Abstract: .beta.-form tris-(2,3-epoxypropyl)-isocyanurate crystals containing from 2 to 15 wt % of .alpha.-form tris-(2,3-epoxypropyl)-isocyanurate in the interior of the crystals.

Abstract: A method for reducing an organic solvent remaining in tris-(2,3-epoxypropyl)-isocyanurate crystals, which comprises pulverizing crystal particles of tris-(2,3-epoxypropyl)-isocyanurate while evaporating a volatile component from the surface of the particles.

Abstract: A navigation system which can enhance the position determining accuracy of a mobile object without employing any high precision measuring instrument. The navigation system comprises a GPS range measuring device, an angular velocity measuring device, a velocity measuring device and an azimuth measuring device, which measure the motion of the mobile object; a GPS range error estimating device, an angular velocity error estimating device, a velocity error estimating device and an azimuth error estimating device, which estimate errors involved in the respectively corresponding measuring devices; and a position calculating device which calculates the position of the mobile object from the outputs of the error estimating devices. The error estimating devices are implemented by Kalman filters and averaging processes.

Abstract: A vehicle control system and method which can realize automatic driving of a vehicle under control of a base station with a high accuracy of the order of cm, low costs and a high reliability. On the basis of information relating to positions or speeds of other vehicles or fixed vehicles obtained through communication units installed in the vehicles and base station, the system know presence of vehicles in proximity to each vehicle, proximity distances, proximity directions or relative speeds thereof, informs an associated driver of it, or controls movement states of the proximity vehicles to avoid any contact with the proximity vehicles on the basis of the proximity information.

Abstract: In an optical fiber gyroscope, the sensitivity thereof is optimized with a phase bias afforded by utilizing the phase characteristics of an optical branching/coupling unit. Further, the fluctuation of the intensity of a light source and the error and secular change of the phase characteristics of the optical branching/coupling unit are compensated by an electronic circuit. Moreover, an optical fiber loop is located in a heat insulation casing so as not to be affected by an ambient temperature change, thereby to prevent the drift of the optical fiber gyroscope attributed to an temperature change. Thus, the optical fiber gyroscope of high measurement accuracy is provided.

Abstract: The liquid crystal cell (30) for the optical change-over switch comprises a pair of transparent substrates (1), a pair of transparent flat electrodes (2) provided on the respective opposing surfaces of the substrates, orientation control films (3) provided on the flat electrodes (2), two pair of comb shaped electrodes (33) respectively provided on the orientation control films (3), and a ferroelectric liquid crystal layer (4) confined between the substrates (1). The optical incidence plane (31) to the cell (30) is so selected that the plane (31) is away from the helical axes (9) of the ferroelectric liquid crystal in the cell (30) in the order of somewhat greater than the tilt angle (.theta..sub.t) of the ferroelectric liquid crystal.