Showing papers on "Obstacle published in 1970"

Obstacle Induced Convection in a Toroidal Octupole

Abstract: The effects of hoop supports and other obstacles penetrating the plasma containment region of a toroidal octupole were determined. Obstacles produced large scale convective cells which move plasma toward the field boundary at the azimuth of the obstacles and toward the separatrix at other azimuths. Under certain obstacle bias conditions, 3 V floating potential steps were observed across a dummy support along with 100% density steps. The density step showed an exponential dependence on the obstacle bias potential. A model is discussed which predicts the observed properties of the potential and density steps. Electron cooling at the obstacle was also detected.

Obstacle gain in radio-wave propagation over inhomogeneous earth

Abstract: The obstacle gains are numerically illustrated as functions of the distance between the obstacle and the path terminal for the typical examples of a ridge, a bluff on a homogeneous earth and a cliff at a coastline As the distance increases, these obstacle gains tend to become constants (ie the ridge gain, the bluff gain and the cliff gain that have been previously obtained), while, at short distances, they are directly affected by a diffraction loss, interference between the direct and reflected waves and other effects which are not optical in character A convenient formula for the obstacle gain is introduced for the poor convergence of the relevant residue series The obstacle gain defined here can be understood to be the gain caused by the earth's inhomogeneity and also the gain caused by the antenna height, or it can be the ‘terminal gain’, in the sense that the inhomogeneity in the vicinity of the path terminal is particularly emphasised by the effect of the antenna height It can be used in the same way as the ordinary antenna-height gain over a homogeneous earth

Obstacle Detection Using Stereo WithoutCorrespondence

Abstract: Stereo vision is a straightforward approach for 3D information perception. However image correspondence is the most difficulty in real-time applications. In this paper a qualitative 3D scene verification method is proposed. The global correspondence problem is simplified to an optimization for disparity map parameters. The results of fitting provide the camera pose parameters. The obstacles are then detected from the abnormality of disparity. As we known, simple two-dimensional vision based road following methods are not sufficient for Autonomous Land Vehicle (ALV) navigation in complex environments under arbitrary weather and illumination conditions. They can not recognize 3D obstacles efficiently, and may detect the shadow or water on the road as false obstacles. In this paper the novel qualitative stereo-vision method we proposed is designed for real-time obstacle detection on structural roads. The optimal disparity map of the image pair can be easily computed, and it is a linear function on the image plane. Road scene is verified by the optimal disparity map. A morphology procedure is applied for more reliable abnormal-disparity region extraction. These regions are the focus-of-attention parts for following processing, as obstacle avoidance or object recognition. The algorithm is not correspondence related, so it is very efficient and can be implemented in real-time. Experiments show that this approach is simple and robust. Transactions on Information and Communications Technologies vol 16, © 1996 WIT Press, www.witpress.com, ISSN 1743-3517