tingley, B.; Weingrill, J.; Wuchterl, G.

    2012-09-01

    CoRoT-21, a F8IV star of magnitude V = 16 mag, was observed by the space telescope CoRoT during the Long Run 01 (LRa01) in the first winter field (constellation Monoceros) from October 2007 to March 2008. Transits were discovered during the light curve processing. Radial velocity follow-up observations, however, were performed mainly by the 10-m Keck telescope in January 2010. The companion CoRoT-21b is a Jupiter-like planet of 2.26 ± 0.33 Jupiter masses and 1.30 ± 0.14 Jupiter radii in an circular orbit of semi-major axis 0.0417 ± 0.0011 AU and an orbital period of 2.72474 ± 0.00014 days. The planetary bulk density is (1.36 ± 0.48) × 103 kg m-3, very similar to the bulk density of Jupiter, and follows an M1/3 - R relation like Jupiter. The F8IV star is a sub-giant star of 1.29 ± 0.09 solar masses and 1.95 ± 0.2 solar radii. The star and the planet exchange extremetidal forces that will lead to orbital decay and extreme spin-up of the stellar rotation within 800 Myr if the stellar dissipation is Q∗/k2∗ ≤ 107. The CoRoT space mission, launched on December 27th 2006, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany and Spain.

  3. Transiting exoplanets from the CoRoT space mission. XX. CoRoT-20b: A very high density, high eccentricity transiting giant planet

    NASA Astrophysics Data System (ADS)

    Deleuil, M.; Bonomo, A. S.; Ferraz-Mello, S.; Erikson, A.; Bouchy, F.; Havel, M.; Aigrain, S.; Almenara, J.-M.; Alonso, R.; Auvergne, M.; Baglin, A.; Barge, P.; Bordé, P.; Bruntt, H.; Cabrera, J.; Carpano, S.; Cavarroc, C.; Csizmadia, Sz.; Damiani, C.; Deeg, H. J.; Dvorak, R.; Fridlund, M.; Hébrard, G.; Gandolfi, D.; Gillon, M.; Guenther, E.; Guillot, T.; Hatzes, A.; Jorda, L.; Léger, A.; Lammer, H.; Mazeh, T.; Moutou, C.; Ollivier, M.; Ofir, A.; Parviainen, H.; Queloz, D.; Rauer, H.; Rodríguez, A.; Rouan, D.; Santerne, A.; Schneider, J.; Tal-Or, L.; Tingley, B.; Weingrill, J.; Wuchterl, G.

    2012-02-01

    We report the discovery by the CoRoT space mission of a new giant planet, CoRoT-20b. The planet has a mass of 4.24 ± 0.23 MJup and a radius of 0.84 ± 0.04 RJup. With a mean density of 8.87 ± 1.10 g cm-3, it is among the most compact planets known so far. Evolutionary models for the planet suggest a mass of heavy elements of the order of 800 M⊕ if embedded in a central core, requiring a revision either of the planet formation models or both planet evolution and structure models. We note however that smaller amounts of heavy elements are expected by more realistic models in which they are mixed throughout the envelope. The planet orbits a G-type star with an orbital period of 9.24 days and an eccentricity of 0.56.The star's projected rotational velocity is vsini = 4.5 ± 1.0 km s-1, corresponding to a spin period of 11.5 ± 3.1 days if its axis of rotation is perpendicular to the orbital plane. In the framework of Darwinian theories and neglecting stellar magnetic breaking, we calculate the tidal evolution of the system and show that CoRoT-20b is presently one of the very few Darwin-stable planets that is evolving toward a triple synchronous state with equality of the orbital, planetary and stellar spin periods. The CoRoT space mission, launched on December 27th 2006, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany, and Spain.

  4. Electromagnetic Torque in Tokamaks with Toroidal Asymmetries

    NASA Astrophysics Data System (ADS)

    Logan, Nikolas Christopher

    Toroidal rotation and rotation shear strongly influences stability and confinement in tokamaks. Breaking of the toroidal symmetry by fields orders of magnitude smaller than the axisymmetric field can, however, produce electromagnetic torques that significantly affect the plasma rotation, stability and confinement. These electromagnetic torques are the study of this thesis. There are two typical types of electromagnetic torques in tokamaks: 1) "resonant torques" for which a plasma current defined by a single toroidal and single poloidal harmonic interact with external currents and 2) "nonresonant torques" for which the global plasma response to nonaxisymmetric fields is phase shifted by kinetic effects that drive the rotation towards a neoclassical offset. This work describes the diagnostics and analysis necessary to evaluate the torque by measuring the rate of momentum transfer per unit area in the vacuum region between the plasma and external currents using localized magnetic sensors to measure the Maxwell stress. These measurements provide model independent quantification of both the resonant and nonresonant electromagnetic torques, enabling direct verification of theoretical models. Measured values of the nonresonant torque are shown to agree well with the perturbed equilibrium nonambipolar transport (PENT) code calculation of torque from cross field transport in nonaxisymmetric equilibria. A combined neoclassical toroidal viscosity (NTV) theory, valid across a wide range of kinetic regimes, is fully implemented for the first time in general aspect ratio and shaped plasmas. The code captures pitch angle resonances, reproducing previously inaccessible collisionality limits in the model. The complete treatment of the model enables benchmarking to the hybrid kinetic MHD stability codes MARS-K and MISK, confirming the energy-torque equivalency principle in perturbed equilibria. Experimental validations of PENT results confirm the torque applied by nonaxisymmetric

  5. Radiative torques: analytical model and basic properties

    NASA Astrophysics Data System (ADS)

    Lazarian, A.; Hoang, Thiem

    2007-07-01

    We attempt to get a physical insight into grain alignment processes by studying basic properties of radiative torques (RATs). For this purpose we consider a simple toy model of a helical grain that reproduces well the basic features of RATs. The model grain consists of a spheroidal body with a mirror attached at an angle to it. Being very simple, the model allows analytical description of RATs that act upon it. We show a good correspondence of RATs obtained for this model and those of irregular grains calculated by DDSCAT. Our analysis of the role of different torque components for grain alignment reveals that one of the three RAT components does not affect the alignment, but induces only for grain precession. The other two components provide a generic alignment with grain long axes perpendicular to the radiation direction, if the radiation dominates the grain precession, and perpendicular to magnetic field, otherwise. The latter coincides with the famous predictions of the Davis-Greenstein process, but our model does not invoke paramagnetic relaxation. In fact, we identify a narrow range of angles between the radiation beam and the magnetic field, for which the alignment is opposite to the Davis-Greenstein predictions. This range is likely to vanish, however, in the presence of thermal wobbling of grains. In addition, we find that a substantial part of grains subjected to RATs gets aligned with low angular momentum, which testifies that most of the grains in diffuse interstellar medium do not rotate fast, that is, rotate with thermal or even subthermal velocities. This tendency of RATs to decrease grain angular velocity as a result of the RAT alignment decreases the degree of polarization, by decreasing the degree of internal alignment, that is, the alignment of angular momentum with the grain axes. For the radiation-dominated environments, we find that the alignment can take place on the time-scale much shorter than the time of gaseous damping of grain rotation

  6. Influence of magnetic reluctances of magnetic elements on servo valve torque motors

    NASA Astrophysics Data System (ADS)

    Liu, Changhai; Jiang, Hongzhou

    2016-01-01

    The current research of electro-hydraulic servo valves mainly focuses on the vibration, pressure oscillating and source of noise. Unfortunately, literatures relating to the study of the influence of the magnetic reluctances of the magnetic elements are rarely available. This paper aims to analyze the influence of the magnetic reluctances of the magnetic elements on torque motor. Considering these magnetic reluctances ignored in previous literatures, a new mathematical model of servo valve torque motor is developed and proposed based on the fundamental laws of electromagnetism. By using this new mathematical model and the previous models, electromagnetic torque constant and magnetic spring stiffness are evaluated for a given set of torque motor parameters. A computer simulation by using AMESim software is also performed for the same set of torque motor parameters to verify the proposed model. The theoretical results of electromagnetic torque constant and magnetic spring stiffness evaluated by the proposed model render closer agreement with the simulation results than those evaluated by the previous models. In addition, an experimental measurement of the magnetic flux densities in the air-gaps is carried out by using SFL218 servo valve torque motor. Compared with the theoretical results of the magnetic flux densities in the air-gaps evaluated by the previous models, the theoretical results evaluated by the proposed model also show better agreement with the experimental data. The proposed model shows the influence of the magnetic reluctances of the magnetic elements on the servo valve torque motor, and offers modified and analytical expressions to electromagnetic torque constant and magnetic spring stiffness. These modified and analytical expressions could provide guidance more accurately for a linear control design approach and sensitivity analysis on electro-hydraulic servo valves than the previous expressions.

  7. Torque equilibrium attitude control for Skylab reentry

    NASA Technical Reports Server (NTRS)

    Glaese, J. R.; Kennel, H. F.

    1979-01-01

    All the available torque equilibrium attitudes (most were useless from the standpoint of lack of electrical power) and the equilibrium seeking method are presented, as well as the actual successful application during the 3 weeks prior to Skylab reentry.

  8. Long-Term Tracking of Corotating Density Structures Using Heliospheric Imaging

    NASA Astrophysics Data System (ADS)

    Plotnikov, I.; Rouillard, A. P.; Davies, J. A.; Bothmer, V.; Eastwood, J. P.; Gallagher, P.; Harrison, R. A.; Kilpua, E.; Möstl, C.; Perry, C. H.; Rodriguez, L.; Lavraud, B.; Génot, V.; Pinto, R. F.; Sanchez-Diaz, E.

    2016-08-01

    The systematic monitoring of the solar wind in high-cadence and high-resolution heliospheric images taken by the Solar-Terrestrial Relation Observatory (STEREO) spacecraft permits the study of the spatial and temporal evolution of variable solar wind flows from the Sun out to 1 AU, and beyond. As part of the EU Framework 7 (FP7) Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) project, we have generated a catalog listing the properties of 190 corotating structures well-observed in images taken by the Heliospheric Imager (HI) instruments onboard STEREO-A (ST-A). Based on this catalog, we present here one of very few long-term analyses of solar wind structures advected by the background solar wind. We concentrate on the subset of plasma density structures clearly identified inside corotating structures. This analysis confirms that most of the corotating density structures detected by the heliospheric imagers comprises a series of density inhomogeneities advected by the slow solar wind that eventually become entrained by stream interaction regions. We have derived the spatial-temporal evolution of each of these corotating density structures by using a well-established fitting technique. The mean radial propagation speed of the corotating structures is found to be 311 ±31 km s^{-1}. Such a low mean value corresponds to the terminal speed of the slow solar wind rather than the speed of stream interfaces, which is typically intermediate between the slow and fast solar wind speeds ({˜} 400 km s^{-1}). Using our fitting technique, we predicted the arrival time of each corotating density structure at different probes in the inner heliosphere. We find that our derived speeds are systematically lower by {˜} 100 km s^{-1} than those measured in situ at the predicted impact times. Moreover, for cases when a stream interaction region is clearly detected in situ at the estimated impact time, we find that our derived speeds are lower than the speed of the

  9. Large amplitude oscillation of magnetization in spin-torque oscillator stabilized by field-like torque

    SciTech Connect

    Taniguchi, Tomohiro Kubota, Hitoshi; Imamura, Hiroshi; Tsunegi, Sumito

    2015-05-07

    Oscillation frequency of spin torque oscillator with a perpendicularly magnetized free layer and an in-plane magnetized pinned layer is theoretically investigated by taking into account the field-like torque. It is shown that the field-like torque plays an important role in finding the balance between the energy supplied by the spin torque and the dissipation due to the damping, which results in a steady precession. The validity of the developed theory is confirmed by performing numerical simulations based on the Landau-Lifshitz-Gilbert equation.

  10. Fourth-order acoustic torque in intense sound fields

    NASA Technical Reports Server (NTRS)

    Wang, T. G.; Kanber, H.; Olli, E. E.

    1978-01-01

    The observation of a fourth-order acoustic torque in intense sound fields is reported. The torque was determined by measuring the acoustically induced angular deflection of a polished cylinder suspended by a torsion fiber. This torque was measured in a sound field of amplitude greater than that in which first-order acoustic torque has been observed.

  11. Interfacial spin-orbit torque without bulk spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Emori, Satoru; Nan, Tianxiang; Belkessam, Amine M.; Wang, Xinjun; Matyushov, Alexei D.; Babroski, Christopher J.; Gao, Yuan; Lin, Hwaider; Sun, Nian X.

    2016-05-01

    An electric current in the presence of spin-orbit coupling can generate a spin accumulation that exerts torques on a nearby magnetization. We demonstrate that, even in the absence of materials with strong bulk spin-orbit coupling, a torque can arise solely due to interfacial spin-orbit coupling, namely, Rashba-Eldestein effects at metal/insulator interfaces. In magnetically soft NiFe sandwiched between a weak spin-orbit metal (Ti) and insulator (Al2O3 ), this torque appears as an effective field, which is significantly larger than the Oersted field and qualitatively modified by inserting an additional layer between NiFe and Al2O3 . Our findings point to unconventional routes for tuning spin-orbit torques by engineering interfacial electric dipoles.

  12. Oscillation characteristics of zero-field spin transfer oscillators with field-like torque

    SciTech Connect

    Guo, Yuan-Yuan; Xue, Hai-Bin; Liu, Zhe-Jie

    2015-05-15

    We theoretically investigate the influence of the field-like spin torque term on the oscillation characteristics of spin transfer oscillators, which are based on MgO magnetic tunnel junctions (MTJs) consisting of a perpendicular magnetized free layer and an in-plane magnetized pinned layer. It is demonstrated that the field-like torque has a strong impact on the steady-state precession current region and the oscillation frequency. In particular, the steady-state precession can occur at zero applied magnetic field when the ratio between the field-like torque and the spin transfer torque takes up a negative value. In addition, the dependence of the oscillation properties on the junction sizes has also been analyzed. The results indicate that this compact structure of spin transfer oscillator without the applied magnetic field is practicable under certain conditions, and it may be a promising configuration for the new generation of on-chip oscillators.

  13. Torque Production in a Halbach Machine

    NASA Technical Reports Server (NTRS)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.; Vrnak, Daniel R.

    2006-01-01

    The NASA John H. Glenn Research Center initiated the investigation of torque production in a Halbach machine for the Levitated Ducted Fan (LDF) Project to obtain empirical data in determining the feasibility of using a Halbach motor for the project. LDF is a breakthrough technology for "Electric Flight" with the development of a clean, quiet, electric propulsor system. Benefits include zero emissions, decreased dependence on fossil fuels, increased efficiency, increased reliability, reduced maintenance, and decreased operating noise levels. A commercial permanent magnet brushless motor rotor was tested with a custom stator. An innovative rotor utilizing a Halbach array was designed and developed to fit directly into the same stator. The magnets are oriented at 90deg to the adjacent magnet, which cancels the magnetic field on the inside of the rotor and strengthens the field on the outside of the rotor. A direct comparison of the commercial rotor and the Halbach rotor was made. In addition, various test models were designed and developed to validate the basic principles described, and the theoretical work that was performed. The report concludes that a Halbach array based motor can provide significant improvements in electric motor performance and reliability.

  14. Extraneous torque and compensation control on the electric load simulator

    NASA Astrophysics Data System (ADS)

    Jiao, Zongxia; Li, Chenggong; Ren, Zhiting

    2003-09-01

    In this paper a novel motor-drive load simulator based on compensation control strategy is proposed and designed. Through analyzing the torque control system consisting of DC torque motor, PWM module and torque sensor, it is shown that performance of the motor-drive load simulator is possible to be as good as that of the electro-hydraulic load simulator in the range of small torque. In the course of loading, the rotation of the actuator would cause a strong disturbance torque through the motor back-EMF, which produces extraneous torque similar as in electro-hydraulic load simulator. This paper analyzes the cause of extraneous torque inside the torque motor in detail and presents an appropriate compensation control with which the extraneous torque can be compensated and the good performance of the torque control system can be obtained. The results of simulation indicate that the compensation is very effective and the track performance is according with the request.

  15. VizieR Online Data Catalog: Planetary transit candidates in CoRoT LRa01 field (Carone+, 2012)

    NASA Astrophysics Data System (ADS)

    Carone, L.; Gandolfi, D.; Cabrera, J.; Hatzes, A. P.; Deeg, H. J.; Csizmadia, Sz.; Paetzold, M.; Weingrill, J.; Aigrain, S.; Alonso, R.; Alapini, A.; Almenara, J.-M.; Auvergne, M.; Baglin, A.; Barge, P.; Bonomo, A. S.; Borde, P.; Bouchy, F.; Bruntt, H.; Carpano, S.; Cochran, W. D.; Deleuil, M.; Diaz, R. F.; Dreizler, S.; Dvorak, R.; Eisloeffel, J.; Eigmueller, P.; Endl, M.; Erikson, A.; Ferraz-Mello, S.; Fridlund, M.; Gazzano, J.-C.; Gibson, N.; Gillon, M.; Gondoin, P.; Grziwa, S.; Guenther, E. W.; Guillot, T.; Hartmann, M.; Havel, M.; Hebrard, G.; Jorda, L.; Kabath, P.; Leger, A.; Llebaria, A.; Lammer, H.; Lovis, C.; MacQueen, P. J.; Mayor, M.; Mazeh, T.; Moutou, C.; Nortmann, L.; Ofir, A.; Ollivier, M.; Parviainen, H.; Pepe, F.; Pont, F.; Queloz, D.; Rabus, M.; Rauer, H.; Regulo, C.; Renner, S.; de La, Reza R.; Rouan, D.; Santerne, A.; Samuel, B.; Schneider, J.; Shporer, A.; Stecklum, B.; Tal-Or, L.; Tingley, B.; Udry, S.; Wuchterl, G.

    2012-04-01

    We present the list of planetary transit candidates from the CoRoT LRa01 star field in the Monoceros constellation toward the Galactic anti-center direction. The CoRoT observations of LRa01 lasted from 24 October 2007 to 3 March 2008. We acquired and analyzed 7470 chromatic and 3938 monochromatic lightcurves. Instrumental noise and stellar variability were treated with several filtering tools by different teams from the CoRoT community. Different transit search algorithms were applied to the lightcurves. (4 data files).

  16. The power of low-resolution spectroscopy: On the spectral classification of planet candidates in the ground-based CoRoT follow-up

    NASA Astrophysics Data System (ADS)

    Ammler-von Eiff, M.; Sebastian, D.; Guenther, E. W.; Stecklum, B.; Cabrera, J.

    2015-02-01

    Planetary transits detected by the CoRoT mission can be mimicked by a low-mass star in orbit around a giant star. Spectral classification helps to identify the giant stars and also early-type stars which are often excluded from further follow-up. We study the potential and the limitations of low-resolution spectroscopy to improve the photometric spectral types of CoRoT candidates. In particular, we want to study the influence of the signal-to-noise ratio (SNR) of the target spectrum in a quantitative way. We built an own template library and investigate whether a template library from the literature is able to reproduce the classifications. Including previous photometric estimates, we show how the additional spectroscopic information improves the constraints on spectral type. Low-resolution spectroscopy (R≈ 1000) of 42 CoRoT targets covering a wide range in SNR (1-437) and of 149 templates was obtained in 2012-2013 with the Nasmyth spectrograph at the Tautenburg 2 m telescope. Spectral types have been derived automatically by comparing with the observed template spectra. The classification has been repeated with the external CFLIB library. The spectral class obtained with the external library agrees within a few sub-classes when the target spectrum has a SNR of about 100 at least. While the photometric spectral type can deviate by an entire spectral class, the photometric luminosity classification is as close as a spectroscopic classification with the external library. A low SNR of the target spectrum limits the attainable accuracy of classification more strongly than the use of external templates or photometry. Furthermore we found that low-resolution reconnaissance spectroscopy ensures that good planet candidates are kept that would otherwise be discarded based on photometric spectral type alone.

  17. Force and torque modelling of drilling simulation for orthopaedic surgery.

    PubMed

    MacAvelia, Troy; Ghasempoor, Ahmad; Janabi-Sharifi, Farrokh

    2014-01-01

    The advent of haptic simulation systems for orthopaedic surgery procedures has provided surgeons with an excellent tool for training and preoperative planning purposes. This is especially true for procedures involving the drilling of bone, which require a great amount of adroitness and experience due to difficulties arising from vibration and drill bit breakage. One of the potential difficulties with the drilling of bone is the lack of consistent material evacuation from the drill's flutes as the material tends to clog. This clogging leads to significant increases in force and torque experienced by the surgeon. Clogging was observed for feed rates greater than 0.5 mm/s and spindle speeds less than 2500 rpm. The drilling simulation systems that have been created to date do not address the issue of drill flute clogging. This paper presents force and torque prediction models that account for this phenomenon. The two coefficients of friction required by these models were determined via a set of calibration experiments. The accuracy of both models was evaluated by an additional set of validation experiments resulting in average R² regression correlation values of 0.9546 and 0.9209 for the force and torque prediction models, respectively. The resulting models can be adopted by haptic simulation systems to provide a more realistic tactile output. PMID:23167723

  18. Isokinetic torque levels in hemophiliac knee musculature.

    PubMed

    Strickler, E M; Greene, W B

    1984-12-01

    The purposes of this study were to 1) measure peak torques generated by knee extensors and flexors in hemophilia patients; 2) describe flexor to extensor; 3) record the point in the arc of motion where peak torque was achieved; 4) correlate results with age, degree of hemophilic arthropathy, and presence of flexion contracture; and 5) compare results with reports on healthy subjects. Forty-seven patients (94 knees) with severe hemophilia were tested with a Cybex II isokinetic dynamometer at a speed of 30 degrees per second. Height, weight, thigh girths, and passive knee range of motion were recorded. Standing roentgenograms of the knee were evaluated to assess degree of arthropathy. Subjects were divided into groups by age and degree of arthropathy. Descriptive statistics were generated for all groups. Average peak extensor and flexor torque was similar for adolescents and adults. Increasing degree of arthropathy was associated with significant decreases in both extensor and flexor torque, an increase in flexor to extensor ratios and increasing knee flexion contractures. Across all groups, flexor to extensor ratios were abnormally high, particularly in patients with type IV arthropathy. The point in arc of motion where peak torques occurred did not differ significantly across groups and compared favorably with measures reported in the literature. For all ages, mean peak extensor and flexor torques were less than values reported in the literature for healthy subjects. Results of this study demonstrate the profound decrease in torque produced by knee musculature in hemophilia patients, particularly those with more severe arthropathy and knee flexion deformity.

  19. A Method to Accurately Estimate the Muscular Torques of Human Wearing Exoskeletons by Torque Sensors

    PubMed Central

    Hwang, Beomsoo; Jeon, Doyoung

    2015-01-01

    In exoskeletal robots, the quantification of the user’s muscular effort is important to recognize the user’s motion intentions and evaluate motor abilities. In this paper, we attempt to estimate users’ muscular efforts accurately using joint torque sensor which contains the measurements of dynamic effect of human body such as the inertial, Coriolis, and gravitational torques as well as torque by active muscular effort. It is important to extract the dynamic effects of the user’s limb accurately from the measured torque. The user’s limb dynamics are formulated and a convenient method of identifying user-specific parameters is suggested for estimating the user’s muscular torque in robotic exoskeletons. Experiments were carried out on a wheelchair-integrated lower limb exoskeleton, EXOwheel, which was equipped with torque sensors in the hip and knee joints. The proposed methods were evaluated by 10 healthy participants during body weight-supported gait training. The experimental results show that the torque sensors are to estimate the muscular torque accurately in cases of relaxed and activated muscle conditions. PMID:25860074

  20. A method to accurately estimate the muscular torques of human wearing exoskeletons by torque sensors.

    PubMed

    Hwang, Beomsoo; Jeon, Doyoung

    2015-04-09

    In exoskeletal robots, the quantification of the user's muscular effort is important to recognize the user's motion intentions and evaluate motor abilities. In this paper, we attempt to estimate users' muscular efforts accurately using joint torque sensor which contains the measurements of dynamic effect of human body such as the inertial, Coriolis, and gravitational torques as well as torque by active muscular effort. It is important to extract the dynamic effects of the user's limb accurately from the measured torque. The user's limb dynamics are formulated and a convenient method of identifying user-specific parameters is suggested for estimating the user's muscular torque in robotic exoskeletons. Experiments were carried out on a wheelchair-integrated lower limb exoskeleton, EXOwheel, which was equipped with torque sensors in the hip and knee joints. The proposed methods were evaluated by 10 healthy participants during body weight-supported gait training. The experimental results show that the torque sensors are to estimate the muscular torque accurately in cases of relaxed and activated muscle conditions.

  1. New Technique of High-Performance Torque Control Developed for Induction Machines

    NASA Technical Reports Server (NTRS)

    Kenny, Barbara H.

    2003-01-01

    Two forms of high-performance torque control for motor drives have been described in the literature: field orientation control and direct torque control. Field orientation control has been the method of choice for previous NASA electromechanical actuator research efforts with induction motors. Direct torque control has the potential to offer some advantages over field orientation, including ease of implementation and faster response. However, the most common form of direct torque control is not suitable for the highspeed, low-stator-flux linkage induction machines designed for electromechanical actuators with the presently available sample rates of digital control systems (higher sample rates are required). In addition, this form of direct torque control is not suitable for the addition of a high-frequency carrier signal necessary for the "self-sensing" (sensorless) position estimation technique. This technique enables low- and zero-speed position sensorless operation of the machine. Sensorless operation is desirable to reduce the number of necessary feedback signals and transducers, thus improving the reliability and reducing the mass and volume of the system. This research was directed at developing an alternative form of direct torque control known as a "deadbeat," or inverse model, solution. This form uses pulse-width modulation of the voltage applied to the machine, thus reducing the necessary sample and switching frequency for the high-speed NASA motor. In addition, the structure of the deadbeat form allows the addition of the high-frequency carrier signal so that low- and zero-speed sensorless operation is possible. The new deadbeat solution is based on using the stator and rotor flux as state variables. This choice of state variables leads to a simple graphical representation of the solution as the intersection of a constant torque line with a constant stator flux circle. Previous solutions have been expressed only in complex mathematical terms without a

  2. Gyrokinetic simulations with external resonant magnetic perturbations: Island torque and nonambipolar transport with plasma rotation

    NASA Astrophysics Data System (ADS)

    Waltz, R. E.; Waelbroeck, F. L.

    2012-03-01

    Static external resonant magnetic field perturbations (RMPs) have been added to the gyrokinetic code GYRO [J. Candy and R. E. Waltz, J. Comp. Phys. 186, 545 (2003)]. This allows nonlinear gyrokinetic simulations of the nonambipolar radial current flow jr, and the corresponding j→×B→ plasma torque (density) R[jrBp/c], induced by magnetic islands that break the toroidal symmetry of a tokamak. This extends the previous GYRO formulation for the transport of toroidal angular momentum (TAM) [R. E. Waltz, G. M. Staebler, J. Candy, and F. L. Hinton, Phys. Plasmas 14, 122507 (2007); errata 16, 079902 (2009)]. The focus is on electrostatic full torus radial slice simulations of externally induced q =m/n=6/3 islands with widths 5% of the minor radius or about 20 ion gyroradii. Up to moderately strong E ×B rotation, the island torque scales with the radial electric field at the resonant surface Er, the island width w, and the intensity I of the high-n micro-turbulence, as Erw√I . The radial current inside the island is carried (entirely in the n =3 component) and almost entirely by the ion E ×B flux, since the electron E ×B and magnetic flutter particle fluxes are cancelled. The net island torque is null at zero Er rather than at zero toroidal rotation. This means that while the expected magnetic braking of the toroidal plasma rotation occurs at strong co- and counter-current rotation, at null toroidal rotation, there is a small co-directed magnetic acceleration up to the small diamagnetic (ion pressure gradient driven) co-rotation corresponding to the zero Er and null torque. This could be called the residual stress from an externally induced island. At zero Er, the only effect is the expected partial flattening of the electron temperature gradient within the island. Finite-beta GYRO simulations demonstrate almost complete RMP field screening and n =3 mode unlocking at strong Er.

  3. Self-oscillation in spin torque oscillator stabilized by field-like torque

    SciTech Connect

    Taniguchi, Tomohiro; Tsunegi, Sumito; Kubota, Hitoshi; Imamura, Hiroshi

    2014-04-14

    The effect of the field-like torque on the self-oscillation of the magnetization in spin torque oscillator with a perpendicularly magnetized free layer was studied theoretically. A stable self-oscillation at zero field is excited for negative β while the magnetization dynamics stops for β = 0 or β > 0, where β is the ratio between the spin torque and the field-like torque. The reason why only the negative β induces the self-oscillation was explained from the view point of the energy balance between the spin torque and the damping. The oscillation power and frequency for various β were also studied by numerical simulation.

  4. Electro-orientation of a metal nanowire counterbalanced by thermal torques

    NASA Astrophysics Data System (ADS)

    Arcenegui, Juan J.; García-Sánchez, Pablo; Morgan, Hywel; Ramos, Antonio

    2014-06-01

    The rotational diffusion of electrically polarized metal nanowires suspended in an electrolyte is studied. The alignment of a Brownian nanowire in an ac field with a given direction is not complete due to thermal (fluctuating) torques. The orientation distribution allows us to examine the electrokinetic torques acting on the nanowire for smaller voltages than in previous deterministic experiments. In addition, the torques are obtained without recurring to the rotational friction coefficient as in dynamic deterministic experiments. The present results are in accordance with previous deterministic results of electro-orientation of metal nanowires. Nanowire rotation is originated by both the electrical torque on the induced dipole and by induced-charge electro-osmotic flow around the particle. At low frequencies of the applied ac field, induced-charge electro-osmotic orientation dominates while induced dipole torque orientation dominates at high frequencies. The angular standard deviation and the rotational rate are calculated from the measured fluctuating angle as a function of time, and good agreement with theoretical predictions is found. The experiments at high frequency indicate that the electrical torque on a nanowire near an insulating wall is reduced with respect to the bulk.

  5. Muscle torque of healthy individuals and individuals with spastic hemiparesis after passive static streching.

    PubMed

    Tatsukawa DE Freitas, Sérgio Takeshi; DE Carvalho Abreu, Elizângela Márcia; Dos Reis, Mariane Cecilia; DE Souza Cunha, Bruna; Souza Moreira Prianti, Tamires; Pupio Silva Lima, Fernanda; Oliveira Lima, Mário

    2016-01-01

    Spasticity is one of the main causes of contracture, muscle weakness and subsequent functional incapacity. The passive static stretching can be included as having the purpose of increasing musculoskeletal flexibility, however, it also can influence the muscle torque. The objective is to verify the immediate effect of passive static stretching in the muscle strength of healthy and those who present spastic hemiparesis. There were assessed 20 subjects, 10 spastic hemiparetic (EG) and 10 healthy individuals (CG), including both sexes, aged between 22 and 78 years. The torque of extensor muscles of the knee was analyzed using isokinetic dynamometer. Results have shown that EG has less muscle torque compared to CG ( p < 0.01). In addition, EG presented a decrease in significance of muscle torque after stretching ( p < 0.05), however, it has not shown significant alteration in muscle torque of CG after performing the program that was prescribed. Immediately after the passive stretch, a significant torque decrease can be seen in hypertonic muscle; it is believed that this reduction may be associated with the physiological overlap between actin and myosin filaments and so preventing the muscle to develop a maximum contraction. PMID:27151602

  6. Electro-orientation of a metal nanowire counterbalanced by thermal torques.

    PubMed

    Arcenegui, Juan J; García-Sánchez, Pablo; Morgan, Hywel; Ramos, Antonio

    2014-06-01

    The rotational diffusion of electrically polarized metal nanowires suspended in an electrolyte is studied. The alignment of a Brownian nanowire in an ac field with a given direction is not complete due to thermal (fluctuating) torques. The orientation distribution allows us to examine the electrokinetic torques acting on the nanowire for smaller voltages than in previous deterministic experiments. In addition, the torques are obtained without recurring to the rotational friction coefficient as in dynamic deterministic experiments. The present results are in accordance with previous deterministic results of electro-orientation of metal nanowires. Nanowire rotation is originated by both the electrical torque on the induced dipole and by induced-charge electro-osmotic flow around the particle. At low frequencies of the applied ac field, induced-charge electro-osmotic orientation dominates while induced dipole torque orientation dominates at high frequencies. The angular standard deviation and the rotational rate are calculated from the measured fluctuating angle as a function of time, and good agreement with theoretical predictions is found. The experiments at high frequency indicate that the electrical torque on a nanowire near an insulating wall is reduced with respect to the bulk.

  7. Prevailing Torque Locking Feature Wear-out

    NASA Astrophysics Data System (ADS)

    Zimandy, Adam J. C.

    This thesis provides much needed representative sample data for reuse life of fully seated and torqued locknuts. Most national requirements for prevailing torque locking fasteners only specify unseated reuse life. This could create a potentially dangerous situation if unseated is misinterpreted for seated. This thesis provides comparative data for seated verses unseated configuration. Six aerospace, 3 all-metal and 3 nylon insert, and one non-aerospace locknuts were tested at preloads levels of unseated, 66%, 75%, and 85% of yield of bolt. The locknuts tested are MS21043-4, NAS1291-4, NAS1805-4, MS17825-4, MS21044D4, NAS1021N4, and Grade 8. A fixture was created in order to allow for the simultaneous data collection of the applied preload and torque, along with the removal of preload without loosening the locknut. The results from testing indicate the number of reuse cycles is greater for nylon locknuts than the all-metal locknuts. Large losses, on the order of 20-50%, in prevailing torque occur between the first and second cycle of each locknut under all preloads. Tightening Torque required to achieve a certain preload was found to increase with reuse. Application of lubrication to nylon locknuts had a significant effect, reducing the reuse life and prevailing torque performance. The testing indicated the effect of preload reduced the number of reuse cycles to failure, failure occurs when the prevailing torque is measured outside the range of 3.5 to 30 in-lb. All locknuts survived unseated and 66% Y preload testing, except MS21043 which lasted about 14.5 reuse cycles at 66% Y and NAS1805 which survived 8 reuse cycles for unseated and 12.67 reuse cycles at 66% Y. NAS1805's loss of reuse life is due to hardness and material compatibility issues. The scatter of the torque measurements was low for the first three to five cycles, then as the coatings and lubrications are worn the scatter increases. The data collected from testing agrees with the torque friction

  8. Feasibility of estimating isokinetic knee torque using a neural network model.

    PubMed

    Hahn, Michael E

    2007-01-01

    Many studies have investigated the relationships between electromyography (EMG) and torque production. A few investigators have used adjusted learning algorithms and feed-forward artificial neural networks (ANNs) to estimate joint torque in the elbow. This study sought to estimate net isokinetic knee torque using ANN models. Isokinetic knee extensor and flexor torque data were measured simultaneously with agonist and antagonist EMG during concentric and eccentric contractions at joint velocities of 30 degrees /s and 60 degrees /s. Age, gender, height, body mass, agonist EMG, antagonist EMG, joint position and joint velocity were entered as predictive variables of net torque. A three-layer ANN model was developed and trained using an adjusted back-propagation algorithm. Accuracy results were compared against those of forward stepwise regression models. Stepwise regression models included body mass, body height and joint position as the most influential predictors, followed by agonist EMG for concentric and eccentric contractions. Estimation of eccentric torque included antagonist EMG following the agonist activation. ANN models resulted in more accurate torque estimation (R=0.96), compared to the stepwise regression models (R=0.71). ANN model accuracy increased greatly when the number of hidden units increased from 5 to 10, continuing to increase gradually with additional hidden units. The average number of training epochs necessary for solution convergence and the relative accuracy of the model indicate a strong ability for the ANN model to generalize these estimations to a broader sample. The ANN model appears to be a feasible technique for estimating joint torque in the knee.

  9. Measurement and analysis of instantaneous torque and angular velocity variations of a low speed two stroke diesel engine

    NASA Astrophysics Data System (ADS)

    Jiménez Espadafor, Francisco J.; A. Becerra Villanueva, José; Palomo Guerrero, Daniel; Torres García, Miguel; Carvajal Trujillo, Elisa; Fernández Vacas, Francisco

    2014-12-01

    This paper presents an investigation into the potential of using direct measurement of engine torque for diagnostic purposes in large engines - in this case applied to power generation. The procedures for measuring and analyzing the instantaneous torque, the angular displacement on the generator output end and the angular displacement on its free end for a ten-cylinder, low speed two stroke diesel engine are presented. Angular speed oscillations are frequently used for combustion engine diagnostics although they cannot be used to measure engine power directly. In addition, and for engines with huge inertia generators such as those used in power plants, speed oscillations are very low and this reduces the signal to noise ratio and makes the evaluation of the instantaneous angular speed very noisy. In the work described here, torque and angular displacement measurements carried out at the same point and with the same engine conditions are compared and the superior performance of torque is demonstrated. Harmonic analysis of instantaneous torque allowed the identification of the dynamic characteristics of the power train of the diesel group and clearly suggests that this signal can be used as a diagnostic tool for excitation, combustion malfunctions, or for the mechanical characteristics of the system and crankshaft stiffness. The torque distortion introduced by the generator due to the discontinuity imposed by the pole pairs is also observed in the torque signal, suggesting that the torque signal can be used to identify generator malfunction.

  10. Torque shudder protection device and method

    DOEpatents

    King, R.D.; Doncker, R.W.A.A. De.; Szczesny, P.M.

    1997-03-11

    A torque shudder protection device for an induction machine includes a flux command generator for supplying a steady state flux command and a torque shudder detector for supplying a status including a negative status to indicate a lack of torque shudder and a positive status to indicate a presence of torque shudder. A flux adapter uses the steady state flux command and the status to supply a present flux command identical to the steady state flux command for a negative status and different from the steady state flux command for a positive status. A limiter can receive the present flux command, prevent the present flux command from exceeding a predetermined maximum flux command magnitude, and supply the present flux command to a field oriented controller. After determining a critical electrical excitation frequency at which a torque shudder occurs for the induction machine, a flux adjuster can monitor the electrical excitation frequency of the induction machine and adjust a flux command to prevent the monitored electrical excitation frequency from reaching the critical electrical excitation frequency. 5 figs.

  11. Torque shudder protection device and method

    DOEpatents

    King, Robert D.; De Doncker, Rik W. A. A.; Szczesny, Paul M.

    1997-01-01

    A torque shudder protection device for an induction machine includes a flux command generator for supplying a steady state flux command and a torque shudder detector for supplying a status including a negative status to indicate a lack of torque shudder and a positive status to indicate a presence of torque shudder. A flux adapter uses the steady state flux command and the status to supply a present flux command identical to the steady state flux command for a negative status and different from the steady state flux command for a positive status. A limiter can receive the present flux command, prevent the present flux command from exceeding a predetermined maximum flux command magnitude, and supply the present flux command to a field oriented controller. After determining a critical electrical excitation frequency at which a torque shudder occurs for the induction machine, a flux adjuster can monitor the electrical excitation frequency of the induction machine and adjust a flux command to prevent the monitored electrical excitation frequency from reaching the critical electrical excitation frequency.

  12. Force, Torque and Stiffness: Interactions in Perceptual Discrimination

    PubMed Central

    Wu, Bing; Klatzky, Roberta L.; Hollis, Ralph L.

    2011-01-01

    Three experiments investigated whether force and torque cues interact in haptic discrimination of force, torque and stiffness, and if so, how. The statistical relation between force and torque was manipulated across four experimental conditions: Either one type of cue varied while the other was constant, or both varied so as to be positively correlated, negatively correlated, or uncorrelated. Experiment 1 showed that the subjects’ ability to discriminate force was improved by positively correlated torque but impaired with uncorrelated torque, as compared to the constant torque condition. Corresponding effects were found in Experiment 2 for the influence of force on torque discrimination. These findings indicate that force and torque are integrated in perception, rather than being processed as separate dimensions. A further experiment demonstrated facilitation of stiffness discrimination by correlated force and torque, whether the correlation was positive or negative. The findings suggest new means of augmenting haptic feedback to facilitate perception of the properties of soft objects. PMID:21359137

  13. Thomas precession: Where is the torque

    SciTech Connect

    Muller, R.A. )

    1992-04-01

    Special relativity appears to violate the conservation of angular momentum {bold L} since it predicts that an accelerated gyroscope will precess, i.e., {bold L} will change in the absence of any applied torque. The paradox is resolved in a simple example by demonstrating that there is a torque present. The mass distribution in the gyroscope undergoes a relativistic distortion, and the center of mass is displaced away from the position of the accelerating force. The resulting torque {tau}={ital d}{bold L}/{ital dt}. The model also shows the physical origins of spin-orbit coupling and of the oscillating term.'' A related calculation shows why a moving magnetic dipole has an {ital electric} dipole moment.

  14. Variable Torque Prescription: State of Art.

    PubMed Central

    Lacarbonara, Mariano; Accivile, Ettore; Abed, Maria R.; Dinoi, Maria Teresa; Monaco, Annalisa; Marzo, Giuseppe; Capogreco, Mario

    2015-01-01

    The variable prescription is widely described under the clinical aspect: the clinics is the result of the evolution of the state-of-the-art, aspect that is less considered in the daily literature. The state-of-the-art is the key to understand not only how we reach where we are but also to learn how to manage propely the torque, focusing on the technical and biomechanical purpos-es that led to the change of the torque values over time. The aim of this study is to update the clinicians on the aspects that affect the torque under the biomechanical sight, helping them to understand how to managing it, following the “timeline changes” in the different techniques so that the Variable Prescription Orthodontic (VPO) would be a suitable tool in every clinical case. PMID:25674173

  15. Visual influence on haptic torque perception.

    PubMed

    Xu, Yangqing; O'Keefe, Shélan; Suzuki, Satoru; Franconeri, Steven L

    2012-01-01

    The brain receives input from multiple sensory modalities simultaneously, yet we experience the outside world as a single integrated percept. This integration process must overcome instances where perceptual information conflicts across sensory modalities. Under such conflicts, the relative weighting of information from each modality typically depends on the given task. For conflicts between visual and haptic modalities, visual information has been shown to influence haptic judgments of object identity, spatial features (e.g., location, size), texture, and heaviness. Here we test a novel instance of haptic-visual conflict in the perception of torque. We asked participants to hold a left-right unbalanced object while viewing a potentially left-right mirror-reversed image of the object. Despite the intuition that the more proximal haptic information should dominate the perception of torque, we find that visual information exerts substantial influences on torque perception even when participants know that visual information is unreliable.

  16. AX-5 space suit bearing torque investigation

    NASA Technical Reports Server (NTRS)

    Loewenthal, Stuart; Vykukal, Vic; Mackendrick, Robert; Culbertson, Philip, Jr.

    1990-01-01

    The symptoms and eventual resolution of a torque increase problem occurring with ball bearings in the joints of the AX-5 space suit are described. Starting torques that rose 5 to 10 times initial levels were observed in crew evaluation tests of the suit in a zero-g water tank. This bearing problem was identified as a blocking torque anomaly, observed previously in oscillatory gimbal bearings. A large matrix of lubricants, ball separator designs and materials were evaluated. None of these combinations showed sufficient tolerance to lubricant washout when repeatedly cycled in water. The problem was resolved by retrofitting a pressure compensated, water exclusion seal to the outboard side of the bearing cavity. The symptoms and possible remedies to blocking are discussed.

  17. Global regularity for the 2D Oldroyd-B model in the corotational case

    NASA Astrophysics Data System (ADS)

    Ye, Zhuan; Xu, Xiaojing

    2016-09-01

    This paper is dedicated to the Oldroyd-B model with fractional dissipation $(-\\Delta)^{\\alpha}\\tau$ for any $\\alpha>0$. We establish the global smooth solutions to the Oldroyd-B model in the corotational case with arbitrarily small fractional powers of the Laplacian in two spatial dimensions. The methods described here are quite different from the tedious iterative approach used in recent paper \\cite{XY}. Moreover, in the Appendix we provide some a priori estimates to the Oldroyd-B model in the critical case which may be useful and of interest for future improvement. Finally, the global regularity to to the Oldroyd-B model in the corotational case with $-\\Delta u$ replaced by $(-\\Delta)^{\\gamma}u$ for $\\gamma>1$ are also collected in the Appendix. Therefore our result is more closer to the resolution of the well-known global regularity issue on the critical 2D Oldroyd-B model.

  18. Stellar parameters for stars of the CoRoT exoplanet field

    NASA Astrophysics Data System (ADS)

    Cortés, C.; Maciel, S. C.; Vieira, S.; Ferreira Lopes, C. E.; Leão, I. C.; de Oliveira, G. P.; Correia, C.; Canto Martins, B. L.; Catelan, M.; De Medeiros, J. R.

    2015-09-01

    Context. Spectroscopic observations represent a fundamental step in the physical characterization of stars and, in particular, in the precise location of stars in the HR diagram. Rotation is also a key parameter, impacting stellar properties and evolution, which modulates the interior and manifests itself on the surface of stars. To date, the lack of analysis based on large samples has prevented our understanding of the real impact of stellar parameters and rotation on the stellar evolution as well as on the behavior of surface abundances. The space missions, CoRoT and Kepler, are providing us with rotation periods for thousands of stars, thus enabling a robust assessment of the behavior of rotation for different populations and evolutionary stages. For these reasons, the follow-up programs are fundamental to increasing the returns of these space missions. An analysis that combines spectroscopic data and rotation/modulation periods obtained from these space missions provides the basis for establishing the evolutionary behavior of the angular momentum of solar-like stars at different evolutionary stages, and the relation of rotation with other relevant physical and chemical parameters. Aims: To support the computation and evolutionary interpretation of periods associated with the rotational modulation, oscillations, and variability of stars located in the CoRoT fields, we are conducting a spectroscopic survey for stars located in the fields already observed by the satellite. These observations allow us to compute physical and chemical parameters for our stellar sample. Methods: Using spectroscopic observations obtained with UVES/VLT and Hydra/Blanco, and based on standard analysis techniques, we computed physical and chemical parameters (Teff, log (g), [Fe/H], vmic, vrad, vsin (i), and A(Li)) for a large sample of CoRoT targets. Results: We provide physical and chemical parameters for a sample comprised of 138 CoRoT targets. Our analysis shows the stars in our

  19. Observed departure of the Io plasma torus from rigid corotation with Jupiter

    NASA Technical Reports Server (NTRS)

    Brown, R. A.

    1983-01-01

    A study of forbidden S II red doublet spectra indicates that the Io plasma torus at 5.9 Jupiter radii does not corotate rigidly with Jupiter. The lag is found to be 6 percent + or 4 percent, where the variability range, not the uncertainty, is indicated. Comparison with existing models indicates the lag may be due primarily to ion creation in the Io torus.

  20. A rotating Michelson interferometer from the co-rotating point of view

    NASA Astrophysics Data System (ADS)

    Maraner, Paolo

    2016-06-01

    The phase shift induced by a uniform rotation in a Michelson interferometer is re-derived in the geometrical framework of the coordinate-free formalism of general relativity from the co-rotating point of view. The effect is second order in the ratio of the interferometer's speed to the speed of light and further suppressed by the ratio of the length of the interferometer's arms to the radius of rotation. The relation of the effect to gravitational time dilation is discussed.

  1. Improved Variable Star Search in Large Photometric Data Sets: New Variables in CoRoT Field LRa02 Detected by BEST II

    NASA Astrophysics Data System (ADS)

    Fruth, T.; Kabath, P.; Cabrera, J.; Chini, R.; Csizmadia, Sz.; Eigmüller, P.; Erikson, A.; Kirste, S.; Lemke, R.; Murphy, M.; Pasternacki, T.; Rauer, H.; Titz-Weider, R.

