Abstract: Compositions for low heat cements developed especially for massive concrete works and which exhibit a compressive strength/heat of hydration ratio of at least 7.0 at the age of 13 weeks. One of two inventions provides a powder prepared by mixing CaO, SiO.sub.2, and Al.sub.2 O.sub.3 materials, melting the mixture, quenching the melt, and grinding the quenched matter, the powder being composed mainly of amorphous substances and chemically having a CaO/SiO.sub.2 (molar ratio) of 0.8-1.5 and an Al.sub.2 O.sub.3 content of no more than 10 wt. %. The other invention provides a mixed powder comprising no less than 70 wt. % of a powder and no more than 30 wt. % of an addition (portland cement or the like), the powder being the same as that of the first invention in both predominance of amorphous substances and CaO/SiO.sub.2 (molar ratio) excepting the Al.sub.2 O.sub.3 content which is less than 12 wt. % in the second invention.

Abstract: A piston is free to slide in an engine cylinder, this piston comprising a piston head of circular cross-section, a skirt formed such that it is continuous with the lower part of said piston head, a piston pin passing through the skirt, and a connecting rod connected via this piston pin. This skirt comprises an upper part and a lower part which respectively have an elliptical horizontal cross-section with a short axis parallel to the piston pin, the horizontal cross-section of the upper part of the skirt having a higher eccentricity than that of the lower part of the skirt. The skirt further comprises a taper surface which smoothly connects its upper and lower parts. The contact surface between the skirt and the cylinder therefore has an inverted T shape so that the contact surface of the lower part of the skirt can be increased. It is therefore possible to set the distance from the center of the piston pin to the lower edge of the skirt such that it is no greater than 1.

Abstract: This invention relates to the shape of a skirt below the piston head of a piston in an engine cylinder and continuous with it. The skirt has a basic configuration comprising at least two type of elliptical horizontal cross-section with a short axis parallel to said piston pin, and a barrel-shaped vertical cross-section smaller at its top and bottom. A T-shaped projection is also provided on the lateral surfaces of the skirt corresponding to the two ends of the long axis of said ellipse, this projection consisting of a vertical piece and two side pieces situated on either side of the vertical piece. When the engine is running, the skirt comes into contact with the inner surface of the cylinder via this projection. The vertical section of the lower part of the skirt from below the lower edge of the two side pieces to the lower edge of the skirt is inclined toward the inside of said barrel-shaped vertical section so that the skirt is joined smoothly to the projection below the two side pieces.

Abstract: A piston for an internal combustion engine comprises a skirt portion formed with a piston pin hole. The skirt portion includes in an axial direction of the piston a first portion upper than an axis of the piston pin hole, and a second portion lower than the axis thereof. The first portion has a first cross section formed in accordance with a first ellipse, and the second portion has a second cross section formed in accordance with a second ellipse. The first and second ellipses have two foci, respectively, on a center plane of the piston which is perpendicular to the axis of the piston pin hole. The first ellipse is smaller in ellipticity than the second ellipse. The skirt portion including a ramp portion connecting the first portion to the second portion.

Abstract: A piston assembly of an internal combustion engine is provided with a piston structure with which oil comsumption is suppressed. A piston of the assembly is disposed inside each cylinder wall of the engine and formed with a top land and the second land. A compression ring groove is formed between the top and second lands. A first chamfered surface is formed at the upper peripheral edge of the second land, and a second chamfered surface larger in width than the first chamfered surface is formed at the lower peripheral edge of the top land. A compression ring having a butt-type ring gap is disposed in the compression ring groove to be slidably contacted with the cylinder wall. With this structure, the oil comsumption is effectively suppressed in both high pressure and negative pressure conditions during operation of the combustion chamber corresponding to the cylinder.

Abstract: The pressure prevailing in a variable volume chamber which controls the compression ratio developed by a piston, is used control the movement of a valve which regulates the supply and draining of the chamber. During high load the high pressure is used to drain the chamber while under light load the lower pressure permits the chamber to be supplied with hydraulic fluid in a manner which tends to fill the same during induction phases and the like when the pressure in the cylinder is low.

Abstract: To induce high compression engine operation hydraulic fluid is fed into a variable volume chamber defined between an outer piston and an inner one which is reciprocatively disposed therein via a supply passage which includes a one-way valve. When low compression engine operation is required the pressure supplied to a valve chamber in which a spool valve is disposed is increased to the point whereat the spool valve moves to a position wherein the supply passage is closed and a drain and transfer passages are opened. The drain passage leads directly to the cylinder bore so as to enable the hydraulic fluid in the variable volume chamber to be vented unrestrictedly. The transfer passage permits a small amount of hydraulic fluid to flow through the variable volume chamber to the drain passage in a manner which cools the same and prevents degradation of the hydraulic fluid retained in the one-way valve and the like.

Abstract: This invention relates to a cement-shrinkage-reducing agent and a cement composition comprising a compound of the general formula RO(AO).sub.n H (in which R represents a C.sub.1-7 alkyl or C.sub.5-6 cycloalkyl radical, A represents one or more C.sub.2-3 alkylene radicals, and n has a value of 1-10) for use in making cement mortar and concrete.

Abstract: A method of and apparatus for optimizing the rate of material air supply to an air separation plant, for preserving a stable operation of the plant, through stabilizing heat balance and material balance in the plant irrespective of variation in the flow rate of a gas through an expansion turbine incorporated in the plant and the flow rate of product gases so as to optimize the purity and amount of produced gas. The control for the optimization is performed making a ratio of the difference between the flow rate of the material air and the flow rate of the gas through the expansion turbine to the flow rate of the product gases, as an essential factor for the control.

Abstract: A method and apparatus for automatic change of operations in an air separation plant in increasing or decreasing the amounts of products. The present invention is characterized in that intended change values of the flow rate of feed air to be introduced into an air separation plant, the flow rate of liquid air recycled to an upper tower from a lower tower of a rectification column, the flow rate of recycled liquid nitrogen and the flow rate of an expansion turbine gas flowing in an expansion turbine are computed from the values of increased or decreased amounts of products.