Particles moving on crystalline surfaces and driven by external forces or flow fields can acquire velocities along directions that deviate from that of the external force. This effect depends upon the characteristics of the particles, most notably particle size or particle index of refraction, and can therefore be (and has been) used to sort different particles. We introduce a simple model for ...

Computations of the drag force on a heavy quark moving through a thermal state of strongly coupled N = 4 super-Yang-Mills theory have appeared recently [1, 2, 3]. I compare the strength of this effect between N = 4 gauge theory and QCD, using the static force between external quarks to normalize the ’t Hooft coupling. Comparing N = 4 and QCD at fixed energy density then leads to a relaxation ti...

A method is proposed for evaluating the dynamical friction of linear bearings, whose motion is not perfectly linear due to some play in its internal mechanism. In this method, the moving part of a linear bearing is made to move freely, and the force acting on the moving part is measured as the inertial force given by the product of its mass and the acceleration of its centre of gravity. To eval...

We present results from molecular dynamics simulations of a sphere moving down an inclined plane made rough by glueing other spheres to it. The moving sphere experiences an eeective friction force due to collisions with the balls on the plane, and can maintain a steady state with a constant mean velocity for a certain range of inclination angles of the plane. Although the friction force is due ...

Inclusions, or defects, moving at constant velocity through free classical fields are shown to be subject to a drag force which depends on the field dynamics and the coupling of the inclusion to the field. The results are used to predict the drag exerted on inclusions, such as proteins, in lipid membranes due to their interaction with height and composition fluctuations. The force, measured in ...

Suppose we wanted to implement a particle simulator with a “floor”: a solid horizontal plane which particles could bounce off of, or lie on. Assuming all the particles started out above the floor, they’d all have to stay there for the rest of the simulation. How could we go about implementing this? Clearly, there are two problems. We need to detect when particles are near the floor, and when th...

An electrostatic actuator is designed to move a 1 mm mirror, 58 μm out of plane at 25 volts. Large out-of-plane displacement is obtained from repulsive forces generated on four sets of comb drive fingers attached to the mirror plate in the middle. The proposed actuator is a customized design of a previous study for low voltage applications. The static modeling of the actuator was performed usin...

We provide a theoretical model that describes the dielectric coupling of a two-dimensional (2D) layer of graphene, represented by a polarization function in the random phase approximation, and a semi-infinite three-dimensional (3D) substrate, represented by a surface response function in a non-local formulation. We concentrate on the role of the dynamic response of the substrate for low-frequen...

In this paper we shall investigate the normal surface displacement of the isotropic elastic half-space z > 0, due to a normal point force, F, which moves with constant speed, V, in the xdirection over the surface z = 0. This problem defines the Green's function for a class of elastodynamic contact problems for the half-space in which a frictionless rigid indenter moves at constant speed over th...

In this paper we consider a quark moving in D = 5, N = 2 supergravity thermal plasma. By using three charge non-extremal black hole solution (STU solution) we calculate drag force on the quark and diffusion constant from AdS/CFT correspondence.