    2012-06-01

    The CoRoT field LRa02 has been observed with the Berlin Exoplanet Search Telescope II (BEST II) during the southern summer 2007/2008. A first analysis of stellar variability led to the publication of 345 newly discovered variable stars. Now, a deeper analysis of this data set was used to optimize the variability search procedure. Several methods and parameters have been tested in order to improve the selection process compared to the widely used J index for variability ranking. This paper describes an empirical approach to treat systematic trends in photometric data based upon the analysis of variance statistics that can significantly decrease the rate of false detections. Finally, the process of reanalysis and method improvement has virtually doubled the number of variable stars compared to the first analysis by Kabath et al. A supplementary catalog of 272 previously unknown periodic variables plus 52 stars with suspected variability is presented. Improved ephemerides are given for 19 known variables in the field. In addition, the BEST II results are compared with CoRoT data and its automatic variability classification.

  2. IMPROVED VARIABLE STAR SEARCH IN LARGE PHOTOMETRIC DATA SETS: NEW VARIABLES IN CoRoT FIELD LRa02 DETECTED BY BEST II

    SciTech Connect

    Fruth, T.; Cabrera, J.; Csizmadia, Sz.; Eigmueller, P.; Erikson, A.; Kirste, S.; Pasternacki, T.; Rauer, H.; Titz-Weider, R.; Kabath, P.; Chini, R.; Lemke, R.; Murphy, M.

    2012-06-15

    The CoRoT field LRa02 has been observed with the Berlin Exoplanet Search Telescope II (BEST II) during the southern summer 2007/2008. A first analysis of stellar variability led to the publication of 345 newly discovered variable stars. Now, a deeper analysis of this data set was used to optimize the variability search procedure. Several methods and parameters have been tested in order to improve the selection process compared to the widely used J index for variability ranking. This paper describes an empirical approach to treat systematic trends in photometric data based upon the analysis of variance statistics that can significantly decrease the rate of false detections. Finally, the process of reanalysis and method improvement has virtually doubled the number of variable stars compared to the first analysis by Kabath et al. A supplementary catalog of 272 previously unknown periodic variables plus 52 stars with suspected variability is presented. Improved ephemerides are given for 19 known variables in the field. In addition, the BEST II results are compared with CoRoT data and its automatic variability classification.

  3. A Model for Plasma Transport in a Corotation-Dominated Magnetosphere.

    NASA Astrophysics Data System (ADS)

    Pontius, Duane Henry, Jr.

    1988-06-01

    The gross structures of the magnetospheres of the outer planets are decided by processes quite different from those predominant in that of the earth. The terrestrial plasmapause, the boundary beyond which plasma motion is principally determined by magnetospheric interaction with the solar wind, is typically inside geosynchronous orbit. Within the plasmasphere, rotational effects are present, but gravity exceeds the centrifugal force of corotation. In contrast, the Jovian plasmasphere extends to a distance at least twenty times farther than synchronous orbit, affording a large region where rotational effects are expected to he clearly manifest (Brice and Ioannidis, 1970). The goal of this thesis is to develop an appropriate theoretical model for treating the problem of plasma transport in a corotation dominated plasmasphere. The model presented here is intended to describe the radial transport of relatively cold plasma having an azimuthally uniform distribution in a dipolar magnetic field. The approach is conceptually similar to that of the radial diffusion model in that small scale motions are examined to infer global consequences, but the physical understanding of those small scale motions is quite different. In particular, discrete flux tubes of small cross section are assumed to move over distances large compared to their widths. The present model also differs from the corotating convection model by introducing a mechanism whereby the conservation of flux tube content along flowlines is violated. However, it is quite possible that a global convection pattern co -exists with the motions described here, leading to longitudinal asymmetries in the plasma distribution.

  4. THE CoRoT DISCOVERY OF A UNIQUE TRIPLE-MODE CEPHEID IN THE GALAXY

    SciTech Connect

    Poretti, E.; Baglin, A.; Weiss, W. W.

    2014-11-10

    The exploitation of the CoRoT treasure of stars observed in the exoplanetary field allowed the detection of a unusual triple-mode Cepheid in the Milky Way, CoRoT 0223989566. The two modes with the largest amplitudes and a period ratio of 0.80 are identified with the first (P {sub 1} = 1.29 days) and second (P {sub 2} = 1.03 days) radial overtones. The third period, which has the smallest amplitude but is able to produce combination terms with the other two, is the longest one (P {sub 3} = 1.89 days). The ratio of 0.68 between the first-overtone period and the third period is the unusual feature. Its identification with the fundamental radial or a nonradial mode is discussed with respect to similar cases in the Magellanic Clouds. In both cases, the period triplet and the respective ratios make the star unique in our Galaxy. The distance derived from the period-luminosity relation and the galactic coordinates put CoRoT 0223989566 in the metal-rich environment of the ''outer arm'' of the Milky Way.

  5. Corotation resonance and overstable oscillations in black hole accretion discs: general relativistic calculations

    NASA Astrophysics Data System (ADS)

    Horák, Jiří; Lai, Dong

    2013-10-01

    We study the dynamics of spiral waves and oscillation modes in relativistic rotating discs around black holes. Generalizing the Newtonian theory, we show that wave absorption can take place at the corotation resonance, where the pattern frequency of the wave matches the background disc rotation rate. We derive the general relativistic expression for the disc vortensity (vorticity divided by surface density), which governs the behaviour of density perturbation near corotation. Depending on the gradient of the generalized disc vortensity, corotational wave absorption can lead to the amplification or damping of the spiral wave. We apply our general theory of relativistic wave dynamics to calculate the non-axisymmetric inertial-acoustic modes (also called p modes) trapped in the innermost region of a black hole accretion disc. Because general relativity changes the profiles of the radial epicyclic frequency and disc vortensity near the inner disc edge close to the black hole, these p modes can become overstable under appropriate conditions. We present the numerical results of the frequencies and growth rates of p modes for various black hole spin and model disc parameters (the surface density profile and sound speed), and discuss their implications for understanding the enigmatic high-frequency quasi-periodic oscillations observed in black hole X-ray binaries.

  6. A theoretical perspective on the ultra-compact systems of CoRoT and Kepler

    NASA Astrophysics Data System (ADS)

    Wuchterl, G.

    2011-10-01

    CoRoT and Kepler discovered closely spaced short period planetary systems. We investigate into the physics of these systems by combining an approach that was developed for the CoRoT mission to determine the distributions of planetary masses and radii based on a minimum number of basic physical principles with the classical approach of Hill-exclusion volumes to estimate dynamical stability. We discuss to what extent the discovered systems can be understood as a random draw from the theoretical mass and/or radius distributions with Hill-exclusion stability as a constraint. We point to the bi-modality of the theoretical planetary mass-function as a key factor in shaping the architecture of the presently known systems. Given the first-time availability of new high-resolution epoch-of observation theoretical radius distributions for the entire present period sensitivity of CoRoT and Keplerreleases, we take the opportunity to confront the various radius anomalies — 'styrofoam' planets, inflated Jupiters and Neptunes — to our statistical approach.

  7. Torque limit of PM motors for field-weakening region operation

    DOEpatents

    Royak, Semyon; Harbaugh, Mark M.

    2012-02-14

    The invention includes a motor controller and technique for controlling a permanent magnet motor. In accordance with one aspect of the present technique, a permanent magnet motor is controlled by receiving a torque command, determining a physical torque limit based on a stator frequency, determining a theoretical torque limit based on a maximum available voltage and motor inductance ratio, and limiting the torque command to the smaller of the physical torque limit and the theoretical torque limit. Receiving the torque command may include normalizing the torque command to obtain a normalized torque command, determining the physical torque limit may include determining a normalized physical torque limit, determining a theoretical torque limit may include determining a normalized theoretical torque limit, and limiting the torque command may include limiting the normalized torque command to the smaller of the normalized physical torque limit and the normalized theoretical torque limit.

  8. BEER analysis of Kepler and CoRoT light curves. III. Spectroscopic confirmation of seventy new beaming binaries discovered in CoRoT light curves

    NASA Astrophysics Data System (ADS)

    Tal-Or, L.; Faigler, S.; Mazeh, T.

    2015-08-01

    Context. The BEER algorithm searches stellar light curves for the BEaming, Ellipsoidal, and Reflection photometric modulations that are caused by a short-period companion. These three effects are typically of very low amplitude and can mainly be detected in light curves from space-based photometers. Unlike eclipsing binaries, these effects are not limited to edge-on inclinations. Aims: Applying the algorithm to wide-field photometric surveys such as CoRoT and Kepler offers an opportunity to better understand the statistical properties of short-period binaries. It also widens the window for detecting intrinsically rare systems, such as short-period brown-dwarf and massive-planetary companions to main-sequence stars. Methods: Applying the search to the first five long-run center CoRoT fields, we identified 481 non-eclipsing candidates with periodic flux amplitudes of 0.5-87 mmag. Optimizing the Anglo-Australian-Telescope pointing coordinates and the AAOmega fiber-allocations with dedicated softwares, we acquired six spectra for 231 candidates and seven spectra for another 50 candidates in a seven-night campaign. Analysis of the red-arm AAOmega spectra, which covered the range of 8342-8842 Å, yielded a radial-velocity precision of ~1 km s-1. Spectra containing lines of more than one star were analyzed with the two-dimensional correlation algorithm TODCOR. Results: The measured radial velocities confirmed the binarity of seventy of the BEER candidates - 45 single-line binaries, 18 double-line binaries, and 7 diluted binaries. We show that red giants introduce a major source of false candidates and demonstrate a way to improve BEER's performance in extracting higher fidelity samples from future searches of CoRoT light curves. The periods of the confirmed binaries span a range of 0.3-10 days and show a rise in the number of binaries per ΔlogP toward longer periods. The estimated mass ratios of the double-line binaries and the mass ratios assigned to the single

  9. WR 110: A SINGLE WOLF-RAYET STAR WITH COROTATING INTERACTION REGIONS IN ITS WIND?

    SciTech Connect

    Chene, A.-N.; Moffat, A. F. J.; Fahed, R.; St-louis, N.; Muntean, V.; Chevrotiere, A. De La; Cameron, C.; Matthews, J. M.; Gamen, R. C.; Rowe, J. F.; Guenther, D. B.; Kuschnig, R.; Weiss, W. W.; Rucinski, S. M.; Sasselov, D. E-mail: moffat@astro.umontreal.ca

    2011-07-01

    A 30 day contiguous photometric run with the Microvariability and Oscillations of STars (MOST) satellite on the WN5-6b star WR 110 (HD 165688) reveals a fundamental periodicity of P = 4.08 {+-} 0.55 days along with a number of harmonics at periods P/n, with n {approx} 2, 3, 4, 5, and 6, and a few other possible stray periodicities and/or stochastic variability on timescales longer than about a day. Spectroscopic radial velocity studies fail to reveal any plausible companion with a period in this range. Therefore, we conjecture that the observed light-curve cusps of amplitude {approx}0.01 mag that recur at a 4.08 day timescale may arise in the inner parts, or at the base, of a corotating interaction region (CIR) seen in emission as it rotates around with the star at constant angular velocity. The hard X-ray component seen in WR 110 could then be a result of a high velocity component of the CIR shock interacting with the ambient wind at several stellar radii. Given that most hot, luminous stars showing CIRs have two CIR arms, it is possible that either the fundamental period is 8.2 days or, more likely in the case of WR 110, there is indeed a second weaker CIR arm for P = 4.08 days, that occurs {approx}two-thirds of a rotation period after the main CIR. If this interpretation is correct, WR 110 therefore joins the ranks with three other single WR stars, all WN, with confirmed CIR rotation periods (WR 1, WR 6, and WR 134), albeit with WR 110 having by far the lowest amplitude photometric modulation. This illustrates the power of being able to secure intense, continuous high-precision photometry from space-based platforms such as MOST. It also opens the door to revealing low-amplitude photometric variations in other WN stars, where previous attempts have failed. If all WN stars have CIRs at some level, this could be important for revealing sources of magnetism or pulsation in addition to rotation periods.

  10. WR 110: A Single Wolf-Rayet Star with Corotating Interaction Regions in its Wind?

    NASA Astrophysics Data System (ADS)

    Chené, A.-N.; Moffat, A. F. J.; Cameron, C.; Fahed, R.; Gamen, R. C.; Lefèvre, L.; Rowe, J. F.; St-louis, N.; Muntean, V.; De La Chevrotière, A.; Guenther, D. B.; Kuschnig, R.; Matthews, J. M.; Rucinski, S. M.; Sasselov, D.; Weiss, W. W.

    2011-07-01

    A 30 day contiguous photometric run with the Microvariability and Oscillations of STars (MOST) satellite on the WN5-6b star WR 110 (HD 165688) reveals a fundamental periodicity of P = 4.08 ± 0.55 days along with a number of harmonics at periods P/n, with n ≈ 2, 3, 4, 5, and 6, and a few other possible stray periodicities and/or stochastic variability on timescales longer than about a day. Spectroscopic radial velocity studies fail to reveal any plausible companion with a period in this range. Therefore, we conjecture that the observed light-curve cusps of amplitude ~0.01 mag that recur at a 4.08 day timescale may arise in the inner parts, or at the base, of a corotating interaction region (CIR) seen in emission as it rotates around with the star at constant angular velocity. The hard X-ray component seen in WR 110 could then be a result of a high velocity component of the CIR shock interacting with the ambient wind at several stellar radii. Given that most hot, luminous stars showing CIRs have two CIR arms, it is possible that either the fundamental period is 8.2 days or, more likely in the case of WR 110, there is indeed a second weaker CIR arm for P = 4.08 days, that occurs ~two-thirds of a rotation period after the main CIR. If this interpretation is correct, WR 110 therefore joins the ranks with three other single WR stars, all WN, with confirmed CIR rotation periods (WR 1, WR 6, and WR 134), albeit with WR 110 having by far the lowest amplitude photometric modulation. This illustrates the power of being able to secure intense, continuous high-precision photometry from space-based platforms such as MOST. It also opens the door to revealing low-amplitude photometric variations in other WN stars, where previous attempts have failed. If all WN stars have CIRs at some level, this could be important for revealing sources of magnetism or pulsation in addition to rotation periods. Based on data from the MOST satellite, a Canadian Space Agency mission, jointly

  11. VizieR Online Data Catalog: Limb-darkening for CoRoT, Kepler, Spitzer (Claret+, 2012)

    NASA Astrophysics Data System (ADS)

    Claret, A.; Hauschildt, P. H.; Witte, S.

    2012-09-01

    The knowledge of how the specific intensity is distributed over the stellar disk is crucial for interpreting the light curves of extrasolar transiting planets, double-lined eclipsing binaries, and other astrophysical phenomena. To provide theoretical inputs for light curve modelling codes, we present new calculations of limb-darkening coefficients for the spherically symmetric PHOENIX models. The limb-darkening coefficients were computed by covering the transmission curves of Kepler, CoRoT, and Spitzer space missions, as well as the passbands of the Stromgren, Johnson-Cousins, Sloan, and 2MASS. These computations adopted the least-square method. In addition, we also calculated the linear and bi-parametric approximations by adopting the flux conservation method as an additional tool for estimating the theoretical error bars in the limb-darkening coefficients. Six laws were used to describe the specific intensity distribution: linear, quadratic, square root, logarithmic, exponential, and a more general one with 4 terms. The computations are presented for the solar chemical composition, with logg varying between 2.5 and 5.5 and effective temperatures between 1500K-4800K. The adopted Microturbulent velocity and the mixing-length parameters are 2.0km/s and 2.0, respectively. Model are for solar metallicity. (17 data files).

  12. The Effect of Manipulating Subject Mass on Lower Extremity Torque Patterns During Locomotion

    NASA Technical Reports Server (NTRS)

    DeWitt, John K.; Cromwell, Ronita L.; Hagan, R. Donald

    2007-01-01

    During locomotion, humans adapt their motor patterns to maintain coordination despite changing conditions (Reisman et al., 2005). Bernstein (1967) proposed that in addition to the present state of a given joint, other factors, including limb inertia and velocity, must be taken into account to allow proper motion to occur. During locomotion with added mass counterbalanced using vertical suspension to maintain body weight, vertical ground reaction forces (GRF's) increase during walking but decrease during running, suggesting that adaptation may be velocity-specific (De Witt et al., 2006). It is not known, however, how lower extremity joint torques adapt to changes in inertial forces. The purpose of this investigation was to examine the effects of increasing body mass while maintaining body weight upon lower-limb joint torque during walking and running. We hypothesized that adaptations in joint torque patterns would occur with the addition of body mass.

  13. Study of HD 169392A observed by CoRoT and HARPS

    NASA Astrophysics Data System (ADS)

    Mathur, S.; Bruntt, H.; Catala, C.; Benomar, O.; Davies, G. R.; García, R. A.; Salabert, D.; Ballot, J.; Mosser, B.; Régulo, C.; Chaplin, W. J.; Elsworth, Y.; Handberg, R.; Hekker, S.; Mantegazza, L.; Michel, E.; Poretti, E.; Rainer, M.; Roxburgh, I. W.; Samadi, R.; Stȩślicki, M.; Uytterhoeven, K.; Verner, G. A.; Auvergne, M.; Baglin, A.; Barceló Forteza, S.; Baudin, F.; Roca Cortés, T.

    2013-01-01

    Context. The results obtained by asteroseismology with data from space missions such as CoRoT and Kepler are providing new insights into stellar evolution. After five years of observations, CoRoT is continuing to provide high-quality data and we here present an analysis of the CoRoT observations of the double star HD 169392, complemented by ground-based spectroscopic observations. Aims: This work aims at characterising the fundamental parameters of the two stars, their chemical composition, the acoustic-mode global parameters including their individual frequencies, and their dynamics. Methods: We analysed HARPS observations of the two stars to derive their chemical compositions. Several methods were used and compared to determine the global properties of stars' acoustic modes and their individual frequencies from the photometric data of CoRoT. Results: The new spectroscopic observations and archival astrometric values suggest that HD 169392 is a weakly bound wide binary system. We obtained spectroscopic parameters for both components which suggest that they originate from the same interstellar cloud. However, only the signature of oscillation modes of HD 169392 A was measured; the signal-to-noise ratio of the modes in HD 169392B is too low to allow any confident detection. For HD 169392 A we were able to extract parameters of modes for ℓ = 0, 1, 2, and 3. The analysis of splittings and inclination angle gives two possible solutions: one with with splittings and inclination angles of 0.4-1.0 μHz and 20 - 40°, the other with 0.2-0.5 μHz and 55-86°. Modelling this star using the Asteroseismic Modeling Portal (AMP) gives a mass of 1.15 ± 0.01 M⊙, a radius of 1.88 ± 0.02 R⊙, and an age of 4.33 ± 0.12 Gyr. The uncertainties come from estimated errors on the observables but do not include uncertainties on the surface layer correction or the physics of stellar models. The CoRoT space mission, launched on December 27 2006, has been developed and is operated by

  14. Electric field driven torque in ATP synthase.

    PubMed

    Miller, John H; Rajapakshe, Kimal I; Infante, Hans L; Claycomb, James R

    2013-01-01

    FO-ATP synthase (FO) is a rotary motor that converts potential energy from ions, usually protons, moving from high- to low-potential sides of a membrane into torque and rotary motion. Here we propose a mechanism whereby electric fields emanating from the proton entry and exit channels act on asymmetric charge distributions in the c-ring, due to protonated and deprotonated sites, and drive it to rotate. The model predicts a scaling between time-averaged torque and proton motive force, which can be hindered by mutations that adversely affect the channels. The torque created by the c-ring of FO drives the γ-subunit to rotate within the ATP-producing complex (F1) overcoming, with the aid of thermal fluctuations, an opposing torque that rises and falls with angular position. Using the analogy with thermal Brownian motion of a particle in a tilted washboard potential, we compute ATP production rates vs. proton motive force. The latter shows a minimum, needed to drive ATP production, which scales inversely with the number of proton binding sites on the c-ring. PMID:24040370

  15. 14 CFR 25.361 - Engine torque.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... malfunction or structural failure (such as compressor jamming). (2) A limit engine torque load imposed by the... corresponding to takeoff power and propeller speed acting simultaneously with 75 percent of the limit loads from... propeller speed, acting simultaneously with the limit loads from flight condition A of § 25.333(b); and...

  16. 14 CFR 23.361 - Engine torque.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... compressor jamming). (2) A limit engine torque load imposed by the maximum acceleration of the engine. (c... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure Flight Loads § 23.361... 75 percent of the limit loads from flight condition A of § 23.333(d); (2) A limit engine...

  17. 14 CFR 23.361 - Engine torque.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... compressor jamming). (2) A limit engine torque load imposed by the maximum acceleration of the engine. (c... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure Flight Loads § 23.361... 75 percent of the limit loads from flight condition A of § 23.333(d); (2) A limit engine...

  18. 14 CFR 25.361 - Engine torque.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... malfunction or structural failure (such as compressor jamming). (2) A limit engine torque load imposed by the... corresponding to takeoff power and propeller speed acting simultaneously with 75 percent of the limit loads from... propeller speed, acting simultaneously with the limit loads from flight condition A of § 25.333(b); and...

  19. Nonambipolar Transport and Torque in Perturbed Equilibria

    NASA Astrophysics Data System (ADS)

    Logan, N. C.; Park, J.-K.; Wang, Z. R.; Berkery, J. W.; Kim, K.; Menard, J. E.

    2013-10-01

    A new Perturbed Equilibrium Nonambipolar Transport (PENT) code has been developed to calculate the neoclassical toroidal torque from radial current composed of both passing and trapped particles in perturbed equilibria. This presentation outlines the physics approach used in the development of the PENT code, with emphasis on the effects of retaining general aspect-ratio geometric effects. First, nonambipolar transport coefficients and corresponding neoclassical toroidal viscous (NTV) torque in perturbed equilibria are re-derived from the first order gyro-drift-kinetic equation in the ``combined-NTV'' PENT formalism. The equivalence of NTV torque and change in potential energy due to kinetic effects [J-K. Park, Phys. Plas., 2011] is then used to showcase computational challenges shared between PENT and stability codes MISK and MARS-K. Extensive comparisons to a reduced model, which makes numerous large aspect ratio approximations, are used throughout to emphasize geometry dependent physics such as pitch angle resonances. These applications make extensive use of the PENT code's native interfacing with the Ideal Perturbed Equilibrium Code (IPEC), and the combination of these codes is a key step towards an iterative solver for self-consistent perturbed equilibrium torque. Supported by US DOE contract #DE-AC02-09CH11466 and the DOE Office of Science Graduate Fellowship administered by the Oak Ridge Institute for Science & Education under contract #DE-AC05-06OR23100.

  20. Electric Field Driven Torque in ATP Synthase

    PubMed Central

    Miller, John H.; Rajapakshe, Kimal I.; Infante, Hans L.; Claycomb, James R.

    2013-01-01

    FO-ATP synthase (FO) is a rotary motor that converts potential energy from ions, usually protons, moving from high- to low-potential sides of a membrane into torque and rotary motion. Here we propose a mechanism whereby electric fields emanating from the proton entry and exit channels act on asymmetric charge distributions in the c-ring, due to protonated and deprotonated sites, and drive it to rotate. The model predicts a scaling between time-averaged torque and proton motive force, which can be hindered by mutations that adversely affect the channels. The torque created by the c-ring of FO drives the γ-subunit to rotate within the ATP-producing complex (F1) overcoming, with the aid of thermal fluctuations, an opposing torque that rises and falls with angular position. Using the analogy with thermal Brownian motion of a particle in a tilted washboard potential, we compute ATP production rates vs. proton motive force. The latter shows a minimum, needed to drive ATP production, which scales inversely with the number of proton binding sites on the c-ring. PMID:24040370

  1. Torque wrench allows readings from inaccessible locations

    NASA Technical Reports Server (NTRS)

    De Barnardo, M.

    1966-01-01

    Torque wrench with an adjustable drive shaft permits indicator to remain in view when used on sections of equipment with limited access. The shaft is capable of protruding from either side of the wrench head by means of spring loaded balls.

  2. A New Twist on Torque Labs

    ERIC Educational Resources Information Center

    Lane, W. Brian

    2014-01-01

    The traditional introductory-level meterstick-balancing lab assumes that students already know what torque is and that they readily identify it as a physical quantity of interest. We propose a modified version of this activity in which students qualitatively and quantitatively measure the amount of force required to keep the meterstick level. The…

  3. Torque-balanced vibrationless rotary coupling

    DOEpatents

    Miller, Donald M.

    1980-01-01

    This disclosure describes a torque-balanced vibrationless rotary coupling for transmitting rotary motion without unwanted vibration into the spindle of a machine tool. A drive member drives a driven member using flexible connecting loops which are connected tangentially and at diametrically opposite connecting points through a free floating ring.

  4. Electric field driven torque in ATP synthase.

    PubMed

    Miller, John H; Rajapakshe, Kimal I; Infante, Hans L; Claycomb, James R

    2013-01-01

    FO-ATP synthase (FO) is a rotary motor that converts potential energy from ions, usually protons, moving from high- to low-potential sides of a membrane into torque and rotary motion. Here we propose a mechanism whereby electric fields emanating from the proton entry and exit channels act on asymmetric charge distributions in the c-ring, due to protonated and deprotonated sites, and drive it to rotate. The model predicts a scaling between time-averaged torque and proton motive force, which can be hindered by mutations that adversely affect the channels. The torque created by the c-ring of FO drives the γ-subunit to rotate within the ATP-producing complex (F1) overcoming, with the aid of thermal fluctuations, an opposing torque that rises and falls with angular position. Using the analogy with thermal Brownian motion of a particle in a tilted washboard potential, we compute ATP production rates vs. proton motive force. The latter shows a minimum, needed to drive ATP production, which scales inversely with the number of proton binding sites on the c-ring.

  5. Direct and inverse spin-orbit torques

    NASA Astrophysics Data System (ADS)

    Freimuth, Frank; Blügel, Stefan; Mokrousov, Yuriy

    2015-08-01

    In collinear magnets lacking inversion symmetry, application of electric currents induces torques on the magnetization and conversely magnetization dynamics induces electric currents. The two effects, which both rely on spin-orbit interaction, are reciprocal to each other and denoted direct spin-orbit torque (SOT) and inverse spin-orbit torque (ISOT), respectively. We derive expressions for SOT and ISOT within the Kubo linear-response formalism. We show that expressions suitable for density-functional theory calculations can be derived either starting from a Kohn-Sham Hamiltonian with time-dependent exchange field or by expressing general susceptibilities in terms of the Kohn-Sham susceptibilities. For the case of magnetic bilayer systems we derive the general form of the ISOT current induced under ferromagnetic resonance. Using ab initio calculations within density-functional theory, we investigate SOT and ISOT in Co/Pt(111) magnetic bilayers. We determine the spatial distribution of spin and charge currents as well as torques in order to expose the mechanisms underlying SOT and ISOT and to highlight their reciprocity on the microscopic level. We find that the spin Hall effect is position dependent close to interfaces.

  6. 14 CFR 25.361 - Engine torque.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... corresponding to takeoff power and propeller speed acting simultaneously with 75 percent of the limit loads from... propeller speed, acting simultaneously with the limit loads from flight condition A of § 25.333(b); and (3...) of this section, a limit engine torque corresponding to takeoff power and propeller speed,...

  7. 14 CFR 23.361 - Engine torque.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...) A limit engine torque corresponding to takeoff power and propeller speed acting simultaneously with... corresponding to maximum continuous power and propeller speed acting simultaneously with the limit loads from... takeoff power and propeller speed, multiplied by a factor accounting for propeller control...

  8. 14 CFR 23.361 - Engine torque.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...) A limit engine torque corresponding to takeoff power and propeller speed acting simultaneously with... corresponding to maximum continuous power and propeller speed acting simultaneously with the limit loads from... takeoff power and propeller speed, multiplied by a factor accounting for propeller control...

  9. 14 CFR 25.361 - Engine torque.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... corresponding to takeoff power and propeller speed acting simultaneously with 75 percent of the limit loads from... propeller speed, acting simultaneously with the limit loads from flight condition A of § 25.333(b); and (3...) of this section, a limit engine torque corresponding to takeoff power and propeller speed,...

  10. 14 CFR 23.361 - Engine torque.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...) A limit engine torque corresponding to takeoff power and propeller speed acting simultaneously with... corresponding to maximum continuous power and propeller speed acting simultaneously with the limit loads from... takeoff power and propeller speed, multiplied by a factor accounting for propeller control...

  11. 14 CFR 25.361 - Engine torque.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... corresponding to takeoff power and propeller speed acting simultaneously with 75 percent of the limit loads from... propeller speed, acting simultaneously with the limit loads from flight condition A of § 25.333(b); and (3...) of this section, a limit engine torque corresponding to takeoff power and propeller speed,...

  12. Anatomy of a bearing torque problem

    NASA Technical Reports Server (NTRS)

    Phinney, Damon D.

    1987-01-01

    In the early 1970s, an antenna despin drive was developed for MBB solar science satellite HELIOS. A problem with high bearing drag torque that was encountered on the two flight models of this drive, after successful tests were completed on twelve bearings, an engineering model, and the qualification unit is discussed.

  13. Valgus torque in youth baseball pitchers: A biomechanical study.

    PubMed

    Sabick, Michelle B; Torry, Michael R; Lawton, Richard L; Hawkins, Richard J

    2004-01-01

    The purpose of this study was to determine the biomechanical and anthropometric factors contributing to elbow valgus torque during pitching. Video data of 14 youth pitchers throwing fastballs were used to calculate shoulder and elbow kinematics and kinetics. Peak elbow valgus torque averaged 18 Nm and occurred just before maximal shoulder external rotation. The magnitude of valgus torque was most closely correlated with the thrower's weight. When subject weight and height were controlled for, maximum shoulder abduction torque and maximum shoulder internal rotation torque were most strongly associated with elbow valgus torque, accounting for 85% of its variance (P <.001). When only kinematic variables were considered, maximum shoulder external rotation accounted for 33% of the variance in valgus torque. Given that the biomechanical variables correlated with peak valgus torque are not easily modifiable, limiting the number of innings pitched is likely the best way to reduce elbow injury in youth pitchers.

  14. The γ Doradus CoRoT target HD 49434. I. Results from the ground-based campaign

    NASA Astrophysics Data System (ADS)

    Uytterhoeven, K.; Mathias, P.; Poretti, E.; Rainer, M.; Martín-Ruiz, S.; Rodríguez, E.; Amado, P. J.; Le Contel, D.; Jankov, S.; Niemczura, E.; Pollard, K. R.; Brunsden, E.; Paparó, M.; Costa, V.; Valtier, J.-C.; Garrido, R.; Suárez, J. C.; Kilmartin, P. M.; Chapellier, E.; Rodríguez-López, C.; Marin, A. J.; Aceituno, F. J.; Casanova, V.; Rolland, A.; Olivares, I.

    2008-10-01

    Context: We present an extensive ground-based photometric and spectroscopic campaign of the γ Dor CoRoT target HD 49434. This campaign was a preparatory step of the CoRoT satellite observations, which occurred between October 2007 and March 2008. Aims: With satellite data, detection of low-degree pulsation modes only is achievable, and, as no filters are available, with poor identification. Ground-based data promise eventually to identify additional modes and provide extra input for the identification: spectroscopic data allows the detection of high-degree modes and an estimate of the azimuthal number m. We attempt to detect and identify as many pulsation modes as possible from the ground-based dataset of the γ Dor star HD 49434, and anticipate the CoRoT results. Methods: We searched for frequencies in the multi-colour variations, the pixel-to-pixel variations across the line profiles, and the moments variations in a large dataset, consisting of both multi-colour photometric and spectroscopic data from different observatories, using different frequency analysis methods. We performed a tentative mode identification of the spectroscopic frequencies using the Moment Method and the Intensity Period Search Method. We also completed an abundance analysis. Results: The frequency analysis clearly indicates the presence of four frequencies in the 0.2-1.7 d-1 interval, as well as six frequencies in the 5-12 d-1 domain. The low frequencies are typical of γ Dor variables, while the high frequencies are common to δ Sct pulsators. We propose that the frequency 2.666 d-1 is the rotational frequency. All modes, for which an identification was possible, appear to be high-degree modes (3 ≤ ell ≤ 8). We did not find evidence for a possible binary nature of the star HD 49434. The element abundances that we derived are consistent with values obtained in previous analyses. Conclusions: We classify the γ Dor star HD 49434 as a hybrid pulsator, which pulsates simultaneously in p

  15. Asteroseismology and mass loss in Be stars. Study with CoRoT

    NASA Astrophysics Data System (ADS)

    Diago, P. D.

    The general aim of this work is the study of Be stars with the CoRoT space mission. The mechanisms responsible of the production and dynamics of the circumstellar gas in Be stars are still not constrained. Observations of non-radial pulsation beating phenomena connected to outbursts point toward a relevance of pulsation, but this mechanism cannot be generalized. In this regard, the observation of classical Be stars with the high-precision CoRoT satellite is providing important keys to understand the physics of these objects and the nature of the Be phenomenon. In order to study the light variations of the selected stars we use photometric and spectroscopic observations. These observations allow us to extract frequencies, amplitudes and phases of these variations. As we will show, these light variations can be connected with pulsations on the stellar surface. For carrying out the frequency analysis we have developed a new code based on standard Fourier analysis. The point is that this code, called PASPER, allows the frequency analysis of large sets of light curves in an automatic mode. This Ph.D. thesis is arranged as follows: In the first three Chapters we describe the scientific framework of this project, giving a brief description on Asteroseismology, presenting the current status of Be stars, and describing the basics of the Fourier analysis and the rudiments of the time series analysis. At the early begin of this Ph.D. thesis, the CoRoT satellite was still on ground getting ready for the launch. In this context, we perform a search for short-period B and Be star variables in the low metallicity environment of the Magellanic Clouds. This study constitutes the Part I of this Ph.D. thesis. This Part has a double goal: i) to test the frequency analysis codes; and ii) to detect observationally beta Cephei and SPB-like B-type pulsators in low metallicity environments, actually not predicted by the pulsational theory and models. This constitutes the PartI. Part II is

  16. 40 CFR 90.306 - Dynamometer torque cell calibration.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Dynamometer torque cell calibration... Emission Test Equipment Provisions § 90.306 Dynamometer torque cell calibration. (a)(1) Any lever arm used...-cell or transfer standard may be used to verify the torque measurement system. (1) The master...

  17. 40 CFR 90.306 - Dynamometer torque cell calibration.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Dynamometer torque cell calibration... Emission Test Equipment Provisions § 90.306 Dynamometer torque cell calibration. (a)(1) Any lever arm used...-cell or transfer standard may be used to verify the torque measurement system. (1) The master...

  18. 40 CFR 90.306 - Dynamometer torque cell calibration.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Dynamometer torque cell calibration... Emission Test Equipment Provisions § 90.306 Dynamometer torque cell calibration. (a)(1) Any lever arm used...-cell or transfer standard may be used to verify the torque measurement system. (1) The master...

  19. 40 CFR 90.306 - Dynamometer torque cell calibration.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Dynamometer torque cell calibration... Emission Test Equipment Provisions § 90.306 Dynamometer torque cell calibration. (a)(1) Any lever arm used...-cell or transfer standard may be used to verify the torque measurement system. (1) The master...

  20. Lubricating additive for drilling muds

    SciTech Connect

    Gutierrez, A.; Brois, S. J.; Brownawell, D. W.; Walker, T. O.

    1985-01-01

    Aqueous drilling fluids containing a minor amount of an additive composition featuring oxazolines of C/sub 1/-C/sub 30/ alkylthioglycolic acid. Such fluids are especially useful where reduced torque drilling fluids are needed. Another embodiment of this invention relates to a method of drilling utilizing the above-described fluids.

  1. Performances improvements and torque ripple minimization for VSI fed induction machine with direct control torque.

    PubMed

    Abdelli, R; Rekioua, D; Rekioua, T

    2011-04-01

    This paper describes a torque ripple reduction technique with constant switching frequency for direct torque control (DTC) of an induction motor (IM). This method enables a minimum torque ripple control. In order to obtain a constant switching frequency and hence a torque ripple reduction, we propose a control technique for IM. It consists of controlling directly the electromagnetic torque by using a modulated hysteresis controller. The design methodology is based on space vector modulation (SVM) of electrical machines with digital vector control. MATLAB simulations supported with experimental study are used. The simulation and experimental results of this proposed algorithm show an adequate dynamic to IM; however, the research can be extended to include synchronous motors as well. The implementation of the proposed algorithm is described. It doesn't require any PI controller in the torque control loop. The hardware inverter is controlled digitally using a Texas Instruments TMS320F240 digital signal processor (DSP) with composed C codes for generating the required references. The results obtained from simulation and experiments confirmed the feasibility of the proposed strategy compared to the conventional one.

  2. An in-depth study of HD 174966 with CoRoT photometry and HARPS spectroscopy. Large separation as a new observable for δ Scuti stars

    NASA Astrophysics Data System (ADS)

    García Hernández, A.; Moya, A.; Michel, E.; Suárez, J. C.; Poretti, E.; Martín-Ruíz, S.; Amado, P. J.; Garrido, R.; Rodríguez, E.; Rainer, M.; Uytterhoeven, K.; Rodrigo, C.; Solano, E.; Rodón, J. R.; Mathias, P.; Rolland, A.; Auvergne, M.; Baglin, A.; Baudin, F.; Catala, C.; Samadi, R.

    2013-11-01

    Aims: The aim of this work was to use a multi-approach technique to derive the most accurate values possible of the physical parameters of the δ Sct star HD 174966, which was observed with the CoRoT satellite. In addition, we searched for a periodic pattern in the frequency spectra with the goal of using it to determine the mean density of the star. Methods: First, we extracted the frequency content from the CoRoT light curve. Then, we derived the physical parameters of HD 174966 and carried a mode identification out from the spectroscopic and photometric observations. We used this information to look for the models fulfilling all the conditions and discussed the inaccuracies of the method because of the rotation effects. In a final step, we searched for patterns in the frequency set using a Fourier transform, discussed its origin, and studied the possibility of using the periodicity to obtain information about the physical parameters of the star. Results: A total of 185 peaks were obtained from the Fourier analysis of the CoRoT light curve, all of which were reliable pulsating frequencies. From the spectroscopic observations, 18 oscillation modes were detected and identified, and the inclination angle (62.5°-17.5+7.5) and the rotational velocity of the star (142 km s-1) were estimated. From the multi-colour photometric observations, only three frequencies were detected that correspond to the main ones in the CoRoT light curve. We looked for periodicities within the 185 frequencies and found a quasiperiodic pattern Δν ~ 64 μHz. Using the inclination angle, the rotational velocity, and an Echelle diagram (showing a double comb outside the asymptotic regime), we concluded that the periodicity corresponds to a large separation structure. The quasiperiodic pattern allowed us to discriminate models from a grid. As a result, the value of the mean density is achieved with a 6% uncertainty. So, the Δν pattern could be used as a new observable for A-F type stars. The

  3. Uncertainty of knee joint muscle activity during knee joint torque exertion: the significance of controlling adjacent joint torque.

    PubMed

    Nozaki, Daichi; Nakazawa, Kimitaka; Akai, Masami

    2005-09-01

    In the single-joint torque exertion task, which has been widely used to control muscle activity, only the relevant joint torque is specified. However, the neglect of the neighboring joint could make the procedure unreliable, considering our previous result that even monoarticular muscle activity level is indefinite without specifying the adjacent joint torque. Here we examined the amount of hip joint torque generated with knee joint torque and its influence on the activity of the knee joint muscles. Twelve healthy subjects were requested to exert various levels of isometric knee joint torque. The knee and hip joint torques were obtained by using a custom-made device. Because no information about hip joint torque was provided to the subjects, the hip joint torque measured here was a secondary one associated with the task. The amount of hip joint torque varied among subjects, indicating that they adopted various strategies to achieve the task. In some subjects, there was a considerable internal variability in the hip joint torque. Such variability was not negligible, because the knee joint muscle activity level with respect to the knee joint torque, as quantified by surface electromyography (EMG), changed significantly when the subjects were requested to change the strategy. This change occurred in a very systematic manner: in the case of the knee extension, as the hip flexion torque was larger, the activity of mono- and biarticular knee extensors decreased and increased, respectively. These results indicate that the conventional single knee joint torque exertion has the drawback that the intersubject and/or intertrial variability is inevitable in the relative contribution among mono- and biarticular muscles because of the uncertainty of the hip joint torque. We discuss that the viewpoint that both joint torques need to be considered will bring insights into various controversial problems such as the shape of the EMG-force relationship, neural factors that help

  4. A new model to compute the desired steering torque for steer-by-wire vehicles and driving simulators

    NASA Astrophysics Data System (ADS)

    Fankem, Steve; Müller, Steffen

    2014-05-01

    This paper deals with the control of the hand wheel actuator in steer-by-wire (SbW) vehicles and driving simulators (DSs). A novel model for the computation of the desired steering torque is presented. The introduced steering torque computation does not only aim to generate a realistic steering feel, which means that the driver should not miss the basic steering functionality of a modern conventional steering system such as an electric power steering (EPS) or hydraulic power steering (HPS), and this in every driving situation. In addition, the modular structure of the steering torque computation combined with suitably selected tuning parameters has the objective to offer a high degree of customisability of the steering feel and thus to provide each driver with his preferred steering feel in a very intuitive manner. The task and the tuning of each module are firstly described. Then, the steering torque computation is parameterised such that the steering feel of a series EPS system is reproduced. For this purpose, experiments are conducted in a hardware-in-the-loop environment where a test EPS is mounted on a steering test bench coupled with a vehicle simulator and parameter identification techniques are applied. Subsequently, how appropriate the steering torque computation mimics the test EPS system is objectively evaluated with respect to criteria concerning the steering torque level and gradient, the feedback behaviour and the steering return ability. Finally, the intuitive tuning of the modular steering torque computation is demonstrated for deriving a sportier steering feel configuration.

  5. Close-in planet migration due to magnetic torques

    NASA Astrophysics Data System (ADS)

    Strugarek, Antoine; Brun, Allan Sacha; Matt, Sean; Réville, Victor

    2015-08-01

    The diversity of masses, sizes and orbits of known exoplanets has prompted recent efforts in the scientific community to explore the broad range of interactions that can exist between planets and their host stars. In addition to tidal interactions, planets orbiting inside the stellar wind Alfv ´en radius can magnetically interact with their host. These interactions could lead to an angular momentum transfer between the planet and its host, resulting in a substantial planetary migration and participating in the dynamical (in)stability of the system. Among the star-planet interaction (SPI) models that have been developed, magnetohydrodynamic (MHD) simulations combine state of the art numerical models of cool star magnetospheres with simplified models of planets. The advantage of these global, dynamical models is the ability to assess the effects of SPI in a self-consistent way, by modelling the full interaction channel from the planetary magnetosphere down to the lower stellar corona.We will present our study of global magnetic SPI using the PLUTO code. We first give an overview of different types of interactions, depending on the stellar wind and orbital properties. Based on our previous exploratory 2D axisymmetric study, we develop our magnetic interaction model in 3D to tackle the full geometry of the star-wind- planet connection. We study the formation of Aflv ´en wings and parametrize the key physical ingredients (magnetic field strength and topology, orbital distance, stellar wind mass and angular momentum loss rates) controlling the magnetic torques which lead to planet migration. These torques are shown to operate on time-scales comparable to tidal torques for sufficiently compact systems and favorable magnetic topologies.

  6. Study of the geoeffectiveness of coronal mass ejections, corotating interaction regions and their associated structures observed during Solar Cycle 23

    NASA Astrophysics Data System (ADS)

    Badruddin, A.; Falak, Z.

    2016-08-01

    The interplanetary coronal mass ejections (ICMEs) and the corotating interaction regions (CIRs) are the two most important structures of the interplanetary medium affecting the Earth and the near-Earth space environment. We study the solar wind-magnetosphere coupling during the passage of ICMEs and CIRs, in the Solar Cycle 23 (Jan. 1995-Dec. 2009), and their relative geoeffectiveness. We utilize the timings of different features of these structures, their arrival and duration. As geomagnetic parameter, we utilize high time resolution data of Dst and AE indices. In addition to these geomagnetic indices, we utilize the simultaneous and similar time resolution data of interplanetary plasma and field, namely, solar wind velocity, interplanetary magnetic field, its north-south component and dawn-dusk electric field. We apply the method of superposed epoch analysis. Utilizing the properties of various structures during the passage of ICMEs and CIRs, and variations observed in plasma and field parameters during their passage along with the simultaneous changes observed in geomagnetic parameters, we identify the interplanetary conditions, plasma/field parameters and their relative importance in solar wind-magnetosphere coupling. Geospace consequences of ICMEs and CIRs, and the implications of these results for solar wind-magnetosphere coupling are discussed.

  7. A Two Fiber Bragg Gratings Sensing System to Monitor the Torque of Rotating Shaft.

    PubMed

    Wang, Yongjiao; Liang, Lei; Yuan, Yinquan; Xu, Gang; Liu, Fang

    2016-01-01

    By fixing two FBGs on the surface of a rotating shaft along the direction of ± 45° and using dynamic wavelength demodulation technology, we propose an optical fiber sensing system to monitor the driving torque and torsion angle of the rotating shaft. In theory, the dependence relation of the dynamic difference of central wavelengths on the torque and torsion angle of the rotating shaft has been deduced. To verify an optical fiber sensing system, a series of sensing experiments have been completed and the measured data are approximately consistent with the theoretical analysis. The difference of two central wavelengths can be expressed as the sum of two parts: a "DC" part and a harmonic "AC" part. The driving torque or torsion angle is linear with the "DC" part of the difference of two central wavelengths, the harmonic "AC" part, meaning the torsion angle vibration, illustrates that periodic vibration torque may be caused by inhomogeneous centrifugal forces or inhomogeneous additional torques produced by the driving system and the load. PMID:26805843

  8. Optical interaction between small plasmonic nanowires: a perspective from induced forces and torques

    NASA Astrophysics Data System (ADS)

    Ekeroth, Ricardo M. Abraham

    2016-08-01

    This paper addresses a new numerical study of the near electromagnetic coupling between two small, metallic nanowires under plane-wave illumination. The forces and torques induced give a different point of view of the interaction. The analysis of these near-field, mechanical observables is based entirely on the plasmon hybridization model, with the help of an adequate correlation with far fields. Although several studies of the opto-mechanical inductions have been done, unexpected features of the movement are obtained. ‘Coordinated’ spin for the wires are found, in addition to binding or repulsion forces between the wires and scattering forces. For heterodimers, also orbital torques are obtained. The binding and rotation of the nanowires as well as orbital torques are strongly dependent on the plasmonic excitations of the system. They identify uniquely the surface plasmons. In particular, dark modes can be optically detected without using evanescent fields. The optical forces and torques are calculated exactly by Maxwell stress tensor. ‘Realistic’ infinite nanowires of silver and gold are simulated by a size correction in bulk dielectric function. Thus, the importance of this correction on the mechanical results is also studied. The results can contribute to the design of devices for real observation/detection of surface plasmons. The spectra of forces, and specially of torques, show more resolved resonances because overlapping effects are not as present as in far-field calculations. The spinning of wires found and the analysis made could open new directions of studies and applications of dimers.

  9. Effect of rotator cuff exercise on humeral rotation torque in healthy individuals.

    PubMed

    Moncrief, Scott A; Lau, Jeffery D; Gale, Judith R; Scott, Samuel A

    2002-05-01

    Conservative management of rotator cuff pathology often involves certain therapeutic exercises. Although a major goal of these exercises is to increase strength of the rotator cuff, little empirical evidence supports this assertion. In this study, 34 nonpathologic young adults were pretested using a LIDO Multijoint II isokinetic device for average and peak torque generated during internal and external rotation. Subjects were arbitrarily assigned to a right-arm- or left-arm-trained group, exercised for 4 weeks, and then posttested for changes in humeral rotation torque. Moderate but significant increases in torque (8-10%) as well as in total work done were observed in both groups, only in the trained arm. Subjects who trained the nondominant (left) arm experienced gains similar to those who trained the right arm. Gains were significant in the case of both internal and external rotation (also average as well as peak torque), with men and women experiencing the same relative increases. These data, in addition to supporting the use of selected exercises to increase humeral rotation torque in a healthy population, offer a potential model for the rehabilitation of patients with rotator cuff injury. PMID:11991780

  10. Elastic and hydrodynamic torques on a colloidal disk within a nematic liquid crystal

    NASA Astrophysics Data System (ADS)

    Rovner, Joel B.; Borgnia, Dan S.; Reich, Daniel H.; Leheny, Robert L.

