Nippon Kokan Kabushiki Kaisha

Nec Corporation

Atsushi Hara

Keiji Nakamura

Hideo Hayashi

Sadayuki Takahashi

Kunio Yamada

Takao Horiuchi

Sigeru Ohtomo

Tatsuaki Takeuchi

Jun-ichi Ogata

In a device of the type of an Inchworm Translator as called by Burleigh Instruments, Inc., N.Y., an electromechanical driver for a shaft of the device comprises a plurality of electrostrictive layers stacked longitudinally of the driver with internal electrodes interposed. Preferably, each gripper or clamper for the shaft is of a like structure and comprises a pair of external electrodes on an outer peripheral surface thereof. More preferably, the gripper comprises either an electrically insulating and abrasion resistive or an electrically insulating and vibration damping film which defines a cylindrical inner peripheral surface of the gripper. The film is preferably divided into a plurality of film portions. The electrostrictive layers are preferably of a composition of a formula of (1-x)Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3.xPbTiO.sub.3 where x is about 0.35. The electrically insulating and abrasion resistive film may be of either a plastic or a ceramic material. The electrically insulating and vibration damping film may be of a ferrite composition having a logarithmic damping factor between 0.04 and 0.06.

Electromechanical translation device comprising an electrostrictive

A method of joining coated large-diameter steel pipes laid underground which comprises placing the steel pipes end to end, applying a layer of heat insulating material to the outer surface of the welding part, covering the ends of the pipe coating the non-coated part of the pipe ends and the layer of the heat insulating material with a layer of a heat fusible, heat adhesive, corrosion resisting material of a shape corresponding to the external shape of the pipes, placing a thin clamp plate around the outer surface of this layer to make it fast, and then internally welding the groove to join the pipes together, whereby the welding heat is utilized effectively and both the corrosion resisting material and the pipe coating are fused by the heat, thus causing the thermally fused corrosion resisting material to adher and solidify on the uncoated portions of the pipes and unite with the ends of the pipe coating and thereby forming a corrosion resisting covering layer. In addition, in the laying of steel pipes there is no need to dig a special excavation of an especially large cross-sectional area around the joint, and upon completion of the assemblying of the above-mentioned various joining material the excavation around the joining part can be backfilled prior to the welding of the joining part of the pipe, thus ensuring speedy laying of steel pipes in the ground, particularly a reduction in the time required from the beginning of laying up to the backfilling of excavation.

Method of joining coated large-diameter steel pipes laid underground

An apparatus detects a leakage position between the upstream and downstream points of a fluid passage, where the fluid leaks. The flow rate of the fluid is detected both at the upstream and downstream points repeatedly at intervals much shorter than a difference .DELTA..tau. between time .tau..sub.1 and time .tau..sub.2 which elapse until a flow rate change appears respectively at the upstream and downstream points. Thus the pattern of the flow rate variation is detected with respect to the time .tau..sub.1 and the time .tau..sub.2, thereby obtaining the time difference .DELTA..tau.. Based on the time difference .DELTA..tau., the distance x between the upstream and downstream points is obtained, thus locating the fluid leakage position, by the following formula: ##EQU1## where l denotes the distance between the upstream and downstream points, and a the speed of sound through the fluid.

Fluid leakage detection apparatus

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Tokyo, Japan

Atsushi Hara