Abstract: A cis-isomer of perhydroacenaphthene is selectively prepared through hydrogenation of acenaphthene by effecting hydrogenation of 80.degree. to 200.degree. C. in the presence of a Ru and/or Rh based catalyst. A cis-isomer having the highest boiling point is obtained as a major product.

Abstract: Trans-isomers of perhydroacenaphthene are selectively prepared through hydrogenation of acenaphthene by effecting hydrogenation at 200.degree. to 300.degree. C. in the presence of a nickel catalyst on a kieselguhr carrier.

Abstract: A transducer includes a cup-shaped diaphragm having a planar portion in the form of a flange. The internal space of the cup is closed by a metallic support plate. A disc-shaped piezoelectric element has electrode layers on its front and rear surfaces, and the front electrode layer is joined to the inner bottom of the cup. An electrical lead is connected to the rear electrode layer of the piezoelectric element and extends along the external surface of the support plate after it is passed through the thickness of the plate and then bent at a right angle. A resilient member is joined to the external surface of the support plate, and an aluminium sheet is joined to the resilient member. The diaphragm is connected to the ground through the support plate, and the aluminium sheet is also connected to the ground.

Abstract: An apparatus for superimposing a display image of vehicle data or position data of the vehicle on video signals of the surroundings of the vehicle. An object picked up is converted into video signals by an image pick-up camera having an image pick-up drive circuit, an amplifier circuit, a wave shaping circuit, a non-linear amplifier circuit, and a diaphragm control circuit. The video signals are gamma corrected in the non-linear amplifier circuit. Superimposed video signals are read from a memory of stored characters, figures or the like and synchronizing signals are mixed into composite video signals. The composite video signals are superimposed with pattern signals, graphic signals, character signals or the like and displayed by using a liquid crystal or a CRT.

Abstract: To accommodate for a change in the level of a received wave which occurs as a function of the distance between an object, the existence of which is to be detected, and a detector, the detector includes a receiver circuit which has an amplifier circuit having a gain which changes exponentially with an elapsed time since an ultrasonic wave has been transmitted. The amplifier circuit includes ramp signal generating means having an output level which changes in proportion to an elapsed time since a control signal assumes its on level, non-linear signal processing means for non-linearly processing a signal which is output from the ramp signal generating means, and a variable amplification amplifier having an amplification factor which depends on a signal level which is output from the non-linear signal processing means.

Abstract: A plurality of ultrasonic transmitting elements and ultrasonic receiving elements are provided and are electrically switched in a sequential manner to change a region over which the existence of an object is to be detected, thus allowing the existence of an object to be detected over an extended range. The distance to the object and a particular region in which it is detected are displayed. The ultrasonic transmitting elements and the ultrasonic receiving elements are alternately disposed in a linear array. When switching the region over which the existence of an object is to be detected, the switching of the ultrasonic transmitting elements takes place in an alternate fashion with the switching of the ultrasonic receiving elements, thus changing the region at an interval corresponding to one pitch with which the elements are disposed in the array.

Abstract: Ultrasonic waves are utilized to detect the presence of obstacles and to measure the distance between the system and the obstacle. Sensitivity for detecting obstacles is made variable in a manner that a range of the obstacle detecting distance is divided into plural distance regions and different detection sensitivities are set for the respective regions. The distance region to be detected is determined by a time period from generation of ultrasonic waves until reference to signal output made on the receiving side. For a predetermined period of time after generation of ultrasonic waves and for a predetermined period of time after completion of the reference timing to the received output, object discrimination is inhibited thereby to eliminate influences due to direct waves, secondary reflected waves, etc.Immediately after emission of ultrasonic waves, the received output is referred to check the state of the system. If direct waves are not detected, this means that the system operates abnormally.

Abstract: A pneumatic pressure responsive valve assembly includes a housing, a diaphragm piston including a diaphragm member and a piston member, the diaphragm member having an outer periphery secured to the housing and an inner periphery secured to the piston member, two pneumatic chambers defined by the diaphragm piston within the housing, one of the chambers selectively receiving both of the fluid pressures which are higher and lower than those within the other of the chambers, the diaphragm member having a curvature which expands towards either of the chambers, an expanding portion formed on either of the housing or the piston member and corresponding to the configuration of the curvature of the diaphragm member to thereby prevent the curvature of the diaphragm member from turning over, and a valve member for cooperation with movement of the piston member.