    2012-10-01

    The orientationally dependent elastic energy and hydrodynamic behavior of colloidal disks with homeotropic surface anchoring suspended in the nematic liquid crystal 4-cyano-4'-pentylbiphenyl (5CB) have been investigated. In the absence of external torques, the disks align with the normal of the disk face â parallel to the nematic director n̂. When a magnetic field is applied, the disks rotate â by an angle θ so that the magnetic torque and the elastic torque caused by distortion of the nematic director field are balanced. Over a broad range of angles, the elastic torque increases linearly with θ in quantitative agreement with a theoretical prediction based on an electrostatic analogy. When the disks are rotated to angles θ>(π)/(2), the resulting large elastic distortion makes the disk orientation unstable, and the director undergoes a topological transition in which θπ-θ. In the transition, a defect loop is shed from the disk surface, and the disks spin so that â sweeps through π radians as the loop collapses back onto the disk. Additional measurements of the angular relaxation of disks to θ=0 following removal of the external torque show a quasi-exponential time dependence from which an effective drag viscosity for the nematic can be extracted. The scaling of the angular time dependence with disk radius and observations of disks rotating about â indicate that the disk motion affects the director field at surprisingly modest Ericksen numbers.

  11. A Two Fiber Bragg Gratings Sensing System to Monitor the Torque of Rotating Shaft

    PubMed Central

    Wang, Yongjiao; Liang, Lei; Yuan, Yinquan; Xu, Gang; Liu, Fang

    2016-01-01

    By fixing two FBGs on the surface of a rotating shaft along the direction of ±45° and using dynamic wavelength demodulation technology, we propose an optical fiber sensing system to monitor the driving torque and torsion angle of the rotating shaft. In theory, the dependence relation of the dynamic difference of central wavelengths on the torque and torsion angle of the rotating shaft has been deduced. To verify an optical fiber sensing system, a series of sensing experiments have been completed and the measured data are approximately consistent with the theoretical analysis. The difference of two central wavelengths can be expressed as the sum of two parts: a “DC” part and a harmonic “AC” part. The driving torque or torsion angle is linear with the “DC” part of the difference of two central wavelengths, the harmonic “AC” part, meaning the torsion angle vibration, illustrates that periodic vibration torque may be caused by inhomogeneous centrifugal forces or inhomogeneous additional torques produced by the driving system and the load. PMID:26805843

  12. Amplitude-phase coupling in a spin-torque nano-oscillator

    NASA Astrophysics Data System (ADS)

    Kudo, Kiwamu; Nagasawa, Tazumi; Sato, Rie; Mizushima, Koichi

    2009-04-01

    The spin-torque nano-oscillator in the presence of thermal fluctuation is described by the normal form of the Hopf bifurcation with an additive white noise. By the application of the reduction method, the amplitude-phase coupling factor, which has a significant effect on the power spectrum of the spin-torque nano-oscillator, is calculated from the Landau-Lifshitz-Gilbert-Slonczewski equation with the nonlinear Gilbert damping. The amplitude-phase coupling factor exhibits a large variation depending on an in-plane anisotropy under the practical external fields.

  13. Students' difficulties in interpreting the torque vector in a physical situation

    NASA Astrophysics Data System (ADS)

    Barniol, Pablo; Zavala, Genaro; Hinojosa, Carlos

    2013-01-01

    In this article we investigate students' difficulties in interpreting the torque vector in a physical situation. To identify these difficulties, we carried out task-based interviews with undergraduate physics majors completing a junior level course in mechanics. In the task, we presented a drawing of a beam that is initially at equilibrium over a fulcrum. Later, a weight is hung from the left side. We detected an alternative conception in which students thought that the left side of the beam and the weight would have additional motion in the direction of the torque vector. To quantify students having this alternative conception, we designed and administered a multiple-choice question to undergraduate physics majors completing a sophomore-level modern physics course. We found that 18% of the students had this conception. Based on these results, we present some suggestions for instruction of the torque vector concept.

  14. Hysteresis compensation of photoluminescence in ZnS:Cu for noncontact shaft torque sensing.

    PubMed

    Cho, Min-Young; Kim, Ji-Sik; Kim, Gi-Woo

    2016-03-01

    This paper presents a preliminary investigation of loading rate-dependent hysteresis of photoluminescence (PL) by phosphorescence quenching of copper-doped zinc sulfide (ZnS:Cu) microparticles in response to dynamic torsional loading. Precision sinusoidal torque waveforms in the frequency range of 0.5-3 Hz are used to identify the loading rate-dependent (i.e., frequency-dependent) nonlinear hysteresis phenomenon. The potential of the application of PL is demonstrated by successfully measuring the sinusoidal torque applied to a rotational shaft by evaluating the loading rate-dependent PL intensity signature using a photomultiplier tube. In addition, the potential of noncontact shaft torque sensing is demonstrated successfully by the simple compensation derived from ad hoc heuristic characterization. PMID:26974628

  15. Large voltage-induced modification of spin-orbit torques in Pt/Co/GdOx

    SciTech Connect

    Emori, Satoru Bauer, Uwe; Woo, Seonghoon; Beach, Geoffrey S. D.

    2014-12-01

    We report on large modifications of current-induced spin-orbit torques in a gated Pt/Co/Gd-oxide microstrip due to voltage-driven O{sup 2−} migration. The Slonczewski-like and field-like torques are quantified using a low-frequency harmonic technique based on the polar magneto-optical Kerr effect. Voltage-induced oxidation of Co enhances the Slonczewski-like torque by as much as an order of magnitude and simultaneously reduces the anisotropy energy barrier by a factor of ∼5. Such magneto-ionic tuning of interfacial spin-orbit effects may significantly enhance the efficiency of magnetization switching and provide additional degrees of freedom in spintronic devices.

  16. Alignment of Dust by Radiative Torque: Recent Developments

    NASA Astrophysics Data System (ADS)

    Lazarian, A.; Hoang, T.

    2011-11-01

    Alignment of dust by radiative torques (RATs) has proven to be the most promising mechanism to explain alignment in various astrophysical environments, from comet atmospheres to circumstellar accretion disks, molecular clouds, and diffuse interstellar gas. Recent years have been marked by intensive attempts to provide proper theoretical treatment of the alignment process. We discuss some of the major advances, which include, first of all, formulating of the analytical model of RATs. This model was shown to reproduce well the torques acting on actual irregular dust grains and allowed studies of the parameter space for which the alignment happens with long axes perpendicular and parallel to the magnetic field. Such a study resulted in an important conclusion that, without any paramagnetic relaxation, the RAT alignment always happens for interstellar grains with long axes perpendicular to the magnetic field. Incidentally, this conclusion is not true for the alignment of large (i.e. a > 10-4 cm) grains that are present, e.g. in accretion disks, as these grains can demonstrate both the alignment with long axes parallel and perpendicular to the magnetic field, although the alignment with long grain axes perpendicular to the magnetic field is preferential in many cases, which can also be identified with the analytical model. Additional recent advances include the description of effects of gaseous bombardment and pinwheel torques on grains aligned by RATs. Very counterintuitively, the gaseous bombardment was shown in some cases to increase the degree of alignment by knocking out grains from the positions of imperfect alignment when the grains rotate slowly to more stable positions of perfect alignment where grains rotate fast. In terms of pinwheel torques, important revisions have been made in the Lazarian & Draine model of grain flipping and thermal trapping. Those, however, do not change the major conclusion that very small grains (i.e. a < 3× 10-6 cm) should be

  17. Significance of the Pars Interarticularis in the Cortical Bone Trajectory Screw Technique: An In Vivo Insertional Torque Study

    PubMed Central

    Iwatsuki, Koichi; Ohnishi, Yu-Ichiro; Ohkawa, Toshika; Yoshimine, Toshiki

    2016-01-01

    Study Design Retrospective study. Purpose Cortical bone trajectory (CBT), a more medial-to-lateral and shorter path than the traditional one for spinal fusion, is thought to be effective for severely degenerated vertebrae because screws are primarily stabilized at the posterior elements. We evaluated the efficacy of this approach through in vivo insertional torque measurement. Overview of Literature There has been only one prior in vivo study on CBT insertional torque. Methods Between January 2013 and April 2014, a total of 22 patients underwent posterior lumbar fusion using the CBT technique. The maximum insertional torque, which covers the radial strength needed for insertion, was measured for 113 screws, 8 of which were inserted for L5 spondylolysis. The insertional torque for cases with (n=8) and without (n=31) spondylolysis of L5 were compared using one-way analysis of variance (ANOVA). To evaluate vertebral degeneration, we classified 53 vertebrae without spondylolysis by lumbar radiography using semiquantitative methods; the insertional torque for the 105 screws used was compared on the basis of this classification. Additionally, differences in insertional torque among cases grouped by age, sex, and lumbar level were evaluated for these 105 screws using ANOVA and the Tukey test. Results The mean insertional torque was significantly lower for patients with spondylolysis than for those without spondylolysis (4.25 vs. 8.24 in-lb). There were no statistical differences in insertional torque according to vertebral grading or level. The only significant difference in insertional torque between age and sex groups was in men <75 years and women ≥75 years (10 vs. 5.5 in-lb). Conclusions Although CBT should be used with great caution in patient with lysis who are ≥75 years, it is well suited for dealing with severely degenerated vertebrae because the pars interarticularis plays a very important role in the implementation of this technique. PMID:27790318

  18. Torque generated by the flagellar motor of Escherichia coli.

    PubMed Central

    Berg, H C; Turner, L

    1993-01-01

    Cells of the bacterium Escherichia coli were tethered and spun in a high-frequency rotating electric field at a series of discrete field strengths. This was done first at low field strengths, then at field strengths generating speeds high enough to disrupt motor function, and finally at low field strengths. Comparison of the initial and final speed versus applied-torque plots yielded relative motor torque. For backward rotation, motor torque rose steeply at speeds close to zero, peaking, on average, at about 2.2 times the stall torque. For forward rotation, motor torque remained approximately constant up to speeds of about 60% of the zero-torque speed. Then the torque dropped linearly with speed, crossed zero, and reached a minimum, on average, at about -1.7 times the stall torque. The zero-torque speed increased with temperature (about 90 Hz at 11 degrees C, 140 Hz at 16 degrees C, and 290 Hz at 23 degrees C), while other parameters remained approximately constant. Sometimes the motor slipped at either extreme (delivered constant torque over a range of speeds), but eventually it broke. Similar results were obtained whether motors broke catastrophically (suddenly and completely) or progressively or were de-energized by brief treatment with an uncoupler. These results are consistent with a tightly coupled ratchet mechanism, provided that elastic deformation of force-generating elements is limited by a stop and that mechanical components yield at high applied torques. PMID:8298044

  19. CoRoT-7b: Convection in a Tidally Locked Planet

    NASA Astrophysics Data System (ADS)

    Noack, Lena; Stamenkovic, Vlada; Wagner, Frank W.; Sohl, Frank; Breuer, Doris

    2010-05-01

    The number of terrestrial extrasolar planets found in the past few years is increasing rapidly. Some have masses ranging from 2 to 10 Earth masses, and the habitability of these planets is widely discussed in the planetary community. Due to observational limitations we will mostly be able to observe planets that are very close to its host star, resulting in a potentially tidally locked orbit. Our goal is to investigate if such planets can be habitable at all. But to do so, we first have to understand the convection behaviour of such planets. In this work we model the mantle convection of the recently discovered exoplanet CoRoT-7b [1], which is a planet believed to be tidally locked. The extreme intense insolation in the vicinity of its host star heats the day-side of CoRoT-7b, leading to surface temperatures about 2000 Kelvin higher than on the night-side [1]. CoRoT-7b is about 5 times more massive than the Earth and predominantly composed of dry silicate rock similar to Earth's Moon. A central iron core, if present, would be relatively small [2] with a core mass fraction of no more than 15 wt%. The mantle convection is modelled in a spherical shell [3] using a temperature- and pressure-dependent viscosity. We use a radioactive heat source density similar to present Earth. Coriolis forces are neglected and we assume that CoRoT-7b has no atmosphere. The results show that the lower mantle above the core-mantle boundary is in a more sluggish convection regime as a consequence of the viscosity increase with pressure. Depending on the strength of the viscosity increase, even a so-called low-lid [4] can form and conductive heat transport dominates from the core to the upper part of the mantle. The thermal state of such a deeply situated, conductive lower mantle of CoRoT-7b is not much influenced by the strongly laterally varying surface temperature. However, the temperatures of the upper convecting mantle are found to strongly vary from one side of the planet to the

  20. Manipulating quantum information with spin torque

    PubMed Central

    Sutton, Brian; Datta, Supriyo

    2015-01-01

    The use of spin torque as a substitute for magnetic fields is now well established for classical operations like the switching of a nanomagnet. What we are describing here could be viewed as an application of spin torque like effects to quantum processes involving single qubit rotations as well as two qubit entanglement. A key ingredient of this scheme is the use of a large number of itinerant electrons whose cumulative effect is to produce the desired qubit operations on static spins. Each interaction involves entanglement and collapse of wavefunctions so that the operation is only approximately unitary. However, we show that the non-unitary component of the operations can be kept below tolerable limits with proper design. As a capstone example, we present the implementation of a complete CNOT gate using the proposed spin potential based architecture, and show that the fidelity under ideal conditions can be made acceptably close to one. PMID:26648524

  1. Torque Transmission Device at Zero Leakage

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.; Mullen, R. L.

    2005-01-01

    In a few critical applications, mechanical transmission of power by rotation at low speed is required without leakage at an interface. Herein we examine a device that enables torque to be transmitted across a sealed environmental barrier. The barrier represents the restraint membrane through which the torque is transmitted. The power is transferred through elastic deformation of a circular tube into an elliptical cross-section. Rotation of the principle axis of the ellipse at one end results in a commensurate rotation of an elliptical cross section at the other end of the tube. This transfer requires no rigid body rotation of the tube allowing a membrane to seal one end from the other. Both computational and experimental models of the device are presented.

  2. Mode coupling in spin torque oscillators

    NASA Astrophysics Data System (ADS)

    Zhang, Steven S.-L.; Zhou, Yan; Li, Dong; Heinonen, Olle

    2016-09-01

    A number of recent experimental works have shown that the dynamics of a single spin torque oscillator can exhibit complex behavior that stems from interactions between two or more modes of the oscillator, such as observed mode-hopping or mode coexistence. There has been some initial work indicating how the theory for a single-mode (macro-spin) spin torque oscillator should be generalized to include several modes and the interactions between them. In the present work, we rigorously derive such a theory starting with the Landau-Lifshitz-Gilbert equation for magnetization dynamics by expanding up to third-order terms in deviation from equilibrium. Our results show how a linear mode coupling, which is necessary for observed mode-hopping to occur, arises through coupling to a magnon bath. The acquired temperature dependence of this coupling implies that the manifold of orbits and fixed points may shift with temperature.

  3. Manipulation of spin transfer torque using light

    NASA Astrophysics Data System (ADS)

    Rontani, Massimo; Vendelbjerg, Karsten; Sham, Lu

    We show that the spin transfer torque induced by a spin-polarized current on a nanomagnet as the current flows through a semiconductor-nanomagnet-semiconductor junction is externally controlled by shining the junction off-resonantly with a strong laser beam. The excitonic coherence driven by the laser dresses the virtual electron-hole pairs coupling conduction and valence bands and inducing an evanescent state in the proximity of the nanomagnet. The Fano-like quantum interference between this localized state and the continuum spectrum is different in the two spin channels and hence it dramatically alters the spin transport, leading to the coherent control of the spin transfer torque. This work is supported by EU-FP7 Marie Curie Initial Training Network INDEX.

  4. Six component robotic force-torque sensor

    NASA Technical Reports Server (NTRS)

    Grahn, Allen R.; Hutchings, Brad L.; Johnston, David R.; Parsons, David C.; Wyatt, Roland F.

    1987-01-01

    The results of a two-phase contract studying the feasibility of a miniaturized six component force-torque sensor and development of a working laboratory system were described. The principle of operation is based upon using ultrasonic pulse-echo ranging to determine the position of ultrasonic reflectors attached to a metal or ceramic cover plate. Because of the small size of the sensor, this technology may have application in robotics, to sense forces and torques at the finger tip of a robotic end effector. Descriptions are included of laboratory experiments evaluating materials and techniques for sensor fabrication and of the development of support electronics for data acquisition, computer interface, and operator display.

  5. An ironless armature brushless torque motor

    NASA Technical Reports Server (NTRS)

    Studer, P. A.

    1973-01-01

    A high torque motor with improved servo mechanism is reported. Armature windings are cast into an epoxy cylinder and armature conductors are integrally cast with an aluminum mounting ring which provides thermal conductance directly into the structure. This configuration eliminates magnetic hysteresis because there is no relative motion between the rotating magnetic field and any stationary iron. The absence of destabilization forces provides a fast electrical response compared with a typical torquer of conventional construction.

  6. COROT-high-precision stellar photometry on a low Earth orbit: solutions to minimize environmental perturbations

    NASA Astrophysics Data System (ADS)

    Auvergne, Michel; Boisnard, Laurent; Buey, Jean-Tristan M.; Epstein, Gerard; Hustaix, Herve; Jouret, Martine; Levacher, Patrick; Berrivin, Stephane; Baglin, Annie

    2003-02-01

    The COROT small satellite project is a space mission dedicated to stellar seismology and search for telluric extra-solar planets. For the two programs a very high photometric precision is needed. The COROT seismology program will measure periodic variations with amplitude of 2.10-6 of the photon flux emitted by bright stars. COROT will also be able to detect the presence of exoplanets when they pass between the satellite and their parent star. Modifying both the integration time and the focus conditions, it allows to detect photons flux variations about 7.10-4 in one hour integration, compatible with an occultation detection on a very large number of stars (magnitude between 12 and 15.5). Between 10 and 40 telluric planets in the "habitable zone" and several hundreds of hot Jupiters should be detected depending on hypotheses about planets existence. To reach the required performances a stringent instrument stability is necessary. The satellite Preliminary Design Review will be held in November 2002 while the instrument is already in development phase for a delivery of the flight model in 2004. The launch is scheduled late 2005, by the first SOYUZ launcher to fly from the Guyana Space Center. The project activities are currently focused on the instrument and system engineering. Straylight rejection, pointing, thermal stability are the main critical points of the mission, on a LEO at 826 kms, for which cost-effective compromises have been found to 1mit their effects. This paper recalls the scientific program s, the main characteristics of the mission, describes the impact of the three main perturbators on the photometric precision and the technical solutions which reduce their contribution at an acceptable level.

  7. Development of corotational formulated FEM for application to 30m class large deployable reflector

    NASA Astrophysics Data System (ADS)

    Ozawa, Satoru; Fujiwara, Yuuichi; Tsujihata, Akio

    2010-06-01

    JAXA, Japan Aerospace Exploration Agency, is now developing a corotational formulated finite element analysis method and its software "Origami/ETS" for the development of 30m class large deployable reflectors. For the reason that the deployable reflector is composed of beams, cables and mesh, this analysis method is generalized for finite elements with multiple nodes, which are commonly used in linear finite element analyses. The large displacement and rotation are taken into account by the corotational formulation. The tangent stiffness matrix for finite elements with multiple nodes is obtained as follows; the geometric stiffness matrix of two node elements is derived by taking variation of the element's corotational matrix from the virtual work of finite elements with large displacement; similarly the geometric stiffness matrix for three node elements is derived; as the extension of two and three node element theories, the geometric stiffness matrix for multiple node elements is derived; with the geometric stiffness matrix for multiple node elements, the tangent stiffness matrix is obtained. The analysis method is applied for the deployment analysis and static structural analysis of the 30m class large deployable reflector. In the deployment analysis, it is confirmed that this method stably analyzes the deployment motion from the deployment configuration to the stowed configuration of the reflector. In the static analysis, it is confirmed that the mesh structure is analyzed successfully. The 30m class large deployable reflector is now still being developed and is about to undergo several tests with its prototypes. This analysis method will be used in the tests and verifications of the reflector.

  8. A new eclipsing binary system with a pulsating component detected by CoRoT

    NASA Astrophysics Data System (ADS)

    Sokolovsky, K.; Maceroni, C.; Hareter, M.; Damiani, C.; Balaguer-Núñez, L.; Ribas, I.

    2010-06-01

    We report the discovery of CoRoT 102980178 (α = 06h 50m12.10s , δ = -02°41' 21.8'', J2000) an Algol-type eclipsing binary system with a pulsating component (oEA). It was identified using a publicly available 55 day long monochromatic lightcurve from the CoRoT initial run dataset (exoplanet field). Eleven consecutive 1.26m deep total primary and the equal number of 0.25m deep secondary eclipses (at phase 0.50) were observed. The following light elements for the primary eclipse were derived: HJDMinI = 2454139.0680 + 5.0548d × E. The lightcurve modeling leads to a semidetached configuration with the photometric mass ratio q = 0.2 and orbital inclination i = 85°. The out-of-eclipse lightcurve shows ellipsoidal variability and positive O'Connell effect as well as clear 0.01m pulsations with the dominating frequency of 2.75 c/d. The pulsations disappear during the primary eclipses, which indicates the primary (more massive) component to be the pulsating star. Careful frequency analysis reveals the second independent pulsation frequency of 0.21 c/d and numerous combinations of these frequencies with the binary orbital frequency and its harmonics. On the basis of the CoRoT lightcurve and ground based multicolor photometry, we favor classification of the pulsating component as a γ Doradus type variable, however, classification as an SPB star cannot be excluded.

  9. MOST detects corotating bright spots on the mid-O-type giant ξ Persei

    NASA Astrophysics Data System (ADS)

    Ramiaramanantsoa, Tahina; Moffat, Anthony F. J.; Chené, André-Nicolas; Richardson, Noel D.; Henrichs, Huib F.; Desforges, Sébastien; Antoci, Victoria; Rowe, Jason F.; Matthews, Jaymie M.; Kuschnig, Rainer; Weiss, Werner W.; Sasselov, Dimitar; Rucinski, Slavek M.; Guenther, David B.

    2014-06-01

    We have used the MOST (Microvariability and Oscillations of STars) microsatellite to obtain four weeks of contiguous high-precision broad-band visual photometry of the O7.5III(n)((f)) star ξ Persei in 2011 November. This star is well known from previous work to show prominent DACs (discrete absorption components) on time-scales of about 2 d from UV spectroscopy and non-radial pulsation with one (l = 3) p-mode oscillation with a period of 3.5 h from optical spectroscopy. Our MOST-orbit (101.4 min) binned photometry fails to reveal any periodic light variations above the 0.1 mmag 3σ noise level for periods of a few hours, while several prominent Fourier peaks emerge at the 1 mmag level in the two-day period range. These longer period variations are unlikely due to pulsations, including gravity modes. From our simulations based upon a simple spot model, we deduce that we are seeing the photometric modulation of several corotating bright spots on the stellar surface. In our model, the starting times (random) and lifetimes (up to several rotations) vary from one spot to another yet all spots rotate at the same period of 4.18 d, the best-estimated rotation period of the star. This is the first convincing reported case of corotating bright spots on an O star, with important implications for drivers of the DACs (resulting from corotating interaction regions) with possible bright-spot generation via a breakout at the surface of a global magnetic field generated by a subsurface convection zone.

  10. Comparison of regression models for estimation of isometric wrist joint torques using surface electromyography

    PubMed Central

    2011-01-01

    Background Several regression models have been proposed for estimation of isometric joint torque using surface electromyography (SEMG) signals. Common issues related to torque estimation models are degradation of model accuracy with passage of time, electrode displacement, and alteration of limb posture. This work compares the performance of the most commonly used regression models under these circumstances, in order to assist researchers with identifying the most appropriate model for a specific biomedical application. Methods Eleven healthy volunteers participated in this study. A custom-built rig, equipped with a torque sensor, was used to measure isometric torque as each volunteer flexed and extended his wrist. SEMG signals from eight forearm muscles, in addition to wrist joint torque data were gathered during the experiment. Additional data were gathered one hour and twenty-four hours following the completion of the first data gathering session, for the purpose of evaluating the effects of passage of time and electrode displacement on accuracy of models. Acquired SEMG signals were filtered, rectified, normalized and then fed to models for training. Results It was shown that mean adjusted coefficient of determination (Ra2) values decrease between 20%-35% for different models after one hour while altering arm posture decreased mean Ra2 values between 64% to 74% for different models. Conclusions Model estimation accuracy drops significantly with passage of time, electrode displacement, and alteration of limb posture. Therefore model retraining is crucial for preserving estimation accuracy. Data resampling can significantly reduce model training time without losing estimation accuracy. Among the models compared, ordinary least squares linear regression model (OLS) was shown to have high isometric torque estimation accuracy combined with very short training times. PMID:21943179

  11. Dynamics of a split torque helicopter transmission

    NASA Technical Reports Server (NTRS)

    Rashidi, Majid; Krantz, Timothy

    1992-01-01

    A high reduction ratio split torque gear train has been proposed as an alternative to a planetary configuration for the final stage of a helicopter transmission. A split torque design allows a high ratio of power-to-weight for the transmission. The design studied in this work includes a pivoting beam that acts to balance thrust loads produced by the helical gear meshes in each of two parallel power paths. When the thrust loads are balanced, the torque is split evenly. A mathematical model was developed to study the dynamics of the system. The effects of time varying gear mesh stiffness, static transmission errors, and flexible bearing supports are included in the model. The model was demonstrated with a test case. Results show that although the gearbox has a symmetric configuration, the simulated dynamic behavior of the first and second compound gears are not the same. Also, results show that shaft location and mesh stiffness tuning are significant design parameters that influence the motions of the system.

  12. Space Suit Joint Torque Measurement Method Validation

    NASA Technical Reports Server (NTRS)

    Valish, Dana; Eversley, Karina

    2012-01-01

    In 2009 and early 2010, a test method was developed and performed to quantify the torque required to manipulate joints in several existing operational and prototype space suits. This was done in an effort to develop joint torque requirements appropriate for a new Constellation Program space suit system. The same test method was levied on the Constellation space suit contractors to verify that their suit design met the requirements. However, because the original test was set up and conducted by a single test operator there was some question as to whether this method was repeatable enough to be considered a standard verification method for Constellation or other future development programs. In order to validate the method itself, a representative subset of the previous test was repeated, using the same information that would be available to space suit contractors, but set up and conducted by someone not familiar with the previous test. The resultant data was compared using graphical and statistical analysis; the results indicated a significant variance in values reported for a subset of the re-tested joints. Potential variables that could have affected the data were identified and a third round of testing was conducted in an attempt to eliminate and/or quantify the effects of these variables. The results of the third test effort will be used to determine whether or not the proposed joint torque methodology can be applied to future space suit development contracts.

  13. A three-dimensional model of corotating streams in the solar wind. II - Hydrodynamic streams

    NASA Technical Reports Server (NTRS)

    Pizzo, V. J.

    1980-01-01

    Theoretical aspects of corotating solar wind dynamics on a global scale are examined by means of numerical simulations executed with a nonlinear, inviscid, adiabatic, single fluid, three-dimensional hydrodynamic formulation. The factors most strongly affecting stream evolution, namely, the intrinsic correlations among density, temperature, and velocity existing near the source, the amplitude, longitudinal breadth and latitudinal breadth of the stream, and the heliographic latitude of the centroid of the stream, are considered. Calculations indicate that even in the presence of substantial meridional gradients, the latitudinal transport of mass, energy, and momentum by streams appears to have little impact on the overall evolution of the structure.

  14. Galactic Archaeology with CoRoT and APOGEE: Creating mock observations from a chemodynamical model

    NASA Astrophysics Data System (ADS)

    Anders, F.; Chiappini, C.; Rodrigues, T. S.; Piffl, T.; Mosser, B.; Miglio, A.; Montalbán, J.; Girardi, L.; Minchev, I.; Valentini, M.; Steinmetz, M.

    2016-09-01

    In a companion paper, we have presented the combined asteroseismic-spectroscopic dataset obtained from CoRoT light curves and APOGEE infra-red spectra for 606 solar-like oscillating red giants in two fields of the Galactic disc (CoRoGEE). We have measured chemical abundance patterns, distances, and ages of these field stars which are spread over a large radial range of the Milky Way's disc. Here we show how to simulate this dataset using a chemodynamical Galaxy model. We also demonstrate how the observation procedure influences the accuracy of our estimated ages.

  15. Pattern Corotation Radii from Potential-Density Phase-Shifts for 153 OSUBGS Sample Galaxies

    NASA Astrophysics Data System (ADS)

    Buta, Ronald J.; Zhang, Xiaolei

    2009-06-01

    The potential-density phase-shift method is an effective new tool for investigating the structure and evolution of galaxies. In this paper, we apply the method to 153 galaxies in the Ohio State University Bright Galaxy Survey (OSUBGS) to study the general relationship between pattern corotation radii and the morphology of spiral galaxies. The analysis is based on near-infrared H-band images that have been deprojected and decomposed assuming a spherical bulge. We find that multiple pattern speeds are common in disk galaxies. By selecting those corotation radii close to or slightly larger than the bar radius as being the bar corotation (CR) radius, we find that the average and standard deviation of the ratio R = r(CR)/r(bar), is 1.20 ± 0.52 for 101 galaxies having well-defined bars. There is an indication that this ratio depends weakly on galaxy type in the sense that the average ranges from 1.03 ± 0.37 for 65 galaxies of type Sbc and earlier, to 1.50 ± 0.63 for 36 galaxies of type Sc and later. Our bar corotation radii are on average smaller than those estimated from single-pattern-speed numerical simulations, most likely because these simulations tend to find the pattern speed which generates a density response in the gas that best matches the morphology of the outer spiral structure. Although we find CR radii in most of the sample galaxies that satisfy conventional ideas about the extent of bars, we also consider the alternative interpretation that in many cases the bar CR is actually inside the bar and that the bar ends close to its outer Lindblad resonance instead of its CR. These "superfast" bars are the most controversial finding from our study. We see evidence in the phase-shift distributions for ongoing decoupling of patterns, which hints at the formation pathways of nested patterns, and which in turn further hints at the longevity of the density wave patterns in galaxies. We also examine how uncertainties in the orientation parameters of galaxies and in

  16. CoRoT Reveals a Magnetic Activity Cycle in a Sun-Like Star

    NASA Astrophysics Data System (ADS)

    García, Rafael A.; Mathur, Savita; Salabert, David; Ballot, Jérôme; Régulo, Clara; Metcalfe, Travis S.; Baglin, Annie

    2010-08-01

    The 11-year activity cycle of the Sun is a consequence of a dynamo process occurring beneath its surface. We analyzed photometric data obtained by the CoRoT space mission, showing solarlike oscillations in the star HD49933, for signatures of stellar magnetic activity. Asteroseismic measurements of global changes in the oscillation frequencies and mode amplitudes reveal a modulation of at least 120 days, with the minimum frequency shift corresponding to maximum amplitude as in the Sun. These observations are evidence of a stellar magnetic activity cycle taking place beneath the surface of HD49933 and provide constraints for stellar dynamo models under conditions different from those of the Sun.

  17. Modelling Flow and Heat Transfer in Co-Rotating Twin-Screw Extruders

    NASA Astrophysics Data System (ADS)

    Teixeira, C.; Faria, R.; Covas, J. A.; Gaspar-Cunha, A.

    2007-04-01

    This work presents a modelling routine of co-rotating twin-screw extrusion, from hopper to die. The program accounts for a sequence of individual stages linked together by boundary conditions, namely starve-fed solids conveying, solids conveying under pressure, delay, melting, melt conveying without pressure and melt conveying under pressure. It predicts the evolution along the screw and die of temperature, shear rate, residence time, viscosity, mechanical power consumption, pressure and fill ratio. The results obtained showed adequate sensitivity to changes in operating conditions and screw geometry and are in agreement with current theoretical and experimental knowledge.

  18. Modelling a high-mass red giant observed by CoRoT

    NASA Astrophysics Data System (ADS)

    Baudin, F.; Barban, C.; Goupil, M. J.; Samadi, R.; Lebreton, Y.; Bruntt, H.; Morel, T.; Lefèvre, L.; Michel, E.; Mosser, B.; Carrier, F.; De Ridder, J.; Hatzes, A.; Hekker, S.; Kallinger, T.; Auvergne, M.; Baglin, A.; Catala, C.

    2012-02-01

    Context. The advent of space-borne photometers such as CoRoT and Kepler has opened up new fields in asteroseismology. This is especially true for red giants as only a few of these stars were known to oscillate with small amplitude, solar-like oscillations before the launch of CoRoT. Aims: The G6 giant HR 2582 (HD 50890) was observed by CoRoT for approximately 55 days. We present here the analysis of its light curve and the characterisation of the star using different observables, such as its location in the Hertzsprung-Russell diagram and seismic observables. Methods: Mode frequencies are extracted from the observed Fourier spectrum of the light curve. Numerical stellar models are then computed to determine the characteristics of the star (mass, age, etc.) from the comparison with observational constraints. Results: We provide evidence for the presence of solar-like oscillations at low frequency, between 10 and 20 μHz, with a regular spacing of (1.7 ± 0.1) μHz between consecutive radial orders. Only radial modes are clearly visible. From the models compatible with the observational constraints used here, We find that HR 2582 (HD 50890) is a massive star with a mass in the range (3-5 M⊙), clearly above the red clump. It oscillates with rather low radial order (n = 5-12) modes. Its evolutionary stage cannot be determined with precision: the star could be on the ascending red giant branch (hydrogen shell burning) with an age of approximately 155 Myr or in a later phase (helium burning). In order to obtain a reasonable helium amount, the metallicity of the star must be quite subsolar. Our best models are obtained with a mixing length significantly smaller than that obtained for the Sun with the same physical description (except overshoot). The amount of core overshoot during the main-sequence phase is found to be mild, of the order of 0.1 Hp. Conclusions: HR 2582 (HD 50890) is an interesting case as only a few massive stars can be observed due to their rapid

  19. Rotation period distribution of CoRoT and Kepler Sun-like stars

    NASA Astrophysics Data System (ADS)

    Leão, I. C.; Pasquini, L.; Ferreira Lopes, C. E.; Neves, V.; Valcarce, A. A. R.; de Oliveira, L. L. A.; Freire da Silva, D.; de Freitas, D. B.; Canto Martins, B. L.; Janot-Pacheco, E.; Baglin, A.; De Medeiros, J. R.

    2015-10-01

    Aims: We study the distribution of the photometric rotation period (Prot), which is a direct measurement of the surface rotation at active latitudes, for three subsamples of Sun-like stars: one from CoRoT data and two from Kepler data. For this purpose, we identify the main populations of these samples and interpret their main biases specifically for a comparison with the solar Prot. Methods: Prot and variability amplitude (A) measurements were obtained from public CoRoT and Kepler catalogs, which were combined with public data of physical parameters. Because these samples are subject to selection effects, we computed synthetic samples with simulated biases to compare with observations, particularly around the location of the Sun in the Hertzsprung-Russel (HR) diagram. Publicly available theoretical grids and empirical relations were used to combine physical parameters with Prot and A. Biases were simulated by performing cutoffs on the physical and rotational parameters in the same way as in each observed sample. A crucial cutoff is related with the detectability of the rotational modulation, which strongly depends on A. Results: The synthetic samples explain the observed Prot distributions of Sun-like stars as having two main populations: one of young objects (group I, with ages younger than ~1 Gyr) and another of main-sequence and evolved stars (group II, with ages older than ~1 Gyr). The proportions of groups I and II in relation to the total number of stars range within 64-84% and 16-36%, respectively. Hence, young objects abound in the distributions, producing the effect of observing a high number of short periods around the location of the Sun in the HR diagram. Differences in the Prot distributions between the CoRoT and Kepler Sun-like samples may be associated with different Galactic populations. Overall, the synthetic distribution around the solar period agrees with observations, which suggests that the solar rotation is normal with respect to Sun

  20. Switching efficiency improvement in spin torque majority gates

    SciTech Connect

    Nikonov, Dmitri E. Manipatruni, Sasikanth; Young, Ian A.

    2014-05-07

    Spin torque majority gate (STMG) is one of the promising options for beyond complementary metal-oxide-semiconductor logic. Improvement of its performance—switching speed vs. required current—is critical for its competitiveness. In this paper, (a) we identify an optimized layout of the gate comprised of thin magnetic wires with in-plane magnetization; (b) we optimize geometries of perpendicular magnetization spin torque majority gates. Micromagnetic simulations demonstrate an improvement in switching current for in-plane magnetization (with less than 1 ns switching time) from 6 mA in the original scheme to 1.5 mA in the present one. Additionally, failures of switching caused by vortex formation are eliminated and desired output magnetization is achieved. Various geometries of STMG with perpendicular magnetization are explored. The scheme with a straight cross proves to be the most advantageous. It is predicted to operate with the switching current of 50 μA and less than 4 ns switching time.

  1. Flux-Based Deadbeat Control of Induction-Motor Torque

    NASA Technical Reports Server (NTRS)

    Kenny, Barbara H.; Lorenz, Robert D.

    2003-01-01

    An improved method and prior methods of deadbeat direct torque control involve the use of pulse-width modulation (PWM) of applied voltages. The prior methods are based on the use of stator flux and stator current as state variables, leading to mathematical solutions of control equations in forms that do not lend themselves to clear visualization of solution spaces. In contrast, the use of rotor and stator fluxes as the state variables in the present improved method lends itself to graphical representations that aid in understanding possible solutions under various operating conditions. In addition, the present improved method incorporates the superposition of high-frequency carrier signals for use in a motor-self-sensing technique for estimating the rotor shaft angle at any speed (including low or even zero speed) without need for additional shaft-angle-measuring sensors.

  2. The Spin Torque Lego - from spin torque nano-devices to advanced computing architectures

    NASA Astrophysics Data System (ADS)

    Grollier, Julie

    2013-03-01

    Spin transfer torque (STT), predicted in 1996, and first observed around 2000, brought spintronic devices to the realm of active elements. A whole class of new devices, based on the combined effects of STT for writing and Giant Magneto-Resistance or Tunnel Magneto-Resistance for reading has emerged. The second generation of MRAMs, based on spin torque writing : the STT-RAM, is under industrial development and should be out on the market in three years. But spin torque devices are not limited to binary memories. We will rapidly present how the spin torque effect also allows to implement non-linear nano-oscillators, spin-wave emitters, controlled stochastic devices and microwave nano-detectors. What is extremely interesting is that all these functionalities can be obtained using the same materials, the exact same stack, simply by changing the device geometry and its bias conditions. So these different devices can be seen as Lego bricks, each brick with its own functionality. During this talk, I will show how spin torque can be engineered to build new bricks, such as the Spintronic Memristor, an artificial magnetic nano-synapse. I will then give hints on how to assemble these bricks in order to build novel types of computing architectures, with a special focus on neuromorphic circuits. Financial support by the European Research Council Starting Grant NanoBrain (ERC 2010 Stg 259068) is acknowledged.

  3. OBSERVATIONS OF BINARY STARS WITH THE DIFFERENTIAL SPECKLE SURVEY INSTRUMENT. IV. OBSERVATIONS OF KEPLER, CoRoT, AND HIPPARCOS STARS FROM THE GEMINI NORTH TELESCOPE

    SciTech Connect

    Horch, Elliott P.; Howell, Steve B.; Everett, Mark E.; Ciardi, David R. E-mail: steve.b.howell@nasa.gov E-mail: ciardi@ipac.caltech.edu

    2012-12-01

    We present the results of 71 speckle observations of binary and unresolved stars, most of which were observed with the DSSI speckle camera at the Gemini North Telescope in 2012 July. The main purpose of the run was to obtain diffraction-limited images of high-priority targets for the Kepler and CoRoT missions, but in addition, we observed a number of close binary stars where the resolution limit of Gemini was used to better determine orbital parameters and/or confirm results obtained at or below the diffraction limit of smaller telescopes. Five new binaries and one triple system were discovered, and first orbits are calculated for other two systems. Several systems are discussed in detail.

  4. Strong orbital expansion of Saturn’s inner ice-rich moons through ring torques and mutual resonances during their accretion from a massive ring

    NASA Astrophysics Data System (ADS)

    Salmon, Julien; Canup, Robin M.

    2015-11-01

    Saturn has a diversity of moons with possibly diverse origins. Titan likely formed in Saturn’s sub-nebula (e.g., Canup & Ward 2006). The small moons interior to Mimas are likely recent aggregates of ring’s material spreading through the Roche limit (Charnoz et al. 2010). The origin of the mid-size moons, Mimas through Rhea, is debated. Charnoz et al. (2011) considered a massive ice-rock ring and strong tidal dissipation in Saturn (Q ~ 103), and found that moons out to Rhea could be spawned from such a ring. However such a small value for Q for Saturn is debated. In addition, capture into mutual Mean Motion Resonances (MMR) and resulting eccentricity growth (not included in the Charnoz et al. (2011) model) could lead to orbital destabilization as the moons tidally expand over such large distances (Peale & Canup 2015).Here we consider weak planetary tides (Q ≥ 104) and investigate whether Mimas, Enceladus and Tethys could have been spawned from a massive ice ring (Canup 2010). In this scenario, the rock in these moons would be delivered by material from outside the rings, e.g. by heliocentric impactors during the LHB (Canup 2013). We have expanded a numerical model developed to study the Moon’s accretion (Salmon and Canup 2012, 2014), which couples an analytic Roche-interior disk model to the N-body code SyMBA (Duncan et al. 1998) for satellites, so that we can directly track their accretion and mutual interactions (including MMRs), as well as their tidal interaction with the planet. We consider an initially large Saturn (Fortney et al. 2007) and its progressive contraction, which impacts the strength of tides and the location of the corotation resonance. We perform simulations with and without Dione and Rhea, and study the influence of tidal dissipation into the moons.We find that recoil of the moons due to ring torques, together with capture of moons into MMRs, can produce a distribution similar to that observed. If tidal dissipation in the moons was weak

  5. Torque Ripple Reduction in Direct Torque Control Based Induction Motor using Intelligent Controllers

    NASA Astrophysics Data System (ADS)

    Sudhakar, Ambarapu; Vijaya Kumar, M.

    2015-09-01

    This paper presents intelligent control scheme together with conventional control scheme to overcome the problems with uncertainties in the structure encountered with classical model based design of induction motor drive based on direct torque control (DTC). It allows high dynamic performance to be obtained with very simple hysteresis control scheme. Direct control of the torque and flux is achieved by proper selection of inverter voltage space vector through a lookup table. This paper also presents the application of intelligent controllers like neural network and fuzzy logic controllers to control induction machines with DTC. Intelligent controllers are used to emulate the state selector of the DTC. With implementation of intelligent controllers the system is also verified and proved to be operated stably with reduced torque ripple. The proposed method validity and effectiveness has been verified by computer simulations using Matlab/Simulink®. These results are compared with the ones obtained with a classical DTC using proportional integral speed controller.

  6. Development of infant leg coordination: Exploiting passive torques.

    PubMed

    Sargent, Barbara; Scholz, John; Reimann, Hendrik; Kubo, Masayoshi; Fetters, Linda

    2015-08-01

    Leg joint coordination systematically changes over the first months of life, yet there is minimal data on the underlying change in muscle torques that might account for this change in coordination. The purpose of this study is to investigate the contribution of torque changes to early changes in leg joint coordination. Kicking actions were analyzed of 10 full-term infants between 6 and 15-weeks of age using three-dimensional kinematics and kinetics. We found 11 of 15 joint angle pairs demonstrated a change from more in-phase intralimb coordination at 6-weeks to less in-phase coordination at 15-weeks. Although the magnitude of joint torques normalized to the mass of the leg remained relatively consistent, we noted more complex patterns of torque component contribution across ages. By focusing on the change in torques associated with hip-knee joint coordination, we found that less in-phase hip-knee joint coordination at 15-weeks was associated with decreased influence of knee muscle torque and increased influence of knee gravitational and motion-dependent torques, supporting that infants coordinate hip muscle torque with passive knee gravitational and motion-dependent torques to generate kicks with reduced active knee muscle torque. We propose that between 6 and 15-weeks of age less in-phase hip-knee coordination emerges as infants exploit passive dynamics in the coordination of hip and knee motions.

  7. Bevel gear driver and method having torque limit selection

    NASA Technical Reports Server (NTRS)

    Cook, Joseph S., Jr. (Inventor)

    1994-01-01

    This invention comprises a torque drive mechanism utilizing axially translatable, mutually engageable transmission members having mating crown gears, driven and driving members with a three-element drive train being biased together by resilient means or by a fluid actuator system, the apparatus being operable to transmit a precisely controlled degree of torque to a driven member. The apparatus is applicable for use in hand tools and as a replacement for impact torque drivers, torque wrenches, motorized screw drivers, or the like, wherein the applied torque must be precisely controlled or limited. The bevel torque drive includes a drive gear which is axially displaceable and rotatable within cylindrical driver housing, a rotatable intermediate gear, and an output gear. Key rotationally secures displaceable gear with respect to input shaft but permits axial movement therebetween. A thrust bearing is preferably connected to the lower end of shaft for support to reduce play and friction between shaft and a transmission joint disc during rotation of the gear train. Coaxially mounted coiled spring is footed against displaceable gear for biasing the displaceable gear toward and into engagement with the intermediate gear for driving intermediate gear and output gear. Torque control is achieved by the use of straight or spiral beveled gears which are of configurations adapted to withdraw from mutual engagement upon the torque exceeding a predetermined limit. The novel, advantageous features of the invention include the configuration of the mating, crown gear sets and the axially translatable, slidable drive gear. The mechanism is capable of transmitting a high degree of torque within a narrow, compact transmission housing. The compact size and narrow, elongated configuration of the housing is particularly applicable for use in hand tools and in multiple torque driver mechanisms in which it is necessary to drive multiple fasteners which are located in close proximity. Prior

  8. The stellar kinematics of corotating spiral arms in Gaia mock observations

    NASA Astrophysics Data System (ADS)

    Hunt, Jason A. S.; Kawata, Daisuke; Grand, Robert J. J.; Minchev, Ivan; Pasetto, Stefano; Cropper, Mark

    2015-06-01

    We have observed an N-body/smoothed particle hydrodynamics simulation of a Milky Way-like barred spiral galaxy. We present a simple method that samples N-body model particles into mock Gaia stellar observations and takes into account stellar populations, dust extinction and Gaia's science performance estimates. We examine the kinematics of stars with V ≤ 16 mag around a nearby spiral arm at a similar position to the Perseus arm at three lines of sight in the disc plane; (l, b) = (90, 0), (120, 0) and (150, 0) deg. We find that the structure of the peculiar kinematics around the corotating spiral arm, which is found in Kawata et al. (2014b), is still visible in the observational data expected to be produced by Gaia, despite the dust extinction and expected observational errors of Gaia. These observable kinematic signatures will enable testing whether the Perseus arm of the Milky Way is similar to the corotating spiral arms commonly seen in N-body simulations.

  9. Search for Exomoons and Rings with Kepler and CoRoT

    NASA Astrophysics Data System (ADS)

    Moretto Tusnski, Luis Ricardo; Silva Valio, Adriana

    2015-08-01

    After almost 20 years since the first exoplanet discoveries, new techniques have been developed and high precision has been achieved, which lead to a large number of small planets detected. Recently, some researchers are trying to detect exomoons: moons around exoplanets. Some methods have been proposed and studied, and the most likely to lead to a discovery is the planetary transit technique. Exomoons cause two types of effects in the planet transit light curve: photometric signatures and transit timing effects. Despite the searches and methods proposed, so far no moon has been found around exoplanets. One reason for this is the small number of searches been conducted. In this work, we present an independent serch project called PSER - Photometric Search for Exomoons and Rings. As the name states, this project looks for exomoons and exorings in Kepler and CoRoT lightcurves. To do so, we developed a program to look for exomoons signals automatically, using MCMC to fit the lightcurves. We started our search with Kepler and CoRoT confirmed single planets. After that, we will also look in Kepler Planetary Candidates. So far, no signal has been found.

