Abstract: A zoom lens of a four-group structure comprises the following sequentially from the object side, a first lens group having positive refracting power, a second lens group having negative refracting power, a third lens group having positive refracting power and a fourth lens group having positive refracting power. When a variable power takes place from the wide angle end to the telescopic end, at least the second lens group is driven along the optical axis relatively so that the distance between-the first lens group and second lens group is increased and at the same time, the fourth lens group is driven toward the image side.

Abstract: A method of operating an adsorption refrigerator comprising two adsorption columns each housing therein a solid adsorbent and heat transfer tubes and sealed with a refrigerant, a condenser, an evaporator, paths for refrigerant connnecting the adsorption columns to the condenser and evaporator so that the refrigerant may be circulated through the columns, and a pipeline equipped with a valve connecting directly the adsorption columns, which method comprises changing over the adsorption columns periodically alternately between adsorption and desorption phases in manner that the one and the other adsorption columns are at opposite phases and that a heat transfer medium on a heat source side and a coolant are routed through alternately in response to desorption and adsorption phases, respectively.

Abstract: An adsorption thermal storage apparatus formed of an evacuated vessel comprising therein a refrigerant, and an adsorbent heating or cooling section and a refrigerant condensing or evaporating section located in communication with each other, the former section including an adsorbent and finned heat transfer tubes, the latter section including heat transfer tubes placed in dishes. An adsorption thermal storage system comprising the aforesaid apparatus; a heat source (e.g. a condenser of a compression refrigerator) for adsorbent heating; a cold source (e.g. an evaporator) for refrigerant condensation; an exothermic heat source (e.g. cooling tower); an endothermic heat source (e.g. air cooling coil); and a utilization equipment (e.g.

Abstract: An adsorption refrigeration system comprising adsorption columns housing a solid adsorbent and heat transfer tubes and sealed with a refrigerant, an evaporator, a condenser, and pipe lines connecting them together so that the refrigerant may be circulated, the pipe lines being equipped with valves, preferably, butterfly valves, capable of opening or closing by means of internal pressure difference between the evaporator side and condenser side and driving force of eccentric valve shafts. The system is operated by alternatively changing over adsorption and desorption stages between the one adsorption column(s) and the other column(s) so that both columns may be at mutually reverse stages; shortly before change-over, transferring whole amount of heat remained in the one column(s) immediately before shifting from desorption to adsorption stage to the other column(s) immediately before shifting from adsorption to desorption stage where the preheat the adsorbent and then reversing the stages.

Abstract: A zoom lens has, in succession from the object side, a first lens group of positive refractive power, a second lens group of negative refractive power, a third lens group of positive refractive power and a fourth lens group of positive refractive power. The first lens group, the third lens group and the fourth lens group are movable toward the object side for a magnification change from the wide angle end to the telephoto end. The focusing up to a short distance object is made possible by moving the second lens group along the optic axis from the position of its telephoto end toward the object side and moving the third lens group along the optic axis from the position of its telephoto end. The zoom lens satisfies the following condition:-0.5<.chi.3/.chi.2<0.5,where .chi.2 is the amount of movement of the second lens group from the telephoto end toward the object side for short distance focusing and .chi.

Abstract: A zoom lens comprises, in the order from the object side, a first lens group which has a positive power and is fixed in position during zooming, second and third lens groups which have negative powers and movable during zooming, and a fourth lens group which is fixed in position during zooming.When the zoom lens is zoomed from a side angle end to a telephoto end, the second lens group is monotonously moved along an optical axis from the object side to the image side, and the third lens group reciprocates along the optical axis. The zoom lens satisfies the certain conditions.