Abstract: There is disclosed a one-hand openable and closable umbrella which does not cause relative rotational movement and displacement between an inner shaft and an outer shaft. The inner shaft has a U-shaped groove extending in the lengthwise direction thereof and the outer shaft has a convex block provided inside a lower nest mounted on the top of the outer shaft. By the engagement of the convex block of the outer shaft with the U-shaped groove of the inner shaft, the inner and outer shaft neither turn nor displace relative to each other when the latter slides on the latter. Moreover, since a plastic sleeve is put on the upper end portion of the inner shaft inside a spring mounted thereon, any frictional force between the spring and the inner shaft and between the spring and an upper nest can be decreased, by which the umbrella can be smoothly opened and closed.

Abstract: The invention involves the detection of odors using an odor detector including an n-type semiconductor sensor having an electric resistance responsive to odor molecules adsorbed thereonto. An ozonizer is provided within a test compartment to contact the detector with an ozone gas for the purpose of calibrating the detector to an initial zero setting. The test compartment also includes a ventilation fan operable to draw purging air into the compartment. In order to minimize the time required to bring the detector to the initial zero setting, a computer is used to selectively actuate the ozonizer and the ventilation fan in a controlled manner. Before starting a new detection cycle, an operator selects a specific table of optimal pattern for quick recovery to the zero setting from among a plurality of tables stored in the computer, based on certain factors such as the identity and concentration of previously detected odorant substances, etc.