  10. Physical state of the deep interior of the CoRoT-7b exoplanet

    NASA Astrophysics Data System (ADS)

    Wagner, Frank W.; Sohl, Frank; Rückriemen, Tina; Rauer, Heike

    2011-11-01

    The present study takes the CoRoT-7b exoplanet as an analogue for massive terrestrial planets to investigate conditions, under which intrinsic magnetic fields could be sustained in liquid cores. We examine the effect of depth-dependent transport parameters (e.g., activation volume of mantle rock) on a planet's thermal structure and the related heat flux across the core mantle boundary. For terrestrial planets more massive than the Earth, our calculations suggest that a substantial part of the lowermost mantle is in a sluggish convective regime, primarily due to pressure effects on viscosity. Hence, we find substantially higher core temperatures than previously reported from parameterized convection models. We also discuss the effect of melting point depression in the presence of impurities (e.g., sulfur) in iron-rich cores and compare corresponding melting relations to the calculated thermal structure. Since impurity effects become less important at the elevated pressure and temperature conditions prevalent in the deep interior of CoRoT-7b, iron-rich cores are likely solid, implying that a self-sustained magnetic field would be absent.

  11. Implications of the Corotation Theorem on the MRI in Axial Symmetry

    NASA Astrophysics Data System (ADS)

    Montani, G.; Cianfrani, F.; Pugliese, D.

    2016-08-01

    We analyze the linear stability of an axially symmetric ideal plasma disk, embedded in a magnetic field and endowed with a differential rotation. This study is performed by adopting the magnetic flux function as the fundamental dynamical variable, in order to outline the role played by the corotation theorem on the linear mode structure. Using some specific assumptions (e.g., plasma incompressibility and propagation of the perturbations along the background magnetic field), we select the Alfvénic nature of the magnetorotational instability, and, in the geometric optics limit, we determine the dispersion relation describing the linear spectrum. We show how the implementation of the corotation theorem (valid for the background configuration) on the linear dynamics produces the cancellation of the vertical derivative of the disk angular velocity (we check such a feature also in the standard vector formalism to facilitate comparison with previous literature, in both the axisymmetric and three-dimensional cases). As a result, we clarify that the unstable modes have, for a stratified disk, the same morphology, proper of a thin-disk profile, and the z-dependence has a simple parametric role.

  12. Modeling transport of energetic particles in corotating interaction regions: A case study

    NASA Astrophysics Data System (ADS)

    Zhao, Lulu; Li, Gang; Ebert, R. W.; Dayeh, M. A.; Desai, M. I.; Mason, G. M.; Wu, Z.; Chen, Y.

    2016-01-01

    We investigate energetic particle transport in corotating interaction regions (CIRs) through a case study. The CIR event we study occurred on 8 February 2008 and was observed by both the Advanced Composition Explorer (ACE) and the twin Solar TErrestrial RElations Observatory (STEREO) B spacecraft. An in situ reverse shock was observed by STEREO B (1.0 AU) but not ACE (0.98 AU). Using STEREO B observations and assuming the CIR structure does not vary significantly in the corotating frame, we estimate the shock location at later times for both the STEREO B and ACE observations. Further assuming the accelerated particle spectral shape at the shock does not vary with shock location, we calculate the particle differential intensities as observed by ACE and STEREO B at two different times by solving the focused transport equation using a Monte Carlo simulation. We assume that particles move along Parker's field and experience no cross-field diffusion. We find that the modulation of sub-MeV/nucleon particles is significant. To obtain reasonable comparisons between the simulations and the observations by both ACE and STEREO B, one has to assume that the CIR shock can accelerate more particles at a larger heliocentric distance than at a smaller heliocentric distance.

  13. Solar Wind Interaction with Comet 67P/C-G: Impact of Corotating Interaction Regions

    NASA Astrophysics Data System (ADS)

    Edberg, N. J. T.; Eriksson, A. I.; Odelstad, E.; Vigren, E.; Burch, J. L.; Carr, C.; Cupido, E.; Glassmeier, K. H.; Goldstein, R.; Halekas, J. S.; Pierre, H.; Lebreton, J. P.; Mandt, K.; Mokashi, P.; Nemeth, Z.; Nilsson, H.; Ramstad, R.; Richter, I.; Stenberg Wieser, G.

    2015-12-01

    We present observations from the Rosetta Plasma Consortium (RPC) of impacts of corotating interaction regions (CIRs) on comet 67P. Corotating interaction regions build up in the solar wind when slow flow is caught up by faster flow. A pressure pulse is then formed, which propagates outward in interplanetary space and impacts on e.g. planets, moons and comet in its path. In the interval October to December 2014 four such CIRs are traced from Earth (using ACE) to Mars (using Mars Express and MAVEN) and to comet 67P (using Rosetta). As the CIRs impact on the cometary coma the ionospheric low-energy plasma density in the ionosphere increases by roughly one order of magnitude in the first three events. The increased density is possibly caused by sweeping up of more upstream plasma in combination with increased impact ionization and charge exchange processes. Increased fluxes of ~100 eV electrons are observed concurrently and the magnetic field strength typically doubles as more interplanetary magnetic field piles up around of the comet.

  14. Optical and mechanical design of a straylight rejection baffle for CoRoT

    NASA Astrophysics Data System (ADS)

    Plesseria, Jean-Yves; Mazy, Emmanuel; Defise, Jean-Marc; Rochus, Pierre; Lemmens, Els; Vrancken, Davy

    2003-11-01

    The COROT mission is part of the program "Petites Missions" of CNES (French space agency). It implies international cooperation between France, Belgium, Germany, Austria, Spain and the European Space Agency (ESA). COROT aims to perform astroseismology measurements and to detect exoplanets. Long duration observations of stars will be used to detect periodic variations with an afocal telescope followed by a dioptric objective and 4 CCDs. Due to the orbit of the spacecraft (low altitude polar orbit) and even if the observation are performed in a direction perpendicular to orbit plane, the measurements can be disturbed by the straylight reflected on the earth (albedo) that can generate periodic perturbation. CSL is in charge of the design and procurement, with the help of Belgian industries, of a baffle and its protective cover that will be mounted on top of the afocal entrance telescope. The requirements are very stringent from the optical point of view as well as from the mechanical point of view. The rejection of the baffle must be of the order of 1013 for field angles above 20 degrees while the allocated mass is 19 kilograms.

  15. None of the Rotor Residues of F1-ATPase Are Essential for Torque Generation

    PubMed Central

    Chiwata, Ryohei; Kohori, Ayako; Kawakami, Tomonari; Shiroguchi, Katsuyuki; Furuike, Shou; Adachi, Kengo; Sutoh, Kazuo; Yoshida, Masasuke; Kinosita, Kazuhiko

    2014-01-01

    F1-ATPase is a powerful rotary molecular motor that can rotate an object several hundred times as large as the motor itself against the viscous friction of water. Forced reverse rotation has been shown to lead to ATP synthesis, implying that the mechanical work against the motor’s high torque can be converted into the chemical energy of ATP. The minimal composition of the motor protein is α3β3γ subunits, where the central rotor subunit γ turns inside a stator cylinder made of alternately arranged α3β3 subunits using the energy derived from ATP hydrolysis. The rotor consists of an axle, a coiled coil of the amino- and carboxyl-terminal α-helices of γ, which deeply penetrates the stator cylinder, and a globular protrusion that juts out from the stator. Previous work has shown that, for a thermophilic F1, significant portions of the axle can be truncated and the motor still rotates a submicron sized bead duplex, indicating generation of up to half the wild-type (WT) torque. Here, we inquire if any specific interactions between the stator and the rest of the rotor are needed for the generation of a sizable torque. We truncated the protruding portion of the rotor and replaced part of the remaining axle residues such that every residue of the rotor has been deleted or replaced in this or previous truncation mutants. This protrusionless construct showed an unloaded rotary speed about a quarter of the WT, and generated one-third to one-half of the WT torque. No residue-specific interactions are needed for this much performance. F1 is so designed that the basic rotor-stator interactions for torque generation and control of catalysis rely solely upon the shape and size of the rotor at very low resolution. Additional tailored interactions augment the torque to allow ATP synthesis under physiological conditions. PMID:24853745

  16. The variability behaviour of CoRoT M-giant stars⋆

    NASA Astrophysics Data System (ADS)

    Ferreira Lopes, C. E.; Neves, V.; Leão, I. C.; de Freitas, D. B.; Canto Martins, B. L.; da Costa, A. D.; Paz-Chinchón, F.; Das Chagas, M. L.; Baglin, A.; Janot-Pacheco, E.; De Medeiros, J. R.

    2015-11-01

    Context. For six years the Convection, Rotation, and planetary Transits (CoRoT) space mission has been acquiring photometric data from more than 100 000 point sources towards and directly opposite the inner and outer regions of the Galaxy. The high temporal resolution of the CoRoT data, combined with the wide time span of the observations, enabled the study of short- and long-time variations in unprecedented detail. Aims: The aim of this work is to study the variability and evolutionary behaviour of M-giant stars using CoRot data. Methods: From the initial sample of 2534 stars classified as M giants in the CoRoT databases, we selected 1428 targets that exhibit well defined variability, by visual inspection. Then, we defined three catalogues: C1 - stars with Teff< 4200 K and LCs displaying semi-sinusoidal signatures; C2 - rotating variable candidates with Teff> 4200 K; C3 - long-period variable candidates (with LCs showing a variability period up to the total time span of the observations). The variability period and amplitude of C1 stars were computed using Lomb-Scargle and harmonic fit methods. Finally, we used C1 and C3 stars to study the variability behaviour of M-giant stars. Results: The trends found in the V-I vs. J-K colour-colour diagram are in agreement with standard empirical calibrations for M giants. The sources located towards the inner regions of the Galaxy are distributed throughout the diagram, while the majority of the stars towards the outer regions of the Galaxy are spread between the calibrations of M giants and the predicted position for carbon stars. The stars classified as supergiants follow a different sequence from the one found for giant stars. We also performed a Kolmogorov-Smirnov (KS) test of the period and amplitude of stars towards the inner and outer regions of the Galaxy. We obtained a low probability that the two samples came from the same parent distribution. The observed behaviour of the period-amplitude and period

  17. Acoustic Interaction Forces and Torques Acting on Suspended Spheres in an Ideal Fluid.

    PubMed

    Lopes, J Henrique; Azarpeyvand, Mahdi; Silva, Glauber T

    2016-01-01

    In this paper, the acoustic interaction forces and torques exerted by an arbitrary time-harmonic wave on a set of N objects suspended in an inviscid fluid are theoretically analyzed. We utilize the partial-wave expansion method with translational addition theorem and re-expansion of multipole series to solve the related multiple scattering problem. We show that the acoustic interaction force and torque can be obtained using the farfield radiation force and torque formulas. To exemplify the method, we calculate the interaction forces exerted by an external traveling and standing plane wave on an arrangement of two and three olive-oil droplets in water. The droplets' radii are comparable to the wavelength (i.e., Mie scattering regime). The results show that the acoustic interaction forces present an oscillatory spatial distribution which follows the pattern formed by interference between the external and rescattered waves. In addition, acoustic interaction torques arise on the absorbing droplets whenever a nonsymmetric wavefront is formed by the external and rescattered waves' interference.

  18. The effect of knee joint angle on torque control.

    PubMed

    Sosnoff, Jacob J; Voudrie, Stefani J; Ebersole, Kyle T

    2010-01-01

    The purpose of the author's investigation was to examine the effect of knee joint angle on torque control of the quadriceps muscle group. In all, 12 healthy adults produced maximal voluntary contractions and submaximal torque (15, 30, and 45% MVC [maximal voluntary contraction]) at leg flexion angles of 15 degrees , 30 degrees , 60 degrees , and 90 degrees below the horizontal plane. As expected, MVC values changed with respect to joint angle with maximum torque output being greatest at 60 degrees and least at 15 degrees . During the submaximal tasks, participants appropriately scaled their torque output to the required targets. Absolute variability (i.e., standard deviation) of torque output was greatest at 60 degrees and 90 degrees knee flexion. However, relative variability as indexed by coefficient of variation (CV) decreased as joint angle increased, with the greatest CV occurring at 15 degrees . These results are congruent with the hypothesis that joint angle influences the control of torque.

  19. Torque resolver design for tendon-driven manipulators

    SciTech Connect

    Lee, J.J.; Tsai, Lung-Wen.

    1992-01-01

    Given a set of desired joint torques in an n-DOF tendon-driven manipulator with n + 1 control tendons, the determination of tendon forces is an indeterminate problem. Usually, the pseudo-inverse technique is used to solve for such a problem. In this paper, rather than using the pseudo-inverse technique is used to solve for such a problem. In this paper, rather than using the pseudo-inverse technique, an efficient methodology for transforming joint torques (n elements) to motor torques (n + 1 elements) has been developed. This technique called torque resolver'', utilizes two circuit-like operators to transform torques between the two different vector spaces. It can be easily programmed on a digital computer or implemented into an analog-circuit system. It is hoped that this technique will make real-time computed-torque control feasible. The technique has been demonstrated through the dynamic simulation of a three-DOF manipulator.

  20. Torque resolver design for tendon-driven manipulators

    SciTech Connect

    Lee, J.J.; Tsai, Lung-Wen

    1992-08-01

    Given a set of desired joint torques in an n-DOF tendon-driven manipulator with n + 1 control tendons, the determination of tendon forces is an indeterminate problem. Usually, the pseudo-inverse technique is used to solve for such a problem. In this paper, rather than using the pseudo-inverse technique is used to solve for such a problem. In this paper, rather than using the pseudo-inverse technique, an efficient methodology for transforming joint torques (n elements) to motor torques (n + 1 elements) has been developed. This technique called ``torque resolver``, utilizes two circuit-like operators to transform torques between the two different vector spaces. It can be easily programmed on a digital computer or implemented into an analog-circuit system. It is hoped that this technique will make real-time computed-torque control feasible. The technique has been demonstrated through the dynamic simulation of a three-DOF manipulator.

  1. Bevel Gear Driver and Method Having Torque Limit Selection

    NASA Technical Reports Server (NTRS)

    Cook, Joseph S., Jr. (Inventor)

    1997-01-01

    Methods and apparatus are provided for a torque driver including an axially displaceable gear with a biasing assembly to bias the displaceable gear into an engagement position. A rotatable cap is provided with a micrometer dial to select a desired output torque. An intermediate bevel gear assembly is disposed between an input gear and an output gear. A gear tooth profile provides a separation force that overcomes the bias to limit torque at a desired torque limit. The torque limit is adjustable and may be adjusted manually or automatically depending on the type of biasing assembly provided. A clutch assembly automatically limits axial force applied to a fastener by the operator to avoid alteration of the desired torque limit.

  2. Torque sensor for internal-combustion engine

    SciTech Connect

    Kay, I.W.; Lehrach, R.P.C.

    1987-09-01

    This patent describes an apparatus for providing a measure of the torque of an internal-combustion engine having a rotating crankshaft for connection to a load, the crankshaft undergoing acceleration/deceleration sub-cycles associated with respective firing intervals within an engine cycle. The sensor consists of: means for providing electrical signals indicating occurrence of particular angular positions of the crankshaft in an engine cycle; electronic signal processing means responsive to the signals indicative of a crankshaft angle for providing signals, N/sub i/, indicative of instantaneous sub-cyclic engine speed at each of a plurality of predetermined crankshaft angles in an engine cycle, the plurality of predetermined crankshaft angles including a respective pair of angles for each firing interval, the respective two crankshaft angles of each pair being spaced from one another by an angle corresponding with substantially one-half of a firing interval, for providing in response to the sub-cyclic engine speed signals, N/sub i/, further signals, ..delta..N/sub i/; representative of the average of the difference between instantaneous engine speeds of the two crank angles of each respective pair of crankshaft angles within an engine cycle, for providing signals, N/sub avg/, indicative of average engine speed, and for generating a torque signal, T, as a function of the average engine speed signal N/sub avg/, and the average instantaneous engine speed difference signal, ..delta..N/sub i/, and electrical utilization means having the torque signal, T, operatively connected as an input thereto.

  3. Effect of environmental torques on short-term attitude prediction for a rolling-wheel spacecraft in a sun-synchronous orbit

    NASA Technical Reports Server (NTRS)

    Hodge, W. F.

    1972-01-01

    A numerical evaluation and an analysis of the effects of environmental disturbance torques on the attitude of a hexagonal cylinder rolling wheel spacecraft were performed. The resulting perturbations caused by five such torques were found to be very small and exhibited linearity such that linearized equations of motion yielded accurate results over short periods and the separate perturbations contributed by each torque were additive in the sense of superposition. Linearity of the torque perturbations was not affected by moderate system design changes and persisted for torque-to-angular momentum ratios up to 100 times the nominal expected value. As these conditions include many possible applications, similar linear behavior might be anticipated for other rolling-wheel spacecraft.

  4. Torque generation by the flagellar rotary motor.

    PubMed Central

    Berg, H C

    1995-01-01

    A review is given of the structure and dynamics of the flagellar rotary motor. Force-generating elements in a motor driving a tethered bacterium (a cell fixed to the substratum by a single flagellum) exert forces of order 20 pN while moving at speeds of order 1 micron/s. Force-generating elements in a motor driving a flagellar filament in a bundle exert forces some 10-fold lower but move at speeds more than 10-fold higher. The motor torque-speed relationship has been measured over a wide dynamic range. Motors strongly resist being driven backwards and are easily broken. PMID:7787060

  5. Torque-induced precession of bacterial flagella

    NASA Astrophysics Data System (ADS)

    Shimogonya, Yuji; Sawano, Yoichiro; Wakebe, Hiromichi; Inoue, Yuichi; Ishijima, Akihiko; Ishikawa, Takuji

    2015-12-01

    The bacterial flagellar motor is an ion-driven rotary machine in the cell envelope of bacteria. Using a gold nanoparticle as a probe, we observed the precession of flagella during rotation. Since the mechanism of flagella precession was unknown, we investigated it using a combination of full simulations, theory, and experiments. The results show that the mechanism can be well explained by fluid mechanics. The validity of our theory was confirmed by our full simulation, which was utilized to predict both the filament tilt angle and motor torque from experimental flagellar precession data. The knowledge obtained is important in understanding mechanical properties of the bacterial motor and hook.

  6. Torque-induced precession of bacterial flagella.

    PubMed

    Shimogonya, Yuji; Sawano, Yoichiro; Wakebe, Hiromichi; Inoue, Yuichi; Ishijima, Akihiko; Ishikawa, Takuji

    2015-01-01

    The bacterial flagellar motor is an ion-driven rotary machine in the cell envelope of bacteria. Using a gold nanoparticle as a probe, we observed the precession of flagella during rotation. Since the mechanism of flagella precession was unknown, we investigated it using a combination of full simulations, theory, and experiments. The results show that the mechanism can be well explained by fluid mechanics. The validity of our theory was confirmed by our full simulation, which was utilized to predict both the filament tilt angle and motor torque from experimental flagellar precession data. The knowledge obtained is important in understanding mechanical properties of the bacterial motor and hook. PMID:26691402

  7. Small-Bolt Torque-Tension Tester

    NASA Technical Reports Server (NTRS)

    Posey, Alan J.

    2009-01-01

    The device described here measures the torque-tension relationship for fasteners as small as #0. The small-bolt tester consists of a plate of high-strength steel into which three miniature load cells are recessed. The depth of the recess is sized so that the three load cells can be shimmed, the optimum height depending upon the test hardware. The three miniature load cells are arranged in an equilateral triangular configuration with the test bolt aligned with the centroid of the three. This is a kinematic arrangement.

  8. Torque-induced precession of bacterial flagella

    PubMed Central

    Shimogonya, Yuji; Sawano, Yoichiro; Wakebe, Hiromichi; Inoue, Yuichi; Ishijima, Akihiko; Ishikawa, Takuji

    2015-01-01

    The bacterial flagellar motor is an ion-driven rotary machine in the cell envelope of bacteria. Using a gold nanoparticle as a probe, we observed the precession of flagella during rotation. Since the mechanism of flagella precession was unknown, we investigated it using a combination of full simulations, theory, and experiments. The results show that the mechanism can be well explained by fluid mechanics. The validity of our theory was confirmed by our full simulation, which was utilized to predict both the filament tilt angle and motor torque from experimental flagellar precession data. The knowledge obtained is important in understanding mechanical properties of the bacterial motor and hook. PMID:26691402

  9. Electronic measurement of variable torques in precision work technology

    NASA Technical Reports Server (NTRS)

    Maehr, M.

    1978-01-01

    Approaches for the determination of torques on the basis of length measurements are discussed. Attention is given to torque determinations in which the deformation of a shaft is measured, an electric measurement of the torsion angle, and an approach proposed by Buschmann (1970). Methods for a torque determination conducted with the aid of force measurements make use of piezoelectric approaches. The components used by these methods include a quartz crystal and a charge amplifier.

  10. Polarity-dependent dielectric torque in nematic liquid crystals.

    PubMed

    Gu, Mingxia; Shiyanovskii, Sergij V; Lavrentovich, Oleg D

    2008-06-13

    The dielectric dispersion in the uniaxial nematic liquid crystals affects the switching dynamics of the director, as the dielectric torque is determined by not only the present values of the electric field and director but also by their past values. We demonstrate that this "dielectric memory" leads to an unusual contribution to the dielectric torque that is linear in the present field and thus polarity sensitive. This torque can be used to accelerate the "switch-off" phase of director dynamics.

  11. Domain wall oscillations induced by spin torque in magnetic nanowires

    SciTech Connect

    Sbiaa, R.; Chantrell, R. W.

    2015-02-07

    Using micromagnetic simulations, the effects of the non-adiabatic spin torque (β) and the geometry of nanowires on domain wall (DW) dynamics are investigated. For the case of in-plane anisotropy nanowire, it is observed that the type of DW and its dynamics depends on its dimension. For a fixed length, the critical switching current decreases almost exponentially with the width W, while the DW speed becomes faster for larger W. For the case of perpendicular anisotropy nanowire, it was observed that DW dynamics depends strongly on β. For small values of β, oscillations of DW around the center of nanowire were revealed even after the current is switched off. In addition to nanowire geometry and intrinsic material properties, β could provide a way to control DW dynamics.

  12. Vibration-induced extra torque during electrically-evoked contractions of the human calf muscles

    PubMed Central

    2010-01-01

    Background High-frequency trains of electrical stimulation applied over the lower limb muscles can generate forces higher than would be expected from a peripheral mechanism (i.e. by direct activation of motor axons). This phenomenon is presumably originated within the central nervous system by synaptic input from Ia afferents to motoneurons and is consistent with the development of plateau potentials. The first objective of this work was to investigate if vibration (sinusoidal or random) applied to the Achilles tendon is also able to generate large magnitude extra torques in the triceps surae muscle group. The second objective was to verify if the extra torques that were found were accompanied by increases in motoneuron excitability. Methods Subjects (n = 6) were seated on a chair and the right foot was strapped to a pedal attached to a torque meter. The isometric ankle torque was measured in response to different patterns of coupled electrical (20-Hz, rectangular 1-ms pulses) and mechanical stimuli (either 100-Hz sinusoid or gaussian white noise) applied to the triceps surae muscle group. In an additional investigation, Mmax and F-waves were elicited at different times before or after the vibratory stimulation. Results The vibratory bursts could generate substantial self-sustained extra torques, either with or without the background 20-Hz electrical stimulation applied simultaneously with the vibration. The extra torque generation was accompanied by increased motoneuron excitability, since an increase in the peak-to-peak amplitude of soleus F waves was observed. The delivery of electrical stimulation following the vibration was essential to keep the maintained extra torques and increased F-waves. Conclusions These results show that vibratory stimuli applied with a background electrical stimulation generate considerable force levels (up to about 50% MVC) due to the spinal recruitment of motoneurons. The association of vibration and electrical stimulation could be

  13. Current-induced spin torque resonance of a magnetic insulator

    NASA Astrophysics Data System (ADS)

    Schreier, Michael; Chiba, Takahiro; Niedermayr, Arthur; Lotze, Johannes; Huebl, Hans; Geprägs, Stephan; Takahashi, Saburo; Bauer, Gerrit E. W.; Gross, Rudolf; Goennenwein, Sebastian T. B.

    2015-10-01

    We report the observation of current-induced spin torque resonance in yttrium iron garnet/platinum bilayers. An alternating charge current at GHz frequencies in the platinum gives rise to dc spin pumping and spin Hall magnetoresistance rectification voltages, induced by the Oersted fields of the ac current and the spin Hall effect-mediated spin transfer torque. In ultrathin yttrium iron garnet films, we observe spin transfer torque actuated magnetization dynamics which are significantly larger than those generated by the ac Oersted field. Spin transfer torques thus efficiently couple charge currents and magnetization dynamics also in magnetic insulators, enabling charge current-based interfacing of magnetic insulators with microwave devices.

  14. Are joint torque models limited by an assumption of monoarticularity?

    PubMed

    Lewis, Martin G C; King, Mark A; Yeadon, Maurice R; Conceição, Filipe

    2012-11-01

    This study determines whether maximal voluntary ankle plantar flexor torque could be more accurately represented using a torque generator that is a function of both knee and ankle kinematics. Isovelocity and isometric ankle plantar flexor torques were measured on a single participant for knee joint angles of 111° to 169° (approximately full extension) using a Contrex MJ dynamometer. Maximal voluntary torque was represented by a 19-parameter two-joint function of ankle and knee joint angles and angular velocities with the parameters determined by minimizing a weighted root mean square difference between measured torques and the two-joint function. The weighted root mean square difference between the two-joint function and the measured torques was 10 N-m or 3% of maximum torque. The two-joint function was a more accurate representation of maximal voluntary ankle plantar flexor torques than an existing single-joint function where differences of 19% of maximum torque were found. It is concluded that when the knee is flexed by more than 40°, a two-joint representation is necessary.

  15. Maximum Torque and Momentum Envelopes for Reaction Wheel Arrays

    NASA Technical Reports Server (NTRS)

    Reynolds, R. G.; Markley, F. Landis

    2001-01-01

    Spacecraft reaction wheel maneuvers are limited by the maximum torque and/or angular momentum which the wheels can provide. For an n-wheel configuration, the torque or momentum envelope can be obtained by projecting the n-dimensional hypercube, representing the domain boundary of individual wheel torques or momenta, into three dimensional space via the 3xn matrix of wheel axes. In this paper, the properties of the projected hypercube are discussed, and algorithms are proposed for determining this maximal torque or momentum envelope for general wheel configurations. Practical implementation strategies for specific wheel configurations are also considered.

  16. Spin reversal and orbital torques on a viscous fluid Rayleigh sphere located arbitrarily in acoustical Bessel vortex (spiraling) beams.

    PubMed

    Mitri, F G

    2016-12-01

    negative spin torque generation may be exploited from the standpoint of particle sizing, and possibly other applications in particle manipulation and rotation. In addition, an application of the spin and orbital radiation torque formulations derived here in the Rayleigh limit concerns the inverse determination of the host fluid viscosity from the induced sphere spinning and/or orbital rotation.

  17. Spin reversal and orbital torques on a viscous fluid Rayleigh sphere located arbitrarily in acoustical Bessel vortex (spiraling) beams.

    PubMed

    Mitri, F G

    2016-12-01

    negative spin torque generation may be exploited from the standpoint of particle sizing, and possibly other applications in particle manipulation and rotation. In addition, an application of the spin and orbital radiation torque formulations derived here in the Rayleigh limit concerns the inverse determination of the host fluid viscosity from the induced sphere spinning and/or orbital rotation. PMID:27479229

  18. High Altitude Increases Alteration in Maximal Torque but Not in Rapid Torque Development in Knee Extensors after Repeated Treadmill Sprinting.

    PubMed

    Girard, Olivier; Brocherie, Franck; Millet, Grégoire P

    2016-01-01

    We assessed knee extensor neuromuscular adjustments following repeated treadmill sprints in different normobaric hypoxia conditions, with special reference to rapid muscle torque production capacity. Thirteen team- and racquet-sport athletes undertook 8 × 5-s "all-out" sprints (passive recovery = 25 s) on a non-motorized treadmill in normoxia (NM; FiO2 = 20.9%), at low (LA; FiO2 = 16.8%) and high (HA; FiO2 = 13.3%) normobaric hypoxia (simulated altitudes of ~1800 m and ~3600 m, respectively). Explosive (~1 s; "fast" instruction) and maximal (~5 s; "hard" instruction) voluntary isometric contractions (MVC) of the knee extensors (KE), with concurrent electromyographic (EMG) activity recordings of the vastus lateralis (VL) and rectus femoris (RF) muscles, were performed before and 1-min post-exercise. Rate of torque development (RTD) and EMG (i.e., Root Mean Square or RMS) rise from 0 to 30, -50, -100, and -200 ms were recorded, and were also normalized to maximal torque and EMG values, respectively. Distance covered during the first 5-s sprint was similar (P > 0.05) in all conditions. A larger (P < 0.05) sprint decrement score and a shorter (P < 0.05) cumulated distance covered over the eight sprints occurred in HA (-8 ± 4% and 178 ± 11 m) but not in LA (-7 ± 3% and 181 ± 10 m) compared to NM (-5 ± 2% and 183 ± 9 m). Compared to NM (-9 ± 7%), a larger (P < 0.05) reduction in MVC torque occurred post-exercise in HA (-14 ± 9%) but not in LA (-12 ± 7%), with no difference between NM and LA (P > 0.05). Irrespectively of condition (P > 0.05), peak RTD (-6 ± 11%; P < 0.05), and normalized peak RMS activity for VL (-8 ± 11%; P = 0.07) and RF (-14 ± 11%; P < 0.01) muscles were reduced post-exercise, whereas reductions (P < 0.05) in absolute RTD occurred within the 0-100 (-8 ± 9%) and 0-200 ms (-10 ± 8%) epochs after contraction onset. After normalization to MVC torque, there was no difference in RTD values. Additionally, the EMG rise for VL muscle was similar

  19. High Altitude Increases Alteration in Maximal Torque but Not in Rapid Torque Development in Knee Extensors after Repeated Treadmill Sprinting

    PubMed Central

    Girard, Olivier; Brocherie, Franck; Millet, Grégoire P.

    2016-01-01

    We assessed knee extensor neuromuscular adjustments following repeated treadmill sprints in different normobaric hypoxia conditions, with special reference to rapid muscle torque production capacity. Thirteen team- and racquet-sport athletes undertook 8 × 5-s “all-out” sprints (passive recovery = 25 s) on a non-motorized treadmill in normoxia (NM; FiO2 = 20.9%), at low (LA; FiO2 = 16.8%) and high (HA; FiO2 = 13.3%) normobaric hypoxia (simulated altitudes of ~1800 m and ~3600 m, respectively). Explosive (~1 s; “fast” instruction) and maximal (~5 s; “hard” instruction) voluntary isometric contractions (MVC) of the knee extensors (KE), with concurrent electromyographic (EMG) activity recordings of the vastus lateralis (VL) and rectus femoris (RF) muscles, were performed before and 1-min post-exercise. Rate of torque development (RTD) and EMG (i.e., Root Mean Square or RMS) rise from 0 to 30, −50, −100, and −200 ms were recorded, and were also normalized to maximal torque and EMG values, respectively. Distance covered during the first 5-s sprint was similar (P > 0.05) in all conditions. A larger (P < 0.05) sprint decrement score and a shorter (P < 0.05) cumulated distance covered over the eight sprints occurred in HA (−8 ± 4% and 178 ± 11 m) but not in LA (−7 ± 3% and 181 ± 10 m) compared to NM (−5 ± 2% and 183 ± 9 m). Compared to NM (−9 ± 7%), a larger (P < 0.05) reduction in MVC torque occurred post-exercise in HA (−14 ± 9%) but not in LA (-12 ± 7%), with no difference between NM and LA (P > 0.05). Irrespectively of condition (P > 0.05), peak RTD (−6 ± 11%; P < 0.05), and normalized peak RMS activity for VL (−8 ± 11%; P = 0.07) and RF (−14 ± 11%; P < 0.01) muscles were reduced post-exercise, whereas reductions (P < 0.05) in absolute RTD occurred within the 0–100 (−8 ± 9%) and 0–200 ms (−10 ± 8%) epochs after contraction onset. After normalization to MVC torque, there was no difference in RTD values

  20. VizieR Online Data Catalog: Stellar parameters for CoRoT exoplanet field stars (Cortes+, 2015)

    NASA Astrophysics Data System (ADS)

    Cortes, C.; Maciel, S. C.; Vieira, S.; Ferreira Lopes, C. E.; Leao, I. C.; de Oliveira, G. P.; Correia, C.; Canto Martins, B. L.; Catelan, M.; de Medeiros, J. R.

    2016-08-01

    The present stellar sample is composed of 138 stars of spectral types F, G, and K, with visual magnitudes V between 10 to 14, located in two exoplanet fields observed by CoRoT, namely the Galactic center (LRc01: Long Run Center 01) and the Galactic anticenter (LRa01: Long Run Anticenter 01) fields. (4 data files).

  1. Finest light curve details, physical parameters, and period fluctuations of CoRoT RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Benkő, J. M.; Szabó, R.; Derekas, A.; Sódor, Á.

    2016-08-01

    The CoRoT satellite supplied the scientific community with a huge data base of variable stars. Among them the RR Lyrae stars have intensively been discussed in numerous papers in the last few years, but the latest runs have not been checked to find RR Lyrae stars up to now. Our main goal was to fill this gap and complete the CoRoT RR Lyrae sample. We found nine unstudied RR Lyrae stars. Seven of them are new discoveries. We identified three new Blazhko stars. The Blazhko effect shows non-strictly repetitive nature for all stars. The frequency spectrum of the Blazhko star CoRoT 104948132 contains second overtone frequency with the highest known period ratio. The harmonic amplitude and phase declines with the harmonic order were studied for non-Blazhko stars. We found a period dependent but similar shape amplitude decline for all stars. We discovered significant random period fluctuation for one of the two oversampled target, CM Ori. After a successful transformation of the CoRoT band parameters to the Johnson V values we estimated the basic physical properties such as mass, luminosity, metallicity. The sample can be divided into two subgroups with respect to the metallicity but otherwise the physical parameters are in the canonical range of RR Lyrae stars.

  2. Fundamental properties of Kepler and CoRoT targets - III. Tuning scaling relations using the first adiabatic exponent

    NASA Astrophysics Data System (ADS)

    Yıldız, M.; Çelik Orhan, Z.; Kayhan, C.

    2016-10-01

    So-called scaling relations based on oscillation frequencies have the potential to reveal the mass and radius of solar-like oscillating stars. In the derivation of these relations, it is assumed that the first adiabatic exponent at the surface (Γ_{1s}) of such stars is constant. However, by constructing interior models for the mass range 0.8-1.6 M⊙, we show that Γ _{1s} is not constant at stellar surfaces for the effective temperature range with which we deal. Furthermore, the well-known relation between large separation and mean density also depends on Γ _{1s}. Such knowledge is the basis for our aim of modifying the scaling relations. There are significant differences between masses and radii found from modified and conventional scaling relations. However, a comparison of predictions of these relations with the non-asteroseismic observations of Procyon A reveals that new scaling relations are effective in determining the mass and radius of stars. In the present study, solar-like oscillation frequencies of 89 target stars (mostly Kepler and CoRoT) were analysed. As well as two new reference frequencies (νmin1 and νmin2) found in the spacing of solar-like oscillation frequencies of stellar interior models, we also take into account νmin0. In addition to the frequency of maximum amplitude, these frequencies have a very strong diagnostic potential in the determination of fundamental properties. The present study applies the derived relations from the models to the solar-like oscillating stars, and computes their effective temperatures using purely asteroseismic methods. There are in general very close agreements between effective temperatures from asteroseismic and non-asteroseismic (spectral and photometric) methods. For the Sun and Procyon A, for example, the agreement is almost total.

  3. Accretion dynamics and disk evolution in NGC 2264: a study based on CoRoT photometric observations

    NASA Astrophysics Data System (ADS)

    Alencar, S. H. P.; Teixeira, P. S.; Guimarães, M. M.; McGinnis, P. T.; Gameiro, J. F.; Bouvier, J.; Aigrain, S.; Flaccomio, E.; Favata, F.

    2010-09-01

    Context. The young cluster NGC 2264 was observed with the CoRoT satellite for 23 days uninterruptedly in March 2008 with unprecedented photometric accuracy. We present the first results of our analysis of the accreting population belonging to the cluster as observed by CoRoT. Aims: We search for possible light curve variability of the same nature as that observed in the classical T Tauri star AA Tau, which was attributed to a magnetically controlled inner disk warp. The inner warp dynamics is supposed to be directly associated with the interaction between the stellar magnetic field and the inner disk region. Methods: We analyzed the CoRoT light curves of 83 previously known classical T Tauri stars that belong to NGC 2264 classifying them according to their light-curve morphology. We also studied the CoRoT light-curve morphology as a function of a Spitzer-based classification of the star-disk systems. Results: The classification derived on the basis of the CoRoT light-curve morphology agrees very well with the Spitzer IRAC-based classification of the systems. The percentage of AA Tau-like light curves decreases as the inner disk dissipates, from 40% ± 10% in systems with thick inner disks to 36% ± 16% in systems with anemic disks and zero in naked photosphere systems. Indeed, 91% ± 29% of the CTTS with naked photospheres exhibit pure spot-like variability, while only 18% ± 7% of the thick disk systems do so, presumably those seen at low inclination and thus free of variable obscuration. Conclusions: AA Tau-like light curves are found to be fairly common, with a frequency of at least ~30 to 40% in young stars with inner dusty disks. The temporal evolution of the light curves indicates that the structure of the inner disk warp, located close to the corotation radius and responsible for the obscuration episodes, varies over a timescale of a few (~1-3) rotational periods. This probably reflects the highly dynamical nature of the star-disk magnetospheric interaction

  4. Nonambipolarity, orthogonal conductivity, poloidal flow, and torque

    SciTech Connect

    Hulbert, G.W.; Perkins, F.W.

    1989-02-01

    Nonambipolar processes, such as neutral injection onto trapped orbits or ripple-diffusion loss of ..cap alpha..-particles, act to charge a plasma. A current j/sub r/ across magnetic surfaces must arise in the bulk plasma to maintain charge neutrality. An axisymmetric, neoclassical model of the bulk plasma shows that these currents are carried by the ions and exert a j/sub r/B/sub theta/R/c torque in the toroidal direction. A driven poloidal flow V/sub theta/ = E/sub r/'c/B must also develop. The average current density is related to the radial electric field E/sub r/' = E/sub r/ + v/sub /phi//B/sub theta//c in a frame moving with the plasma via the orthogonal conductivity = sigma/sub /perpendicular//E/sub r/', which has the value sigma/sub /perpendicular// = (1.65epsilon/sup 1/2/)(ne/sup 2/..nu../sub ii//M..cap omega../sub theta//sup 2/) in the banana regime. If an ignited plasma loses an appreciable fraction ..delta.. of its thermonuclear ..cap alpha..-particles by banana ripple diffusion, then the torque will spin the plasma to sonic rotation in a time /tau//sub s/ approx. 2/tau//sub E//..delta.., /tau//sub E/ being the energy confinement time. 10 refs., 1 fig.

  5. Electromagnetic force and torque in ponderable media.

    PubMed

    Mansuripur, Masud

    2008-09-15

    Maxwell's macroscopic equations combined with a generalized form of the Lorentz law of force are a complete and consistent set of equations. Not only are these five equations fully compatible with special relativity, they also conform with conservation laws of energy, momentum, and angular momentum. We demonstrate consistency with the conservation laws by showing that, when a beam of light enters a magnetic dielectric, a fraction of the incident linear (or angular) momentum pours into the medium at a rate determined by the Abraham momentum density, E x H/c(2), and the group velocity V(g) of the electromagnetic field. The balance of the incident, reflected, and transmitted momenta is subsequently transferred to the medium as force (or torque) at the leading edge of the beam, which propagates through the medium with velocity V(g). Our analysis does not require "hidden" momenta to comply with the conservation laws, nor does it dissolve into ambiguities with regard to the nature of electromagnetic momentum in ponderable media. The linear and angular momenta of the electromagnetic field are clearly associated with the Abraham momentum, and the phase and group refractive indices (n(p) and n(g)) play distinct yet definitive roles in the expressions of force, torque, and momentum densities. PMID:18795019

  6. Torque generation mechanism of ATP synthase

    NASA Astrophysics Data System (ADS)

    Miller, John; Maric, Sladjana; Scoppa, M.; Cheung, M.

    2010-03-01

    ATP synthase is a rotary motor that produces adenosine triphosphate (ATP), the chemical currency of life. Our proposed electric field driven torque (EFT) model of FoF1-ATP synthase describes how torque, which scales with the number of c-ring proton binding sites, is generated by the proton motive force (pmf) across the mitochondrial inner membrane. When Fo is coupled to F1, the model predicts a critical pmf to drive ATP production. In order to fully understand how the electric field resulting from the pmf drives the c-ring to rotate, it is important to examine the charge distributions in the protonated c-ring and a-subunit containing the proton channels. Our calculations use a self-consistent field approach based on a refinement of reported structural data. The results reveal changes in pKa for key residues on the a-subunit and c-ring, as well as titration curves and protonation state energy diagrams. Health implications will be briefly discussed.

  7. The solar-like CoRoT target HD 170987: spectroscopic and seismic observations

    NASA Astrophysics Data System (ADS)

    Mathur, S.; García, R. A.; Catala, C.; Bruntt, H.; Mosser, B.; Appourchaux, T.; Ballot, J.; Creevey, O. L.; Gaulme, P.; Hekker, S.; Huber, D.; Karoff, C.; Piau, L.; Régulo, C.; Roxburgh, I. W.; Salabert, D.; Verner, G. A.; Auvergne, M.; Baglin, A.; Chaplin, W. J.; Elsworth, Y.; Michel, E.; Samadi, R.; Sato, K.; Stello, D.

    2010-07-01

    Context. The CoRoT mission is in its third year of observation and the data from the second long run in the galactic centre direction are being analysed. The solar-like oscillating stars that have been observed up to now have given some interesting results, specially concerning the amplitudes that are lower than predicted. We present here the results from the analysis of the star HD 170987. Aims: The goal of this research work is to characterise the global parameters of HD 170987. We look for global seismic parameters such as the mean large separation, maximum amplitude of the modes, and surface rotation because the signal-to-noise ratio in the observations does not allow us to measure individual modes. We also aim to retrieve the parameters of the star and its chemical composition. Methods: We studied the chemical composition of the star through ground-based observations performed with the NARVAL spectrograph. We used several methods to calculate the global parameters from the acoustic oscillations based on CoRoT data. The light curve of the star has been interpolated with inpainting algorithms to reduce the effect of data gaps. Results: We found the power excess related to p modes in the range [400-1200] μHz with a mean large separation of 55.2 ± 0.8 μHz with a probability above 95 % that increases to 55.9 ± 0.2 μHz in a higher frequency range [500-1250] μHz and a rejection level of 1%. A hint of the variation of this quantity with frequency was also found. The rotation period of the star is estimated to be around 4.3 days with an inclination axis of i = 50° +20-13. We measured a bolometric amplitude per radial mode in a range [2.4-2.9] ppm around 1000 μHz. Finally we estimate the stellar mass with a grid of models, M = 1.43 ± 0.05 M_⊙, the radius, R = 1.96 ± 0.046 R_⊙, and the age ~2.4 Gyr. The CoRoT space mission, launched on 2006 December 27, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD

  8. Periodicity search as a tool for disentangling the contaminated colour light curve of CoRoT 102781750

    NASA Astrophysics Data System (ADS)

    Paparó, M.; Chadid, M.; Chapellier, E.; Benkő, J. M.; Szabó, R.; Kolenberg, K.; Guggenberger, E.; Regály, Zs.; Auvergne, M.; Baglin, A.; Weiss, W. W.

    2011-07-01

    Context. The CoRoT space mission (COnvection, ROtation and planetary Transits) launched in December 2006, aims at finding transiting exoplanets and investigating stellar oscillation in adjacent stellar fields, called exo- and seismofields, respectively. Besides the seismofields, CoRoT has a strong potential for seismological research on the exofields. Up to now, only a limited number of RR Lyrae stars have been classified among the CoRoT targets. Knowing the astrophysical importance of the RR Lyrae stars, we attempted to get useful information even from a contaminated light curve of a possible RR Lyrae pulsator. Aims: The star CoRoT 102781750 reveals a puzzle, showing a very complex and altering variation in different "CoRoT colours". We established without doubt that more than a single star was situated within the CoRoT mask. Using a search for periodicity as a tool, our aim is to disentangle the composite light curve and identify the type of sources behind the variability. Methods: Both flux and magnitude light curves were used. Conversion was applied after a jump- and trend-filtering algorithm. We applied different types of period-finding techniques including MuFrAn and Period04. Results: The amplitude and phase peculiarities obtained from the independent analysis of CoRoT r, g, and b colours and ground-based follow-up photometric observations ruled out the possibility of either a background monoperiodic or a Blazhko type RR Lyrae star being in the mask. The main target, an active star, shows at least two spotted areas that reveal a Prot = 8.8 h (f0 = 2.735 c d-1) mean rotation period. The evolution of the active regions helped to derive a period change of dP/dt = 1.6 × 10-6 (18 s over the run) and a differential rotation of α = ΔΩ/Ω = 0.0074. The 0.015m linear decrease and a local 0.005m increase in the dominant period's amplitude are interpreted as a decay of the old spotted region and an appearance of a new one, respectively. A star that is detected only

  9. Investigation and Improvement of Torque Response of Control System Based on Direct Torque Control in Interior Permanent Magnet Synchronous Motors

    NASA Astrophysics Data System (ADS)

    Inoue, Yukinori; Morimoto, Shigeo; Sanada, Masayuki

    In this study, we investigate the torque response of a control system that is based on the direct torque control (DTC) principle for an interior permanent magnet synchronous motor (IPMSM). We also propose a gain-scheduling method for improving the torque response. Reference flux vector calculation (RFVC) DTC is used in this study. In RFVC DTC, a PI controller is used for torque control; this is in contrast to the use of the hysteresis comparator and switching table in basic DTC. In this paper, we present the relationship between the torque response and the gain of the PI controller. This relationship is derived by using the transfer function of the torque control loop. In this study, we also examine the difference between the torque responses of two motors that have different machine parameters. The proposed method can be used to realize a torque response that is independent of the operating torque. The simulation results and experimental results presented in this paper show the validity of the derived relationship as well as the effectiveness of the proposed method.

  10. The evolution of corotating stream fronts near the ecliptic plane in the inner solar system, 1. Two-dimensional fronts

    SciTech Connect

    Pizzo, V.J. )

    1989-07-01

    Numerical models of corotating solar wind flows have enjoyed considerable success in simulating the evolution of shocks and corotating interaction regions (CIRs) in the region beyond 1 AU, but their performance with respect to stream fronts located nearer the Sun has been somewhat disappointing. In particular, they tend to predict erroneously that corotating shock pairs should occur relatively frequently within 1 AU, given the sort of sharp boundaries between slow and fast flows observed at stream fronts near 0.3 AU by Helios. We use an existing two-dimensional MHD numerical model for corotating flow in the supersonic, superalfvenic solar wind to show that the predictions of premature shock pair formation are due to improper specification of flow conditions on the initial surface (inner boundary) used as the starting point in such models. This faulty initialization leads to the generation of a physically extraneous strong compression along the stream interface just outside the initial surface, which results in the appearance of evolutionary artifacts (like spurious discontinuities) further on in the solution. We describe an initialization scheme incorporating flow conditions more appropriate to stream fronts near the Sun and demonstrate that it produces the smooth initial behavior expected on physical grounds. Thus free of the evolutionary artifacts, we see that the shear flow at the stream interface approximately balances the kinematic steepening near the Sun, which for typical input conditions keeps the corotating shock pair from forming before about 1.5 AU. We describe the criteria for shock formation in terms of the interface dynamics and show that the steepening process cannot be treated even approximately with conventional kinematic techniques. In a subsequent paper we investigate how the three-dimensional geometry of the stream front affects the dynamical evolution and the resulting CIR structure.

