SRI International

About: SRI International is a nonprofit organization based out in Menlo Park, California, United States. It is known for research contribution in the topics: Ionosphere & Laser. The organization has 7222 authors who have published 13102 publications receiving 660724 citations. The organization is also known as: Stanford Research Institute & SRI.

Optical-to-Tactile Image Conversion for the Blind

Abstract: This paper describes two optical-to-tactile imageconversion systems being developed for the blind. The first is a reading aid in which an area on the printed page about the size of a letterspace is translated into a corresponding vibratory tactile image. The tactile image is produced by a 24-by-6 array of pins driven by piezoelectric bimorphs. The array of 144 pins fits on the distal and a portion of the middle phalanges of one finger. The piezoelectric bimorphs cause the pins to impact the skin in a nonlinear manner. Precise measurements on this bimorph-finger system are given. These measurements also show that shades of "grey" can be displayed by sequentially varying the threshold level. Three experiments conducted with the reading aid involved measurement of legibility, reading rate, and the effect of field of view. Legibility in the 92-98 percent range was obtained at the design magnification. A reading rate of 50 words per minute was achieved with one subject after roughly 160 hours of practice. Three other subjects achieved reading rates of over 10 words per minute after about 40 hours of practice. Reading rate increased markedly as the number of columns in the array was varied from one to six. The second optical-to-tactile image-conversion system is merely an extension of the first to permit information to be acquired from the environment. In fact, ultimately only one system with two sets of optics, one appropriate for the printed page and one appropriate for environment sensing, would be used.

Recognising and Locating Partially Visible Objects: The Local-Feature-Focus Method

Abstract: A new method of locating partially visible two-dimensional objects is presented. The method is applicable to complex industrial parts that may contain several occurrences of local features, such as holes and corners. The matching process utilises clusters of mutually consistent features to hypothesise objects, also uses templates of the objects to verify these hypotheses. The technique is fast because it concentrates on key features that are automatically selected on the basis of a detailed analysis of CAD-type models of the objects. The automatic analysis applies general-purpose routines for building and analysing representations of clusters of local features that could be used in procedures to select features for other locational strategies. These routines include algorithms to compute the rotational and mirror symmetries of objects in terms of their local features.

Formation of Diamond by Explosive Shock

Abstract: Samples of graphite have been recovered after exposure to explosive shocks of 300,000-atm estimated intensity X-ray and electron-diffraction examinations prove the existence of diamond in this material The mechanism proposed for the formation of diamond under these conditions is simple compression in the c-axis direction of the rhombohedral form of graphite

Structural properties of a carbon-nanotube crystal.

Abstract: Carbon nanotubes of uniform size may soon be available in macroscopic quantities. Here we examine the ordered condensed phase of these tubes. As the tube diameter varies, the structural properties show a clear transition between two regimes with qualitatively different behavior. Tubes 10 \AA{} and less in diameter behave as rigid cylinders. For diameters over 25 \AA{}, the tubes flatten against each other under the van der Waals attraction, forming a honeycomb structure. This structure exhibits an anomalous rigidity, which does not decrease as expected with increasing tube diameter. Based on reported tube sizes, both regimes should be experimentally accessible.