The controlled rotation of solid particles trapped in a liquid by an ultrasonic vortex beam is observed. Single polystyrene beads, or clusters, can be trapped against gravity while simultaneously rotated. The induced rotation of a single particle is compared to a torque balance model accounting for the acoustic response of the particle. The measured torque (∼ 10 pNm for a driving acoustic power...

In a natural environment, insects are constantly being knocked about by wind or visual and mechanical perturbations. And yet they appear to be unperturbed and are able to correct their course with ease. The halteres, mentioned earlier, provide a fast gyroscopic sensor that enables a fruit fly to keep track of its angular rotational rate. Recent work has found that when a fruit fly’s body orient...

Analytical models are developed for the translation and rotation of metallic rods in a uniform electric field. The limits of thin and thick electric double layers are considered. These models include the effect of stripes of different metals along the length of the particle. Modeling results are compared to experimental measurements for metallic rods. Experiments demonstrate the increased align...

The free vibration characteristics of a dual split torque transmission are studied in this work. A transversetorsional coupling dynamic model is developed using lumped parameter method. The natural frequencies and mode shapes are calculated by solving the eigenvalue problem of the differential equations of motion. The vibration modes of the system are classified into translational mode and rota...

Three-dimensional numerical simulations are carried out by commercial software STAR-CCM+ to investigate the hydraulic transient and flow behaviours of a prototype pump-turbine during the normal shutdown process. The global characteristics and pressure fluctuations are analysed as the pump-turbine runs through the turbine mode, into the turbine braking mode, and finally into the reversed pump mo...

Variation in the angle α between a pulsar’s rotational and magnetic axes would change the torque and spin-down rate. We show that sudden increases in α, coincident with glitches, could be responsible for the persistent increases in spin-down rate that follow glitches in the Crab pulsar. Moreover, changes in α at a rate similar to that inferred for the Crab pulsar account naturally for the very ...

FliG, FliM, and FliN, key proteins for torque generation, are located in two rings. The first protein is in the M ring and the last two are in the C ring. The rotational symmetries of the C and M rings have been determined to be about 34 (this paper) and 26 (previous work), respectively. The mechanism proposed here depends on the symmetry mismatch between the rings: the C ring extends 34 levers...

The kinematics of a two rotational degrees-of-freedom (DOF) spherical parallel manipulator (SPM) is developed based on the coordinate transformation approach and the cosine rule of a trihedral angle. The angular displacement, angular velocity, and angular acceleration between the actuators and end-effector are thus determined. Moreover, the dynamic model of the 2-DOF SPM is established by using...

Rectified transport of active ellipsoidal particles is numerically investigated in a two-dimensional asymmetric potential. The out-of-equilibrium condition for the active particle is an intrinsic property, which can break thermodynamical equilibrium and induce the directed transport. It is found that the perfect sphere particle can facilitate the rectification, while the needlelike particle des...

In this paper we present a cable mechanism that realizes a nonlinear rotational spring from a linear translational spring. The spring is pulled by a cable wound around a non-circular spool, which is rigidly attached to the joint. The non-circular shape of the spool induces a nonlinear relationship between its angular position and the torque created by the tension of the cable. Depending on the ...