  11. An examination of ankle, knee, and hip torque production in individuals with chronic ankle instability.

    PubMed

    Gribble, Phillip A; Robinson, Richard H

    2009-03-01

    There is some debate in the literature as to whether strength deficits exist at the ankle in individuals with chronic ankle instability (CAI). Additionally, there is evidence to suggest that knee and hip performance is altered in those with CAI. Therefore, the purpose of this study was to determine whether CAI is associated with deficits in ankle, knee, and hip torque. Fifteen subjects with unilateral CAI and fifteen subjects with healthy ankles participated. Subjects reported to the laboratory for one session during which the torque production of ankle plantar flexion/dorsiflexion, knee flexion/extension, and hip flexion/extension were measured with an isokinetic device. Subjects performed 5 maximum-effort repetitions of a concentric/concentric protocol at 60 degrees .s for both extremities. Average peak torque (APT) values were calculated. The subjects with CAI demonstrated significantly less APT production for knee flexion (F1,28 = 5.40; p = 0.03) and extension (F1,28 = 5.34; p = 0.03). Subjects with CAI exhibited significantly less APT for ankle plantar flexion in the injured limb compared with their noninjured limb (F1,28 = 6.51; p = 0.02). No significant difference in ankle dorsiflexion or hip flexion/extension APT production existed between the 2 groups. Individuals with CAI, in addition to deficits in ankle plantar flexion torque, had deficits in knee flexor and extensor torque, suggesting that distal joint instability may lead to knee joint neuromuscular adaptations. There were no similar deficits at the hip. Future research should determine what implications this has for prevention and rehabilitation of lower-extremity injury. Clinicians may need to consider including rehabilitation efforts to address these deficits when rehabilitating patients with CAI.

  12. Intramuscular pressure and torque during isometric, concentric and eccentric muscular activity

    NASA Technical Reports Server (NTRS)

    Styf, J.; Ballard, R.; Aratow, M.; Crenshaw, A.; Watenpaugh, D.; Hargens, A. R.

    1995-01-01

    Intramuscular pressures, electromyography (EMG) and torque generation during isometric, concentric and eccentric maximal isokinetic muscle activity were recorded in 10 healthy volunteers. Pressure and EMG activity were continuously and simultaneously measured side by side in the tibialis anterior and soleus muscles. Ankle joint torque and position were monitored continuously by an isokinetic dynamometer during plantar flexion and dorsiflexion of the foot. The increased force generation during eccentric muscular activity, compared with other muscular activity, was not accompanied by higher intramuscular pressure. Thus, this study demonstrated that eccentric muscular activity generated higher torque values for each increment of intramuscular pressure. Intramuscular pressures during antagonistic co-activation were significantly higher in the tibilis anterior muscle (42-46% of maximal agonistic activity) compared with the soleus muscle (12-29% of maximal agonistic activity) and was largely due to active recruitment of muscle fibers. In summary, eccentric muscular activity creates higher torque values with no additional increase of the intramuscular pressure compared with concentric and isometric muscular activity.

  13. Stress Analysis of a New Disk-Type Variable Torque Slipping Clutch with Skewed Rollers

    NASA Astrophysics Data System (ADS)

    Feng, Ming; Ono, Kyosuke; Mimura, Kenji

    In this paper a new disk type of the variable torque slipping clutch with skewed rollers (VTSCSR) is presented and investigated both theoretically and experimentally. It is comprised of two flat disks, a number of skewed cylindrical rollers, and a cage. The slipping torque is produced by the skewed rollers rolling and slipping between the two disks. Based on the integral equation of the Boussinesq solution, the contact pressures are numerically calculated under the condition that the nonlinear equilibrium equations of the clutch elements are satisfied. By considering both pressure and friction, the components of subsurface stress are calculated from the integration of the Mindlin's subsurface stress equations of concentrated force. A numerical solver is then successfully developed by which the characteristics of the disk-type VTSCSR, including the torque capacity, angular velocities of the roller and cage, contact pressure and von Mises stress, etc, are calculated and illustrated for the typical designs. The influences on the distribution of the von Mises stress by applying various types of profiled rollers to the disk-type VTSCSR are also discussed. It has been found that the full crown with two arcs profiled roller can approximately give rise to the axially uniform distribution of the von Mises stress and therefore satisfies the design principle of the average damage of materials. In addition, the preliminary experiment was done in order to show the feasibility of this design idea and to verify the theoretical torque capacity.

  14. Characteristics of a multilayer one-touch-point ultrasonic motor for high torque

    NASA Astrophysics Data System (ADS)

    Jeong, Seong-Su; Park, Tae-Gone; Park, Jong-Kyu

    2013-04-01

    In this paper, a one-touch-point ultrasonic motor is proposed. Fabricating the stator is easy because of its simple structure and the use of a punching technique. Also, a thin stator is advantageous to use in tight spaces. A thin metal plate was used as a V-shaped stator and two to the upper and two to the lower ceramic plates were attached to the upper and the lower surfaces respectively of the metal plate. When two sinusoidal sources with a phase difference of 90 degrees were applied to the stator, an elliptical displacement was generated at contact tip of the stator. Modeling of the ultrasonic motor was done and the displacement characteristics were defined by using a finite element analysis program (ATILA). To improve the speed and the torque of the ultrasonic motor, we analyzed the effects of the leg angle and the number of ceramic layers. In addition, a model with large x-axis and y-axis displacements was fabricated, and the speed and the torque were measured under various conditions. The elliptical motion of the contact tip of the stator was consistently obtained at the resonance frequency. The maximum speed and torque were obtained by using maximum elliptical displacement model. The speed and the torque increased linearly with increasing voltage.

  15. EDITORIAL: Spin-transfer-torque-induced phenomena Spin-transfer-torque-induced phenomena

    NASA Astrophysics Data System (ADS)

    Hirohata, Atsufumi

    2011-09-01

    This cluster, consisting of five invited articles on spin-transfer torque, offers the very first review covering both magnetization reversal and domain-wall displacement induced by a spin-polarized current. Since the first theoretical proposal on spin-transfer torque—reported by Berger and Slonczewski independently—spin-transfer torque has been experimentally demonstrated in both vertical magnetoresistive nano-pillars and lateral ferromagnetic nano-wires. In the former structures, an electrical current flowing vertically in the nano-pillar exerts spin torque onto the thinner ferromagnetic layer and reverses its magnetization, i.e., current-induced magnetization switching. In the latter structures, an electrical current flowing laterally in the nano-wire exerts torque onto a domain wall and moves its position by rotating local magnetic moments within the wall, i.e., domain wall displacement. Even though both phenomena are induced by spin-transfer torque, each phenomenon has been investigated separately. In order to understand the physical meaning of spin torque in a broader context, this cluster overviews both cases from theoretical modellings to experimental demonstrations. The earlier articles in this cluster focus on current-induced magnetization switching. The magnetization dynamics during the reversal has been calculated by Kim et al using the conventional Landau--Lifshitz-Gilbert (LLG) equation, adding a spin-torque term. This model can explain the dynamics in both spin-valves and magnetic tunnel junctions in a nano-pillar form. This phenomenon has been experimentally measured in these junctions consisting of conventional ferromagnets. In the following experimental part, the nano-pillar junctions with perpendicularly magnetized FePt and half-metallic Heusler alloys are discussed from the viewpoint of efficient magnetization reversal due to a high degree of spin polarization of the current induced by the intrinsic nature of these alloys. Such switching can

  16. Mirroring of fast solar flare electrons on a downstream corotating interaction region

    NASA Technical Reports Server (NTRS)

    Anderson, K. A.; Sommers, J.; Lin, R. P.; Pick, M.; Chaizy, P.; Murphy, N.; Smith, E. J.; Phillips, J. L.

    1995-01-01

    We discuss an example of confinement of fast solar electrons by a discrete solar wind-interplanetary magnetic field structure on February 22, 1991. The structure is about 190,000 km in width and is clearly defined by changes in the direction of the magnetic field at the Ulysses spacecraft. This structure carries electrons moving toward the Sun as well as away from the Sun. A loss cone in the angular distribution of the fast electrons shows that mirroring, presumably magnetic, takes place downstream from the spacecraft. Following passage of this narrow structure, the return flux vanishes for 21 min after which time the mirroring resumes and persists for several hours. We identify the enhanced magnetic field region lying downstream from the Ulysses spacecraft that is responsible for the mirroring to be a corotating stream interaction region. Backstreaming suprathermal electron measurements by the Los Alamos National Laboratory plasma experiment on the Ulysses spacecraft support this interpretation.

  17. Looking for planetary candidates in the CoRoT Long Run LRc10

    NASA Astrophysics Data System (ADS)

    Zannoni, A.; Borsa, F.; Poretti, E.; Lodato, G.; Rainer, M.; Frustagli, G.

    We analysed the public data of the CoRoT Long Run LRc10 looking for planetary candidates. In a first step we removed outliers and trends caused by stellar activity and instrumental problems. Then we applied the Box-fitting Least Squares (BLS) algorithm to detect periodic decreases in luminosity. From all the significative transit detections, we selected the ones that passed different checks. For the 7 planetary candidates found, we applied a new ``ad hoc'' normalization and fitted the orbital parameters, to verify their reliability. Using the stellar temperature information, we could estimate the dimensions that the candidates should have if confirmed. Our research method demonstrated to be sensitive to candidates with hypothetic dimension up to ˜3.5 REarth on stars of mag V≃14.

  18. A three-dimensional model of corotating streams in the solar wind. 1: Theoretical foundations

    NASA Technical Reports Server (NTRS)

    Pizzo, V. J.

    1978-01-01

    The theoretical and mathematical background pertinent to the study of steady, corotating solar wind structure in all three spatial dimensions (3-D) is discussed. The dynamical evolution of the plasma in interplanetary space (defined as the region beyond roughly 35 solar radii where the flow is supersonic) is approximately described by the nonlinear, single fluid, polytropic (magneto-) hydrodynamic equations. Efficient numerical techniques for solving this complex system of coupled, hyperbolic partial differential equations are outlined. The formulation is inviscid and nonmagnetic, but methods allow for the potential inclusion of both features with only modest modifications. One simple, highly idealized, hydrodynamic model stream is examined to illustrate the fundamental processes involved in the 3-D dynamics of stream evolution. Spatial variations in the rotational stream interaction mechanism were found to produce small nonradial flows on a global scale that lead to the transport of mass, energy, and momentum away from regions of relative compression and into regions of relative rarefaction.

  19. Stellar rotation at young ages: new results from Corot's monitoring NGC 2264

    NASA Astrophysics Data System (ADS)

    Favata, F.; Micela, G.; Alencar, S.; Aigrain, S.; Zwintz, K.

    2010-11-01

    Stellar rotation at young ages: new results from Corot's Angular momentum is one of the driving forces in the early evolution of stars. Issues such as the coupling between the star and the accretion disk (the so-called disk regulation paradigm), are traced by the evolution of rotational momentum, but affect the star-forming process as a whole. One of the features observed in star-forming regions (e.g. ONC and NGC 2264) of age between 1 and few Myr, for masses above 0.25 solar masses, is a bimodality of the rotational period distribution, with a peak around 1 day and the other at around 4 to 7 days. This bimodality has been interpreted as the smoking gun of the disk-locking mechanism (with the fast rotators having lost their disk and the slow ones still being regulated by their disks).

  20. CoRoT reveals a magnetic activity cycle in a Sun-like star.

    PubMed

    García, Rafael A; Mathur, Savita; Salabert, David; Ballot, Jérôme; Régulo, Clara; Metcalfe, Travis S; Baglin, Annie

    2010-08-27

    The 11-year activity cycle of the Sun is a consequence of a dynamo process occurring beneath its surface. We analyzed photometric data obtained by the CoRoT space mission, showing solarlike oscillations in the star HD49933, for signatures of stellar magnetic activity. Asteroseismic measurements of global changes in the oscillation frequencies and mode amplitudes reveal a modulation of at least 120 days, with the minimum frequency shift corresponding to maximum amplitude as in the Sun. These observations are evidence of a stellar magnetic activity cycle taking place beneath the surface of HD49933 and provide constraints for stellar dynamo models under conditions different from those of the Sun. PMID:20798310

  1. Comparison of False Alarm Rejection Methods used in CoRoT Blind Test 2

    NASA Astrophysics Data System (ADS)

    Almenara, J. M.; Deeg, H. J.; Régulo, C.; Alonso, R.

    2007-07-01

    Transit searches provide a large number of planet candidates. Before attempting follow-up observations, the best effort should be spent in classifying the light-curves, rejecting false alarms and selecting the most likely ones for real planets. A number of analysis tools has been developed with these objectives. Here, we apply such tools to 237 simulated multi-color light-curves from CoRoT Blind Test 2, which contain simulated planet transits and several configurations of impostors. Their comparison gives indications of the various tools' classification and false-alarm rejection capabilities. In order to arrive at the candidate identifications, we used an automated scheme of weighted punctuations assigned to the individual tests, which avoids that results from a single test dominate a candidate's classification.

  2. Asteroseismic Analysis of the CoRoT Target HD 169392

    NASA Astrophysics Data System (ADS)

    Mathur, S.; Bruntt, H.; Catala, C.; Benomar, O.; Davies, G. R.; García, R. A.; Salabert, D.; Ballot, J.; Mosser, B.; Régulo, C.; Chaplin, W. J.; Elsworth, Y.; Handberg, R.; Hekker, S.; Mantegazza, L.; Michel, E.; Poretti, E.; Rainer, M.; Roxburgh, I. W.; Samadi, R.; Steslicki, M.; Uytterhoeven, K.; Verner, G. A.; Auvergne, M.; Baglin, A.; Barceló Forteza, S.; Baudin, F.; Roca Cortés, T.

    2013-12-01

    The satellite CoRoT (Convection, Rotation, and planetary Transits) has provided high-quality data for almost six years. We show here the asteroseismic analysis and modeling of HD 169392A, which belongs to a weakly-bound binary system as the distance between the two components is ˜4250 au. The main component, HD 169392A, is a G0 IV star with a magnitude of 7.50 while the second component is a G0 V - G2 IV star with a magnitude of 8.98. This analysis focuses on the main component, as the secondary is too faint for the measurement of seismic parameters. A complete modeling has been possible thanks to complementary spectroscopic observations from HARPS (High Accuracy Radial Velocity Planet Searcher), providing Teff = 5985 ± 60 K, log g = 3.96 ± 0.07, and [Fe/H] = -0.04 ± 0.10.

  3. Shock acceleration of energetic particles in corotating interaction regions in the solar wind

    SciTech Connect

    Fisk, L.A.; Lee, M.A.

    1980-04-15

    A simple shock model for the acceleration of energetic particles in corotating interaction regions (CIRs) in the solar wind is presented. Particles are accelerated at the forward and reverse shocks which bound the CIR by being compressed between the shock fronts and magnetic irregularities upstream from the shocks, or by being compressed between upstream irregularities and those downstream from the shocks. Particles also suffer adiabatic deceleration in the expanding solar wind, an effect not included in previous shock models for acceleration in CIRs. The model is able to account for the observed exponential spectra at Earth, the observed behavior of the spectra with radial distance, the observed radial gradients in the intensity, and the observed differences in the intensity and spectra at the forward and reverse shocks.

  4. Mirroring of fast solar flare electrons on a downstream corotating interaction region

    SciTech Connect

    Anderson, K.A.; Sommers, J.; Lin, R.P.; Pick, M.; Chaizy, P.; Murphy, N.; Smith, E.J.; Phillips, J.L.

    1995-01-01

    The authors discuss an example of confinement of fast solar electrons by a discrete solar wind-interplanetary magnetic field structure on February 22, 1991. The structure is about 190,000 km in width and is clearly defined by changes in the direction of the magnetic field at the Ulysses spacecraft. This structure carries electrons moving toward the Sun as well as away from the Sun. A loss cone in the angular distribution of the fast electrons shows that mirroring, presumably magnetic, takes place downstream from the spacecraft. Following passage of this narrow structure, the return flux vanishes for 21 min after which time the mirroring resumes and persists for several hours. The authors identify the enhanced magnetic field region lying downstream from the Ulysses spacecraft that is responsible for the mirroring to be a corotating stream interaction region. Backstreaming suprathermal electron measurements by the Los Alamos National Laboratory plasma experiment on the Ulysses spacecraft support this interpretation. 12 refs., 9 figs.

  5. The Berlin Exoplanet Search Telescope II Catalog of Variable Stars. II. Characterization of the CoRoT SRc02 Field

    NASA Astrophysics Data System (ADS)

    Klagyivik, P.; Csizmadia, Sz.; Pasternacki, T.; Cabrera, J.; Chini, R.; Eigmüller, P.; Erikson, A.; Fruth, T.; Kabath, P.; Lemke, R.; Murphy, M.; Rauer, H.; Titz-Weider, R.

    2016-05-01

    Time-series photometry of the CoRoT field SRc02 was obtained by the Berlin Exoplanet Search Telescope II (BEST II) in 2009. The main aim was to conduct a ground-based follow-up of the CoRoT field in order to detect variable stars with better spatial resolution than what can be achieved with the CoRoT Space Telescope. A total of 1846 variable stars were detected, of which only 30 have been previously known. For nine eclipsing binaries the stellar parameters were determined by modeling their light curves.

  6. The CoRoT chemical peculiar target star HD 49310

    NASA Astrophysics Data System (ADS)

    Paunzen, E.; Fröhlich, H.-E.; Netopil, M.; Weiss, W. W.; Lüftinger, T.

    2015-02-01

    Context. The magnetic chemically peculiar (CP) stars of the upper main sequence are well-suited laboratories for investigating the influence of local magnetic fields on the stellar surface because they produce inhomogeneities (spots) that can be investigated in detail as the star rotates. Aims: We studied the inhomogeneous surface structure of the CP2 star HD 49310 based on high-quality CoRoT photometry obtained during 25 days. The data have nearly no gaps. This analysis is similar to a spectroscopic Doppler-imaging analysis, but it is not a tomographic method. Methods: We performed detailed light-curve fitting in terms of stationary circular bright spots. Furthermore, we derived astrophysical parameters with which we located HD 49310 within the Hertzsprung-Russell diagram. We also investigated the possible connection of this star to the nearby young open cluster NGC 2264. Results: With a Bayesian technique, we produced a surface map that shows six bright spots. After removing some artefacts, the residuals of the observed and synthetic photometric data are ± 0.123 mmag. The rotational period of the star is P = 1.91909 ± 0.00001 days. Our photometric observations therefore cover about 13 full rotational cycles. Three spots are very large with diameters of ≃ 40deg. The spots are brighter by 40% than the unperturbed stellar photosphere. Conclusions: HD 49310 is a classical silicon (CP2) star with a mass of about 3 M⊙. It is not a member of NGC 2264. Our analysis shows the potential of using high-quality photometric data to analyse the surface structure of CP stars. A comprehensive analysis of similar archival data, preferrably from space missions, would contribute significantly to our understanding of surface phenomena of CP stars and their temporal evolution. The CoRoT space mission was developed and is operated by the French space agency CNES, with participation of ESA's RSSD and Science Programmes, Austria, Belgium, Brazil, Germany, and Spain.

  7. Solar-like oscillations with low amplitude in the CoRoT target HD 181906

    NASA Astrophysics Data System (ADS)

    García, R. A.; Régulo, C.; Samadi, R.; Ballot, J.; Barban, C.; Benomar, O.; Chaplin, W. J.; Gaulme, P.; Appourchaux, T.; Mathur, S.; Mosser, B.; Toutain, T.; Verner, G. A.; Auvergne, M.; Baglin, A.; Baudin, F.; Boumier, P.; Bruntt, H.; Catala, C.; Deheuvels, S.; Elsworth, Y.; Jiménez-Reyes, S. J.; Michel, E.; Pérez Hernández, F.; Roxburgh, I. W.; Salabert, D.

    2009-10-01

    Context: The F8 star HD 181906 (effective temperature ˜6300 K) was observed for 156 days by the CoRoT satellite during the first long run in the direction of the galactic centre. Analysis of the data reveals a spectrum of solar-like acoustic oscillations. However, the faintness of the target (mv = 7.65) means the signal-to-noise (S/N) in the acoustic modes is quite low, and this low S/N leads to complications in the analysis. Aims: We extract global variables of the star, as well as key parameters of the p modes observed in the power spectrum of the lightcurve. Methods: The power spectrum of the lightcurve, a wavelet transform and spot fitting were used to obtain the average rotation rate of the star and its inclination angle. Then, the autocorrelation of the power spectrum and the power spectrum of the power spectrum were used to properly determine the large separation. Finally, estimations of the mode parameters were done by maximizing the likelihood of a global fit, where several modes were fit simultaneously. Results: We have been able to infer the mean surface rotation rate of the star (~4 μHz) with indications of the presence of surface differential rotation, the large separation of the p modes (~87 μHz), hence also the “ridges” corresponding to overtones of the acoustic modes. CoRoT (Convection, Rotation and planetary Transits) is a minisatellite developed by the French Space agency CNES in collaboration with the Science Programmes of ESA, Austria, Belgium, Brazil, Germany and Spain.

  8. Large Amplitude IMF Fluctuations in Corotating Interaction Regions: Ulysses at Midlatitudes

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.; Ho, Christian M.; Arballo, John K.; Goldstein, Bruce E.; Balogh, Andre

    1995-01-01

    Corotating Interaction Regions (CIRs), formed by high-speed corotating streams interacting with slow speed streams, have been examined from -20 deg to -36 deg heliolatitudes. The high-speed streams emanate from a polar coronal hole that Ulysses eventually becomes fully embedded in as it travels towards the south pole. We find that the trailing portion of the CIR, from the interface surface (IF) to the reverse shock (RS), contains both large amplitude transverse fluctuations and magnitude fluctuations. Similar fluctuations have been previously noted to exist within CIRs detected in the ecliptic plane, but their existence has not been explained. The normalized magnetic field component variances within this portion of the CIR and in the trailing high-speed stream are approximately the same, indicating that the fluctuations in the CIR are compressed Alfven waves. Mirror mode structures with lower intensities are also observed in the trailing portion of the CIR, presumably generated from a local instability driven by free energy associated with compression of the high-speed solar wind plasma. The mixture of these two modes (compressed Alfven waves and mirror modes) plus other modes generated by three wave processes (wave-shock interactions) lead to a lower Alfvenicity within the trailing portion of the CfR than in the high-speed stream proper. The results presented in this paper suggest a mechanism for generation of large amplitude B(sub z) fluctuations within CIRS. Such phenomena have been noted to be responsible for the generation of moderate geomagnetic storms during the declining phase of the solar cycle.

  9. Spin torque driven nano-spintronic devices

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaochun

    Spin momentum transfer, an effect first predicted theoretically and later observed by carefully designed experiments, has found its use in current-perpendicular-to-plane (CPP) magnetic devices over the past decade. Although extensive research on this subject has been conducted both experimentally and theoretically, the understanding of its effect and impact on the performance of actual magnetic devices with finite dimensions at nanometer scale are still far from complete. Innovations based on its utilization for novel devices application have also been rare. This thesis presents a series of systematic micromagnetic studies focusing on the spin momentum transfer effect in various CPP devices at deep submicrometer and nanometer dimensions. The thesis contributes to the subject of spin momentum transfer in two particular aspects: the insightful understanding of its impact to CPP magnetoresistive devices and its innovative utilization in novel MRAM designs. The thesis is organized as the following: Chapter 1 gives a general introduction on spin momentum transfer effect. In Chapter 2 of the thesis, the theoretical micromagnetic model and the numerical calculation methodology is presented. The work in Chapter 3, 4 and 5 is based on the micromagnetic modeling. In Chapter 3, current MRAM designs and challenges are reviewed. A new low power vertical ring shaped MRAM design and a new perpendicular MRAM are presented. The two new designs utilize both spin transfer torque and Ampere's field to switching memory states. They are free of write addressing disturbance and avoid the limit of the half selection problem in the conventional design. The magnetic performance as well as the scalability of memories is described in this chapter. Chapter 4 has investigated the magnetization oscillation excited by perpendicularly polarized spin transfer torque in CPP structure and designed its applications in microwave spin nano-oscillator and ferromagnetic resonance assisted recording

  10. 40 CFR 91.306 - Dynamometer torque cell calibration.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Dynamometer torque cell calibration... Provisions § 91.306 Dynamometer torque cell calibration. (a)(1) Any lever arm used to convert a weight or a... with the adjusted or repaired system. (b) Option. A master load-cell or transfer standard may be...

  11. 40 CFR 91.306 - Dynamometer torque cell calibration.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Dynamometer torque cell calibration... Provisions § 91.306 Dynamometer torque cell calibration. (a)(1) Any lever arm used to convert a weight or a... with the adjusted or repaired system. (b) Option. A master load-cell or transfer standard may be...

  12. 40 CFR 91.306 - Dynamometer torque cell calibration.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Dynamometer torque cell calibration... Provisions § 91.306 Dynamometer torque cell calibration. (a)(1) Any lever arm used to convert a weight or a... with the adjusted or repaired system. (b) Option. A master load-cell or transfer standard may be...

  13. 40 CFR 91.306 - Dynamometer torque cell calibration.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Dynamometer torque cell calibration... Provisions § 91.306 Dynamometer torque cell calibration. (a)(1) Any lever arm used to convert a weight or a... with the adjusted or repaired system. (b) Option. A master load-cell or transfer standard may be...

  14. 40 CFR 91.306 - Dynamometer torque cell calibration.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Dynamometer torque cell calibration. 91....306 Dynamometer torque cell calibration. (a)(1) Any lever arm used to convert a weight or a force... with the adjusted or repaired system. (b) Option. A master load-cell or transfer standard may be...

  15. 40 CFR 90.306 - Dynamometer torque cell calibration.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Dynamometer torque cell calibration. 90... Equipment Provisions § 90.306 Dynamometer torque cell calibration. (a)(1) Any lever arm used to convert a... (a)(6) of this section with the adjusted or repaired system. (b) Option. A master load-cell...

  16. 14 CFR 23.397 - Limit control forces and -torques.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Limit control forces and -torques. 23.397... Control Surface and System Loads § 23.397 Limit control forces and -torques. (a) In the control surface... exceed those that would result in flight from the application of any pilot force within the...

  17. 14 CFR 29.397 - Limit pilot forces and torques.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Limit pilot forces and torques. 29.397... System Loads § 29.397 Limit pilot forces and torques. (a) Except as provided in paragraph (b) of this section, the limit pilot forces are as follows: (1) For foot controls, 130 pounds. (2) For stick...

  18. 14 CFR 27.397 - Limit pilot forces and torques.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Limit pilot forces and torques. 27.397... System Loads § 27.397 Limit pilot forces and torques. (a) Except as provided in paragraph (b) of this section, the limit pilot forces are as follows: (1) For foot controls, 130 pounds. (2) For stick...

  19. 14 CFR 29.397 - Limit pilot forces and torques.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Limit pilot forces and torques. 29.397... System Loads § 29.397 Limit pilot forces and torques. (a) Except as provided in paragraph (b) of this section, the limit pilot forces are as follows: (1) For foot controls, 130 pounds. (2) For stick...

  20. 14 CFR 27.397 - Limit pilot forces and torques.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Limit pilot forces and torques. 27.397... System Loads § 27.397 Limit pilot forces and torques. (a) Except as provided in paragraph (b) of this section, the limit pilot forces are as follows: (1) For foot controls, 130 pounds. (2) For stick...

  1. 14 CFR 23.397 - Limit control forces and -torques.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Limit control forces and -torques. 23.397... Control Surface and System Loads § 23.397 Limit control forces and -torques. (a) In the control surface... exceed those that would result in flight from the application of any pilot force within the...

  2. 14 CFR 29.397 - Limit pilot forces and torques.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Limit pilot forces and torques. 29.397... System Loads § 29.397 Limit pilot forces and torques. (a) Except as provided in paragraph (b) of this section, the limit pilot forces are as follows: (1) For foot controls, 130 pounds. (2) For stick...

  3. 14 CFR 27.397 - Limit pilot forces and torques.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Limit pilot forces and torques. 27.397... System Loads § 27.397 Limit pilot forces and torques. (a) Except as provided in paragraph (b) of this section, the limit pilot forces are as follows: (1) For foot controls, 130 pounds. (2) For stick...

  4. 14 CFR 23.397 - Limit control forces and -torques.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Limit control forces and -torques. 23.397... Control Surface and System Loads § 23.397 Limit control forces and -torques. (a) In the control surface... exceed those that would result in flight from the application of any pilot force within the...

  5. 14 CFR 29.397 - Limit pilot forces and torques.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Limit pilot forces and torques. 29.397... System Loads § 29.397 Limit pilot forces and torques. (a) Except as provided in paragraph (b) of this section, the limit pilot forces are as follows: (1) For foot controls, 130 pounds. (2) For stick...

  6. 14 CFR 27.397 - Limit pilot forces and torques.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Limit pilot forces and torques. 27.397... System Loads § 27.397 Limit pilot forces and torques. (a) Except as provided in paragraph (b) of this section, the limit pilot forces are as follows: (1) For foot controls, 130 pounds. (2) For stick...

  7. 14 CFR 27.397 - Limit pilot forces and torques.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Limit pilot forces and torques. 27.397... System Loads § 27.397 Limit pilot forces and torques. (a) Except as provided in paragraph (b) of this section, the limit pilot forces are as follows: (1) For foot controls, 130 pounds. (2) For stick...

  8. 14 CFR 23.397 - Limit control forces and -torques.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Limit control forces and -torques. 23.397... Control Surface and System Loads § 23.397 Limit control forces and -torques. (a) In the control surface... exceed those that would result in flight from the application of any pilot force within the...

  9. 14 CFR 23.397 - Limit control forces and -torques.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Limit control forces and -torques. 23.397... Control Surface and System Loads § 23.397 Limit control forces and -torques. (a) In the control surface... exceed those that would result in flight from the application of any pilot force within the...

  10. 14 CFR 29.397 - Limit pilot forces and torques.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Limit pilot forces and torques. 29.397... System Loads § 29.397 Limit pilot forces and torques. (a) Except as provided in paragraph (b) of this section, the limit pilot forces are as follows: (1) For foot controls, 130 pounds. (2) For stick...

  11. Spin-torque generation in topological insulator based heterostructures

    NASA Astrophysics Data System (ADS)

    Fischer, Mark H.; Vaezi, Abolhassan; Manchon, Aurelien; Kim, Eun-Ah

    2016-03-01

    Heterostructures utilizing topological insulators exhibit a remarkable spin-torque efficiency. However, the exact origin of the strong torque, in particular whether it stems from the spin-momentum locking of the topological surface states or rather from spin-Hall physics of the topological-insulator bulk, remains unclear. Here, we explore a mechanism of spin-torque generation purely based on the topological surface states. We consider topological-insulator-based bilayers involving ferromagnetic metal (TI/FM) and magnetically doped topological insulators (TI/mdTI), respectively. By ascribing the key theoretical differences between the two setups to location and number of active surface states, we describe both setups within the same framework of spin diffusion of the nonequilibrium spin density of the topological surface states. For the TI/FM bilayer, we find large spin-torque efficiencies of roughly equal magnitude for both in-plane and out-of-plane spin torques. For the TI/mdTI bilayer, we elucidate the dominance of the spin-transfer-like torque. However, we cannot explain the orders of magnitude enhancement reported. Nevertheless, our model gives an intuitive picture of spin-torque generation in topological-insulator-based bilayers and provides theoretical constraints on spin-torque generation due to topological surface states.

  12. 40 CFR 1066.240 - Torque transducer verification and calibration.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... transducer verification and calibration. Calibrate torque-measurement systems as described in 40 CFR 1065.310. ... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Torque transducer verification and calibration. 1066.240 Section 1066.240 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY...

  13. Torque Sensor Based on Tunnel-Diode Oscillator

    NASA Technical Reports Server (NTRS)

    Chui, Talso; Young, Joseph

    2008-01-01

    A proposed torque sensor would be capable of operating over the temperature range from 1 to 400 K, whereas a typical commercially available torque sensor is limited to the narrower temperature range of 244 to 338 K. The design of this sensor would exploit the wide temperature range and other desirable attributes of differential transducers based on tunnel-diode oscillators as described in "Multiplexing Transducers Based on Tunnel-Diode Oscillators". The proposed torque sensor would include three flexural springs that would couple torque between a hollow outer drive shaft and a solid inner drive shaft. The torque would be deduced from the torsional relative deflection of the two shafts, which would be sensed via changes in capacitances of two capacitors defined by two electrodes attached to the inner shaft and a common middle electrode attached to the outer shaft.

  14. Dynamics of domain wall driven by spin-transfer torque

    SciTech Connect

    Chureemart, P.; Evans, R. F. L.; Chantrell, R. W.

    2011-05-01

    Spin-torque switching of magnetic devices offers new technological possibilities for data storage and integrated circuits. We have investigated domain-wall motion in a ferromagnetic thin film driven by a spin-polarized current using an atomistic spin model with a modified Landau-Lifshitz-Gilbert equation including the effect of the spin-transfer torque. The presence of the spin-transfer torque is shown to create an out-of-plane domain wall, in contrast to the external-field-driven case where an in-plane wall is found. We have investigated the effect of the spin torque on domain-wall displacement, domain-wall velocity, and domain-wall width, as well as the equilibration time in the presence of the spin-transfer torque. We have shown that the minimum spin-current density, regarded as the critical value for domain-wall motion, decreases with increasing temperature.

  15. Approaching the standard quantum limit of mechanical torque sensing

    PubMed Central

    Kim, P. H.; Hauer, B. D.; Doolin, C.; Souris, F.; Davis, J. P.

    2016-01-01

    Reducing the moment of inertia improves the sensitivity of a mechanically based torque sensor, the parallel of reducing the mass of a force sensor, yet the correspondingly small displacements can be difficult to measure. To resolve this, we incorporate cavity optomechanics, which involves co-localizing an optical and mechanical resonance. With the resulting enhanced readout, cavity-optomechanical torque sensors are now limited only by thermal noise. Further progress requires thermalizing such sensors to low temperatures, where sensitivity limitations are instead imposed by quantum noise. Here, by cooling a cavity-optomechanical torque sensor to 25 mK, we demonstrate a torque sensitivity of 2.9 yNm/. At just over a factor of ten above its quantum-limited sensitivity, such cryogenic optomechanical torque sensors will enable both static and dynamic measurements of integrated samples at the level of a few hundred spins. PMID:27762273

  16. Maximum Torque and Momentum Envelopes for Reaction Wheel Arrays

    NASA Technical Reports Server (NTRS)

    Markley, F. Landis; Reynolds, Reid G.; Liu, Frank X.; Lebsock, Kenneth L.

    2009-01-01

    Spacecraft reaction wheel maneuvers are limited by the maximum torque and/or angular momentum that the wheels can provide. For an n-wheel configuration, the torque or momentum envelope can be obtained by projecting the n-dimensional hypercube, representing the domain boundary of individual wheel torques or momenta, into three dimensional space via the 3xn matrix of wheel axes. In this paper, the properties of the projected hypercube are discussed, and algorithms are proposed for determining this maximal torque or momentum envelope for general wheel configurations. Practical strategies for distributing a prescribed torque or momentum among the n wheels are presented, with special emphasis on configurations of four, five, and six wheels.

  17. Special-Purpose High-Torque Permanent-Magnet Motors

    NASA Technical Reports Server (NTRS)

    Doane, George B., III

    1995-01-01

    Permanent-magnet brushless motors that must provide high commanded torques and satisfy unusual heat-removal requirement are developed. Intended for use as thrust-vector-control actuators in large rocket engines. Techniques and concepts used to design improved motors for special terrestrial applications. Conceptual motor design calls for use of rotor containing latest high-energy-product rare-earth permanent magnets so that motor produces required torque while drawing smallest possible currents from power supply. Torque generated by electromagnetic interaction between stator and permanent magnets in rotor when associated electronic circuits applied appropriately temporally and spatially phased currents to stator windings. Phase relationships needed to produce commanded torque computed in response to torque command and to electronically sensed angular position of rotor relative to stator.

  18. Spin Transfer Torque Generated by the Topological Insulator Bismuth Selenide

    NASA Astrophysics Data System (ADS)

    Mellnik, Alex; Grab, Jennifer L.; Mintun, Peter J.; Lee, Joon S.; Richardella, Anthony; Buhrman, Robert A.; Samarth, Nitin; Ralph, Dan C.

    2014-03-01

    We measure large spin-transfer torques generated by in-plane currents in thin films of the topological insulator bismuth selenide at room temperature. We use spin-torque ferromagnetic resonance in Bi2Se3/Ni81Fe19 bilayers to determine that the spin-torque arising from the Bi2Se3 and acting on the Ni81Fe19 layer possesses substantial vector components both in the sample plane and perpendicular to the plane. The out-of-plane torque is several times larger than expected from the Oersted field, and the efficiency of in-plane (anti-damping) spin torque generation per unit current density in the Bi2Se3 is greater than has been observed in any other material.

  19. Time efficient spacecraft maneuver using constrained torque distribution

    NASA Astrophysics Data System (ADS)

    Cao, Xibin; Yue, Chengfei; Liu, Ming; Wu, Baolin

    2016-06-01

    This paper investigates the time efficient maneuver of rigid satellites with inertia uncertainty and bounded external disturbance. A redundant cluster of four reaction wheels is used to control the spacecraft. To make full use of the controllability and avoid frequent unload for reaction wheels, a maximum output torque and maximum angular momentum constrained torque distribution method is developed. Based on this distribution approach, the maximum allowable acceleration and velocity of the satellite are optimized during the maneuvering. A novel braking curve is designed on the basis of the optimization strategy of the control torque distribution. A quaternion-based sliding mode control law is proposed to render the state to track the braking curve strictly. The designed controller provides smooth control torque, time efficiency and high control precision. Finally, practical numerical examples are illustrated to show the effectiveness of the developed torque distribution strategy and control methodology.

  20. Forces and Torques on Rotating Spirochete Flagella

    NASA Astrophysics Data System (ADS)

    Yang, Jing; Huber, Greg; Wolgemuth, Charles W.

    2011-12-01

    Spirochetes are a unique group of motile bacteria that are distinguished by their helical or flat-wave shapes and the location of their flagella, which reside within the tiny space between the bacterial cell wall and the outer membrane (the periplasm). In Borrelia burgdorferi, rotation of the flagella produces cellular undulations that drive swimming. How these shape changes arise due to the forces and torques that act between the flagella and the cell body is unknown. It is possible that resistive forces come from friction or from fluid drag, depending on whether or not the flagella are in contact with the cell wall. Here, we consider both of these cases. By analyzing the motion of an elastic flagellum rotating in the periplasmic space, we show that the flagella are most likely separated from the bacterial cell wall by a lubricating layer of fluid. This analysis then provides drag coefficients for rotation and sliding of a flagellum within the periplasm.

  1. Forces and Torques on Rotating Spirochete Flagella

    PubMed Central

    Yang, Jing; Huber, Greg; Wolgemuth, Charles W.

    2012-01-01

    Spirochetes are a unique group of motile bacteria that are distinguished by their helical or flat-wave shapes and the location of their flagella, which reside within the tiny space between the bacterial cell wall and the outer membrane (the periplasm). In Borrelia burgdorferi, rotation of the flagella produces cellular undulations that drive swimming. How these shape changes arise due to the forces and torques that act between the flagella and the cell body is unknown. It is possible that resistive forces come from friction or from fluid drag, depending on whether or not the flagella are in contact with the cell wall. Here, we consider both of these cases. By analyzing the motion of an elastic flagellum rotating in the periplasmic space, we show that the flagella are most likely separated from the bacterial cell wall by a lubricating layer of fluid. This analysis then provides drag coefficients for rotation and sliding of a flagellum within the periplasm. PMID:22243185

  2. Torque Splitting by a Concentric Face Gear Transmission

    NASA Technical Reports Server (NTRS)

    Filler, Robert R.; Heath, Gregory F.; Slaughter, Stephen C.; Lewicki, David G.

    2002-01-01

    Tests of a 167 Kilowatt (224 Horsepower) split torque face gearbox were performed by the Boeing Company in Mesa, Arizona, while working under a Defense Advanced Research Projects Agency (DARPA) Technology Reinvestment Program (TRP). This paper provides a summary of these cooperative tests, which were jointly funded by Boeing and DARPA. Design, manufacture and testing of the scaled-power TRP proof-of-concept (POC) split torque gearbox followed preliminary evaluations of the concept performed early in the program. The split torque tests were run using 200 N-m (1767 in-lbs) torque input to each side of the transmission. During tests, two input pinions were slow rolled while in mesh with the two face gears. Two idler gears were also used in the configuration to recombine torque near the output. Resistance was applied at the output face gear to create the required loading conditions in the gear teeth. A system of weights, pulleys and cables were used in the test rig to provide both the input and output loading. Strain gages applied in the tooth root fillets provided strain indication used to determine torque splitting conditions at the input pinions. The final two pinion-two idler tests indicated 52% to 48% average torque split capabilities for the two pinions. During the same tests, a 57% to 43% average distribution of the torque being recombined to the upper face gear from the lower face gear was measured between the two idlers. The POC split torque tests demonstrated that face gears can be applied effectively in split torque rotorcraft transmissions, yielding good potential for significant weight, cost and reliability improvements over existing equipment using spiral bevel gearing.

  3. Gravity gradient torque profiles over an orbit for arbitrary modular space station configurations in the Y-POP and inertial hold modes

    NASA Technical Reports Server (NTRS)

    Mcgill, D. J.

    1972-01-01

    For several proposed configurations of the modular space station, the gravity gradient torque distribution is examined for both Y-POP and inertial hold orbits. The necessary equations are derived to allow for solar panel gimbaling, and a procedure is established which will allow any desired space station configuration to be built up. Results indicated that solar panel gimbaling can be a significant factor in the torque distribution in Y-POP orbits. In addition, for the two configurations that were plotted, bias torque magnitudes varied widely in inertial hold modes.

  4. Unsteady aerodynamic forces and torques on falling parallelograms in coupled tumbling-helical motions.

    PubMed

    Varshney, Kapil; Chang, Song; Wang, Z Jane

    2013-05-01

    Falling parallelograms exhibit coupled motion of autogyration and tumbling, similar to the motion of falling tulip seeds, unlike maple seeds which autogyrate but do not tumble, or rectangular cards which tumble but do not gyrate. This coupled tumbling and autogyrating motion are robust, when card parameters, such as aspect ratio, internal angle, and mass density, are varied. We measure the three-dimensional (3D) falling kinematics of the parallelograms and quantify their descending speed, azimuthal rotation, tumbling rotation, and cone angle in each falling. The cone angle is insensitive to the variation of the card parameters, and the card tumbling axis does not overlap with but is close to the diagonal axis. In addition to this connection to the dynamics of falling seeds, these trajectories provide an ideal set of data to analyze 3D aerodynamic force and torque at an intermediate range of Reynolds numbers, and the results will be useful for constructing 3D aerodynamic force and torque models. Tracking these free falling trajectories gives us a nonintrusive method for deducing instantaneous aerodynamic forces. We determine the 3D aerodynamic forces and torques based on Newton-Euler equations. The dynamical analysis reveals that, although the angle of attack changes dramatically during tumbling, the aerodynamic forces have a weak dependence on the angle of attack. The aerodynamic lift is dominated by the coupling of translational and rotational velocities. The aerodynamic torque has an unexpectedly large component perpendicular to the card. The analysis of the Euler equation suggests that this large torque is related to the deviation of the tumbling axis from the principle axis of the card. PMID:23767634

  5. Unsteady aerodynamic forces and torques on falling parallelograms in coupled tumbling-helical motions.

    PubMed

    Varshney, Kapil; Chang, Song; Wang, Z Jane

    2013-05-01

    Falling parallelograms exhibit coupled motion of autogyration and tumbling, similar to the motion of falling tulip seeds, unlike maple seeds which autogyrate but do not tumble, or rectangular cards which tumble but do not gyrate. This coupled tumbling and autogyrating motion are robust, when card parameters, such as aspect ratio, internal angle, and mass density, are varied. We measure the three-dimensional (3D) falling kinematics of the parallelograms and quantify their descending speed, azimuthal rotation, tumbling rotation, and cone angle in each falling. The cone angle is insensitive to the variation of the card parameters, and the card tumbling axis does not overlap with but is close to the diagonal axis. In addition to this connection to the dynamics of falling seeds, these trajectories provide an ideal set of data to analyze 3D aerodynamic force and torque at an intermediate range of Reynolds numbers, and the results will be useful for constructing 3D aerodynamic force and torque models. Tracking these free falling trajectories gives us a nonintrusive method for deducing instantaneous aerodynamic forces. We determine the 3D aerodynamic forces and torques based on Newton-Euler equations. The dynamical analysis reveals that, although the angle of attack changes dramatically during tumbling, the aerodynamic forces have a weak dependence on the angle of attack. The aerodynamic lift is dominated by the coupling of translational and rotational velocities. The aerodynamic torque has an unexpectedly large component perpendicular to the card. The analysis of the Euler equation suggests that this large torque is related to the deviation of the tumbling axis from the principle axis of the card.

  6. Reliability of metatarsophalangeal and ankle joint torque measurements by an innovative device.

    PubMed

    Man, Hok-Sum; Leung, Aaron Kam-Lun; Cheung, Jason Tak-Man; Sterzing, Thorsten

    2016-07-01

    The toe flexor muscles maintain body balance during standing and provide push-off force during walking, running, and jumping. Additionally, they are important contributing structures to maintain normal foot function. Thus, weakness of these muscles may cause poor balance, inefficient locomotion and foot deformities. The quantification of metatarsophalangeal joint (MPJ) stiffness is valuable as it is considered as a confounding factor in toe flexor muscles function. MPJ and ankle joint stiffness measurement is still largely depended on manual skills as current devices do not have good control on alignment, angular joint speed and displacement during measurement. Therefore, this study introduces an innovative dynamometer and protocol procedures for MPJ and ankle Joint torque measurement with precise and reliable foot alignment, angular joint speed and displacement control. Within-day and between-day test-retest experiments on MPJ and ankle joint torque measurement were conducted on ten and nine healthy male subjects respectively. The mean peak torques of MPJ and ankle joint of between-day and within-day measurement were 1.50±0.38Nm/deg and 1.19±0.34Nm/deg. The corresponding torques of the ankle joint were 8.24±2.20Nm/deg and 7.90±3.18Nm/deg respectively. Intraclass-correlation coefficients (ICC) of averaged peak torque of both joints of between-day and within-day test-retest experiments were ranging from 0.91 to 0.96, indicating the innovative device is systematic and reliable for the measurements and can be used for multiple scientific and clinical purposes.

  7. Unsteady aerodynamic forces and torques on falling parallelograms in coupled tumbling-helical motions

    NASA Astrophysics Data System (ADS)

    Varshney, Kapil; Chang, Song; Wang, Z. Jane

    2013-05-01

    Falling parallelograms exhibit coupled motion of autogyration and tumbling, similar to the motion of falling tulip seeds, unlike maple seeds which autogyrate but do not tumble, or rectangular cards which tumble but do not gyrate. This coupled tumbling and autogyrating motion are robust, when card parameters, such as aspect ratio, internal angle, and mass density, are varied. We measure the three-dimensional (3D) falling kinematics of the parallelograms and quantify their descending speed, azimuthal rotation, tumbling rotation, and cone angle in each falling. The cone angle is insensitive to the variation of the card parameters, and the card tumbling axis does not overlap with but is close to the diagonal axis. In addition to this connection to the dynamics of falling seeds, these trajectories provide an ideal set of data to analyze 3D aerodynamic force and torque at an intermediate range of Reynolds numbers, and the results will be useful for constructing 3D aerodynamic force and torque models. Tracking these free falling trajectories gives us a nonintrusive method for deducing instantaneous aerodynamic forces. We determine the 3D aerodynamic forces and torques based on Newton-Euler equations. The dynamical analysis reveals that, although the angle of attack changes dramatically during tumbling, the aerodynamic forces have a weak dependence on the angle of attack. The aerodynamic lift is dominated by the coupling of translational and rotational velocities. The aerodynamic torque has an unexpectedly large component perpendicular to the card. The analysis of the Euler equation suggests that this large torque is related to the deviation of the tumbling axis from the principle axis of the card.

