Abstract: The present invention is provided with a key hole insertion fitted to a manhole cover, a manhole cover locking apparatus equipped with the key hole insertion, a manhole cover locking system, a method for unlocking the manhole cover, and a control system for opening and a closing manhole cover, which is designed to prevent an external access to the key hole of the manhole cover, thus attaining a sound and severe locking management. The electrical locking assembly can be added to conventional manhole covers in a simple way. The structure of the invention is characterized in a key hole insertion A inserted in a key hole 3b of the inner manhole cover 3 or the key hole 5b of the manhole cover 5 enough to engage pins 11b with engaging openings 12b of the cap holding member 12 secured to the key hole 3b or the key hole 5b. This allows the key hole insertion A to be locked to the key hole 3b or the key hole 5b.

Abstract: A reliable, long lasting solar battery system capable of collecting and storing long-term data on charge and discharge is provided. The system includes a solar battery having a charge control means, and a storage battery, wherein the charging volume of the storage battery is detected by a charge quantity detecting means. Further, a discharge quantity of the storage battery is detected by a discharge quantity 3c. The detected analog signal is sent through an external interface means to an operation and decision means. An operation and decision means controls a discharge quantity control device, wherein the detected signal, as well as other signals, are processed, together with appropriate various command signals sent by a storage means in accordance with a load or loads, and are outputted to a discharge control means. Further, data on present and past command signals, including the result of past control, are stored in order of time into the storage means.

Abstract: A process for producing a concrete product, which includes a step of preparing a primary concrete by mixing a super dry consistency concrete having a unit amount of water of at most 100 kg/cm.sup.3, a step of preparing a secondary concrete by weighing a suitable amount of the primary concrete and adding at least water, a water reducing agent and a setting accelerator thereto, followed by remixing, and a step of molding the secondary concrete in a formwork.

Abstract: A method of producing a lined Hume pipe wherein an inner surface of a Hume pipe having a large-diameter socket at one end thereof and a spigot at the other end is covered with a synthetic resin pipe.