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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] Disturbance torques in Low Earth Orbits may present a harsh environment for the successful operation of small satellite missions. The effects of gravity-gradient and aerodynamic torques are studied individually at various altitudes for low Earth orbit. Results show that for a basic 2U CubeSat, the gravity-gradient torque is highly perturbing, whereas the effect of aerodynamic torque is established to be so dominant that it offers attitude stabilization in lower altitudes; and may be used as a means of passive attitude stabilization. (paper)
[en] The gustiness is a common motion form of debris flow, especially viscous debris flow. However, few researches have considered the gustiness into the impact characteristics of debris flow, which needs further research. In this study, the check dam was used as the load receptor to study the impact characteristics of gustiness debris flow. The results show that, under the same general flow depth, the dam stress considering the impact of gustiness debris flow is far less than that of disposable continuous debris flow. The impact force increases with the increase of the times of gustiness debris flow, and the impact torque increases linearly. Under the impact of gustiness debris flow, the displacement and stress of the dam vary in the same rule. The safety factors of anti-sliding and anti-overturning of the dam under the effect of gustiness debris flow are larger than those of disposable continuous debris flow, and the decrease rate of the safety factors increases with the increase of the times of gustiness debris flow. And under the condition of the same total flow depth, the increase of the debris flow depth can significantly decrease the stability of dam. The conclusions can provide reference for the design of blocking structures of gustiness and frequent debris flow. (paper)
[en] To transfer torque while reducing vibration and shock, a rotary magnetorheological flexible joint (MRFJ) with tunable stiffness and damping characteristics is proposed in this study. Equivalent variable stiffness and damping principle for the MRFJ is derived analytically. The structure and parameters of the MRFJ are designed. The variable stiffness and damping characteristics of a prototype of MRFJ is measured. The test results show that the variable stiffness and damping characteristics of the MRF can be tuned independently with variable input current. The theoretic results agree well with the experimental results. (paper)
[en] It is considered the problem of motion of two viscoelastic bodies in the gravitational field of MMP. Earlier we found the displacements of points of bodies caused by the action of centrifugal, elastic and dissipative forces. In this paper we calculated analytically three PP using these displacements for centrifugal, elastic and dissipative forces. These three types of displacements change accordingly the shape of the body. And PP is due to the difference between the shape of deformable bodies and balls. Knowing the PP we can find the torques, which determine the rotational motion of the body. As an example, we have calculated the shape of the body caused by elastic displacements and the torques acting on the body. (paper)
[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] An analysis of a conventional gear wheel shot with MPK methodology has been processed by many authors before. Harmonic gearbox systems are composed of rigid and flexible parts through which the torque is transmitted, thus generating power. The contact pressure is specifically distributed through more teeth whilst against conventional gearbox systems. Firstly, a design description of a dynamic calculation model of a harmonic gearbox system in the planar strain is analysed in this article, as well as the definition of each contact constraint between the rigid and flexible parts of these gear systems in respect of “GLUE” and “TOUCHING” contact types. The last part of this article deals with the force distribution analysis in the teeth with respect to the frictional forces in them. The graphical conclusions of this pressure on each tooth were made. This article mainly focuses on the analysis of the stress in a gear tooth of the harmonic gearbox systems, as well as the research of a special trajectory of the rigid and flexible entity in a solid circular spline of such gear systems. (paper)
[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] The processes of currents switching in stator windings have been explained by the existence of the electromagnetic torque ripples in the electric drive with the field-regulated reluctance machine. The maximum value of ripples in the open loop control system for the six-phase machine can reach 20 percent from the developed electromagnetic torque. This method allows one to make calculation of ripple spike towards average torque developed by the electromotor for the different number of phases. Application of a trapezoidal form of current at six phases became the solution. In case of a less number of phases than six, a ripple spike considerably increases, which is inadmissible. On the other hand, increasing the number of phases tends to the increase of the semiconductor inverter external dimensions based on the inconspicuous decreasing of a ripple spike. The creation and usage of high-speed control loops of current (HCLC) have been recommended for a reduction of the electromagnetic torque’s ripple level, as well as the appliance of positive current feedback in switching phase currents. This decision allowed one to receive a mean value of the torque more than 10%, compared to system without change, to reduce greatly ripple spike of the electromagnetic torque. The possibility of the electric drive effective operation with FRRM in emergency operation has been shown. (paper)