  8. Estimations of One Repetition Maximum and Isometric Peak Torque in Knee Extension Based on the Relationship Between Force and Velocity.

    PubMed

    Sugiura, Yoshito; Hatanaka, Yasuhiko; Arai, Tomoaki; Sakurai, Hiroaki; Kanada, Yoshikiyo

    2016-04-01

    We aimed to investigate whether a linear regression formula based on the relationship between joint torque and angular velocity measured using a high-speed video camera and image measurement software is effective for estimating 1 repetition maximum (1RM) and isometric peak torque in knee extension. Subjects comprised 20 healthy men (mean ± SD; age, 27.4 ± 4.9 years; height, 170.3 ± 4.4 cm; and body weight, 66.1 ± 10.9 kg). The exercise load ranged from 40% to 150% 1RM. Peak angular velocity (PAV) and peak torque were used to estimate 1RM and isometric peak torque. To elucidate the relationship between force and velocity in knee extension, the relationship between the relative proportion of 1RM (% 1RM) and PAV was examined using simple regression analysis. The concordance rate between the estimated value and actual measurement of 1RM and isometric peak torque was examined using intraclass correlation coefficients (ICCs). Reliability of the regression line of PAV and % 1RM was 0.95. The concordance rate between the actual measurement and estimated value of 1RM resulted in an ICC(2,1) of 0.93 and that of isometric peak torque had an ICC(2,1) of 0.87 and 0.86 for 6 and 3 levels of load, respectively. Our method for estimating 1RM was effective for decreasing the measurement time and reducing patients' burden. Additionally, isometric peak torque can be estimated using 3 levels of load, as we obtained the same results as those reported previously. We plan to expand the range of subjects and examine the generalizability of our results.

  9. Estimations of One Repetition Maximum and Isometric Peak Torque in Knee Extension Based on the Relationship Between Force and Velocity.

    PubMed

    Sugiura, Yoshito; Hatanaka, Yasuhiko; Arai, Tomoaki; Sakurai, Hiroaki; Kanada, Yoshikiyo

    2016-04-01

    We aimed to investigate whether a linear regression formula based on the relationship between joint torque and angular velocity measured using a high-speed video camera and image measurement software is effective for estimating 1 repetition maximum (1RM) and isometric peak torque in knee extension. Subjects comprised 20 healthy men (mean ± SD; age, 27.4 ± 4.9 years; height, 170.3 ± 4.4 cm; and body weight, 66.1 ± 10.9 kg). The exercise load ranged from 40% to 150% 1RM. Peak angular velocity (PAV) and peak torque were used to estimate 1RM and isometric peak torque. To elucidate the relationship between force and velocity in knee extension, the relationship between the relative proportion of 1RM (% 1RM) and PAV was examined using simple regression analysis. The concordance rate between the estimated value and actual measurement of 1RM and isometric peak torque was examined using intraclass correlation coefficients (ICCs). Reliability of the regression line of PAV and % 1RM was 0.95. The concordance rate between the actual measurement and estimated value of 1RM resulted in an ICC(2,1) of 0.93 and that of isometric peak torque had an ICC(2,1) of 0.87 and 0.86 for 6 and 3 levels of load, respectively. Our method for estimating 1RM was effective for decreasing the measurement time and reducing patients' burden. Additionally, isometric peak torque can be estimated using 3 levels of load, as we obtained the same results as those reported previously. We plan to expand the range of subjects and examine the generalizability of our results. PMID:26382131

  10. Motor readiness and joint torque production in lower limbs of older women fallers and non-fallers.

    PubMed

    Crozara, Luciano Fernandes; Morcelli, Mary Hellen; Marques, Nise Ribeiro; Hallal, Camilla Zamfolini; Spinoso, Deborah Hebling; de Almeida Neto, Antônio Francisco; Cardozo, Adalgiso Coscrato; Gonçalves, Mauro

    2013-10-01

    This study aimed to evaluate the motor response time and ability to develop joint torque at the knee and ankle in older women with and without a history of falls, in addition to investigating the effect of aging on these capacities. We assessed 18 young females, 21 older female fallers and 22 older female non-fallers. The peak torque, rate of torque development, rate of electromyography (EMG) rise, reaction time, premotor time and motor time were obtained through a dynamometric assessment and simultaneous electromyography. Surface EMGs of the rectus femoris (RF), vastus lateralis (VL), biceps femoris (BF), gastrocnemius lateralis (GL) and tibialis anterior (TA) muscles were recorded. Knee extension and flexion peak torques were lower in older fallers than in non-fallers. Knee extension and flexion and ankle plantarflexion and dorsiflexion peak torques were lower in both older groups than in the younger group. The rate of EMG rise of the BF and the motor time of the TA were lower and higher, respectively, in older fallers than in the younger adults. The time to reach peak torque in knee extension/flexion and ankle plantarflexion/dorsiflexion and the motor times of the RF, VL, BF and GL were higher in both older groups than in the younger groups. The motor time of the TA during ankle dorsiflexion and the knee extension peak torque were the major predictors of falls in older women, accounting for approximately 28% of the number of falls. Thus, these results further reveal the biomechanical parameters that affect the risk of falls and provide initial findings to support the prescription of exercises in fall prevention programs.

  11. Transiting exoplanets from the CoRoT space mission⋆. XXVIII. CoRoT-33b, an object in the brown dwarf desert with 2:3 commensurability with its host star

    NASA Astrophysics Data System (ADS)

    Csizmadia, Sz.; Hatzes, A.; Gandolfi, D.; Deleuil, M.; Bouchy, F.; Fridlund, M.; Szabados, L.; Parviainen, H.; Cabrera, J.; Aigrain, S.; Alonso, R.; Almenara, J.-M.; Baglin, A.; Bordé, P.; Bonomo, A. S.; Deeg, H. J.; Díaz, R. F.; Erikson, A.; Ferraz-Mello, S.; Tadeu dos Santos, M.; Guenther, E. W.; Guillot, T.; Grziwa, S.; Hébrard, G.; Klagyivik, P.; Ollivier, M.; Pätzold, M.; Rauer, H.; Rouan, D.; Santerne, A.; Schneider, J.; Mazeh, T.; Wuchterl, G.; Carpano, S.; Ofir, A.

    2015-12-01

    We report the detection of a rare transiting brown dwarf with a mass of 59 MJup and radius of 1.1 RJup around the metal-rich, [Fe/H] = +0.44, G9V star CoRoT-33. The orbit is eccentric (e = 0.07) with a period of 5.82 d. The companion, CoRoT-33b, is thus a new member in the so-called brown dwarf desert. The orbital period is within 3% to a 3:2 resonance with the rotational period of the star. CoRoT-33b may be an important test case for tidal evolution studies. The true frequency of brown dwarfs close to their host stars (P< 10 d) is estimated to be approximately 0.2% which is about six times smaller than the frequency of hot Jupiters in the same period range. We suspect that the frequency of brown dwarfs declines faster with decreasing period than that of giant planets. The CoRoT space mission, launched on December 27th 2006, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany and Spain. Based on observations made with HARPS (High Accuracy Radial velocity Planet Searcher) spectrograph on the 3.6-m European Organisation for Astronomical Research in the Southern Hemisphere telescope at La Silla Observatory, Chile (ESO program 188.C-0779).Based on observations obtained with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias, in time allocated by the Spanish Time Allocation Committee (CAT).

  12. Lunar and Solar Torques on the Oceanic Tides

    NASA Technical Reports Server (NTRS)

    Ray, Richard D.; Bills, Bruce G.; Chao, Benjamin F.

    1998-01-01

    Brosche and Seiler recently suggested that direct lunar and solar tidal torques on the oceanic tides play a significant role in the earth's short-period angular momentum balance ("short-period" here meaning daily and sub-daily). We reexamine that suggestion here, concentrating on axial torques and hence on variations in rotation rate. Only those spherical harmonic components of the ocean tide having the same degree and order as the tidal potential induce nonzero torques. Prograde components (those moving in the same direction as the tide-generating body) produce the familiar secular braking of the earth's rotation. Retrograde components, however, produce rapid variations in UTI at twice the tidal frequency. There also exist interaction torques between tidal constituents, e.g. solar torques on lunar tides. They generate UTI variations at frequencies equal to the sums and differences of the original tidal frequencies. We give estimates of the torques and angular momentum variations for each of the important regimes, secular to quarter-diurnal. For the M(sub 2) potential acting on the M(sub 2) ocean tide, we find an associated angular momentum variation of amplitude 3 x 10(exp 19) N m. This is 5 to 6 orders of magnitude smaller than the angular momentum variations associated with tidal currents. We conclude that these torques do not play a significant role in the short-period angular momentum balance.

  13. Spin torque and Nernst effects in Dzyaloshinskii-Moriya ferromagnets

    DOE PAGES

    Kovalev, Alexey A.; Zyuzin, Vladimir

    2016-04-11

    Here, we predict that a temperature gradient can induce a magnon-mediated intrinsic torque in systems with a nontrivial magnon Berry curvature. With the help of a microscopic linear response theory of nonequilibrium magnon-mediated torques and spin currents we identify the interband and intraband components that manifest in ferromagnets with Dzyaloshinskii-Moriya interactions and magnetic textures. To illustrate and assess the importance of such effects, we apply the linear response theory to the magnon-mediated spin Nernst and torque responses in a kagome lattice ferromagnet.

  14. Antiferromagnetic Domain Wall Motion Driven by Spin-Orbit Torques.

    PubMed

    Shiino, Takayuki; Oh, Se-Hyeok; Haney, Paul M; Lee, Seo-Won; Go, Gyungchoon; Park, Byong-Guk; Lee, Kyung-Jin

    2016-08-19

    We theoretically investigate the dynamics of antiferromagnetic domain walls driven by spin-orbit torques in antiferromagnet-heavy-metal bilayers. We show that spin-orbit torques drive antiferromagnetic domain walls much faster than ferromagnetic domain walls. As the domain wall velocity approaches the maximum spin-wave group velocity, the domain wall undergoes Lorentz contraction and emits spin waves in the terahertz frequency range. The interplay between spin-orbit torques and the relativistic dynamics of antiferromagnetic domain walls leads to the efficient manipulation of antiferromagnetic spin textures and paves the way for the generation of high frequency signals from antiferromagnets. PMID:27588878

  15. A flight simulator control system using electric torque motors

    NASA Technical Reports Server (NTRS)

    Musick, R. O.; Wagner, C. A.

    1975-01-01

    Control systems are required in flight simulators to provide representative stick and rudder pedal characteristics. A system has been developed that uses electric dc torque motors instead of the more common hydraulic actuators. The torque motor system overcomes certain disadvantages of hydraulic systems, such as high cost, high power consumption, noise, oil leaks, and safety problems. A description of the torque motor system is presented, including both electrical and mechanical design as well as performance characteristics. The system develops forces sufficiently high for most simulations, and is physically small and light enough to be used in most motion-base cockpits.

  16. Surface modification of clutch plates to reduce disengaged drag torque

    NASA Astrophysics Data System (ADS)

    Aphale, Chinar R.

    2005-11-01

    Viscous drag torque in disengaged clutches is a significant source of power loss in modern transportation. The main way to reduce this drag torque is to introduce air between the plates when disengaged without reducing the transmission fluid flow eventually needed for reengagement. Six different groove patterns are tested experimentally to determine which have the lowest drag characteristics. Our computations using Fluent showed that the contact angle made by oil with the stationary plate is critical in determining aeration initiation. Experiments coating the stationary plate with an oleophobic substance like Teflon, confirmed these simulations. We will show torque comparisons and visualization through a quartz disk acting as one of the clutch plates.

  17. Antiferromagnetic Domain Wall Motion Driven by Spin-Orbit Torques

    NASA Astrophysics Data System (ADS)

    Shiino, Takayuki; Oh, Se-Hyeok; Haney, Paul M.; Lee, Seo-Won; Go, Gyungchoon; Park, Byong-Guk; Lee, Kyung-Jin

    2016-08-01

    We theoretically investigate the dynamics of antiferromagnetic domain walls driven by spin-orbit torques in antiferromagnet-heavy-metal bilayers. We show that spin-orbit torques drive antiferromagnetic domain walls much faster than ferromagnetic domain walls. As the domain wall velocity approaches the maximum spin-wave group velocity, the domain wall undergoes Lorentz contraction and emits spin waves in the terahertz frequency range. The interplay between spin-orbit torques and the relativistic dynamics of antiferromagnetic domain walls leads to the efficient manipulation of antiferromagnetic spin textures and paves the way for the generation of high frequency signals from antiferromagnets.

  18. Radiative torque alignment: essential physical processes

    NASA Astrophysics Data System (ADS)

    Hoang, Thiem; Lazarian, A.

    2008-07-01

    We study the physical processes that affect the alignment of grains subject to radiative torques (RATs). To describe the action of RATs, we use the analytical model (AMO) of RATs introduced in our previous paper. We focus our discussion on the alignment by anisotropic radiation flux with respect to the magnetic field, which defines the axis of grain Larmor precession. Such an alignment does not invoke paramagnetic dissipation (i.e. the Davis-Greenstein mechanism), but, nevertheless, grains tend to be aligned with long axes perpendicular to the magnetic field. When we account for thermal fluctuations within grains, we show that for grains that are characterized by a triaxial ellipsoid of inertia, the zero-J attractor point obtained in our earlier study develops into a low-J attractor point. The value of angular momentum at the low-J attractor point is of the order of the thermal angular momentum corresponding to the grain temperature. We show that, for situations when the direction of radiative flux is nearly perpendicular to a magnetic field, the alignment of grains with long axes parallel to the magnetic field (i.e. `wrong alignment') reported in our previous paper, disappears in the presence of thermal fluctuations. Thus, all grains are aligned with their long axes perpendicular to the magnetic field. We study the effects of stochastic gaseous bombardment and show that gaseous bombardment can drive grains from low-J to high-J attractor points in cases when high-J attractor points are present. As the alignment of grain axes with respect to angular momentum is higher for higher values of J, counter-intuitively, gaseous bombardment can increase the degree of grain alignment with respect to the magnetic field. We also study the effects of torques induced by H2 formation and show that they can change the value of angular momentum at high-J attractor points, but marginally affect the value of angular momentum at low-J attractor points. We compare the AMO results with

  19. VizieR Online Data Catalog: GTC transit light curves of CoRoT-29b (Palle+, 2016)

    NASA Astrophysics Data System (ADS)

    Palle, E.; Chen, G.; Alonso, R.; Nowak, G.; Deeg, H.; Cabrera, J.; Murgas, F.; Parviainen, H.; Nortmann, L.; Hoyer, S.; Prieto-Arranz, J.; Nespral, D.; Cabrera Lavers, A.; Iro, N.

    2016-04-01

    2 transit light curves of the hot Jupiter CoRoT-29b obtained on the nights of 2014/7/31 and 2015/7/8 using the OSIRIS instrument at the 10.4-m GTC telescope. The light curves have been integrated over the bandpass of 515-915nm, where the wavelength range of 755-765 nm has been excluded due to presence of strong telluric O2 absorption. (2 data files).

  20. Solar-like oscillations in HD 181420: data analysis of 156 days of CoRoT data

    NASA Astrophysics Data System (ADS)

    Barban, C.; Deheuvels, S.; Baudin, F.; Appourchaux, T.; Auvergne, M.; Ballot, J.; Boumier, P.; Chaplin, W. J.; García, R. A.; Gaulme, P.; Michel, E.; Mosser, B.; Régulo, C.; Roxburgh, I. W.; Verner, G.; Baglin, A.; Catala, C.; Samadi, R.; Bruntt, H.; Elsworth, Y.; Mathur, S.

    2009-10-01

    Context: The estimate of solar-like oscillation properties, such as their frequencies, amplitudes and lifetimes, is challenging because of their low amplitudes and will benefit from long and uninterrupted observing runs. The space telescope CoRoT allows us to obtain high-performance photometric data over a long and quasi continuous period. Among its main targets are stars for which we expect solar-like oscillations. Aims: HD 181420, an F2 main sequence star, has been observed by CoRoT during its first long run covering about 156 days. With this unprecedently high-quality set of data, our aim is to derive the p-mode parameters that can be used to probe the stellar interior. Methods: The CoRoT data obtained on HD 181420 is analysed using a classical Fourier approach for the search for the p mode signature. The p-mode parameters are then derived using global fitting of the power spectrum by a Lorentzian model, as used widely in the solar case. Results: From the p-mode frequencies, the mean value of the large spacing is estimated to be 75 {μ Hz}. The p-mode amplitudes are slightly less than 4 ppm with a line width of about 8 {μ Hz} at the maximum of the p modes. The inclination angle is estimated to be around 45 °. The large mode line-width combined with the observed mode spacing make it difficult to identify the ℓ=2 modes and to estimate the rotational splitting. We explore two scenarios for the identification of the modes. The CoRoT space mission, launched on 2006 December 27, was delopped and is operated by the CNES with participation of the Science Programs of ESA; ESA's RSSD, Austria, Belgium, Brazil, Germany and Spain.

  1. A fresh look at the seismic spectrum of HD49933: analysis of 180 days of CoRoT photometry

    NASA Astrophysics Data System (ADS)

    Benomar, O.; Baudin, F.; Campante, T. L.; Chaplin, W. J.; García, R. A.; Gaulme, P.; Toutain, T.; Verner, G. A.; Appourchaux, T.; Ballot, J.; Barban, C.; Elsworth, Y.; Mathur, S.; Mosser, B.; Régulo, C.; Roxburgh, I. W.; Auvergne, M.; Baglin, A.; Catala, C.; Michel, E.; Samadi, R.

    2009-11-01

    Context: Solar-like oscillations have now been observed in several stars, thanks to ground-based spectroscopic observations and space-borne photometry. CoRoT, which has been in orbit since December 2006, has observed the star HD49933 twice. The oscillation spectrum of this star has proven difficult to interpret. Aims: Thanks to a new timeseries provided by CoRoT, we aim to provide a robust description of the oscillations in HD49933, i.e., to identify the degrees of the observed modes, and to measure mode frequencies, widths, amplitudes and the average rotational splitting. Methods: Several methods were used to model the Fourier spectrum: Maximum Likelihood Estimators and Bayesian analysis using Markov Chain Monte-Carlo techniques. Results: The different methods yield consistent result, and allow us to make a robust identification of the modes and to extract precise mode parameters. Only the rotational splitting remains difficult to estimate precisely, but is clearly relatively large (several μHz in size). The CoRoT space mission, launched on 2006 December 27, was developed and is operated by the CNES, with participation of the Science Programs of ESA, ESA's RSSD, Austria, Belgium, Brazil, Germany and Spain. Figures 5-9 and Table 2 are only available in electronic form at http://www.aanda.org

  2. Preparing the COROT space mission: Building a photometric and variability database of stars in its field of view

    NASA Astrophysics Data System (ADS)

    Amado, P. J.; Garrido, R.; Poretti, E.; Michel, E.

    2004-05-01

    The CNES/European space mission COROT will monitor astereoseismic targets located in selected fields to probe stellar interiors. Therefore, suitable candidate targets have to be searched for in order to optimize the scientific return of the mission. However, to be able to use the asteroseismic tools on the stars, their physical parameters must be known in advance. In this work, we detail the process of building a photometric database of all the stars brighter than V = 8.0 in the field of view of COROT and the process of selecting suitable δ Sct and γ Dor-type stars for the mission For an optimal selection of the seismology targets (for both COROT programs devoted to asteroseismology, i.e., the core and exploratory ones), it is essential to gather a priori as much information as possible on all potential candidates. With this aim, Strömgren-Crawford uvby-Hβ and Ca II H&K photometry were obtained for all of them. These data have been used to derive estimates of their effective temperatures, surface gravities and metallicities. These observations, together with high resolution imaging observations, are components of an ambitious ground-based program.

  3. Absolute reliability of hamstring to quadriceps strength imbalance ratios calculated using peak torque, joint angle-specific torque and joint ROM-specific torque values.

    PubMed

    Ayala, F; De Ste Croix, M; Sainz de Baranda, P; Santonja, F

    2012-11-01

    The main purpose of this study was to determine the absolute reliability of conventional (H/Q(CONV)) and functional (H/Q(FUNC)) hamstring to quadriceps strength imbalance ratios calculated using peak torque values, 3 different joint angle-specific torque values (10°, 20° and 30° of knee flexion) and 4 different joint ROM-specific average torque values (0-10°, 11-20°, 21-30° and 0-30° of knee flexion) adopting a prone position in recreational athletes. A total of 50 recreational athletes completed the study. H/Q(CONV) and H/Q(FUNC) ratios were recorded at 3 different angular velocities (60, 180 and 240°/s) on 3 different occasions with a 72-96 h rest interval between consecutive testing sessions. Absolute reliability was examined through typical percentage error (CVTE), percentage change in the mean (CM) and intraclass correlations (ICC) as well as their respective confidence limits. H/Q(CONV) and H/Q(FUNC) ratios calculated using peak torque values showed moderate reliability values, with CM scores lower than 2.5%, CV(TE) values ranging from 16 to 20% and ICC values ranging from 0.3 to 0.7. However, poor absolute reliability scores were shown for H/Q(CONV) and H/Q(FUNC) ratios calculated using joint angle-specific torque values and joint ROM-specific average torque values, especially for H/Q(FUNC) ratios (CM: 1-23%; CV(TE): 22-94%; ICC: 0.1-0.7). Therefore, the present study suggests that the CV(TE) values reported for H/Q(CONV) and H/Q(FUNC) (≈18%) calculated using peak torque values may be sensitive enough to detect large changes usually observed after rehabilitation programmes but not acceptable to examine the effect of preventitive training programmes in healthy individuals. The clinical reliability of hamstring to quadriceps strength ratios calculated using joint angle-specific torque values and joint ROM-specific average torque values are questioned and should be re-evaluated in future research studies.

  4. PREFACE: The Science of Making Torque from Wind 2014 (TORQUE 2014)

    NASA Astrophysics Data System (ADS)

    Mann, Jakob; Bak, Christian; Bechmann, Andreas; Bingöl, Ferhat; Dellwik, Ebba; Dimitrov, Nikolay; Giebel, Gregor; Hansen, Martin O. L.; Jensen, Dorte Juul; Larsen, Gunner; Aagaard Madsen, Helge; Natarajan, Anand; Rathmann, Ole; Sathe, Ameya; Nørkær Sørensen, Jens; Nørkær Sørensen, Niels

    2014-06-01

    The 186 papers in this volume constitute the proceedings of the fifth Science of Making Torque from Wind conference, which is organized by the European Academy of Wind Energy (EAWE, www.eawe.eu). The conference, also called Torque 2014, is held at the Technical University of Denmark (DTU) 17-20 June 2014. The EAWE conference series started in 2004 in Delft, the Netherlands. In 2007 it was held in Copenhagen, in 2010 in Heraklion, Greece, and then in 2012 in Oldenburg, Germany. The global yearly production of electrical energy by wind turbines has grown approximately by 25% annually over the last couple of decades and covers now 2-3% of the global electrical power consumption. In order to make a significant impact on one of the large challenges of our time, namely global warming, the growth has to continue for a decade or two yet. This in turn requires research and education in wind turbine aerodynamics and wind resources, the two topics which are the main subjects of this conference. Similar to the growth in electrical power production by wind is the growth in scientific papers about wind energy. Over the last decade the number of papers has also grown by about 25% annually, and many research based companies all over the world are founded. Hence, the wind energy research community is rapidly expanding and the Torque conference series offers a good opportunity to meet and exchange ideas. We hope that the Torque 2014 will heighten the quality of the wind energy research, while the participants will enjoy each others company in Copenhagen. Many people have been involved in producing the Torque 2014 proceedings. The work by more than two hundred reviewers ensuring the quality of the papers is greatly appreciated. The timely evaluation and coordination of the reviews would not have been possible without the work of sixteen ''section editors'' all from DTU Wind Energy: Christian Bak, Andreas Bechmann, Ferhat Bingöl, Ebba Dellwik, Nikolay Dimitrov, Gregor Giebel, Martin

  5. Deformation of a micro-torque swimmer

    PubMed Central

    Ishikawa, Takuji; Tanaka, Tomoyuki; Imai, Yohsuke; Omori, Toshihiro; Matsunaga, Daiki

    2016-01-01

    The membrane tension of some kinds of ciliates has been suggested to regulate upward and downward swimming velocities under gravity. Despite its biological importance, deformation and membrane tension of a ciliate have not been clarified fully. In this study, we numerically investigated the deformation of a ciliate swimming freely in a fluid otherwise at rest. The cell body was modelled as a capsule with a hyperelastic membrane enclosing a Newtonian fluid. Thrust forces due to the ciliary beat were modelled as torques distributed above the cell body. The effects of membrane elasticity, the aspect ratio of the cell's reference shape, and the density difference between the cell and the surrounding fluid were investigated. The results showed that the cell deformed like a heart shape, when the capillary number was sufficiently large. Under the influence of gravity, the membrane tension at the anterior end decreased in the upward swimming while it increased in the downward swimming. Moreover, gravity-induced deformation caused the cells to move gravitationally downwards or upwards, which resulted in a positive or negative geotaxis-like behaviour with a physical origin. These results are important in understanding the physiology of a ciliate's biological responses to mechanical stimuli. PMID:26997893

  6. Creating Skyrmions Using Spin Transfer Torque

    NASA Astrophysics Data System (ADS)

    Grab, Jennifer; Rugar, Alison; MacNeill, David; Finocchio, Giovanni; Buhrman, Robert; Ralph, Daniel

    Finding efficient methods to read and write individual skyrmions under ambient conditions is an important first step toward realizing skyrmion-based applications, such as high density information storage and racetrack memory. Of recent interest experimentally are heavy metal /ferromagnet bilayers with a strong interfacial Dzyaloshinskii-Moriya Interaction and perpendicular magnetic anisotropy (PMA), which favor the formation of helical spin textures. Micromagnetic simulations of these materials suggest that an out of plane spin polarized current could be used to write isolated skyrmions and excite skyrmion breathing modes. In this project, we attempt to create skyrmions using a spin valve like device. Our devices consist of a PMA nanopillar on top of a bulk Co/Pt bilayer. The nanopillar generates a spin polarized current, which is expected to locally reverse the magnetization of the film underneath the pillar via spin transfer torque. We report measurements of the DC current and field dependence of the pillar resistance. By monitoring the magnetization state of the bilayer independently, these measurements can be used to isolate the resistive signatures of skyrmion formation.

  7. Spin orbit torque based electronic neuron

    SciTech Connect

    Sengupta, Abhronil Choday, Sri Harsha; Kim, Yusung; Roy, Kaushik

    2015-04-06

    A device based on current-induced spin-orbit torque (SOT) that functions as an electronic neuron is proposed in this work. The SOT device implements an artificial neuron's thresholding (transfer) function. In the first step of a two-step switching scheme, a charge current places the magnetization of a nano-magnet along the hard-axis, i.e., an unstable point for the magnet. In the second step, the SOT device (neuron) receives a current (from the synapses) which moves the magnetization from the unstable point to one of the two stable states. The polarity of the synaptic current encodes the excitatory and inhibitory nature of the neuron input and determines the final orientation of the magnetization. A resistive crossbar array, functioning as synapses, generates a bipolar current that is a weighted sum of the inputs. The simulation of a two layer feed-forward artificial neural network based on the SOT electronic neuron shows that it consumes ∼3× lower power than a 45 nm digital CMOS implementation, while reaching ∼80% accuracy in the classification of 100 images of handwritten digits from the MNIST dataset.

  8. Observation of thermal spin-transfer torque via ferromagnetic resonance in magnetic tunnel junctions

    NASA Astrophysics Data System (ADS)

    Zhang, Zhaohui; Bai, Lihui; Chen, Xiaobin; Guo, Hong; Fan, X. L.; Xue, D. S.; Houssameddine, D.; Hu, C.-M.

    2016-08-01

    The thermal spin-transfer torque (TSTT) in magnetic tunneling junctions (MTJs) was systematically studied using electrical detection of ferromagnetic resonance (FMR). Evidence for the existence of TSTT in MTJs is observed. A temperature difference was applied across an MTJ acting as a TSTT on the free layer of the MTJ. The FMR of the free layer was then excited by a microwave current and electrically detected as a dc voltage. We found that the FMR line shape was changed by the TSTT, indicated by the ratio of dispersive and Lorentz components of the FMR spectra (D /L ). D /L increases by increasing the temperature difference. In addition, we analyze the magnetization orientation dependence of TSTT and provide solid evidence that this dependence differs from the magnetization orientation dependence of spin-transfer torque driven by a dc bias.

  9. Giant spin-torque diode sensitivity in the absence of bias magnetic field.

    PubMed

    Fang, Bin; Carpentieri, Mario; Hao, Xiaojie; Jiang, Hongwen; Katine, Jordan A; Krivorotov, Ilya N; Ocker, Berthold; Langer, Juergen; Wang, Kang L; Zhang, Baoshun; Azzerboni, Bruno; Amiri, Pedram Khalili; Finocchio, Giovanni; Zeng, Zhongming

    2016-01-01

    Microwave detectors based on the spin-torque diode effect are among the key emerging spintronic devices. By utilizing the spin of electrons in addition to charge, they have the potential to overcome the theoretical performance limits of their semiconductor (Schottky) counterparts. However, so far, practical implementations of spin-diode microwave detectors have been limited by the necessity to apply a magnetic field. Here, we demonstrate nanoscale magnetic tunnel junction microwave detectors, exhibiting high-detection sensitivity of 75,400 mV mW(-1) at room temperature without any external bias fields, and for low-input power (micro-Watts or lower). This sensitivity is significantly larger than both state-of-the-art Schottky diode detectors and existing spintronic diodes. Micromagnetic simulations and measurements reveal the essential role of injection locking to achieve this sensitivity performance. This mechanism may provide a pathway to enable further performance improvement of spin-torque diode microwave detectors. PMID:27052973

  10. The use of skeletal extension torque in reversing Dupuytren contractures of the proximal interphalangeal joint.

    PubMed

    Agee, John M; Goss, Ben C

    2012-07-01

    Dupuytren contracture of the proximal interphalangeal (PIP) joint can be reversed by an extension torque transmitted from an external device, the Digit Widget, by skeletal pins to the middle phalanx. This extension torque, generated by the same elastic bands dentists use to align teeth, gradually restores length to soft tissues palmar to the PIP joint's axis of rotation. Simultaneously, tissues dorsal to the joint's axis will shorten toward normal length as the PIP progressively straightens. Although the contractile nodules and bands of Dupuytren disease may be excised either before or after reversal of the joint's contracture, a 2-staged approach is preferred: (1) reverse the PIP flexion contracture, and (2) excise the diseased tissue from the straightened finger. We believe this 2-staged approach yields better results. In addition, it is technically easier to avoid injury to nerves and arteries while excising the nodules and bands, when one operates through palmar skin of more nearly normal length.

  11. Experimental Robot Position Sensor Fault Tolerance Using Accelerometers and Joint Torque Sensors

    NASA Technical Reports Server (NTRS)

    Aldridge, Hal A.; Juang, Jer-Nan

    1997-01-01

    Robot systems in critical applications, such as those in space and nuclear environments, must be able to operate during component failure to complete important tasks. One failure mode that has received little attention is the failure of joint position sensors. Current fault tolerant designs require the addition of directly redundant position sensors which can affect joint design. The proposed method uses joint torque sensors found in most existing advanced robot designs along with easily locatable, lightweight accelerometers to provide a joint position sensor fault recovery mode. This mode uses the torque sensors along with a virtual passive control law for stability and accelerometers for joint position information. Two methods for conversion from Cartesian acceleration to joint position based on robot kinematics, not integration, are presented. The fault tolerant control method was tested on several joints of a laboratory robot. The controllers performed well with noisy, biased data and a model with uncertain parameters.

  12. Giant spin-torque diode sensitivity in the absence of bias magnetic field.

    PubMed

    Fang, Bin; Carpentieri, Mario; Hao, Xiaojie; Jiang, Hongwen; Katine, Jordan A; Krivorotov, Ilya N; Ocker, Berthold; Langer, Juergen; Wang, Kang L; Zhang, Baoshun; Azzerboni, Bruno; Amiri, Pedram Khalili; Finocchio, Giovanni; Zeng, Zhongming

    2016-04-07

    Microwave detectors based on the spin-torque diode effect are among the key emerging spintronic devices. By utilizing the spin of electrons in addition to charge, they have the potential to overcome the theoretical performance limits of their semiconductor (Schottky) counterparts. However, so far, practical implementations of spin-diode microwave detectors have been limited by the necessity to apply a magnetic field. Here, we demonstrate nanoscale magnetic tunnel junction microwave detectors, exhibiting high-detection sensitivity of 75,400 mV mW(-1) at room temperature without any external bias fields, and for low-input power (micro-Watts or lower). This sensitivity is significantly larger than both state-of-the-art Schottky diode detectors and existing spintronic diodes. Micromagnetic simulations and measurements reveal the essential role of injection locking to achieve this sensitivity performance. This mechanism may provide a pathway to enable further performance improvement of spin-torque diode microwave detectors.

  13. Giant spin-torque diode sensitivity in the absence of bias magnetic field

    PubMed Central

    Fang, Bin; Carpentieri, Mario; Hao, Xiaojie; Jiang, Hongwen; Katine, Jordan A.; Krivorotov, Ilya N.; Ocker, Berthold; Langer, Juergen; Wang, Kang L.; Zhang, Baoshun; Azzerboni, Bruno; Amiri, Pedram Khalili; Finocchio, Giovanni; Zeng, Zhongming

    2016-01-01

    Microwave detectors based on the spin-torque diode effect are among the key emerging spintronic devices. By utilizing the spin of electrons in addition to charge, they have the potential to overcome the theoretical performance limits of their semiconductor (Schottky) counterparts. However, so far, practical implementations of spin-diode microwave detectors have been limited by the necessity to apply a magnetic field. Here, we demonstrate nanoscale magnetic tunnel junction microwave detectors, exhibiting high-detection sensitivity of 75,400 mV mW−1 at room temperature without any external bias fields, and for low-input power (micro-Watts or lower). This sensitivity is significantly larger than both state-of-the-art Schottky diode detectors and existing spintronic diodes. Micromagnetic simulations and measurements reveal the essential role of injection locking to achieve this sensitivity performance. This mechanism may provide a pathway to enable further performance improvement of spin-torque diode microwave detectors. PMID:27052973

  14. Towards a naturalistic brain-machine interface: hybrid torque and position control allows generalization to novel dynamics.

    PubMed

    Chhatbar, Pratik Y; Francis, Joseph T

    2013-01-01

    Realization of reaching and grasping movements by a paralytic person or an amputee would greatly facilitate her/his activities of daily living. Towards this goal, control of a computer cursor or robotic arm using neural signals has been demonstrated in rodents, non-human primates and humans. This technology is commonly referred to as a Brain-Machine Interface (BMI) and is achieved by predictions of kinematic parameters, e.g. position or velocity. However, execution of natural movements, such as swinging baseball bats of different weights at the same speed, requires advanced planning for necessary context-specific forces in addition to kinematic control. Here we show, for the first time, the control of a virtual arm with representative inertial parameters using real-time neural control of torques in non-human primates (M. radiata). We found that neural control of torques leads to ballistic, possibly more naturalistic movements than position control alone, and that adding the influence of position in a hybrid torque-position control changes the feedforward behavior of these BMI movements. In addition, this level of control was achievable utilizing the neural recordings from either contralateral or ipsilateral M1. We also observed changed behavior of hybrid torque-position control under novel external dynamic environments that was comparable to natural movements. Our results demonstrate that inclusion of torque control to drive a neuroprosthetic device gives the user a more direct handle on the movement execution, especially when dealing with novel or changing dynamic environments. We anticipate our results to be a starting point of more sophisticated algorithms for sensorimotor neuroprostheses, eliminating the need of fully automatic kinematic-to-dynamic transformations as currently used by traditional kinematic-based decoders. Thus, we propose that direct control of torques, or other force related variables, should allow for more natural neuroprosthetic movements by

  15. Towards a naturalistic brain-machine interface: hybrid torque and position control allows generalization to novel dynamics.

    PubMed

    Chhatbar, Pratik Y; Francis, Joseph T

    2013-01-01

    Realization of reaching and grasping movements by a paralytic person or an amputee would greatly facilitate her/his activities of daily living. Towards this goal, control of a computer cursor or robotic arm using neural signals has been demonstrated in rodents, non-human primates and humans. This technology is commonly referred to as a Brain-Machine Interface (BMI) and is achieved by predictions of kinematic parameters, e.g. position or velocity. However, execution of natural movements, such as swinging baseball bats of different weights at the same speed, requires advanced planning for necessary context-specific forces in addition to kinematic control. Here we show, for the first time, the control of a virtual arm with representative inertial parameters using real-time neural control of torques in non-human primates (M. radiata). We found that neural control of torques leads to ballistic, possibly more naturalistic movements than position control alone, and that adding the influence of position in a hybrid torque-position control changes the feedforward behavior of these BMI movements. In addition, this level of control was achievable utilizing the neural recordings from either contralateral or ipsilateral M1. We also observed changed behavior of hybrid torque-position control under novel external dynamic environments that was comparable to natural movements. Our results demonstrate that inclusion of torque control to drive a neuroprosthetic device gives the user a more direct handle on the movement execution, especially when dealing with novel or changing dynamic environments. We anticipate our results to be a starting point of more sophisticated algorithms for sensorimotor neuroprostheses, eliminating the need of fully automatic kinematic-to-dynamic transformations as currently used by traditional kinematic-based decoders. Thus, we propose that direct control of torques, or other force related variables, should allow for more natural neuroprosthetic movements by

  16. Major Geomagnetic Storms (Dst less than or equal to -100 nT) Generated by Corotating Interaction Regions

    NASA Technical Reports Server (NTRS)

    Richardson, I. G.; Webb, D. F.; Zhang, J.; Berdichevsky, B. D.; Biesecker, D. A.; Kasper, J. C.; Kataoka, R.; Steinberg, J. T.; Thompson, B. J.; Wu, C.-C.; Zhukov, A. N.

    2006-01-01

    Seventy-nine major geomagnetic storms (minimum Dst less than or equal to -100 nT) observed in 1996 to 2004 were the focus of a Living with a Star Coordinated Data-Analysis Workshop (CDAW) in March, 2005. In 9 cases, the storm driver appears to have been purely a corotating interaction region (CIR) without any contribution from coronal mass ejection-related material (interplanetary coronal mass ejections, ICMEs). These storms were generated by structures within CIRs located both before and/or after the stream interface that included persistently southward magnetic fields for intervals of several hours. We compare their geomagnetic effects with those of 159 CIRs observed during 1996 - 2005. The major storms form the extreme tail of a continuous distribution of CIR geoeffectiveness which peaks at Dst approx. -40 nT but is subject to a prominent seasonal variation of - 40 nT which is ordered by the spring and fall equinoxes and the solar wind magnetic field direction towards or away from the Sun. The O'Brien and McPherron [2000] equations, which estimate Dst by integrating the incident solar wind electric field and incorporating a ring current loss term, largely account for the variation in storm size. They tend to underestimate the size of the larger CIR-associated storms by Dst approx. 20 nT. This suggests that injection into the ring current may be more efficient than expected in such storms. Four of the nine major storms in 1996 - 2004 occurred during a period of less than three solar rotations in September - November, 2002, also the time of maximum mean IMF and solar magnetic field intensity during the current solar cycle. The maximum CIR-storm strength found in our sample of events, plus additional 23 probable CIR-associated Dst less than or equal to -100 nT storms in 1972 - 1995, is (Dst = -161 nT). This is consistent with the maximum storm strength (Dst approx. -180 nT) expected from the O'Brien and McPherron equations for the typical range of solar wind

  17. Production Experiences with the Cray-Enabled TORQUE Resource Manager

    SciTech Connect

    Ezell, Matthew A; Maxwell, Don E; Beer, David

    2013-01-01

    High performance computing resources utilize batch systems to manage the user workload. Cray systems are uniquely different from typical clusters due to Cray s Application Level Placement Scheduler (ALPS). ALPS manages binary transfer, job launch and monitoring, and error handling. Batch systems require special support to integrate with ALPS using an XML protocol called BASIL. Previous versions of Adaptive Computing s TORQUE and Moab batch suite integrated with ALPS from within Moab, using PERL scripts to interface with BASIL. This would occasionally lead to problems when all the components would become unsynchronized. Version 4.1 of the TORQUE Resource Manager introduced new features that allow it to directly integrate with ALPS using BASIL. This paper describes production experiences at Oak Ridge National Laboratory using the new TORQUE software versions, as well as ongoing and future work to improve TORQUE.

  18. Vector control structure of an asynchronous motor at maximum torque

    NASA Astrophysics Data System (ADS)

    Chioncel, C. P.; Tirian, G. O.; Gillich, N.; Raduca, E.

    2016-02-01

    Vector control methods offer the possibility to gain high performance, being widely used. Certain applications require an optimum control in limit operating conditions, as, at maximum torque, that is not always satisfied. The paper presents how the voltage and the frequency for an asynchronous machine (ASM) operating at variable speed are determinate, with an accent on the method that keeps the rotor flux constant. The simulation analyses consider three load types: variable torque and speed, variable torque and constant speed, constant torque and variable speed. The final values of frequency and voltage are obtained through the proposed control schemes with one controller using the simulation language based on the Maple module. The dynamic analysis of the system is done for the case with P and PI controller and allows conclusions on the proposed method, which can have different applications, as the ASM in wind turbines.

  19. Helicopter transmission arrangements with split-torque gear trains

    NASA Technical Reports Server (NTRS)

    White, G.

    1983-01-01

    As an alternative to component development, the case for improved drive-train configuration is argued. In particular, the use of torque-splitting gear trains is proposed as a practicable means of improving the effectiveness of helicopter main gearboxes.

  20. Torque engineering in trilayer spin-hall system

    NASA Astrophysics Data System (ADS)

    Gupta, Gaurav; Jalil, Mansoor Bin Abdul; Liang, Gengchiau

    2016-02-01

    A trilayer system with perpendicularly magnetized metallic (FMM) free-layer, heavy metal (HM) with strong spin-hall effect and ferromagnetic insulating (FMI) substrate has been proposed to significantly enhance the torque acting on FMM. Its magnitude can be engineered by configuring the magnetization of the FMI. The analytical solution has been developed for four stable magnetization states (non-magnetic and magnetization along three Cartesian axes) of FMI to comprehensively appraise the anti-damping torque on FMM and the Gain factor. It is shown that the proposed system has much larger gain and torque compared to a bilayer system (or a trilayer system with non-magnetic substrate). The performance improvement may be extremely large for system with a thin HM. Device optimization is shown to be non-trivial and various constraints have been explained. These results would enable design of more efficient spin-orbit torque memories and logic with faster switching at yet lower current.

  1. Estimation of Coriolis Force and Torque Acting on Ares-1

    NASA Technical Reports Server (NTRS)

    Mackey, Ryan M.; Kulikov, Igor K.; Smelyanskiy, Vadim; Luchinsky, Dmitry; Orr, Jeb

    2011-01-01

    A document describes work on the origin of Coriolis force and estimating Coriolis force and torque applied to the Ares-1 vehicle during its ascent, based on an internal ballistics model for a multi-segmented solid rocket booster (SRB).

  2. Fill-in binary loop pulse-torque quantizer

    NASA Technical Reports Server (NTRS)

    Lory, C. B.

    1975-01-01

    Fill-in binary (FIB) loop provides constant heating of torque generator, an advantage of binary current switching. At the same time, it avoids mode-related dead zone and data delay of binary, an advantage of ternary quantization.

  3. Improvement on output torque of dielectric elastomer minimum energy structures

    NASA Astrophysics Data System (ADS)

    Zhao, Jianwen; Niu, Junyang; McCoul, David; Ge, Yong; Pei, Qibing; Liu, Liwu; Leng, Jinsong

    2015-08-01

    The dielectric elastomer minimum energy structure (DEMES) can realize large angular deformations by a small voltage-induced strain of the dielectric elastomer (DE), so it is a suitable candidate to make a rotary joint for a soft robot. However, the payload capacity of a DEMES joint is small compared with other types of dielectric elastomer actuators. Stacking layers of pre-strained DE thin films can increase the output torque of DEMES, but greater driving power will be needed, limiting application in mobile or flying soft robots. In this paper, based on static analysis, a design of DEMES is proposed that has larger torque than the traditional design with the same number of layers of dielectric elastomer. As an experimental example, the torque of the film with the improved design is larger than 1.7 times that of the traditional design. Experiments validate the theoretical analysis and demonstrate the improvement of DEMES output torque.

  4. Spin–torque generator engineered by natural oxidation of Cu

    PubMed Central

    An, Hongyu; Kageyama, Yuito; Kanno, Yusuke; Enishi, Nagisa; Ando, Kazuya

    2016-01-01

    The spin Hall effect is a spin–orbit coupling phenomenon, which enables electric generation and detection of spin currents. This relativistic effect provides a way for realizing efficient spintronic devices based on electric manipulation of magnetization through spin torque. However, it has been believed that heavy metals are indispensable for the spin–torque generation. Here we show that the spin Hall effect in Cu, a light metal with weak spin–orbit coupling, is significantly enhanced through natural oxidation. We demonstrate that the spin–torque generation efficiency of a Cu/Ni81Fe19 bilayer is enhanced by over two orders of magnitude by tuning the surface oxidation, reaching the efficiency of Pt/ferromagnetic metal bilayers. This finding illustrates a crucial role of oxidation in the spin Hall effect, opening a route for engineering the spin–torque generator by oxygen control and manipulating magnetization without using heavy metals. PMID:27725654

  5. Spin-torque generator engineered by natural oxidation of Cu

    NASA Astrophysics Data System (ADS)

    An, Hongyu; Kageyama, Yuito; Kanno, Yusuke; Enishi, Nagisa; Ando, Kazuya

    2016-10-01

    The spin Hall effect is a spin-orbit coupling phenomenon, which enables electric generation and detection of spin currents. This relativistic effect provides a way for realizing efficient spintronic devices based on electric manipulation of magnetization through spin torque. However, it has been believed that heavy metals are indispensable for the spin-torque generation. Here we show that the spin Hall effect in Cu, a light metal with weak spin-orbit coupling, is significantly enhanced through natural oxidation. We demonstrate that the spin-torque generation efficiency of a Cu/Ni81Fe19 bilayer is enhanced by over two orders of magnitude by tuning the surface oxidation, reaching the efficiency of Pt/ferromagnetic metal bilayers. This finding illustrates a crucial role of oxidation in the spin Hall effect, opening a route for engineering the spin-torque generator by oxygen control and manipulating magnetization without using heavy metals.

  6. Intrinsic spin torque without spin-orbit coupling

    PubMed Central

    Kim, Kyoung-Whan; Lee, Kyung-Jin; Lee, Hyun-Woo; Stiles, M. D.

    2016-01-01

    We derive an intrinsic contribution to the non-adiabatic spin torque for non-uniform magnetic textures. It differs from previously considered contributions in several ways and can be the dominant contribution in some models. It does not depend on the change in occupation of the electron states due to the current flow but rather is due to the perturbation of the electronic states when an electric field is applied. Therefore it should be viewed as electric-field-induced rather than current-induced. Unlike previously reported non-adiabatic spin torques, it does not originate from extrinsic relaxation mechanisms nor spin-orbit coupling. This intrinsic non-adiabatic spin torque is related by a chiral connection to the intrinsic spin-orbit torque that has been calculated from the Berry phase for Rashba systems. PMID:26877628

  7. Measurement of Spin Torques in WTe2/Ferromagnet Bilayers

    NASA Astrophysics Data System (ADS)

    MacNeill, David; Stiehl, Gregory M.; Guimarães, Marcos H. D.; Park, Jiwoong; Ralph, Daniel C.

