This paper is concerned with a class of time-optimal control problems for the swing and the ski. We first consider the motion of a man standing on a swing. For simplicity, we neglect friction and air resistance and assume that the mass of the swinger is concentrated in his baricenter B. Let θ be the angle formed by the swing and the downward vertical direction and r the radius of oscillation, i...

To win elections, candidates attempt to mobilize supporters and persuade swing voters. With what magnitude each operates across American elections is not clear. I argue that the influence of swing voters should depend upon change in the candidates across elections and that the consequences of changes in composition should depend upon the relative balance of campaign expenditures. I estimate a B...

ing from what seem to be the transitory phenomena, like the post-Communist and East Asian crises, we seem to be in the presence of an interesting situation where world inequality is driven by what happens to the relative incomes of the three large areas: (1) the rich countries of the West, (2) urban incomes in China and India, and (3) rural incomes in these two countries. The ratio between (2) ...

Children with cerebral palsy often walk with diminished knee extension during the terminal-swing phase, resulting in a troublesome "crouched" posture at initial contact and a shortened stride. Treatment of this gait abnormality is challenging because the factors that extend the knee during normal walking are not well understood, and because the potential of individual muscles to limit terminal-...

Healthy walking is characterized by pronounced arm swing and axial rotation. Aging effects on gait speed, stride length and stride time variability have been previously reported, however, less is known about aging effects on arm swing and axial rotation and their relationship to age-associated gait changes during usual walking and during more challenging conditions like dual tasking. Sixty heal...

This study investigated changes in lower-extremity joint work and power during the swing phase in a maximal accelerated sprinting. Twelve male sprinters performed 60 m maximal sprints while motion data was recorded. Lower-extremity joint work and power during the swing phase of each stride for both legs were calculated. Positive hip and negative knee work (≈4.3 and ≈-2.9 J kg-1) and mean power ...

Stiff-knee gait is characterized by diminished and delayed knee flexion during swing. Rectus femoris transfer surgery, a common treatment for stiff-knee gait, is often recommended when a patient exhibits prolonged activity of the rectus femoris muscle during swing. Treatment outcomes are inconsistent, in part, due to limited understanding of the biomechanical factors contributing to stiff-knee ...

At the time of power swing the measured impedance lies inside the relay operating region. There is undesired tripping of Distance relay during power swing without having any fault. So relay must be blocked & must trip after a fault occur during power swing. This paper presents new technique to detect fault during power swing. In the proposed technique process starts by simulating the double tra...

— The design of an efficient monolithic buck converter is presented in this paper. A low swing MOSFET gate drive technique is proposed that improves the efficiency characteristics of a DC-DC converter. A model of the parasitic impedances of a buck converter is developed. With this model, a design space is described which characterizes the integration of both active and passive devices of a buck...