Hitachi, Ltd.

Hitachi Industrial Equipment Systems Co., Ltd.

Hitoshi Ogasawara

Kenji Baba

Tomoichi Ebata

Shoji Watanabe

Hayao Yahagi

Takamasa Kawaguchi

Yutaka Shimogaki

A position information transmitter including: a digital processing device including a CPU and a position information database storing position information of the position information transmitter and information of channels used by other position information transmitters; and a radio transmitting device executing a signal modulation, wherein the digital processing device generates spread spectrum signals from the position information of the position information transmitter and information of channels used by other position information transmitters, by using the C/A code, and the radio transmitting device modulates the spread spectrum signals and transmits modulated signals as a radio signals.

Positioning system, position information transmitter, communication terminal, and control method of the positioning system

In a positioning system comprising a position information transmitter that transmits a position information signal containing position information indicative of a position as a signal compatible with a satellite positioning signal transmitted from an artificial satellite and a communication terminal that when receiving the satellite positioning signal, finds a current position of the communication terminal by finding a position of the artificial satellite and that when receiving the position information signal, finds a current position of the communication terminal based on the position information, the position information transmitter transmits the position information signal containing a boundary flag that determines which of the satellite positioning signal or the position information signal each of correlators of the communication terminal is to receive, and the communication terminal sets which of the satellite positioning signal or the position information signal each of the correlators is to receive based on the boundary flag.

An apparatus for sludge thickening including a sludge thickener allowing suspended solids of sludge supplied thereto to settle by their own weight while being thickened. The sludge supplied to the sludge thickener is subjected to aeration for a predetermined period of time in a sludge aerator. Aeration of the sludge strips the anaerobic gas, which is attached to the suspended solids in the form of bubbles or dissolved in the sludge, to atmosphere. By aeration of the sludge before being fed to the sludge thickener, floating of the thickened sludge in the thickener can be avoided.

Apparatus for sludge thickening

Process for sludge thickening

An automatic control system in which a controlled quantity of an object to be controlled is compared with a preset quantity through a comparator, the output signal of which is applied to blind controller means having a dead zone set therein. When the output from the comparator comes out beyond the dead zone, the blind controller means cooperates with operation holding means to perform a control operation continuously for a predetermined time even when the output from the comparator falls within the dead zone. The number of times at which the object is controlled may be significantly decreased.

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Kawasaki, Japan

Hitoshi Ogasawara