    WTe2 is a semimetallic transition metal dichalcogenide (TMD) stable in the Td crystal structure. The strong spin-orbit coupling, metallic conduction, and crystalline layered structure of the material make it interesting for both fundamental and applied spintronics research, but measurements of the spin transport properties (e.g., the spin Hall conductivity) are lacking. Here we report measurements of current induced spin torques in WTe2/Ferromagnet bilayers, detected using spin torque ferromagnetic resonance. We will attempt to distinguish whether these torques arise from interfacial spin-orbit coupling or the spin Hall effect in the TMD. We study these torques as a function of TMD layer number, from bulk to few-layer, and correlate our results with layer-number dependent charge transport measurements.

  8. Macroscopic response of particle-reinforced elastomers subjected to prescribed torques or rotations on the particles

    NASA Astrophysics Data System (ADS)

    Siboni, Morteza H.; Ponte Castañeda, Pedro

    2016-06-01

    Particle-reinforced rubbers are composite materials consisting of randomly distributed, stiff fibers/particles in a soft elastomeric material. Since the particles are stiff compared to the embedding rubber, their deformation can be ignored for all practical purposes. However, due to the softness of the rubber, they can undergo rigid body translations and rotations. Constitutive models accounting for the effect of such particle motions on the macroscopic response under prescribed deformations on the boundary have been developed recently. But, in some applications (e.g., magneto-active elastomers), the particles may experience additional torques as a consequence of an externally applied (magnetic) field, which, in turn, can affect the overall rotation of the particles in the rubber, and therefore also the macroscopic response of the composite. This paper is concerned with the development of constitutive models for particle-reinforced elastomers, which are designed to account for externally applied torques on the internally distributed particles, in addition to the externally applied deformation on the boundary of the composite. For this purpose, we propose a new variational framework involving suitably prescribed eigenstresses on the particles. For simplicity, the framework is applied to an elastomer reinforced by aligned, rigid, cylindrical fibers of elliptical cross section, which can undergo finite rotations in the context of a finite-deformation, plane strain problem for the composite. In particular, expressions are derived for the average in-plane rotation of the fibers as a function of the torques that are applied on them, both under vanishing and prescribed strain on the boundary. The results of this work will make possible the development of improved constitutive models for magneto-active elastomers, and other types of smart composite materials that are susceptible to externally applied torques.

  9. Direct shaft torque measurements in a transient turbine facility

    NASA Astrophysics Data System (ADS)

    Beard, Paul F.; Povey, Thomas

    2011-03-01

    This paper describes the development and implementation of a shaft torque measurement system for the Oxford Turbine Research Facility (formerly the Turbine Test Facility (TTF) at QinetiQ, Farnborough), or OTRF. As part of the recent EU TATEF II programme, the facility was upgraded to allow turbine efficiency measurements to be performed. A shaft torque measurement system was developed as part of this upgrade. The system is unique in that, to the authors' knowledge, it provided the first direct measurement of shaft torque in a transient turbine facility although the system has wider applicability to rotating test facilities in which power measurement is a requirement. The adopted approach removes the requirement to quantify bearing friction, which can be difficult to accurately calibrate under representative operating conditions. The OTRF is a short duration (approximately 0.4 s run time) isentropic light-piston facility capable of matching all of the non-dimensional parameters important for aerodynamic and heat studies, namely Mach number, Reynolds number, non-dimensional speed, stage pressure ratio and gas-to-wall temperature ratio. The single-stage MT1 turbine used for this study is a highly loaded unshrouded design, and as such is relevant to modern military, or future civil aero-engine design. Shaft torque was measured directly using a custom-built strain gauge-based torque measurement system in the rotating frame of reference. This paper describes the development of this measurement system. The system was calibrated, including the effects of temperature, to a traceable primary standard using a purpose-built facility. The bias and precision uncertainties of the measured torque were ±0.117% and ±0.183%, respectively. To accurately determine the shaft torque developed by a turbine in the OTRF, small corrections due to inertial torque (associated with changes in the rotational speed) and aerodynamic drag (windage) are required. The methods for performing these

  10. Results and Analysis from Space Suit Joint Torque Testing

    NASA Technical Reports Server (NTRS)

    Matty, Jennifer

    2010-01-01

    This joint mobility KC lecture included information from two papers, "A Method for and Issues Associated with the Determination of Space Suit Joint Requirements" and "Results and Analysis from Space Suit Joint Torque Testing," as presented for the International Conference on Environmental Systems in 2009 and 2010, respectively. The first paper discusses historical joint torque testing methodologies and approaches that were tested in 2008 and 2009. The second paper discusses the testing that was completed in 2009 and 2010.

  11. Orion - Super Koropon(Registered Trademark) Torque/Tension Report

    NASA Technical Reports Server (NTRS)

    Hemminger, Edgar G.; McLeod, Christopher; Peil, John

    2012-01-01

    The primary objective of this testing was to obtain torque tension data for the use of Super Koropon Primer Base which was proposed for use on the Orion project. This compound is a corrosion inhibitor/sealer used on threaded fasteners and inserts as specified per NASA/JSC PRC-4004, Sealing of Joints and Faying Surfaces. Some secondary objectives of this testing, were to identify the effect on torque coefficient of several variables. This document contains the outcome of the testing.

  12. Heat Control via Torque Control in Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Venable, Richard; Colligan, Kevin; Knapp, Alan

    2004-01-01

    In a proposed advance in friction stir welding, the torque exerted on the workpiece by the friction stir pin would be measured and controlled in an effort to measure and control the total heat input to the workpiece. The total heat input to the workpiece is an important parameter of any welding process (fusion or friction stir welding). In fusion welding, measurement and control of heat input is a difficult problem. However, in friction stir welding, the basic principle of operation affords the potential of a straightforward solution: Neglecting thermal losses through the pin and the spindle that supports it, the rate of heat input to the workpiece is the product of the torque and the speed of rotation of the friction stir weld pin and, hence, of the spindle. Therefore, if one acquires and suitably processes data on torque and rotation and controls the torque, the rotation, or both, one should be able to control the heat input into the workpiece. In conventional practice in friction stir welding, one uses feedback control of the spindle motor to maintain a constant speed of rotation. According to the proposal, one would not maintain a constant speed of rotation: Instead, one would use feedback control to maintain a constant torque and would measure the speed of rotation while allowing it to vary. The torque exerted on the workpiece would be estimated as the product of (1) the torque-multiplication ratio of the spindle belt and/or gear drive, (2) the force measured by a load cell mechanically coupled to the spindle motor, and (3) the moment arm of the load cell. Hence, the output of the load cell would be used as a feedback signal for controlling the torque (see figure).

  13. Spin transfer torques in the nonlocal lateral spin valve.

    PubMed

    Xu, Yuan; Xia, Ke; Ma, Zhongshui

    2008-06-11

    We report a theoretical study on the spin and electron transport in the nonlocal lateral spin valve with a non-collinear magnetic configuration. The nonlocal magnetoresistance, defined as the voltage difference on the detection lead over the injected current, is derived analytically. The spin transfer torques on the detection lead are calculated. It is found that spin transfer torques are symmetrical for parallel and antiparallel magnetic configurations, in contrast to that in a conventional sandwiched spin valve. PMID:21825793

  14. Locating the open-closed boundary during the passage of a corotating interaction region

    NASA Astrophysics Data System (ADS)

    Urban, K. D.; Gerrard, A. J.; Lanzerotti, L. J.; Weatherwax, A. T.

    2014-12-01

    During the 2007-2009 solar quiet period there existed a unique opportunity to study the synoptic variability of the open-closed boundary (OCB) using data provided by fluxgate magnetometers located at South Pole, McMurdo, and from a network of Automatic Geophysical Observatories distributed across the Antarctic continent. In Urban et al [2011], this synoptic variability was analyzed during a geomagnetic quiet period of early August 2008 and excellent (>83%) agreement was found between the experimental observations and the BATSRUS space weather model. In this paper we discuss the OCB's synoptic behavior under the forcing of a geomagnetic storm driven by a corotating interaction region and again compare these results to predictions made with different versions of BATSRUS model runs. Strictly adhering to the method developed in Urban et al [2011], we show only weak agreement between the experimental data and model during this geomagnetically-active time, independent of the model resolution and the incorporation of the Rice Convection Model. Given that a potential source of disagreement could be from the rigidity of the original open/closed field line determination technique itself (developed for geomagnetic quiescence), we adapt the technique to variations in local time and geomagnetic activity; any remaining discrepancies between the data and the model are investigated with DMSP spacecraft-determined boundary data.

  15. Acceleration of Pickup Ions between the Magnetically-Connected Corotating Interaction Regions

    NASA Astrophysics Data System (ADS)

    Tsubouchi, K.

    2014-12-01

    We perform hybrid simulations to investigate the acceleration process of pickup ions (PUIs) at corotating interaction regions (CIRs) bounded by forward and reverse shocks. It has conventionally been supposed that PUIs accelerate in the direction of the motional electric field along the shock surface via a shock-drift or shock-surfing process. In contrast, we identify a different process that the efficient PUI acceleration takes place in the field-aligned component, as long as the magnetic field is oblique to the shock. This is due to the magnetic mirror effect at the shock, indicating adiabatic acceleration. The PUIs accelerated via this process are reflected back toward the shock upstream. These reflected energetic PUIs can move back and forth along the magnetic field between a pair of CIRs that are magnetically connected. The PUIs are repeatedly accelerated in each reflection, leading to a maximum energy gain close to 100 keV. The results are partly consistent with the observations recently reported by Wu et al. (2014). Furthermore, this mechanism well accounts for the "preacceleration" for the generation of ACRs.

  16. An MHD simulation model of time-dependent co-rotating solar wind

    NASA Astrophysics Data System (ADS)

    Hayashi, K.

    2012-08-01

    We present a treatment of observation-based time-dependent boundary conditions for the inner boundary sphere in the time-dependent three-dimensional MHD simulations of the global solar wind. With this boundary treatment, we obtain super-Alfvenic MHD solutions of time-dependent co-rotating solar wind structures. The boundary variables on the inner boundary sphere, at 50 solar radii in this study, are assumed to change linearly from one instant to the next. A new feature is that, in order to maintain the divergence-free condition of the magnetic field, the changes of the time-dependent boundary magnetic field are expressed as the potential field in a thin shell volume. The solar magnetic field data from the Wilcox Solar Observatory (WSO) and the solar wind speed data from the interplanetary scintillation (IPS) observations at Nagoya University, Japan, are used as the input boundary data. The solar wind simulated with the time-dependent boundary condition is compared with the near-Earth and Ulysses in situ measurement data and the solar wind simulated with the fixed boundary condition over a 7-month period in 1991. Reasonable agreements with the in situ measurements are obtained. The differences between the two simulations in the interplanetary field line paths are significant. The three-dimensional time-dependent MHD solution of the global solar wind will help enhance space weather models and other fields in heliophysics.

  17. The changing phases of extrasolar planet CoRoT-1b.

    PubMed

    Snellen, Ignas A G; de Mooij, Ernst J W; Albrecht, Simon

    2009-05-28

    Hot Jupiters are a class of extrasolar planet that orbit their parent stars at very short distances. They are expected to be tidally locked, which can lead to a large temperature difference between their daysides and nightsides. Infrared observations of eclipsing systems have yielded dayside temperatures for a number of transiting planets. The day-night contrast of the transiting extrasolar planet HD 189733b was 'mapped' using infrared observations. It is expected that the contrast between the daysides and nightsides of hot Jupiters is much higher at visual wavelengths, shorter than that of the peak emission, and could be further enhanced by reflected stellar light. Here we report the analysis of optical photometric data obtained over 36 planetary orbits of the transiting hot Jupiter CoRoT-1b. The data are consistent with the nightside hemisphere of the planet being entirely black, with the dayside flux dominating the optical phase curve. This means that at optical wavelengths the planet's phase variation is just as we see it for the interior planets in the Solar System. The data allow for only a small fraction of reflected light, corresponding to a geometric albedo of <0.20.

  18. Vortex dynamics studies in supersonic flow: Merging of co-rotating streamwise vortices

    NASA Astrophysics Data System (ADS)

    Maddalena, L.; Vergine, F.; Crisanti, M.

    2014-04-01

    For air-breathing propulsion systems intended for flight at very high Mach numbers, combustion is carried out at supersonic velocities and the process is mixing limited. Substantial increase in mixing rates can be obtained by fuel injection strategies centered on generating selected modes of supersonic, streamwise vortex interactions. Despite the recognized importance, and potential of the role of streamwise vortices for supersonic mixing enhancement, only few fundamental studies on their dynamics and interactions have been conducted, leaving the field largely unexplored. A reduced order model that allows the dynamics of complex, interacting, supersonic vortical structures to be investigated, is presented in this work. The prediction of the evolution of mutually interacting streamwise vortices represents an enabling element for the initiation of an effective, systematic experimental study of selected cases of interest, and is an important step toward the design of new fuel injection strategies for supersonic combustors. The case presented in this work is centered on a merging process of co-rotating vortices, and the subsequent evolution of a system composed of two counter-rotating vortex pairs. This interaction was studied, initially, with the proposed model, and was chosen for the peculiarity of the resulting morphology of the vorticity field. These results were used to design an experimental investigation with the intent to target the same specific complex flow physics. The experiment revealed the same peculiar features encountered in the simulation.

  19. Enhanced atmospheric oxygen outflow on Earth and Mars driven by a corotating interaction region

    NASA Astrophysics Data System (ADS)

    Wei, Y.; Fraenz, M.; Dubinin, E.; Woch, J.; Lühr, H.; Wan, W.; Zong, Q.-G.; Zhang, T. L.; Pu, Z. Y.; Fu, S. Y.; Barabash, S.; Lundin, R.; Dandouras, I.

    2012-03-01

    Solar wind controls nonthermal escape of planetary atmospheric volatiles, regardless of the strength of planetary magnetic fields. For both Earth with a strong dipole and Mars with weak remnant fields, the oxygen ion (O+) outflow has been separately found to be enhanced during corotating interaction region (CIR) passage. Here we compared the enhancements of O+ outflow on Earth and Mars driven by a CIR in January 2008, when Sun, Earth, and Mars were approximately aligned. The CIR propagation was recorded by STEREO, ACE, Cluster, and Mars Express (MEX). During the CIR passage, Cluster observed enhanced flux of upwelling oxygen ions above the Earth's polar region, while MEX detected an increased escape flux of oxygen ions in the Martian magnetosphere. We found that (1) under a solar wind dynamic pressure increase of 2-3 nPa, the rate of increase in Martian O+ outflow flux was 1 order higher than those on Earth; and (2) as a response to the same part of the CIR body, the rate of increase in Martian O+ outflow flux was on the same order as for Earth. The comparison results imply that the dipole effectively prevents coupling of solar wind kinetic energy to planetary ions, and the distance to the Sun is also crucially important for planetary volatile loss in our inner solar system.

  20. Unveiling stellar magnetic activity using CoRoT seismic observations

    NASA Astrophysics Data System (ADS)

    Mathur, Savita; García, Rafael A.; Salabert, David; Ballot, Jerôme; Régulo, Clara; Metcalfe, Travis S.; Baglin, Annie

    2011-01-01

    It is well known that in the Sun, the frequencies and amplitudes of acoustic modes vary throughout the solar cycle. Indeed, while the magnetic activity goes towards its maximum, the frequencies of the modes increase and their amplitudes decrease. We have analyzed data from the CoRoT mission on a few stars that exhibit solar-like oscillations. The study of HD49933 (observed during 60 days and 137 days spanning a total of 400 days) showed a modulation of the maximum amplitude per radial mode and the frequency shifts of the modes, showing magnetic activity in this rapidly rotating star. Moreover, both properties vary in an anticorrelated way and the data allowed us to establish a lower limit for the activity-cycle period of 120 days. Measurements in Ca H and K lines confirmed that this star is in the "active stars" category. We will also discuss the results obtained for other targets such as HD181420 and HD49835 for which we have investigated a similar behavior.

  1. Perpendicular Transport of Low-Energy Corotating Interaction Region--associated Nuclei

    NASA Astrophysics Data System (ADS)

    Dwyer, J. R.; Mason, G. M.; Mazur, J. E.; Jokipii, J. R.; von Rosenvinge, T. T.; Lepping, R. P.

    1997-11-01

    We present compelling observational evidence for substantial transport of energetic charged particles across the local average magnetic field. Using data from the STEP/EPACT instrument on board the Wind spacecraft, we find that during three intense corotating interaction region (CIR) events, for periods greater than 12 hr, the observed anisotropy of the particle intensity at 1 AU is often directed at a significant angle to the measured magnetic field direction, which implies significant transport across the local magnetic field. A simple diffusion model is found to fit the three events very well with a large inferred κ⊥/κ∥. For example, for 80-154 keV nucleon-1 helium, we find that κ⊥/κ∥=1.47+/-0.07, κ⊥/κ∥=0.13+/-0.02, and κ⊥/κ∥=0.45+/-0.05 for the most intense periods of the three events. We believe that this is the first direct, quantitative measurement in space of large cross-field particle transport, utilizing simultaneous measurements of the streaming particle flux, the solar wind velocity and the magnetic field direction.

  2. Galactic Cosmic-Ray Intensity Modulation by Corotating Interaction Region Stream Interfaces at 1 au

    NASA Astrophysics Data System (ADS)

    Guo, X.; Florinski, V.

    2016-07-01

    We present a new model that couples galactic cosmic-ray (GCR) propagation with magnetic turbulence transport and the MHD background evolution in the heliosphere. The model is applied to the problem of the formation of corotating interaction regions (CIRs) during the last solar minimum from the period between 2007 and 2009. The numerical model simultaneously calculates the large-scale supersonic solar wind properties and its small-scale turbulent content from 0.3 au to the termination shock. Cosmic rays are then transported through the background, and thus computed, with diffusion coefficients derived from the solar wind turbulent properties, using a stochastic Parker approach. Our results demonstrate that GCR variations depend on the ratio of diffusion coefficients in the fast and slow solar winds. Stream interfaces inside the CIRs always lead to depressions of the GCR intensity. On the other hand, heliospheric current sheet (HCS) crossings do not appreciably affect GCR intensities in the model, which is consistent with the two observations under quiet solar wind conditions. Therefore, variations in diffusion coefficients associated with CIR stream interfaces are more important for GCR propagation than the drift effects of the HCS during a negative solar minimum.

  3. Corotating interaction regions during the recent solar minimum: The power and limitations of global MHD modeling

    NASA Astrophysics Data System (ADS)

    Riley, Pete; Linker, Jon A.; Lionello, R.; Mikic, Z.

    2012-07-01

    The declining phase of solar activity cycle 23 has provided an unprecedented opportunity to study the evolution and properties of corotating interaction regions (CIRs) during unique and relatively steady conditions. The absence of significant transient activity has allowed modelers to test ambient solar wind models, but has also challenged them to reproduce structure that was qualitatively different than had been observed previously (at least within the space era). In this study, we present and analyze global magnetohydrodynamic (MHD) solutions of the inner heliosphere (from 1RS to 1 AU) for several intervals defined as part of a Center for Integrated Space weather Modeling (CISM) interdisciplinary campaign study, and, in particular, Carrington rotation 2060. We compare in situ measurements from ACE and STEREO A and B with the model results to illustrate both the capabilities and limitations of current numerical techniques. We show that, overall, the models do capture the essential structural features of the solar wind for specific time periods; however, there are times when the models and observations diverge. We describe, and, to some extent assess the sources of error in the modeling chain from the input photospheric magnetograms to the numerical schemes used to propagate structure through the heliosphere, and speculate on how they may be resolved, or at least mitigated in the future.

  4. Observations of energetic particles between a pair of corotating interaction regions

    SciTech Connect

    Wu, Z.; Chen, Y.; Tang, C. L.; Li, G.; Zhao, L. L.; Ebert, R. W.; Desai, M. I.; Mason, G. M.; Lavraud, B.; Sauvaud, J.; Zhao, L.; Landi, E.; Liu, Y. C.-M.; Guo, F.

    2014-01-20

    We report observations of the acceleration and trapping of energetic ions and electrons between a pair of corotating interaction regions (CIRs). The event occurred in Carrington Rotation 2060. Observed by the STEREO-B spacecraft, the two CIRs were separated by less than 5 days. In contrast to other CIR events, the fluxes of the energetic ions and electrons in this event reached their maxima between the trailing edge of the first CIR and the leading edge of the second CIR. The radial magnetic field (B{sub r} ) reversed its sense and the anisotropy of the flux also changed from Sunward to anti-Sunward between the two CIRs. Furthermore, there was an extended period of counterstreaming suprathermal electrons between the two CIRs. Similar observations for this event were also obtained with the Advanced Composition Explorer and STEREO-A. We conjecture that these observations were due to a U-shaped, large-scale magnetic field topology connecting the reverse shock of the first CIR and the forward shock of the second CIR. Such a disconnected U-shaped magnetic field topology may have formed due to magnetic reconnection in the upper corona.

  5. Abundance and Source Population of Suprathermal Heavy Ions in Corotating Interaction Regions

    NASA Astrophysics Data System (ADS)

    Jensema, R. J.; Desai, M. I.; Broiles, T. W.; Dayeh, M. A.

    2015-12-01

    In this study we analyze the abundances of suprathermal heavy ions in 75 Corotating Interaction Region (CIR) events between January 1st 1995 and December 31st 2008. We correlate the heavy ion abundances in these CIRs with those measured in the solar wind and suprathermal populations upstream of these events. Our analysis reveals that the CIR suprathermal heavy ion abundances vary by nearly two orders of magnitude over the solar activity cycle, with higher abundances (e.g., Fe/O) occurring during solar maximum and depleted values occurring during solar minimum. The abundances are also energy dependent, with larger abundances at higher energies, particularly during solar maximum. Following the method used by Mason et al. 2008, we correlate the CIR abundances with the corresponding solar wind and suprathermal values measured during 6-hour intervals for upstream periods spanning 10 days prior to the start of each CIR event. This correlation reveals that suprathermal heavy ions are better correlated with upstream suprathermal abundances measured at the same energy compared with the solar wind heavy ion abundances. Using the 6-hour averaging method, we also identified timeframes of maximum correlation between the CIR and the upstream suprathermal abundances, and find that the time of maximum correlation depends on the energy of the suprathermal ions. We discuss the implications of these results in terms of previous studies of CIR and suprathermal particles, and CIR seed populations and acceleration mechanisms.

  6. Relativistic electron flux dropouts in the outer radiation belt associated with corotating interaction regions

    NASA Astrophysics Data System (ADS)

    Yuan, C.-J.; Zong, Q.-G.; Wan, W.-X.; Zhang, H.; Du, A.-M.

    2015-09-01

    Understanding how the relativistic electron fluxes drop out in the outer radiation belt under different conditions is of great importance. To investigate which mechanisms may affect the dropouts under different solar wind conditions, 1.5-6.0 MeV electron flux dropout events associated with 223 corotating interaction regions (CIRs) from 1994 to 2003 are studied using the observations of Solar, Anomalous, Magnetospheric Particle Explorer satellite. According to the superposed epoch analysis, it is found that high solar wind dynamic pressure with the peak median value of about 7 nPa is corresponding to the dropout of the median of the radiation belt content (RBC) index to 20% of the level before stream interface arrival, whereas low dynamic pressure with the peak median value of about 3 nPa is related to the dropout of the median of RBC index to 40% of the level before stream interface arrival. Furthermore, the influences of Russell-McPherron effect with respect to interplanetary magnetic field orientation on dropouts are considered. It is pointed out that under positive Russell-McPherron effect (+RM effect) condition, the median of RBC index can drop to 23% of the level before stream interface arrival, while for negative Russell-McPherron effect (-RM effect) events, the median of RBC index only drops to 37% of the level before stream interface arrival. From the evolution of phase space density profiles, the effect of +RM on dropouts can be through nonadiabatic loss.

  7. The physics of pressure variation in microchannels within corotating or static discs

    NASA Astrophysics Data System (ADS)

    Guha, Abhijit; Sengupta, Sayantan

    2016-10-01

    We formulate a comprehensive analysis for the radial pressure variation in flow through microchannels within corotating (or static) discs, which is important for its fundamental value and application potential in macrofluidic and microfluidic devices. The uniqueness and utility of the present approach emanate from our ability to describe the physics completely in terms of non-dimensional numbers and to determine quantitatively the separate roles of inertia, centrifugal force, Coriolis force, and viscous effects in the overall radial pressure difference (Δpio). It is established here that the aspect ratio (ratio of inter-disc spacing and disc radius) plays only a secondary role as an independent parameter, its major role being contained within a newly identified dynamic similarity number (Ds). For radial inflow, it is shown that the magnitude of Δpio decreases monotonically as the tangential speed ratio (γ) increases but exhibits a minima when Ds is varied. For radial outflow, it is shown that Δpio increases monotonically as the flow coefficient (ϕ) decreases but evinces a maxima when Ds is varied. It is further shown that for the radial inflow case, the minima in the magnitude of Δpio exist even when the rotational speed of the discs is reduced to zero (static discs). The demonstrated existence of these extrema (i.e., minima for radial inflow and maxima for radial outflow) creates the scope for device optimization.

  8. THE THREE-DIMENSIONAL MORPHOLOGY OF A COROTATING INTERACTION REGION IN THE INNER HELIOSPHERE

    SciTech Connect

    Wood, B. E.; Howard, R. A.; Thernisien, A.; Socker, D. G. E-mail: russ.howard@nrl.navy.mil E-mail: dennis.socker@nrl.navy.mil

    2010-01-10

    In its three years of operation, the HI2 imagers on the two Solar TErrestrial RElations Observatory (STEREO) spacecraft have imaged many corotating interaction regions (CIRs) in the interplanetary medium, allowing the study of their three-dimensional (3D) morphology. Using an entirely empirical analysis technique, we construct a 3D model of one CIR, which is able to reproduce the general appearance and evolution of the CIR in HI2 images. The model CIR is also consistent with in situ data. Its curvature is compatible with the observed speed of the slow wind that is acting as the barrier for the fast wind piling up against it, and the width of the model CIR is consistent with the duration of the observed density pulse. Perpendicular to the equatorial plane, the model CIR has a parabolic shape that maps beautifully back to a bifurcated streamer observed at the Sun, which surrounds a coronal hole. This implies that this particular CIR is due to fast wind emanating from low latitudes that is impinging against slow wind in overlying streamers.

  9. Possible detection of phase changes from the non-transiting planet HD 46375b by CoRoT

    NASA Astrophysics Data System (ADS)

    Gaulme, P.; Vannier, M.; Guillot, T.; Mosser, B.; Mary, D.; Weiss, W. W.; Schmider, F.-X.; Bourguignon, S.; Deeg, H. J.; Régulo, C.; Aigrain, S.; Schneider, J.; Bruntt, H.; Deheuvels, S.; Donati, J.-F.; Appourchaux, T.; Auvergne, M.; Baglin, A.; Baudin, F.; Catala, C.; Michel, E.; Samadi, R.

    2010-07-01

    Context. The present work deals with the detection of phase changes in an exoplanetary system. HD 46375 is a solar analog known to host a non-transiting Saturn-mass exoplanet with a 3.0236 day period. It was observed by the CoRoT satellite for 34 days during the fall of 2008. Aims: We attempt to identify at optical wavelengths, the changing phases of the planet as it orbits its star. We then try to improve the star model by means of a seismic analysis of the same light curve and the use of ground-based spectropolarimetric observations. Methods: The data analysis relies on the Fourier spectrum and the folding of the time series. Results: We find evidence of a sinusoidal signal compatible in terms of both amplitude and phase with light reflected by the planet. Its relative amplitude is Δ Fp/Fstar = [13.0, 26.8] ppm, implying an albedo A = [0.16, 0.33] or a dayside visible brightness temperature Tb ≃ [1880, 2030] K by assuming a radius R = 1.1 RJup and an inclination i = 45°. Its orbital phase differs from that of the radial-velocity signal by at most 2 σ_RV. However, the tiny planetary signal is strongly blended by another signal, which we attribute to a telluric signal with a 1 day period. We show that this signal is suppressed, but not eliminated, when using the time series for HD 46179 from the same CoRoT run as a reference. Conclusions: This detection of reflected light from a non-transiting planet should be confirmable with a longer CoRoT observation of the same field. In any case, it demonstrates that non-transiting planets can be characterized using ultra-precise photometric lightcurves with present-day observations by CoRoT and Kepler. The combined detection of solar-type oscillations on the same targets (Gaulme et al. 2010a) highlights the overlap between exoplanetary science and asteroseismology and shows the high potential of a mission such as Plato. The CoRoT space mission, launched on 2006 December 27, was developed and is operated by the CNES, with

  10. Identifying the upper atmosphere structure of the inflated hot sub-Neptune CoRoT-24b

    NASA Astrophysics Data System (ADS)

    Juvan, Ines; Lammer, Helmut; Erkaev, Nikolai V.; Fossati, Luca; Cubillos, Patricio E.; Guenther, Eike; Odert, Petra; Kislyakova, Kristina G.; Lendl, Monika

    2016-04-01

    The CoRoT satellite mission discovered two Neptune-type planets, CoRoT-24b and CoRoT-24c, with observed transit radii of ≈3.7REarth and ≈4.9REarth and masses of ≤5.7MEarth and ≈28MEarth, respectively. From the deduced low mean densities it can be expected that their planetary cores are most likely surrounded by H2 dominated envelopes. While having very similar radii, the outer planet CoRoT-24c is at least 4.9 times more massive than its neighbour, indicating that their atmospheres can be fundamentally different. Therefore, we have investigated the upper atmosphere structure and escape rates of these two planets. We applied a hydrodynamic upper atmosphere model including heating by absorption of stellar extreme ultraviolet and X-ray (XUV) radiation, under the assumption that the observed transit radius RT is produced by Rayleigh scattering and H2-H2 collision absorption in a pure hydrogen atmosphere. This corresponds to a pressure level near 1 bar. We find an unsustainably high hydrodynamic escape rate of 1.6 × 1011 g/s for the atmosphere of CoRoT-24b. If real, such high atmospheric escape would lead to substantial mass loss from the planetary atmosphere, shrinking it to ≈2.2REarth within ≈4 Myr, which is inconsistent with the old age of the system. The solution to this discrepancy is that the observed transit radius RT must be 30-60% larger than the actual planetary radius at the 1 bar pressure level. We suggest that the observed transit radius RT is produced by absorption through scattering processes due to high altitude clouds or hazes. The Kepler satellite has discovered similar close-in low-density Neptune-type planets. We propose that it is very likely that the observed transit radii for the vast majority of these planets also differ from their actual planetary radii at the 1 bar pressure level. This would introduce a systematic bias in the measured radii and has dramatic implications in the determination of the mass-radius relation and for planet

  11. Enhanced spin orbit torques by oxygen incorporation in tungsten films

    NASA Astrophysics Data System (ADS)

    Phung, Timothy; Demasius, Kai-Uwe; Zhang, Weifeng; Hughes, Brian P.; Yang, See-Hun; Kellock, Andrew; Han, Wei; Pushp, Aakash; Parkin, Stuart S. P.

    Spin orbit torques are generated by the conversion of charge to spin currents in non-magnetic materials. The origin of these torques is of considerable debate. One of the most interesting materials is metallic tungsten for which large spin orbit torques have been found in thin films that are stabilized in the A15 (β-phase) structure. Here we report, using spin transfer torque ferromagnetic resonance, large spin Hall angles of up to ~-0.5 by incorporating oxygen into tungsten films. Whilst the incorporation of oxygen into the tungsten leads to significant changes in its microstructure and electrical resistivity, the large spin Hall angles measured are found to be remarkably insensitive to the oxygen doping level (12-44%). This invariance of the spin Hall angle with the bulk W(O) properties for higher oxygen concentrations suggests that the spin orbit torques in this system may actually be partly interfacial in origin, and induced by scattering of the electrons at the W(O) |CoFeB interface rather than from the interior of the W(O) film. Our results show an intriguing novel path towards enhanced spin orbit torques.

  12. Lunar and Solar Torques on the Oceanic Tides

    NASA Technical Reports Server (NTRS)

    Ray, Richard D.; Bills, Bruce G.; Chao, Benjamin Fong

    1998-01-01

    A general framework for calculating lunar and solar torques on the oceanic tides is developed in terms of harmonic constituents. Axial torques and their associated angular momentum and earth-rotation variations are deduced from recent satellite-altimeter and satellite-tracking tide solutions. Torques on the prograde components of the tide produce the familiar secular braking of the rotation rate. The estimated secular acceleration is approximately -1300 sec/century(sup 2) (less 4% after including atmospheric tides); the implied rate of change in the length of day is 2.28 milliseconds/century. Torques on the retrograde components of the tide produce periodic rotation variations at twice the tidal frequency. Interaction torques, e.g. solar torques on lunar tides, generate a large suite of rotation-rate variations at sums and differences of the original tidal frequencies. These are estimated for periods from 18.6 years to quarter-diurnal. At subdaily periods the angular momentum variations are 5 to 6 orders of magnitude smaller than the variations caused by ocean tidal currents.

  13. Torqued fireballs in relativistic heavy-ion collisions

    SciTech Connect

    Bozek, Piotr; Broniowski, Wojciech; Moreira, Joao

    2011-03-15

    We show that the fluctuations in the wounded-nucleon model of the initial stage of relativistic heavy-ion collisions, together with the natural assumption that the forward- (backward-) moving wounded nucleons emit particles preferably in the forward (backward) direction, lead to an event-by-event torqued fireball. The principal axes associated with the transverse shape are rotated in the forward region in the opposite direction than in the backward region. On the average, the standard deviation of the relative torque angle between the forward and backward rapidity regions is {approx}20 deg. for the central and 10 deg. for the midperipheral collisions. The hydrodynamic expansion of a torqued fireball leads to a torqued collective flow, yielding, in turn, torqued principal axes of the transverse-momentum distributions at different rapidities. We propose experimental measures, based on cumulants involving particles in different rapidity regions, which should allow for a quantitative determination of the effect from the data. To estimate the nonflow contributions from resonance decays we run Monte Carlo simulations with therminator, a thermal heavy-ion generator. If the event-by-event torque effect is found in the data, it will support the assumptions concerning the fluctuations in the early stage of the fireball formation, as well as the hypothesis of the asymmetric rapidity shape of the emission functions of the moving sources in the nucleus-nucleus collisions.

  14. Structural transitions and elasticity from torque measurements on DNA.

    PubMed

    Bryant, Zev; Stone, Michael D; Gore, Jeff; Smith, Steven B; Cozzarelli, Nicholas R; Bustamante, Carlos

    2003-07-17

    Knowledge of the elastic properties of DNA is required to understand the structural dynamics of cellular processes such as replication and transcription. Measurements of force and extension on single molecules of DNA have allowed direct determination of the molecule's mechanical properties, provided rigorous tests of theories of polymer elasticity, revealed unforeseen structural transitions induced by mechanical stresses, and established an experimental and conceptual framework for mechanical assays of enzymes that act on DNA. However, a complete description of DNA mechanics must also consider the effects of torque, a quantity that has hitherto not been directly measured in micromanipulation experiments. We have measured torque as a function of twist for stretched DNA--torsional strain in over- or underwound molecules was used to power the rotation of submicrometre beads serving as calibrated loads. Here we report tests of the linearity of DNA's twist elasticity, direct measurements of the torsional modulus (finding a value approximately 40% higher than generally accepted), characterization of torque-induced structural transitions, and the establishment of a framework for future assays of torque and twist generation by DNA-dependent enzymes. We also show that cooperative structural transitions in DNA can be exploited to construct constant-torque wind-up motors and force-torque converters.

  15. DC torque motor actuated anti-lock brake controller

    SciTech Connect

    Agarwal, P.D.; Kade, A.

    1989-02-21

    A wheel lock control system is described for limiting the brake pressure applied to the brake of a vehicle wheel traveling over a road surface, the system comprising: an actuator for controlling the brake pressure to the brake of the wheel, the actuator including a torque motor for generating a motor torque in response to motor current to control the applied brake pressure in accordance with the value of the motor torque, the motor torque having a value proportional to the value of the motor current; means for determining the tire torque tending to accelerate the wheel during the application of brake pressure; means for storing the value of motor current corresponding to the maximum determined value of tire torque; means for detecting an incipient wheel lockup condition; and means for establishing the motor current following a detected incipient wheel lockup condition at a value having a predetermined relationship to the stored value of motor current to control the brake pressure at a predetermined braking condition.

  16. On Torque and Tumbling in Swimming Escherichia coli▿ †

    PubMed Central

    Darnton, Nicholas C.; Turner, Linda; Rojevsky, Svetlana; Berg, Howard C.

    2007-01-01

    Bacteria swim by rotating long thin helical filaments, each driven at its base by a reversible rotary motor. When the motors of peritrichous cells turn counterclockwise (CCW), their filaments form bundles that drive the cells forward. We imaged fluorescently labeled cells of Escherichia coli with a high-speed charge-coupled-device camera (500 frames/s) and measured swimming speeds, rotation rates of cell bodies, and rotation rates of flagellar bundles. Using cells stuck to glass, we studied individual filaments, stopping their rotation by exposing the cells to high-intensity light. From these measurements we calculated approximate values for bundle torque and thrust and body torque and drag, and we estimated the filament stiffness. For both immobilized and swimming cells, the motor torque, as estimated using resistive force theory, was significantly lower than the motor torque reported previously. Also, a bundle of several flagella produced little more torque than a single flagellum produced. Motors driving individual filaments frequently changed directions of rotation. Usually, but not always, this led to a change in the handedness of the filament, which went through a sequence of polymorphic transformations, from normal to semicoiled to curly 1 and then, when the motor again spun CCW, back to normal. Motor reversals were necessary, although not always sufficient, to cause changes in filament chirality. Polymorphic transformations among helices having the same handedness occurred without changes in the sign of the applied torque. PMID:17189361

  17. Hubble Space Telescope EVA Multisetting Torque Limiter redesign

    NASA Astrophysics Data System (ADS)

    Richards, Paul W.; Garrah, Mike

    The Hubble Space Telescope (HST) Multisetting Torque Limiter will be used by astronauts during the First Servicing Mission STS-61. It was designed to replace several individual torque limiters. This replacement reduces the number of tools required as well as reduce the time required for servicing. The Multisetting Torque Limiter design specified five separate torque settings: 2, 5.3, 9, 35 and 45 ft-lbs. This original units were tested at the 2, 5.3, and 9 ft-lbs settings and did not meet the design specifications. The 35 ft-lb and 45 ft-lb torque settings were not incorporated into the original flight design. The objective of the Goddard Space Flight Center (GSFC) redesign effort is to incorporate all five torque settings into a flight design which means the requirements for the first HST Servicing Mission. The first target of the redesign effort focused on the spring chamber and ball detent design. The original design used belleville springs in parallel; the new design changed this configuration to belleville springs stacked in series. The current engineering unit was successfully tested in ambient environment at all five settings. A flight design will soon undergo thermal vacuum testing to evaluate its performance at the temperature extremes.

  18. From CoRoT 102899501 to the Sun. A time evolution model of chromospheric activity on the main sequence

    NASA Astrophysics Data System (ADS)

    Gondoin, P.; Gandolfi, D.; Fridlund, M.; Frasca, A.; Guenther, E. W.; Hatzes, A.; Deeg, H. J.; Parviainen, H.; Eigmüller, P.; Deleuil, M.

    2012-12-01

    Aims: The present study reports measurements of the rotation period of a young solar analogue, estimates of its surface coverage by photospheric starspots and of its chromospheric activity level, and derivations of its evolutionary status. Detailed observations of many young solar-type stars, such as the one reported in the present paper, provide insight into rotation and magnetic properties that may have prevailed on the Sun in its early evolution. Methods: Using a model based on the rotational modulation of the visibility of active regions, we analysed the high-accuracy CoRoT lightcurve of the active star CoRoT 102899501. Spectroscopic follow-up observations were used to derive its fundamental parameters. We compared the chromospheric activity level of Corot 102899501 with the R'HK index distribution vs age established on a large sample of solar-type dwarfs in open clusters. We also compared the chromospheric activity level of this young star with a model of chromospheric activity evolution established by combining relationships between the R'HK index and the Rossby number with a recent model of stellar rotation evolution on the main sequence. Results: We measure the spot coverage of the stellar surface as a function of time and find evidence for a tentative increase from 5 - 14% at the beginning of the observing run to 13-29% 35 days later. A high level of magnetic activity on Corot 102899501 is corroborated by a strong emission in the Balmer and Ca ii H and K lines (R'HK ~ -4). The starspots used as tracers of the star rotation constrain the rotation period to 1.625 ± 0.002 days and do not show evidence for differential rotation. The effective temperature (Teff = 5180 ± 80 K), surface gravity (log g = 4.35 ± 0.1), and metallicity ([M/H] = 0.05 ± 0.07 dex) indicate that the object is located near the evolutionary track of a 1.09 ± 0.12 M⊙ pre-main sequence star at an age of 23 ± 10 Myr. This value is consistent with the "gyro-age" of about 8-25 Myr

  19. Global occurrence of Torque teno virus in water systems.

    PubMed

    Charest, A J; Plummer, J D; Long, S C; Carducci, A; Verani, M; Sidhu, J P S

    2015-09-01

    Bacterial indicator organisms are used globally to assess the microbiological safety of waters. However, waterborne viral outbreaks have occurred in drinking water systems despite negative bacterial results. Using viral markers may therefore provide more accurate health risk assessment data. In this study, fecal, wastewater, stormwater, surface water (fresh and salt), groundwater, and drinking water samples were analyzed for the presence or concentration of traditional indicators, innovative indicators and viral markers. Samples were obtained in the United States, Italy, and Australia and results compared to those reported for studies conducted in Asia and South America as well. Indicators included total coliforms, Escherichia coli, enterococci, male-specific coliphages, somatic coliphages and microviradae. Viral markers included adenovirus, polyomavirus, and a potential new surrogate, Torque teno virus (TTV). TTV was more frequently found in wastewaters (38-100%) and waters influenced by waste discharges (25%) than in surface waters used as drinking water sources (5%). TTV was also specific to human rather than animal feces. While TTV numbers were strongly correlated to other viral markers in wastewaters, suggesting its utility as a fecal contamination marker, data limitations and TTV presence in treated drinking waters demonstrates that additional research is needed on this potential viral indicator.

  20. Report on Toyota/Prius Motor Torque-Capability, Torque-Property, No-Load Back EMF, and Mechanical Losses

    SciTech Connect

    Hsu, J.S.

    2004-09-30

    In today's hybrid vehicle market, the Toyota Prius drive system is currently considered the leader in electrical, mechanical, and manufacturing innovations. It is significant that in today's marketplace, Toyota is able to manufacture and sell the vehicle for a profit. This project's objective is to test the torque capability of the 2004 Prius motor and to analyze the torque properties relating to the rotor structure. The tested values of no-load back electromotive force (emf) and mechanical losses are also presented.

  1. An ultra-low power wireless sensor network for bicycle torque performance measurements.

    PubMed

    Gharghan, Sadik K; Nordin, Rosdiadee; Ismail, Mahamod

    2015-01-01

    In this paper, we propose an energy-efficient transmission technique known as the sleep/wake algorithm for a bicycle torque sensor node. This paper aims to highlight the trade-off between energy efficiency and the communication range between the cyclist and coach. Two experiments were conducted. The first experiment utilised the Zigbee protocol (XBee S2), and the second experiment used the Advanced and Adaptive Network Technology (ANT) protocol based on the Nordic nRF24L01 radio transceiver chip. The current consumption of ANT was measured, simulated and compared with a torque sensor node that uses the XBee S2 protocol. In addition, an analytical model was derived to correlate the sensor node average current consumption with a crank arm cadence. The sensor node achieved 98% power savings for ANT relative to ZigBee when they were compared alone, and the power savings amounted to 30% when all components of the sensor node are considered. The achievable communication range was 65 and 50 m for ZigBee and ANT, respectively, during measurement on an outdoor cycling track (i.e., velodrome). The conclusions indicate that the ANT protocol is more suitable for use in a torque sensor node when power consumption is a crucial demand, whereas the ZigBee protocol is more convenient in ensuring data communication between cyclist and coach. PMID:26007728

  2. An Ultra-Low Power Wireless Sensor Network for Bicycle Torque Performance Measurements

    PubMed Central

    Gharghan, Sadik K.; Nordin, Rosdiadee; Ismail, Mahamod

    2015-01-01

    In this paper, we propose an energy-efficient transmission technique known as the sleep/wake algorithm for a bicycle torque sensor node. This paper aims to highlight the trade-off between energy efficiency and the communication range between the cyclist and coach. Two experiments were conducted. The first experiment utilised the Zigbee protocol (XBee S2), and the second experiment used the Advanced and Adaptive Network Technology (ANT) protocol based on the Nordic nRF24L01 radio transceiver chip. The current consumption of ANT was measured, simulated and compared with a torque sensor node that uses the XBee S2 protocol. In addition, an analytical model was derived to correlate the sensor node average current consumption with a crank arm cadence. The sensor node achieved 98% power savings for ANT relative to ZigBee when they were compared alone, and the power savings amounted to 30% when all components of the sensor node are considered. The achievable communication range was 65 and 50 m for ZigBee and ANT, respectively, during measurement on an outdoor cycling track (i.e., velodrome). The conclusions indicate that the ANT protocol is more suitable for use in a torque sensor node when power consumption is a crucial demand, whereas the ZigBee protocol is more convenient in ensuring data communication between cyclist and coach. PMID:26007728

  3. Spin-orbit torques for current parallel and perpendicular to a domain wall

    SciTech Connect

    Schulz, Tomek; Lee, Kyujoon; Karnad, Gurucharan V.; Alejos, Oscar; Martinez, Eduardo; Moretti, Simone; Garcia, Karin; Ravelosona, Dafiné; Vila, Laurent; Lo Conte, Roberto; Kläui, Mathias; Ocker, Berthold; Brataas, Arne

    2015-09-21

    We report field- and current-induced domain wall (DW) depinning experiments in Ta\\Co{sub 20}Fe{sub 60}B{sub 20}\\MgO nanowires through a Hall cross geometry. While purely field-induced depinning shows no angular dependence on in-plane fields, the effect of the current depends crucially on the internal DW structure, which we manipulate by an external magnetic in-plane field. We show depinning measurements for a current sent parallel to the DW and compare its depinning efficiency with the conventional case of current flowing perpendicularly to the DW. We find that the maximum efficiency is similar for both current directions within the error bars, which is in line with a dominating damping-like spin-orbit torque (SOT) and indicates that no large additional torques arise for currents perpendicular to the DW. Finally, we find a varying dependence of the maximum depinning efficiency angle for different DWs and pinning levels. This emphasizes the importance of our full angular scans compared with previously used measurements for just two field directions (parallel and perpendicular to the DW) to determine the real torque strength and shows the sensitivity of the SOT to the precise DW structure and pinning sites.

  4. Acoustic radiation force and torque on an absorbing compressible particle in an inviscid fluid.

    PubMed

    Silva, Glauber T

    2014-11-01

    Exact formulas of the acoustic radiation force and torque exerted by an arbitrary time-harmonic wave on an absorbing compressible particle that is suspended in an inviscid fluid are presented. It is considered that the particle diameter is much smaller than the incident wavelength, i.e., the so-called Rayleigh scattering limit. Moreover, the particle absorption assumed here is due to the attenuation of compressional waves only. Shear waves inside and outside the particle are neglected, since the inner and outer viscous boundary layer of the particle are supposed to be much smaller than the particle radius. The obtained radiation force formulas are used to establish the trapping conditions of a particle by a single-beam acoustical tweezer based on a spherically focused ultrasound transducer. In this case, it is shown that the particle absorption has a pivotal role in single-beam trapping at the transducer focal region. Furthermore, it is found that only the first-order Bessel vortex beam can generate the radiation torque on a small particle. In addition, numerical evaluation of the radiation force and torque exerted on a benzene and an olive oil droplet suspended in water are presented and discussed. PMID:25373943

  5. Mechanoluminescence torque transducer integrated with cost-effective luminescence sensor and UV LEDs

    NASA Astrophysics Data System (ADS)

    Kim, Gi-Woo; Kim, Ji-Sik; Yun, Jong-Hwan; Cho, Min-Young

    2015-04-01

    This paper presents a preliminary study investigating the development of a new type of non-contacting torque sensor based on the mechanoluminescence (ML) of a microparticles, such as ZnS:Cu. Typically, applications of ML microparticles have been used in a stress sensor applications successfully, in which these particles are applied to realtime visualization of the stress distribution of cracks, impacts, and ML light generation. Kim et al. demonstrated their potentials of ML microparticles by successfully measuring the sinusoidal torque applied to a rotational shaft through the measurement of the ML intensity signature using a photomultiplier tube (PMT) sensor, which can be widely used in various industrial areas such as automotives, robotics, rotors, and turbines. To show their further potential applications, a cost-effective luminescence sensor and UV LEDs are integrated, and used for detecting the variation of ML intensity in this study. In addition, precision sinusoidal torque waveform with high frequency up to 15 Hz is used to investigate the frequency-dependent hysteresis phenomenon.

