BACKGROUND Gradual increases in mass such as during pregnancy are associated with changes in gait at natural velocities. The purpose of this study was to examine how added mass at natural and imposed slow walking velocities would affect gait parameters. METHODS Eighteen adult females walked at two velocities (natural and 25 % slower than their natural pace) under four mass conditions (initial...

M. S. Howe J. Fluid Mech. 206, 131 1989 presented integral formulas for the force and torque on a rigid body that permit the identification of the separate influences of added mass, normal stresses induced by free vorticity, and viscous skin friction. Here a simple extension of Howe’s formulas is done for systems of several rigid bodies. The goal is to separate these effects on each rigid body....

The towing of an underwater object by means of a cable attached to a ship is an important problem in underwater technology. An underwater towed body is generally at the mercy of hydrodynamic and hydrostatic forces, which controls its motion through water. These forces affect the depth characteristics of the towed body giving specific configuration to the towline. This work consists of the devel...

The motion and the action of microbubbles in homogeneous and isotropic turbulence are investigated through ~three-dimensional! direct numerical simulations of the Navier–Stokes equations and applying the Lagrangian approach to track the bubble trajectories. The forces acting on the bubbles are added mass, drag, lift, and gravity. The bubbles are found to accumulate in vortices, preferably on th...

In this study, a set of experimental results for wave forces acting on a cylinder oscillating with dual frequency in still water are reported. The experiment was designed to mimic a cylinder slowly oscillating in regular waves, with the high-frequency oscillation representing the wave motion and the low-frequency oscillation, the slow drift motion. The inline forces acting on the cylinder were ...

In this paper, we present an immersed boundary method for simulating moving contact lines with surfactant. The governing equations are the incompressible Navier-Stokes equations with the usual mixture of Eulerian fluid variables and Lagrangian interfacial markers. The immersed boundary force has two components: one from the nonhomogeneous surface tension determined by the distribution of surfac...

A robust teleoperation controller design method for an underwater manipulator is proposed considering the master and the underwater slave separately. To achieve transparency and stability for a teleoperation of an underwater manipulator in unknown environments with time-varying uncertainties such as added mass, buoyancy, hydraulic drag and friction effect, an adaptive sliding mode control schem...

PURPOSE To analyze the influence of weight, height and body mass index in the axial tongue force. METHODS Medical records with data from 44 subjects aged between 20 and 37 years, 11 (25%) males and 33 (75%) female, were analyzed. The investigated information were weight, height, result of clinical evaluation for tongue force (lingual tonus) and instrumental assessment of axial tongue force, w...

A wave breaking against a sea wall causes high pressure gradients to act along the sea bed, pushing objects away from the wall. This situation is modelled using pressure impulse theory to show that, for a large object near a sea wall, the impulsive force due to the wave will move the object. This force can be found, given knowledge of the added mass and volume of an object. In particular, if th...

We determine conservative and dissipative tip-sample interaction forces from the amplitude and phase response of acoustically driven atomic force microscope (AFM) cantilevers using a non-polar model fluid (octamethylcyclotetrasiloxane, which displays strong molecular layering) and atomically flat surfaces of highly ordered pyrolytic graphite. Taking into account the base motion and the frequenc...