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[en] Radio timing observations of the high-magnetic-field pulsar PSR J1718-3718 have shown that it suffered a large glitch with Δνg/ν = (33.25 ± 0.01) x 10-6 between 2007 September (MJD 54336) and 2009 January (MJD 54855). This is the largest pulsar glitch ever observed. As is common, there was a small increase in braking torque at the time of the glitch but, unlike all other pulsars, the braking torque has continued to increase over the two years since the glitch. Polarization observations show that the mean pulse profile has about 30% linear polarization with a smooth change of position angle through the pulse, and give a rotation measure of -160 ± 22 rad m-2. There was no detectable change in pulse profile at the time of the glitch. The timing observations also gave an improved dispersion measure of 371.1 ± 1.7 cm-3 pc.
[en] 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
[en] It is shown that frequency chirping during fishbone activity can be attributed to the reactive torque exerted on the plasma during the instability burst, which slows down plasma rotation inside the q = 1 surface and reduces the mode frequency in the lab frame. Estimates show that the peak value of this torque can exceed the neutral beam torque in modern tokamaks. The simple line-broadened quasilinear burst model (Berk et al 1995 Nucl. Fusion 35 1661), properly adapted for the fishbone case, is capable of reproducing the key features of the bursting mode. (letter)
[en] We give sufficient conditions for the rigid body in the presence of an axisymmetric force field and a gyroscopic torque to admit a Hamilton-Poisson formulation. Even if by adding a gyroscopic torque we initially lose one of the conserved Casimirs, we recover another conservation law as a Casimir function for a modified Poisson structure. We apply this frame to several well-known results in the literature. -- Highlights: → Gyroscopic torques and sufficient conditions for a Hamilton-Poisson formulation. → An algorithm to find a third constant of motion as a Casimir function. → A unitary framework that encompasses well-known gyroscopic torques from literature.
[en] The power pulsations of Francis turbines are discussed which occur regularly at part load but sometimes even at full load. The main tool of the analysis is the torque equation of Francis runners which has been derived from basic mechanics neglecting only very small effects. The various potential pulsation sources are grouped according to their places of origin, namely those occurring (i) in the inlet flow path (rotor-stator interaction) (ii) at the runner (interblade vortices, rotating stall) and (iii) in the draft tube (spiraling vortex flow). Their effects are discussed assuming certain ideal symmetrical velocity distributions. The main theoretical conclusions are: (1) The shaft torque pulsations may be determined from the turbulent velocity field. (2) In case of steady quasi-axisymmetric inflow the main pulsation source does not belong to group (i). (3) Of the pulsation sources (ii) and (iii) one is self-excited while the other is forced. (4) If the discharge is constant and the draft tube vortex rotates uniformly, then (iii) cannot affect the shaft torque. (5) If (iii) is the main source of the torque pulsations then discharge fluctuation must appear. (6) If the discharge pulsation is too small then either (ii) is the main source, or essential interactions of (ii) and (iii) may be expected. Thus, the torque equation is seen as a powerful tool of the analysis, and for future research attention is focused to the discharge pulsation.
[en] Spin-orbit torque allows efficient control of the magnetization by using the in-plane current. Recent experiments found a strong angular dependence of spin-orbit torque. We theoretically investigate magnetization switching and domain wall motion induced by an angle-dependent spinorbit torque in perpendicularly magnetized layers. We obtain analytic expressions for the switching current and the domain wall velocity, which are in agreement with numerical results. Based on the expressions, we find that a spin-orbit torque that increases with increasing polar angle of the magnetization is beneficial for both switching and domain wall motion. Our result will serve as a guideline to design and interpret switching and domain wall experiments based on the spin-orbit torque.
[en] High strength bolt is used for the purpose of slip critical connection of steel structure. Nowadays torque shear type high strength bolt substitutes for high strength hexagon bolt at design of slip resistant joints. The torque shear type high strength bolt reaches the required torque when the pin tail twisted off at the end of shank. However it does not mean that this bolt has the required direct tension, but it subjects to torqued tension. This is why torque coefficient is affected on the design strength in tension on the process of tightening. The clamping method of torque shear bolts also follows the torque control method the same as the high strength hexagon bolt does. The torque coefficient of high strength bolt responds sensitively to the change of temperature still. In this study, torque test of torque shear bolts were conducted under the condition of -10 .deg. C, 0 .deg. C, 10 .deg. C, 20 .deg. C, 30 .deg. C, 40 .deg. C, 50 .deg. C to observe the trends of tension due to temperature fluctuation
[en] The security and integrity of the humble threaded fastener is not always the foremost consideration in the daily routine of engineers. The use of nuts and bolts is still one of the most widely applied methods of joining components together, yet throughout industry these items receive a smaller share of development costs pro rata than most other engineering components. (author)
[en] We compute the effect on a tokamak of applying a nonaxisymmetric magnetic perturbation (delta)B. An equilibrium with scalar pressure p yields zero net radial current, and therefore zero torque. Thus, the usual approach, which assumes scalar pressure, is not self-consistent, and masks the close connection which exists between that radial current and the in-surface currents, which provide shielding or amplification of (delta)B. Here, we analytically compute the pressure anisotropy, anisotropy, p#parallel#, p#perpendicular# and ≠ p, and from this, both the radial and in-surface currents. The surface-average of the radial current recovers earlier expressions for ripple transport, while the in-surface currents provide an expression for the amount of self-consistent shielding the plasma provides.