  6. Acoustic radiation force and torque on an absorbing compressible particle in an inviscid fluid.

    PubMed

    Silva, Glauber T

    2014-11-01

    Exact formulas of the acoustic radiation force and torque exerted by an arbitrary time-harmonic wave on an absorbing compressible particle that is suspended in an inviscid fluid are presented. It is considered that the particle diameter is much smaller than the incident wavelength, i.e., the so-called Rayleigh scattering limit. Moreover, the particle absorption assumed here is due to the attenuation of compressional waves only. Shear waves inside and outside the particle are neglected, since the inner and outer viscous boundary layer of the particle are supposed to be much smaller than the particle radius. The obtained radiation force formulas are used to establish the trapping conditions of a particle by a single-beam acoustical tweezer based on a spherically focused ultrasound transducer. In this case, it is shown that the particle absorption has a pivotal role in single-beam trapping at the transducer focal region. Furthermore, it is found that only the first-order Bessel vortex beam can generate the radiation torque on a small particle. In addition, numerical evaluation of the radiation force and torque exerted on a benzene and an olive oil droplet suspended in water are presented and discussed.

  7. Dynamic Simulation of Shipping Package Subjected to Torque Load and Sequential Impacts

    SciTech Connect

    Wu, T

    2006-04-17

    A numerical technique has been developed to simulate the structural responses of radioactive material packaging components requiring closure-tightening torque to the scenarios of the hypothetical accident conditions (HAC) defined in the Code of Federal Regulations Title 10 part 71 (10CFR 71). A rigorous solution to this type of problem poses a considerable mathematical challenge. Conventional methods for evaluating the residue stresses due to the torque load are either inaccurate or not applicable to dynamic analyses. In addition, the HAC events occur sequentially and the cumulative damage to the package needs to be evaluated. Commonly, individual HAC events are analyzed separately and the cumulative damage is not addressed. As a result, strict compliance of the package with the requirements specified in 10CFR 71 is usually demonstrated by physical testing. The proposed technique utilizes the combination of kinematic constraints, rigid-body motions and structural deformations to overcome some of the difficulties encountered in modeling the effect of cumulative damage in numerical solutions. The analyses demonstrating use of this technique were performed to determine the cumulative damage of torque preload, a 30-foot drop, a 30-foot dynamic crush and a 40-inch free fall onto a mild steel pipe.

  8. Pigeons produce aerodynamic torques through changes in wing trajectory during low speed aerial turns.

    PubMed

    Ros, Ivo G; Badger, Marc A; Pierson, Alyssa N; Bassman, Lori C; Biewener, Andrew A

    2015-02-01

    The complexity of low speed maneuvering flight is apparent from the combination of two critical aspects of this behavior: high power and precise control. To understand how such control is achieved, we examined the underlying kinematics and resulting aerodynamic mechanisms of low speed turning flight in the pigeon (Columba livia). Three birds were trained to perform 90 deg level turns in a stereotypical fashion and detailed three-dimensional (3D) kinematics were recorded at high speeds. Applying the angular momentum principle, we used mechanical modeling based on time-varying 3D inertia properties of individual sections of the pigeon's body to separate angular accelerations of the torso based on aerodynamics from those based on inertial effects. Directly measured angular accelerations of the torso were predicted by aerodynamic torques, justifying inferences of aerodynamic torque generation based on inside wing versus outside wing kinematics. Surprisingly, contralateral asymmetries in wing speed did not appear to underlie the 90 deg aerial turns, nor did contralateral differences in wing area, angle of attack, wingbeat amplitude or timing. Instead, torso angular accelerations into the turn were associated with the outside wing sweeping more anteriorly compared with a more laterally directed inside wing. In addition to moving through a relatively more retracted path, the inside wing was also more strongly pronated about its long axis compared with the outside wing, offsetting any difference in aerodynamic angle of attack that might arise from the observed asymmetry in wing trajectories. Therefore, to generate roll and pitch torques into the turn, pigeons simply reorient their wing trajectories toward the desired flight direction. As a result, by acting above the center of mass, the net aerodynamic force produced by the wings is directed inward, generating the necessary torques for turning.

  9. Insertion torque versus mechanical resistance of mini-implants inserted in different cortical thickness

    PubMed Central

    Santos, Renata de Faria; Ruellas, Antonio Carlos de Oliveira; Fernandes, Daniel Jogaib; Elias, Carlos Nelson

    2014-01-01

    Objective This study aimed to measure insertion torque, tip mechanical resistance to fracture and transmucosal neck of mini-implants (MI) (Conexão Sistemas de PróteseT), as well as to analyze surface morphology. Methods Mechanical tests were carried out to measure the insertion torque of MIs in different cortical thicknesses, and tip mechanical resistance to fracture as well as transmucosal neck of MIs. Surface morphology was assessed by scanning electron microscopy (SEM) before and after the mechanical tests. Results Values of mechanical resistance to fracture (22.14 N.cm and 54.95 N.cm) were higher and statistically different (P < 0.05) from values of insertion torque for 1-mm (7.60 N.cm) and 2-mm (13.27 N.cm) cortical thicknesses. Insertion torque was statistically similar (P > 0.05) to torsional fracture in the tip of MI (22.14 N.cm) when 3 mm cortical thickness (16.11 N.cm) and dense bone (23.95 N.cm) were used. Torsional fracture of the transmucosal neck (54.95 N.cm) was higher and statistically different (P < 0.05) from insertion torsional strength in all tested situations. SEM analysis showed that the MIs had the same smooth surface when received from the manufacturer and after the mechanical tests were performed. Additionally, no significant marks resulting from the manufacturing process were observed. Conclusion All mini-implants tested presented adequate surface morphology. The resistance of mini-implants to fracture safely allows placement in 1 and 2-mm cortical thickness. However, in 3-mm cortical thickness and dense bones, pre-drilling with a bur is recommended before insertion. PMID:25162571

  10. Pigeons produce aerodynamic torques through changes in wing trajectory during low speed aerial turns.

    PubMed

    Ros, Ivo G; Badger, Marc A; Pierson, Alyssa N; Bassman, Lori C; Biewener, Andrew A

    2015-02-01

    The complexity of low speed maneuvering flight is apparent from the combination of two critical aspects of this behavior: high power and precise control. To understand how such control is achieved, we examined the underlying kinematics and resulting aerodynamic mechanisms of low speed turning flight in the pigeon (Columba livia). Three birds were trained to perform 90 deg level turns in a stereotypical fashion and detailed three-dimensional (3D) kinematics were recorded at high speeds. Applying the angular momentum principle, we used mechanical modeling based on time-varying 3D inertia properties of individual sections of the pigeon's body to separate angular accelerations of the torso based on aerodynamics from those based on inertial effects. Directly measured angular accelerations of the torso were predicted by aerodynamic torques, justifying inferences of aerodynamic torque generation based on inside wing versus outside wing kinematics. Surprisingly, contralateral asymmetries in wing speed did not appear to underlie the 90 deg aerial turns, nor did contralateral differences in wing area, angle of attack, wingbeat amplitude or timing. Instead, torso angular accelerations into the turn were associated with the outside wing sweeping more anteriorly compared with a more laterally directed inside wing. In addition to moving through a relatively more retracted path, the inside wing was also more strongly pronated about its long axis compared with the outside wing, offsetting any difference in aerodynamic angle of attack that might arise from the observed asymmetry in wing trajectories. Therefore, to generate roll and pitch torques into the turn, pigeons simply reorient their wing trajectories toward the desired flight direction. As a result, by acting above the center of mass, the net aerodynamic force produced by the wings is directed inward, generating the necessary torques for turning. PMID:25452503

  11. Identifying the `true' radius of the hot sub-Neptune CoRoT-24b by mass-loss modelling

    NASA Astrophysics Data System (ADS)

    Lammer, H.; Erkaev, N. V.; Fossati, L.; Juvan, I.; Odert, P.; Cubillos, P. E.; Guenther, E.; Kislyakova, K. G.; Johnstone, C. P.; Lüftinger, T.; Güdel, M.

    2016-09-01

    For the hot exoplanets CoRoT-24b and CoRoT-24c, observations have provided transit radii RT of 3.7 ± 0.4R⊕ and 4.9 ± 0.5R⊕, and masses of ≤5.7M⊕ and 28 ± 11M⊕, respectively. We study their upper atmosphere structure and escape applying an hydrodynamic model. Assuming RT ≈ RPL, where RPL is the planetary radius at the pressure of 100 mbar, we obtained for CoRoT-24b unrealistically high thermally driven hydrodynamic escape rates. This is due to the planet's high temperature and low gravity, independent of the stellar EUV flux. Such high escape rates could last only for <100 Myr, while RPL shrinks till the escape rate becomes less than or equal to the maximum possible EUV-driven escape rate. For CoRoT-24b, RPL must be therefore located at ≈1.9-2.2R⊕ and high altitude hazes/clouds possibly extinct the light at RT. Our analysis constraints also the planet's mass to be 5-5.7M⊕. For CoRoT-24c, RPL and RT lie too close together to be distinguished in the same way. Similar differences between RPL and RT may be present also for other hot, low-density sub-Neptunes.

  12. DO COROTATING INTERACTION REGION ASSOCIATED SHOCKS SURVIVE WHEN THEY PROPAGATE INTO THE HELIOSHEATH?

    SciTech Connect

    Provornikova, E.; Opher, M.; Izmodenov, V.; Toth, G. E-mail: mopher@bu.edu E-mail: gtoth@umich.edu

    2012-09-10

    During the solar minimum at the distance of 42-52 AU from the Sun, Voyager 2 observed recurrent sharp, shock-like increases in the solar wind speed that look very much like forward shocks (Lazarus et al.). The shocks were produced by corotating interaction regions (CIRs) that originated near the Sun. After the termination shock (TS) crossing in 2007, Voyager 2 entered the heliosheath and has been observing the plasma emanated during the recent solar minima. Measurements show high variable flow, but there were no shocks detected in the heliosheath. When CIR-driven shocks propagate to the outer heliosphere, their structure changes due to collision and merging processes of CIRs. In this Letter, we explore an effect of the merging of CIRs on the structure of CIR-associated shocks. We use a three-dimensional MHD model to study the outward propagation of the shocks with characteristics similar to those observed by Voyager 2 at {approx}45 AU (Lazarus et al. 1999). We show that due to merging of CIRs (1) reverse shocks disappear, (2) forward shocks become weaker due to interaction with rarefaction regions from preceding CIRs, and (3) forward shocks significantly weaken in the heliosheath. Merged CIRs produce compression regions in the heliosheath with small fluctuations of plasma parameters. Amplitudes of the fluctuations diminish as they propagate deeper in the sheath. We conclude that interaction of shocks and rarefaction regions could be one of the explanations, why shocks produced by CIRs are not observed in the heliosheath by Voyager 2 while they were frequently observed upstream the TS.

  13. Solar wind interaction with comet 67P: Impacts of corotating interaction regions

    NASA Astrophysics Data System (ADS)

    Edberg, N. J. T.; Eriksson, A. I.; Odelstad, E.; Vigren, E.; Andrews, D. J.; Johansson, F.; Burch, J. L.; Carr, C. M.; Cupido, E.; Glassmeier, K.-H.; Goldstein, R.; Halekas, J. S.; Henri, P.; Koenders, C.; Mandt, K.; Mokashi, P.; Nemeth, Z.; Nilsson, H.; Ramstad, R.; Richter, I.; Wieser, G. Stenberg

    2016-02-01

    We present observations from the Rosetta Plasma Consortium of the effects of stormy solar wind on comet 67P/Churyumov-Gerasimenko. Four corotating interaction regions (CIRs), where the first event has possibly merged with a coronal mass ejection, are traced from Earth via Mars (using Mars Express and Mars Atmosphere and Volatile EvolutioN mission) to comet 67P from October to December 2014. When the comet is 3.1-2.7 AU from the Sun and the neutral outgassing rate ˜1025-1026 s-1, the CIRs significantly influence the cometary plasma environment at altitudes down to 10-30 km. The ionospheric low-energy (˜5 eV) plasma density increases significantly in all events, by a factor of >2 in events 1 and 2 but less in events 3 and 4. The spacecraft potential drops below -20 V upon impact when the flux of electrons increases. The increased density is likely caused by compression of the plasma environment, increased particle impact ionization, and possibly charge exchange processes and acceleration of mass-loaded plasma back to the comet ionosphere. During all events, the fluxes of suprathermal (˜10-100 eV) electrons increase significantly, suggesting that the heating mechanism of these electrons is coupled to the solar wind energy input. At impact the magnetic field strength in the coma increases by a factor of 2-5 as more interplanetary magnetic field piles up around the comet. During two CIR impact events, we observe possible plasma boundaries forming, or moving past Rosetta, as the strong solar wind compresses the cometary plasma environment. We also discuss the possibility of seeing some signatures of the ionospheric response to tail disconnection events.

  14. SHOCK ACCELERATION OF PARTICLES IN THE NONSTATIONARY EVOLUTION OF COROTATING INTERACTION REGIONS

    SciTech Connect

    Tsubouchi, K.

    2011-10-20

    One-dimensional hybrid simulations are used to investigate the particle energization process during the nonstationary evolution of corotating interaction regions (CIRs) in the heliosphere. The simulation model, where fast and slow solar wind streams interact with each other, allows the formation of a pair (forward/reverse) of shocks at the CIR boundaries and the stream interface interior, which prevents the interchange of both streams. While both shocks are quasi-perpendicular and are not capable of accelerating thermal particles (hundreds of eV) up to a suprathermal energy (tens to hundreds of keV) in the early phase of their development, the reverse shock in the fast wind experiences a transition to a quasi-parallel regime in the later phase. The quasi-parallel reverse shock can efficiently accelerate particles to the suprathermal range. The different timescale of the adiabatic expansion between the fast and slow wind leads to a transition of the shock geometry that can take place more easily in the reverse shock than in the forward shock, where the magnetic field in the fast wind remains more radial to the propagation direction than in the slow wind. The difference in the acceleration efficiency between these shocks follows a well-known observed asymmetry in the profile of the energetic particle fluxes, where the larger intensity increases more in the reverse shock than in the forward shock. The present results suggest that the solar wind thermal plasma, as well as interstellar pickup ions, can contribute to the composition of energetic particles associated with the CIRs.

  15. Particle acceleration at corotating interaction regions in the three-dimensional heliosphere

    SciTech Connect

    Desai, M.I.; Marsden, R.G.; Sanderson, T.R.; Balogh, A.; Forsyth, R.J.; Gosling, J.T.

    1998-02-01

    We have investigated the relationship between the energetic ({approximately}1MeV) proton intensity (J) and the magnetic compression ratio (C) measured at the trailing edges of corotating interaction regions observed at Ulysses. In general, our results show that the proton intensity was well correlated with the compression ratio, provided that the seed intensity remained constant, consistent with predictions of the Fermi model. Specifically, our results indicate that particles were accelerated to above {approximately}1MeV in energy at or near the trailing edges of the compression regions observed in the midlatitude southern heliosphere, irrespective of whether the bounding reverse shocks were present or not. On the basis of this, we conclude that shock acceleration is probably not the only mechanism by which particles are accelerated to above {approximately}1MeV in energy at compression or interaction regions (CIRs). On the basis of magnetic field measurements obtained near the trailing edges of several midlatitude CIRs, we propose that particles could have been accelerated via the Fermi mechanism by being scattered back and forth across the trailing edges of the compression regions by large-amplitude Alfv{acute e}n waves. Our results also show that the proton intensity was well correlated with the compression ratio during low solar activity periods but was essentially independent of C during periods of high solar activity. We suggest that the correlation between J and C was not observed during solar active periods because of significant variations in the seed intensity that result from sporadic contributions from transient solar events. In contrast, the correlation was observable during quiescent periods probably because contributions from transients had decreased dramatically, which allowed the CIRs to accelerate particles out of a seed population whose intensity remained relatively unperturbed. {copyright} 1998 American Geophysical Union

  16. Fuzzy Backstepping Torque Control Of Passive Torque Simulator With Algebraic Parameters Adaptation

    NASA Astrophysics Data System (ADS)

    Ullah, Nasim; Wang, Shaoping; Wang, Xingjian

    2015-07-01

    This work presents fuzzy backstepping control techniques applied to the load simulator for good tracking performance in presence of extra torque, and nonlinear friction effects. Assuming that the parameters of the system are uncertain and bounded, Algebraic parameters adaptation algorithm is used to adopt the unknown parameters. The effect of transient fuzzy estimation error on parameters adaptation algorithm is analyzed and the fuzzy estimation error is further compensated using saturation function based adaptive control law working in parallel with the actual system to improve the transient performance of closed loop system. The saturation function based adaptive control term is large in the transient time and settles to an optimal lower value in the steady state for which the closed loop system remains stable. The simulation results verify the validity of the proposed control method applied to the complex aerodynamics passive load simulator.

  17. The three dimensional structure of corotating interaction regions and modeling of the heavy ion sensor

    NASA Astrophysics Data System (ADS)

    Broiles, Thomas W.

    Corotating Interaction Regions (CIRs) are compression regions that form in interplanetary space at the interfaces between slow and fast solar wind streams. This dissertation studies the three-dimensional orientation of planar magnetic structures within CIRs near Earth, how their orientation evolves, and the implications for the structure and properties of parent coronal holes. This dissertation also shows our work of modeling the response of the Heavy Ion Sensor (HIS) for the Solar Orbiter mission. We will discuss the methods and results of each chapter below. In Chapter 2, we have surveyed the properties of 153 co-rotating interaction regions (CIRs) observed at 1 AU from January, 1995 through December, 2008. We identified that 74 of the 153 CIRs contain planar magnetic structures (PMSs). For planar and non-planar CIRs, we compared distributions of the bulk plasma and magnetic field parameters. Our identification of CIRs and their features yields the following results: (1) The thermal, magnetic, and dynamic pressures within CIRs are strongly correlated. (2) There is no statistical difference between planar and non-planar CIRs in the distributions and correlations between bulk plasma and magnetic field parameters. (3) The mean observed CIR azimuthal tilt is within 1 sigma of the predicted Parker spiral at 1 AU, while the mean meridional tilt is about 20°. (4) The meridional tilt of CIRs changes from one solar rotation to the next, with no relationship between successive reoccurrences. (5) The meridional tilt of CIRs in the ecliptic is not ordered by the magnetic field polarity of the parent coronal hole. (6) Although solar wind deflection is a function of CIR shape and speed, the relationship is not in agreement with that predicted by Lee [2000]. We conclude the following: (1) PMSs in CIRs are not caused by a unique characteristic in the local plasma or magnetic field. (2) The lack of relationship between CIR tilt and its parent coronal hole suggests that coronal

  18. Influence of obstructive sleep apnea syndrome in the fluctuation of the submaximal isometric torque of knee extensors in patients with early-grade osteoarthritis

    PubMed Central

    Silva, Andressa; Mello, Marco T.; Serrão, Paula R.; Luz, Roberta P.; Bittencourt, Lia R.; Mattiello, Stela M.

    2015-01-01

    OBJECTIVE: The aim of this study was to investigate whether obstructive sleep apnea (OSA) alters the fluctuation of submaximal isometric torque of the knee extensors in patients with early-grade osteoarthritis (OA). METHOD: The study included 60 male volunteers, aged 40 to 70 years, divided into four groups: Group 1 (G1) - Control (n=15): without OA and without OSA; Group 2 (G2) (n=15): with OA and without OSA; Group 3 (G3) (n=15): without OA and with OSA; and Group 4 (G4) (n=15) with OA and with OSA. Five patients underwent maximal isometric contractions of 10 seconds duration each, with the knee at 60° of flexion to determine peak torque at 60°. To evaluate the fluctuation of torque, 5 submaximal isometric contractions (50% of maximum peak torque) of 10 seconds each, which were calculated from the standard deviation of torque and coefficient of variation, were performed. RESULTS: Significant differences were observed between groups for maximum peak torque, while G4 showed a lower value compared with G1 (p=0.005). Additionally, for the average torque exerted, G4 showed a lower value compared to the G1 (p=0.036). However, no differences were found between the groups for the standard deviation (p=0.844) and the coefficient of variation (p=0.143). CONCLUSION: The authors concluded that OSA did not change the parameters of the fluctuation of isometric submaximal torque of knee extensors in patients with early-grade OA. PMID:26443974

  19. Mechanics of torque generation in the bacterial flagellar motor.

    PubMed

    Mandadapu, Kranthi K; Nirody, Jasmine A; Berry, Richard M; Oster, George

    2015-08-11

    The bacterial flagellar motor (BFM) is responsible for driving bacterial locomotion and chemotaxis, fundamental processes in pathogenesis and biofilm formation. In the BFM, torque is generated at the interface between transmembrane proteins (stators) and a rotor. It is well established that the passage of ions down a transmembrane gradient through the stator complex provides the energy for torque generation. However, the physics involved in this energy conversion remain poorly understood. Here we propose a mechanically specific model for torque generation in the BFM. In particular, we identify roles for two fundamental forces involved in torque generation: electrostatic and steric. We propose that electrostatic forces serve to position the stator, whereas steric forces comprise the actual "power stroke." Specifically, we propose that ion-induced conformational changes about a proline "hinge" residue in a stator α-helix are directly responsible for generating the power stroke. Our model predictions fit well with recent experiments on a single-stator motor. The proposed model provides a mechanical explanation for several fundamental properties of the flagellar motor, including torque-speed and speed-ion motive force relationships, backstepping, variation in step sizes, and the effects of key mutations in the stator. PMID:26216959

  20. Acceleration and torque feedback for robotic control - Experimental results

    NASA Technical Reports Server (NTRS)

    Mclnroy, John E.; Saridis, George N.

    1990-01-01

    Gross motion control of robotic manipulators typically requires significant on-line computations to compensate for nonlinear dynamics due to gravity, Coriolis, centripetal, and friction nonlinearities. One controller proposed by Luo and Saridis avoids these computations by feeding back joint acceleration and torque. This study implements the controller on a Puma 600 robotic manipulator. Joint acceleration measurement is obtained by measuring linear accelerations of each joint, and deriving a computationally efficient transformation from the linear measurements to the angular accelerations. Torque feedback is obtained by using the previous torque sent to the joints. The implementation has stability problems on the Puma 600 due to the extremely high gains inherent in the feedback structure. Since these high gains excite frequency modes in the Puma 600, the algorithm is modified to decrease the gain inherent in the feedback structure. The resulting compensator is stable and insensitive to high frequency unmodeled dynamics. Moreover, a second compensator is proposed which uses acceleration and torque feedback, but still allows nonlinear terms to be fed forward. Thus, by feeding the increment in the easily calculated gravity terms forward, improved responses are obtained. Both proposed compensators are implemented, and the real time results are compared to those obtained with the computed torque algorithm.

  1. Results and Analysis from Space Suit Joint Torque Testing

    NASA Technical Reports Server (NTRS)

    Matty, Jennifer

    2010-01-01

    A space suit's mobility is critical to an astronaut's ability to perform work efficiently. As mobility increases, the astronaut can perform tasks for longer durations with less fatigue. Mobility can be broken down into two parts: range of motion (ROM) and torque. These two measurements describe how the suit moves and how much force it takes to move. Two methods were chosen to define mobility requirements for the Constellation Space Suit Element (CSSE). One method focuses on range of motion and the second method centers on joint torque. A joint torque test was conducted to determine a baseline for current advanced space suit joint torques. This test utilized the following space suits: Extravehicular Mobility Unit (EMU), Advanced Crew Escape Suit (ACES), I-Suit, D-Suit, Enhanced Mobility (EM)- ACES, and Mark III (MK-III). Data was collected data from 16 different joint movements of each suit. The results were then reviewed and CSSE joint torque requirement values were selected. The focus of this paper is to discuss trends observed during data analysis.

  2. Reconstruction of Twist Torque in Main Parachute Risers

    NASA Technical Reports Server (NTRS)

    Day, Joshua D.

    2015-01-01

    The reconstruction of twist torque in the Main Parachute Risers of the Capsule Parachute Assembly System (CPAS) has been successfully used to validate CPAS Model Memo conservative twist torque equations. Reconstruction of basic, one degree of freedom drop tests was used to create a functional process for the evaluation of more complex, rigid body simulation. The roll, pitch, and yaw of the body, the fly-out angles of the parachutes, and the relative location of the parachutes to the body are inputs to the torque simulation. The data collected by the Inertial Measurement Unit (IMU) was used to calculate the true torque. The simulation then used photogrammetric and IMU data as inputs into the Model Memo equations. The results were then compared to the true torque results to validate the Model Memo equations. The Model Memo parameters were based off of steel risers and the parameters will need to be re-evaluated for different materials. Photogrammetric data was found to be more accurate than the inertial data in accounting for the relative rotation between payload and cluster. The Model Memo equations were generally a good match and when not matching were generally conservative.

  3. Estimation of muscle torque in various combat sports.

    PubMed

    Pędzich, Wioletta; Mastalerz, Andrzej; Sadowski, Jerzy

    2012-01-01

    The purpose of the research was to compare muscle torque of elite combat groups. Twelve taekwondo WTF athletes, twelve taekwondo ITF athletes and nine boxers participated in the study. Measurements of muscle torques were done under static conditions on a special stand which belonged to the Department of Biomechanics. The sum of muscle torque of lower right and left extremities of relative values was significantly higher for taekwondo WTF athletes than for boxers (16%, p < 0.001 for right and 10%, p < 0.05 for left extremities) and taekwondo ITF (10%, p < 0.05 for right and 8% for left extremities). Taekwondo ITF athletes attained significantly higher absolute muscle torque values than boxers for elbow flexors (20%, p < 0.05 for right and 11% for left extremities) and extensors (14% for right and 18%, p < 0.05 for left extremities) and shoulder flexors (10% for right and 12%, p < 0.05 for left extremities) and extensors (11% for right and 1% for left extremities). Taekwondo WTF and taekwondo ITF athletes obtained significantly different relative values of muscle torque of the hip flexors (16%, p < 0.05) and extensors (11%, p < 0.05) of the right extremities. PMID:23394114

  4. Joint Torque Reduction of a Three Dimensional Redundant Planar Manipulator

    PubMed Central

    Yahya, Samer; Moghavvemi, Mahmoud; Almurib, Haider Abbas F.

    2012-01-01

    Research on joint torque reduction in robot manipulators has received considerable attention in recent years. Minimizing the computational complexity of torque optimization and the ability to calculate the magnitude of the joint torque accurately will result in a safe operation without overloading the joint actuators. This paper presents a mechanical design for a three dimensional planar redundant manipulator with the advantage of the reduction in the number of motors needed to control the joint angle, leading to a decrease in the weight of the manipulator. Many efforts have been focused on decreasing the weight of manipulators, such as using lightweight joints design or setting the actuators at the base of the manipulator and using tendons for the transmission of power to these joints. By using the design of this paper, only three motors are needed to control any n degrees of freedom in a three dimensional planar redundant manipulator instead of n motors. Therefore this design is very effective to decrease the weight of the manipulator as well as the number of motors needed to control the manipulator. In this paper, the torque of all the joints are calculated for the proposed manipulator (with three motors) and the conventional three dimensional planar manipulator (with one motor for each degree of freedom) to show the effectiveness of the proposed manipulator for decreasing the weight of the manipulator and minimizing driving joint torques. PMID:22969326

  5. Large Torque Variations in Two Soft Gamma Repeaters

    NASA Technical Reports Server (NTRS)

    Woods, Peter M.; Kouveliotou, Chryssa; Gogus, Ersin; Finger, Mark H.; Swank, Jean; Markwardt, Craig B.; Hurley, Kevin; vanderKlis, Michiel

    2002-01-01

    We have monitored the pulse frequencies of the two soft gamma repeaters SGR 1806-20 and SGR 1900+14 through the beginning of year 2001 using primarily Rossi X-Ray Timing Explorer Proportional Counter Array observations. In both sources, we observe large changes in the spin-down torque up to a factor of approximately 4, which persist for several months. Using long-baseline phase-connected timing solutions as well as the overall frequency histories, we construct torque noise power spectra for each SGR (Soft Gamma Repeater). The power spectrum of each source is very red (power-law slope is approximately -3.5). The torque noise power levels are consistent with some accreting systems on timescales of approximately 1 yr, yet the full power spectrum is much steeper in frequency than any known accreting source. To the best of our knowledge, torque noise power spectra with a comparably steep frequency dependence have been seen only in young, glitching radio pulsars (e.g., Vela). The observed changes in spin-down rate do not correlate with burst activity; therefore, the physical mechanisms behind each phenomenon are also likely unrelated. Within the context of the magnetar model, seismic activity can not account for both the bursts and the long-term torque changes unless the seismically active regions are decoupled from one another.

  6. CoRoT sounds the stars: p-mode parameters of Sun-like oscillations on HD 49933

    NASA Astrophysics Data System (ADS)

    Appourchaux, T.; Michel, E.; Auvergne, M.; Baglin, A.; Toutain, T.; Baudin, F.; Benomar, O.; Chaplin, W. J.; Deheuvels, S.; Samadi, R.; Verner, G. A.; Boumier, P.; García, R. A.; Mosser, B.; Hulot, J.-C.; Ballot, J.; Barban, C.; Elsworth, Y.; Jiménez-Reyes, S. J.; Kjeldsen, H.; Régulo, C.; Roxburgh, I. W.

    2008-09-01

    Context: The first asteroseismology results from CoRoT are presented, on a star showing Sun-like oscillations. We have analyzed a 60 day lightcurve of high-quality photometric data collected by CoRoT on the F5 V star HD 49933. The data reveal a rich spectrum of overtones of low-degree p modes. Aims: Our aim was to extract robust estimates of the key parameters of the p modes observed in the power spectrum of the lightcurve. Methods: Estimation of the mode parameters was performed using maximum likelihood estimation of the power spectrum. A global fitting strategy was adopted whereby 15 mode orders of the mode spectrum (45 modes) were fitted simultaneously. Results: The parameter estimates that we list include mode frequencies, peak linewidths, mode amplitudes, and a mean rotational frequency splitting. We find that the average large frequency (overtone) spacing derived from the fitted mode frequencies is 85.9 ± 0.15 μHz. The frequency of maximum amplitude of the radial modes is at 1760 μHz, where the observed rms mode amplitude is 3.75 ± 0.23 ppm. The mean rotational splitting of the non-radial modes appears to be in the range ≈2.7 μHz to ≈3.4 μHz. The angle of inclination offered by the star, as determined by fits to the amplitude ratios of the modes, appears to be in the range ≈50 degrees to ≈62 degrees. The CoRoT space mission, launched on 2006 December 27, was developed and is operated by the CNES, with participation of the Science Programs of ESA, ESA's RSSD, Austria, Belgium, Brazil, Germany and Spain.

  7. The CoRoT target HD 175726: an active star with weak solar-like oscillations

    NASA Astrophysics Data System (ADS)

    Mosser, B.; Michel, E.; Appourchaux, T.; Barban, C.; Baudin, F.; Boumier, P.; Bruntt, H.; Catala, C.; Deheuvels, S.; García, R. A.; Gaulme, P.; Regulo, C.; Roxburgh, I.; Samadi, R.; Verner, G.; Auvergne, M.; Baglin, A.; Ballot, J.; Benomar, O.; Mathur, S.

    2009-10-01

    Context: The CoRoT short runs give us the opportunity to observe a large variety of late-type stars through their solar-like oscillations. We report observations of the star HD 175726 that lasted for 27 days during the first short run of the mission. The time series reveals a high-activity signal and the power spectrum presents an excess due to solar-like oscillations with a low signal-to-noise ratio. Aims: Our aim is to identify the most efficient tools to extract as much information as possible from the power density spectrum. Methods: The most productive method appears to be the autocorrelation of the time series, calculated as the spectrum of the filtered spectrum. This method is efficient, very rapid computationally, and will be useful for the analysis of other targets, observed with CoRoT or with forthcoming missions such as Kepler and Plato. Results: The mean large separation has been measured to be 97.2±0.5 μHz, slightly below the expected value determined from solar scaling laws. We also show strong evidence for variation of the large separation with frequency. The bolometric mode amplitude is only 1.7±0.25 ppm for radial modes, which is 1.7 times less than expected. Due to the low signal-to-noise ratio, mode identification is not possible for the available data set of HD 175726. The CoRoT space mission, launched on 2006 December 27, was developed and is operated by the CNES, with participation of the Science Programs of ESA, ESAs RSSD, Austria, Belgium, Brazil, Germany and Spain.

  8. Could CoRoT-7b and Kepler-10b be remnants of evaporated gas or ice giants?

    PubMed

    Leitzinger, M; Odert, P; Kulikov, Yu N; Lammer, H; Wuchterl, G; Penz, T; Guarcello, M G; Micela, G; Khodachenko, M L; Weingrill, J; Hanslmeier, A; Biernat, H K; Schneider, J

    2011-10-01

    We present thermal mass loss calculations over evolutionary time scales for the investigation if the smallest transiting rocky exoplanets CoRoT-7b (∼1.68REarth) and Kepler-10b (∼1.416REarth) could be remnants of an initially more massive hydrogen-rich gas giant or a hot Neptune-class exoplanet. We apply a thermal mass loss formula which yields results that are comparable to hydrodynamic loss models. Our approach considers the effect of the Roche lobe, realistic heating efficiencies and a radius scaling law derived from observations of hot Jupiters. We study the influence of the mean planetary density on the thermal mass loss by placing hypothetical exoplanets with the characteristics of Jupiter, Saturn, Neptune, and Uranus to the orbital location of CoRoT-7b at 0.017 AU and Kepler-10b at 0.01684 AU and assuming that these planets orbit a K- or G-type host star. Our findings indicate that hydrogen-rich gas giants within the mass domain of Saturn or Jupiter cannot thermally lose such an amount of mass that CoRoT-7b and Kepler-10b would result in a rocky residue. Moreover, our calculations show that the present time mass of both rocky exoplanets can be neither a result of evaporation of a hydrogen envelope of a "Hot Neptune" nor a "Hot Uranus"-class object. Depending on the initial density and mass, these planets most likely were always rocky planets which could lose a thin hydrogen envelope, but not cores of thermally evaporated initially much more massive and larger objects. PMID:21969736

  9. Could CoRoT-7b and Kepler-10b be remnants of evaporated gas or ice giants?

    PubMed Central

    Leitzinger, M.; Odert, P.; Kulikov, Yu.N.; Lammer, H.; Wuchterl, G.; Penz, T.; Guarcello, M.G.; Micela, G.; Khodachenko, M.L.; Weingrill, J.; Hanslmeier, A.; Biernat, H.K.; Schneider, J.

    2011-01-01

    We present thermal mass loss calculations over evolutionary time scales for the investigation if the smallest transiting rocky exoplanets CoRoT-7b (∼1.68REarth) and Kepler-10b (∼1.416REarth) could be remnants of an initially more massive hydrogen-rich gas giant or a hot Neptune-class exoplanet. We apply a thermal mass loss formula which yields results that are comparable to hydrodynamic loss models. Our approach considers the effect of the Roche lobe, realistic heating efficiencies and a radius scaling law derived from observations of hot Jupiters. We study the influence of the mean planetary density on the thermal mass loss by placing hypothetical exoplanets with the characteristics of Jupiter, Saturn, Neptune, and Uranus to the orbital location of CoRoT-7b at 0.017 AU and Kepler-10b at 0.01684 AU and assuming that these planets orbit a K- or G-type host star. Our findings indicate that hydrogen-rich gas giants within the mass domain of Saturn or Jupiter cannot thermally lose such an amount of mass that CoRoT-7b and Kepler-10b would result in a rocky residue. Moreover, our calculations show that the present time mass of both rocky exoplanets can be neither a result of evaporation of a hydrogen envelope of a “Hot Neptune” nor a “Hot Uranus”-class object. Depending on the initial density and mass, these planets most likely were always rocky planets which could lose a thin hydrogen envelope, but not cores of thermally evaporated initially much more massive and larger objects. PMID:21969736

  10. Could CoRoT-7b and Kepler-10b be remnants of evaporated gas or ice giants?

    PubMed

    Leitzinger, M; Odert, P; Kulikov, Yu N; Lammer, H; Wuchterl, G; Penz, T; Guarcello, M G; Micela, G; Khodachenko, M L; Weingrill, J; Hanslmeier, A; Biernat, H K; Schneider, J

    2011-10-01

    We present thermal mass loss calculations over evolutionary time scales for the investigation if the smallest transiting rocky exoplanets CoRoT-7b (∼1.68REarth) and Kepler-10b (∼1.416REarth) could be remnants of an initially more massive hydrogen-rich gas giant or a hot Neptune-class exoplanet. We apply a thermal mass loss formula which yields results that are comparable to hydrodynamic loss models. Our approach considers the effect of the Roche lobe, realistic heating efficiencies and a radius scaling law derived from observations of hot Jupiters. We study the influence of the mean planetary density on the thermal mass loss by placing hypothetical exoplanets with the characteristics of Jupiter, Saturn, Neptune, and Uranus to the orbital location of CoRoT-7b at 0.017 AU and Kepler-10b at 0.01684 AU and assuming that these planets orbit a K- or G-type host star. Our findings indicate that hydrogen-rich gas giants within the mass domain of Saturn or Jupiter cannot thermally lose such an amount of mass that CoRoT-7b and Kepler-10b would result in a rocky residue. Moreover, our calculations show that the present time mass of both rocky exoplanets can be neither a result of evaporation of a hydrogen envelope of a "Hot Neptune" nor a "Hot Uranus"-class object. Depending on the initial density and mass, these planets most likely were always rocky planets which could lose a thin hydrogen envelope, but not cores of thermally evaporated initially much more massive and larger objects.

  11. Seventy new non-eclipsing BEER binaries discovered in CoRoT lightcurves and confirmed by RVs from AAOmega

    NASA Astrophysics Data System (ADS)

    Tal-Or, Lev; Faigler, Simchon; Mazeh, Tsevi

    2015-09-01

    We applied the BEER algorithm to the CoRoT lightcurves from the first five LRc fields and identified 481 non-eclipsing BEER candidates with periodic lightcurve modulations and amplitudes of 0.5 - 87 mmag. Medium-resolution spectra of 281 candidates were obtained in a seven-night AAOmega radial-velocity (RV) campaign, with a precision of ˜ 1 km/s. The RVs confirmed the binarity of 70 of the BEER candidates, with periods of 0.3 - 10 days.

  12. VizieR Online Data Catalog: Planetary transit candidates in CoRoT SRc01 field (Erikson+, 2012)

    NASA Astrophysics Data System (ADS)

    Erikson, A.; Santerne, A.; Renner, S.; Barge, P.; Aigrain, S.; Alapini, A.; Almenara, J.-M.; Alonso, R.; Auvergne, M.; Baglin, A.; Benz, W.; Bonomo, A. S.; Borde, P.; Bouchy, F.; Bruntt, H.; Cabrera, J.; Carone, L.; Carpano, S.; Csizmadia, Sz.; Deleuil, M.; Deeg, H. J.; Diaz, R. F.; Dvorak, R.; Ferraz-Mello, S.; Fridlund, M.; Gandolfi, D.; Gazzano, J.-C.; Gillon, M.; Guenther, E. W.; Guillot, T.; Hatzes, A.; Hebrard, G.; Jorda, L.; Lammer, H.; Leger, A.; Llebaria, A.; Mayor, M.; Mazeh, T.; Moutou, C.; Ollivier, M.; Ofir, A.; Paetzold, M.; Pepe, F.; Pont, F.; Queloz, D.; Rabus, M.; Rauer, H.; Regulo, C.; Rouan, D.; Samuel, B.; Schneider, J.; Shporer, A.; Tingley, B.; Udry, S.; Wuchterl, G.

    2012-04-01

    Among the acquired data, we analyzed those for 1269 sources in the chromatic bands and 5705 in the monochromatic band. Instrumental noise and the stellar variability were treated with several detrending tools, to which several transit-search algorithms were subsequently applied. Fifty-one sources were classified as planetary transit candidates and 26 were followed up with ground-based observations. Until now, no planet has been detected in the CoRoT data from the SRc01 field. (1 data file).

  13. Displaced narrow absorption components in the spectra of mass-losing OB stars - Indications of corotating interaction regions?

    NASA Technical Reports Server (NTRS)

    Mullan, D. J.

    1986-01-01

    The discovery of displaced narrow components (DNCs) in an increasingly large number of stars of various spectral types suggests that an explanation of these features may contribute significantly to understanding of winds from stars of all types. The reported properties of DNCs are summarized here with a view to evaluating one particular scenario for DNC formation which involves corotating interaction regions (CIRs) in the stellar wind. The relevant features of the CIR scenario are summarized, and the extent to which DNC properties support the CIR scenario is discussed.

  14. Observed distribution functions of H, He, C, O, and Fe in corotating energetic particle streams: Implications for interplanetary acceleration and propagation

    NASA Technical Reports Server (NTRS)

    Gloeckler, G.; Hovestadt, D.; Fisk, L. A.

    1979-01-01

    Distribution functions for H, He, C, O, and Fe derived from our IMP 8 measurements of approximately 0.15 to approximately 8 MeV/nucleon particles in three corotating streams observed near earth are shown to have a simple exponential dependence on the particle speed. The e-folding speed, v sub o, is typically 0.01c, is found to be the same for the distribution functions of all elements examined, and varies little from one corotating event to the next. The relative abundances of energetic particles in these events resemble most closely the solar coronal composition and, thus, presumably that of the solar wind. These results may imply that the acceleration of these particles, which occurs in corotating interaction regions at several AU from the sun, is by a statistical process.

  15. Rotation of a liquid crystal by the Casimir torque

    NASA Astrophysics Data System (ADS)

    Somers, David A. T.; Munday, Jeremy N.

    2015-03-01

    We present a calculation of the Casimir torque acting on a liquid crystal near a birefringent crystal. In this system, a liquid crystal bulk is uniformly aligned at one surface and is twisted at the other surface by a birefringent crystal, e.g., barium titanate. The liquid crystal is separated from the solid crystal by an isotropic, transparent material such as SiO2. By varying the thickness of the deposited layer, we can observe the effect of retardation on the torque (which differentiates it from the close-range van der Waals torque). We find that a barium titanate slab would cause 5CB (4 -cyano -4 '-pentylbiphenyl) liquid crystal to rotate by 10∘ through its bulk when separated by 35 nm of SiO2. The optical technique for measuring this twist is also outlined.

  16. Magnetic torque anomaly in the quantum limit of Weyl semimetals

    NASA Astrophysics Data System (ADS)

    Moll, Philip J. W.; Potter, Andrew C.; Nair, Nityan L.; Ramshaw, B. J.; Modic, K. A.; Riggs, Scott; Zeng, Bin; Ghimire, Nirmal J.; Bauer, Eric D.; Kealhofer, Robert; Ronning, Filip; Analytis, James G.

    2016-08-01

    Electrons in materials with linear dispersion behave as massless Weyl- or Dirac-quasiparticles, and continue to intrigue due to their close resemblance to elusive ultra-relativistic particles as well as their potential for future electronics. Yet the experimental signatures of Weyl-fermions are often subtle and indirect, in particular if they coexist with conventional, massive quasiparticles. Here we show a pronounced anomaly in the magnetic torque of the Weyl semimetal NbAs upon entering the quantum limit state in high magnetic fields. The torque changes sign in the quantum limit, signalling a reversal of the magnetic anisotropy that can be directly attributed to the topological nature of the Weyl electrons. Our results establish that anomalous quantum limit torque measurements provide a direct experimental method to identify and distinguish Weyl and Dirac systems.

  17. Magnetic torque anomaly in the quantum limit of Weyl semimetals.

    PubMed

    Moll, Philip J W; Potter, Andrew C; Nair, Nityan L; Ramshaw, B J; Modic, K A; Riggs, Scott; Zeng, Bin; Ghimire, Nirmal J; Bauer, Eric D; Kealhofer, Robert; Ronning, Filip; Analytis, James G

    2016-01-01

    Electrons in materials with linear dispersion behave as massless Weyl- or Dirac-quasiparticles, and continue to intrigue due to their close resemblance to elusive ultra-relativistic particles as well as their potential for future electronics. Yet the experimental signatures of Weyl-fermions are often subtle and indirect, in particular if they coexist with conventional, massive quasiparticles. Here we show a pronounced anomaly in the magnetic torque of the Weyl semimetal NbAs upon entering the quantum limit state in high magnetic fields. The torque changes sign in the quantum limit, signalling a reversal of the magnetic anisotropy that can be directly attributed to the topological nature of the Weyl electrons. Our results establish that anomalous quantum limit torque measurements provide a direct experimental method to identify and distinguish Weyl and Dirac systems. PMID:27545105

  18. Mechanics of Re-Torquing in Bolted Flange Connections

    NASA Technical Reports Server (NTRS)

    Gordon, Ali P.; Drilling Brian; Weichman, Kyle; Kammerer, Catherine; Baldwin, Frank

    2010-01-01

    It has been widely accepted that the phenomenon of time-dependent loosening of flange connections is a strong consequence of the viscous nature of the compression seal material. Characterizing the coupled interaction between gasket creep and elastic bolt stiffness has been useful in predicting conditions that facilitate leakage. Prior advances on this sub-class of bolted joints has lead to the development of (1) constitutive models for elastomerics, (2) initial tightening strategies, (3) etc. The effect of re-torque, which is a major consideration for typical bolted flange seals used on the Space Shuttle fleet, has not been fully characterized, however. The current study presents a systematic approach to characterizing bolted joint behavior as the consequence of sequentially applied torques. Based on exprimenta1 and numerical results, the optimal re-torquing parameters have been identified that allow for the negligible load loss after pre-load application

  19. Advanced torque converters for robotics and space applications

    NASA Technical Reports Server (NTRS)

    1985-01-01

    This report describes the results of the evaluation of a novel torque converter concept. Features of the concept include: (1) automatic and rapid adjustment of effective gear ratio in response to changes in external torque (2) maintenance of output torque at zero output velocity without loading the input power source and (3) isolation of input power source from load. Two working models of the concept were fabricated and tested, and a theoretical analysis was performed to determine the limits of performance. It was found that the devices are apparently suited to certain types of tool driver applications, such as screwdrivers, nut drivers and valve actuators. However, quantiative information was insufficient to draw final conclusion as to robotic applications.

  20. Torque vectoring for improving stability of small electric vehicles

    NASA Astrophysics Data System (ADS)

    Grzegożek, W.; Weigel-Milleret, K.

    2016-09-01

    The electric vehicles solutions based on the individually controlled electric motors propel a single wheel allow to improve the dynamic properties of the vehicle by varying the distribution of the driving torque. Most of the literature refer to the vehicles with a track typical for passenger cars. This paper examines whether the narrow vehicle (with a very small track) torque vectoring bring a noticeable change of the understeer characteristics and whether torque vectoring is possible to use in securing a narrow vehicle from roll over (roll mitigation). The paper contains road tests of the steering characteristics (steady state understeer characteristic quasi-static acceleration with a fixed steering wheel (SH = const) and on the constant radius track (R = const)) of the narrow vehicle. The vehicle understeer characteristic as a function of a power distribution is presented.