During the 24-hour period ending 1230 GMT May 13, 1957 moderate to heavy convective-type rain occurrecl over a large portion of north central Texas. In consideration of the type of prec.ipitation, amounts were not unusually large, ranging from 1 to 5 inches (fig. 1). However, the most interesting feature was that the rainfall area was well organized and locat,ed in an area where the surface is...

When we manipulate objects in everyday tasks, there are variations in the shape of the grasped surfaces, and the loads that potentially destabilize the grasp include time-varying linear forces and torques tangential to the grasped surfaces. Previous studies of the control of fingertip forces for grasp stability have dealt principally with flat grip surfaces and linear force loads. Here, we stud...

The stability of a thermocapillary flow in an extended cylindrical geometry is analyzed. This flow occurs in a thin liquid layer with a disk shape when a radial temperature gradient is applied along the horizontal free surface. Besides the aspect ratio, a second parameter related to the local curvature is introduced to describe completely the geometrical effects. We recover classical hydrotherm...

White beam Laue transmission diffraction topography has been used to determine the curvature of a crystalline substrate, from which the stress in the overlaying coating is determined. A detailed analytical method has been developed which correlates the introduction of curvature to the substrate in two orthogonal directions with attendant changes in the dimensions of a given topographic reflecti...

This article provides an analysis of gradient and curvature constraints on path form and length, with particular reference to road, rail and pipeline route selection. Initially we examine the case of a single (global) gradient constraint and a planar surface, with or without boundaries and obstacles. This leads on to a consideration of surface representation using rectangular lattices and proce...

This paper studies a specific metric on plane curves that has the property of being isometric to classical manifold (sphere, complex projective, Stiefel, Grassmann) modulo change of parametrization, each of these classical manifolds being associated to specific qualifications of the space of curves (closed-open, modulo rotation etc. . . ) Using these isometries, we are able to explicitely descr...

The present study focuses on geometric features of workspace and joint-space paths of three-dimensional reaching movements. Twelve subjects repeatedly performed a three-segment, triangular-shaped movement pattern in an approximately 60 degrees tilted horizontal plane. Task variables elicited movement patterns that varied in position, rotational direction and speed. Trunk, arm, hand and finger-t...

We investigated whether haptic comparison of the curvature of strips is influenced by the tilt (the average slope relative to the horizontal) of the curved strips. This particular stimulus manipulation was chosen to decide between two broad ways in which dynamic curvature comparison might be done: on the basis of the attitude (slope) differences over the surfaces or on the basis of the attitude...

This paper presents studies of the coordination of voluntary human arm movements. A mathematical model is formulated which is shown to predict both the qualitative features and the quantitative details observed experimentally in planar, multijoint arm movements. Coordination is modeled mathematically by defining an objective function, a measure of performance for any possible movement. The uniq...

When an observer views a moving scene binocularly, both motion parallax and binocular disparity provide depth information. In Experiments 1A-1C, we measured sensitivity to surface curvature when these depth cues were available either individually or simultaneously. When the depth cues yielded comparable sensitivity to surface curvature, we found that curvature detection was easier with the cues...