Abstract: The present invention concerns a quick setting composition capable of obtaining satisfactory strength developability irrespective of the fluctuation of the ingredients in a metallurgical slag, excellent in the strength developability at cold temperature, easy for coagulation control and inexpensive as well, which contains a cement ingredient comprising portland cement and/or mixed cement, 2 to 50% by weight at the integral ratio of a quick setting agent prepared by adding 3 to 20% by weight of an alkali carbonate at an internal ratio to a mixture comprising 40 to 95% by weight of a finely powdery metallurgical slag and 5 to 60% by weight of II-type anhydrous gypsum, based on the cement ingredient, and 0.1 to 5% by weight of a coagulation controlling agent comprising an organic acid type coagulation retarder and an alkali sulfate and/or calcium salt based on the total weight of the cement ingredient and the quick setting ingredient.

Abstract: A semiconductor power conversion system comprising a multiphase bridge circuit which includes semiconductor devices having a controllable firing function and a reverse blocking characteristic, a gate control circuit which gives firing commands to the semiconductor devices, a short circuiting switch in which switching devices having a controllable firing function and a reverse blocking characteristic are connected in parallel with a DC output side of the multiphase bridge circuit, and a protection control device for performing a control for protecting the multiphase bridge circuit.

Abstract: An improved electric power conversion system comprising a multi-phase bridge circuit composed of semiconductors such as thyristors and an associated firing circuit. It is so constructed that: if the AC input current Iac flowing in the bridge circuit is equal to or larger in value that the DC output current Idc flowing out of the bridge circuit, it will be decided than an inner defect or fault is caused, and possible expansion of inner defect will be prevented by disabling the firing circuit to extinguish the thyristors in the bridge circuit, and if the AC input current Iac is smaller than the DC output current Idc in value, the bridge is permitted to continue the operation of power conversion, thus eliminating unnecessary interruption which otherwise would be caused by exterior disturbances. Also, an improved electric power conversion system may be equipped with a device to prevent an adverse effect from being caused by abnormal rise of thyristors' temperature.

Abstract: An analyzer of partial molecular structure analyzes a specimen material within an absorption spectrum. In addition to the wavenumber of peaks of an infrared absorption spectrum of a specimen, an analyzer analyzes molecules within partial structures using the strength of the peaks of the absorption spectrum so as to improve analysis accuracy.

Abstract: A generator-motor apparatus with economical protection measures for use in a variable speed pumping-up electric power plant, having a main transformer, a secondary winding of which is coupled to an electric power system, a power system breaker connected to a primary winding of the main transformer, a syncronizing breaker connected in series with the power system breaker, a generator-motor, a rotor of which is mechanically coupled to the pump-turbine and an armature winding of which is connected to the power system through the synchronizing breaker, the power system breaker and the main transformer, and an excitation circuit, including a frequency converter for supplying a field winding of the generator-motor with AC voltage of the variable frequency and a converter transformer for feeding the converter, which is branched from a junction of the power system breaker and the synchronizing breaker.

Abstract: A preheating apparatus of an analysis apparatus for determining the in quantity hydrogen and carbon contained in a sample such as steel is employed to remove moisture adhered to a sample of the steel by spot-heating focused on the sample in a transparent bent tube which is turned one-half in its circumferential direction after completion of its preheating to make it possible for the sample to be transfered by gravity from the bent tube into a graphite crucible in which the sample is fused to extract hydrogen and carbon contained in the sample, so that the thus extracted hydrogen and carbon are determined.

Abstract: A method and apparatus for determining the chemical structure of an unknown substance wherein spectral data of the unknown substance is detected, a point-assessment is calculated which expresses the degree of possibility of partial structures being contained in the unknown substance based on the spectral data and prememorized chemical shift values corresponding to the partial structures of known substances, it is judged whether the point-assessment is a predetermined threshold value or more and the partial structures with a large possibility of being contained in the unknown substance based on the output of the judgement results are found and displayed. The partial structures thus found are used to determine a molecular structure of the unknown substance.

Abstract: The present invention provides a carbon-containing refractory composition characterized by containing 0.1-10 parts by weight of silicon hexaboride in 100 parts by weight of refractory material comprising 3-95 parts by weight of carbonaceous material such as graphite and 97-5 parts by weight of refractory aggregate.In the carbon-containing refractory composition of the present invention, silicon hexaboride is oxidized producing boron oxide on the surface of the refractory at a high temperature during operation, and the surface of the refractory is covered by the formation of a highly viscous molten liquid like kotoite (3 MgO.B.sub.2 O.sub.3), for example, which is formed from the components of the refractory, such as MgO, for example, thus particles of carbonaceous material such as graphite can be protected from oxidation.

Abstract: In a rolling mill having a pair of upper and lower work rolls, defining a pressure gap therebetween through which a material is passed to be rolled, a method and apparatus for controlling the rolling mill under the different peripheral-speed rolling operation in which one of the rolls is driven at a predetermined peripheral speed by controlling the speed of a motor for driving the one roll, and the other roll is controlled to generate a torque corresponding to a difference, between a total torque required for the rolling operation and a torque generated by the one roll by controlling the torque of the motor for driving the other roll on the basis of a torque command corresponding to the torque difference.

Abstract: A process for the preparation of pellets is disclosed which comprises mixing an iron ore raw material with a pitch material having a softening point of 30.degree. to 300.degree. C. in an amount in the range of 0.5 to 5% by weight of the iron ore raw material, molding the mixture, and heating the molded material under a reducing atmosphere to remove arsenic contained therein.